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When I first designed the reference mission, I assumed we'd have a utility robot aboard. That quickly grew into a separate, precursor mission carrying an exploration robot to act as a pathfinder for the manned mission, with even more precursor missions (the microlanders described in section 5.1) to land a simplest possible camera. In this case, "simplest" means the least number of unique parts, especially moving parts. Mechanisms are fiendishly expensive.
We don't yet have a detailed weight analysis for the hab. The basic triple-Spacehab structure outfitted with the internal life support system masses 7500 lbs. We're budgeting 2500 lbs for the hab plus outfitting, for a total of 10,000 lbs landed payload. So every pound of robot will be a pound of other outfitting we can't carry. The underlying question is whether the robot is worth more than whatever mass it displaces.
The Reference Mission habitat will have a lot of spare volume. A single Spacehab module would be quite sufficient for our basic purposes -- quite a luxury of interior space compared to the Apollo Lunar Module. I designed the Reference Mission to carry a triple Spacehab so that we can expand its functions with outfitting later, and to provide a longer distance for camera relief. Photography doesn't turn out very well in cramped spaces, especially when you're photographing familiar subjects such as people. That's why pictures taken inside Apollo spacecraft give you a feeling of being very cramped even though the Apollo crews had a feelings of being inside a multi-room house. We could trade off Spacehabs for additional mission equipment, at 2500 lbs per Spacehab, at the cost of reducing interior volume and camera relief.
We also need to consider whether a robot landed at our landing site is worth as much as a robot landed somewhere else on the moon. The robots they're building at Carnegie-Mellon for the Lunar Rover Initiative are not robust enough to make a long trek before they begin their mission; though of course by the time we get the Reference Mission going, the robots will be much more mature systems.
We should consider landing robots with the Reference Mission outside the exploration base habitat. Like the Apollo Lunar Module Descent Stage, we have a lot of open space next to the descent engines. Apollo had room to put in a whole car (folded up), so surely we can find some space to put in some small robots. Again, we will be displacing other mission equipment with robots. So we still need to investigate whether the robots are worth more than a small observatory, a lunar oxygen pilot plant, more cameras, more solar arrays, seismometers, geophones, core samplers, spectroscopic equipment, radiation counters, thermometers, antennas, transmitters, tools, or whatever else we think of to carry with us. We really won't know for sure until we know enough about the design to analyze the weight of the mission equipment in great detail; then we can do the trade-offs.
In the mean time, let's keep books on our options for what we'll do with that 2500 lbs of outfitting, and include exploration robots among the options.
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