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Tumbleweed Rover for Marathon Martian Journeys 177

Posted by michael from the dust-in-the-wind dept.
An anonymous reader writes "A prototype Mars rover, the Tumbleweed, has completed its 40 mile trek across the Antarctic, driven only by winds even in rough terrain over eight days. While the current rovers are designed for flat, equatorial regions, the tumbleweed design is geared to cover longer distances across what many consider the more interesting and dangerous polar regions on Mars."
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Tumbleweed Rover for Marathon Martian Journeys More

Tumbleweed Rover for Marathon Martian Journeys

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  • Spaceballs!?! (Score:5, Funny)

    by Skyshadow ( 508 ) on Friday March 05, 2004 @03:14PM (#8477794) Homepage
    Oh shit, there goes the planet.

    (dives for cover)

    • Oh shit, there goes the planet.

      (dives for cover)

      Maybe they could put retired general Schwartzkopf in charge of the mission.

      "Thank you for pressing the Self Destruct Button."

  • That's no tumbleweed! (Score:5, Insightful)

    by Anonymous Coward on Friday March 05, 2004 @03:14PM (#8477798)
    More like anti-escape orb from The Prisoner.
  • That the rovers that go there will move faster than a few feet per day? (Or can't they do any better with the incredible lag due to the distance between Earth and Mars?)
    • No, it means they'll carry on trundling at a few feet a day before they eventually stumble upon the bones of Elvis.

    • Re:Does this mean... (Score:2, Insightful)

      by thestarz ( 719386 )
      I think it just goes as fast as the wind blows. You can't control the speed (or direction for that matter).

      • Re:Does this mean... (Score:2, Informative)

        by thestarz ( 719386 )
        From the article: A 6-meter diameter ball on Mars could accelerate to about 10 m/s (22.4 mph) pushed along by Martian afternoon winds of 20 m/s (44.7 mph).
      • I hope they set up some sort of GPS system, then. You're going to need to find out where you are after every dust storm.

        Fortunately, it should be possible to do it with relatively few satellites. Just three, in fact, for a base system, if all are geosynchronous.

        And the ball should have some means of getting itself out of a bowl. Maybe a high-RPM motor inside that runs off a large capacitor to give a sudden burst of torque.

        • Re:Does this mean... (Score:2, Interesting)

          by joeljkp ( 254783 )
          Their current plan is that if it gets stuck, then it becomes a "stationary sensor" (which could be valuable as well). These things would be cheap, light, and small... you could drop 50 of them. So if a few get stuck in weird places, it won't do any harm. And you get to study those weird places for a long time.
        • Actually, 3 satellites are not sufficient; there are no orbits (geosynchronous or otherwise) that are always line-of-site from the poles (where this vehicle would be used). Thus, more than 3 satellites would be required to form a GPS system, at least if you want it to always be available. I'm not really sure, but the actual number required might be 7; or more depending on how much atmosphere your signal can cut through.
          • But you probably don't need always-on: indeed, the single orbiter may be sufficient when combined with inertial systems onboard the rover.

            The reason one satelite should be enough is that I'm guesing you can just take distance measurements over a period of time. Thus, the one satelite can function as three, as long as you are willing to wait for the reading and can guestimate how you've travelled in the meantime.

    • Powered by? (Score:2, Insightful)

      by RallyNick ( 577728 )
      I wonder how it gets power. Presumably from dynamometers tapping into the rotation of the ball? Then you're using wind power for both movement and communications/sensing, I wonder if there will be enough given the 0.01 atm pressure on Mars.

    • Re:Does this mean... (Score:5, Interesting)

      by dekashizl ( 663505 ) on Friday March 05, 2004 @03:52PM (#8478164) Journal
      can't they do any better with the incredible lag due to the distance between Earth and Mars?
      The lag (~10 min) affects our real-time control ability, but much of what makes the current rovers (Spirit and Opportunity) so advanced is their autonomous navigation abilities. Ground control says something like "move 100m north" and the rover figures out how to get there, drives itself, so lag isn't an issue at all. They've just been fairly cautious so far utilizing this. As the mission gets further along and past 100% success point, you'll likely see longer autonomous drives, since there is less to lose at that point of rovers fall off a cliff.

