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Mars Rover Spirit Down a Wheel 272

Posted by Zonk
from the little-rover-that-could dept.
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."
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Mars Rover Spirit Down a Wheel

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  • by Anonymous Coward on Saturday March 18, 2006 @11:38PM (#14950653)
    I've had worse.
  • That's what happens when you only test the wheels for 9 days.
  • by SpaceLifeForm (228190) on Saturday March 18, 2006 @11:45PM (#14950674)
    I still believe both rovers will be alive
    when and if Vista is ever released.
  • by R2.0 (532027) on Saturday March 18, 2006 @11:52PM (#14950698)
    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
    • 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.
      • 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+.

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

  • by Anonymous Coward on Saturday March 18, 2006 @11:57PM (#14950708)
    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 [youtube.com]
  • by MoFoYa (644563) <mofoya@gmail.com> on Sunday March 19, 2006 @12:00AM (#14950715)
    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.
    • 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 thin
    • 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."?

  • Cold (Score:4, Interesting)

    by MichaelSmith (789609) on Sunday March 19, 2006 @12:01AM (#14950719) Homepage Journal

    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)

      by HermanAB (661181)
      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 (Score:3, Funny)

        by Prof.Phreak (584152)
        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!)
      • --
        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."

        • Linky! [everything2.com]

          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: "I

    • Just make sure to give them your weight in kilograms, not pounds!
  • TripMaster Monkey, where are you?...
  • by HermanAB (661181) on Sunday March 19, 2006 @12:12AM (#14950742)
    Hmmm, typical NASA project, 21 months late and far over budget. :)
  • by slickwillie (34689) on Sunday March 19, 2006 @12:15AM (#14950752)
    100 mile free towing too!
  • Failed brushes? (Score:5, Interesting)

    by dougmc (70836) <dougmc+slashdot@frenzied.us> on Sunday March 19, 2006 @12:19AM (#14950761) Homepage
    "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.)

    • 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.
    • 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? (Score:3, Informative)

        by dougmc (70836)

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

        Maxon [slashdot.org] 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'

    • Re:Failed brushes? (Score:5, Interesting)

      by Anonymous Coward on Sunday March 19, 2006 @12:56AM (#14950864)
      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? (Score:5, Interesting)

      by v1 (525388) on Sunday March 19, 2006 @01:00AM (#14950877) Homepage Journal
      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.
      • 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
        • 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
      • Re:Failed brushes? (Score:5, Informative)

        by dougmc (70836) <dougmc+slashdot@frenzied.us> on Sunday March 19, 2006 @02:56AM (#14951102) Homepage
        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 [rascalscooters.com], Segways [segway.com] 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.
        • 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.

  • by zappepcs (820751) on Sunday March 19, 2006 @12:30AM (#14950792) Journal
    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!
  • by JTW (11913) on Sunday March 19, 2006 @12:39AM (#14950822)
    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.

  • by Tatarize (682683) on Sunday March 19, 2006 @12:43AM (#14950830) Homepage
    They made Spirit and Opportunity do some battlebot stuff. And well, Spirit is a puss.
  • by artifex2004 (766107) on Sunday March 19, 2006 @01:03AM (#14950886) Journal
    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?
    • by deong (88798) on Sunday March 19, 2006 @01:14AM (#14950910) Homepage
      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.
      • by ScottMaxwell (108831) on Sunday March 19, 2006 @02:14AM (#14951034) Homepage
        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 [barnesandnoble.com] that. :-)

        Also looks like it's coming out in paperback [barnesandnoble.com] soon.

      • 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.
    • 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.
  • Pit Stop (Score:5, Funny)

    by SuperKendall (25149) * on Sunday March 19, 2006 @01:28AM (#14950942)
    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!
  • by rice_burners_suck (243660) on Sunday March 19, 2006 @01:34AM (#14950950)
    ...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.

  • by tilde_e (943106) on Sunday March 19, 2006 @01:42AM (#14950967)
    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!
  • by Derling Whirvish (636322) on Sunday March 19, 2006 @02:29AM (#14951060) Journal
    One wheel dragging huh? Must be that the Mars rovers are manufactured by the same company that make the shopping carts for Walmart.
  • Overtime? (Score:4, Funny)

    by DeadboltX (751907) on Sunday March 19, 2006 @04:02AM (#14951196)
    "NASA is reporting that two years into its 90-day mission"

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

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