Mars Rover Spirit Down a Wheel

riflemann writes "NASA is reporting that two years into its 90-day mission, Spirit has lost one wheel and is now running on five wheels, dragging the broken wheel. With this reduced mobiity, the rover still needs to make its way to a slope where it can catch enough sun over the Martian winter to keep it operating. 'Even though the rovers are well past their original design life, they still have plenty of capability to conduct outstanding science on Mars.', says project leader Dr. John Callas."

Comments

Tis but a scratch

[Anonymous Coward]

I've had worse.

Re:Tis but a scratch

[metricmusic]

A scratch? Your wheel's off!

We thank thee Lord, that in thy merc-

Re:Tis but a scratch

[buswolley]

Lets all bow our heads for a moment.... for the loss of the sixth wheel.

Re:Tis but a scratch

[SEWilco]

And the fifth wheel seems unnecessary.

Re:Tis but a scratch

[ScrewMaster]

A scratch? Your wheel's off!

Not it's not.

Look!

It's just a thresh wound.

Great...

[Anonymous Coward]

now we have interstellar tricycles?

Re:Great...

[Anonymous Coward]

Dumbass. 5 != 3

Re:Great...

[poopdeville]

RTFBlurb. It's now running on five wheels, and is dragging the sixth.

Re:Great...

[Anonymous Coward]

I really hate being the fifth wheel.

Re:Great...

[Anonymous Coward]

My tricycle had training wheels.

Re:Great...

[Anonymous Coward]

What's your point? a bi-tricycle with a damaged wheel

Re:Great...

[m.lp.ql.m]

Dumbass. 5 != 3

"One... two... five!"
"Three, sir."
"...Three!"

Re:Great...

[Drkdstryer]

Monty Python...

"And with the three wheels..."
"Five wheels sir!"
"FIVE wheels... the rover can keep moving, even though it only has three wheels."
"Five wheels my liege!"

Re:Great...

[SEWilco]

"One... two... five!"

"Profit!"

Not so surprising

[Reverend528]

That's what happens when you only test the wheels for 9 days.

Re:Not so surprising

[slightlyspacey]

What do you expect? The rover has lasted *8* times longer than design. That's the equivalent of driving 400,00 miles on tires rated for 50,000 miles. It's a heck of an accomplishment and I can only applaud the terrific job the design engineers and builders did.

Re:Not so surprising

[Chowderbags]

It might even be the equivaltent of driving 400,000 miles on those tires too!

Re:Not so surprising

[Anonymous Coward]

*8* times longer than 50,000 miles is 450,000 miles. *8* times as long as 50,000 miles is 400,000 miles. ;-)

Re:Not so surprising

[slightlyspacey]

Hey, it's still within an order of magnitude of the right answer and I didn't confuse English with Metric measurments :)

Re:Not so surprising

[Anonymous Coward]

Based on a wheel diameter of 10 inches (per wikipedia) and a revolution count of approx 13 million (per TFA), that's about 6450 miles, give or take.

Re:Not so surprising

[humbads]

Terrific job or white lie? The rover has lasted for 2 years, instead of 90 days. Therefore, someone made a highly inaccurate estimate at NASA. They are not supposed to make such big mistakes. Maybe they failed to realize that martian winds would clean the solar panels of dust, to keep the rover charged through the winter. Maybe NASA purposely set a conservative design lifetime as a PR move. Congress should conduct an investigation. What would happen if NASA made the same error in calculating the travel time for the human Mars mission? Oops. ;)

Re:Not so surprising

[seriesrover]

Well, 90 days was the publicly estimated time - the engineers design for the rover to work for that guranteed time. Anything after that is unpredictable, or not guranteed. What were you expecting - the 90th day everything is working hunky-dory and on the 91st everything falls to pieces?

Re:Not so surprising

[LionOfMacedon]

nothing inaccurate about this,generally they give out estimates which they are *SURE* the rover will perform under almost ANY conditions which might possibly be found in the are they plan to run the rover.this way,assuming the rover does fail after the estimated period,it wont be the engineer's problem.if they do however,give an estimate like an year or so,assuming that the tyres and other things would hold that long,and they don't.someone's gonna get a kick in the butt.

Re:Not so surprising

[mtdnelson]

...and I didn't confuse English with Metric measurments

That's lucky, because one is an adjective describing things from England, and the other is a system for defining measurements. :o)

Re:Not so surprising

[LionOfMacedon]

ok,someone posted approximately the same thing i did,hadnt read that,so sorry for repeating the other poster.

Re:Not so surprising

[Anonymous Coward]

Apparently very few people here remember when they realized the rovers hadn't died 90 days in, as I remember it they thought it would die after 90 days pretty well exactly because of power issues (even with the panels). It was something like they didn't realize the sun would be hotter on Mars because of the weaker atmosphere, so when 90 days came up and they were winging it off the dunes at break neck speeds (kidding) with the last few minutes before it died it came as a surprise when it kept responding, which it kept to the current day.

Also, you give NASA far too much credit for guarentee'ing things when your talking about a group who (I'm not rocket scientist) crashed how many probes before they landed one? Who had one of their shuttles blow up recently because of negligent checking procedures. The thing with NASA is this, they fuck up a lot, when they do half the time whatever they are working on explodes, and the other half it works for 10x + the time they expected it to (like for another example, the space shuttles, which were expected to be decommisioned what? 30 years ago?). I'm guessing for their next adventure they'll blow up 3 x-planes, then the fourth one (much like the swamp castle in Monty Python) will last a hundred years before they'll get grant money to build a replacement again.

Re:Not so surprising

[NickFitz]

... sorry for repeating the other poster

New here?

Re:Not so surprising

[Loonacy]

I have no mod points at the moment, but I'd just like to say: Flaimbait? This was actually a clever joke, and I've no idea why anyone would consider this to be flaimbait. Good show.

Re:Not so surprising

[iamlucky13]

90 days was actually the minimum criteria for the mission to be considered successful. The rover team generally felt pretty confident if the rovers landed successfully and survived infant mortality (which generally occurs because of problems in manufacture or design), then they probably would last pretty well beyond the 90 days. In fact, the original budget provided for operations cost for 90 days for the primary mission, plus a possible 90 day extension, as well as a further 180 day extension in case the rovers were still running at the end of the first 6 months. By that time, even if nothing mechanically had failed, they expected dust on the solar panels to have left them inoperational, as it had to the earlier Sojourner rover after roughly 3 months. Well, they got to one year and the rovers were still showing no major problems, so NASA approved a special additional 1 year extension to their budget rather than simply abandon their $820 million investment when it could still offer scientific return. Now they're over two years, and I'm not sure where the money is coming from, but NASA seems intent on milking them for all they're worth.

Yikes, if calculating trajectories and trip times was as difficult as predicting service life, we'd be in serious trouble.

Re:Not so surprising

[Anonymous Coward]

You need to work on your capitalization, punctuation, spacing, and general sentence structure.

Still a tossup - Rovers dead before Vista released

[SpaceLifeForm]

I still believe both rovers will be alive
when and if Vista is ever released.

Re:Still a tossup - Rovers dead before Vista relea

[therage96]

Aha, but will they still be functioning when Duke Nukem Forever gets released? I mean, 2514AD is a long ways away!

Re:Still a tossup - Rovers dead before Vista relea

[GKThursday]

I don't think their hardware meet Vista's specs.

Re:Still a tossup - Rovers dead before Vista relea

[Anonymous Coward]

Given the hardware most space stuff uses, it probably doesn't even meet Windows 3.1's specs...

At first read, I get dissapointed

[R2.0]

Then I remember a story Spider Robinson told about a cheap digital watch that died on him. He was pretty pissed off, but then he remembered that:

a) it was originall a Crackerjack prize or some other freebie.

b) it was 5 years into it's projected one year battery life.

At this point he gave it a solemn memorial service and kept it in a revered place (I think he may have buried it).

Whenever they finally die, I hope that they find an honored place in whatever museum the future Mars colonists decide to set up.

R2.0

Re:At first read, I get dissapointed

[partymonkey]

Maybe it's just me, but I doubt they spent all that money on the rovers for just 90 days of operation. I'd be willing to bet that they designed them to last 3-5 years. Also, they were probably just setting expectations *really* low, so if the rovers failed early then they still looked good in the public eye.

Re:At first read, I get dissapointed

[ancientt]

Gotta say, I can't figure out whether to be ticked that we can't get accurate projections from the engineers or be proud that we get so much more out of our mission than we require to consider it a success.

I always thought Kirk was hard on Scotty when he asked for whatever was needed in half the estimated time. If engineers design things to last so far beyond their requirements, then maybe it is rational after all.

Maybe though, we need someone running around NASA who knows which engineers are lowballing and will have the nads to tell them to do it in a fraction of the time they say they need.

Re:At first read, I get dissapointed

[timeOday]

Another way to think about it, if you design a switch to last 1000 cycles with 99.99% probability, it will probably last 10 times that long with 99% probability. (I made up the numbers but you get the point.)

This is the same reason I prefer an 80,000 mile powertrain warranty over a 40,000 mile warranty when buying a car - not because any modern car is likely to last under 80,000 miles, but because I figure the one with the longer warranty is more likely to go 150,000+.

Re:At first read, I get dissapointed

[aevan]

Didn't Scotty later admitt (when talking to another engineer) that he always really padded his estimates, that way when he came in ahead of schedule he was a 'miracle worker'?

Re:At first read, I get dissapointed

[HoneyBunchesOfGoats]

Or, car manufacturers could decide that you'll assume "longer warranty == longer-lasting car," raise their warranty to 80,000 miles regardless of the fact that the car is crap, and bank on the fact that you'll want a new car within a couple years anyway.

Re:At first read, I get dissapointed

[Jeff DeMaagd]

A lot of money is spent on probes. I think it would have been unreasonable to expect a 3-5 year life, these things seem to be the longest operating extra terrestrial land rover to have been made. Pathfinder was apparently noted for having an extremely low mission cost for a planetary probe.

I thought it was pretty plausible that they expected them to only last 90 days simply because of the dust problem, that it would cover the solar cells. For a while, it didn't even look like they would last a month due to the software and hardware issues.

Re:At first read, I get dissapointed

[Anonymous Coward]

That was in a TNG episode with La Forge.

Re:At first read, I get dissapointed

[siwelwerd]

Exactly. They probably designed it to have a 95% or so chance of lasting those 90 days, which would require a mean time to failure (of the entire robot) of a much longer time. Not that that makes it any less of an engineering feat.

Re:At first read, I get dissapointed

[eclectro]

These guys will go up and bring the rovers back before Mars colonists get around to building a museum.

Re:At first read, I get dissapointed

[livewire98801]

Scotty: 8 weeks, sir

Kirk: Mr Scott I-

Scotty: But you don't have 8 weeks, so I'll do it for you in 2

Kirk: Mr Scott, have you always multiplied your repair estimates by a factor of four?

Scotty: Of course, Admiral, how else can I keep my reputation as a Miracle Worker?

Kirk: Your reputation is secure, Mr Scott.

If I recall, this dialoge was in ST:3, but I'm not sure of that.

Re:At first read, I get dissapointed

[itsthebin]

I only ever give the 1 2 warranty
once I am gone , too fucking bad.

reality has a place in this world

Re:At first read, I get dissapointed

[edremy]

If you read Squyres' book, you'll see you're sort of correct. Yes, they designed them for more than 90 days- that was the *minimum* they were willing to accept. However, they fully expected both to be dead long before this, victims of dust buildup on the solar panels. They didn't expect the Martians to be cleaning them off so frequently.