      --
      For news, status, updates, scientific info, images, video, and more, check out:
      (AXCH) 2004 Mars Exploration Rovers - News, Status, Technical Info, History [axonchisel.net].

    • Re:Does this mean... (Score:3, Interesting)

      by Tablizer ( 95088 )
      That the rovers that go there will move faster than a few feet per day?

      That is an exaggeration. The rovers can go at least about 100 feet a day, but often stop to look around or poke rocks. Look how far Spirit [nasa.gov] has gone. It's lander is little more than a spec in this scene. I bet Opportunity will go even further per day when it moves out of the crater because there are less rocks in the way to study or stump the rover.

    • Re:Does this mean... (Score:5, Interesting)

      by shokk ( 187512 ) <ernieoporto AT yahoo DOT com> on Friday March 05, 2004 @04:12PM (#8478437) Homepage Journal
      "Oh, look...there went that interesting outcropping we could have explored. Wait, wait...no, wind still hasn't died down. Damn this is the third time around the planet and we still haven't gathered any useful data."

      What do you do for solar panels when the thing is round? Could a round panel-covered object still gather sufficient power to run the computers that will be inside, or is the wind supposed to power that as well? Off to read the article... =)

  • next up... (Score:5, Funny)

    by glen604 ( 750214 ) on Friday March 05, 2004 @03:15PM (#8477805)
    Rover Bowling!

  • Not a short-term solution (Score:5, Insightful)

    by RobertB-DC ( 622190 ) * on Friday March 05, 2004 @03:15PM (#8477814) Homepage Journal
    Along the way, the beach-ball-shaped device, roughly two meters (six feet) in diameter, used the global Iridium satellite network to send information about its position, the surrounding air temperature, pressure, humidity and light intensity to a JPL ground station.

    Note that the wind-propelled rover used an existing overbuilt satellite constellation [surrey.ac.uk] to communicate its data back to the engineers. The implication there is that the rover couldn't use the sort of non-androsynchronous communications satellite that is currently available on Mars. So unreliable communications is one notable problem.

    Also, look at the data that were being recorded... position, air temperature, pressure, humidity, and light intensity. Position is likely hard to determine without a Martian GPS system. Even so, the rest of those parameters can be deduced from current orbiters, especially "humidity". I can tell you that now -- it's somewhere close to 0%. It's a dry heat^w cold.

    The nature of the object means that those are pretty much all the sensor readings you're going to get, too... add pretty pictures to the mix, of course. But this isn't something that can bore holes in rocks or take detailed spectra of interesting spots, because there's no way to anchor the ball to the ground.

    If it can be done "fast and cheap", go for it. It might give some good close-up photos of places to send a more capable lander. But I'd suggest launching another Beagle (with airbags) first, if we're wanting best bang for the buck.

    • Re:Not a short-term solution (Score:5, Insightful)

      by Skyshadow ( 508 ) on Friday March 05, 2004 @03:19PM (#8477859) Homepage
      But this isn't something that can bore holes in rocks or take detailed spectra of interesting spots, because there's no way to anchor the ball to the ground.

      It seems to me that you could choose to stop the bestie at any time just by letting some of the air out of the bag. So long as you've remembered to include an air compressor in the design, you could just fill it back up using the local atmosphere when you were ready to get moving again.

      • Wouldn't you run the risk of having it get buried in sand/ice and then be completely immobile?
        • >Wouldn't you run the risk of having it get buried in sand/ice and then be completely immobile?

          I don't think it can get burried under sand or ice, but stuck in a deep crater it definitely can.
      • According to the NASA docs, the ability to parially deflate to stop is being planned in already.

        I'm wondering if there are still color cameras in the rover? An older document mentioned something about putting a pair of color cameras on the ends of the rotation axis but no mention was made in later documents.
    • If the rover could switch modes - blow up like a balloon or deflate to be like a more traditional rover - it could do all its tests in regular mode and only use the balloon to cover large distances between testing points.
      • And it will get itself in and out of the ball ... how exactly?

        I also imagine that the "guts" inside one of these tumbleweed balls isn't as sophisticated as a rover.
        • And it will get itself in and out of the ball ... how exactly?

