Performance of the Gen 1 Heat Melt Compactor and Lessons Learned to Enable Further Engineering Development

摘要

The Heat Melt Compactor (HMC), a waste management technology developed at NASA Ames Research Center, was designed to process non-metabolic waste generated aboard spacecraft. The device compacts, encapsulates and sterilizes the waste in preparation for onboard storage. In addition, water present in the waste is extracted and recovered, rendering the encapsulated waste inhospitable to microbial contaminants. This water is transported to the spacecraft's water processing unit for treatment and is ultimately recycled. After processing, the product, a rigid disk referred to as a tile and composed of compacted dry waste encapsulated in plastic, can be removed from the HMC hardware and safely stored. As an alternative these disks could be used as radiation shielding; this possibility is currently being investigated. First generation hardware was completed in 2008, subsequently over 75 tiles have been produced and the unit cycled hundreds of times. In September of 2012 the performance of the hardware began to deteriorate; the recovery rate of water progressively diminished as did the ability to maintain the required system vacuum. Testing was interrupted and the equipment disassembled for maintenance and cleaning. This revealed that the interior of the hardware had been contaminated with thick deposits of caramelized and charred residue, an unexpected byproduct of waste processing. Mass balance calculations previously performed with data collected during testing had indicated a discrepancy between the mass of the compacted product tiles and that of the waste samples from which they were derived. The accumulated residue could help explain this inconsistency. This paper discusses the lessons learned from both the operation of the HMC hardware and its subsequent dismantling.