Mars Rovers Update

BoldAC writes "CNN is reporting that engineers will upload a software hack to decrease the recent power drain plaguing the rover Opportunity. The hack works by reducing the power supply to a poorly functioning switch." p3tersen writes "Opportunity has photographed a blue martian sunset (it's blue because of the optical scattering properties of dust in the martian atmosphere). In other news, the rovers are beginning to experience power supply problems due to the accumulation of dust on their solar panels."

Comments

Hey, where are the conspirency theorists...

[imsabbel]

Was the sunset REALLY blue?

Re:Hey, where are the conspirency theorists...

[TimeZone]

No, this one was really RED.
TZ

Gentoo?

[Anonymous Coward]

I use Gentoo; how does this affect me??

Planning Ahead

[Piethon]

Maybe it would be better if we tested the software more on earth and had all the bugs worked out before we sent it up. It seems like all of these problems could have been avoided if we would have just uploaded the software BEFORE we launched them and had thorough testing. If NASA would do things other than try to get pretty pictures to increase its funding, maybe something more might come out of it.

Re:Planning Ahead

[toast0]

How does testing the software determine the heater is going to malfunction?

Given CNN's lack of technical depth, for all we know it could be a command to the rover to tell it not to turn on the heater anymore. Either way, they designed the rovers so they can fix them while they're in space, which is pretty good.

Given the limited amount of storage on the rover, it's a higher priority to make sure the upgrade process works, and that it is possible to fix stuff with software, than to make the rover fix stuff automagically.

Re:Planning Ahead

[jeff munkyfaces]

i'm sure they thought they had ironed out all bugs.

More useful, and what appears to have been implimented, would be a system where they can easily upload fixes/patches when un-expected errors appear.

Re:Planning Ahead

[Tablizer]

Maybe it would be better if we tested the software more on earth and had all the bugs worked out before we sent it up.

They had a small time-window to get a lot of stuff ready. Because of the politics of funding, often they only have about a 4-year lead to put it all together. Plus, Mars is only in the right position about once every 2 years.

Re:Planning Ahead

[dellis78741]

The updates include improved driving software, something that only evolves after some hands-on time on Mars itself. The patch to strangle the errant heater is pretty drastic - it shuts down some primary circuits including the internal clock, which has the -side- effect of cutting off power to the heater overnight. The rover will wake up the next day only when it starts to get some sunlight on its' solar cells - not by an alarm clock as it does now. The heater will still run once the rover wakes up the next day.

Re:Planning Ahead

[Winkhorst]

At the immediate risk of being modded "-5 Enemy of Computing," I find this whole fix-the-programming-after-it's out-the-door scene rather familiar, though I can't quite remember where I've seen it before. Perhaps it has something to do with those continuous "updates" I'm supposed to install from Microsoft and Corel and a dozen other companies' programs I have running, both paid and free. And I find the reference in the above post to "improved...software" quite hilarious, actually. Like it's right out of thousands of advertising blurbs that tell me over and over I absolutely HAVE to upgrade my pathetic old programs, especially since they won't work with the NEW AND IMPROVED operating system. Will this nonsense never end? Will no one ever admit that the programming is so fnuxed that they have to keep "upgrading" it to keep it from blowing up every time the user tries to do something other than write a form letter?

That the programmers working for a government agency on a project that's costing the taxpayers vast amounts of money can't get past this idiocy that one shouldn't have to put up with from some mickey mouse game manufacturer quite boggles my mind. There is a level of arrogance here that is positively beyond understanding. What other professional or maker of goods would sell something with the express assumption that it might not work right and may have to be fixed later? And to cite this as some kind of incredible example of foresight is off the Richter Scale of unbelievability.

Re:Planning Ahead

[dellis78741]

I think its' safe to say that the approach to programming that the rover programmers use has little in common with that of some large software companies. "Getting it out the door" (ie, launch it within the possible window) involves a firmer deadline than any MS programmer -ever- faced. They actually uploaded a new version of the driving software while the rovers were enroute to Mars.

Re:Planning Ahead

[SEWilco]

NASA was simply leading the way in future-feature technology. Send it to market, and later update with new features.

Re:Planning Ahead

[Ancient_Hacker]

IIRC the 3M company makes some polonium-powered dust-neutralizing brushes-- something about the beta rays charging the dust particles so they repel each other. Any idea why this couldnt be done to the solar panels?

Re:Planning Ahead

[shaitand]

While your probably right that nobody but a programmer would release something with the understanding it will inevitably have some kind of problem that needs fixed down the road. What you seem to be missing (probably because your not a programmer?) Is that there aren't really many other things out there that are as complex, have as many potential failure points, and that is as individually unique everytime inventing a completely new and previously untested invention, as the code which creates a text editor.

Let alone anything more serious like an operating system or rover control software ;) People like you are the same one's who don't understand why programmers make as much as they do. Computer programming is easy, what's hard is doing it right, and there is very little in higher physics or rocket science that could begin to complete with writting a complex program the right way ;) Why do you think the best programmers in the world collaborating to produce the best software they can and with literally millions of programmers reviewing the code for bugs STILL have an occasional glitch that makes it out the door?

Do you really think that when the best talent in the world with millions of debugging programmers can't produce a bug free program it's something you can simply throw money at and fix? The US government itself couldn't afford or find as many programmers to hire that work on a single popular open source project.

Re:Planning Ahead

[Winkhorst]

Your reply is a classic example of what's wrong. You don't even have the common sense or respect for your readers or just the educational foundation to read over your own post and remove the obviously incorrect word usages. "Your" for "you're"? You don't know that "you're" is a contraction for "you are"?

As for being modded "troll," I predicted that, didn't I, and it's pretty obvious I am not trolling anyone here. I am expressing my opinion and that of a huge number of computer users who are sick of so-called software that doesn't work out of the box. This is just an easy way of putting your heads, ostrich-like, in the sand. Can one not criticize a deficiency without being categorized as something other than genuine? Come on guys. This isn't a video game. You need to learn to take responsibility for your own shortcomings and stop making excuses.

Re:Planning Ahead

[shaitand]

tsk tsk shame on me, you truely are a troll. I'm amazed you managed to write that entire reply without a single sentence that any relevance or content which in any way counters my argument.

But you want strong opinions without any sort of factual backing or making any actual legitimate points or logical debate. Ok wth, I'm bored.

No, you cannot critize something you percieve as a deficientcy without being categorized as something other than genuine. To do that you have to get off your ass, stop whining and bitching about the best some of the most intelligent minds of our time can produce with the aid of literally millions of proofreaders, show us the perfect bug free software you've written... of course it has to remain so after being scrutinized by millions of programmers who enjoy nothing more than beating your creation with a stick trying to figure out if they can come up with a single point in which you fucked up.

I saw someone try your argument once, he was asked to show some bugfree code. He wrote the most basic and trimmed down "Hello, World!" routine you could imagine, within an hour he had more than 6 replies with bugs and security holes the casual programmers on slashdot happened to notice just glancing at it. Let's see you do better.

Opps sorry, tried to stick the baseless emotional outbursts crying for justice but someone logic creeped in. Lets hope you can at least keep your rant on the subject of programming and software this time instead of whining about a piece of grammar which is incapable of actually causing confusion or misunderstanding.

Solar problems

[LotsaCaffeine]

NASA should have installed wiper blades on the solar panels.

Re:Solar problems

[MikeCapone]

NASA should have installed wiper blades on the solar panels.

I know you are joking, but I'm actually surprised that they haven't thought of a way to keep the solar panels clean.

I mean, they can get the thing to mars, they should be able to do that, no?

Re:Solar problems

[r00zky]

For an easy solution see: helmets of Formula One drivers.

Re:Solar problems

[Anonymous Coward]

Every easy solution has a problem. The problem with this one is that the Mars rovers don't have any arms to rip the layers off.

Re:Solar problems

[Anonymous Coward]

And just who is going to pull off the tear-off? The Martian pushing the rover along?

Yet another stupid idea from another wannabe engineer.

Re:Solar problems

[r00zky]

A thread attached to a corner of every plastic sheet running diagonally to the opposite corner and an electric motor that activates when the sheet is dirty.
Stack 10 sheets of this and voila, lifetime of the rover multiplied x10.

Re:Solar problems

[IgnoramusMaximus]

You are kidding for sure.

Say, a step motor and some mechanical jiggery-pokery ending with a stiff wire, a hook on its end, the layers would have tabs with holes in them to pull at.

Or.. a glue between layers that deteriorates on contact with Martian athmosphere and so the layers will peel off after a fixed (based on chemistry) time.

I mean, give me a break, those took less then 10 seconds to come up with and I am sure NASA engineers could have thought up much more effective methods.

Re:Solar problems

[hottoh]

I understood Nasa to say 'wiper blades' would not be effective due to the nature of the fine dust chemically sticking to the surface of the solar cells. Mechanical sweeping does not solve the real problem of the dust sticking to the solar panel.

Just a guess based on Nasa commentary is the batteries will fail before the solar panels fail to charge them.

Re:Solar problems

[Anonymous Coward]

If only life were so simple, you'd be working for NASA...

How is the motor supposed to pull the correct wire (you wouldn't use thread)? Ten different motors?

What do you do with the tear-off once you pull it? Leave it clumped at the bottom or just have hang around trailing behind the rover or right on top of the panels? Cut the wire you say? Kind of difficult to do that if you rolled the wire up on a spool with a motor. Going to need ten pyros for that.

Don't forget that you have to pack all of this onto the rover and fold up the panels. Better hope your wires don't tangle up and prevent the panels from unfolding.

All of this stuff takes up weight and adds complexity. Do you really want to do all of that?

Re:Solar problems

[nomel]

but then the rovers might last forever, and they wouldn't as easily get funding for new projects.

if you think about it, the reason has to be some conspiracy like this...seriously.
We got the thing to the moon, but we can't keep dust off the solar panels...come on!

Re:Solar problems

[Anonymous Coward]

I wonder if NASA considered parent's idea. If not, parent post is great argument for running the next generation of probes sent (somewhere) past an open discussion forum.BR.or do they alredy do that?

Re:Solar problems

[ModernViking]

First, my credentials. I have worked on the field trials of the FIDO rover. It is the science test bed for the MER rovers that has been tested in various parts of the western United States over the past 6 years.

There have been many ideas tested for the solar panels, including removable plastic coverings, wiper blades, etc. None of them have proven practical. The dust on Mars is extremely fine and electrostatically charged. It sticks to the panels , and every other surface, amazingly well. Figuring out a way to remove Martian dust from surfaces is a field that a lot of thought and experiment has gone into, without discovering any feasible solutions, so far.

During the Pathfinder Mission in 1997, it was found that, by driving the rover over 'large' rocks (large for the rover), some of the larger dust can be shaken off. This is, as I've heard from members of the engineering team, something they intend to try with the MER rovers when needed. It doesn't make a huge improvement, on the order of a couple percent, but every little bit helps.

Re:Solar problems

[Bull999999]

Another problem with rovers lasting forever is that they may gain AI, build themselves up with other technology, and go on a killing spree until a witty captain of a spaceship stops it.

Re:Solar problems

[Flakeloaf]

If the dust is electrostatically charged, what would be involved in covering the solar panels with a thin, transparent film or network of wires that is itself charged to repel this dust?

Re:Solar problems

[torpor]

Put the solar array on a vibrator, tilt the rover slightly, and give the solar panel array 15 minutes of shaking at some appropriate Hertz... oila, dust is shaken off.

Re:Solar problems

[Anonymous Coward]

How is the motor supposed to pull the correct wire (you wouldn't use thread)? Ten different motors?
A simple set of 10 mechanical gears made of plastic and stacked in a row would do this. The driving gear jumps from first to last as needed. My printer does something similar to this everyday to a precission of 720 dpi so...

What do you do with the tear-off once you pull it?
Cut the wire between the plastic sheet and the gears that rolled the wire. No need to have 10 cutting devices, since only one wire will get rolled at a time.

Don't forget that you have to pack all of this onto the rover and fold up the panels.
Implement one of these in each fixed panel, not in the panels as a whole.

All of this stuff takes up weight and adds complexity
Sending 2 probes to Mars and getting scientific data back is waaaaay more complex than this. And the weight... it adds a little more $$ for fuel, but the result is a _much_ longer lifetime.

Re:Solar problems

[IgnoramusMaximus]

A vibrator? Might work although probably could be destructive...

Hmm, after another 15 minutes of mental effort: a thin brush on an arm mounted to the side of the camera mast. You lower the (very thin and light single file brush) with a small step motor to the horizontal position and then you rotate the camera mast to create a sweeping motion on the panels. You could brush the 2 side panels that way, since if you planned for it, there would be no portruding gear to get in the way of the brush (all such gear would be back of the mast).

And so on...

I am really flabbergasted why there is absolutely no provision for any sort of cleaning (even a partial one) on the rovers. Its not like this wasnt expected. I smell some sort of hidden agenda in shortening the life of the rovers.

Re:Solar problems

[Anonymous Coward]

Going to need ten pyros for that.
Forgot to say: no need to put the rover in fire, a tiny mechanical dented-guillotine device should have no problem cutting a wire similar to that used for fishing.

Re:Solar problems

[deglr6328]

Can you say more about why specifically the peel off transparent plastic idea was rejected(it seems to be the simplest, most effective, non-single point failure prone, most elegant solution I've seen so far)? I know all these speculative posts seem tedious and redundant, it's just that it seems like such a shame to allow the mission life of the rovers to be so severly shortened by such an apparently trivial problem.(it's just a little dust!! :o)

Re:Solar problems

[Anonymous Coward]

I know you are joking, but I'm actually surprised that they haven't thought of a way to keep the solar panels clean.