Re:At first read, I get dissapointed

[loraksus]

This is the same reason I prefer an 80,000 mile powertrain warranty over a 40,000 mile warranty when buying a car - not because any modern car is likely to last under 80,000 miles

I worked for GM as CAC manager for a couple months, trust me, that assumption is not one that you want to make.
For other car companies, it may be advertising, for GM, it is something to strive for.

Re:At first read, I get dissapointed

[dynamo52]

Maybe it's just me, but I doubt they spent all that money on the rovers for just 90 days of operation. I'd be willing to bet that they designed them to last 3-5 years. Also, they were probably just setting expectations *really* low, so if the rovers failed early then they still looked good in the public eye.

I read an interview with one of the scientists somewhere where he admitted to taking a page out of Scotty's (i.e. Star Trek) playbook. Scotty was training a junior engineer and told him something to this effect. "When the captain asks you how long it will take to fix a problem, if you determine hat it will take one hour, tell him three. When you finish it in a liesurly two hours you come out a hero"

Re:At first read, I get dissapointed

[dynamo52]

Here is the link
http://www.smthop.com/articles1details.asp?newsnum =374

Re:At first read, I get dissapointed

[Dominic_Mazzoni]

That's partially true, but another important aspect of it is that if they had planned on a five-year mission up-front, the budget would have been several times larger - and in fact the project might never have been funded at all. So they decided on a mission length long enough to get some interesting science done, but short enough to look cheap.

After 90 days, they went and asked for additional money. What's NASA going to do, stop running the rovers because they're over budget? Of course not. Unfortunately now they're eating into money that would have gone to other Mars missions. But it's still far more sensible to spend a dollar on the rovers already on Mars than on a future rover that may or may not make it to Mars.

Re:At first read, I get dissapointed

[AnotherBrian]

Specify Relics

Re:At first read, I get dissapointed

[ForestGrump]

And...with a warranty set at say 40k, your chance of failure is very small. As you extend the warranty out, the chance of failure increases, but so does the reasons to void the warranty.

For example, the transmision dies at 70k. You take it into the stealer for them to fix it. Well sir, you should have had the trans flushed every 30k. Because you failed to do so, at 30k and 60k, you have no warranty. (hypothetical of course)

Yippie for a longer warranty? No, it's statistics majors, accountants and marketing dept pumping you for all you're worth.

Grump.

Re:At first read, I get dissapointed

[Khyber]

I beg to differ. In anything involving space exploration, I'd be the type to over-engineer something just to make damned sure I got the wanted usage out of it, and any extra usage afterwards is just a bonus. NASA may not be very well-funded right now, but we've got engineers that know all too well how harsh space really is. They did the best they could and obtained results far better than they had expected.

Re:At first read, I get dissapointed

[Scarblac]

I think they were designed so that they were _absolutely certain_ they'd work for 90 days. Which means that, with some luck, they're likely to last a lot longer.

Re:At first read, I get dissapointed

[Baloo Ursidae]

That is, if the sun doesn't scorch them into nothing first. Take, for example, the effects the sun have on similar objects in an environment similarly ill-suited for intelligent life: Southern California. Plastic and rubber has 9 months to a year before the sun rots it out, thin metal surfaces (aluminum in particular) fade and get worn through quickly, even factory-tinted windows bleach clear over time.

Though now that I think of it, if someone built tract housing out of cardboard (1/16th acre lots with no yard, driveway, nearby mainline transit or on-street parking) and charged at least $480,000 a unit for it and called it New San Jose, the Californians would flock to that. We should strive to make that a reality...

It's not "dragging" the sixth wheel

[parc]

It's more accurate to say that the wheel is free-spinning. It isn't contributing to drive power, but it's not drawing any current, either. It can still steer, so it's not off at some odd angle.

Additionally, there's only been a couple days worth of data -- noone really knows why the motor stalled.

Re:It's not "dragging" the sixth wheel

[cmacb]

Doesn't really LOOK like it's free spinning:

http://marsrovers.jpl.nasa.gov/gallery/all/2/f/781 /2F195698779EFFAQ15P1210L0M1.JPG

Re:It's not "dragging" the sixth wheel

[BigFoot48]

"Quick, hit the brakes and switch to the rear camera! Those damn Martians are walking by the front of the rover again!"

Re:It's not "dragging" the sixth wheel

[Prof.Phreak]

Depends on the motor type; it may just lock when no power is applied to it.

Re:It's not "dragging" the sixth wheel

[Firehed]

Doesn't look like there's a trail to indicate the other wheels are spinning correctly, either. I'd wager that neither one of us knows enough about martian spacecraft design to say for sure. Having said that, the long gouging of dirt inclines me to agree with you.

Re:It's not "dragging" the sixth wheel

[Saeed al-Sahaf]

http://origin.mars5.jpl.nasa.gov/gallery/all/2/f/7 82/2F195787507EFFAQ67P1209L0M1.JPG Yes, it looks like it's locked up. (have a look at the pic)

Re:It's not "dragging" the sixth wheel

[Anonymous Coward]

Wait wait wait, do you mean to say it's not free spinning?

Re:It's not "dragging" the sixth wheel

[Tablizer]

They stopped using the wheel about a year ago for a while because it was having problems as if the lubricant was wearing off, and it indeed did *not* free-spin when power was not sent to it. They simply dragged it around by running the rover backward. They found it easier to control the rover by dragging the bum wheel rather than by pushing it. They only used the wheel for close-up control when rocks were being targeted. Eventually it started working properly for a while, and now won't turn at all. It does not appear they have a "free spin" mode. Dragging is it.

I beleive they have a video about the last time the wheel was left dragging. They did some test-bed simulations of an Earthly rover copy. Page down to the "Driving Uphill Backwards" portion, about half-way down the page:

http://marsrovers.jpl.nasa.gov/gallery/video/spiri t01.html

Re:It's not "dragging" the sixth wheel

[Tablizer]

Looks like it's locked up. (have a look at the pic)

It appears the dragging uncovered some whitish rock. They've discovered high-salt soil in a similar way before--when the rover turns it sometimes digs a mini-trench as it pivots. After one such pivot they noticed some whitish soil was uncovered, so they made the rover "sniff" at it and found it to be the saltiest soil yet found on Mars.

Perhaps they can spin it (pun) this way:

NASA PR Rep: "The wheel is not broken, the dragging you see is....um....is merely a technique to study lower depths of high quantities of soil."

NASA simply needs to hire more corporate bullshitters :-)

Re:It's not "dragging" the sixth wheel

[Anonymous Coward]

yeah this is a year old, what the hell, you suck slashdot

Re:It's not "dragging" the sixth wheel

[Tablizer]

yeah this is a year old, what the hell, you suck slashdot

Hold on, Tex. The older problem was that it drew too much current. It still worked and they used it for occasional tight maneuvering. Now it appears to be all-the-way gone. However, it went back to normal for a while before it completely failed. It is even possible the problems are not related.

The speculation was that lubricant was not spreading around enough, creating friction, and that the problem went away because lubricant finally dripped into the right place. A sudden failure does not really match that hypothesis as one would expect the friction (power current needed) to slowly drift upward again before the failure. At this point nobody really knows what happened.

Either way, the first problem was less severe and thought to have since gone away.

Re:It's not "dragging" the sixth wheel

[sec]

I'm not aware of any type of motor that simply locks up when no power is applied. However, there are multiple scenarios which could cause the wheel to lock, or at least to become so difficult to turn that it drags rather than freewheels.

1. Bearing failure. Considering the atmosphere on Mars, cold and dusty, this is a distinct possibility. However, if this were the case, the motor should be drawing a lot of current, and the motor is reported to be drawing none. Perhaps there's a failsafe circuit that shuts the motor off if it draws excess current, though.

2. Gears. If the motor is geared down by a significant amount before driving the wheel, it would require more force to turn the wheel manually. If there was a worm gear in the drive train, it would not be possible to turn the wheel manually, since worm gears only work one way.

3. Short circuit. If you short-circuit the terminals of most motors, they become more difficult to turn by hand. The reason for this is that in this situation, the motor is effectively a generator attempting to provide power into a short circuit. A short circuit can sink a lot of energy, and generators are more difficult to turn the more energy they are asked to supply. Again this would mean that the motor should be drawing a great deal of current, but there may be a failsafe circuit which shuts it off.

4. Internal Jam. Certain types of permanent magnet motors have the armature surrounded by a relatively brittle permanent magnet stator. Mechanical shocks to the motor can cause pieces of the stator to break off and become wedged between the stator and the rotor, causing the motor to jam. This is most common in cheap motors that are used in toys and cassette recorders. I should hope that the rovers use something of higher quality!

Re:It's not "dragging" the sixth wheel

[StarkRG]

I'm not aware of any type of motor that simply locks up when no power is applied.

Probably havn't been around many types of motors then. It could also be the gear configuration (wormdrive would make it impossible to free spin), or perhaps it's not locked up but the gear ratio is such that there's not enough traction to turn the motor (in which case it's probably better that it drags)

What they need is some way to pop the wheel off, perhaps with another in reserve (if only a freespinning one), kinda like PeeWee's handlebar...

Re:It's not "dragging" the sixth wheel

[petermgreen]

i'm not aware of any type of motor that simply locks up when no power is applied.
the most obvious is one with a worm gear drive (often seen inside low rpm gearmotors)

Re:It's not "dragging" the sixth wheel

[AaronLawrence]

That wouldn't be the *motor* that's locking up then, would it?

Re:It's not "dragging" the sixth wheel

[loconet]

Because you are posting from Mars and you can see it out your window right? ;)

Re:It's not "dragging" the sixth wheel

[Anonymous Coward]

...Additionally, there's only been a couple days worth of data -- noone really knows why the motor stalled....

Probably a Swiss thing (since the motor was made in Switzerland). After the last martian winter, the motor waits for a switch to snow mobile modus...

Cheers

The coward

Re:It's not "dragging" the sixth wheel

[Eternauta3k]

Stepper motors
Pneumatic motors

Only lost 1 wheel? pfft

[Anonymous Coward]

If a dog can walk on two legs you better hope this thing keeps going, otherwise it's pretty embarassing.

http://youtube.com/watch?v=OZqVvYkCe68

Re:Only lost 1 wheel? pfft

[Anonymous Coward]

Embarassing??? Did you read the part about being 2 years into a 90-day mission?

Re:Only lost 1 wheel? pfft

[wik]

... but engineers are still trying to get four legs to not look like a hysterical, deranged beast.

Re:Only lost 1 wheel? pfft

[Anonymous Coward]

Dog with two legs? You must have seen it on an indian reservation.

Re:Only lost 1 wheel? pfft

[archen]

Actually I used to have a dog with two legs. I named him cigarette. Ever day I'd take him out for a drag.

heh, sorry.. had to make the joke...

Re:Only lost 1 wheel? pfft

[Rob Carr]

Our vet got a call for a dog involved in an accident. When the vet got there, she found a dog that had lost most of the front right and rear left legs to a crush injury. The dog was running around and was hard to catch. They expected the vet to put the dog down, but she wound up cleaning up the amputations and infections. The dog was given to a family. Last I heard, dog and family were doing fine, although if the dog gets out of the house without a leash, it is still hard to catch.

