Global scale lunar sample return using projectiles launched from a low-flying spacecraft

Since the Moon has no atmosphere it is possible to fly over the surface at very low altitudes without experiencing drag forces. If a spacecraft flying at a low altitude were to fire a projectile into the lunar surface, a second trailing spacecraft could capture material from the resulting cloud of ejecta. This procedure could be repeated over many sites on the Moon with a fresh collector for each location. Eventually, the collector spacecraft would seal its cargo in a reentry vehicle and return to Earth with the samples. Compared with a robotic lander, the advantage of this architecture is the ability to sample locations over the entire Moon, wherever the topography will permit such maneuvers. Our crater ejecta models show that 1–10 g of material can be collected from the ejecta curtain of a 2 m radius crater at an altitude of 150 m, assuming a collector surface area of 1 square meter. We studied numerous means of creating these craters and developed two scenarios: a reduced velocity explosive excavator (EE), and a higher velocity impact excavator (IE).