I mean, they can get the thing to mars, they should be able to do that, no?

Ummm, no... We're talking about Americans here afterall...

Re:Solar problems

[Anonymous Coward]

The cost of the extra fuel is utterly irrelevent for a mission like this. It's the *weight* of the extra fuel that is the problem. Additional weight (and complexity) on the rover requires extra fuel. The weight of that fuel requires even more fuel to lift it, which in turn requires more fuel .... ad infinitum. Of course, the increase in fuel each time is of a diminishing amount so there is a limit. Weight is however the number one problem to overcome when designing aerospace vehicles.

Re:Solar problems

[jeff munkyfaces]

would it be possible to set them into "violent shaking mode" to solve this?

Re:Solar problems

[Anonymous Coward]

Well... that must be one reason why i don't work in the NASA :) the other being that i'm not in the mood of going to the USofA anytime soon, not even payed.

Re:Solar problems

[geekoid]

I would love to see notes from these kind of 'thought' groups. It is a big problem, and I think it should be put out into the public. Maybe a contest.

If you think the people t NASA can't figure it out, then nobody can, you are just kidding yourself.

Re:Solar problems

[taion]

The dust is electrostatically charged, so simply detaching the plastic layers wouldn't be sufficient, as they'd still be stuck onto the panels. You'd need some way to do more than just cut off the layer.

Additionally, even transparent plastic would reduce the amount of light striking the panels by some amount. Multiply that by however many layers you want, and the effect likely becomes significant.

Re:Solar problems

[Daniel_Staal]

Of course, you are assuming all the dust has the same charge...

Not a likely situation.

Re:Solar problems

[takev]

Or you could go the way of how formula 1 cameras work. They use a roll of transparent plastic sheet, attached to a single motor. Exactly like a photo roll.

The technology is very sturdy and well proven, as it is used on formula 1 cars.

Re:Solar problems

[IgnoramusMaximus]

None of them have proven practical

I dont buy this for a second. Removal of fine, electro-statically dust, has been practiced on this planet for centuries if not millenia. There are entire industries based on this practice. I am convinced that it was one of those famous NASA managerial pissing contests that ensured no "feasible" or "practical" solution. Read: the companies which proposed the solutions were not part of the "in" crowd.

Re:Solar problems

[Schemat1c]

Every easy solution has a problem. The problem with this one is that the Mars rovers don't have any arms to rip the layers off.

[sarcasm]
You're right. I guess we will have to wait until someone invents robotic arms. And anything spring loaded wouldn't work because everyone knows springs don't work on Mars.
[/sarcasm]

There is nothing that can convince me that there is no way around this problem. It amazes me as much as the fact that NASA had prepared absolutely no way around losing a few tiles on the shuttle. These are major problems with simple solutions.
I think we have the wrong people running our space program.

Re:Solar problems

[Anonymous Coward]

There have been many ideas tested for the solar panels, including removable plastic coverings, wiper blades, etc. None of them have proven practical.

what about a Swiffer?

Re:Solar problems

[IgnoramusMaximus]

There is nothing that can convince me that there is no way around this problem.

Same here. I am more and more convinced it was some kind of political/managerial cockup. NASA is famous for having roaming bands of pointy-hear manager morons who engage in turf wars and pissing contests between each other either due to influence peddling on behalf on contractors or just because they are jerks with egos the size of Texas. That was the main reason behind the 2 shuttle accidents and I am sure it has some part to play in this as well.

Re:Solar problems

[Senjutsu]

Which would repel all the dust of the same charge, but attract the rest. Plus you've added the possibility that something could short across this wire grid and drain the battery real quick.

Re:Solar problems

[Anonymous Coward]

Why do people always mod up the stupidest posts by the most idiotic bastards?

Re:Solar problems

[bani]

how about a conveyor belt of plastic which wraps around each panel (eg, goes over the collectors, to one edge, through the panel surface and wraps around underneath and comes back up through the panel at the other edge of the collector). at one edge is a brush which traps the dust. you just run the belt to transport the accumulated dust off the panel, as many times as needed.

furthermore it's just one layer, so it wouldnt reduce the light as much as multiple removable layers.

Re:Solar problems

[CdBee]

Why not just use a high frequency transducer to clean the surface of the panels?

Tilting and vibrating them might, possibly, shake some of the dust off?. Obviously this has to be balanced against the wear caused by the vibration so it may not be possible...

Re:Solar problems

[Anonymous Coward]

You sound like a british faggot. Cockup, indeed.

Re:Solar problems

[jeff munkyfaces]

this still has the problem of dust sticking with static, how you clean the brush, and scratching the plastic with grit..

Re:Solar problems

[Joey7F]

Not sure where you are from, but unless you are from the United States, regale us on all of your nation's sucessful space pursuits :)

--Joey

Re:Solar problems

[Anonymous Coward]

Because the moderators are idiotic bastards?

Re:Solar problems

[johannesg]

Have you tried to polarize the hull plating? ;-)

Alternatively, do what we do here on earth: spray them with windscreen fluid...

Re:Solar problems

[Anonymous Coward]

And anything spring loaded wouldn't work because everyone knows springs don't work on Mars.

Actually, yes, springs work totally different on Mars. For example, you have to multiply the spring constant with 0.65 because of the different gravity.

Re:Solar problems

[Anonymous Coward]

Does your windex take off rust that's chemically bonded? Have you seen the before and after brushing pictures from Adirondack? No? Well maybe the problem is a little more complicated than you are assuming. Large grains of dust can fall off the panels. Smaller grains are now fused to and have become part of the panels.

The questions shouldn't be on how to extend these pissant solar panels, but on why they didn't put an RTG in in the first place.

Re:Solar problems

[dealexander]

I wonder if they considered a system similar to the one that wipes the dirt of the NASCAR bumper cams and the overhead cameras at football games. The system must be transparent and does a good on the TV I've seen.

Re:Solar problems

[Anonymous Coward]

Not exactly. The batteries will fail once the rover cannot put out enough power to keep the warm electronics box that they are in warm. At some point the power put out by the solar panels will not put out enough power to charge the batteries so that they can keep a constant temperature in the WEB. Once that happens, it will cool down so that each successive day the WEB will get colder. This also means that the batteries will have a lower and lower capacity each day (temperature related). This amplifying effect will cause the rapid failure of the batteries a couple of days after the initial loss of temperature control degradation, which will kill the rover once the WEB cools down to normal Mars temperatures.

Re:Solar problems

[Dun Malg]

I dont buy this for a second. Removal of fine, electro-statically dust, has been practiced on this planet for centuries if not millenia. There are entire industries[windex.com] based on this practice. I am convinced that it was one of those famous NASA managerial pissing contests that ensured no "feasible" or "practical" solution. Read: the companies which proposed the solutions were not part of the "in" crowd.

The key difference you're missing is, in your own words, "on this planet". The fact that the rovers are on mars has two important effects. First, the atmospheric composition, weather conditions, and the nature of the martian dust itself render common dust abatement methods here on earth ineffective. The most common, spraying liquid and wiping, is totally out of the question when the temperature is -20 to -80 degrees C. Second, the inaccessability of a rover on mars means that complex mechanical "wiping" solutions are out of the question-- there's no one there to smack the side of the unit when a cam arm gets stuck, or replace a solar panel when a wiper blade gouges it with a sharp pebble.
If you're so sure there's an easy solution, let's hear it. Your bizarre conspiracy theory makes no sense.

Re:Solar problems

[IgnoramusMaximus]

...rednder common dust abatement methods here on earth ineffective

While thats true, we know hell of a lot about properties of dust in myriad of conditions. Things like conductive surfaces as means of reducing the clinging force, things like translucent films that can be peeled off the surface of the panels along with the dust, things like liquids that do not freeze even below -80 and have similiar properties to the common solvants etc etc etc. Not to mention mechanical solutions like vibration and high pressure gas jets (small chemical charges or compessed CO2 or some such). I mean thre are miriad of potential solutions to one of the most common problems human kind ever encountered!

Re:Solar problems

[Anonymous Coward]

What if it worked like 35mm film cassettes? You'd have a limited length of film, but the unused film would be tightly wound and not exposed to the dust. The "take up" reel would never be reused, so brushing wouldn't be necessary.

Re:Solar problems

[Anonymous Coward]

what if they had an unbrella deploy to shelter the rover when it had no sun? at least it would decrease the amount of dust!

Re:Solar problems

[JPriest]

I don'tunderstand what you are saying here, if there was a plastic layer on the panel the dust would be on it, not the panel.

Re:Solar problems

[SmackCrackandPot]

Would high frequency vibrations work? When I worked in Canada, there used to be these beetles which be attract by the light from my halogen lamp and try and bury themselves into my pot plants (if they didn't fry themselves first).

Being particularly curious, I dug a couple out of the soil. Being covered in dust, the first thing they would do is make a loud buzzing noise to warm up (and which would shake off the dust) and then open their wing case and take off.

Would this method work with solar panels?

Re:Solar problems

[Lawrence_Bird]

Damn it! Rudy Giuliani made it to Mars first and
got rid of all their squeegee guys!

Re:Solar problems

[GileadGreene]

It's not a case of a few more $$ for fuel. It's a case of being able to launch at all. The rovers BARELY made it under the max launch mass. They were even over the max at some points in the program, and were stripping off mass whereever they could. Besides, in the space business additional mechanisms are frowned upon due to both the difficulty of designing a mechanism to work in the space (or martian) environment, and the inherent decrease in relaibility of the overall system. MER already has far more than mechanisms than is usual for a space mission.

Re:Solar problems

[Anonymous Coward]

CNN is reporting that engineers will upload a software hack...

OH NO! They have hired Microsoft Windows maintenance programmers using "Windows Update" technology!

Re:Solar problems

[NanoGator]

"I know you are joking, but I'm actually surprised that they haven't thought of a way to keep the solar panels clean."

Who says they haven't thought of a way? The problem is practicality. Wipers on the panels means scraping dirt and rock etc across the panels, potentially scratching them.

Is there a solution? Oh quite possibly. But I too would be quite nervous about trying to engineer one. Nothing I've brainstormed is ideal.

Re:Solar problems

[NanoGator]

"I mean, give me a break, those took less then 10 seconds to come up with and I am sure NASA engineers could have thought up much more effective methods."

Well hold on. It's easy to come up with ideas. Just remember that they know what the environment of Mars far better than you possibly could. This is not an insult. For problems like this, there's no such thing as a 'simple answer'.

Re:Solar problems

[lquam]

Ok, then how about a simple solution... blowers. Put a couple of small compressors on the thing to suck up some of that thin Mars atmosphere. Have each of 'em tied into a few nozzles in redundant locations so if one compressor goes down or a nozzle gets clogged you've got backups. Get some good pressure in the tank and let it rip. If one shot doesn't clean things up, fire up the compressor again and keep doing it until you've got a clean panel.

Or, heck, it's perhaps more moving parts but how about just a couple of those fans OC'ers like to use to keep their overclocked Radeon 9800s from exploding. Yeah, the air is thinner on Mars, but there's also a lot less gravity holding the dust on the panels--I bet a 7000 RPM fan on a good old oscillating base would fill the bill.

I bet when they were testing these things on Earth and a panel got a little dusty some engineer walked over to the thing with a can of dust-off. Anyone want to volunteer for a one way trip armed with a can of compressed air and a 512 MB CF card to plug into the thing. Oh, and you could sprinkle some water in front of it to; that would get everyone excited!

--Len

Re:Solar problems

[IgnoramusMaximus]

For problems like this, there's no such thing as a 'simple answer'.

In general, when problems are complex, I would agree. But we are talking about dirt here. Something people have been cleaning for millenia from all imaginable surfaces in all imaginable conditions. I just will not accept any cop-outs in the vain of "Oooh .. dirt on Mars is like ... Space Dirt, man! Its magical!". As many others and myself pointed out in other messages on this thread, this particular technical problem is just too dumb to not have a feasible solution. Therefore things other then shortage of engineering creativity are far more likely to be the cause of not having such solution in place.

Re:Solar problems

[NanoGator]

" I just will not accept any cop-outs in the vain of "Oooh .. dirt on Mars is like ... Space Dirt, man! Its magical!"

Dirt that contains chemicals that interact with the material of the panels == Magic Space Dirt.

You're stuck in "lemme oversimplify so I can solve these guys problems" mode. It's draining your batteries.

Re:Solar problems

[IgnoramusMaximus]

Dirt that contains chemicals that interact with the material of the panels == Magic Space Dirt

And so you design the coating of the panels just so it actively reacts with Martian dust or athmosphere. Composition of which is pretty much known. And forget our extensive knowledge of ceramic and silicon based coatings. Not to mention other more exotic materials.

You are stuck in "lemme make things seem way more complicated then they are so I can defend those guys no matter what mistakes they make" mode. Its draining your batteries.

Re:Solar problems

[NanoGator]

"You are stuck in "lemme make things seem way more complicated then they are so I can defend those guys no matter what mistakes they make" mode. Its draining your batteries."

I'm not the one assuming that Nasa engineers are stupid here.

Re:Solar problems

[Anonymous Coward]

And why don't they make the whole plane out of the black box material?

Re:Solar problems

[IgnoramusMaximus]

I'm not the one assuming that Nasa engineers are stupid here.

Neither am I. The same cannot be however said about the managers of NASA and all the other assorted bureaucratic bullshit that goes on there. My theory is that the engineers knew very well this is going to happen but some other politcal reasons exist for which no solution was made. And so now engineers must tow the company line.

Re:Solar problems

[bani]

use a polonium source same as is used in anti-static brushes. works _perfectly_ to neutralize any dust charge. if it's good enough for professional photographers to remove statically charged dust from negatives, it's good enough for this.

look at the tape cleaning systems that have been around for oh, about 100 years... those problems have long been solved.