C'mon ya pansy

[Anonymous Coward]

The NASA engineers always triumph!

Re:C'mon ya pansy

[Krakhan]

*Rushes in* No one expects the Spanish Inquisition!

Re:C'mon ya pansy

[Anonymous Coward]

Even less expected is the French Inquisition! *french laugh*

Re:C'mon ya pansy

[Anonymous Coward]

Come back and fight like a man! You red bastard!

Re:C'mon ya pansy

[tengwar]

What - is the maximum speed of a Martian rover?

Re:C'mon ya pansy

[bluephone]

"Spirit, or Opportunity?"

"I don't knoooooooooooo---"

Re:C'mon ya pansy

[kimvette]

You're a loony!

Re:C'mon ya pansy

[tengwar]

It's just one of those things you have to know as a NASA administrator.

exploration will continue

[MoFoYa]

I think its great that the mars rovers lasted as long as they have. when you consider the failed mars mission attempts, spirit and opportunity are huge successes that have long outlasted their expected lifespan. The new mars orbiter "MRO" is sure to provide more information about the surface of mars, and possible landing sites for even more capable landers in the future. my question to /.ers is this: should we be focusing so much on mars or should we be looking toward other possible outposts/life harboring worlds like europa. and the new horizons mission to pluto - a waste of time, or an exciting new learning opportunity? personally, i doubt life will be found on mars. and i'm doubtfull any significant life will be found anywhere in our solar system. but, we are natural explorers who will continue to explore, even with a bum wheel.

Re:exploration will continue

[Telvin_3d]

I think that we should explore anywhere and everywhere. We still know so little about anywhere in out solar system that any single mission is going to bring huge returns, regardless of where it goes. Frankly, if there was real investment in knowledge going on (or any real long term interest in science and research), there should be at least one mission heading to every piece of rock in the solar system large enough to be considered a moon. Part of that is that we would find out all sorts interesting things about them, and get sent back millions of desktop worthy pictures, but mostly because the biggest jumps in our technology have always come when we were trying to achieve things beyond what we had any right to expect. Many business and government leaders like to continentally forget that their products are built on the side benefits of major projects that came from areas like cold war weapons research or the space race (arguably two sides of the same coin, but that is something else), and there lies the real benefit of these missions.

Yeah, Spirit and Opportunity have let us learned a lot about Mars, but how much have we learned about remote robotics, operating machines under extreme conditions, and low maintenance designs? Personally, I think the later are the best reasons to be on Mars.

Yeah, Spirit and Oprotunity have let us learned a lot about Mars, but how much have we learned about romote robotics, operating machines under extreme conditions, and low matiance designs? Personaly, I think the later are the best reason to be on Mars.

Re:exploration will continue

[Anonymous Coward]

Yea, because slashdotters are really fucking knowledgable.

Re:exploration will continue

[cashman73]

my question to /.ers is this: should we be focusing so much on mars or should we be looking toward other possible outposts/life harboring worlds like europa.

Didn't HAL (or Dave Bowman, or whomever the aliens were) tell us, "ALL THESE WORLDS ARE YOURS EXCEPT EUROPA. ATTEMPT NO LANDINGS THERE."?

Re:exploration will continue

[Tablizer]

should we be focusing so much on mars or should we be looking toward other possible outposts/life harboring worlds like europa.

A Europa orbiter mission was recently cancelled by the Bush administration. There is still a focus on Mars because of Bush's plan to land humans there in 30 years or so. For one, we need to know if there is life on Mars so as not to contaminate either or both planets. If life is found on Mars, perhaps a manned mission should be skipped until more details come about the nature of it. Otherwise, astronauts may pass to us the Wooping Cough From Hell.

Further, a Europa mission would probably have to penetrate a few miles into the surface to get to the alleged ocean there. That is more complicated and expensive than probing the surface of Mars. Mars is still the cheapest known place to look for astrobiology.

But I agree that a Europa orbiter would be a nice idea as a prelude to future life-detection missions. Too bad it was cancelled. Maybe Prez Hillery will reinstate it :-)

Re:exploration will continue

[aussie_a]

For one, we need to know if there is life on Mars so as not to contaminate either or both planets.

Too late buddy. Most current scientific theories on such things say that nature has more then had plenty of opportunity (and the means) to send life one way, or even both ways. So it's quite possible one of our planets (if not both) were contiminated by the other.

Re:exploration will continue

[Tablizer]

So it's quite possible one of our planets (if not both) were contiminated by the other.

True, but that is only a theory. We won't really know until we study Mars life in detail. Even if there is only a 1 in 1000 chance of a human-ending bug on coming back from Mars, that is still too high for comfort.

Re:exploration will continue

[aussie_a]

We won't really know until we study Mars life in detail

Which many say won't be possible until we get to Mars.

Even if there is only a 1 in 1000 chance of a human-ending bug on coming back from Mars, that is still too high for comfort.

The existence of there being life at all on Mars is only theoretical, so much so that you won't get a statistic of any sort (well, of any reliability, I'm sure plenty of scientists have made claims, but I doubt they agree with each other within any realistic range), let alone the existence of a bug that can be transmitted to humans, let alone the existence of a bug that has the ability to wipe out mankind. The fact that there has to be two other criterias (both of which the possibility are currently unknown) before we can even get to a bug that will wipe out mankind, I'd say the possibility is fairly small. Much smaller then your 1 in 1000

Re:exploration will continue

[gstoddart]

my question to /.ers is this: should we be focusing so much on mars or should we be looking toward other possible outposts/life harboring worlds like europa. and the new horizons mission to pluto - a waste of time, or an exciting new learning opportunity?

I wouldn't want to see Mars pursued to the exclusion of other destinations.

But given that Mars is nearer, and we still have a pretty spotty record with actually getting things to Mars, it's probably still quite useful as a proving ground for technologies. The more data and success you get in going to Mars, the more you learn for other applications. Heck, an unmanned return trip would be amazing to see.

How much longer and more complex is sending something to Pluto? Probably moreso, and it'd probably take several years in transit.

It's not like we can just say OK, Mars is a lifeless rock so there is no more value in going there. There's plenty more to learn about spaceflight and Mars itsself.

I really like the new generations of probes which have been showing themselves over the last bunch of years. They're doing some really cool science from my perspective.

Re:exploration will continue

[m13.higgs]

"the new horizons mission to Pluto - a waste of time" Why do think New Horizons is a waste of time? Sure, we're not expecting to find life there, but the Kuiper belt is one of the most mysterious regions in our solar system. Just think of all the bodies we're beginning to find there that are bigger than Pluto! And we know next to nothing about any of them! There are so many unanswered questions about the Kuiper belt and Pluto that I think that it's anything but a waste of time to go there.

Re:exploration will continue

[Tablizer]

[We won't really know until we study Mars life in detail] Which many say won't be possible until we get to Mars.

The cheapest way to find out is to return samples via remote probes and analyze them back on Earth where the labs can be the best. However, that does not really solve the contamination risk. I think a moon-based lab may be the way to go. If the moon base is infected, then it won't spread to Earth.

As far as your prabability comments, the bottom line is that we don't know. Even if humans are not affected, we could screw up say Earth bacteria and change the chemistry of Earth. Look how foreign speices has affected continents. I agree the risk is small, but not zero.

Re:exploration will continue

[psergiu]

We still have 4 years 'till then.

Re:exploration will continue

[MoFoYa]

'...the new horizons mission to pluto - a waste of time, or an exciting new learning opportunity?'

read the whole sentance. it was a question with two possible answers that were both part of the sentance.

Cold

[MichaelSmith]

Its almost winter in the southern hemisphere of Mars. I wonder if there is a chance that a contact has contracted in the cold enough to break off power to this motor. Who knows? Spirit has been lucky before. Perhaps this wheel will start working again in the summer.

Failing that I am available to fix the broken motor, assuming that NASA can provide transportation :)

Re:Cold

[HermanAB]

Sure, they can provide transport - one way - and there is that little niggling problem with orbit insertion and parachute deployment that sometimes crop up... :)

Re:Cold

[Prof.Phreak]

Sure, they can provide transport - one way - and there is that little niggling problem with orbit insertion and parachute deployment that sometimes crop up... :)

In other words, they'll use a large trebuchet to get you there (or somewhere... either way, it will be fun!)

Re:Cold

[modecx]

I'd say that it's more likely that my public utilities company has shut down that motor for not paying money for energy. They're that just evil.

Re:Cold

[Anonymous Coward]

No problem. I'll drive.

Re:Cold

[Tablizer]

Failing that I am available to fix the broken motor, assuming that NASA can provide transportation :)

After you land: "Micheal, this is Houston. Due to the budget and trade deficit, we have no budget left for your return trip. However, we are sending you a Walmart keychain, made in China, as a token of our appreciation."

Re:Cold

[Petrushka]

--
Magnus frater spectate!

I don't think that sig means what you think it means. To illustrate: what it actually means is, "Big brother -- hey, you lot, take a look!" If you want it to mean what I think you want it to mean, try "magnus frater te spectat."

Re:Cold

[ozmanjusri]

try "magnus frater te spectat."

Don't you mean "Magnus frater spectat te"?

Re:Cold

[Fulcrum of Evil]

Linky!

Centurion: What's this, then? "ROMANES EUNT DOMUS"? "People called Romanes they go the house"?
Brian: It, it says "Romans go home".
Centurion: No it doesn't. What's Latin for "Roman"?
Brian: (hesitates)
Centurion: Come on, come on!
Brian: (uncertain) "ROMANUS".
Centurion: Goes like?
Brian: "-ANNUS"?
Centurion: Vocative plural of "-ANNUS" is?
Brian: "-ANI".
Centurion: (takes paintbrush from Brian and paints over) "RO-MA-NI".
"EUNT"? What is "EUNT"?
Brian: "Go".
Centurion: Conjugate the verb "to go"!
Brian: "IRE". "EO", "IS", "IT", "IMUS", "ITIS", "EUNT".
Centurion: So "EUNT" is ...?
Brian: Third person plural present indicative, "they go".
Centurion: But "Romans, go home!" is an order, so you must use the ...?
(lifts Brian by his hairs)
Brian: The ... imperative.
Centurion: Which is?
Brian: Ahm, oh, oh, "I", "I"!
Centurion: How many romans? (pulls harder)
Brian: Plural, plural! "ITE".
Centurion: (strikes over "EUNT" and paints "ITE" to the wall)
(satisfied) "I-TE".
"DOMUS"? Nominative? "Go home", this is motion towards, isn't it, boy?
Brian: (very anxious) Dative?
Centurion: (draws his sword and holds it to Brian's throat)
Brian: Ahh! No, ablative, ablative, sir. No, the, accusative, accusative,
ah, DOMUM, sir.
Centurion: Except that "DOMUS" takes the ...?
Brian: ... the locative, sir!
Centurion: Which is?
Brian: "DOMUM".
Centurion: (satisfied) "DOMUM" (strikes out "DOMUS" and writes "DOMUM") "-MUM".
Understand?
Brian: Yes sir.
Centurion: Now write it down a hundred times.
Brian: Yes sir, thank you sir, hail Caesar, sir.
Centurion: (salutes) Hail Caesar.
If it's not done by sunrise, I'll cut your balls off.
Brian: (very relieved) Oh thank you sir, thank you sir, hail Caesar and everything, sir!
The scene cuts to a very tired Brian finishing off one last iteration of ROMANI ITE DOMUM. The camera zooms out to show the castle covered entirely in ROMANI ITE DOMUM
Brian: Finished!
Roman Soldier: Right. Now don't do it again. (Wanders off)

Re:Cold

[Petrushka]

There's no difference.

