SLS Upper Stage Changes While Software Problems Linger

Statement by Acting NASA Administrator Robert Lightfoot - Hearing on NASA FY2019 Budget

"NASA plans to launch an initial, uncrewed deep space mission, Exploration Mission-1 (EM-1), in FY 2020. The mission will combine the new heavy-lift SLS with an uncrewed version of the Orion spacecraft on a mission to lunar orbit. A crewed mission, EM-2, will follow in 2023. The FY 2019 budget fully funds the Agency baseline commitment schedule for EM-2 and the Orion spacecraft and enables NASA to begin work on post EM-2 missions. Missions launched on the SLS in the 2020s will establish the capability to operate safely and productively in deep space."

FY 2019 Budget Hearing - National Aeronautics and Space Administration (Video of hearing)

NASA may fly crew into deep space sooner, but there's a price, Ars Technica

"NASA will likely launch its first astronauts into deep space since the Apollo program on a less powerful version of its Space Launch System rocket than originally planned. Although it has not been officially announced, in recent weeks mission planners at the space agency have begun designing "Exploration Mission 2" to be launched on the Block 1 version of the SLS rocket, which has the capability to lift 70 tons to low Earth orbit. Acting agency administrator Robert Lightfoot confirmed during a Congressional hearing on Thursday that NASA is seriously considering launching humans to the Moon on the Block 1 SLS. "We'll change the mission profile if we fly humans and we use the Interim Cryogenic Propulsion Stage (ICPS), because we can't do what we could do if we have the Exploration Upper Stage," Lightfoot said."

Keith's note: Note that there is no mention of this substantial internal activity in Lightfoot's prepared statement at the hearing. One has to assuem that they would have rather not talked about this if at all possible. In addition to all of the excellent points raised in this article there is another looming factor that will affect this decision. Readers of NASAWatch will recall that there has been a lot of chaos at NASA MSFC in the safety group that is certifying the SLS flight software. One of the things that scared this team the most was the sad state of current software and what would have to be done to human rate SLS - with the Exploration Upper Stage (EUS) on EM-2. Sources report that the internal consensus was that the software would have to be started from a clean slate in order to human rate the SLS.

But, not only was NASA planning to launch humans on SLS for the first time on EM-2, they were going to launch them for the first time on a launch vehicle configuration that had never flown before (SLS + EUS i.e. Block 1B Crew). The last time NASA did this was STS-1. If this expanded use of Interim Cryogenic Propulsion Stage (ICPS) is going to become the new baseline, sources report that the task of human rating it will be simplified since they can start much earlier. And, when humans do fly on it there will be at least one full-up flight of the SLS+ICPS SLS Block 1 configuration (EM-1) under their belt.

That said, the SLS software safety issue is still a mess - as will soon be revealed in internal and external reports on this situation.

- SLS Software Problems Continue at MSFC, earlier post
- This Is How NASA Covers Up SLS Software Safety Issues (Update), earlier post
- MSFC To Safety Contractor: Just Ignore Those SLS Software Issues, earlier post
- SLS Flight Software Safety Issues Continue at MSFC, earlier post
- SLS Flight Software Safety Issues at MSFC (Update), earlier post
- Previous SLS postings

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