Re:Solar problems

[cswiii]

The dust on Mars is extremely fine and electrostatically charged. It sticks to the panels

Man, and to think that for five easy payments of $69.99, NASA coulda gotten an Ionic Breeze from Sharper Image to fix that!

Re:Solar problems

[Stumptom]

First of all, like many millions have said before : First Post. I like this idea of electro-static "brushing" of the surface. Can't it just degauss by switching in inverse polarity ? And then come back to the polarity observed to repell most of the dust... With a big fat assed 21" inch monitor degauss noise : whoooooosh...

Re:Solar problems

[IgnoramusMaximus]

Does your windex take off rust that's chemically bonded?

Why oh why would someone coat the panels with something that can even remotely be prone to chemically binding with soil?! And I am going to repeat the million times mentioned simple solution of a peel-off film! And guess what? ONE coat of peeloff film means twice the lifetime of the rover. Ponder that!

BTW, the RTGs are so politically loaded that noone is going to send any anywhere anytime soon. Besides they are apparently much heavier then they wanted the rovers to be for the types of boosters they could afford.

Re:Solar problems

[ElliotLee]

I'm pretty sure those plastic sheets would lower the amount of energy the panels could produce - just another layer to block sunlight from an already inefficient system.

Re:Solar problems

[mnmn]

Here are some ideas I'm sure have been considered:

(1) Vibration.... the panels are lifted sideways and a motor at the top vibrates them for a few minutes. This will cost(1) the vibration motor (2) the lifting motor (3) lifting arm and hinges.

(2) Clapping two solar panels together.

(3) Compressed air. This is my fav. A small cylinder onboard could blow air across the panels about 10 times... increasing the life of the rovers 10 times. If theres enough gas in the atmosphere, replace the cylinder with a compressor. Its mechanically easy, less risk, and with a tiny compressor will add just a tiny bit of weight.

(4) Wiper blades. The blades will have feathers on them like a feather duster.

(5) Rotating panels. The panels would be disc-shaped and are rotated real fast like a CD to shake off the dust.

(6) Flippin panels. Turn the panels upside down for a little while. Optionally, jerk them.

(7) Roller film. Unlike camera film, one loop of film covers the panel and two axels at the panel ends loops the film around. Small brushes at one end will keep cleaning the film.

(8) Driving into rocks. The rover can tilt its panel forward facing and drive into a large rock with a bumper. That way the martians wouldnt think much of our intelligence and cancel the invasion.

(9) Tiny micro-rovers built by MIT undergrads to wander over the panels cleaning it. The micro-rovers will themselves have connectors to recharge. I'm thinking 2mm^2. Tricycle-shaped with a trailing brush.

(10) Drive over a high dune just before losing power. That way when theres a wind storm, enough dust will be blown away to allow the rover to communicate with the satellite. Hopefully, most of the dust will be blown away.

Some of the above ideas were taken from other posters. I believe they could have been used to build a rover that could in theory work forever.

Re:Solar problems

[Anonymous Coward]

use a polonium source same as is used in anti-static brushes. works _perfectly_ to neutralize any dust charge. if it's good enough for professional photographers to remove statically charged dust from negatives, it's good enough for this.

This is a clever method, but it requires air to work. As the radiation from the polonium passes through materials, it ionizes them. Because air molecules have a reasonably long mean free path, the ionized air will drift, and will preferentially drift so as to neutralize static charges on the bristles of the brush. Thus the static charge has effectively been transferred to the air.

Mars does have some atmosphere, but it is considerably thinner than Earth's. You may be able to do the same trick, but you may need to use a strong source.

The other problem is: it seems that these brushes use polonium-210, which has a half-life of only 138 days. [[But on the other hand, it may be that a lot of the constraints that go into choosing which element & isotope to use (toxicity, cost, etc.) would not apply to a Mars mission.]]

Re:Solar problems

[torpor]

Umm... whatever dust is stuck to the rover, has a charge and is using it to stick to the rover.

Re:Solar problems

[torpor]

films that can be peeled off

Films that can be peeled ... implies they are sticking ... so what is the mechanism by which the film is sticking to the arrays and providing a seal? Is it electrostatic charge, like it is with saran wrap, or is it chemistry? mechanics?

i imagine this is just too complicated a problem to solve, in light of the fact that other components of the rover - such as the battery - have a limited shelf-life, anyway ...

Re:Solar problems

[IgnoramusMaximus]

i imagine this is just too complicated a problem to solve..

Just one coat of some sort of film would double the lifespan of the solar arrays. I am not sure what the battery situation is like, but it seems at the moment that the panels will go first. As to the film type, thats just one of the ideas. But one could imagine many systems, and if we are talking one coat, it could be just plain mechanical tension or even opaque (so that it does not need to be too exotic) adhesive between the individual panel elements.

Re:Solar problems

[LooseChanj]

It's a lot harder than you'd think.

Re:Solar problems

[torpor]

You think there isn't already a protective coating on those solar panels? What if, in fact, the life of the solar panels is already twice what it should be, due to some substance?

That's the problem with you dialectic materialist types ... always analysing reactions, not cause.

Re:Solar problems

[rijrunner]

The problem here is that the martian dust is only partially understood. The particles are very small.

The evidence right now is that the particles would actually act as an abrasive on the surface of the solar panel. So, this process would actual act the same way as someone dragging sandpaper across the surface of the panels.

Re:Solar problems

[Dun Malg]

Don't forget that you have to pack all of this onto the rover and fold up the panels.

Implement one of these in each fixed panel, not in the panels as a whole.

Another minor problem: this mechanism must be located the width of the panel away from the edge of the panel, i.e. any closer and it wouldn't be able to peel the layer off completely. Imagine, if you will, such a panel sitting before you with the film on it. Grab a corner of the film and attempt to remove it by pulling in a straight line, without letting go, and without moving your hand beyond the edge of the panel. See the problem? The panels, being the largest objects on the rover, would then require some sort of extended outrigger device beyond the panels to hold the reel that pulls the wire. Not an effective solution.

Re:Solar problems

[i8a4re]

Vibrator probably would not be destructive. Think about the vibrations of launch, rentry, and landing on Mars. Do you think a little vibration motor would do any amount of serious damage???

Re:Solar problems

[Anonymous Coward]

F1 drivers don't reach up there to rip them off. They push a button on the steering wheel.

Re:Solar problems

[IgnoramusMaximus]

You think there isn't already a protective coating on those solar panels..

If it were and was actually working, the dust wouldnt be sticking to it. Tere was quite a bit of discussion about this back before launch when the Sojourner data came in. Its just some weird half-assed NASA management style cost analysis (or politics) that resulted in no protection against dust in the MER rovers. Trust me, next one will have something because a lot of engineering types are raising hell about this. This is the same sort of crap that happens with clockwork regularity at NASA, engineers know about a problem, propose solutions and managers shoot them down not for technical but political or personal reasons. Its the single one thing that has been holding NASA back for 30 years.

Re:Solar problems

[IgnoramusMaximus]

The evidence right now is that the particles would actually act as an abrasive on the surface of the solar panel

You should try it. Take finest grain stuff you can find and put in on a piece of shiny metal (has to be conductive, protection against static charge). And then use a very soft brush on it with minimal pressure. See how much abrasion you get. Noone is talking about a 20lb spring loaded brush with stiff bristles. Think dusters the maids use.

You can also modify this idea by sticking a small compressed gas cannister and pumping compressed gas into the hollow arm and instead of the bristles have gas jets. But thats just makes it more complicated and I dont think it would be needed.

Not to mention all those other ways people brought up, involving peelable films and what have you.

I find all these "Oooh! The martian dust is like super space dust, dude! Magic! Its like nothing anyone has ever seen before!" protestations just ridiculous. Its just dumb dirt in fine grain form in thin athmosphere. Thats it. It even has the same chemical composition as much of the dirt on Earth. The only thing that complicates matters is cold, but one can wait for the noon when temperatures are reasonable to perform any cleaning operations.

Re:Solar problems

[IgnoramusMaximus]

Vibrator probably would not be destructive. Think about the vibrations of launch, rentry, and landing on Mars. Do you think a little vibration motor would do any amount of serious damage???

I dont really know, I was thinking that during launch the whole shebang is tightly packed and forms a solid, stiff one-piece item. When the panels are opened in working position, the vibrations would be spread out through the whole structure causing various types of oscillations. But again, I dont know, it might be nothing of consequence so the system might work. Its just another idea to add to the many already proposed and it just underlines the fact that something went wrong again at NASA.

Re:Solar problems

[rijrunner]

The solar panels are not metallic on their sunward surface.

Re:Solar problems

[IgnoramusMaximus]

The solar panels are not metallic on their sunward surface.

No they arent but they should be coated with a conductive layer to prevent static charges from making the dust cling. That is what I tried to "simulate" by mentioning shiny metal. You can try glass of course but it would not be accurate either since it would make the dust stick more then a conductive surface would.

Re:Solar problems

[rijrunner]

Right.. now.. 3 guesses what the solar panels are using for cover..

Look, the things are built with a projected 30 day lifespan. With a deposition rate of 0.33% per day and with some basic oversizing, it isn't worth the effort to try to squeeze an extra design element into this.

Re:Solar problems

[IgnoramusMaximus]

Look, the things are built with a projected 30 day lifespan

No. 90 days supposedly, according to NASA. But at the rate at which the things are going, the available power will dwindle to the point of beinhg near unuseable well before then.

Re:Solar problems

[Angry Toad]

What about a fluffy feather duster? I have yet to see any electrostatically charged dust problems that a feather duster can't solve.

I'm only half joking.

Re:Solar problems

[barakn]

Except that you now need oversize solar panels because each layer of plastic is reflecting or absorbing some of the light.

Re:Solar problems

[Joey7F]

Flamebait? Wow fantastic...that's what I get for responding to trolls...

Re:Solar problems

[torpor]

The MER's rated (read: warrantied, thus, insured) lifetime is less than the duration of time the solar panels will last, anyway.

I imagine that spending a few hundred thousand bucks on devices designed to keep the panels clean, when in fact the MER's operational lifetime is determined by how long NASA can afford to keep paying the insurance premiums, would've been considered an expensive over-run ... and in the eyes of some government auditors, a waste of taxpayer money.

I understand that there's an engineering solution. I bet that the solar panels are not considered a problem because the insurance will run out, anyway ...

Re:Solar problems

[IgnoramusMaximus]

... by how long NASA can afford to keep paying the insurance premiums ...

Now you got me shocked! You mean to tell me they actually insured the thing?! This is insane! The insurance premium would be like 80% of the cost of the mission! I mean what nutcase insurance firm would insure them for less! I find it hard to believe.

If this is true, that would mean the NASA managment are orders of magnitude stupider then I previously believed and their only objective is to spread taxpayers money to corporate interests (I always thought they were just monumentally bureaucratic).

Re:Solar problems

[torpor]

hold on ... i'm no expert on this, so it could all be wrong. but i've heard that all missions must have insurance ... for the very reason that if something goes wrong, taxpayers don't have to keep fronting the bill to pay the rest of the program costs.

i.e. its insured so that, in case of failure or problems, taxpayers don't have to pay for it...

Re:Solar problems

[IgnoramusMaximus]

but i've heard that all missions must have insurance

No can do. The insurance premiums are directly proportional to risks. Interstellar missions are as risky as it gets and the costs are huge so the insurance premiums would have to reflect that. It would be cheaper to send 3 or even 4 rovers then to pay the premiums. If they do pay the insurance its just a scam to feed some government pork to favourite corporate pals and it would nearly double the cost of the program. The insurance companies are in it for profit and so they would make sure that premiums are more then payouts. Insurance only works in your favour if the number of insured people is huge and each person has a relatively low chance of needing a payout. The premiums are then relatively very small and you are protected from a disaster. The NASA missions are the exact opposite of this.

Re:Solar problems

[torpor]

I know how insurance works. I'm telling you, the MER program pays insurance.

Re:Solar problems

[IgnoramusMaximus]

I'm telling you, the MER program pays insurance.

If so, that means a bunch of corrupted dumbasses are running the show and any successes NASA has should be considered miracles. Paying insurance on space programs is like throwing money away by the bucket. It means that in addition to idiotic boondoggles and influence peddling politics there is outright thievery going on to the tune of 40% of the various program's budgets. I am far from being a proponent of privatisation of all government programs but I must admit that this would be a shining example of why NASA should be disbanded or converted to a small advisory organization and space exploration driven by payments on delivery of results. No results = no money.

Re:Solar problems

[Anonymous Coward]

The martian dust in question is magic space dirt. It's so small that it actually bonds to the surface of the solar panels. You can't scrub it off. The only solution is to remove the layers that it has bonded to. It's not like having a little French Maid martion rover robot up there with a feather duster would fix the problem.

Re:Solar problems

[Thuktun]

Say, a step motor and some mechanical jiggery-pokery ending with a stiff wire, a hook on its end, the layers would have tabs with holes in them to pull at.

And you could guarantee this would work millions of miles in a hostile low-pressure, low-temperature environment?

Or.. a glue between layers that deteriorates on contact with Martian athmosphere and so the layers will peel off after a fixed (based on chemistry) time.

What, a molting rover?

I mean, give me a break, those took less then 10 seconds to come up with [...]

And that time and attention to detail show, believe me.

Re:Solar problems

[IgnoramusMaximus]

And you could guarantee this would work millions of miles in a hostile low-pressure, low-temperature environment?

Not any less then all the other mechanisms composed of multiple motors, gears and joints that already are installed there.

What, a molting rover?

