Small spacecraft have been increasing in popularity because of their low cost, short turnaround and relative efficiency. In the past, small spacecraft have been primarily used for technology demonstrations, but advances in technology have made the miniaturization of space science possible. PharmaSat is a low cost, three cube size nanosatellite spacecraft, with a biological experiment on board, built at the National Aeronautics and Space Administration (NASA) Ames Research Center (ARC). Small spacecraft present several thermal design challenges. Smaller surface area translates into power and thermal constraints. The spacecraft is thermally designed to operate colder in the Low Earth Orbit (LEO) space environment, and heated to reach the temperatures required by the science payload. The power obtained from the solar panels of limited surface area constrains the power available to heat the payload to required temperatures. The pressurized payload is isolated with low thermal conductance paths from the largely dynamic ambient temperature changes. The thermal design consists of different optical properties of section surfaces, Multi Layer Insulation (MLI), low thermal conductance materials, flexible heaters and thermal spreaders. The payload temperature is controlled with software, temperature sensors and flexible heaters. Finite Difference Analysis and testing were used to aid the thermal design of the spacecraft. Various tests were conducted to verify the thermal design. An infrared imager was used on the electronic boards to find large heat sources and eliminate any possible temperature runaways. The spacecraft was tested in a thermal vacuum chamber to optimize the thermal and power analysis, and validate and qualify the thermal design of the spacecraft for the mission.
Small class-D spacecraft thermal design, test and analysis - Pharmasat biological experiment
2009
9 Seiten, 6 Quellen
Aufsatz (Konferenz)
Englisch
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