          I'm just thinking out loud... but maybe eight inflatable/deflatable balloons (like a sphere divided by three planes). If they were all positioned strategically on the rover they could be inflated to make it roll, or deflated and reeled in.

    • Re:Not a short-term solution (Score:1, Insightful)

      by Anonymous Coward
      I think the better solution would be to launch a satellite to orbit Mars. It could act as a Mars to Earth signal booster - possibly even multitask as a orbital observer, like an Earth spy satellite. It could be launched as a secondary payload with a new rover.

      Antenna rotation and alignment would probably be a problem though. Don't know if it would be too hard to maintain a static location and control it from Earth.
      • I think the better solution would be to launch a satellite to orbit Mars. It could act as a Mars to Earth signal booster...

        You mean, like this [nasa.gov]?

        From the link:

        Beyond science studies of their own, orbiters have an important communications role to play. Not since Viking has NASA employed both orbiters and landed vehicles together. Today, the Odyssey and Mars Global Surveyor orbiters are helping the Spirit rover "talk" to ground controllers at JPL.

        HAND

        GTRacer
        - ...to the Moon, Alice!

    • this is an EXPERIMENT (Score:5, Insightful)

      by Vellmont ( 569020 ) on Friday March 05, 2004 @03:32PM (#8477968) Homepage
      The article says that they wanted to test the durability of the design in a cold environment. That's proven to be a success. Don't start talking about the limitations of the device based on one experiment. The point was to test how well the wind transport design will work, and track its position using a simple, cheap, and pre-existing satelite network. This test is but one test in an ongoing process.
      • I know that this was JUST A TEST, but to produce something that is useful where there are no humans to take corrective measures when it gets stuck they had better come up with some form of self propulsion for the thing.

        If the thing lands in even a small crater (like the one Opportunity is in) it will be stuck. The typical Martian winds (in a 1% atmosphere remember) won't push a beachball out of even such a small crater, much less around a rock outcrop placed in its path. So, as designed it would only be vi
        • Well, they were talking about using it at the polar ice caps on mars. I'd assume there are relatively few craters at the ice caps.

          I am a bit amazed that they think they can create something that'll have a high enough surface area/mass ration to be blown around by the very thin martian atmosphere, but still have enough radios and equipment to produce usefull information.

          How can you simulate low atmosphere martian conditions? Can you make a sealed wind tunnel with a 1% atmospere and do your test at scale?
          • "How can you simulate low atmosphere martian conditions? Can you make a sealed wind tunnel with a 1% atmospere and do your test at scale?"

            Actually I was surprised to see on one of the NASA videos that this is how they tested the balloons used in the landing system for the current rovers. They have a gigantic multi-story metal chamber that they can evacuate to near vacuum conditions (it takes hours). So I suspect they could at least do SOME realistic environment testing of this concept.

      • I may be wrong of course, but I mean if we're talking about Mars we've got an atmosphere of only 1% Earth pressure (and I am guessing, similar density). Seems if you are going to blow a balloon about on Mars its got to be carrying a very small instrument payload. And a payload that can send back something meaningful while its being tumbled about and has I guess comms problems with an orbiter seems a bit fanciful.

        • I actually wonder about the same thing. Then again I'm not a Nasa scientist or engineer and don't know how small+light you can make a usefull scientific instrument. Cameras can be very small though, and if you can deflate the baloon for a period and look around a bit it might be a wonderfull transport mechanisms for a long distance Rover.
    • Note that the wind-propelled rover used an existing overbuilt satellite constellation to communicate its data back to the engineers. The implication there is that the rover couldn't use the sort of non-androsynchronous
      [sic?] communications satellite that is currently available on Mars. So unreliable communications is one notable problem. Whoah boy! You're going pretty fast and far afield on some assumptions. Just as valid would be: Using cheap off-the-shelf commercial satellite-phone transmitters this proof-of-concept..."

      For a real Tumbleweed-type probe more specific hardware would be used. It would undoubtedly take advantage of the martian orbiters that are already in fairly polar orbits (thus the current irregular communications windows). However for now Iridium is cheap, doesn't require extra-paperwork or expensive custom hardware, and frankly they're focusing on the novel bouncy-stuff rather then the rather straightforward comms issues.