And why not? You get the film to have a natural tendency to roll itself (like many films do) and you have a simple and quite effective system modelled after mother nature. One layer off = double the lifetime of the panels.

Re:Solar problems

[Anonymous Coward]

I meta-modded it unfair if that makes you feel any better.

ACPI

[compbrain]

"The hack works by reducing the power supply to a poorly functioning switch."
You know, they could just tell the rover to use its ACPI functionality and go into standby and spin down its hard disks....

Re:ACPI

[Anonymous Coward]

that doesn't even make sense. stop trying to sound smart.

Re:ACPI

[Anonymous Coward]

Way to rain on his parade.

Re:ACPI

[dzym]

Except ACPI doesn't work properly on anything but Windows.

Nice try.

Re:ACPI

[Anonymous Coward]

Doesn't the rover use linux? :P

Re:ACPI

[Zaiff Urgulbunger]

Do the rovers have hard disks? I've not heard any mention of disks during any tech. reports... only volatile and flash memory.

Fan

[RetroGeek]

Is there some reason why these rovers do not have a fan to blow away the accumutating dust on the solar panels?

The weight penalty should be offset by being able to work longer.

Or is the dust sticky? Maybe something akin to a wiper?

Re:Fan

[goon america]

Doesn't one of their robot arms have a brush device for brushing off rocks? Couldn't they use that?

Re:Fan

[RetroGeek]

Doesn't one of their robot arms have a brush device for brushing off rocks?

The ONE robot arm cannot articulate to a position to reach the panels (it is mounted underneath). Also, the brush is made of wire. Not something you would want rubbing against a solar panel.

Re:Fan

[deglr6328]

a fan would be overly complicated and would draw too much extra power at 1% of Earth's air pressure. Why not just add peel away layers (like a cleanroom tacky mat) of transparent plastic to the panels? A tiny motor would be enough to reveal a new layer now and then. It's hard to believe they didn't try to think of something like this or simply didn't care about the dust problem.

Re:Fan

[Anonymous Coward]

You know I read this and was thinking about that little itch right in the hard-to-get-to place in the middle of my back and I thought ... backscratcher. You could just put a little wiper blade on a stick and, viola, instant solar panel backscratcher!

Re:Fan

[Anonymous Coward]

The brush is also made of metal.

Wiping the dust off of high-end solar panels with a wire brush is really not a very good idea at all.

Re:Fan

[DynaSoar]

RetroGeek (206522) sez: "Is there some reason why these rovers do not have a fan to blow away the accumutating dust on the solar panels?"

Lack of air mass. A fan on Mars would be only 1% the efficiency of the same fan on Earth, because there's that much less air. Plus then you're using more power and using up the batteries, to not much effect.

I would have suggested an electrostatic charger, like the old Diskwasher Zerostat, for removing the charge from vinyl LPs, making them easier to clean.

Re:Fan

[Anonymous Coward]

If a post contains information simillar to other posts on the same article it is NOT REDUNDANT IF IT WAS MADE BEFORE ALL THE OTHER POSTS! If you're going to mod things redundant at least check the posting time.

Re:Fan

[Mixel]

I suspect that in addition to absense of arms that can reach solar panels, the brushing effect will cause the dust to scratch the solar panels. Also the dust might be so fine that a brush may not make much difference.

I'm not very well informed on whether they can be made scratch resistant material, can anyone comment on that?

Re:Fan

[Senjutsu]

As others have said, even if the arm could reach, the brush is metal (read: scratchy).

But even if it was a soft cloth brush, the problem with the dust is it's electrostatically charged, and rubbing a cloth against those panels repeatedly isn't exactly going to decrease the dust attraction.

Re:Fan

[heptapod]

E.G. Any at all

There's plenty of atmosphere on Mars. Just because it averages about 6mbar compared to 1bar on Earth doesn't mean there isn't enough. What do you think perpetuates those enormous dust storms way over there? Kittens?

Re:Fan

[RetroGeek]

That depends on the materials. Some material combinations increase electrostatic charge, while other combinations do not.

Um, don't ask me which. I remember the basics, not the details on this.

Re:Fan

[Anonymous Coward]

A pressure differential will always cause wind. You create a pressure differential with a fan (Bernoulli's Law). Of course since the density of the air on Mars is incrediblly sparse, the fan would have to operate at incredible speeds to create any real pressure difference (and of couse it can't pull a differential greater than 0 barr, so the maximum delta-P would be about 12 mbarr). Additionally since mass flow rate is propertional to the square root of density times the difference in pressure, not much air would be hitting the solar panels anyways. Without much hitting, there wouldn't be much recoil action and the dust would just sit there and laugh. Yes, like kittens.

Re:Fan

[frdmfghtr]

My guess is that the thin atmosphere would prevent any sort of blowing as such...the atmosphere is about a tenth of what it is on earth, so you would need a pretty big fam to get anywhere near the pressure needed to blow the dust clinging to the panels away.

Besides, as has been pointed out, any solution adds power requirements, weight, and complexity/points of failure. Does the extra power provided by clean solar panels outweight the added risk of equipment failure?

Re:Fan

[madpierre]

I wondered why they didn't use a wind generator as a
power source until I did a calculation:

Windmill power output is P ~ 0.5 pAV^3 Watt

V = wind velocity m/s
A = cross section (assume 1 m2)
p = atmospheric density kg/m3 (~0.02 for mars)

Plugging in suitable numbers for the Martian environment:

Ek = (0.02 x 3.5^3)/2 ~ 0.43 Watts

Assuming a generous 30% efficiency gives:

Power output ~ 0.13 Watt

Not an awful lot. Even in a storm with wind velocity ~ 15 m/s
you're only looking at about 10 Watts output, and that's
assuming the dust doesn't clog up the wind generator.

So solar or nuclear energy seem to be the way to go.

What no Roomba?

[rodney dill]

You would think they would have installed some mechanism to clean the dust off.

Re:What no Roomba?

[AndroidCat]

They should have brought some change for Martian squeegee kids.

Re:What no Roomba?

[GrassyKnowl]

Tilt solar panels slightly then vibrate the particles off the panel.

Re:Java problems?

[Anonymous Coward]

The problem was probably caused by some incompatibility in the Java system

Repeat after me.

There is NO Java on the rovers. Java is used on the ground to process the results.

Idiot. Enough has been posted on this site about where Java is being used.

Was panel was sticky ?

[dapyx]

Or is the dust sticky?

Actually it was revealed that the panel was sticky. The NASA engineers don't want to discuss about the source of stickiness.

Difficulties in planning space missions

[nicnak]

The dust problem is just indicitave of how difficult it is to plan such a complex mission like going to Mars. Until we do this a few more times and figure out a few more things, a manned mission will have to wait.

Re:Difficulties in planning space missions

[Gossy]

Um, I seem to recall they knew about dust problems well before they launched. This isn't something that has surprised the engineers. I remember that was the main reason they said they were planning for a 90 day mission, since beyond that point the cells wouldn't charge enough due to the dust.

I've also seen on SpaceFlight Now reports that projections show they will be probably be able to run both rovers well beyond the initially planned 90 days, so they're looking into plans for extended missions now.

However, like others on the thread have wondered, why not devise something to remove the dust? I'm sure there must be a good reason why they didn't do something - I can't imagine the NASA engineers simply didn't think about this.

Re:Difficulties in planning space missions

[stonebeat.org]

if we send men to Mars, hopefully they are wise enuff to get out of the rover (in space suits) and clean the solar panels. ;)

Re:Difficulties in planning space missions

[BeerCat]

Until we do this a few more times and figure out a few more things, a manned mission will have to wait.

Excpet that with a manned misison, a quick way to wipe the solar panels would have been worked out at least as fast as the recent /. posts.
The more remote missions there are, the more the "just one more remote mission" feeling will accrue. If Apollo 11 had been a remote mission, the Eagle would have crashed, because of a rock in the (automated) landing zone. As it was, Armstrong did a quick manual burn to hop over the bad area, and landed safely (with fuel reserves probably below what an automated system would have worked well with)
Therefore, while the experience gained from a remote mission is valualble, it is no replcament for "hands on"

Re:Difficulties in planning space missions

[tealover]

Actually, this is justification for having women accompany the men to mars. ;>)

Re:Difficulties in planning space missions

[Anonymous Coward]

+7, Funny

Re:Java problems?

[KewlPC]

Java is only used on the ground. They'd be stupid to use it in the flight software.

That isn't a slight against Java. It's just that they need real-time software, which can't be had with an interpreted language (even if it is only interpreted from bytecode).

How fast do you think a 20mhz processor could run a Java app?

Blue Skies on Mars???

[vudufixit]

Is this before or after the NASA guys visited the Rekall Corporation?

Re:Blue Skies on Mars???

[vudufixit]

Judging by the moderation, only half the moderators have a sense of humor...

This just in from Saturn

[blamanj]

A nice photo from the Cassini mission.

Re:This just in from Saturn

[deglr6328]

Don't mod the above off-topic, it's still about space! I submitted this story yesterday and it was rejected :( so here is probably the only place you're going to see it and it's really interesting imho! Cassini is entering the final phase of its 7 year journey to saturn and starting now will be sending back images and other measurements at a "rapid and steady pace". In a few months Cassini will enter orbit around Saturn after performing what should be a spectacular ring plane crossing.

Re:This just in from Saturn

[MicroBerto]

I'm having trouble believing this picture... look how perfect it is! It's awe-inspiring that something like that truly exists

Re:This just in from Saturn

[tealover]

What's even more awe-inspiring is the fact that the rings have such a thinness about them, only a couple of meters at best.

To me, Saturn is the most beautiful cosmic creation that I know of. I wonder if there have been any other planets found with rings on them.

Re:This just in from Saturn

[Anonymous Coward]

Most of the gas giants in our solar system have some form of ring system, but none of them are remotely on the scale of Saturn.

Re:This just in from Saturn

[real_smiff]

those photos are so good they look unreal.

mind blowing images should be yet to come..

"After a long 13 year undertaking, and a 3.4 billion kilometer looping voyage across the solar system, it all begins today. Prepare to be amazed."

I am, I am.

Re:This just in from Saturn

[PurpleFloyd]

Any other planet with rings?

Sure, try Jupiter, or mabye Uranus. Of course, they aren't nearly as prominent; Saturn's rings are the only ones that can be easily seen by an amateur observer. However, I'd think that any solar system with gas giants has a decent chance of having ringed planets, as it's really just dust and rocks that have fallen into a stable orbit and haven't globbed together into a moon. We couldn't really directly detect ringed planets around other stars from Earth; the distances are just too great. It would be great, though, to send some sort of interstellar probe to a distant solar system and have our heirs recieve images of a Saturn-like ringed planet.

Seasonal changes

[Dan East]

The blurb fails to mention that seasonal changes on mars are resulting in less sunlight per sol. That is one of the main power issues.

Dan East

Re:Seasonal changes

[RetroGeek]

From the "blurb":

the approach of autumn on the Red Planet

shorter periods of sunlight

Re:Seasonal changes

[Dan East]

I wasn't referring to the articles referenced in the story. I was referring to the Slashdot story itself:

"CNN is reporting that engineers will upload a software hack to decrease the recent power drain plaguing the rover Opportunity. The hack works by reducing the power supply to a poorly functioning switch." p3tersen writes "Opportunity has photographed a blue martian sunset (it's blue because of the optical scattering properties of dust in the martian atmosphere). In other news, the rovers are beginning to experience power supply problems due to the accumulation of dust on their solar panels."

Dan East

Re:Seasonal changes

[Anonymous Coward]

RTFA

Re:Seasonal changes

[Anonymous Coward]

obviously he read more than the blurb to know about the seasonal thing

We can put 2 rovers on Mars...

[Anonymous Coward]

...and fix software problems they're having from a control room on Earth, but we can't figure out how to build the equivalent of a windshield wiper to gently clean the dust off the solar panels?

Re:Java problems?

[mcbridematt]

How fast do you think a 20mhz processor could run a Java app?
Very Slowly. Keep in mind there are native Java Bytecode CPU's out there, but who uses them? My guess is nobody :(.

As nice as it would be...

[r.jimenezz]

...to have the dust wiped off the rover's solar panels, it has many disadvantages. It has been discussed widely here, even by rocket scientists. In short, it is extremely difficult to come up with a "cost-effective" (from several viewpoints) mechanism. An interesting fact is that the cost of operating the entire mission is around US$ 3m a day, and that must also be considered when determining how long these wonderful bots rover through Mars unveiling its mysteries.

Re:As nice as it would be...

[Schemat1c]

An interesting fact is that the cost of operating the entire mission is around US$ 3m a day, and that must also be considered when determining how long these wonderful bots rover through Mars unveiling its mysteries.

That is a good fact. But from my viewpoint the major cost has been the mission failures. All that money spent when a probe goes up in smoke is just completely gone with absolutely no return. It seems to me that 90% of the problem is getting the probe simply to have a successful landing. Since it is obviously so difficult and expensive, once that goal is accomplished the next priority should be robustness and longevity. Divide 3 million by the total cost of all rover failures and I think it would start to make more sense.

Re:As nice as it would be...

[Anonymous Coward]

Roll of Saran Wrap driven by a very slow motor.

Thanks, that'll be $100M.

Re:As nice as it would be...

[Anonymous Coward]

So you're saying that recruiting one of the guys whom we all encounter at one time or another offering to clean our windshield for a couple measly dollars wouldn't be a cost effective solution? Yeah, I know it's silly, but, could you imagine some dude offering to clean off your rover on some other planet for just a couple dollars :)

Re:As nice as it would be...

[Anonymous Coward]

Cough Cough, Bullshit!