Re:Cold

[HermanAB]

Yeah, you are correct correct! ;)

Conversation I never Overheard

[Black Copter Control]

Martian1: It broke it's leg. I say we shoot it and put it out of it's misery.
Martian2: nah. It seems to have such a drive for life.

Re:Conversation I never Overheard

[Anonymous Coward]

Martian3: How come neither of you knows how to use apostrophes correctly?

/shoots martians 1 and 2

Re:Conversation I never Overheard

[bckrispi]

Oh, you make me verrry angry. Verrry angry indeeeeed!!

Re:Conversation I never Overheard

[Marce1]

Martian4: Proper Noun Police; Put the gun down and step away from the sentence!

/Edges toward Martian3 with a capital M held out, still aiming

Re:Conversation I never Overheard

[Anonymous Coward]

That's fucking rich. You correcting people's spelling.

Re:Conversation I never Overheard

[Enviro]

Martian 5: I hear bananas are quite yellow these days.

Late breaking news?

[Theatetus]

TripMaster Monkey, where are you?...

Re:Late breaking news?

[Anonymous Coward]

Getting a life finally? I suggest you do the same.

Re:Late breaking news?

[Anonymous Coward]

Posting anonymous trolls does not count as a life, TMM.

Re:Late breaking news?

[KORfan]

The Martians have obviously caught up with him.

2 years into a 90 day mission...

[HermanAB]

Hmmm, typical NASA project, 21 months late and far over budget. :)

Late Breaking News:

[iced_773]

A sense of triumph swept our fair red world today when reports came in that the Grand Army of the Council had damaged one of the robotic invaders from the evil blue planet. K'Breel, speaker for the Council of Elders, made the following comment:

This was a great victory in our war with the evil blue planet. While we have only impaired the horrid machine's movement, we will continue to strike until it and its dreadful twin are pools of molten metal.

When a journalist suggested that the terrible monstrosity had merely worn out one of its locomotive rotators, K'Breel had the traitor's gelsac mutilated immediately.

Apologies to TripMaster Monkey.

Re:Late Breaking News:

[Anonymous Coward]

And now the Council of Elders may become yet another illustrious Slashdot cliche, following in the footsteps of "That's not a space station..." and "Oh, wait, no, it's actually not big enough to hold all my pr0n." Congrats to TMM.

Re:Late Breaking News:

[iced_773]

The rest of us, huh? Including this guy? I think you're the same troll who stalks TMM. And don't try to pass off any of that "I know for a fact there are many of us" bull. Those of us decent enough to log in to speak our minds aren't falling for it.

Also, if it isn't funny, then why am I modded that way? I was also modded Underrated, as you can see in the moderation breakdown. If the civilized people who log in and post meaningful things to Slashdot enough to get mod points think it's funny, then that is all that matters. I don't care what a faceless AC troll thinks, and neither does anyone else. That's why you were modded Overrated.

Re:Late Breaking News:

[Anonymous Coward]

Your sig has too many lines.
Please remove three.
I am not a crackpot.

Remarkable

[ctetc007]

It's remarkable how much longer these guys have still been alive even after they already completed their originally planned goals. Here's one thing that NASA did right.

Shoulda got the AAA Extended Service Plan

[slickwillie]

100 mile free towing too!

Re:Shoulda got the AAA Extended Service Plan

[Silver Gryphon]

No, they use OnStar but Spirit hit the NOS button by mistake. The little guy was last seen hurtling across the planet surface at 2 meters per hour.

Failed brushes?

[dougmc]

"It is not drawing any current at all," said JPL's Jacob Matijevic, rover engineering team chief. One possibility engineers are considering is that the motor's brushes, contacts that deliver power to the rotating part of the motor, have lost contact.

Brushless motors are generally 1) more efficient and 2) longer lasting (with no brushes to wear out) and 3) more expensive (especially when you include the ESC, electronic speed control) than otherwise similar brushed motors. (But when you send something into space, who cares about an extra $1000 on motors?) I'm rather surprised that they didn't go brushless in something like this. Brushless motors are also cleaner, as there's no brushes to wear down over time. This is critical in zero gravity environments like orbit (nobody wants brush-dust floating around) and wouldn't be so important on Mars, but even so ... I wonder why they used brushed motors. Even if they things weren't supposed to last very long, you'd think brushless motors would be more efficient, giving them some extra power to work with, for not much extra money.

(My experience with brushed and brushless motors comes from R/C planes, where a brushless motor is sometimes twice as powerful and 50% more efficient than a similarly sized brushed motor. Of course, a large part of this is that the brushed motor is dirt cheap, made cheaply in every way, and the brushless motors are of higher quality, but even so, even when comparing high quality stuff (and not cheap speed 400 can motors) the brushless are signifigantly better.)

Re:Failed brushes?

[HoneyBunchesOfGoats]

I have a hunch that the brushed motors NASA used in the rovers are probably a little bit more expensive and higher-quality than what you're used to dealing with on miniature airplanes. There are most likely some design issues we don't know about that made them use a brushed motor.

Re:Failed brushes?

[iggymanz]

The rover uses maxon's motors, which also are used in artificial hearts, surgical tools, and underwater robots. those aren't your mother's DC motors 8D

Re:Failed brushes?

[Anonymous Coward]

Actually, having recently heard a talk with people from JPL I can tell you why. They went with brushed motors because it was what had been previously used and was, therefore, seen as a safe option. For future robotic missions they plan on using brushless motors.

Re:Failed brushes?

[v1]

Brushless motors are more complex, and require an array of active electronics inside them to produce the AC and modulating magnetic field they need to operate. Most brushless motors are lower torque than their brushed counterparts. (majority, I know there will be exceptions) Brushed motors are more mechanical in nature and suffer from the usual mechanical issues, but they are less prone to failure than brushless. Also, traveling through space and landing on a planet that may not have a protective magnetic field, active (transistor based) electronics must be carefully protected against emi that can disable or damage them.

I'm sure they went brushed for a variety of very good reasons. The technology of brushless was available when the rovers were designed, and I can't imagine NASA not seriously considering them.

Re:Failed brushes?

[griffjon]

IN fact, most likely they went with brushed for exactly reasons you mention: ...require an array of active electronics

Hm -- what things don't work great without a lot of shielding in space?

I'm not saying it couldn't be done, I'm saying it might've been the right choice given size and electronics-reliability constraints.

Also, as a rebuttal to the "90 days was an intentional understatement", I'd put forward that it was probably an understatement, and that the 2-year mark is probably beyond design spec. What we're seeing here is a project where everything's gone Very Well. We all know that those are rare gems, so give NASA some share of the glory.

(...they at least got their measurement units right this time....)

Re:Failed brushes?

[FinalMidnight]

A friend of mine is part owner of a cutting edge motor design company. He had a hand in the design of the Fuji Xerox Desert Rose, an award winning Solar Car. He said that looking inspections of the designs they used for the rovers showed them laughable in many regards. Little though was given to efficiency. None of the design team expected the solar systems to work well or last long. The Rovers both carry a massive weight of non-rechargeable batteries (alkaline cells, or something) and very little of rechargeable cells. Unable to even discard the spent battery cells. The rovers have been carrying the spent cells ever since they ran flat, doing horrible things to the power to weight ratio and other such bad stuff.

Also, an efficient asynchronous electric motor design would have been about 30% the weight (or 70% more power, pick one) and running at greater than 90% efficiency. And I'm not talking untested prototypes, either. Motors of this design and build have been run in Solar Car races for the best part of a decade.

While NASA is very proud to have exceeded expectations with the Rovers, I think this is mostly because their expectations of solar powered vehicles were so abominably low. Perhaps they will take things more seriously from now on.

Re:Failed brushes?

[fbg111]

Also, as a rebuttal to the "90 days was an intentional understatement", I'd put forward that it was probably an understatement, and that the 2-year mark is probably beyond design spec. What we're seeing here is a project where everything's gone Very Well. We all know that those are rare gems, so give NASA some share of the glory.

You're right, I attended a presentation by Steven Squyres, Mars Rover PI. During the QA I asked exactly this question and he pretty much said the same thing. Their goal was 90 days, but they overengineered the rovers to counter the uncertainty such a complex mission would entail. They wanted to guarantee 90 days, which they did. They also got really lucky - just as Rover was about to go offline due to dust buildup on its solar array, it crested the ridge of a crater and a gust of wind blew all the dust off, significantly extending its longetivity. Given Mar's thin atmosphere, they got really lucky to be in the right place at the right time for such an event.

Re:Failed brushes?

[Tablizer]

While NASA is very proud to have exceeded expectations with the Rovers, I think this is mostly because their expectations of solar powered vehicles were so abominably low. Perhaps they will take things more seriously from now on.

Their budget was for 90 working days. That is how the contracts stipulated payment. Further, the solar panels have been cleaned repeatedly by dust devils. Experience with the 2 Viking landers showed that dust builds up pretty quickly on probes and they understandably factored this into the design. The dust devil cleansing was a lucky accident. They had no certain landing areas picked out when the rovers were being designed, so they could not expect to rely on landing in whirl-windy areas, even if such could be identified from orbit. (It appears there are more dust devils near the equator than where the Vikings landed. However, there are probably also regional variations, based on the "criss-cross" patterns seen from orbit and created by dust devils.)

In fact, it has been a while since Spirit has been cleaned by one, and that is one reason they have to rush to sun-facing slope. Future crafts that land in non-whirl-wind areas of Mars may face an early demise if they rely on solar (unless they bring their own cleaning systems).

I believe Spirit had about 2 whirl-wind "cleaning sessions". Next year when the winds pick up it may have 4 or zero. It is the luck of the cards that determine it, and so far only during the summer. Thus, Spirit may have a sluggish spring.

In short, I see no reason to bash Nasa's general approach. Sure, it would be nice to have a fat budget to include bells and whistles for extended missions, but the budget is the budget. Plus, they had a fairly short ramp-up time between approval and build. They had to use a lot of existing Sojourner technology almost as-is to reach the deadline.

Re:Failed brushes?

[Rakishi]

None of the design team expected the solar systems to work well or last long.

Dust buildup was supposed to render them useless after a while; luckily it seems some wind solved that problem for them.

The Rovers both carry a massive weight of non-rechargeable batteries (alkaline cells, or something) and very little of rechargeable cells. Unable to even discard the spent battery cells. The rovers have been carrying the spent cells ever since they ran flat, doing horrible things to the power to weight ratio and other such bad stuff.

Asfaik both rovers use Lithium-Ion batteries, well specially designed ones. Older rovers used non-rechargeable batteries, most likely to avoid potential failures.

Also, an efficient asynchronous electric motor design would have been about 30% the weight (or 70% more power, pick one) and running at greater than 90% efficiency. And I'm not talking untested prototypes, either. Motors of this design and build have been run in Solar Car races for the best part of a decade.

There is a difference between running something on earth with a checkup right before it's use, and sending something into space for over a year and having it then run (With no tune up) on an alien world. For example on Earth the radiation isn't high enough to fry normal electronic circuits. Not to mention that your nice solar car doesn't get to deal with temperatures that make Antarctica look pleasant.

