Mars Rover Spirit Down a Wheel 272
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."
Tis but a scratch (Score:5, Funny)
Re:Tis but a scratch (Score:5, Funny)
We thank thee Lord, that in thy merc-
C'mon ya pansy (Score:5, Funny)
Re:C'mon ya pansy (Score:2, Funny)
Conversation I never Overheard (Score:5, Funny)
Martian2: nah. It seems to have such a drive for life.
Re:Conversation I never Overheard (Score:5, Funny)
Re:Conversation I never Overheard (Score:3, Funny)
Late Breaking News: (Score:5, Funny)
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:
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:Tis but a scratch (Score:3, Funny)
Not so surprising (Score:2, Funny)
Re:Not so surprising (Score:5, Insightful)
Re:Not so surprising (Score:3, Funny)
Re:Not so surprising (Score:2, Funny)
Still a tossup - Rovers dead before Vista released (Score:5, Funny)
when and if Vista is ever released.
Re:Still a tossup - Rovers dead before Vista relea (Score:3, Funny)
Re:Still a tossup - Rovers dead before Vista relea (Score:2)
Re:Still a tossup - Rovers dead before Vista relea (Score:5, Funny)
Re:Still a tossup - Rovers dead before Vista relea (Score:3, Informative)
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.
Re:Still a tossup - Rovers dead before Vista relea (Score:2, Informative)
Re:Still a tossup - Rovers dead before Vista relea (Score:5, Informative)
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 (Score:3, Interesting)
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.
Re:Still a tossup - Rovers dead before Vista relea (Score:4, Funny)
Well, future rovers could carry around little Roombas to run around and vacuum off the top of their solar cells.
Re:I'll take the Offtopic hit for this (Score:2)
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 (Score:2)
No. You use < and > which means <br> converts to <br>.
Or you can use "extrans" mode, which is what I did for this post
At first read, I get dissapointed (Score:5, Insightful)
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 (Score:3, Interesting)
Re:At first read, I get dissapointed (Score:2)
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 (Score:3, Insightful)
Re:At first read, I get dissapointed (Score:2)
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 (Score:2)
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 (Score:2)
Re:At first read, I get dissapointed (Score:3, Informative)
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.
Or like in Star Trek Enterprise... (Score:2)
Re:At first read, I get dissapointed (Score:5, Funny)
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 (Score:2)
PHB Response (Score:2, Funny)
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 (Score:2, Funny)
Re:PHB Response (Score:2)
But that was hilarious. Hats off.
It's not "dragging" the sixth wheel (Score:2, Informative)
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 (Score:5, Informative)
http://marsrovers.jpl.nasa.gov/gallery/all/2/f/78
Re:It's not "dragging" the sixth wheel (Score:2)
Re:It's not "dragging" the sixth wheel (Score:2)
Re:It's not "dragging" the sixth wheel (Score:2)
the most obvious is one with a worm gear drive (often seen inside low rpm gearmotors)
Re:It's not "dragging" the sixth wheel (Score:2)
Re:It's not "dragging" the sixth wheel (Score:2)
Re:Your sig: "annulment" (Score:2)
Re:It's not "dragging" the sixth wheel (Score:5, Informative)
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/spir
Re:It's not "dragging" the sixth wheel (Score:2, Interesting)
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.
Only lost 1 wheel? pfft (Score:5, Funny)
http://youtube.com/watch?v=OZqVvYkCe68 [youtube.com]
Re:Only lost 1 wheel? pfft (Score:2)
Pfft, try just ONE leg... (Score:5, Funny)
Re:Only lost 1 wheel? pfft (Score:5, Funny)
heh, sorry.. had to make the joke...
Re:Only lost 1 wheel? pfft (Score:3, Interesting)
exploration will continue (Score:5, Insightful)
Re:exploration will continue (Score:2)
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 (Score:2, Funny)
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 (Score:2)
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 (Score:2)
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
Cold (Score:4, Interesting)
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 (Score:3, Funny)
Re:Cold (Score:3, Funny)
In other words, they'll use a large trebuchet to get you there (or somewhere... either way, it will be fun!)
Re:Cold (Score:2)
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 (Score:2)
Linky! [everything2.com]
Re:Cold (Score:2)
They'd be happy to send you! (Score:2)
Late breaking news? (Score:2)
2 years into a 90 day mission... (Score:5, Funny)
Shoulda got the AAA Extended Service Plan (Score:5, Funny)
Failed brushes? (Score:5, Interesting)
(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? (Score:2, Insightful)
Re:Failed brushes? (Score:2)
Re:Failed brushes? (Score:3, Informative)
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.
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? (Score:5, Interesting)
Re:Failed brushes? (Score:5, Interesting)
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? (Score:2)
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? (Score:2)
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? (Score:5, Informative)
This stuff isn't rocket science. Even things like scooters [rascalscooters.com], Segways [segway.com] and electric cars use similar technology.
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? (Score:2)
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? (Score:3, Interesting)
This page [aero.org] gives some good information on exactly what the effects are and what can be done about them.
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? (Score:2, Insightful)
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? (Score:2)
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.
I'm still amazed.... (Score:3, Insightful)
Re:I'm still amazed.... (Score:5, Insightful)
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.
all alone in the cosmos (Score:3, Interesting)
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.
The Truth... (Score:5, Funny)
Even if it can't make it up the slope... (Score:4, Interesting)
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... (Score:5, Informative)
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... (Score:5, Informative)
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.)
Agreed! And since Steve's such a great guy, I'll linkify [barnesandnoble.com] that. :-)
Also looks like it's coming out in paperback [barnesandnoble.com] soon.
good point (Score:2)
And the book is on my buy list, now, since you're like the 4th person to tell me it's good.
Thanks.
Re:Even if it can't make it up the slope... (Score:2)
Pit Stop (Score:5, Funny)
Ten seconds! Go!
I am saddened... (Score:4, Funny)
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... (Score:2)
Well, The Doctor could whip on over in his TARDIS and make a quick rover^w house call!
Tire tracks, not water (Score:5, Insightful)
Imagine the tension if we found ourselves face-to-face with a foreign martian rover!
Re:Tire tracks, not water (Score:4, Informative)
You can get your Martian weather forecast here: http://astro.sci.uop.edu/~harlow/weather/mars.htm
One Wheel Dragging? (Score:4, Funny)
Overtime? (Score:4, Funny)
Talk about overtime, you think the rover gets time and a half now?
Re:Great... (Score:2, Funny)
Re:Great... (Score:5, Funny)
Re:Martian AAA (Score:2)