25 kW Power Module (ca 1978, MSFC)

The PM, or Power Module, was initially conceived by NASA’s Marshall Space Flight Center as a 25 kW regulated source of electricity to supplement the space shuttle’s fuel cells during Spacelab missions with increased electrical demand. (NASA’s Johnson Space Center had its own competing solar power system for the shuttle, called PEP.)

It would be deployed by the shuttle, serviced by the shuttle, and recovered for refurbishment by the shuttle.

Intended use was expanded to the following:

  • supplemental shuttle power during Spacelab missions
  • free-flying support spacecraft (supplying power, cooling, and guidance/communications) for longer term experiments (usually attached to SpaceLab palettes)
  • the plans to refurbish Skylab for use with the shuttle would have utilized the PM; other smaller station concepts also employed it as well


David S. F. Portree’s Wired articles and personal blog posts have been a great source of information for me.


The baseline design for the Power Module ca 1978/1979 had three primary components.

solar array support structure
contains mount points for a 59 kW solar array and thermal rejection system (radiator)
equipment rack
derived from the cylindrical base of the HST, this contained avionics, etc. in two equipment racks
berthing structure
a narrower cylindrical structure containing the CMGs and 5 berthing ports

KSP Part Mod


After giving up on a previous attempt I will attempt to make this my first KSP part with a UV map and texturing.


  • The equipment rack will be rescaled for 2.5m in-game.
  • The berthing structure be rounded off to 1.875m. (I hope that’s big enough to use 1.25m docking ports).


The 25 kW Power Module Evolution Study

This was a LMSC (Lockheed) study performed for MSFC on the power module.

Part 3: Conceptual Designs for Power Module Evolution

  1. Power Module Evolution
  2. Program Plans
  3. Cost Estimates (boring)
  4. Design Analyses
  5. Mission Accommodations
  6. WBS and Dictionary

There’s also a relevant thread on the Orbiter-Forum.


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