1. Is the power supply system redundant in launch vehicles?
  2. If so, how is it achieved? For example, is there redundancy at the battery pack level or converter level?
  3. How much battery packs will there be, like a single battery pack for all the application or separate battery packs for each application?
  4. How is the battery selected? Like, lowest energy density battery for all applications or anything else?

1 Answer 1


Up-front caveat: Crewed spacecraft, and the Shuttle in particular, may differ from other booster systems.

1 & 2. The shuttle's power system was triple redundant. Three power supplies powered three independent electrical bus networks. The buses could be interconnected to work around power supply failures.

  1. The shuttle didn't have batteries but instead generated its power from cryogenic oxygen and hydrogen using fuel cells.

  2. Fuel cells were selected for the shuttle based on power load, mission duration, and packaging requirements. (see also Why didn't Gemini, Apollo or STS use solar panels?)

enter image description here

There were redundantly powered "essential" and "control" buses not shown on this diagram as well.


DA = Distribution Assembly

AC = Alternating Current

For FLC/FPC/FMC type buses:

F / M / A = Forward / Mid / Aft

P / L / M = Power / Load / Motor

C = control

Source: 1982 Space Shuttle press reference


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