Alongside last week’s Trump Administration budget proposal to cancel future Space Launch System (SLS) upgrades, NASA Administrator Jim Bridenstine announced additional changes are being considered which would overhaul the early manifest of Exploration flights. The Administration’s new budget proposes defunding the Exploration Upper Stage (EUS) and related projects beginning with Fiscal Year 2020 that starts on October 1.



In subsequent Senate testimony, Administrator Bridenstine confirmed that SLS would not be able to meet the agency’s previous June, 2020, launch date commitment for Exploration Mission-1 (EM-1) and that NASA had started a study to look at commercial launch options to try to save the schedule. The Administrator also described additional mission changes that are under consideration in a message to the agency workforce following the announcement of the latest EM-1 study.

Under the new proposals, the next two Exploration missions for NASA’s Orion crewed spacecraft would be replaced by three missions to get back on schedule. In addition to the commercially launched EM-1, the other new missions would introduce a new lunar payload and skip the test flight for the first crewed mission in favor of an operational Orion mission to fly to the new payload.

Mothballs proposed for EUS historically mean cancellation

The President’s Fiscal Year 2020 (FY 2020) Budget Request proposes mothballing efforts to build the Exploration Upper Stage (EUS), a larger, higher-performance stage still under development. Work to stand up a supply chain and begin manufacturing stage hardware was suspended last year following an agreement in the FY 2018 budget to build a second Mobile Launcher (ML) for the EUS-based configuration of SLS, called Block 1B.

The green light and funding for the second ML (ML-2) in late March of last year allowed NASA’s Exploration Systems Development (ESD) division to use the first ML (now called ML-1) for additional launches of the Block 1 configuration. Last year’s suspension of work to begin prepare manufacturing facilities, start up a supply chain, and conduct a Critical Design Review (CDR) for EUS was an additional result, with NASA and prime contractor Boeing looking at design changes to increase its performance for lunar payloads.

The President’s FY 2020 budget request proposes defunding EUS, Block 1B, and related projects like ML-2. The FY 2020 request calls for all Lunar Gateway payloads previously under consideration to fly “co-manifested” on SLS with Orion in the Block 1B Crew configuration to now use commercial launch services.

“We won’t need co-manifesting for the Gateway,” Andrew Hunter, NASA’s Deputy Chief Financial Officer, said in a teleconference during the budget proposal’s rollout on March 11. “We won’t need EUS for a while.”

“We will eventually need EUS, but we don’t have a precise date for exactly when or which mission that will be at this point,” Brian Dewhurst, Senior Budget Analyst for NASA, added.

After ML-2 was purchased, a subsequent ESD directive similarly noted conversion work on ML-1 was deferred and would only be done if required and if funds to do so became available. With the Administration saying they see no known requirements for EUS nor any timetable for future funding, it is likely that the indefinite, multi-year defunding they propose for EUS would be permanent.

Similarly, related projects like ML-2 would be defunded beginning in FY 2020. “Although NASA began design and construction on the second mobile launcher platform, additional funding to complete the project is being deferred. NASA does not have plans to utilize the second mobile launcher in the near term,” NASA’s FY 2020 request submission notes.

ML-2 was officially started a year ago by Congress; however, the Administration did not request it. The President’s FY 2020 budget request reaffirms the Administration’s opposition to a second Mobile Launcher.

Past NASA human exploration programs such as Apollo, the Space Shuttle, and Space Station Freedom saw similar cutbacks to extended production, additional capabilities, future upgrades, or broadly scoped early designs, where initial defunding turned out not long after to be permanent descoping, as past NASA Administrations looked to fund other priorities or cover top-line agency cuts.

The Administration request proposes cutting the SLS budget by 18 percent from FY 2019 and the EGS budget by 32 percent.

EM-1 commercial launcher study to protect schedule

On March 13 NASA Administrator Jim Bridenstine appeared before the Senate Commerce, Science, and Transportation Committee as a witness in a public hearing. Following opening statements, Senator Roger Wicker of Mississippi, Chairman of the Committee, opened questioning by noting that “last week NASA informed Congress of yet another delay in EM-1. NASA had planned to launch no later than June of 2020; however, NASA now says that further delays are anticipated.”

