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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."
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.
NASA should have installed wiper blades on the solar panels.
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?
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I am a programmer. I am paid to produce syntax not grammar. Deal with it.
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?
A nice photo from the Cassini mission.
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
Better known as 318230.
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.
Guaranteed! This comment 100% Anthrax free!
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?
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.
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.
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).
:)), 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.
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
The revolution will not be televised.
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?
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).
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.
The living have better things to do than to continue hating the dead.
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?
"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.
It's called fines not dust, you insensitive clod!
That's like calling dust gravel, jeeze.
(with apologies to KSR's Red Mars)
Working toward a usable PDA environment in the spirit of Newton OS: Dynapad
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!
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?
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