The rovers cost $800 million. If you divide that by the 180 day rated life of the rovers you get about $4 million per day (of exploration). But that moneys already paid. If both rovers last 5 more days than the 90 rated, it doesn't mean that they now cost $30 million more. Now take into account that the rovers have been in development (in different stages) since Pathfinder (and before). And also take into account that a significant fraction of the operating cost came from the rocket launch. Finally take into account that once the rovers landed a lot of engineers who designed the craft to operate in interplanetary space and land safely on Mars no longer needed to support the project. I think you'll come to the conclusion that the few operators and scientists remaining probably cost less than $100,000 for any 10 days.

Re:As nice as it would be...

[grozzie2]

An interesting fact is that the cost of operating the entire mission is around US$ 3m a day,

There are 2 types of cost involved in this daily figure, those that are 'out of pocket' and those that are 'just accounting'. Take for example, the DSN time used to retrieve data from the rovers. Yes, it's very expensive I'm sure, those deep space monitoring stations cannot be cheap to build and operate. Every hour they spend pointed at mars collecting data from the MER vehicles is surely tracked, and cost accounted to the MER program, and rightfully so. BUT, it's not like they wouldn't cost anything if they were not pointed at the mars probes, the actual cost of operating the DSN system is for all practical purposes a known and fixed cost, and it's gonna be paid, no matter where they are pointed. This is why I'd call that portion of the daily cost 'just accounting', because the taxpayer is going to foot the bill for the deep space network, regardless of where it's pointed. But, when it's pointed at mars, the mars programs are being accounted as the 'cost', and rightfully so.

While the rovers are on active surface mission, there are a lot of extra people hanging around jpl, and i'm sure most of them are 'rather expensive' to keep on hand. this type of expense is 'out of pocket', it's an expense that wouldn't be happening if the rovers were not on surface mission. My own guess offhand is that the 3 million a day is probably half and half, one half true 'out of pocket' expenses, and the other half just accounting for equipment/personnel that would be on hand anyways, but are currently involved in the MER program. For the sake of easy math tho, I'm gonna suggest 1 mill is 'accounting' and 2 mill is 'real cost'.

Now take a look at the overall value proposition. the entire program is running in the 850 million range, and it's targetted for 2 rovers on surface, for 90 days each. That's 180 science days for a total cost of 850 million, or 4.72 million per active rover science day, as per mission parameters. this was the value proposition of the original mission, and the mission(s) were launched on this basis.

Now that surface operations are in progress, the daily burn rate is 3 million, for 2 rovers on surface. If a million of that is stuff like accounting for dsn time, then 2 million is the actual 'out of pocket' expense, or approximately 1 million per rover science day. this is 21% of the projected overall cost per day of science returned on the original budget.

The up front cost of placing the equipment on the surface of mars has been absorbed, and is planned to amortize over the first 90 days on surface. After 90 days, it becomes a simple value proposition. The 'real cost' of maintaining full operations earthside is 21% of the original budget. In terms of the 'accounting costs' for things like the dsn time, it's the same type of value proposition. The dsn network WILL be kept busy, it's simply a case of determining where there is more value. The 70 meter dish can point out at voyageur and get engineering data from the deep space probe (which will still be there in another 2 months), or it can point at mars, and take advantage of the 'limited time offer' of recieving martian data at 79% discount off the 'full retail' price that was paid for the first 90 days of surface time.

This is a large project, with lots of accounting involved, and surely there's more than its fair share of 'pork' buried in the 850 million price tag. BUT, it's real right now, and the real cost of retrieving a day of data from a single rover is in the range of $1 million. Considering the 'full retail' price for that runs 4.72 million after you amortize in all the launch costs etc, this is one time when a significant budget overrun due to 'extended surface time' is an absolute bargain.

This is kind of a double edged sword though. A design life of 90 days means there is budget for 90 days of operation. An overrun of 90 days on operational time represents a huge value proposition for

Dust on solar panels issue

[thedillybar]

Every "feature" you add to this thing has its tradeoffs.

1. It's going to weight more.
2. It's another potential failure.
3. IF it fails, it can cause other things to fail (say, for example, a switch sticks ON and it drains the battery)

Not installing a wiper or other device to clear the solar panel wasn't an oversight. They made a (probably) well-informed decision not to install such a device. I think the progress so far is remarkable and should be commended. Hopefully they've learned a lot and can make improvements for the next mission.

Hindsight is always 20/20...

Re:Dust on solar panels issue

[XaosTX]

You forget that you are on Slashdot. We like to complain that someone else isn't as smart as we are.

Re:Dust on solar panels issue

[buffnerd]

I would add that NASA has probably done some marketing studies on what constitutes a "minimum operating window." So long as the rover can operate effectively for at least this long, the cost of the mission would be justified. This means long enough to send back all these cool pictures and enough data to determine if water had existed on Mars. Beyond this window, you reach a point of diminishing returns. My guess is that the solar panels without dust-cleaning gadgets already gives a "good enough" window. If so, it does not make sense to shoulder the additional risks posed by the gadgets. - buffnerd

The Martian Dust

[Chris Tucker]

The big problem is that the dust is so fine, it'd be very difficult to wipe it off with anything akin to a windshield wiper. You might remove the dust, but the grit would scratch the glass, eventually causing enough opacity that the panels would eventually be rendered useless.

One thought I had was to gradually apply a charge to the solar panels and then suddenly apply an opposite charge, causing the dust to be repelled from the surface, to be carried away by the Martian winds.

I've no idea if it would actually work or not, but it seemed an elegant solution that didn't require any moving parts.

Re:The Martian Dust

[Scorillo47]

>>> The big problem is that the dust is so fine, it'd be very difficult to wipe it off with anything akin to a windshield wiper. You might remove the dust, but the grit would scratch the glass, eventually causing enough opacity that the panels would eventually be rendered useless.

Probably using a vaccum would not damage the glass. Although this approach also adds more complexity...

>>> One thought I had was to gradually apply a charge to the solar panels and then suddenly apply an opposite charge, causing the dust to be repelled from the surface, to be carried away by the Martian winds.

Unfortunately this will not work since the electrical charge is not uniformy applied in only one direction on the surface glass. The small irregularities of the surface will cause a variation in the electrical distribution over time - for example a small peak in the glass might be more positively charged compared with inner of a nearly-located scratch. The same thing happens on some dust particles - due to their free movement in the air, their electrical distribution will end up non-uniform as well. So they will end up attracting as magnets - the small peak will attract particles on their negative-charged part, and the scratch will do the same on positively-charged surfaces. Now, since all these materials are good electrical insulators, the non-uniform distribution will stick on for a long time.

Probably what would help is to use a blower that would wipe off the dust with martian air. The blown air needs to be ionized to prevent more electrostatic charge to add up by just blowing. The ionized air will have a weak electrical conductivity which will tend to "shortcut" the charged areas. Now, since the martian air is mostly CO2 this pre-ionization process shouldn't require too high voltages - the energy consumption would be pretty low...

Re:The Martian Dust

[Undefined Parameter]

One thought I had was to gradually apply a charge to the solar panels and then suddenly apply an opposite charge, causing the dust to be repelled from the surface, to be carried away by the Martian winds.

Degauss the solar panels? Brilliant!

~UP

Re:The Martian Dust

[Mixel]

This might be a totally clueless suggestion, but what if the top layer of the solar panel was made from transparent, conducting material? The dust that lands on it would lose charge over time and can then be blown/vibrated off with little effort.

Re:The Martian Dust

[PhotoGuy]

What about a clear roll of thin plastic (or whatver) that comes from a spool, over the panels, onto another spool (which has a motor to draw and spool up the plastic). Requires one motor, and a couple of rotating spools. If the motor failed, it would be no worse than the current situation.

What's the problem with a setup like that? Just too much added weight?

Re:The Martian Dust

[Anonymous Coward]

The sad problem is that solar panels aren't necessary at all. A little nuclear reactor and you're off and running for as long as you want. Not very PC tho.

Re:The Martian Dust

[xyloplax]

Yes. And another point of failure. And another potential power drain if it stuck. I defer to the NASA engineers on this one. I just hope they weren't from the Space Shuttle project.

Re:The Martian Dust

[Anonymous Coward]

a better idea i think would be a small air tank and compressor, with a horizontal extension on the mast of the rover that blows the dust off sections with high pressure air

Blue Sunset is NO Surprise

[Crypto Gnome]

Opportunity has photographed a blue martian sunset

It just plain makes sense, when you think about it.

• Earth
  • Blue Sky
  • Red Sunset
• Mars
  • Red Sky
  • Blue Sunset

Re:Blue Sunset is NO Surprise

[Tablizer]

it just plain makes sense, when you think about it. * Earth o Blue Sky o Red Sunset * Mars o Red Sky o Blue Sunset

Does this mean Martian women have dicks?

Re:Blue Sunset is NO Surprise

[Anonymous Coward]

Red sky in morning, sailors take warning.
Red sky at night, sailors delight.
Red sky at noon, sailors should contact NASA immediately.

Re:Blue Sunset is NO Surprise

[Anonymous Coward]

I don't know why this was modded 'funny', you're perfectly right --- it makes perfect sense.

The dust in the Marsian atmosphere scatters red wavelengths more than blue. This makes the sky look red, as the red part of the light passing overhead is scattered --- partly towards your sensor.

When looking at a sunset, the distance the light travels through the atmosphere is maximised, the red part of the light is scattered away, and what is left to reach your sensor is the wavelengths we perceive as blue...

On earth, the opposite holds: the earth's atmosphere scatters blue light (due to the water if my recollection is correct, but don't quote me on this -- other gas molecules may be responsible), making the sky look blue and sunsets red.

Re:Java problems?

[mrtom852]

Some important (I presume) Sun person made the Java on Mars claim at a recent Sun Tech Day. She was quickly corrected by another (more important) Sun guy but it's easy to see how people are getting confused if some Sun sales people are spreading this rubbish.

The whole solar thing...

[Paddyish]

I have a bunch of questions about this stuff.

Why did NASA stray from 'nuclear' batteries, like they've used with the Pioneer, Galileo, Voyager and Cassini missions? Those could power a rover for years.

And what's stopping them from making a way to keep the panels clear? This is what contributed to the end of the Pathfinder mission...What is it about solutions to this problem that make them so difficult to implement?

Wipers add an extra mechanical system to worry about, but what about static fields? Maybe there could be a way to attract the dust to a specific area while keep the the panels clear?

Re:The whole solar thing...

[vbdrummer0]

One suspects that NASA decided to go solar because of the potential disaster to be had if there was a 'mishap' during launch and radioactive material went everywhere in the upper atmosphere. Public protest against putting nuclear fuel on top of a controlled bomb grew steadily over the years, to the point that, if I recall correctly, Cassini hardly got off the ground due to some people protesting it. Probably, there wouldn't be much of a problem, but better safe than sorry (especially when you're funded by taxpayers).

And I'll give the NASA geeks the benefit of the doubt that if there were a reliable and cost-effective wy of cleaning the solar panels, they would have implemented it long ago.

Re:The whole solar thing...

[FrostedWheat]

Why did NASA stray from 'nuclear' batteries, like they've used with the Pioneer, Galileo, Voyager and Cassini missions? Those could power a rover for years.

Most likely because the batteries would out-last the rover itself. It's a complex machine in a hostile environment- something will fairly soon. The solar panels will probably still be operating well after the rovers themselves have failed.

Re:The whole solar thing...

[hcg50a]

Why did NASA stray from 'nuclear' batteries, like they've used with the Pioneer, Galileo, Voyager and Cassini missions?

First of all, those are all non-landing missions to the outer solar system (and beyond).

This mission is a landing mission in the inner solar system, where the sun is bright enough to power the landers.

Second, the use of radioelectric power generators is risky, dangerous and expensive. If there's a less risky, less dangerous and less expensive option, NASA will gladly take it.

Re:The whole solar thing...

[Anonymous Coward]

It's pretty simple.

Do you really think we would give the aliens on Mars nuclear capabilities? How long before they created their own warheads and held the people of planet Earth hostage for 1 million dollars?

Re:The whole solar thing...

[root_42]

>This mission is a landing mission in the inner
> solar system, where the sun is bright enough
> to power the landers.

Yes, but remember that the Viking landers back at the end of the 70s also used nuclear thermoelectric batteries. And they truly operated for *years*.

Re:The whole solar thing...

[FrostedWheat]

something will fairly soon

Er,.. that is, something will break fairly soon.

Sheesh, I've been reading Slashdot to much lately...

Re:The whole solar thing...

[BlueEyes_Austin]

Who is modding these luddites with their ignorant belief RTGs are "dangerous" as insightful????

Clean Solar cells, Do what porn stars do!

[t0qer]

Use a Vibrator! No Really!

I've been reading all the other posts, Every idea from peelable plastic sheets to fans..

Just attatch a vibrating motor to the underside of the solar panels. When it's time for them to get clean, just raise them to a 90 degree angle, turn on the "orgasmotron vibrating motors" and shake the dust off?

Maybe I watch too much pr0n, but I'm sure that would work for the heavier dust. Especially since there was an earlier comment on how the engineers purposefully drive these things over rocks to shake off the larger dust particles.

One more thing, movable solar panels can track the sun, and give better light collecting efficiency than ones that just sit there stationary.

--toq

Re:Clean Solar cells, Do what porn stars do!

[geekoid]

Remember, the energy gained from the cleaning has to be more then the cost of vibrating them.

Re:Clean Solar cells, Do what porn stars do!

[wilfire]

and what he said about moving them, they would have to gain more energy from moving them than would be lost. other wise what would be the point? other than that if these things gave out more energy or they gave more energy for a resionable gain in weight (i have no idea what a reasonable gain in weight would be for a mars lander)

Re:Clean Solar cells, Do what porn stars do!