“SLS is struggling to meet its schedule,” Bridenstine said in response, then announcing an internal agency study was already underway to use commercial launch services as a replacement to hold the EM-1 mission to its June, 2020 schedule commitment.

At the completion of Key Decision Point-C (KDP-C) for the program in August, 2014, the SLS readiness date for the first launch was projected to be no later than November, 2018, although the agency said it was working to an earlier date. Following reviews during 2017 of the status of all three Exploration Systems Development (ESD) programs — Exploration Ground Systems (EGS), Orion, and SLS — in November, 2017, the readiness date was projected to be June, 2020.

The critical path to the first launch for SLS is its new piece, the Core Stage. NASA’s Office of Inspector General detailed cost and schedule overruns for the SLS Core Stage and the reasons behind them in a report published in October.

In announcing the delay, Administrator Bridenstine also spoke about a commercial launch alternative to hold the EM-1 schedule. “Certainly, there are opportunities to utilize commercial capabilities to put the Orion crew capsule and the European Service Module in orbit around the Moon by June of 2020, which was our originally stated objective, and I have tasked the agency to look into how we might accomplish that objective,” he said in his Senate testimony.

The Administrator spoke about one possible alternate mission profile during the March 13 Senate hearing, which would be a two-launch, Earth Orbit Rendezvous (EOR) mission similar to ones considered during the Constellation Program that was cancelled in 2010.

“Here’s what we can do potentially — we’re starting that [study] process now. We could use two heavy-lift rockets to put the Orion crew capsule and the European Service Module in orbit around the Earth, launch a second heavy-lift rocket to put an upper stage in orbit around the Earth and then dock those two together to throw around the Moon the Orion crew capsule with the European Service Module,” he explained.

“I want to be clear we do not have right now an ability to dock the Orion capsule with anything in orbit, so between now and June of 2020, we would have to make that a reality,” Bridenstine noted. Orion is not scheduled to incorporate Rendezvous, Proximity Operations, and Docking (RPOD) capabilities until Exploration Mission-3.

“There are options to achieve the objective but it might require some help from the Congress,” he added, referring to the appropriation of additional funding. For an EOR mission Orion would require completing development, integration, and testing of RPOD hardware and software, while a docking kit would need to be added to the upper stage.

Given the emphasis in the Senate hearing on responding to EM-1 launch delays, the lack of discussion about Orion’s status suggests the Administration believes it can support June, 2020 launch readiness, although this doesn’t likely include the additional RPOD integration work.

The EM-1 Orion Crew and Service Modules are going through standalone testing in the Operations and Checkout (O&C) Building at the Kennedy Space Center (KSC) in preparation for their final mating planned in the Spring.

The mated Orion was scheduled to be to be transported to Plum Brook Station in the Summer for a few months of thermal vacuum and electromagnetic interference/compatibility testing, followed by return to KSC for final installations and closeouts before it is ready for launch preparations.

It is unclear at this point how the hardware and software development work for RPOD would be integrated with the mated spacecraft’s testing schedule; NASA officials had previously indicated most of the contingency time had been removed.



The currently baselined EM-1 mission would launch an uncrewed Orion spacecraft on a trans-lunar injection (TLI) trajectory; once released from the launch vehicle, it will fly solo for the first time. The Orion would then make two large engine burns to insert itself into a Distant Retrograde Orbit (DRO) around the Moon.

Depending on the time of year, Orion would stay in the DRO for a half or one and a half orbits before making two more large engine burns to return to Earth. Preliminary analysis indicates a June, 2020, launch of the full-up mission would fall into the “long-class” category, with Orion staying in a DRO with a twelve-day long period for one and a half laps and flying a five-week long flight.

Prior to Administrator Bridenstine’s announcement of the alternate launch study for EM-1, notes passed to L2 indicated that NASA Human Exploration and Operations Mission Directorate (HEOMD) Associate Administrator Bill Gerstenmaier had sent out a memo in early March indicating that studies to look at ways to keep the EM-1 launch in 2020 could not compromise any of the mission objectives; besides that, everything else was on the table.

The highest priority objective of the EM-1 mission is a lunar-velocity reentry test of the redesigned Orion heatshield, along with a full end-to-end test of the re-entry sequence and an in-space demonstration of Orion systems, many of which are flying for the first time.

