In this website (scroll to the bottom), it mentions that

” Nixon’s advisors and NASA officials shifted their attention to developing a new transportation system to low Earth orbit. Options included a modified Apollo, Big G, and a winged space plane referred to as a space shuttle.”

I get Big G (Big Gemini), and I get this “winged space plane…space shuttle”, but what was this modified Apollo option?
I tried looking up Modified Apollo Rocket and could find nothing relevant.


1 Answer 1


It likely refers to the MODAP (MODified APollo) aka Apollo Logistics module.

This was a proposal for modifying the Command Module to support six crewpersons and adding cargo space to the Service Module (by downsizing the SM power and propulsion systems).

The MODAP CSM would have a stripped-down SM and a beefed-up CM. Because it would spend a limited amount of time in free flight before it docked with an Earth-orbiting station, the MODAP SM could dispense with or minimize many Apollo lunar SM systems. Batteries would replace fuel cells, for example, and a compact LEM descent engine could replace the SPS. The LEM engine would draw its propellants from a pair of spherical tanks in the MODAP SM's central cylindrical compartment. These deletions and additions would free up four of the MODAP SM's triangular bays for cargo transport.

...a 24-man space station with full crew rotation every six months would need to receive a MODAP CSM bearing six astronauts and 5855 pounds of cargo ...


  • CM = Command Module
  • CSM = Command and Service Module
  • LEM = Lunar Excursion Module
  • SM = Service Module
  • SPS = Service Propulsion System

Details here https://www.wired.com/2012/04/apollo-space-freighter-1963/

There's an extremely similar article by the same author here http://spaceflighthistory.blogspot.com/2015/11/space-station-resupply-1963-plan-to.html which includes a schematic drawing of the capsule.

schematic of 6 person Apollo

Quoted material comes from both articles - there is a lot of overlap, but the one at the 2nd link seems more to the point.

  • $\begingroup$ That article refers to an NAA doc; I found a forum post that suggested it was on NTRS with a doc number of 1974073531 -- possibly no longer publicly available? $\endgroup$ Jul 6, 2023 at 23:50
  • 1
    $\begingroup$ @RussellBorogove The only MODAP references I could find in NTRS were just brief mentions in a multivolume 1968 document called "Integrated Manned Interplanetary Spacecraft Concept Definition" Seems to be mostly a requirements document rather than a vehicle description. $\endgroup$ Jul 6, 2023 at 23:52
  • 1
    $\begingroup$ @OrganicMarble, I'm not sure of the specifics, but I'm fairly sure they were going to modify the apollo command modules for use in LEO once Skylab was in full swing. Sorry, don't have a citation for that, so take it with a heavy pinch of delicious iodized salt. $\endgroup$ Jul 10, 2023 at 4:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.