[X] My Assistant

[JRehling]

As plans to explore the Moon move forward, I wondered about the possible success of MER-like rovers sent to the Moon. There are a number of contrasts with Mars:

The same "drive train", in half of martian gravity, could easily carry a much larger set of instruments.

Communications would be almost instantaneous.

Rovers on the lunar near-side would ALWAYS be in radio contact with Earth. No relays necessary.

The lunar sol is 14 days.

Combine those last three points, and you could imagine HUGE (by MER standards) drives performed in a single sol. Or a large number of IDD explorations in a modest-sized area.

The rover would have to survive a lunar night. Some of the mass advantage could be put into heaters.

(Apparently) no issue with dust covering the solar panels.

No seasons. No winter.

Twice the solar power, all things being equal.

MER fans ought to drool. Downside, of course: the Moon may not be as interesting for you as Mars. But there's still plenty there to study.
Operations wise, imagine two "packs" of rovers (a pack could be as small as one rover) sent to different latitudes but the same longitude. Send one pack to someplace near the eastern limb and somewhere near the western limb, so that the fraction of the time that one pack would be in in daylight would approach unity. Have three or four teams on Earth that operate 8 hour shifts to keep each rover in constant action throughout the lunar day. When night falls on one pack, it would not be long until the other pack experienced dawn.

Without the delta-v requirements of interplanetary cruise, it should easily best the cost of MERs. For the launch cost of a New Frontiers mission, two pairs of rovers could be launched to support this kind of exploration, and could last seemingly indefinitely. Four sites with very long drives at each could explore a great variety of the lunar service.

[Phil Stooke]

The Surveyors descended most of the way to the surface braked by a rocket engine underneath the frame. In the final stage of descent the engine and its associated equipment were dropped and the spacecraft continued its descent balanced on three small "vernier" thrusters. The descent stage fell nearby. None of the landers imaged their descent stages, but they might possibly be seen by LRO. Anyway, that accounts for quite a lot of the weight difference.

Phil

[dvandorn]

The Surveyors descended most of the way to the surface braked by a rocket engine underneath the frame. In the final stage of descent the engine and its associated equipment were dropped and the spacecraft continued its descent balanced on three small "vernier" thrusters. The descent stage fell nearby. None of the landers imaged their descent stages, but they might possibly be seen by LRO. Anyway, that accounts for quite a lot of the weight difference.

Phil

You also have to remember that the Surveyors used a solid-fuel rocket engine as the main braking engine. I'm not sure, but I'd bet that there are higher-performance fuels out there that would give you more Isp for the weight than the solid fuel they used. (IIRC, they used the solid motors because it was far easier, and more mass-effective, to simply drop the motor and its casing out of the Surveyor structure after it burned out than it would have been to build tanks, piping, valves, etc., to feed liquid fuels into a braking rocket.)

The motor, again IIRC, was only abotut the size of a basketball (albeit with a nozzle attached). I have something of a hard time believing that this engine was more than 500 kg in weight -- they must have used quite a bit of fuel to power the final-stage descent thrusters, which were completely useless in terms of doing the major braking. So, I guess the solid fuel system did end up saving enough weight to make the landings possible...

-the other Doug

[mcaplinger]

The motor, again IIRC, was only abotut the size of a basketball (albeit with a nozzle attached).

The smallest current version of the Surveyor solid motor, the Star-37, has a mass of about 800 kg. It's about a meter in diameter.
See http://www.spaceandtech.com/spacedata/moto...r37_specs.shtml