NASA this month successfully completed the exploration upper stage (EUS) preliminary design review (PDR) for its Space Launch System (SLS) rocket, according to an agency statement.
The PDR kicked off Nov. 30 with approximately 500 experts from across NASA and industry assessing more than 320 items on the EUS, including documents and data. The PDR board was completed Jan. 19 with the board voting unanimously that the EUS is ready to move to the critical design review (CDR) phase. CDR, the next major programmatic milestone that will provide a final look at the design and development of the EUS before beginning full-scale fabrication, is scheduled to take place in fall 2018, according to NASA spokeswoman Cheryl Warner. Component, material and tooling development for EUS will now begin, according to Kent Chojnacki, EUS team lead and PDR manager.
The first crewed flight of SLS and its Orion spacecraft is tentatively scheduled for 2021. Starting with this first crewed mission, future configurations of SLS will include the larger EUS and use four RL10C-3 engines. The EUS will replace the interim cryogenic propulsion stage that will be sued on the initial configuration of SLS for the first uncrewed flight test with Orion.
The EUS will use a 8.4-meter diameter liquid hydrogen tank and a 5.5-meter diameter liquid oxygen tank. A new universal stage adapter will connect the EUS to Orion and will be capable of carrying large co-manifested payloads, such as a habitat.
Once built, the EUS structural test article will undergo qualification testing at NASA Marshall Space Flight Center, Ala., to ensure the hardware can withstand the stresses of launch. “Green run” testing on the first flight article will be done at NASA Stennis Space Center, Miss. For the test, the EUS and RL10 engines will fire together for the first time before being sent to Kennedy Space Center, Fla., for the tentative 2021 launch.
SLS is developed by Boeing [BA], Orion is developed by Lockheed Martin [LMT] while the RL10 is developed by Aerojet Rocketdyne [AJRD].
In other SLS news, a pair of lawmakers last week introduced a bill in their respective legislative chambers that would require NASA to use SLS and Orion as part of an effort to expand permanent human presence beyond low earth orbit (LEO) and establish a human presence on Mars. The bill, introduced by Rep. John Culberson (R-Texas) and Sen. John Cornyn (R-Texas), would require the NASA administrator to develop a range of mission architectures and approaches utilizing SLS and Orion.