Playing Musical Chairs With SLS Launch Vehicles
Keith’s note: Sources report that NASA is looking at using the EM-2 SLS launch vehicle for the EM-1 mission due to hydrogen tank issues on the EM-1 vehicle. NASA is also looking at using the EM-3 SLS launch vehicle to fly the EM-2 mission. In addition, NASA is considering a delay in issuing the SLS block buy procurement notice (EM-3 and beyond) originally due out in June into Oct 2017 i.e. pushing its issuance into FY 2018. No one knows that NASA’s budget will be for FY 2018. Stay tuned.
NASA Decides Against Putting Crew On EM-1, earlier post
How far along is assembly of these vehicles? If they are talking about using the EM-2 “vehicle” I would assume at the very least that the EM-1 H2 tank has already been incorporated into the the tankage structure, and that this process is difficult to undo? Otherwise we would just be talking about swapping H2 tanks from EM-2. If they are actually considering using the EM-3 vehicle for EM-2, it sounds like that the first SLS core has been properly botched.
If the first SLS core has serious problems, it wouldn’t be unprecedented. After the Apollo 1 fire, they found a very large number of problems with the Block I CSM design. So many that some people felt the fire prevented a fatal accident in flight. (Which isn’t any consolation for a fatal ground accident, just evidence that version 1.0 of a complex system may not be safe to fly.)
So if they use the EM-2 vehicle they are essentially skipping EM-1. Is EM-2 more advanced? I thought only EM-1 used the much delayed Airbus third stage that is not human rated. Does this mean that we could revisit the issue of putting humans on the first launch?
No, they aren’t swapping the whole vehicle. They are swapping LH2 tank hardware only. Unfortunately that doesn’t make for a doom and gloom story like swapping the entire EM-2 vehicle for EM-1, so Keith may have been a little liberal with his terminology. Which is odd, given how critical he is of some NASA PAO releases.