The Clamshell mechanism, with one quick action, acquires and retains a sample from a small body surface while minimizing sampling energy. The sampler has two quarter-sphere buckets that are driven into the small body surface. One mechanism drives a linkage that causes the two buckets to rotate about a common axis to close the buckets into each other. A benefit of this design is that one action with one actuator is used to acquire and retain the sample. Thin blades result in minimum sampling energy.
The NASA Decadal Survey identified a Comet Surface Sample Return (CSSR) as a high-priority mission for the next decade.
This innovation was developed as a candidate tool for a potential CSSR mission with a Touch-and-Go (TAG) mission architecture. In a TAG mission, a spacecraft maneuvers within several meters of the surface of a small body, and then extends a robotic arm upon which the sampling tool is located. The arm deploys the tool to the surface, and a sample is acquired in a few seconds. Then the spacecraft thrusts away from the surface of the small body.
Some of the preliminary CSSR requirements include returning a single ≥500-cm3 sample from the surface of any comet nucleus, preserving sample complex organics (sample using a “soft” technique), and preventing aqueous alteration of the sample at any time (maintain at ≤– 10 °C). The mission also could include capturing evolved gases from the sample, returning material from a depth >10 cm, and maintaining sample stratigraphy.