Value chain · CLM-0882
In plain terms
For low Earth orbit NASA gives a voltage above which a power system may arc. For geostationary orbit it gives no equivalent voltage at all - the limits are set on how many electrons accumulate in a material and how strong the electric field inside it gets. The two orbits are not constrained in the same terms.
The claim as recorded
NASA's design guidance for geostationary orbit states its charging constraints in electron fluence and dielectric field strength rather than in bus voltage: protect dielectrics and circuits to the level of 10^10 electrons per square centimetre per 10 hours, keep dielectric fields below 100 volts per mil, treat 110 mils of grounded aluminium as usually sufficient shielding for GEO orbits, and treat dielectrics as adequately leaky at 10^9 ohm-centimetres if grounded. This guidance states no GEO bus-voltage threshold.
Evidence behind this: NASA handbook summary paper read directly in the held file. The four figures were read from a rendered page, not from the text layer, which corrupts each of them.
Scope and limits
THIS IS INTERNAL, DEEP-DIELECTRIC CHARGING GUIDANCE AND IT IS NOT A SAFE-VOLTAGE LIMIT. It does not state that any bus voltage is safe or unsafe in GEO, and it may NOT be used to clear or condemn the 40 kV of CLM-0210 or the 5 kV of CLM-0879. 100 V/mil is about 3.9 MV/m and constrains the field across an insulator, which is a function of voltage AND insulation thickness, so no bus voltage follows from it without a stated thickness this source does not give. The guidance is dated 2000 and addresses spacecraft two to three orders of magnitude smaller than any SPS design in the register. THE FIGURES ARE IMAGE-READ BECAUSE THE TEXT LAYER CORRUPTS THEM, rendering 100 V/mil as "100 V/rail".
What it assumes
No assumptions are recorded against this claim.
Where it comes from
Read on the rendered page 3 of the held file: "110 mils of aluminum (grounded) is usually sufficient for GEO orbits"; "protect dielectrics and circuits to the level of 10^10 e/cm2 per 10 hours"; "keep dielectric fields below 100 V/mil"; and "use dielectrics that are leaky (10^9 ohm-cm, and grounded, is good enough)".
Basis: GEO internal charging environment
Related records
- Answers question
- QST-043 not published in this release
Cite this
energyaperture.com/c/clm-0882
CLM-0882, Energy Aperture, as of 2000.
Connected records
Other published records linked to this one. A list, not a judgement.