Same thing with your rechargeable batteries, they may work great when they're brand new and in an ideal environment but given a few years and they may be worthless.

Efficiency was not on their mind because having it work was more important.

Re:Failed brushes?

[Anonymous Coward]

I very much doubt they are using brushed motors in this application. Brushless DC motors would be much more robust and efficient.

Re:Failed brushes?

[dougmc]

The rover uses maxon's motors which also are used in artificial hearts, surgical tools, and underwater robots

Maxon makes lots of motors, both brushed and brushless. If you look at their web site, you'll notice that most of their new motors are brushless.

As for the list of applications you gave, I'm guessing that new designs of these products use mostly brushless motors now, if only for the reason that they last longer and the brushes aren't ground down to dust over time.

those aren't your mother's DC motors 8D

My mother doesn't need a Rascal yet. In any event, I doubt these motors are that different from what use use down here on Earth. Sure, they're probably built better, with better materials and such, but the general design and layout is probably very similar.

Re:Failed brushes?

[dougmc]

Brushless motors are more complex

Actually, they're simpler, since there's no brushes. Generally the permanent magnets are on the shaft that rotates, and the electromagnets are on the part that doesn't, with three wires coming out (and possibly five more for a sensored model, but the sensorless models are more popular now.) Ignoring the older sensored models, the brushless motors are signifigantly simpler than brushed motors.

and require an array of active electronics inside them to produce the AC and modulating magnetic field they need to operate.

Actually, the electronics are generally outside the motor, in an ESC (electronic speed control), but I'll admit that it doesn't matter where they are. Brushed motors use an ESC as well to control the speed, so you've got some electronic parts either way. You're right that a brushless ESC is more complex than a brushed ESC, but the difference isn't really that signifigant.

Most brushless motors are lower torque than their brushed counterparts. (majority, I know there will be exceptions)

Torque is a function of motor design. It really has little to do with brushed or brushless, and you can certainly make high torque brushless motors if desired. If you need a motor with more torque but the same power (and less speed, since power = torque * speed) you either design an appropriate motor, or adjust your gear ratio so the amount of torque your motor does provide is appropriate for your use.

Brushed motors are more mechanical in nature and suffer from the usual mechanical issues, but they are less prone to failure than brushless.

And I disagree completely. Brushes wear out. (So do bearings and bushings, so it's a race to see which one wears out first, but in my experience, it's usually the brushes.) And for anything where you control the speed of the motor, you'll have an ESC (electronic bits) that can fail, but as a general rule of thumb, electronic bits are more reliable than mechanical bits.

Also, traveling through space and landing on a planet that may not have a protective magnetic field, active (transistor based) electronics must be carefully protected against emi that can disable or damage them.

Even the brushed motors will have ESCs on devices like the Mars Rovers (since the alternatives suck for a robot) and so either way you'll have active electronics to deal with. Also, the Mars rovers aren't operating in space -- the atmosphere (thin as it is) and magnetic field of Mars do provide considerable protection (compared to a satellite or something that is in space) against things like ionizing radiation.

This stuff isn't rocket science. Even things like scooters, Segways and electric cars use similar technology.

The technology of brushless was available when the rovers were designed, and I can't imagine NASA not seriously considering them.

I'm guessing that the AC who posted in this thread was right on -- that NASA used brushed motors because they've used them in the past and they worked fine then, so they'll work fine now -- when you're spending billions of dollars on things that can't be repaired in the field, you tend to stick with what's tried and true rather than what's 15% more efficient but not quite so well tested. I suspect that future rovers will have brushless motors, however.

Re:Failed brushes?

[Fulcrum of Evil]

as a general rule of thumb, electronic bits are more reliable than mechanical bits.

Does your general rule include high radiation environments? Mars has an atmosphere, but not much of one.

Re:Failed brushes?

[FinalMidnight]

An Asynchronus AC motor has exactly one moving part. That would be (ta da!) the bearing.

Too complicated to work well under the conditions, eh?

An Australian adventurer wanted to drive an electrical vehicle to the south pole, not that long ago. The Solar Car motors were one of the only two considered, because of the large body of field test data and telemitry that exists for the motor design.

Admittedly, you have the complications of the electronic controller, but this would be solved in exactly the same way as other electronic issues presented to the design team.

Of the LI batteries in the Rovers, _most_ of them are non rechargeable. I understand the eggs and baskets arguments, but I point out that NASA has gone from being a technology Visionary circa 1965 to one of the most technologically conservative organisations circa 2000.

Or are you going to tell me we should have sent Mr Armstrong to make that one small step with "Proven Technology"?

NASA is cutting budgets and doesn't have the money for testing. Fair enough. But innovation is cheap.

Re:Failed brushes?

[Mike1024]

Well, different designs of motor have different performance characteristics.

For example, the starting torque of an asynchronous motor is actually well below the maximum torque, since at that point slip is infinite. Also, one would need a precise, low-speed control option for a mars rover; the speed of an induction motor depends on (among other things) the frequency of signal driving it. But the current in the rotor is created by induction, and at low frequencies, one gets less inductance. Obviously, one could use gearing to run the motor fast and the wheel slowly, but that would limit maximum speed.

An induction motor is a good choice for a solar-powered car, since the solar powered car is basically a constant load that gets driven at a constant speed. It's not so ace for a mars rover since, though you want a nice maximum speed, you also want to be able to do slow/precise positioning.

IMHO this discussion about the motor choice is 'swings and roundabouts' anyway:- Off-the-shelf coreless brushed DC motors can be 80% efficient, and a doubling of control electronics complexity for a 20% increase in efficiency doesn't seem like the greatest trade-off.

As to the people in this thread talking about brushless motors: its true that there are no brushes to wear out on brushless motors (and they have other benefits), but that mode of failure might not have been a priority at the design stage.

Reliability theory considers product failure to follow a "bathtub curve", with three modes of failure: Early failure, random failure and wear-out failure. Brushes wearing down would be a 'wear out failure'. The specification for the rovers called for 90 days of life; if the brushes are known to last longer than 90 days (which they have) there's no point in increasing the chance of a random failure during those 90 days just to extend the possible total lifetime.

To put it another way, if the specification says "90 days" it's better to have "90 days, 99% chance" than "900 days, 75% chance".

Just my $0.02,

Michael

Re:Failed brushes?

[Bing Tsher E]

DC servo motors like, say, the ones that run the capstain on tape drives, are very refined high quality 'brushed' motors. And very expensive, but you get absolute continuous control of the degree of motion, not the 'steps' of a stepper motor. You're right in your observation than in the RC hobby there probably aren't many motors of that quality being made, brushed or brushless. Let's just say that it's easier to make cheap but good-enough quality 'brushless' motors for the RC hobby than the brush types, now that the necessary additional electronics are cheap to add to the mix.

And really, brushless motors are AC drive, which is the real significant difference. AC motors are only more efficient when you have a readily available AC supply (a big house-sized dynamo somewhere connected by wires) or are willing to invest the expense/bulk of making the AC locally (an oscillator mechanism of some sort).

Re:Failed brushes?

[Rakishi]

Too complicated to work well under the conditions, eh?

An Australian adventurer wanted to drive an electrical vehicle to the south pole, not that long ago. The Solar Car motors were one of the only two considered, because of the large body of field test data and telemitry that exists for the motor design.

As a said before, anything on earth is orders of magnitude easier than Mars.

Of the LI batteries in the Rovers, _most_ of them are non rechargeable.

Do you have a link for this, everything I'm seeing says that all the batteries in the new rovers are rechargeable.

I understand the eggs and baskets arguments, but I point out that NASA has gone from being a technology Visionary circa 1965 to one of the most technologically conservative organisations circa 2000.

They had more money to spend on projects back then, now it's going towards more cheap projects instead of a few big ones. That means they need to use tested technology and still have a decent failure rate. I belvie the Voyager probes cost something like

Or are you going to tell me we should have sent Mr Armstrong to make that one small step with "Proven Technology"?

Yes. What do you think Apollo 7 to 10 were there for? Do you think they didn't reuse the technology from previous missions? And how many billions did they have to all that testing with?

A mission to the moon, involving humans and a massive budget is quite different than one to Mars involving robots and a decent budget. People can deal with problems, robots can't for example.

NASA is cutting budgets and doesn't have the money for testing. Fair enough. But innovation is cheap.

And yet you use Apollo as an example, a program that cost $25 BILLION. Seems that innovation in space isn't cheap according to your own example.

Re:Failed brushes?

[iggymanz]

maxon says the one of the two models used on the Rover is with no modification, and the other had minor mods. Since the Rovers were designed for 90 days operation, I'm sure the brush life wasn't a concern. Now that those things are still going after two years, maybe all those motors start failing at once....

Re:Failed brushes?

[Anonymous Coward]

Also, the Mars rovers aren't operating in space -- the atmosphere (thin as it is) and magnetic field of Mars do provide considerable protection (compared to a satellite or something that is in space) against things like ionizing radiation.

First of all satellites are INSIDE Earth's magnetic field and thus have considerable protection compared to deep space. Second of all the, Mars' rovers spent considerable time in transit to Mars with no outside protection at all. Third of all while there is some protection offered by Mars, it is still much worse than anything on Earth.

Re:Failed brushes?

[dougmc]

Second of all the, Mars' rovers spent considerable time in transit to Mars with no outside protection at all.

As a general rule of thumb, ionizing radiation doesn't usually immediately destroy electronic components (at least those that we've hardened for space duty) when it hits it. The damage can accumulate over time, or it can cause a `glitch' changing a 0 to a 1 in a digital circuit (which can do nasty things like crash computers (which is taken care of by watchdog systems that initiate a reboot when needed)) but things don't generally just `stop working'.

This page gives some good information on exactly what the effects are and what can be done about them.

Third of all while there is some protection offered by Mars, it is still much worse than anything on Earth.

I was wrong when I assumed that Mars had a substantial magnetic field -- it does not. But even so, the atmosphere, even being only 1% as thick as ours, would provide considerable protection. The Martian surface probably gets far less ionizing radiation than a satellite in Earth orbit would, for example.

And don't forget that the Mars rovers are controlled by computers. Computers are far more vulnerable to ionizing radiation than other forms of electronics. And really, ESCs are pretty simple, being mostly just analog components. They should be relatively resistant to ionizing radiation -- far more so than the computer components that control them. So I don't think that's really a big issue -- just protect them half as well as you protect the computer parts, and you'll be just fine. And also don't forget that the Mars rovers already almost certainly have several ESCs ... it's not like using brushless motors would add ESCs where there were none before.

Re:Failed brushes?

[njchick]

JPL should have used a steam engine. It has been around for centuries, and so must be the safest option. Actually, why didn't JPL send some horses to Mars? Now, that would really be a solution proven by milleniums of human history. One small step for a horse ...

Martian AAA

[Anonymous Coward]

I wonder if that Martian with a Squeegie is any good with tires? Might not be willing to touch it though after they stiffed him on the tip for the window job he did on the solar panels.

Re:Martian AAA

[Saeed al-Sahaf]

Let's just hope it's not the same thing that happened to Spirit Rover...

I'm still amazed....

[zappepcs]

This robot was supposed to last about 9 months... I think it has gone waaayyyy past the rated mileage for that wheel. The fact that it is free-wheeling and not a major hinderance is just a testament to how well it was actually designed. This 3x life-span thing is incredible if you take into account all of the challenges that the designers faced. I dabble in hobby robotics, and I can attest to the fact that designing a robot that does as well as it has done for as long as it has done, is a major accomplishment. Think about the warranty that you get on a new automobile... if it performed past its expected lifetime of usefulness to the tune of 300 percent, people would be driving vintage cars all over the place.... it is an amazing robot and planetary exploration vehicle!

