The SLS Saga: 2018 Mid-Year Project Update
In this SLS Project Update, we will explore the good news on the mobile launcher front, improvements in Block 1's capabilities, and troubles for the Exploration Upper Stage. For additional posts, please visit the SLS Saga Overview microsite here.
Second Mobile Launcher
Earlier this year, the SLS Project got a pleasant surprise from the 2018 omnibus spending bill in the form of “[$350 million] for a second mobile launch platform.” This is great news for the SLS Program since it should increase the project’s mission tempo by eliminating a 33-month stand-down period that was need to retrofit and redesign the first mobile launch to support changes in launch structure from a Block 1 configuration to a Block 1B configuration. The second launcher will also bring the SLS Program more in-line with the Apollo Program when three Mobile Launchers were constructed to support various Saturn V rocket launches.
According to NASA’s solicitation for the second mobile launcher, it will conduct a two-phase procurement process for the design and construction of Mobile Launcher 2 (“ML2”). In Phase 1, submissions to a Request for Qualifications will be used to determine the 5 best offerors to compete in Phase 2. In Phase 2, NASA will award the contract to one of these five contractors that will offer “the best value to NASA” via an analysis of their answers to the Request for Proposals. NASA’s solicitation indicates that the design and construction of ML2 should take no more than 44-months, or a little bit over 3.5 years. Therefore, if this process were to begin by year-end, ML2 is anticipated to be ready for operations by no earlier than third quarter of 2022.
While the first mobile launch is designed to launch SLS’s Block 1 configuration (which uses an Interim Cryogenic Propulsion Stage (“ICPS”) as its upper stage), ML2 will be built and configured for the Exploration Upper Stage (“EUS”), the more powerful upper stage that forms the centerpiece of the Block 1B Configuration and will be a permanent long-term feature of the SLS rocket. Therefore, while ML2 has been revived by Congressional funding, its fate is still indispensably tied to the fate of the EUS.
Delays Ahead: Exploration Upper Stage
Speaking of the EUS, recent statements by NASA suggest that it will take at least four or five more years before this upper stage is fully designed and developed. Although NASA also received $300 million for the development of EUS in the latest budget, many uncertainties remain. Currently, NASA is trying to lower the expenses related to EUS by seeking out "low cost alternate engines that meet stage interfaces and launch vehicle performance requirements." Additionally, new solicitations this year related to the EUS suggest that the design is not quite off the drawing boards yet.
With many of the Exploration Missions dependent on the increased launch capability that the EUS will bring, any delays in construction of this component could jeopardize the future of the SLS Program as a whole.
Updates to Block 1’s Capabilities
Although EUS's fate is uncertain, there is a bit of good news for other specifications of the SLS rocket in the form of increased payload capabilities for the Block 1 configuration. According to Spaceflight Insider’s discussions with NASA, the latest analysis indicate that “Block 1 configuration of SLS can deliver an estimate mass of 95 metric tons (209,439 pounds) to low-Earth orbit . . . .” This is an increase of 25 metric tons over previous estimates.
This increased launch capability means that instead of just having Exploration Mission One launch on the Block 1 Configuration, the first set of planned Exploration Missions can all be launched on this same configuration. With room in the budget for an additional mobile launcher, this allows the SLS program to work on its short-term goals and long-term vision at the same time: having demonstrable results through the ICPS-based Block 1 configuration while creating the momentum to continue the development of EUS-based block configurations.
However, advocates of SLS should not rest on their laurels and use the success of Block 1 as justification for the SLS Program. Although Block 1 can now deliver 95 metric tons to low earth orbit, each launch is estimated to cost $1.5 billion to $2.5 billion. Whereas commercial competitors such as SpaceX’s Falcon Heavy can launch 63.8 metric tons to low earth orbit at only $90 million per launch, less than one-tenth of the SLS launch costs. Not only will this limit the SLS’s market (the U.S. Air Force has already signed a contract with SpaceX for a ride on the Falcon Heavy), SLS critics can also point to these facts as reasons why NASA should leave the rocket-building business to its commercial counterparts. Hence, while the improved capabilities of Block 1 brought some time for the SLS Program, if NASA does not show significant continued progress for its rocket, NASA risks being left behind in the launch dust of its commercial competitors.
- Omibus Spending Bill of 2018 (Consolidated Appropriations Act, 2018): http://docs.house.gov/billsthisweek/20180319/BILLS-115SAHR1625-RCP115-66.pdf
- Solicitation for Mobile Launcher 2: https://www.fbo.gov/index?s=opportunity&mode=form&id=a5b64582226168e57c244d906a13d10a&tab=core&_cview=
- Mobile Launcher 2 Procurement Information: https://procurement.ksc.nasa.gov/ml2
- Solicitation for SLS Stages Production and Evolution: https://www.fbo.gov/index.php?s=opportunity&mode=form&id=f4651ac4ba2e9841c226cca34050a43d&tab=core&tabmode=list&=
- Revised RFI related to the Exploration Upper Stage: https://www.fbo.gov/index?s=opportunity&mode=form&tab=core&id=4599556849e76bc3d5f4bc8b43b2276e&_cview=0