Browsing by Author "Pace, Greg"
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Item Performances of the Heat Melt Compactor System in Various Operational Scenarios(2020 International Conference on Environmental Systems, 2020-07-31) Parodi, Jurek; Trieu, Serena; Young, Janine; Pace, Greg; Martin, Kevin; Richardson, Tra-My Justine; Lee, JeffreyThe Heat Melt Compactor (HMC) system has been developed to manage the waste generated on board spacecraft during long-duration missions. The quantity and composition of spacecraft trash depends upon the mission and can have a very high daily variability. This requires a flexible system able to manage extreme waste scenarios. Most missions will generate on average about one kilograms of trash per astronaut per day, derived mainly from the spacecraft logistics supplies and consisting of clothing, food & beverage residues, packaging, paper, plastic, hygiene wipes, and many other personal or scientific items used and discarded by the crew. Uncontained and unprocessed waste is a health hazard and a habitat storage problem. However, trash also contains valuable resources such as water. HMC is designed to provide volume reduction, microbial safening and stabilization, water recovery, and radiation shielding material. The final byproduct generated by HMC is a sterilized tile with the consistency of hard plastic that can be safely handled, easily stored, and used for radiation protection. This paper provides the summary of an extensive campaign of testing performed using the HMC system to simulate different nominal and extreme operational scenarios and to generate the data necessary to finalize requirements for proto-flight hardware to be deployed to an International Space Station (ISS) EXPRESS Rack.Item A Review of Existing Policies Affecting the Jettison of Waste in Low Earth Orbit and Deep Space(50th International Conference on Environmental Systems, 7/12/2021) Parodi, Jurek; Ewert, Michael; Trieu, Serena; Young, Janine; Pace, Greg; Martin, Kevin; Richardson, Tra-My Justine; Lee, Jeffrey; Sepka, StevenThe management of waste generated onboard spacecraft during future long-duration deep-space missions will require different solutions from those currently implemented on the International Space Station which consist exclusively of collecting, storing, and returning the waste to Earth. Alternative options for managing spacecraft waste are to process it for recycling and recovery of resources, and to jettison it overboard in a solid form (such as a comapcted tile) or in agaseous form after torifaction. The waste generated during a deep-space mission is derived mainly from spacecraft logistics supplies, food and beverage residues, personal or scientific items used by the crew, human metabolic waste, and unused spare components. Uncontained and unprocessed trash is a potential health hazard and a habitat volume liability, which makes onboard long-term storage an inefficient and non-optimal option. However, the jettison of solid, processed waste appears to be an effective solution for crewed deep-space missions, leading not only to volume reduction and habitat safening, but also to considerable mass savings in the spacecraft�s propulsion system. However, the disposal of trash overboard also creates a navigation hazard for spacecraft and the potential risk of contamination of planetary bodies, interfering with the search for life. This paper investigates the requirements covered by existing policies that could affect the jettison concept of operations (ConOps) and system design.Item Thermoelectric Membrane Distillation System Engineering Design Improvement Concepts(49th International Conference on Environmental Systems, 2019-07-07) Parodi, Jurek; Lee, Jeffrey; Trieu, Serena; Pace, GregAll of the membrane distillation technologies that NASA has examined to date require external heating and cooling subsystems to drive the distillation and condensation processes. Since energy is added to the system to change liquid water into vapor, and energy is rejected from the system to convert vapor back into a liquid, a higher efficiency is achieved when the enthalpy of liquefaction is recaptured for use in supplementing the enthalpy of vaporization. The Thermoelectric Membrane Distillation (TMD) system embeds thermoelectric devices acting as heat pumps directly at the membrane surface into a self-contained device, thereby heating the rententate while simultaneously cooling the permeate. A flexible testing apparatus has been developed to quickly validate the TMD concept and to characterize different key performance parameters, which have been utilized to develop models for the design of engineering prototypes. This paper describes the validation of our proof-of-concept work, the design improvements implemented to improve performances, and the degradation of performances observed during long-duration testing.