[jaxdahl]

The problem with that is that the dust on Mars is electrostatically charged -- ever open a box with cling wrap and have it stick to your hand? Tried shaking your hand to get it off? Didn't work? That's the problem. The dust won't simply come off if you vibrate the panels.

Re:Clean Solar cells, Do what porn stars do!

[t0qer]

Well then you could probably do something two fold with existing technology then. I would think though as soon as the dust hits the rover it loses it's statit charge.

Laser printers have a film called a "fusor" that is electrostatically charged. It's green in color, and is built from a heat resistant material.

If it didn't have to be heat proof (like the mars rover panels) it could probably be made clear like a sheet of celophane.

When it goes into cleaning mode, the fusor plastic would start electrostatically charging, also charging the dust particles. Since 2 like polar charges repel, it would repel the dust off the fusor plastic.

Add that in with the vibrating motor, and you have yourself some clean windows.

Re:Clean Solar cells, Do what porn stars do!

[Anonymous Coward]

You wouldn't even need to go to 90 degrees. Two things I would do:

1) drive over some rocks while having a programmed pitch on the rover of say 15-20 degrees. Certainly they can do that if the can dig 4-6 inches with a wheel.

2) Recharge the batteries with the rover at a pitch to give a better angle on the dwindling sunlight. Even a few degrees here could give the rover a few more days (weeks) of use.

agreed

[SweetAndSourJesus]

I'm sure a bunch of half-baked ideas from random yahoos would get them much further than anything their silly engineers could come up with.

Re:agreed

[IgnoramusMaximus]

That is not the point. If a bunch of random yahoos can come up with, on the face of it, at least partially feasible ideas and the engineers in charge dont do anything about it including providing explanation as to why they ignored the issue, you got an impression of incompetence or some hidden agendas.

Re:agreed

[Anonymous Coward]

you got an impression of incompetence or some hidden agendas.

At least you have an appropriate nickname. There are many cool features that NASA engineers would like to have included on the rovers. But at some point, decisions have to be taken on what things will not fly. These decisions are based on many criteria including weight, complexity, cost, etc. There is no hidden agenda here and the missions have been a great testament to the competence of NASA engineers.

Re:agreed

[Anonymous Coward]

Coming up with a solution to the problem "dust accumulates on the solar panels" is not the difficult part. Every idiot engineering student or even lower lifeforms could do that.

The difficult part is thinking of it beforehand.

Re:agreed

[IgnoramusMaximus]

The difficult part is thinking of it beforehand.

Not if the problem was well known beforehand as it was in this case. The dust was even experimentally observed on the Sojourner rover.

Re:agreed

[Anonymous Coward]

Discussion of this article somehow reminds me of all those middle-school science fair "countermeasures" to Star Wars (missile defense, that is).

"Oh, we can just polish the missile, or spin it, or put on a lot of dummy balloons, and there's no way ever that you could defeat our clever scheme."

Here, it's the same sort of half-clever off-the-cuff "solutions" for the solar panels.

Look harder!

[Serious Simon]

Once the robots find water, they could spray it on the solar panels to clean the dust off...

Re:Look harder!

[Anonymous Coward]

Just make the rover stop at the red light of a crowded crossing and have some jobless martian jump out from behind a rock and clean the panels for a couple of bucks.

But at least no more memory problems with Java ;-)

[Anonymous Coward]

Just joking. Java prevents application memory problems by making them all VM memory problems.

Answering myself

[MikeCapone]

I'm by no means an engineer, but I'll try to answer myself. Feel free to point out what I got wrong.

Couldn't they have many transparent protective layers on top the solar panels, so that once the top one becomes dirty it is ejected/separated from the panel (with the dirt)?

Layers on Panels are a Bad Idea

[BigBlockMopar]

A thread attached to a corner of every plastic sheet running diagonally to the opposite corner and an electric motor that activates when the sheet is dirty.
Stack 10 sheets of this and voila, lifetime of the rover multiplied x10.

Conceptually, this is a great idea, except for one problem:

Every layer of $whatever you put on the panels attenuates some of the light striking the panels. The sunlight is also that much dimmer there (at the very least by the inverse square law of distance from the sun, if not also because of atmospheric conditions), so every single watt-hour those things can capture is critical.

Of course, to compensate for the thin film layers, they could have made the solar panels bigger - but that adds launch weight... not to mention the bigger solar panels would make the whole thing more top heavy and likely to tip over due to wind or ground obstructions, meaning you'd want to add size and wheelbase to this thing, meaning you'd need more solar panels... Do we see a vicious circle yet? [grin]

Re:Layers on Panels are a Bad Idea

[r00zky]

Yea, well, but i suppose accumulated dust attenuates way more light than a few thin plastic sheets, no?

And i know what i'm talkin' bout coz i park my car outside and never clean it ;)

Re:Layers on Panels are a Bad Idea

[BigBlockMopar]

Yea, well, but i suppose accumulated dust attenuates way more light than a few thin plastic sheets, no?

Probably after a time, yeah. But the folks at NASA aren't stupid; I'm sure they would have come up with something like that - at least *after* Pathfinder if not before - and decided that cost/benefit analysis didn't make it worthwhile.

(ie. launch weight of the sheets and pulling mechanism, chances of binding and either obscuring a panel or getting caught in the wheels or instruments, chances of it catching the wind like a sail during sheet removal, reduced efficiency of cells over the long run rather than reduced efficiency of cells simply due to dust accumulation toward the end of the mission, etc.)

Re:Layers on Panels are a Bad Idea

[Anonymous Coward]

It's not a solar car.
The ___windshield___ of my gas-powered car gets so full of dust i can't even see the sun through it in a sunny day.

Re:Layers on Panels are a Bad Idea

[BigBlockMopar]

I like the way how you try to appear intelligent and how you capitalize "bad idea" to show what an eleet hax0r you are.

Ah, yes. My AC Fan Club at work again. I've been suspecting for a while that I have a stalker.

The subject line is the title of a diatribe, and in general, as a title, it should be capitalized.

If I wanted to be an "eleet hax0r", I probably would have capitalized the "A", for the full effect of "A Bad Idea". But I didn't.

Furthermore, I'm not gonna be much of a hax0r anyway; I'm an electronics guy, not a programmer. While I can make "Hello, World" in everything from TI BASIC to 680x0 assembly language, my programming style is so much brute force and ignorance that Microsoft keeps on trying to hire me to write Outlook security patches.

So there ya go.

Re:Layers on Panels are a Bad Idea

[Anonymous Coward]

oh.


well...


doh!

Re:Layers on Panels are a Bad Idea

[Anonymous Coward]

yea, i know what u mean, thats exactly what pedestrians say just before i smash 'em to pieces

Re:Layers on Panels are a Bad Idea

[Yorrike]

But the folks at NASA aren't stupid;

They're so incredibly smart, in fact, that they don't even need to convert metric measurements to the archaic system they insist on using.

Go NASA!

Re:Layers on Panels are a Bad Idea

[ozbird]

So use roll of plastic like they use for the in-car cameras in Formula 1 etc. When the exposed section gets dirty, you just wind it off to the waste spool and clean plastic takes its place. Unlike tear-offs, there's only one layer of plastic which minimises light loss. If you had a method to clean the plastic, you could use a continous loop rather than a fixed-length spool.

Because I want one in space

[Papa Legba]

I suggest a solar panel Zamboni! If for no other reason that Zambonis are cool and a space Zamboni would be a magnitude cooler. Imagine the great PR if NASA could send back shots of there Zamboni working on another planet.

Re:Because I want one in space

[Anonymous Coward]

That's it--send a Zamboni into space and watch a hockey game break out...

Sunset

[Lord_Dweomer]

So I'm curious. Lets say we colonized Mars. Because of all the coloring issues surrounding the Martian photographs, could someone please clarify whether we would actually see a blue sky when the sun set? Or is that just some optical properties of the camera?

I have to say though, despite being an extremely short video clip, it is one of the most awe inspiring things I've seen in a while. Think about it. We just viewed a sunset ON ANOTHER PLANET. I can just imagine an art gallery featuring nothing but pictures of sunsets on other planets. As much as I love our planet Earth, I hope the day comes when I'll be able to stand on Mars and watch this for myself. The beauty of the universe is infinite, but every now and then a little piece of that beauty finds its way back to Earth, and we experience this beauty, and smile a little, not quite realizing the magnitude of what has just occured.

Re:Sunset

[FrostedWheat]

Because of all the coloring issues surrounding the Martian photographs, could someone please clarify whether we would actually see a blue sky when the sun set?

The sky would be red as normal, but sometimes there would be a halo of blue sky surrounding the sun. Only sometimes because it depends on the amount of dust in the air. The Pathfinder mission saw sunsets with and without the halo. The halo may also happen during the daytime. There have been no colour pictures of the sun when it's high in the Mars sky.

I remember seeing a program on BBC once that tried to show what sunrise would look like on the different planets. Pritty cool stuff!

mainly because people are ignorant

[xtal]

Why did NASA stray from 'nuclear' batteries

Because the feel-good environmentalists have heart attacks when you mention the word nuclear. The risk is very low and the potential benefits to science are very high. The amount of nuclear material required is not large.

There are some problems with output from nuclear batteries, and I don't claim to be a rocket scientist - but surely it could be made to work.

I'll be laughing my ass off when oil triples in price and people are rioting - we'll see how long the nuclear boogeyman scares people then.

Re:mainly because people are ignorant

[flossie]

Because the feel-good environmentalists have heart attacks when you mention the word nuclear.

Challenger. Columbia. Nuclear?

Re:mainly because people are ignorant

[Anonymous Coward]

RTGs are designed to survive rocket explosions, and even re-entry. They're basically armored warm bricks; the plutonium is present in the form of dioxide ceramic.

In 1968, a SNAP 19-B2 RTG landed in the Pacific after its launch vehicle failed to reach orbit and was destroyed. They fished it out and re-used it on a later mission. Apollo 13's lunar module also had an RTG which re-entered and landed, intact, in the Pacific. No nuclear material was released.

The Challenger explosion generated pressures well under 2000 psi. The theoretical worst case for a hydrogen-oxygen explosion is 2075 psi, with a reflected peak pressure of 5300 psi. RTGs are designed and tested at 19,600 psi.

Shuttle explosions won't cause a release of nuclear material from an RTG. They're not only designed for such failures, they've been tested to survive them, both in the lab and in real life failures.

Re:mainly because people are ignorant

[Tony Hoyle]

It's unlikely you'd get an explosion (you can design them so at the first sign of trouble the control rods shut them down... even something as simple as a spring loaded mechanism).

The problem would be uranium spread over a large area... even that would be mitigated by the fact that a battery maybe a foot across spread over 100 miles isn't going to change the overall radioactivity of the area much.

Re:mainly because people are ignorant

[Anonymous Coward]

I'll be laughing my ass off when oil triples in price and people are rioting

You have a strange sense of humor.

Re:mainly because people are ignorant

[Anonymous Coward]

"The problem would be uranium spread over a large area..."

Try Pu236, the most toxic substance on earth -- fatal at a dose of one microgram. (i.e. a single airborn dust particle.) Billions of fatal doses widely dispersed. Fun fun fun. That said, with Cassini the concern was not with launch but rather with the earth flyby, when an accident could have been energetic enough to rupture the reactor. The next series of rovers (scheduled to use the reactors) will not do the near earth flyby. Still, I expect that NASA has contingency plans. When they discuss the reactors I notice that they revert to very diplomatic language. :)

Re:mainly because people are ignorant

[imsabbel]

Plutonium ISNT the most toxic substance on earth. Its the most toxic base element, but e.g. butolinotoxin has more than 50000times stronger toxic effect.
In fact, the TD50 of Pu236 is compareable to nicotin.

Its not healthy, yes, but it isnt that bad.

Re:mainly because people are ignorant

[Anonymous Coward]

"butolinotoxin has more than 50000times stronger toxic effect [than Pu]."

You mean lethal at 1/50th of a nanogram? Meaning that one gram can kill 50 billion people? You got some proof handy? This I've got to see.

Re:mainly because people are ignorant

[terrymr]

Where does this "most toxic substance on earth" crap keep coming from .. Plutonium is not water soluble so it's not toxic in the conventional sense ... I don't believe there are any reported deaths from eating it ... the main danger comes from inhalation, and then you need very small particles to inhale it.

Re:mainly because people are ignorant

[Anonymous Coward]

People like to conflate measures of "toxicity" to make it sound more scary.

Pu238 is an alpha emitter, which means you can stop the radiation with a sheet of paper or a few inches of air. If, however, you happen to inhale that Pu238, and it just happens to be of just the right particle size, it can lodge in your lungs. At that point, you have an increased risk of various cancers. In this one particular application, Pu238 is fairly dangerous.

Chemically, it's not particularly toxic.

The odds of actually getting particles of just the right size distributed world-wide and lodged one particle per human lung are preposterously low, of course. It's sort of like expecting all the air to rush out of your house and suffocate you because all the molecules just happened to move the same way.

The analysis for Cassini concluded that even in a worst case scenario, stipulating all the various improbabilities needed to release any Pu02 in the first place, an area of about 7 square miles would be affected in excess of existing EPA regulations. Assuming all of the Pu affected people on land, the effect would be about 1 extra millirem over 50 years, a period in which you normally get about 15,000 mrem. Excess cancer deaths would have been about 120 (and before you say something like "even one life is too many", please check some OSHA statistics for accidental causes of death). I'll neglect the argument about the effect of extremely low doses of radiation here; there's some evidence such might even be beneficial. But we'll stick with the 120 number assuming a linear effect far below the threshold at which anyone has been able to measure an effect.