Re:I'm still amazed....

[fishbowl]

> I think it has gone waaayyyy past the rated mileage for that wheel.

Who wants to be on the design team for the next one, after the bar has been raised this much?
Now the *expectation* will be, not a few months, but a couple of years of duty. And I wonder if the engineers responsible for Spirit and Opportunity got any negative criticism for making inaccurate projections about the duty cycle of their design and implementation? In some offices, it's just as bad to overestimate something like this as it is to underestimate -- perhaps their overdesign had budget impacts that caused other components to suffer...

I really wonder about this, but don't get me wrong -- I think it's one of the most amazing things ever that we have autonomous robots exploring Mars. But after the mission was successful, I'd kind of like to be a fly on the wall in some of the management reviews. After a while the congratulatories stop, and they start talking about the next job. And some management cultures don't respond well to things like deflated expectations, and I understand that NASA is one of those cultures...

Re:I'm still amazed....

[zappepcs]

Those are very good points, but I think that most of the reason for the unexpected longevity of the mars rovers is that they expected dust from dust storms to critically hamper the solar panel operation. What was a surprise is that the wind quite effectively kept the solar panels clear of dust, giving a much longer lifetime. I don't think that the engineers expected to have to worry about the motors lasting 36 months or more since it was not expected. Mars has quite extreme temperature swings, so the engineering is probably worth what it cost to build the rovers. Mother nature is something that just can't always be anticipated, unless, of course, you anticipate problems due to mother nature. In that case, any positive turn of fate leaves you in the position of underestimating vehicle longevity.

The temperatures, radiation, dust, vibration... these are very harsh environmental variables. It is just amazing that they are still running. I'm sure that NASA is still as amazed as we are, and pleased to be continuing the scientific research at what amounts to a budget bonanza.

You are most probably right in thinking that what was learned this time around will be incorporated in the next planetary exploration vehicles, and a longer lifetime expectation will be part of that. In line with that, recent NASA un-manned missions have been incredibly successful. I look forward to more solar system exploration, and also to commercial exploration based on NASA work.

Now that we know how to build robots to explore Mars, we can build them to explore other planets, and that ion engine thing is a Trekie's dream. The expectation bar is rising, and that is a good thing. The X-prize and similar efforts are creating huge scientific 'wealth' for all to use. Its all very cool.

Re:I'm still amazed....

[Anonymous Coward]

Mother Nature? Don't you mean an aunt or something?

Re:I'm still amazed....

[Anonymous Coward]

The robot was designed for a minimum lifespan vs. a car's average lifespan...
They probably design it to have a high degree of confident too, so the average life of the robot can easily be a few times over its minimal life span.

all alone in the cosmos

[JTW]

The rovers are interesting critters.. not unlike their older sibling Pioneer 10.

I guess we've given up on artificial intelligence, but I rather think what we altogether thought was a mind of information is actually a mind of situation and evolving spirit that simply exists in the moment. If that be true, even an Ant could have artificial intelligence.

Its interesting we drive these things into the ground, or until they run out of power, or we loose interest.

It may be lame, But I'd think it might be more interesting in the long run to upload a final survival program into these critters and turn them loose.. perhaps in the long run we'll come to those ideas and terms. Perhaps years from now when astronauts decide to land there they really will find martians!

Of course if we have a nuclear or biological melt down, then perhaps they will out live us.

There was a SciFi story long ago called NightFall.. it would make an interesting animated short or story to tell the story from the rovers perspective... and in the end they are given their freedom and continue to look up at the night to the twinkle in the sky where their makers live, and then.. they loose contact, perhaps they merely lost interest in their creations.. or perhaps the makers are no more, and they truly are all alone.. and as the cold surrounds and grips them they fold up their solar wings preparing for another martian winter and the rovers go to sleep.. perchance to dream.. of other worlds.

Re:all alone in the cosmos

[Anonymous Coward]

Oh I know. Lets stop collecting useful data for a half assed "experiment". Yeah seems like a great idea. Dumbass.

Re:all alone in the cosmos

[Viol8]

By the time we can write AI programs sophisticated enough to do what
you suggest, the rovers will be long expired.

The Truth...

[Tatarize]

They made Spirit and Opportunity do some battlebot stuff. And well, Spirit is a puss.

Re:Still a tossup - Rovers dead before Vista relea

[Anonymous Coward]

2514 AD? You are overly optimistic.

Even if it can't make it up the slope...

[artifex2004]

Why would the rover actually permanently die if it ran out of power?
Surely when the Martian winter comes to an end, and the area it's in is flooded with sunlight again, the solar cells could still work, the battery could recharge, and it could wake up?

Or did nobody think about a cold restart?

Re:Even if it can't make it up the slope...

[deong]

It's not that simple. The rovers are full of fairly sophisticated sensor packages, most of which can't handle the extremely low temperatures on the Martian surface. They need the batteries to basically, well, run the heater.

The principle investigator for the missions has written a book, "Roving Mars", that really is worth the read.

Re:Even if it can't make it up the slope...

[WoTG]

It's probably much more useful to use the rover for a few minutes a day than to let it sit idle for several months. After a long break, who knows what will break, stick, or die. The rover is well past it's best before date already, anything to reduce the stress on the machine is probably a good idea.

Re:Even if it can't make it up the slope...

[Anonymous Coward]

They were hoping that the martians would give the rover a push start...

Re:Even if it can't make it up the slope...

[ScottMaxwell]

It's not that simple. The rovers are full of fairly sophisticated sensor packages, most of which can't handle the extremely low temperatures on the Martian surface. They need the batteries to basically, well, run the heater.

Bingo. Indeed, it's even worse than that: if you can't run the heaters, all of the electronics undergo more extreme thermal cycling. This causes components to contract, flex, break, etc. Several critical components -- e.g., the CPU -- have no redundancy; if one of those goes, the whole rover goes.

This failure is the most dangerous thing to happen to Spirit since the flash anomaly on sol 18, when we effectively lost contact entirely for several days. Frustratingly, we're within sight of a safe haven -- only about a football field away -- but we might not be able to get there. Some people on the team think that if we have to drag a wheel, we can't climb the slopes we need to climb to make it to safety. I would just hate for Spirit to go this way; it would be like dying of thirst within sight of water, and she deserves better. (On the other hand, one thing I've learned is this: never bet against the rovers.)

The principal investigator for the missions has written a book, "Roving Mars", that really is worth the read.

Agreed! And since Steve's such a great guy, I'll linkify that. :-)

Also looks like it's coming out in paperback soon.

Re:Even if it can't make it up the slope...

[Mr. Freeman]

Did they have a heater when it was being shot through space to Mars? It would get just as cold if not colder while in space.

Re:Even if it can't make it up the slope...

[fishbowl]

"Surely when the Martian winter comes to an end, and the area it's in is flooded with sunlight again, the solar cells could still work, the battery could recharge, and it could wake up?"

No, after it gets too cold for too long, it will fail, according to a bit of an interview with some of the design team.

Re:Even if it can't make it up the slope...

[Anonymous Coward]

Sitting in one spot for months at a time would probably accumulate dust on the panels, maybe even bury the rover making the panels useless.

Re:Even if it can't make it up the slope...

[Tablizer]

Did they have a heater when it was being shot through space to Mars? It would get just as cold if not colder while in space.

Not necessarily. The sun heats one side and the other side gets cold. Inside the capsule would be approximately the average tempurature of the hot and cold side of the capsule. The average tempurate would depend heavily on the color and reflectivity of the capsule. I assume they picked the appropriate color for the best tempurature, for they've been facing such issues since at least the Mariner 2 probe to Venus in 1962.

I also believe the capsule had a spin so as to distribute the sun's heat more evenly.

Re:Even if it can't make it up the slope...

[Tablizer]

The rovers are full of fairly sophisticated sensor packages, most of which can't handle the extremely low temperatures on the Martian surface. They need the batteries to basically, well, run the heater.

I don't know if it is an all-or-nothing thing. The instruments might survive without battery heating, but it is simply a much larger risk.

By the way, if they cannot get to the hill in time, perhaps they could park on a boulder or dune to tilt toward the sun. However, such mini-climbs may be trickier with a bum wheel. Further, they would be stuck there in one spot for several months, whereas on the hill they can still move and explore while being tilted at the same time.

Re:Still a tossup - Rovers dead before Vista relea

[rspress]

The computer in each Mars Exploration Rover runs with a 32-bit Rad 6000 microprocessor, a radiation-hardened version of the PowerPC chip. This chip is used in IBM's heavy duty computers and is the same family of chip in the pre-intel Macs, Xbox 360, GameCube and the Cell version will run the PlayStation 3.

The chips are fairly cheap and have lightning fast floating point calculations via alti-vec. They are also very easy to program for.

NASA claimed they would only work for 90 days due to the high iron content of martian soil. In 90 days the solar cells were supposed to be covered with magnetized iron dust and the cells would not get enough sun to charge them. That never happened. Considering the cold, dusty, unsheilded environment they are in it is amazing they have lasted over two years.

Pfft, try just ONE leg...

[ChePibe]

This little guy seems to make it on his own just fine on one leg. Although, admittedly, he'll prob'bly never take him a wife.

Re:Pfft, try just ONE leg...

[Anonymous Coward]

And yet, he's got better odds than I do.

Re:Pfft, try just ONE leg...

[Silverhammer]

In order to completely understand the joke, it helps to watch this first.

Pit Stop

[SuperKendall]

Hopefully at the next Pit Stop the guys that are wiping down the solar panels will also jack it up and change out the wheel.

Ten seconds! Go!

Your sig: "annulment"

[Anonymous Coward]

"Stopping Content Restriction Annulment and Protection means not calling it DRM."

Content Restriction Annulment would be the nullification of content restriction, no? So you're offering advice on how to stop stopping content restriction? Whose side are you on again? And then there's "Protection". Why would they be protecting something at the same time they're invalidating it?

Or maybe you just don't know what "annulment" means.

All in all, a rather poor case for zealots of the information-wants-to-be-free variety, but a resounding validation of the prevailing sentiment that said zealots are rather stupid, and better ignored.

Re:Your sig: "annulment"

[Firehed]

If you want to win off-topic of the month award, at least be aware that I stole it from ZDNet so you can blame them (their inherent lack of commas tends to throw things off, but I'm lazy; get the hell over it). Give the same argument about UCE. Once it was recoined to spam (which is an acronym, by the way, self-/sales promotional advertising message), people started caring. If you like the idea of not being able to listen to your music, go on making pointless arguements. _|_

Re:Your sig: "annulment"

[Anonymous Coward]

What on earth does UCE have to do with your feeble language comprehension abilities? The ZDNet article whence originated the acronym did, in fact, use commas. So not only did you steal content from ZDNet without attribution, you also fucked it up in the process--and then, on top of it all, now you're blaming the original source for your mistake. Par for the course, for an anti-DRM zealot.

By the way, it seems that you also need to look up the definition of "inherent."