      Also, look at the data that were being recorded... position, air temperature, pressure, humidity, and light intensity. Position is likely hard to determine without a Martian GPS system. Even so, the rest of those parameters can be deduced from current orbiters, especially "humidity". I can tell you that now -- it's somewhere close to 0%. It's a dry heat^w cold.
      Um, no. Again, this is stuff that could trivially and cheaply be tossed onto a proof-of-concept, not specifically what would be included on a Mars-bound probe.

      However we DON'T know those things about Mars particularly well. Indeed after the rovers landed a bright person figured out how temperatures could be identified for the radio transmission path and it turns out the martian atmosphere is more chaotic with all kinds of thermal upwellings then had been assumed. Getting some widely dispersed numbers of local values would be useful, particularly for confirming assumptions used in interpreting remote sensing guesstimates.

      The nature of the object means that those are pretty much all the sensor readings you're going to get, too... add pretty pictures to the mix, of course. But this isn't something that can bore holes in rocks or take detailed spectra of interesting spots, because there's no way to anchor the ball to the ground.
      Well, ionization, lighting under clouds, dust volumes, "pretty pictures" of more of the place up close, particularly from non-flat parts, etc. All very valuable. Sure areology is important but there's a lot that can be learned from the surface and ground-level environment that doesn't require drilling holes.

      For comparison imagine what you can learn just walking down a street with your native senses, information that can't be gained from a spy satellite, particularly one not already calibrated for your environment. Not even manipulating anything you'll learn a lot, be able to infer and correlate a lot more. Sure a Tumbleweed probe is more limited in some sorts of sensing, on the other hand it'll likely be able to go farther and longer then a Beagle-type probe.

      If it can be done "fast and cheap", go for it. It might give some good close-up photos of places to send a more capable lander. But I'd suggest launching another Beagle (with airbags) first, if we're wanting best bang for the buck.
      The question is what bang you're looking for, and what kinda bucks you can afford.

      Beagle-type probes can do some things, Tumbleweeds look like they'll be complimentary for others. Is it more valuable to intensely study, and even interact with, a handful of flat places or get measurements of a far wider swath of the plant? At least now we know that we've got alternatives to wheeled carts for exploring.

    • Comment removed based on user account deletion

    • The implication there is that the rover couldn't use the sort of non-androsynchronous communications satellite that is currently available on Mars. So unreliable communications is one notable problem.

      More likely they used Iridium because it was there (DOD bought the lot for about $0.02 on the dollar) and it was easy to get going for a quick test. There aren't that many satelites that cover the Antarctica and it wasn't worth launching one just for the test when Iridium is already there going mostly unuse

  • I expected to see some kind of rover but... (Score:3, Funny)

    by newsdee ( 629448 ) on Friday March 05, 2004 @03:16PM (#8477821) Homepage Journal
    ...a beachball?
  • Sure, a wheel is efficient at getting maximum distance out of minimum impulse, but doesn't there need to be some kind of ratchet-like one-way mechanism so it doesn't get blown backwards?

    • Re:Tumbleweed design? (Score:3, Interesting)

      by mobiux ( 118006 )
      The point is that it goes wherever the wind takes it, so there is no backwards, just "where the wind takes it"

      Forwards and backwards imply a destination, but it is more of a journey.

  • What about... (Score:2, Funny)

    by WwWonka ( 545303 )
    ...a rover to probe the deep crevices of Uranus?

    Sorry, had too. :-)

  • Difficult task (Score:5, Interesting)

    by Doesn't_Comment_Code ( 692510 ) on Friday March 05, 2004 @03:18PM (#8477853)
    I built a robot for a class once. And after completing it, I have much more respect for the people trying to design these things.

    It's not so hard to make a robot that works. It's all the possible problems that make it hard. And if your robot happens to be on Mars when it breaks... you're SO screwed!

    All the little things... unanticipated terrain, sensor malfunction, wheel gets stuck... the list is endless. Of course, during my project I kept to the smooth carpet and just moved the robot whenever something happened. But these guys have got their work cut out for them.

    No pressure, its just a 3 million dollar robot!

    • Re:Difficult task (Score:2, Offtopic)

      by BerntB ( 584621 )
      the sig said:

      Newton, Galileo, Kepler, Dirac, Faraday, Planck, Kelvin, Maxwell and Einstein beleived in God. So do I.