Re:mainly because people are ignorant

[Anonymous Coward]

"Radioactivity and Health-A History" by J Newell Stannard, U.S. Department of Energy, Pacific Northwest Laboratories, Battelle Memorial Institute, 1988, pg 368.

Acute Toxicity of Plutonium Compared to Supertoxics (LD50)

Botulinus Toxin A 5X10E-6 ug/kg
Crystalline Botulinus 7X10E-9 ug/kg
Diptheria Toxin...... 1X10E-4 ug/kg
Bufotoxin............ 390 ug/kg
Curare............... 500 ug/kg
Strychnine........... 500 ug/kg
Potassium Cyanide.. 300 ug/l
Hydrogen Cyanide... 1000 ug/kg
Methyl Mercury..... 7000 ug/kg
Arsenic Trioxide..1000000 ug/kg

Plutonium....... 300-1400 ug/kg

And, just for the heck of it:
Nicotine........ 810 ug/kg

Re:mainly because people are ignorant

[ghjm]

Oil was three times its current price in the 80s and nobody rioted then. There's actually a good argument to be made that higher oil prices would benefit the world economy. With oil prices depressed as they are today, the rich and energy-hungry industrialized nations get a free pass at the expense of the poor but resource-laden third world. Increase oil prices, and you transfer more money to the people who need it.

Or at least, you transfer more money to violent warlords who live in the same towns as the people who need it. Either way, the impact to the industrialized world will be limited to a few 'fuel surcharges' when you ship a package or buy a plane ticket. (And of course this presents the airline industry with a desparately needed opportunity for profiteering.)

The real issue with the nuclear boogeyman is that people will continue to oppose building nuclear plants even as they watch first-hand while coal and oil mining strip the land for miles around.

Re:mainly because people are ignorant

[Anonymous Coward]

Hey I can do a web search too. I can even provide attribution:

http://www.vanderbilt.edu/radsafe/9406/msg00038. ht ml

regarding Don Jordan's posting:

That LD-50 for botulinus toxin is wrong. It's usually considered to be
around 0.00001 mg/kg in rodents, i.e., 0.01 ug/kg , not e-9 ug/kg. That's
still super-toxic. By comparison, the LD-50 for dioxin, often called the
"most toxic small molecule," is 100-fold greater at around 0.001 mg/kg in
rodents. But as pointed out, we're comparing apples and oranges since acute
lethality isn't really the issue with plutonium (or dioxin).

Joshua Hamilton Ph.D.
Dept. Pharmacology & Toxicology
Dartmouth Medical School

Re:mainly because people are ignorant

[Anonymous Coward]

"The Challenger explosion generated pressures well under 2000 psi. The theoretical worst case for a hydrogen-oxygen explosion is 2075 psi, with a reflected peak pressure of 5300 psi. RTGs are designed and tested at 19,600 psi."

Yes, very nice theoretical data, but it doesn't take into account of sharpnel hitting the RTG.
Remember using similar statistical data the US military calculated that the M1 tank was invincible against RPG attacks, yet the Iraqis managed to destroy one in last the war.

Re:mainly because people are ignorant

[Anonymous Coward]

You mean lethal at 1/50th of a nanogram? Meaning that one gram can kill 50 billion people? You got some proof handy? This I've got to see.

Uh oh... The Trinity test back in 1945 used a 6.17 kg plutonium core, of which about 21% fissioned...

This means that about 4.87 kg of plutonium was dispersed into the atmosphere -- according to you, this is enough to kill 243 trillion people through plutonium toxicity! (Note: this includes only direct toxicity -- not increased risk of cancer.)

Thanks for the heads up! Looks like I'd better get myself to a mineshaft right quick!

Re:mainly because people are ignorant

[Miamicanes]

You're assuming it's possible to neatly separate one gram into 50 billion discrete 1/50th nanogram doses and distribute one of them to each of the 50 billion people. In reality, a relatively small number of people would absorb individually massive (relative to 1/50th nanogram) doses and bear the brunt of it.

No, it wouldn't be a Happy Ending, but relative to the global impact of, say, an asteroid landing in the Pacific ocean somewhere around Hawaii, it would be pretty minor by comparison.

Re:mainly because people are ignorant

[Dun Malg]

Yes, very nice theoretical data, but it doesn't take into account of sharpnel hitting the RTG.

Shrapnel propelled by an overpressure of 5300psi isn't going to hurt a a hardened unit than can take 19,600psi. The physics just aren't there.

Remember using similar statistical data the US military calculated that the M1 tank was invincible against RPG attacks, yet the Iraqis managed to destroy one in last the war.

I seriously doubt you are privy to the statistical data for either case you mention, and besides, what possible similarity could they have anyway? Nobody in the military ever declared the M-1 Abrams "invincible" to RPG hits. The one incident in Iraq to which you refer was a hit to the engine compartment that resulted in immobilization, not destruction. The only other incident involved a one-in-a-million lucky shot to the relatively thin armor of its armpit joint, the area above the tracks and beneath the deck. This area is covered by skirt armor and is so small that it can't be effectively aimed for, only hit by blind luck. Furthermore, it wasn't an conventional RPG-7 hit in that case-- it was some as-yet-undetermined warhead. Furthermore, in neither cas was the crew of either vehicle injured in any serious way. This is the entire point of the armor in the first place-- crew protection.

Re:mainly because people are ignorant

[Anonymous Coward]

"Shrapnel propelled by an overpressure of 5300psi isn't going to hurt a a hardened unit than can take 19,600psi. The physics just aren't there."

Presumably the rating you are quoting is of the pressure of the gas within the explosion area.
This has nothing to do with high velocity sharpnel
propelled by several tonnes of exploding LOX and hydrogen. There is no hard data showing that a RPG can survive a launch explosion. The only way to know for sure is to blow up several RPGs and see how many survive and as far as I know nobody has done this.

Re:Java problems?

[r.jimenezz]

I think the main issue with Java is not the processor, but several other qualities that, while highly desirable for a general purpose language, are unacceptable for real-time systems (garbage collection is one of them).

This is why there's been work for a real-time version of Java for a number of years now (see here). Incidentally this is what kicked of the JCP (it's JSR-001 :)), and according to my Concurrent and Realtime Programming in Java lecturer (Andy Wellings, who sits in the Technical Interpretation Committee for this JSR), NASA is quite interested in this as an option for its future missions to Mars.

Compressed Gas to blow the dust off?

[Anonymous Coward]

Why not just install a little compressed gas canister and blow the panels clear of dust?

It might not be 100% effective, but surely it could get most of the dust off? There is already a manipulator arm on the robot... maybe add a little hose & nozzle attachment to it? Dunno...

And if there's an issue of contaminating the martian environment... cant you sterilize the gas? Is introducing any type of gas into the martian atmosphere an issue?

Re:Compressed Gas to blow the dust off?

[evanbd]

My understanding is that a variety of dust removal techniques were considered. The final decision was that an effective dust removal aparatus could be added, at the cost of any one of the instruments. The scientists decided limited life with more instruments was more useful, and so the dust removal system was left off.

Re:Java problems?

[nehril]

this is slightly OT, but "real-time" in engineering circles does not mean "really fast." it means that there is a guaranteed response from the system within an specified actual time frame.

i.e. I need a real-time OS & software stack if my rocket control algorithm needs the data from, say, a serial port altimiter within the next 20 milliseconds or else. if you cant get the data within the specified timeframe then the results are useless. the system will not accept requests that it cannot "guarantee" to fulfil from a system resource standpoint. (you have to watch your multitasking, swapping and other kernel-level tasks to achieve this)

so you could have a 20 mhz "real-time" system, as long as it's response was guaranteed by the OS within parameters for what you are doing (and you would program with those guaranteed response times in mind.) Conversely, a 20 Ghz system may not qualify for real time, if the OS pre-empts your rocket control task and decides to swap for a few milliseconds too long, or context switches to another thread just when you needed to adjust a control surface...

when you hear about people hacking linux for real-time work, they are not making it go faster (though that's always nice), they're making it work predictable.

One word

[geekoid]

Hippies

No power supply problem, just less power

[hcg50a]

"In other news, the rovers are beginning to experience power supply problems due to the accumulation of dust on their solar panels"

This makes things sound worse than they actually are. They are not beginning to experience power supply problems -- they are simply getting less power than they were when it first landed, and they are taking some steps to operate more efficiently.

From SpaceFlightNow, in the report for THURSDAY, FEBRUARY 26, 2004 2215 GMT (5:15 p.m. EST):

"The amount of power Opportunity is able to generate continues to dwindle due to the decreasing amount of sunlight (energy) reaching the solar panels during the Martian seasonal transition to winter."

From the Reuters report:

"NASA's two robotic rovers on Mars have begun scaling back their working hours as the approach of autumn on the Red Planet and dust on their solar panels slowly chokes off their power supplies, a NASA official said on Friday."

What the NASA official (Richard Cook) actually said was: "The vehicle is continuing to perform fine but we are starting to modify our daily process to respond to the decreasing power."

Both the dust accumulation and the decrease of sunlight were anticipated. The lifetime (designed to be 90 days) of each Rover is determined when the batteries can no longer be charged enough to survive the cold nights. Spirit is already 54 days into its 90-day "death sentence".

I'm thinking

[geekoid]

at about 20mhz

Re:Java problems?

[Anonymous Coward]

This thing runs java quite nicely with an 8051 variant running @ 20Mhz http://www.ibutton.com/TINI/

Concerning charged particles...

[dirt_puppy]

You can't blow them off with opposite charge easily. These particles stick to the (non-conducting) surface probably because of Influence. If the surface would be conducting they wouldn't stick because they would get discharged. This is similar to the dust particles that adhere to CRT screens, just here its the screen thats charged (by constant electron bombardement) and the dust particles get influenced. The fact that the surface is non-conducting will also hinder you bringing any kind of charge to it. Another problem is that the charge might be randomly generated and so half positive and half negative, so you could only blow off half of the dust. There is a possibility of making transparent surfaces conducting (coating them with metal films), but this reduces transparency quite a bit, and I suppose the mechanical properties of a metal film are far inferior to whatever they used (you want this surface to be hard).

Re:Concerning charged particles...

[IgnoramusMaximus]

but this reduces transparency quite a bit,

I am not sure you realize that all of the LCD displays feature transparent conductive surfaces for the electrodes. Hell, most of them have entire circuits that are transparent (TFT = Thin Film Transistor). There are chemicals that are for all practical purposes transparent and are conductive.

Re:Concerning charged particles...

[dirt_puppy]

I know this, but I think even in these apparently completely transparent films the transparencies are in the 90% range. The eye is pretty insensitive to brightness changes, but in a mars rover, 10% loss would probably be inacceptable

Also from space: "Humble" telescope

[AndroidCat]

Might as well toss some more space news in. No pictures yet alas. Tiny telescope exceeds high hopes May detect clouds on distant worlds.

It's a neat little $10 million 50 kilo unit. The best part is that a software upgrade improved the stability 10x. Hopefully there'll be some pictures soon.

Obligatory reference

[CrystalFalcon]

/me looks at clip and exclaims,

"Blue sky on Mars... is this a new one?"

Re:Obligatory reference

[Anonymous Coward]

/me looks at clip and exclaims,

Geez, where do you think you are? IRC? Go wank somewhere else.

drive the damn thing through the ghetto

[Anonymous Coward]

I'm sure some guy with a squeegee will jump on it in no time.

Astronomy Picture of the Day

[rodney dill]

The APOD site had this picture of a "named" rock a couple of days ago.

electrostatic dust

[dpilot]

Arthur C. Clarke wrote a story reminiscent of this, set on the moon. Two explorers in a dusty area, and some of the dust sticks to their faceplates. Wiping the dust off builds electrostatic charge, attracting more dust, so they're soon blind.

***SPOILER ALERT*** (and suggestion)

Since rubbing causes static electicity, they rub their faceplates together. One charges one polarity, the other the opposite. So one faceplate comes out even dustier, the other clean. The explorer with the clean faceplate can lead the other back to the vehicle.

Actually I always though static electricity came from rubbing dissimilar materials, so I wouldn't expect rubbing two identical-material faceplates to do squat. But there may be a lesson here. If the primary problem is really electrostatic, might there be some sort of electrostatic solution? (on future rovers) The most extreme would be an ion-wind generator with the 'benign' (dustwise) polarity attached to the panel. Another might be a charged wiper blade. I'm sure there could be other simpler electrostatic-based solutions.

Re:electrostatic dust

[Anonymous Coward]

Larry Niven had a similar story. No rubbing of face plates, the Martians arrived, killed everyone, the end.

Re:Java problems?

[Anonymous Coward]

Pretty fast actually, seeing as it would only be doing something simple, and the processor wouldn't be doing anything else.

It's pronounced Nuk-U-Lar..

[Cpt_Kirks]

I imagine we will see nukes on rovers some day. This whole business tends to go in steps. The last rover was tiny and limited. These rovers are more advanced and bigger. The next one may be a nuke and could travel hundreds of miles instead of a couple of miles (at most, if that far).

Of course, they are also working on gliders, balloons and giant "beach balls" for mars use.

The RAT is not exactly a brush..

[SuperKendall]

RAT is short for "Rock Abrasion Tool", meant to remove the upper layer of a very hard rock.

In the same way you'd not be keen to use a RAT to brush your teeth, you probably would not wish to use the RAT to clean a transparent surface of a solar panel. In fact I think you may have just given some poor engineer at NASA a heart attack just by suggesting the RAT come near the solar panels!

They don't want long life for rovers

[Katz_is_a_moron]

Ok, hear me out.

Cost aside, there most likely is a way to greatly extend the life of a rover.

From the noises NASA has been making, there will be a series of unmanned missions to Mars before an attempt to send humans will be made (I don't necessarily agree with the premise of sending humans to Mars).