Re:Your sig: "annulment"

[Firehed]

At least get the article I used if you're going to try and use it against me. My apologies for offending an AC. If I was a zealot, you'd find that I'd have bombed the headquarters of one of the organizations that I do truly hate (and while I'd love to, I'm not a murdering lunatic). If you were able to comprehend my previous post, you'd know exactly what UCE has to do with my sig.

Re:Your sig: "annulment"

[Anonymous Coward]

"If you were able to comprehend my previous post, you'd know exactly what UCE has to do with my sig."

No, I think it's likelier you've got nothing of substance to argue, or that you're simply unable to communicate. To divine the intent of the butchery you make of logic would be like diving into sewage to retrieve your toddler's first toenail clipping. It could be done, certainly, but who would bother? No one with a life.

Re:Your sig: "annulment"

[Firehed]

I'll quote myself and remove the parenthetical statement to make it that much clearer, then: Give the same argument about UCE. Once it was recoined to spam, people started caring. Give a bad thing a stupid name and it's just geeky to discuss (heard about DRM on the news? Thought not. But what about spam? I certainly have). Give it a name that catches on, and everyone who is affected can discuss it on a non-technical level. Now go back to your cubicle at the RIAA and shut the hell up, because I'm sick of discussing the matter with a pro-DRM zealot/a grammar Nazi/someone who's talking about not having a life in the midst of an online argument. If you'd like me to change my sig, find an acronym that gets the point across better. I personally don't think 'your [music/player] is full of crap' can be easily topped, but go for it if you must.

Re:Your sig: "annulment"

[Anonymous Coward]

Aside from your nonsense assertion that "geeky" names like F-18, CD-ROM, or RSS can't catch on, and aside from the fact that pointedly referring to DRM as "C.R.A.P." is far, far geekier than you seem to realize:

"If you'd like me to change my sig, find an acronym that gets the point across better."

You could start by reinserting the commas to clarify that you aren't, after all, against nullifying content restrictions, yet also against protecting them. Needless to say, this makes you look like a dunce--an impression which (it must be said) your replies in this thread have only confirmed.

I am saddened...

[rice_burners_suck]

...to hear that the rover has lost a wheel,
though pain it does not feel.

Now it limps along the Martian soil,
alone in a great vastness of red sand and rocks.
I hope it reaches the top of the slope,
else alas for naught will it toil.
For in that vast desert there's no telephone box.
Nor much chance for hope.

Like the injured lone explorer,
Oh! What a horror!

it will suffer its demise,
Alone on that alien world,
Its nearest neighbor far away,
as no one hears its cries.
The wrath of Mars is unfurled,
And there alone will it lay.

Re:I am saddened...

[bloodstar]

For in that vast desert there's no telephone box.

Well, The Doctor could whip on over in his TARDIS and make a quick rover^w house call!

Re: I am saddened...

[gidds]

Wonderful!

(But couldn't you work in a reference to the Silv'ry Tay?)

Re:I am saddened...

[rice_burners_suck]

and then those Daleks will show up and yell "EXTERMINATE! EXTERMINATE! Must exterminate the doctor!"

I'll take the Offtopic hit for this

[LeonGeeste]

but, can someone PLEASE explain why some posters have weird margins/shorter lines, such as the one to which I'm replying?

Re:I'll take the Offtopic hit for this

[DaveAtFraud]

at the end of the line and post using HTML given the software used by slashdot. Some oher sites such as Groklaw use different software that attempts to maintain formatting in simple text posts. Use preview and see what works on different sites.

The extra credit question is: How did I get "<br>" to show up instead of being interpreted as HTML?

Cheers,
Dave

Re:I'll take the Offtopic hit for this

[chicagotypewriter]

<ecode><br><//ecode>

(minus the second slash in the closing tag. it doesnt show up otherwise, for obvious reasons)

Re:I'll take the Offtopic hit for this

[jrockway]

>
<//ecode>

No. You use &lt; and &gt; which means &lt;br&gt; converts to <br>.

Or you can use "extrans" mode, which is what I did for this post :)

Re:I'll take the Offtopic hit for this

[LeonGeeste]

Gee, thanks, moron, for explaining how to put in a line break. Too bad the question was *why* not *how*. Try again, and this time, read the fucking question.

Re:I'll take the Offtopic hit for this

[SpaceLifeForm]

It's simple
when
you
post
in plain text mode.

Re:I'll take the Offtopic hit for this

[Anonymous Coward]

"Gee, thanks, moron"

Gee, the guy was nice enough to risk his karma getting moderated offtopic to explain things to you, and all you can do is complain? What a jerk.

Re:I'll take the Offtopic hit for this

[DaveAtFraud]

Gee, thanks, moron, for explaining how to put in a line break. Too bad the question was *why* not *how*. Try again, and this time, read the fucking question.

Gee asshole, why don't you keep the discussion civil? If that's actually your STUPID question, the answer is...

Drum roll, please...

because that's the way the original poster wanted it. (DUH!)

I didn't think someone would be so utterly lacking in intelligence as to ask that question so I replied to the one technical question I thought someone might validly ask.

In the mean time, I'll see if there is some way to transfer some karma points to you. I've heard if you collect enough of them you can use them to get a clue. You obviously need one.

Cheers,
Dave

Re:I'll take the Offtopic hit for this

[LeonGeeste]

And ... why the fuck again would someone want to insert arbitrary line breaks like that?

Re:I'll take the Offtopic hit for this

[DaveAtFraud]

Why
not?

Re:I'll take the Offtopic hit for this

[LeonGeeste]

Darkie:

I was the one risking karma loss. And his "explanation" totally missed the point of what I was asking, and in a really bone-headed way that can't be explained by mere error.

Re:I'll take the Offtopic hit for this

[deesine]

Readability

Re:I'll take the Offtopic hit for this

[Anonymous Coward]

It's because he didn't think you were stupid enough to ask such a question, so he thought you meant something else. In many ways he was giving you far too much credit.

Tire tracks, not water

[tilde_e]

It is so interesting that we leave tire tracks on other planets. They may be that the first signs of life we find, or that other beings find.

Imagine the tension if we found ourselves face-to-face with a foreign martian rover!

Re:Tire tracks, not water

[Dr. Eggman]

Not quite. Martian weather is quite likly to blow away the tracks before anything found them.

You can get your Martian weather forecast here: http://astro.sci.uop.edu/~harlow/weather/mars.html

Re:Tire tracks, not water

[LeeBarnes]

Well, I, for one, will welcome our new foreign maritan rover overlords.

Re:Tire tracks, not water

[BuddhistPirate]

What if we did meet another race by rovers. Both races would try to get people on the planet as soon as they could. But what if we left the other people waiting for a decade? Would they think we stood them up?

Re:Tire tracks, not water

[tilde_e]

We could use the gimpy wheel to write "BBL" in the sand :)

Re:Tire tracks, not water

[infolib]

tire tracks on other planets. They may be that the first signs of life we find, or that other beings find.

If we're talking about Mars specifically that's not very likely. Anyone close enough to spot the rovers would long ago have noted that nearby planet emitting all kinds of radio signals and having a weird off-equilibrium content of methane in the atmosphere. In general, it's hard to imagine Earth or any other civilization sending rovers far enough that the mother planet wouldn't detect each others before they make "rover contact".

Re:Tire tracks, not water

[robogymnast]

That's why our next rover will have a circular saw attached to it, a la Battlebots!

Re:Tire tracks, not water

[chawly]

Shame - would of been the laugh of the century.

Broken this, Broken that...

[eonlabs]

One of these days, they should make enough space on the bot for equipment to repair the broken pieces. No need for a soldering iron, how about a silver marker and a jar of latex and a paintbrush. Instantly repair the broken terminals. If they're so worried about dust collecting on the solar panels, add windshield wipers or a brush or a blower. There's dozens of ways of improving the life expectancy of the bot.

PHB Response

[Golias]

It's remarkable how much longer these guys have still been alive even after they already completed their originally planned goals. Here's one thing that NASA did right.

What are you talking about? Their projections were WRONG by an order of magnitude. They should all be fired for failing to predict the life-span of these rovers accurately.

Re:PHB Response

[ctetc007]

Better to have something last 100 times longer than what you expect than to have it die on you before you reach half the life expectancy, don't you think? At least give some credit to the guys who did a hell of a job making these things so robust.

Re:PHB Response

[SEWilco]

The cost of support operations for the rovers is way over budget.

Re:PHB Response

[Golias]

Now usually, when somebody tried to riff on somebody else's joke on Slashdot, it's not even a little bit funny.

But that was hilarious. Hats off. :)

Re:PHB Response

[SEWilco]

It's also quite true. For some reason it was decided to supply additional money to keep the data flowing from the rovers. As with much comedy, making this funny was a matter of timing.

No

[ZakuSage]

Now we have an interstellar pentacycle. Looks a little something like this

3x? more like 6x!

[Anonymous Coward]

Amazing that the thing is still going. I wish this was still getting mainstream news coverage, so NASA could get the props it deserves.

Or like in Star Trek Enterprise...

[antdude]

... in one of the episodes (forgot which one -- probably Terra Prime with Peter Weller), there was a memorial scene of it on Mars.

Re:Still a tossup - Rovers dead before Vista relea

[yoprst]

If memory serves me well (and it often doesn't), Rad 6000 is something like $600000

Re:Still a tossup - Rovers dead before Vista relea

[Tablizer]

In 90 days the solar cells were supposed to be covered with magnetized iron dust and the cells would not get enough sun to charge them. That never happened.

To be fair the rovers were lucky to land in areas with lots of whirl-winds to clean them. If it was not for the whirl-winds the rovers would probably be paper-weights by now. To my knowledge, none of the Viking landers experienced a cleansing whirl-wind, and they studied Mars for about 3 years (they were powered by radioactivity).

One Wheel Dragging?

[Derling Whirvish]

One wheel dragging huh? Must be that the Mars rovers are manufactured by the same company that make the shopping carts for Walmart.

Re:One Wheel Dragging?

[Anonymous Coward]

well, perhaps the wheel problem was from a Mitsubishi Motors product?
I think the wheel will fall off pretty soon.

Re:Still a tossup - Rovers dead before Vista relea

[c_forq]

I don't know, I'm pretty sure Google^H^H^H^H^H^HSkyNet will attian self-awareness well before then. And I'm sure once the AI takes control of production it will be finished within a week.

good point

[artifex2004]

I figured it had to be something obvious I was missing :)
And the book is on my buy list, now, since you're like the 4th person to tell me it's good.
Thanks.

They'd be happy to send you!

[xiphoris]

Just make sure to give them your weight in kilograms, not pounds!

Re:Still a tossup - Rovers dead before Vista relea

[Moridineas]

Uhm, this gets informative? The Rad6000 chip runs at 20mhz according to wikipedia and 25mhz according to other sources. The chip is based on EARLY power cpu designs (think early/mid 1990s), and most definitely does NOT include any sort of altivec technology.

No radiation hardened space suitable chips are "cheap." Expect to spend tens, if not hundreds of thousands of dollars per CPU.

That's not to say it's not a great chip for what it does, but come on...

Re:Still a tossup - Rovers dead before Vista relea

[flyingsquid]

To be fair the rovers were lucky to land in areas with lots of whirl-winds to clean them. If it was not for the whirl-winds the rovers would probably be paper-weights by now.

Well, future rovers could carry around little Roombas to run around and vacuum off the top of their solar cells.

worse,

[Anonymous Coward]

intersteller pentagon

At last !

[Anonymous Coward]

goatse for vegetarians ...