      And so did Hitler... :-)

      Much fewer [atheists.org] scientists are religious -- if you compare to the general population.

      It's an old observation that if you cherrypick examples from a large data set, you can get good statistics for any thesis. Of course, that is the reason it is considered less than intellectually honest...

      Besides, "religious" is hardly a good description of Einstein [stcloudstate.edu]. Also, Newto

      • I hate it when people put things they know are controversial in signatures. For some reason moderators think the post with the sig is on topic, but anyone responding to the sig is off-topic. That's really unfair. It means if you want to get away with propaganda - all you have to do is put it in your sig instead of in your post's body and it's considered taboo for anyone to question you on it.
        • It means if you want to get away with propaganda - all you have to do is put it in your sig instead of in your post's body and it's considered taboo for anyone to question you on it.

          Nitwit Moderators -- this was more "Interesting" than "Offtopic"!

        • I can say I see your point of view, and I agree with you that it seems impossible to reply to sigs. And also let me say that I have seen several anti-religious signatures and not been able to respond to them. That is why I responded with my own signature, as you can.
          • Nah, I'll respond with an actual post.

            Until quite recently, pretty much *everybody* believed in a god. So pointing out that famous scientists did so means nothing. So did everybody else, including a number of truly terrible people. Their belief in god has nothing to do with their work in science any more than Hitler's belief in god had anything to do with his attrocities.

            Einstien's "god" that he believed in was NOTHING like the god described by any major religion. It was pretty much just "Wow, the uni

  • Broad purpose robot (Score:4, Interesting)

    by darth_MALL ( 657218 ) on Friday March 05, 2004 @03:19PM (#8477856)
    I would imagine the lack of directional control would make this unit perform very generic atmospheric readings/mapping whatever. What does that solve that an orbiter and beagle type unit combo couldn't?

  • What about crevasses? (Score:5, Interesting)

    by Hayzeus ( 596826 ) on Friday March 05, 2004 @03:19PM (#8477864) Homepage
    Or even relatively shallow craters? These would appear to end such missions prematurely. Is the plan, then, to drop multiple such probes (IE, faster/cheaper)?
    • Thats the point of dropping it on the polar caps, where it should be just a huge flat sheet of ice.

      It made it across antarctica, if you'd had RTFA.
      • 70 kilometers doesn't qualify as "making it across Antarctica".

        In fact, the prototype made it across a relatively well-mapped out ice sheet. We, on the other hand, can only do our mapping of the martian surface by satellite. A relatively shallow crater or unmapped obstruction still strikes me as being a show-stopper. This may well not be the case at all, but I'd like to know why -- maybe Surveyor has a high enough resolution that this is not an issue. If not, maybe future orbiters are planeed that do.

        • 70 kilometers doesn't qualify as "making it across Antarctica".

          It did travel 70 kilometers across the Antarctic Plateau. It doesn't say where it stopped.

          At last report it was halfway across the Indian Ocean on a course to Australia. :-)

      • Thats the point of dropping it on the polar caps, where it should be just a huge flat sheet of ice.

        Having just finished Bancroft/Arnesen's No Horizon is so Far, I'm impressed it made it. The Antarctic ice is anything but flat for large areas.
    • As opportunity has demonstrated, the most scientifically interesting places are the craters and crevasses. That's where the action is, and if you can build a robot that will naturally find these places, quickly and without direct control, you have a winner in my opinion.

      As you say, if you dropped multiple cheap inflatable probes in one go, they will go off and "find" their own interesting places. Add a "deflate" feature for when it gets there/if it crosses something interesting but flat, and there you go.

  • Astrobiology Magazine Gets its math wrong (Score:5, Informative)

    by Lew Pitcher ( 68631 ) on Friday March 05, 2004 @03:21PM (#8477874) Homepage

    The ultra-durable ball reached speeds of 30 kilometers per hour (10 miles per hour) over the Antarctic ice cap

    Do you think that someone should tell Astrobiology Magazine that 30 kph is about 18 mph? That's almost double the mph that they give the rover credit for.

