After collecting valuable engineering and science data at the Apollo 11 site, Astrobotic’s next missions will send rovers to scout the lunar polar sites of most interest to NASA and other space agencies. The Moon’s poles offer two valuable resources – persistent sunlight and the possibility of water and other volatiles trapped .
New data from the Lunar Reconnaissance Orbiter show that polar volatiles also exist in partially shadowed regions outside of crater floors. These deposits are covered by an insulating layer of dry soil that keeps the heat from occasional sunlit periods from sublimating the ices below. Astrobotic has completed a NASA contract to design an excavator to remove the covering layer. Because operations in partially shadowed regions can be done with solar power at certain times, they will be less expensive than working in permanently dark crater floors that may require costly and hard-to-commercially-license nuclear systems.
Water and other volatiles can be transformed into propellant to refuel spacecraft for their return to Earth — at least doubling the productivity or halving the cost of human lunar expeditions.
Astrobotic’s rovers will collect detailed maps of the terrain and soil characteristics at the poles, as well as data on how various components (wheels, motor seals, anti-dust coatings) perform. This advance knowledge will greatly reduce the risks and uncertainties faced by space agency planners and aerospace corporations around the world. They will be able to design human outposts, pressurized human rovers and other machinery for the actual conditions at the poles.
Another top goal will be to confirm that polar locations with near-constant sunlight exist. This is a primary reason that space agencies plan their future outposts for the poles. The equatorial regions visited by the six Apollo missions experience 14 days of sunlight followed by 14 days of extremely cold night when solar cells don’t generate power. Surviving that two-week night requires storing a great deal of power, or the complications of bringing nuclear power generators. (The Apollo missions arrived just after local dawn, and blasted off for Earth a few days later, well before the extreme heat of noontime; none attempted to survive the night.)
The Sun clocks around the horizon at the lunar poles. The Moon has a very slight axial tilt compared to the 23-degree axial tilt of the Earth; therefore the Moon’s polar regions do not experience the months of winter darkness that Earth’s polar regions do. Maps compiled by orbital missions indicate that parts of the Shackleton Crater rim at the Moon’s south pole, for example, have persistent sunlight, with periods of only two to three days when local terrain casts shadows over a location. Storing enough energy to last a two-day eclipse is far easier than girding for a two-week eclipse at the Moon’s equator. Selecting a polar location for persistent solar energy is similar to selecting a plant site in a state with cheap electrical power.
Future Astrobotic missions then will prospect for water and other volatiles. Finding the richest deposits would be a tremendous boon to space agency planners – water can be used both for life support and for generating rocket propellant for the return trip to Earth.
