In the new NASA Artemis program, Starship needs to transfer the crew to/from Orion. Why is this even needed?

I thought that the Starship design allows it to travel directly from Earth to the Moon without all this complexity.


2 Answers 2


In the new NASA Artemis program, Starship needs to transfer crew to/from Orion. Why is this even needed?

Because that is what NASA required for solicitation NNH19ZCQ001K_APPENDIX-H-HLS. A bidder whose proposal didn't involve transferring crew from Orion (and later, NASA's Gateway) in a Near Rectilinear Halo Orbit to the surface of the Moon and back to that NRHO vehicle would have been noncompliant and would have been rejected.

Whether the broad outline of NASA's contract (and it was broad; the three proposals that won the first phase were very different) makes sense is a different question. To comply with the contract, all three proposals did have five things in common:

  • Rendezvous with Orion/Gateway to pick up the human crew,
  • Transfer from the Near Rectilinear Halo Orbit used by Orion/Gateway so as to later land on the surface of the Moon,
  • Stay on the surface of the Moon (with life support) for a requisite period of time,
  • Have some part of the vehicle that takes off from the Moon with the crew inside, and
  • Rendezvous with Orion/Gateway to drop off the human crew.

Because that's what NASA asked for.

The mission architecture for Artemis consists of:

  • Lunar Gateway, a permanent space station in a Near-Rectilinear Halo Orbit, used as pretty much what the name says: a gateway between Earth and Moon.
  • Orion, a crew capsule to transport crew between Earth and Gateway.
  • The Space Launch System, a crew-rated superheavy lift vehicle to launch Orion. (It was also originally intended to launch Gateway and other superheavy payloads, but it seems pretty clear that commercial superheavy launchers are much better at that. The main reason for its existence now is that it is crew-rated, while e.g. Falcon Heavy is not.)
  • The Human Landing System, a crew vehicle to transport crew between Moon and Gateway (or Orion, as long as Gateway is not operational).

What NASA asked for, is the HLS: a crew vehicle to transport crew between Moon and Gateway (or Orion directly, for the first mission). The fact that SpaceX chose to bid on this contract using a vehicle that can also do things that the contract doesn't require, is a choice SpaceX is free to make. But there is nothing forcing NASA to use those capabilities they didn't ask for.

In fact, there is something forcing NASA to not use those capabilities they didn't ask for, and that's the other competitors for the contract. They would sue NASA to hell and back if NASA now all of a sudden changed the contract in a way that excludes their bids.

Remember, this is only the first phase, for development and demonstration of three flights. There will be more phases, and Dynetics, the National Team, or somebody completely new might want to bid on those phases. It would be illegal to change the requirements after the fact.

So, there are contractual and legal reasons for why NASA cannot simply change the HLS requirements.

There are also contractual and legal reasons why NASA cannot cancel SLS: Boeing has put damage clauses in the contract that essentially mean that NASA has to pay them more money to cancel the contract than to finish it. So, it would be a waste of taxpayers' money to cancel SLS.

In addition, there are political reasons for why it has to be done this way: SLS is very much a Congressional beast. It was designed in Congress for Congress. NASA depends on Congress for funding. Canceling SLS is more or less equivalent to the NASA Administrator marching into the Capitol and taking a shit on the carpet while yelling obscenities at the Congresspeople. (Which ironically wouldn't be the first time this year someone has done that, but I digress.)

However, leaving all these politics and legal maneuvering aside, there is a solid technical reason for keeping SLS and Orion: they are crew-rated. Starship / Super Heavy isn't.

Well, technically, SLS is not crew-rated yet, and SS/SH will be at some point in the future, but at the moment SLS is closer. SLS is based on proven Shuttle designs, Shuttle concepts, and Shuttle hardware. The first 16 engines for the first 4 flights have literally already safely launched crew to space and braught them back several times. SS/SH is doing loads of things that nobody has ever done before, where you even have to first figure out how to crew-rate them.

And a last thing: the Lunar Starship (I would love it if they name it "Moonship"), as proposed, can actually not bring crew back to Earth. At least not all the way to the ground, because it has no landing hardware: no body flaps, no header tanks, no heat shield. So, even though Starship / Super Heavy can do the entire mission on its own (heck, it is big enough that you don't even need a base, it can be the base – and the Gateway), this particular one that SpaceX has proposed cannot.

  • $\begingroup$ Not a downvote, but "What NASA asked for, is the HLS: a crew vehicle to transport crew between Moon and Gateway" is not quite correct. NASA asked for proposals that addressed two missions, the first of which (and apparently the more important of which) asked for a crewed transfer from Orion in an NRHO to the lunar surface and back. It was the second mission that asked for a crewed transfer from Gateway in an NRHO to the lunar surface and back. $\endgroup$ Apr 17, 2021 at 11:03
  • $\begingroup$ Thanks Jorg for a great answer, I now understand the legal and political issues. The technical side needs a few clarifications for me though: 1. The starship is also not crew rated "yet", but it is planned to be crew rated in any case regardless of moon mission, so the difference from sls is only that sls is closer to it. 2. The "moonship" doesn't have the landing heat shield and flaps only because they are removed from starship for this mission, but technically they can remain and allow landing , isn't it $\endgroup$ Apr 17, 2021 at 12:25
  • $\begingroup$ What I think would be a smart move on SpaceX and NASA side, is to allow Moonship to have the capability to return to Earth and land on it's own in case of emergency of other components. Considering that such ability comes almost free, this sounds to me like a great backup plan. $\endgroup$ Apr 17, 2021 at 12:34
  • 1
    $\begingroup$ @Vikki-formerlySean: Tearing up contracts is a good way for making sure nobody ever wants to do business with you again. Also, a good way to never get funding from Congress ever again. And a good way of getting sued six ways to Sunday. $\endgroup$ Apr 17, 2021 at 19:07
  • 1
    $\begingroup$ @Vikki-formerlySean: That is interesting. Some government contracts have a specific "Termination for Convenience" clause that allows the federal government to terminate the contract in exchange for a pre-agreed settlement. These are common enough that they have their own name (T for C) What's the point of these clauses when they could just cancel the contract without paying a settlement? $\endgroup$ Apr 17, 2021 at 19:15

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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