dietz@SLB-DOLL.CSNET (Paul Dietz) (12/11/85)
Here's a possible scheme for recovering large quantities of martian moon material at very low cost. (Question: earth's moon is to lunar as a martian moon is to ???). The idea is to erect a long kevlar cable from one of the martian moons (Phobos, say). The lower end of the cable is attached to the moon; the upper end swings around at much greater than orbital velocity. Payloads are launched by reeling in the cable, attacking a bag of rocks to the end, reeling it out again and releasing the bag at the proper time. The beauty of this scheme is that it requires almost no power and no reaction mass. Energy and angular momentum are supplied by dropping Phobos slightly closer to Mars. If the cable is long enough the payloads can escape from Mars entirely, and, if released when Phobos is on Mars's dayside, could conceivably receive enough velocity change to put them onto a transfer orbit to earth. Near earth, the bags would be intercepted by small spacecraft, steered into lunar flyby trajectories to lose speed, then brought to high orbit. This may not be feasible (for example, the cable could have to be too strong or heavy), but it should be possible to lift mass into high martian orbits by this mechanism where it could be returned to earth by solar sail or nuclear propulsion (especially if the material contains a lot of hydrogen for use as reaction mass), for a considerable saving in the velocity change the sail or rocket would have to supply. This scheme will have to end before Phobos drops onto Mars (talk about environmental impact...).