Outgassing
(Redirected from Outgas)
Outgassing is an alternative name for sublimation, the process of a solid material turning into a gas due to insufficient pressure (at a given temperature) to fully maintain its solid state.[1] In the aerospace industry, organic materials are especially prone to this phenomenon.[2]
Implications
- An outgassing material is being eroded[1], which can decrease the life expectancy of spacecraft components.
- An outgassing material may condense on other spacecraft surfaces, which can impair sensor performance or change the conductivity near or on sensitive electronics.[1]
Countermeasures
- Use materials with a low tendency to outgas, such as Teflon[3].
- Cooling a material reduces outgassing.
- Keeping a material under higher external pressure reduces outgassing.
- Components can be treated according to NASA's thermal-vacuum bakeout process. (In essence, this means that they are allowed to outgas under slowly increasing temperature. The material will then be less prone to future outgassing withing this temperature range.) It is important that components be baked out separately before being integrated, otherwise they may contaminate each other in the very ways we are trying to avoid.[1]
Open issues
The Martian atmosphere has a pressure significantly lower than the +/- 250 torr used in some thermal vacuum chambers for DIY satellite building[1]. While the temperature is lower, this would seem to indicate that many common materials are not sufficiently vacuum-safe to be used on Mars without treatment.
What degree of outgassing that could be expected on Mars, for materials and equipment produced in a colony?
References
- ↑ 1.0 1.1 1.2 1.3 1.4 S. Antunes - Surviving orbit the DIY way: Testing the limits your satellite can and must match 2012. ISBN 978-1-449-31062-2 pp. 10, 30, 38.
- ↑ W.K. Tobiska - The space environment in J.R. Wertz, D.F. Everett & J.J. Puschell, eds. Space mission engineering: The new SMAD. 2011. ISBN 978-1-881883-15-9 p. 127.
- ↑ S. Antunes - DIY satellite platforms: Building a space-ready general base picosatellite for any mission 2012. ISBN 978-1-449-31060-8 p. 29
