REM@MC.LCS.MIT.EDU (Robert Elton Maas) (02/10/86)
D> Date: Wed 8 Jan 1986 10:08:31 EST D> From: Paul Dietz <dietz%slb-doll.csnet@CSNET-RELAY.ARPA> D> Subject: we could have roved Mars in 1980 I claim using 1976 HPM method Glad to get your reply. I put up a proposition, and you debated it. I'd like this to continue as a brainstorming debate (via SPACE digest so others can contribute ideas and critique/rebuttals) until we have come to agreement about what should be done on the matter of Mars. D> Getting the cart to move in a straight line is not the problem. The D> problem is avoiding boulders, holes and cliffs, which needs fast D> response or a very slow rover. I go for a slow rover, which is infinitely better than no rover at all. Boulders are easy. You have a feeler that bumps into it, immediately stopping the rover and waiting for reply from Earth before proceeding. Even if the rover bumps smack-dab into the boulder, if it has a spring-loaded bumper (such as on automobiles) it doesn't get destroyed. Holes and cliffs are more dangerous and harder to detect. Let me propose some ideas for you to critique: (1) Be very paranoid. Proceed slowly, using radar or laser to detect any depression of any size in the path ahead of the rover. Just before reaching the depression (say 2 feet from gully and 10 feet from total drop-off cliff), stop and await instructions from Earth. Proceeding slowly is needed, even with good software, so that on slippery (sandy) terrain the rover won't slide over the edge. When already on a downslope, the rover should be extra careful. Perhaps when it notices it is slipping it could jam an anchor/hook into the soil to hang on for dear life. (2) Have terrain map and avoid all very-rocky or gully-full terrain when moving large distances, swinging around into "interesting" terain at the very end of a journey to take measurements. Radar mapping similar to that used on Venus and for Earth's ocean-bottoms etc., high resolution, for the portion of terrain currently between the rover and its next target location, by an orbiter at the same time as the roving, could provide high-resolution mapping of the relevant part of Mars without spreading its ability too thin across the whole planet. Either a fleet of criss-crossing orbiters, or a few maneuverable orbiters (ion rockets with solar power) could maintain surveillance over the piece of terrain of interest. The rover could run at high speed over known-flat terrain, slowing to paranoid mode when crossing unavoidable strips of rough terrain or when nearing the target region. D> Perhaps robotic drone aircraft make more sense. The control computer D> could be placed in a synchronous satellite and could control several D> aircraft during a mission. Aircraft don't have to dodge rocks or D> holes, and we can get a topographic map from a radar orbiter. Both continued flight and takeoffs/landings are energy expensive compared to either orbiting craft or ground-roving craft. I don't see aircraft as reasonable until we have developed a very large energy supply in Mars vicinity. D> No sample taking, however, except perhaps from penetrators carried by D> the drones. I'd prefer the rover if possible. Lots and lots of sample "taking" (we don't really take, we just borrow the sample, measure it, then return it) so that we could determine the mineral content at thousands of different locations around the planet in the course of a few years of roving. I don't see that being feasible with penetrator-dropping; too expensive to carry thousands of penetrators to Mars, and besides you can't exactly pick your samples that way, you just take pot luck in some vicinity (unless you drop thousands of teeny-rovers, even more infeasible).