Although Bridenstine’s public comments stressed flying EM-1 as a lunar orbit mission, there has been speculation that launching Orion out to near lunar distance without attempting either a lunar orbit or a lunar flyby could meet the highest priority objectives. Dropping the lunar orbit requirement or lunar flyby options would also relax launch opportunity constraints created by flying to the Moon and could perhaps reduce launch vehicle performance requirements enough to drop the EOR proposal and RPOD development work.

Manifest overhaul considerations to get back on schedule

On March 14, Bridenstine described a reworking of the rest of the short-term Exploration manifest being considered in the wake of the new EM-1 study. “Our goal would be to test Orion in lunar orbit in 2020 and free up the first SLS for the launch of habitation or other hardware in 2021,” he wrote in a message to the workforce that was also published by the agency. “This would get us back on schedule for a crewed lunar orbital mission in 2022 with the added bonus of a lunar destination for our astronauts.”

Based on the hypothetical of the EM-1 Orion launch removed from SLS, flying “habitation or other hardware” in 2021 on the launch vehicle’s first flight is a new mission to analyze and prepare for in addition to the definition and procurement of a lunar-orbiting habitat. SLS would be flying in a different configuration without Orion, similar to that proposed for flying Europa Clipper directly to Jupiter.

A cargo-configured SLS vehicle for the first launch could also impact the ML-1 configuration for the new mission, with Orion-related swing arms at the top of the umbilical tower that might need to be locked down and disabled in ground software under development. The Interim Cryogenic Propulsion Stage (ICPS) upper stage for the first launch, which is ready and waiting in storage at KSC, may also be an option for use as a part of the EM-1 commercial launcher study; if that were also removed from the first SLS launch, production of downstream ICPS units would need to be adjusted to deliver them sooner.

A lunar habitation module that would be ready for launch on SLS as a primary payload in 2021 is a new proposal. Launch of the Power Propulsion Element (PPE), currently the first Gateway module to be commercially demonstrated, was delayed by the recent partial government shutdown to no later than December 31, 2022. PPE awards are expected in a few months.

A cargo configuration of SLS Block 1 would have a similar twenty-seven metric tons of performance to TLI as the crew configuration that launches Orion, but integration of the new payload and full trajectory profile needed for this new proposal along with other changes to the first SLS launch plan would need to be analyzed. A standalone payload would also need to integrate or manifest PPE/space tug-like navigation and maneuvering capabilities.

The third mission in the sequence, calling for Orion orbiting the Moon in 2022 and destined for the new, bonus Lunar payload, is also significantly different from the proposed initial crewed test flight that NASA had previously baselined.

Instead of a lunar flyby test flight for the first crew to fly on Orion, the combination lunar orbit / lunar destination mission described is closer to outlines for the operational Exploration Mission-3 flight to dock to the Gateway. EM-2 as planned included risk reduction aspects to its profile, beginning with orbits that stayed near Earth to shorten a return trip early in the flight if necessary before making a swing around the Moon and returning.

Early outlines for EM-3 used the EUS to carry Orion and a Gateway payload to dock to the PPE. This new proposal for flight in 2022 skips the EM-2 test flight and flies the EM-3 profile as an Orion-only SLS Block 1 mission. Moving the EM-3 flight profile up to fly in the EM-2 slot could take advantage of the proposed acceleration of development and integration of rendezvous, proximity operations, and docking (RPOD) capabilities for Orion in the newly proposed EM-1.

It is unknown where in lunar orbit the lunar habitation payload referred to in Administrator Bridenstine’s workforce message would be located, whether it would be similar to the Gateway’s lunar near-rectilinear halo orbit (NRHO) or a different one, but the timeline in the Administrator’s message places the cargo launch and probably the Orion crew mission to it prior to the scheduled launch of the PPE.

Assuming the PPE launches on schedule at the very end of 2022 and a one-year long demonstration by the commercial provider, NASA would accept transfer of ownership of the PPE in late 2023. If an Orion rendezvous and docking mission were flown during the demonstration period, PPE requirements still indicate demonstrating use of Solar Electric Propulsion (SEP) on a long transfer from its initial trajectory at launch vehicle separation to insertion into the planned lunar halo orbit.