You give NASA too much credit. They're liars!

[Anonymous Coward]

What do you realy think they've been doing all this time? They put a metal robot on a planet, and say it'll be dead in 9 months, all to look at rocks and perform soil analizations. Get your heads out of your asses and move your Poser T-Mobile phones from your ears! NASA contracted this project for how many hundreds of millions of George Washington voodoo dollars, and say their remote-control Radio-Shack mock-up costs how much? China has already sent people to Mars to colon-ize it. Ask 25-cent Chang about this feat (available at the customer-service center for Poser T-Mobile). NASA is working on somthing else -- somthing that needs those hundreds of millions of dollars; the project is overbid, as though they are grasping for funding sources, eerily envincing a speculation that the funds are disappearing. The only reason people didn't criticize NASA on this so-called "expensive" project on Mars is because everyone and their grandmother buys remote-control Radio-Shack cars for their brats. Who doesn't think it is neet to control a car on another planet, millions of light-years away? This isn't science, people; it funding and job security, masquerading as geological survey. I hope the Chinamen on Mars give NASA viewers a nice big Chinese asscrack smile and camera-smear just before they drop a hammer on that aluminum peice of junk that barely qualifies as being made in the United States of America.

Search for information on the Bohemian Grove; NASA engineers and public-relations people attend the Bohemian Grove convention center.

Overtime?

[DeadboltX]

"NASA is reporting that two years into its 90-day mission"

Talk about overtime, you think the rover gets time and a half now?

Uh, what?

[Drakonite]

two years into its 90-day mission

Something about that doesn't sound right to me...

Units

[Anonymous Coward]

Sounds like they still haven't figured their units out...

Re:Still a tossup - Rovers dead before Vista relea

[Anonymous Coward]

You can bet Vista can't run on them - the rovers WORK!

This is only news because NASA is incompetent

[GreedyCapitalist]

I'm happy for the success of the rovers, but I think it is pathetic that NASA's resources are so badly managed that a two-year old mission is still their showcase effort. We should be hearing about a bunch of new projects, not breakdowns on old ones. If political maneuvering didn't waste billions on the space shuttle and the ISS, we might have dozens of missions going right now. Better yet, if they let entrepreneurs keep their money instead of taking us to death, we might all be buying tickets to space.

Re:This is only news because NASA is incompetent

[puzzled]

  NASA knocked the cover off the ball with this one - 800 days on equipment meant for 90 is a big win in my book.

  I'm with you on the politics and ISS. We should cancel the shuttle, distribute the money evenly between Scaled Composites, Space-X, Bigelow Aerospace, and Virgin Galactic.

Re:Still a tossup - Rovers dead before Vista relea

[rspress]

The RAD6000 is between 200,000 and 300,000.

I could not find a price for the rad hardened Pentium chip but since Sandia is making it I don't think it will be any cheaper. I could also find no processor name for the Intel chip. A look at the wiki and it does not show any other processors than PowerPC except for an old 8bit in 1976 and a sun sparc.

If you check out the wiki entry about rad hardened chips it is quite amazing.

Re:Still a tossup - Rovers dead before Vista relea

[rspress]

That was taken into account. Remember the air there is much, much thinner and a 30MPH wind would be hard to even feel. Plus it would have to overcome the magnetic attraction. At least that was NASA claim.

The rovers have been on mars during some great mars weather. A 70MPH wind here can do a lot of damage, on mars with less air pressure 70MPH is not so bad. The winds might be enough to keep them fairly clean....if you look at the pictures they are pretty dirty but not as bad as NASA said they would be, or the iron is not sticking that well to the craft.

If you ever seen the National Geographic special about if the moon landings are fake Ralph Rene is out by a rock and dirt pile with a leaf blower showing that the moon landings were fake because he was moving dirt and rocks around with his leaf blower. This guy work for NASA and he thinks that the moon in a vacuum will react the same way as the dense air on earth.

After seeing Ralph Rene I can see the NASA people be wrong....sometime quite often.

Re:Still a tossup - Rovers dead before Vista relea

[rspress]

Yep you are correct. Sorry I was confusing the RS6000 brand of IBM chips with the RAD 6000.

I was also quoting NASA as for them being cheap. When the landers were on there way they said in interviews on TV that they were cheaper chips......looking at wiki it is hard to find many other RAD hardened chips.

winging it off the dunes

[uberdave]

"winging it off the dunes at break neck speeds" - You just reminded me of the video clip of the Jawa sandcrawler participating in the pod race.

Re:Still a tossup - Rovers dead before Vista relea

[Bing Tsher E]

In the year 2514AD both Mars Rovers will still be functioning. Their function will have been adapted, of course. They'll both be functioning as display items in a glass case in the Hard Roll Cafe, Mars .

Re:Still a tossup - Rovers dead before Vista relea

[Bing Tsher E]

Ralph Rene has probably not been fired only because of civil service and union rules.

The lethargy that is a result of labor laws is really the main thing wrong with NASA.

Clear explaination

[Anonymous Coward]

For all who are wondering what appened, an image explains better than thousand words: here it is

N.B.: Duh, server's slow :\ should be under maintenance.

Sorry folks, couldn't resist

Re:Clear explaination

[chawly]

Liked it. Still laughing.

Re:Clear explaination

[pl1ght]

HAHAHAH hilarious.

Nah, it'll be more like this...

[Anonymous Coward]

D'Ralla, one of the few remaining humans on planet Earth, stood on the wind-swept plains of what had been a verdant green valley in the United States, millions of years ago. The giant red orb of Sol, long into its slide into nova, shone down on him.

Then he shrugged, and went back to his hovel to play "Duke Nukem Forever," which had just arrived via Fed Ex Transporter that morning, its first day of release.

Traveling in a bad neighborhood

[tverbeek]

The obvious explanation is that the homeless Martians who've been walking up and cleaning off Spirit's solar panels when he stops at intersections have gotten pissed off that he keeps refusing to pay them, so they've started stealing his tires. NASA forgot the first rule of traveling in the developing world: always bring pocket money for tips, bribes, etc.

Wind alone is not enough

[Tablizer]

The winds might be enough to keep them fairly clean....if you look at the pictures they are pretty dirty but not as bad as NASA said they would be, or the iron is not sticking that well to the craft.

Generally they detected *sudden* improvements after periods of diminishing power. This would imply single strong events, probably the kind of whirl-wind dust devils spotted out on the plains (cool animations those were). In other words, wind alone does not do it, it has to be a vortex.

Re:Wind alone is not enough

[rspress]

Having been hit by my share of whirlwinds on earth, I think they get things more dusty than clean but it may be different on the red planet. With the atmosphere being much less dense than earth it is hard to say how fast or strong those winds are.

It could be that the soil was less magnetic than they thought or the winds packed more force than they thought. Even the gravity might have a helping hand as well.

While I think that the two rovers have done a great job, in fact, more than a great job, I am really waiting for the rover than will land at the edge of the mars polar cap. I think that if they ever find life on mars and I doubt they will for many reason, it will be close to where water is present. The Mars Reconnaisance Orbiter may actually do a better job than the two rovers.

Re:Wind alone is not enough

[Dastardly]

The fact that they move may also be a factor. Maybe it helps to keep the dirt from getting crusty (although that might require moisture), and thus make breezes, gusts, and whirl winds a littl emore effective.

Re:Wind alone is not enough

[rspress]

Since they move at a slow walking pace at best I doubt they could generate a breeze in the low pressure but all that bumping just might help.

Re:Still a tossup - Rovers dead before Vista relea

[spun]

Solar powered roombas. With even smaller roombas on them...

Re:Still a tossup - Rovers dead before Vista relea

[rapidweather]

Rovers dead before Vista release...
There you have it. The anticipation is what's fun, and as long as that time/date is out there, we are essentially happy.
Once it arrives, is released, etc. then we forget, and direct our attention to the next big thing that's not here yet.
Without that ability, we cease to create.

A Prediction

[berenixium]

By the time Humans get over there, it will have developed sentience, built a large array of weapons, and will be waiting for us with a rocket launcher armed and ready.

"This is for not giving me enough wheel lubricant.. BEEP.. Fire. Go Home, Humans!"

Re:Still a tossup - Rovers dead before Vista relea

[bluephone]

http://en.wikipedia.org/wiki/Radiation_hardening is the URL I assume you meant to post. :)

Re:Still a tossup - Rovers dead before Vista relea

[bluephone]

Seriously though, would it be so hard to design and install a windshield-wiper like "broom" to sweep off the solar cells? Cars had 'em decades ago. :)

Anyone have a picture of the wheel being dragged?

[Anonymous Coward]

Anyone have a picture?

Re:Still a tossup - Rovers dead before Vista relea

[rspress]

That was the one I was going to post alright;-)

Sometimes doing four or five things at the same time is not always the right way to do things, posting especially. While I can't promise I will do better next time, I will try ;-)

Who irritated you this merry morning ?

[chawly]

You,sir, are displaying the mentality of the north end of a south-bound camel. The NASA is doing what it can - and it can't go home before it announces that the robots are dead. Think of the outcry - "NASA wastes $N billions rather than show us that there are even more rocks on Mars than they thought (and we cared a jot for)" . Enquiring minds want to see pictures of rocks on Mars !! I learned this yesterday from an elderly South Korean who was telling this to her pet robot - they were waiting for the bus to go to the robot maintenance factory. I was just behind them, as I needed to get my wheels greased myself - so I was headed for the same factory

You need to go back to school - if you were ever there.

Re:Still a tossup - Rovers dead before Vista relea

[Baloo Ursidae]

Wow, a little optimistic are we? Oregon has a better shot of returning to it's pre-Californian Invasion population of 2 million than Vista has of coming out before the rovers die...

dust is a myth

[cheekyboy]

How can smart competent nasa scietists claim this 'dust on panels' crap?

When we have proof of rocks with ZERO dust on them.

Any way, isnt the atmosphere so low that it cannot support moving dust?

If there is dust, then all of the snow covered poles would be quite dusty, not 100% WHITE.

Re:dust is a myth

[rspress]

There is dust there. Since there is low gravity and low atmospheric pressure I am not sure how much of a wind it would take to lift that dust. You can see in the picture link the august 2005 self portrait of Spirt. http://marsrovers.nasa.gov/gallery/press/spirit/20 060104a/Sol583A_Deck_L456atc-A712R1_br.jpg The panels are a little dusty but not that bad. I think the rovers will still be going by the time Vista is released. However by the time Microsoft releases a version of Windows with decent security I think we will have warp drive.

Re:Still a tossup - Rovers dead before Vista relea

[Jbrecken]

If memory serves me well (and it often doesn't), Rad 6000 is something like $600000

Is it an essential component in making a bionic man?

Made in America, baby!!

[Anonymous Coward]

Only lasted 2 years? I can see they are keeping up with the trend in American made vehicles.

I don't imagine it's that hard to design a vehicle like that to last more than two years, let alone 90 days. Don't get me wrong, I am sure it is *a little* more difficult, but it surely doesn't take an incredible feat of engineering, just because it's up on Mars. They just got lucky with the Martian winds blowing shit off the solar cells, that it could still receive power to run.

Sorry, but I'm just tired of hearing everybodys jaws hitting the floor because these things are still going.

MOD PARENT DOWN!!

[Anonymous Coward]

-1, fucking racist.

Re: Biting the hand that feeds you

[Anonymous Coward]

Don't be such an obnoxious cunt.