  • Tumbleweeds (Score:2, Funny)

    by onyxruby ( 118189 ) *
    Why tumbleweeds? Next thing you know there are going to be giant beachball tumbleweeds by the thousands infesting that desert we call Mars. They'll be everywhere and future generations will have to see them in bad movies.
    • Next thing you know there are going to be giant beachball tumbleweeds by the thousands infesting that desert we call Mars.

      I think they are targeting the flatter polar ice caps instead of rock or dust deserts. There are probably too many places to get stuck around rocks, craters, etc. They would probably need some kind of air nozzle or rockets to get out of tight spots if they roll around rocks and crevices. But the ice caps are probably pretty flat. However, I wonder what happens if such a thing got stu

  • Rover (Score:1, Redundant)

    by blamanj ( 253811 )
    Anyone else reminded of The Prisoner [retroweb.com]? (Rover is pic in upper right corner.)

  • Pelt the planet with these things... (Score:3, Interesting)

    by mobiux ( 118006 ) on Friday March 05, 2004 @03:22PM (#8477893)
    I saw we make a bunch of them and launch them shotgun style at the planet. and let them wander around collecting data. Temp, random soil tests etc.

    Then have a mothership satelite or two orbiting trying to pic up a ready to transfer signal from the units and relay the data back to earth.
    • I keep seeing images of naughty little martian children running around with pins popping these like bubble wrap.

      BAP

      Aeriouloo: I'm telling Dad! He said not to pop any more of those. You are SO goona get grounded.

      Eiixpi: Don't be a tattle tail. I don't see why we can't pop 'em anyway.

      Aeriouloo: Dad says if all their rovers pop, the earth people might figure out we're here and try to collonize us.

      Eiixpi: What's he afraid of? They can't be that dangerous. Look at their rovers...

  • UofA alternative. (Score:5, Informative)

    by anzha ( 138288 ) on Friday March 05, 2004 @03:25PM (#8477920) Homepage Journal

    For some reason I remember back in the late 1980s the University of Arizona students considered doing something like this. Rather than simply having the wind roll it around, they thought about using pumping fluids. (iirc). They decided against the ball design for fear that it might get stuck somewhere and couldn't get out.

    Instead they came up with 'rover' that had two wheels that were inflated in pie sections. It looked like a giant axel with no car attached. It had a nonrotating middle where the instruments, etc, were supposed to be placed. IIRC, they actually tested it out in the desert.

    A quick google doesn't turn up anything. IIRC, it was called the 'Mars Ball' and I read about it in Discovery magazine circa 1988, but I might be off +/- a couple years. At the time, I loved it. It was simple, yet seemed rather well thought out and flexible.

    Anyone have any good pictures or articles online?

  • Serendipity (Score:4, Interesting)

    by Tablizer ( 95088 ) on Friday March 05, 2004 @03:27PM (#8477935) Journal
    I like this part: "[image of] The spherically-wheeled rover [tricycle with 3 ballon wheels] that inadvertently gave birth to the idea for a giant tumbleweed ball. When one of the wheels broke loose during a test, it traveled across the terrain only too well."
  • What kills me is these guys discovered this approach BY ACCIDENT -- when one of their balloon wheels fell off an earlier (traditional) prototype -- but when I described the Los Angeles to Las Vegas autonomous vehicle contest to my wife last year, I described a vehicle just like this one as the perfect choice.

    I guess I'm in the wrong business.

  • Is it going to get to Mars in 3 weeks now too? Let's do some quick rover math...

    Distance to Mars 34.65 million miles Original Rovers got there in 3 weeks according to NASA

    3 weeks (21 days) 504 hours divided by distance? 69023 miles per hour

    Those are some fast little 'ships' even if it took 6 months (180 days) it would have to travel at 8020.8333333333333333333333333 to get to mars. A year? Oh you get the point. It's a conspiracy I tell you [politrix.org]

  • Non-wheeled rovers are not new (Score:4, Interesting)

    by csoto ( 220540 ) on Friday March 05, 2004 @03:33PM (#8477990)
    There are many interesting designs that take "unguided" tours of terrain. These include the "tumblers" like the one pictured, as well as a number of "glider" or "floater" designs. The gliders are basically "hover around over a spot and go where the winds take you" approach. They often have a *little* bit of navigation capability (but are mostly at the mercy of winds). The balloon idea is pretty smart. Basically, attach a bunch of sensors along a serpentine "spine" that is attached to a helium balloon. During the day, the balloon warms up and the rover flies to a new destination (wherever the winds take it). Sensors useful in the air (radar, atmospheric, etc.) take over. At night, the helium cools and it touches back down. Sensors useful on the ground (spectrometers, RATs, etc.) now fire up. Brilliant idea because of the simplicity and cost effectiveness.

