NASA Lunar Regolith Sampling Conceptual Design

Last crawled date: 2 years ago

The driving principal behind this design is to deliver the required capabilities in the simplest package possible. The main body of the design (the "barrel") is open at one end to allow raw samples to be loaded in by another sub-system on the lander. This solution requires that the lander's sampling system loads many small sample into the barrel, which are each separated into two categories:
-Fine <5mm
-Goal Particles 5-20mm
-Oversized Particles >20mm

The first and second are retained and presented independently for assessment and a decision on whether to keep the sample and load it into the container, or to reject the sample and process another. The third category is automatically rejected during processing of the first two categories. Please refer to the included pdf for a graphical illustration of this process.

Motor selection was performed to meet the power and environmental considerations, combined with the goal of maximising simplicity (and hence reliability) of the system. On these grounds, a reversible, brush-less DC motor paired with a high reduction gearhead fit the bill. At 5 Watts, the Maxon 370416 is well within the power limitations and is available in a version designed for operation under hard vacuum. Operating at 6000rpm, it is paired with a 370:1 ratio gearhead to deliver low controllable speed and increase torque to ~2Nm continuous taking gearhead losses into account.

Without a detailed understanding of the properties of Lunar regolith, it is hard to know for certain, but I suspect that it may be necessary to a vibration device to the side of the barrel to assist in moving the material down and through. If this was necessary there is capacity with the mass and power budget to allow for such a device to be added.


Total Mass (409g without fasteners):
-Barrel = 274g (expect that with additional effort this could be reduced by ~50%)
-Bearings
-Kaydon Ultra-Slim x2 (1x 35mm, 1x 80mm) = 17g
-Motor and Gearhead
-Maxon BLDC Motor 370416 = 37g
-Maxon Planetary Gearhead 143996 = 81g