Anonymous asked in Science & MathematicsAstronomy & Space · 1 month ago

Why weren't the Mars rovers designed with treads like that are used on tanks?

I was watching a documentary on the rovers and they had issues with broken wheels, soft sand, etc. Would treads have not been better than the 6 wheel design? Also, why not some mechanism for brushing or blowing dust off the solar panels?

7 Answers

  • Joseph
    Lv 7
    1 month ago

    Unlike what most people think, a threaded vehicle can't traverse deep fine-grained soft sand.  You see video clips of dune buggies driving up and down the dunes with ease but try to do that with a tank or a bulldozer and you won't get very far.

    Debris can get into the threads and cause them to come off the guides.  On Earth reinstalling a thread is a laborious and time consuming process.  Who is going to do that on Mars?

    With Mars Rovers, the engineers solved the problem with the broken wheel by driving the rover "backward" and dragging the wheel. While it did reduce the rover's mobility somewhat, by the time the wheel broke the rover had already exceeded the planned mission duration many times over.  Despite the broken wheel the rover still managed to travel many miles.

    The engineers designed the Spirit and Opportunity rovers for a nominal mission of 90 days.  Even the most optimistic of them couldn't even dream of the rovers lasting as long as they did.  For a 90 day mission the dust build up on the solar panels wasn't considered to be a big issue.  The rovers got a boost multiple times when the wind blew the dust off the solar panels allowing them to produce more energy. 

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  • AndyF
    Lv 5
    1 month ago

    In addition to tracks being heavy and cumbersome a single track has only one drive sprocket. The loss of that motor or track makes the entire track unworkable. 

    The 6 wheel design each wheel has its own motor. Loss of a motor kills only that wheel leaving some maneuverability. Actually one rover (Spirit)had a front wheel lock up so it was pushing into soft sand. They just drove it backward and dragged the bad wheel to keep moving. 

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  • Robert
    Lv 6
    1 month ago

    The rovers are really in the desert of area 51.  Nasa can simply send someone to fix the wheel. 

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  • Remember that it took them forever to get to Mars; I think it was more than 7 years, so the technology is not that advanced.

    Also, look at modern cars for rough terrain like the Jeep. Those don't have tank wheels either. They aren't good for navigating through crevices

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  • 1 month ago

    The six Wheel design was carefully thought out

    And the wired wheels were a throw back to the Lunar Rovers

    Mars. with a slight Atmosphere has scant winds and fine dust storms which creates dunes

    The Moon has no such air, no wind and its substrate is mostly undisturbed

    Its dust is not as fine either

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  • 1 month ago

    Treads are even more complex, and add weight to the mission.  The way the rovers are folded up in their shells, treads wouldn't have been worth the engineering needed, as opposed to lighter weight wheels. 

    As for solar panels, remember - Spirit and Opportunity were only required to last 90 days on the surface.  A *great* mission would've been double that life, or about 6 months... the fact that they lasted years and years is a tribute to those who built them - but, in 90 to 180 days, the accumulation of dust on the panels wasn't considered to be an issue.  It only *was* an issue when the mission kept going and going and going and... 

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  • Anonymous
    1 month ago

    Weight and space. Every extra pound counts as an extra million dollars in launch fuel costs.

    Note that the ladder on the lunar module was basically made out of tinfoil. With gravity so low tinfoil was enough and it saved enough costs on launch to have it as light as possible.

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