  • Hold on a second... (Score:4, Redundant)

    by Entropius ( 188861 ) on Friday March 05, 2004 @03:34PM (#8477994)
    Isn't the atmosphere of Mars only a few percent as dense as Earth's atmosphere?

    Doesn't seem like the swooshing of the diffuse Martian atmosphere would provide enough force to shove even a highly-engineered tumbleweed around...
    • The gravity is only a third of earths as well, so there'd be only a third of the friction to stop it rolling around.

      Obviously these guys, who've dedicated their lives to this field of study, seem to think it'll work. I'll take their word for it.
    • Shit, they probably never thought of that.

    • Mars atmosphere + wind (Score:5, Informative)

      by dekashizl ( 663505 ) on Friday March 05, 2004 @04:57PM (#8478912) Journal
      Isn't the atmosphere of Mars only a few percent as dense as Earth's atmosphere?

      Doesn't seem like the swooshing of the diffuse Martian atmosphere would provide enough force to shove even a highly-engineered tumbleweed around...
      From http://www.azcentral.com/arizonarepublic/local/art icles/0924clay24.html [azcentral.com]:
      The atmosphere of Mars is 96 percent carbon dioxide, about 3 percent nitrogen and 1 percent other stuff, including water vapor and a little bit of oxygen. And it is a very thin atmosphere.
      The average air pressure there is only about 1 percent of Earth's.

      However, it has enough of an atmosphere to have wind. As a matter of fact, because the atmosphere is so thin, the wind reaches very high speeds.
      ...
      In the 1970s, NASA's Viking landers found the top wind speed on Mars was about 60 mph and the average was around 20 mph.

      That's enough wind to kick up huge dust storms that can go on for weeks and cover the entire planet.
      So basically if it can "kick up huge dust storms", then presumably it can push a giant lightweight inflated ball around enough to cover some ground.

      --
      For news, status, updates, scientific info, images, video, and more, check out:
      (AXCH) 2004 Mars Exploration Rovers - News, Status, Technical Info, History [axonchisel.net].

  • We have good and bad news : (Score:5, Funny)

    by 88NoSoup4U88 ( 721233 ) on Friday March 05, 2004 @03:35PM (#8478002)
    The good news is : There -IS- life on Mars !

    ...The bad news is : Our gigantic soccerball just crushed it.

  • What about Mar's thin atmosphere? (Score:5, Informative)

    by dougmc ( 70836 ) <dougmc+slashdot@frenzied.us> on Friday March 05, 2004 @03:37PM (#8478020) Homepage
    Mar's atmospheric pressure is only about 1% of our atmospheric pressure at most.

    This means that it would require a wind about 10x as strong as here to produce the same amount of force on something like this rover.

    Fortunately, the gravity on Mars is about 1/3rd of ours, so in theory you'd need only about 1/3rd as much force to move your giant beach ball, so I guess you could get the same amount of movement on Mars as you do here with only 3x as much wind.

    (Some more thoughts along this line can be found here [x-plane.com], which is a page about a simulated plane flying on Mars.)

    Apparantly Mars does have strong winds [bbc.co.uk], so maybe this isn't as crazy as I first thought :)

    As an example, the article talks about a 20 m/s wind on Mars -- that would produce the same thrust on a stationary object as a 2 m/s wind would here on Earth -- not very much. But once the object started moving, the thrust would not drop off as fast as it does here (after all, wind won't usually push something faster than the wind is going) so if the ball was light enough, it might actually move at a decent clip. But it would have to be very light.

    • Also note that the size of the tumbleweed rover proposed for use on mars has a 6 meter diameter, basically it's a bigger sail than the earth model.

