Tires on the ground ...

In your drawing of the ball rover, can you -

Remove the trailing stick from the center
Add two trailing sticks, from axel extensions on each side
Put the two halves together
Make them solid and transparent (flatten the bottom slightly)
Replace the central ball with a rectangular package that is hanging from the axel.

<b>[mafischer] "Rather than depend on GPS-like positioning for rover navigation, I recommend that the rovers navigate strictly from commands and inputs from local sensors. Determination of rover locations on the Martian surface can be accomplished using a small set of data-relay satellites, each equipped to perform bidirectional ranging to individual rovers (facilitated by a transponder function in the rover communication software). Approximate determination of rover position will require several orbital passes, and positional accuracy will improve with time-on-site."</b>

NASA probably won't be thinking along these lines until serious plans for a manned mission are on the table. So whatever we do about navagation will need to fit into the ultra cheap paradigm I've been suggesting. I guess even a low budget GPS-like system doesn't really fit this model.

Some cruise missles use photographic landmark recognition for navagation. Do you think this would work for us, given the new high resolution satellite pictures? And the very slow speed of our vehicles.

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<b>[mafischer] "Once located, maintaining knowledge of rover position is fairly simple, due to the low speed of the rovers across the Martian surface."</b>

FYI, my target speed for the four wheel rover is about 1 kph. For the ball rover, perhaps 2 or 3 kph. (The much larger wheel of the ball design ought to allow for a higher speed. The real limit is how far the rover can be allowed to travel in the 8 to 40 minutes of round-trip travel time for the control signals, and how often we can afford to update them.)

<b>[mafischer] " Another advantage of this approach is that the complex calculations are done on earth, hence the location function has minimal impact on the computational and energy budgets of the rovers and relay satellites."</b>

If a rover pilot has a map (created from a hires photo) of the area near his rover, and the rover can image / lase / echo-range / &lt;other sensor&gt; the craters / hills / boulders / &lt;other terrain features&gt; in its vacintity, it ought to be possible for the pilot to mark a path around the obstacles, transmit that path to the rover, and the rover should be able to follow the path, perhaps with minor adjustments based on input from very short range sensor data to avoid small rocks, gullies, etc. Hmmm. It might be a good idea to give the rovers a "burst mode" speed option, allowing them to move faster than normal for short distances. Like "rocking" (shifting rapidly between forward and reverse) a car. To enable them to get un-stuck.

For a ball rover traveling at 3 kph, and a round trip signal time of 40 minutes, the pilot would need to be able to lay out a path at least 2 kilometers long for the rover to be able to move continuously. The pilot would need to keep extending this path in real time, always keeping it at least 2 km long.

If the rover gets to the end of the pilot's path, it has to stop.

LB

BTW, do you see any tie-in with Stoat's idea? As I understand it, he is talking about a "map drawing" program that will create virtual roads that might (or might not) lead to/from areas of interest.

Something like this? The ball diameter is a metre.



(edited) Oh, it's just struck, i've never seen an American with a brolly. So tha automatic umbrella will be a novelty. It's about 30 cms long and is sprung loaded so that the whole thing jumps open at the press of the galm, to a metre in diameter and a handle of about a metre.

If we fire them out of the lander and get one half to open first, then that's a sort of Mary poppins parachute.

Put the trailing sticks on the outside of the hemispheres.
Move the hemispheres together to form a sphere.
(The sphere will be a soft plastic ball that is inflated)

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For a parachute to be useful on Mars (at slow speeds) it would need to be very big. The bouncing ball idea that NASA used for landing the rovers is probably more practical.

I have several spring loaded umbrellas. They are common on this side of the pond.

is this it? The load package looks bigger than it actually is, that's because I've not yet made the glass thick.