Tires on the ground ...

Note to Jim and Rob,

This discussion of NASA's shortcomings is interesting, but off topic here. If you start another thread I will move these last few posts to it. Otherwise I plan to delete them in a few days.

LB

sorry larry, got carried away.

[LB, mumbling to himself ...] "Or, perhaps some sort of jumping and/or rolling propulsion system should be used."

Have any of you seen the hampster ball comercial? The one where a small rodent is placed inside of a clear ball and is then able to move the ball around at will by walking inside the ball? A similar device is available for people, and with it one can even walk on water.

Instead of four tires, one at each corner, my cell phone sized rover might be located near the center of one tire. Hanging from an axel, a motor and gear set could be used to shift the weight of the rover package off-center, causing the (spherical )tire to roll in that direction.

Wouldn't it get sand blasted and thrown about by the wind?

I think it would be nice to do something of a "seti at home" project with it. Everyone does so many process units and for that they get a cheap screen saver of one of the marsbots camera views.

Didn't NASA hire an origami expert to design a solar panel that deployed with the pull of a thread? Flat pack origami bots that are made of memory plastic sounds a promising line of enquiry.

if the lander is impact protected by an air ball, what gas do they use? Seems a shame to just vent it when it could be used for mini hot air balloons. A good few of those would be lost though.

I came up with a drawing and then couldn't post it properly last night so I gave up and went to sleep. What I envision is a wide based tracked (basically flat) rover that is constructed so that there isn't a top or bottom.
[img]C:\Documents and Settings\Owner\My Documents\rover design.jpg[/img]

Antenna could be added to the rudder mechanism for communication to land-based repeaters for export/import of signals to orbiting satellites. Control instead of being pay per drive could instead involve small regional explorations using preprogrammed movement criteria for "everyday" judgments like obstacle avoidance. Dust storms, while violent do not move the same amount of mass as on Earth due to thinner atmosphere, this results in a quick but less damaging type of wind, high pressure, but not high volume. Still micro rovers would be subject to problems from this and could instead perhaps use them to transit large distances using deployable sails in some models. This flat model rover could avoid all of this totally by utilizing crater bottoms and defilade in the terrain to block the winds and then continue on the mission. Since my plan shows the need for some orbitting satellites (like Larry's suggestion) and these satellites would need to have GPS, weather prediction, and communication capabilities. The rovers themselves could not use compasses (no magnetic fields on Mars) and gyroscopes are probably too large. However, I think the human ear could help. I have personally wanted to build a vestibular feedback system based on a hanging electrode in a sphere filled with non-conductive fluid and thousands of tiny wire "hairs" along the wall. Movement of the hanging electrode in the sphere is then monitored by the computer which allows the rover to "know" its positional orientation. The rover could also tow trailers full of instruments to prepositioned areas multiplying the usefulness of the rover. These rovers could be deployed by bombing onto the surface by gliders.

Mark Vitrone

Mark Vitrone

[Stoat] " ... a "seti at home" project ... "

Yes. This idea is sort of an outgrowth of that concept. Plus, a while back I read of a plan to put ONE privately owned rover on Luna, and rent it to the highest bidder. (You have to go a <u>long way</u> to come up with something that is truely new.)

A lot of people would rather drive one of these things around on Mars than process data. Some of them can afford to pay for the priveledge. But while the sightseers are driving around some real scientific data will be collected and stored in a NASA database back here on Earth. That data will need to be processed and summarized, so there will be a need for an "@ home" component to this system.

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[Stoat] "Wouldn't it get sand blasted and thrown about by the wind?"

Don't forget about the pressure of the Martian atmosphere - about 1 percent of Earth's sea level atmospheric pressure. This means that those 200 to 300 kph Martian winds we hear about exert roughly as much force as a 2 or 3 kph spring breeze would here on Earth. There is enough energy in a Martian super-gale to pick up talcum power sized grains of sand, but not much else. A bigger problem would be from the dust covering things after the wind dies down. But even that is a small problem. I recall that tvf mentioned that this build up is less than one millimeter per century. Or was that per millenium?

The ball should probably not have a solid surface for other reasons. The cameras are inside - even a see trough surface will distort things. A solid surface that will resist puncture adds weight (but so does the mechanism to stiffen a collapsable framework ... ).

(More objections, please. One person can't think of all the problems a particular design will have to solve.)

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[Stoat] " ... &lt;folding&gt; solar panels ... "

Ah yes - the power source. This is going to be the big one. The problem that is most likely to keep this project from actually happening. (Ummm, let me rephrase that: ... the TECHNICAL problem that is most likely ... )

Solar cells and batteries. Lots of problems here, starting with the fragile nature of the cells. I'm looking for a design that can survive a fall over an arbitrarily high cliff. This would seem to rule out present solar cells. But there are some experimental plastic solar cells that might be compatible with the kind of severe service rover I'm thinking about.

I have an idea for an alternative power source. More on this later.

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[Stoat] "if the lander is impact protected by an air ball, what gas do they use?"

CO2, from the local atmosphere (a compressor would have to be added to the equipment list). If a way can be found to mount at least some of the cameras outside the tire, the the air cushion might be worth the extra weight.

Given an on-board compressor, it becomes possible to visualize a multi bag tire that can push itself by pumping air from the bag "in front" to the bag "in the rear". Probably not as efficient as the weight shift idea, though.

Another factor to consider. If the tire (air bag) is big enough and tough emough it could also serve as the re-entry and landing system. Anytime you can avoid having a mechanism that is used once and then discarded, you have achieved a large savings in total cost.

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[Stoat] " ... mini hot air balloons."

There has been some speculation about using balloons on Mars by the mainstream. Their conclusion is ... inconclusive . We should investigate it as well.

(A solar powered hot air balloon was tested here some years ago. Big, black airbag. Big. Small instrument package. Small. It worked well for a few hours, then went into some sort of thermal run-away condition. It was last seen ascending through 100,000 ft, at which point they lost track of it. I've not seen any reports since then, and do not know if any wreckage was ever recovered.)

Since my plan is for a large number of rovers to be scattered all over Mars, it seems reasonable that there would be more than one type. Four wheel rovers, mono-wheel ball rovers, hot air balloon rovers.

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Any other suggestions?

LB