  • Mc Donald wrapper (Score:5, Funny)

    by AtariAmarok ( 451306 ) on Friday March 05, 2004 @03:44PM (#8478091)
    I vote for the rover in the form of a McDonald's cheeseburger wrapper. This will blow around across half the planet (at least until Val Kilmer's robot dog finds it and eats it)

  • Some improvement suggestions (Score:4, Interesting)

    by mnmlst ( 599134 ) on Friday March 05, 2004 @03:45PM (#8478098) Homepage Journal

    First off, to get some of the positional data in a fashion similar to using the Earth's Iridium satellite network, NASA could drop some RF triangulation devices on Mars. This seems like a cheap, viable option to me.

    I would think NASA would like to have their "tumbleweeds" stay parked when something fantastic was found. Perhaps the probe could drop anchor now and then. I'm thinking a magnetized metal disc could be dropped outside the ball and attract to an electromagnet inside the ball. When the engineers are ready to let the ball move again, they switch off the electomagnet's current. Given six disposable discs, a ball could be anchored six times and no need for a motor or drilling system.

    Also, how about a kite and harness rig? If the ball/probe needs to make a long run, it could have a harness around it attached to an axle running through it. A kite, attached to the harness, would then be launched from the probe and set it off on a faster run than just having air blowing against a ball on the Martian surface. The harness and kite could be dropped if the probe needed to "be free".

    BTW, I highly recommend actually reading the links referenced as I am already seeing a lot of duplicate comments here as in previous discussions. Moderators in particular should check those links, unless you like modding up dupes...

  • Great (Score:2)

    by El ( 94934 )
    So, what do the scientists do when they want to look at something upwind? Is exploring the planet by random walk really an optimal use of resources? Sure, this thing can collect some data, but I wouldn't make it the major focus of any investment of money or time.
    • Is exploring the planet by random walk really an optimal use of resources?

      On a planet we know practically nothing about at all yet, it comes pretty damn close.
  • Can't remember the name of it, but I think it's been discussed on slash a few times for it's amazing special effects. Does anyone know the name of that british sci fi TV show that featured some guy dressed like Logan, from logans run, and he's getting chased around by inflatable weather balloons?

    I also vaugly remember something about a town in that show.. I just remember it looking strange because the town itself looked like something out of disneyland.
    • Its called "The Prisoner" and was about a British Secret Service agent who resigned in mysterious circumstances. To find out why he resigned, an organisation kidnaps him and imprisons him within the "Village", a wierd place full of half mad people.

      It wasnt so much scifi as a surreal show, where very little made sense and nothing was explained. The village actually exists (Portmeirion [portmeirion-village.com], in Wales UK) and was built mostly by a single person over a period of 50 years. The balloon you mention is the security

  • This looks like a good idea. . . (Score:4, Funny)

    by twbecker ( 315312 ) on Friday March 05, 2004 @03:59PM (#8478248)
    but can a hamster really survive on Mars?

  • You think their great now... (Score:3, Funny)

    by plopez ( 54068 ) on Friday March 05, 2004 @04:19PM (#8478503) Journal
    But wait until you have one of those nasties chasing you down a beach and dragging you back to 'The Village'. If I had a dollar for everytime that happened to me....

    Get me off of this island!

    Yours Truly,
    No. 6

  • Lots more info (Score:5, Interesting)

    by Jafa ( 75430 ) <jafa@markante s . com> on Friday March 05, 2004 @04:22PM (#8478542) Homepage
    Nasa's site has a lot more info, especially if you do a search [nasa.gov] on their site for 'tumbleweed'.
    Some early research [nasa.gov]
    Video [nasa.gov] from June 2001.

    J

  • oh, the name... (Score:3, Funny)

    by Tumbleweed ( 3706 ) * on Friday March 05, 2004 @08:24PM (#8481033)
    I predict many fruitless searches hitting my website. :)

    Sorry in advance, folks.
  • ...Martian Fun Ball.

  • Sail Power? (Score:3, Insightful)

    by brian0386 ( 755482 ) on Friday March 05, 2004 @10:12PM (#8481640)
    Why not make a rover that is sail powered, but with a movable sail that could be lowered in order to stop. The same priciple as a sailboat, but with wheels. The rover would be able to travel long distances with minimal power usage.

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