Briana Tomboulian, a graduate student whose advisor is Professor Robert Hyers in the Mechanical and Industrial Engineering Department, has been awarded a highly prestigious fellowship from NASA’s Office of the Chief Technologist. The NASA 2011 Space Technology Research Fellowship is valued at as much as $66,000 per year for up to four years. The fellowship supports a stipend for the student and the student’s laboratory work, health insurance, tuition, fees, and an extended visit to a NASA center to work on the project. Tomboulian’s successful proposal is entitled “Damage-Tolerant, Lightweight, High-Temperature Radiator for Nuclear Powered Spacecraft.”
Better radiators enable the high speed and high power necessary for the next generation of planetary probes. The electric propulsion systems under development are much higher performance than chemical rockets, but require rejection of large amounts of waste heat. A spacecraft with a high-speed in-space propulsion system could reach Mars in a matter of weeks instead of years. When it arrives at the destination and the propulsion system is no longer active, the probe will have about 1,000 times the electrical power of current probes available for instrumentation and communications.
“Launching a spacecraft is very costly and the expense is directly related to the mass of the vehicle,” Tomboulian states in her proposal. “The heat rejection system (i.e. radiator) of a spacecraft with a nuclear-electric propulsion system (NEP) accounts for up to 40 percent of the total mass. Lightweight radiators are necessary to achieve NASA’s affordable and efficient space travel goals.”
In addition to the light-weight benefits of this carbon fiber design, the proposed radiator would allow for “high thrust capabilities at all locations in space for extended periods.” Preliminary work shows that a carbon-fiber-based radiator could meet NASA’s performance targets. What Tomboulian is proposing is the modeling and experimental investigation of a novel, lightweight, high-temperature, damage-tolerant, carbon-fiber radiator for NEP powered spacecraft.
“Reducing the radiator mass has a large impact on the vehicle mass for a NEP spacecraft, thus a significant impact on cost and performance,” writes Tomboulian. “Decreasing cost and improving performance of NEP spacecraft directly supports the goal of improving the efficiency and affordability of transportation to, from, and around space destinations.”
Engineers at UMass Amherst have developed preliminary models of a novel design for a lightweight, efficient radiator. The novel element of this design is the use of carbon fibers, wound around the heat pipes, to serve as space radiator fins.
As NASA states about its Space Technology Research Fellowships, “The goal is to provide the nation with a pipeline of highly skilled engineers and technologists to improve America's technological competitiveness. NASA Space Technology Fellows will perform innovative space technology research while building the skills necessary to become future technological leaders.” (June 2011)