3 ms·
NASA has a handbook on it: https://s3vi.ndc.nasa.gov/ssri-kb/static/resources/NASA-HDBK-4001.pdf https://s3vi.ndc.nasa.gov/ssri-kb/static/resources/NASA-HDBK..
by mglz 2y ago
NASA has a handbook on it:
https://s3vi.ndc.nasa.gov/ssri-kb/static/resources/NASA-HDBK-4001.pdf https://s3vi.ndc.nasa.gov/ssri-kb/static/resources/NASA-HDBK...
Apparently you attach all grounds to some common component, like the chassis and then you have a zero volt reference. As long as it is stable and the relative voltages to it are consistent, that should suffice for electrical systems. Handling overall charge of the craft might be a bigger challenge, but no idea how that would be handled.
- dotancohen 2y agoHow are docking spacecraft handled, which likely have a different base charge?
- ceejayoz 2y agoVenting xenon plasma. (Also important for not frying astronauts on spacewalks.) https://en.wikipedia.org/wiki/Plasma_contactor https://en.wikipedia.org/wiki/Plasma_contactor
- RandomThoughts3 2y agoProtective actions are required by the docking standard so it’s taken care of at docking but I find it very hard to find detailed information about implementations. It’s either very niche or considered sensitive enough to not be published widely. I guess they use the same solution than during EVA which is running the Plasma Contactor Units to dissipate any buildup.
- schiffern 2y agoThe docking spacecraft must follow a NASA standard[1] to avoid building up electrostatic charge. From the Commercial Crew requirements document[2]: 3.9.3.13 Integrated Space Vehicle Electrostatic Charge Control 3.9.3.13.1 LEO Charging Design Standard The spacecraft shall meet the intent of the requirements contained in NASA-STD-4005, Low Earth Orbit Spacecraft Charging Design Standard. [R.CTS.285] How the contractors achieve that might be proprietary. It looks like (at one time) SpaceX used electrically conductive paint[3] as part of their mitigations. [1] https://standards.nasa.gov/standard/NASA/NASA-STD-4005 https://standards.nasa.gov/standard/NASA/NASA-STD-4005 [2] https://ntrs.nasa.gov/api/citations/20150010757/downloads/20150010757.pdf https://ntrs.nasa.gov/api/citations/20150010757/downloads/20... [3] https://phys.org/news/2013-03-white-coating-spacex-dragon-trunk.html https://phys.org/news/2013-03-white-coating-spacex-dragon-tr...
- RandomThoughts3 2y agoYou missed this one: "International Docking System Standard (IDSS)" [0] which I actually read that before answering hence my "required by the docking standard". You will see that it says: "IDSS compliant mechanisms protect against electrostatic discharge through the soft capture system" which is to say not much. That’s still more than the previous standard for which the paragraph on ESD just says "RESERVED". [0] https://ntrs.nasa.gov/api/citations/20170001546/downloads/20170001546.pdf https://ntrs.nasa.gov/api/citations/20170001546/downloads/20...
- deleted 2y ago[deleted]
- schiffern 2y agoThis deck talks about how NASA handles overall charge on the station: https://ntrs.nasa.gov/api/citations/20110014828/downloads/20110014828.pdf https://ntrs.nasa.gov/api/citations/20110014828/downloads/20... TL;DR they dissipate charge using three Plasma Contactor Units (PCUs) on the Z1 truss, and measure it using the Floating Potential Measurement Unit (FPMU) on the S1 truss. This clamps the ISS to within 20 volts of the local plasma. https://en.wikipedia.org/wiki/Plasma_contactor https://en.wikipedia.org/wiki/Plasma_contactor https://web.archive.org/web/20060929171819/http://space-power.grc.nasa.gov/ppo/projects/iss/plasmacontactor.html https://web.archive.org/web/20060929171819/http://space-powe... https://www.nasa.gov/image-article/floating-potential-measurement-unit-mounted-truss-international-space-station/ https://www.nasa.gov/image-article/floating-potential-measur...