Posts Tagged ‘CEV’

Wrong Way Round

February 29, 2008

I’ve just noticed something odd about the configuration of the Earth Departure Stage (EDS) and Orion, with the Lunar Surface Access Module (LSAM – which I’m now reading is to be called Altair).

After Earth Orbital Rendezvous the stack will then depart for the Moon, with the EDS (effectively the Ares V 3rd stage) providing the thrust. It’s just that the thrust is the wrong way. The astronauts will be accelerating in the opposite direction to that in which they left Earth. They will accelerate in the -x direction, rather than +x. The cone of the CEV will be accelerating blunt end first rather than sharp end first as they will for the other main acceleration phases of any mission, including transEarth injection (TEI) and reentry/landing.

I can imagine astronauts basically suspended in their harnesses as the up they were familiar with on take off becomes down. I can’t imagine it is easy to design couches that are reversible in this way.
This just doesn’t seem right. The acceleration of the EDS stack must be significant, and will be several minutes in length if it is anything like Apollo/Saturn. You’ll recall that the Apollo/Saturn TLI stack, with the SIVB pushing it, was in the same +x axis as at launch, TEI and reentry. How will astronauts cope?

So, have I just ruined a whole vehicle development programme, or am I missing something, or is the problem just not as serious as I think it must be?