Planetary regolith (dust) is an aggregation of various minerals and different particle sizes. Collection, storage, processing, and disposal of this material are very challenging in the harsh planetary environment. Extraterrestrial operations involving In-Situ Resource Utilization (ISRU) require conveying of regolith. The regolith needs to be transported from the planetary surface to chemical/thermal reaction vessels, and spent (processed) regolith needs to be conveyed to a disposal area.

Mechanical collection, transportation, and conveying require complex mechanisms that may be prone to mechanical degradation, discontinuous feed and disposal rates, imprecise delivery, and spillage. This, in turn, results in poor housekeeping, equipment damage, and unfulfilled mission objectives. Terrestrial mechanical conveying applications require operator intervention to control material flow. Such intervention during planetary operations may not be possible. Apparatus for moving material from one point to another without human intervention is highly complex and prone to problems with detection, identification, orientation, collision avoidance, and navigation.

Pneumatic conveying of regolith is a promising method for bulk material transport capable of performing without failure under a wide range of conditions, and provides advantages of simplicity, efficiency, and speed. The purpose of this innovation is to fluidize the regolith and entrain it in a gas stream to allow pneumatic transport through tubing, and to promote reliable, continuous material transfer from the acquisition point through processing and disposal.

A compressor provides the motive power for gas transport. The compressor supplies motive power to an eductor that entrains and suspends the regolith particles in the gas flow. This fluidization facilitates controlled transfer from the supply hopper through the transport tube to a cyclonic separator. The particles circulate around the cylindrical interior of the cyclone, eventually dropping out of the gas flow through another tube to the delivery destination. The mostly clean motive gas escapes from the top of the cyclone and passes through a filter where any remaining fine particles are removed from the gas stream. The clean gas returns to the compressor for reuse in further material transport. The eductor functions by passing the motive gas through a venturi, lowering the gas pressure in the transport tube. Lower pressure in the gas stream draws particles from the feed hopper where they are entrained and fluidized. The gas/regolith mixture flows through the transport tube to the destination.

This method enables efficient transport of material with minimal loss and less contamination of equipment and instrumentation. Closed-loop conveying allows use and reuse of scarce gas resources in a planetary location. Pneumatic regolith conveying is particularly cost-effective in conveying granular materials when a source of compressed gas already exists that can be shared with the pneumatic conveyor system.

This work was done by Ivan Townsend, Robert Mueller, and James Mantovani of Kennedy Space Center. For more information, contact the Kennedy Space Center Technology Transfer Office at 321-867-7171. KSC-13628

NASA Tech Briefs Magazine

This article first appeared in the October, 2015 issue of NASA Tech Briefs Magazine.

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