NASA has said the limiting factor is power, because of the dust accumulation on the solar panels.

Let's say that the cost of implementing a way to eliminate the dust doubled the cost of the mission (probably would be less). If dust were eliminated, then the rovers could operate until the batteries could not longer hold a sufficient charge to do science.

What I'm getting at here is politics. A solution could be engineered to greatly extend the life of the rovers. But that would result in a reduced number of missions and *less funding*.

Ok, I've removed my tinfoil hat. Comments?

Blue skys on Mars ...

[madpierre]

it's blue because of the optical scattering properties of dust in
the martian atmosphere

That's Scullys Xplanation.
Mulder says different.

Or it's because NASA's mission faking division forgot to photoshop the
images before releasing em. ;)

That's why OUR sky is blue, silly!

[csoto]

Sunlight = full spectrum. The sky really isn't blue...

Much dust and no water [and no oil-petrol]

[Anonymous Coward]

Is it an oasis of bad desert?

open4free

It's called fines, not dust!

[RevAaron]

It's called fines not dust, you insensitive clod!

That's like calling dust gravel, jeeze.

(with apologies to KSR's Red Mars)

The obvious joke

[confused philosopher]

On Soviet Mars, the Pink sunsets are BLUE!

Re:Java problems?

[Anonymous Coward]

I thought the rovers are on Mars with the Martians, now you're saying they are on the Sun with the Sun People?

No_Nukes = Cost * PR^^2

[cmholm]

Some of you may recall that the Viking landers used radioisotope thermoelectric generators (RTG's), the "warm brick" another poster referred to. The landers remained active for up to six years, Viking 1 having been disabled by a boo-boo from mission control. They didn't have to worry much about dust accumulation, and Viking 2 landed at 48deg North, 'way north of the tropical band the MER planners were limited to by solar panels.

So why nukes for Viking, and none for MER A & B?

1) Viking had money. Sure, NASA was getting into a budget hurt locker by the time the missions made it to Mars in '76, but the money was there when it was needed during the planning and construction. The landers got the kitchen sink, and the biggest Titan II launchers then avaiable to get 'em going. By contrast, the MER team had to make sure their package was not much heavier and absolutely no bigger than Pathfinder. The planetary missions are bastard stepchildren to a NASA which is mandated to keep the Space Shuttle and ISS going on an inadequate budget, even if it all went to the manned space program.

2) Three Mile Island, Chernobyl. Hadn't happened yet, so the no nukes crowd was still the wacko fringe during Viking. Compare to the fuss made over Cassini before launch and while making a gravity-assist Earth flyby. "200,000 deaths!" "Dump it in the Sun!" In general, people have mellowed out a bit, but the PR angle makes a good excuse when one doesn't have the money to gold-plate a mission, anyway.

Solar panel in a dust storm?

[im a fucking coward]

Who okay's these stupid ideas at NASA? What dumbass is running the show there now, and how many astronauts did he have to barbecue to float to the top of that bowl?

It's called nuclear power folks, and you can use it to create extremely reliable electric generators with a shelf life on the order of decades, and extend the life of sattelites and roving projectiles for years, not days. Day or night 'til the wheels fall off.

In fact, if you use said nuclear/electric power generators to power ion drives, you can use less than half the propellant to get to [insert planet here].

I don't get it. When did NASA become a jobs program for morons? I mean, morons have to make a living too, but shit, can't we let them execute water fountain projects instead?

Re:Solar panel in a dust storm?

[Anonymous Coward]

The RTGs weight about 100+ pounds each. Each rover weighs 400 pounds each. You're going to have to sacrifice some science instrument to get the RTG into the rover, even if you subtract the weight of the solar arrays. I'm pretty sure the arrays don't weigh 100 pounds.

Re:Solar panel in a dust storm?

[physicsboy500]

This seems to be a good idea... but what happenes when the satelites re-enter the atmosphere at the end of their lifetime...

Either you have radioactive waste hanging in the atmosphere, a third world country with the means to make a couple of dozen warheads, or you have some "dumbass" (in your words) trying to run upkeep missions on several thousand nuclear satelites to keep them safely above the atmosphere.

Re:Java problems?

[brand bendy]

I want to compliment you on a fine explanation of "real-time". A lot of words and phrases like this start to be used incorrectly, especialy when they become buzzwords. Its always nice to see the record set straight.

Don't Knock US/Imperial/SAE Measurements!

[BigBlockMopar]

They're so incredibly smart, in fact, that they don't even need to convert metric measurements to the archaic system they insist on using.

Don't knock US/SAE measurements, there's a good reason they've stayed around.

For scientific analysis, without question, Metric rules.

But when you're actually building and working on things, most of the time a 10% tolerance is good enough. As a result, usually you can stick your thumb across something and say, "Yup, that's an inch - close enough". The base units are more intuitive, although admittedly the interconversion between units is a bitch - but conversions are more common in analysis than construction/maintenance.

My perspective here? Canada went Metric in 1976. I grew up in Metric. I went to school in Metric, fuelled up my cars in Metric, got a set of Metric wrenches when I was a kid, etc. Heck, you wanna know Metric inside and out? Try taking an engineering degree in Canada!

And yet, I know I'm 6'4" tall, 185lbs. I don't know in Metric.

Every time I work on a car, I want to know first, Metric or SAE? (And I don't mean the speedometer, they've all been Metric in Canada since 1976.) Not because I care which wrenches, sockets and feeler gauges I bring, but because I like working on SAE much more.

Why?

I've had more cars with Metric fasteners and specs than I have SAE, and yet, somehow, I can still just put my thumb across a bolt and know, "Hey, that's not 1/2", that's 7/16"!" Why can't I do that with Metric? I sure which I could, especially since I've got more experience with Metric.

Re:Don't Knock US/Imperial/SAE Measurements!

[Kaboom13]

When building a one-off component in the U.S., it is ussually much easier and cheaper to use english measurements instead of metric. The reason being, everything is sold in english units, and metric is usually pretty hard to find unless you order it. In a perfect world, metric would be the better system, but as it is the old english units work better in practice. The most important thing is consistency (which was NASA's problem). Pick a system and stick with it through an entire project and you won't have to worry about it. It's not like converting inches to feet is really all that much more difficult then metric units anyway.

Re:Don't Knock US/Imperial/SAE Measurements!

[BiggerIsBetter]

Don't post your inadequacies as an argument for imperial unit usage. Go and practice some more or something. I've grown up with metric as well, and I *can* tell the difference between a 10mm and 11mm bolt. Usually by sight, but also by touch if it's in an odd location an I can't see it properly. And yes, I'm equally comfortable with SAE, which helps when fitting modern components to old English cars...

Re:Don't Knock US/Imperial/SAE Measurements!

[Anonymous Coward]

Well, it depends on what you grow up with.
Your smallest finger is about 1 cm wide,
If you take a large pace, that's a meter.
Walk 100 paces for a hectometer, 1000 for a kilometer.

A hand-span is roughly 10 cm (1 dm) . A cube of hand-spans is 1 dm^3 = 1 liter.

If everything around you was built using metric units, you can just round off, and that'll be exactly right.

Re:Don't Knock US/Imperial/SAE Measurements!

[Lehk228]

LOL the grandparent wasn't knocking US/SAE measurements.... they were knocking NASA for fucking up a trjectory big time because "oops... that was in meters?..... oh shit"

Re:Don't Knock US/Imperial/SAE Measurements!

[Anonymous Coward]

But when you're actually building and working on things, most of the time a 10% tolerance is good enough.

I humbly apologise to anyone expecting a clever and entertaining response to this comment. It is so staggeringly stupid that I can't possibly begin to think of the right combination of real-life counter-examples, allusions to the acceptability of 10% tolerances in the production of interplanetary craft, or threats of slide-rule beatings to fend off this complete and utter (and probably criminal) idiocy.

If you'll excuse me, I'm off to inform my Engineering 101 professor that my 41% is actually a passing grade.

Why no solution to remove dust

[Dominic_Mazzoni]

A lot of people are discussing ideas to remove dust from solar panels. Something people are forgetting is that there's a downside to having the mission last longer than originally expected: it costs more. JPL designed the rovers to last about 90 days, and NASA gave them enough money to pay the hundreds of engineers and scientists it takes to operate the rovers for 90 days each. They of course have the option of extending the mission for longer than 90 days, but the money to pay for that extension will come right out of NASA's Mars program, which means less money for future Mars missions (including Mars Reconaissance Orbiter 2005, which is already well under way and needs every penny it can get).

Re:Why no solution to remove dust

[/dev/trash]

It's the gummit, they can go into a little more debt.

Re:Java problems?

[KewlPC]

I am aware that real-time does not mean "really fast."

There are many aspects of Java that mean you can't guarantee a response within a certain timeframe. Garbage collection, for example.

My remark about it being an interpreted language just meant that there isn't necessarily a 1:1 instruction translation of the JVM's bytecode, and therefor you can't know beyond a shadow of a doubt that a certain operation will get done in a certain amount of time.

The remark about the 20mhz thing (the CPUs on the two MERs run at 20mhz) had nothing to do with Java not being suitable for real-time applications. Rather, I was just stating that Java would be really slow on such a system.

Compressed air

[DigiShaman]

Why not just use compressed air attached to a moving arm with small holes. Then, just program it to sweep just 1/2 an inch above the panels while providing short bursts of air to blow the dust off.

Sounds simple enough for me. Except, the dynamic change in temperature that the rover has to deal with my cause the air tanks to rupture. So, the amount of PSI you could hold per tank might be limited...thus the amount of times you could clean the solar panels

What?

[Anonymous Coward]

I attended a seminar last week with David Des Marais of NASA Ames reserch center. He noted that, while the panels were covered with dust, the rovers were still maintaining greater than peak power. He specifically stated that the rovers were shunting power because they couldn't store anymore. They suspect that the rovers will far outlive their contracted period.

Re:Java problems?

[nehril]

There are many aspects of Java that mean you can't guarantee a response within a certain timeframe. Garbage collection, for example ... there isn't necessarily a 1:1 instruction translation of the JVM's bytecode, and therefor you can't know beyond a shadow of a doubt that a certain operation will get done in a certain amount of time.

you can get real-time behavior out of an interpreted system, if both the interpreter and underlying operating system are designed for it. For Java, GC and instruction translation just have to have that as a design goal. As a matter of fact: here's some information on real time Java:

"With the recently released Real-Time Specification for Java (RTSJ), developed through the Java Community Process by the Real-Time Expert Group, the real-time embedded software developer will be able to use the Java programming language in applications where predictable/hard real-time behavior is a must."

that being said, java probably would run too slowly for most applications on a 20 mhz cpu. But being interpreted or having GC are orthogonal issues to real-timeness.

meta-lessons of rovers

[wes33]

the rovers have done fantastic work, raising a multitude of fascinating questions.

In fact, isn't it obvious that the questions are coming a lot faster than the answers? The prime lesson of the rovers is the need of a team of human geologists on the spot with a field laboratory.

I would say more than 100 times the capability for way way less than 100 times the cost (that would be 830 million times 100 = 83 billion).

Re:meta-lessons of rovers

[Anonymous Coward]

I agree. How about a project plan that says "to hell with the cost, let's do it properly." Then go ahead and do it.

simple: windshield wipers

[victorvodka]

Hello? How about installing windshield wipers on the solar panels of the next Martian probe? Running out of power because of easil-eliminated dust is just plane STOOOOOPID.

Lean it into the sun

[bluyonder]

They should park it on a slope whenever possible so that the solar panels face into the sun.

Rover Science Reports

[forgetful]

Does anybody have a link to Mars Rover science-in-progress? We are getting all sorts of operations/engineering reports and neat photos, but almost no science reports. What have the spectrometers found? Does the rock chemistry correspond to known minerals on earth or is it new? What ever happened with the briny mud speculations a few days back? I suppose there is a methodical plan to analyze and release papers, but it sure would be fun to at least know the basic composition of those sphericles for coffee break discussion.

Re:Rover Science Reports

[Anonymous Coward]

There have also been no followups on the "surprising" discovery of olivine by Spirit early in the mission. NASA's geologists speculated that the readings must have been made from some rock a millimeter or so below the surface of the soil, not from the soil itself. But there's been not a peep about it since. They've taken lots more measurements since. But did they find olivine in the soil or not?

I attended a talk on this today at Texas A&M

[billatq]

So I just happened to be lucky enough to get front row seats (I work as a sysadmin in the physics department here) to a talk by one of the people on the JPL team that works on the lander, and he mentioned this earlier. It's a bit more than a little hack to the software because it involves changing out the operating system and turning the rover completely off during the night to avoid power drain. What the fellow talking about it mentioned was that there is the possibility that the rover wont actually turn back on after the update, leaving a $400 million piece of junk on the surface of mars.

The reason for the update is needed because there is a heater on the rover that defrosts the probe that allows them to take samples from the rocks and such--which wont turn off anymore. This might not be a problem except that it puts an excess power strain on the rover, meaning that its useful life is greatly diminished. So essentially this hack means turning everything off at night because they can't switch off just the heater.

what about the beagle?

[woohoodonuts]

Or they could just send up another beagle. The wind from it smashing into the ground nearby may blow off some of the dust...

hey... you never know.

Latest Image

[FrostedWheat]

My goodness, not even Mars is beyond the reach of Disney!!

You're right, except its not hidden

[nfabl]

It costs a metric fuck-load to track and drive the rovers like they are now.

I'd say a good 100 million of the budget would be staying at this end to pay for satelite time, man hours, consulting, computation and all kinds of things.

2 Rovers running something like 8 hours a day each, and its not exactly a kid with radio controller at this end.