Today was the deadline for proposals to NASA for building a Human Landing System (HLS) to take astronauts to and from the lunar surface by 2024. Blue Origin announced the outlines of its bid two weeks ago and Boeing revealed the basics of its proposal today. It relies on an upgraded version of its Space Launch System (SLS) to launch the HLS in one shot rather than the multi-launch architecture NASA envisioned. The company calls it the “Fewest Steps to the Moon” approach.

Boeing’s brief description of its proposal mirrors testimony by Doug Cooke in September to the House Science, Space, and Technology Committee. Cooke is a former NASA official who headed the agency’s Exploration Systems Mission Directorate from 2008-2011. He is now a Boeing consultant. He said NASA’s plan “doesn’t make sense to me” because it requires too many new vehicles and critical operations.

NASA’s idea is to build a small space station, Gateway, in lunar orbit as a transfer point to the Moon’s surface. It uses SLS only to launch astronauts aboard Orion spacecraft to the Gateway. There they will transfer to HLS vehicles for the trip down to and back from the lunar surface, then use Orion to return to Earth. NASA envisions three separate spacecraft for the trip down and back: a transfer vehicle to get the astronauts to a lower lunar orbit, a descent vehicle to reach the surface, and an ascent vehicle to return to Gateway. Each vehicle might need its own launch vehicle.

Cooke advocated a simpler approach using just SLS and that is what Boeing proposed today. Its plan would use a more capable version of the SLS, called Block 1B, equipped with an Exploration Upper Stage (EUS) to launch its entire HLS, which has only two instead of three stages (ascent and descent). It will be able to dock either with the Gateway or directly with Orion, obviating the need for the Gateway.

The company’s proposal calls for delivering the lander’s Ascent Element and Descent Element to lunar orbit in one rocket launch to ensure it is tailored for maximum capability and crew safety. This approach reduces the complexity and risk of sending multiple segments to orbit on multiple launches, enabling a crewed lunar surface landing with only five mission critical events instead of the 11 or more required by alternate strategies. Boeing’s integrated lander also can carry itself from lunar orbit to the surface without an additional transfer stage or “space tug,” further reducing launches and simplifying the steps to a successful landing. — Boeing

Boeing is the prime contractor for SLS and EUS. Its proposal is likely to encounter skepticism because SLS is years late and over budget and each launch is expected to be extremely expensive.

SLS has been under development since 2011. NASA originally committed to first launch in November 2018. That slipped to December 2019-June 2020, but NASA concedes June 2020 no longer is possible. At meetings of the NASA Advisory Council (NAC) last week, NASA officials said the agency has an internal planning date of the end of 2020, but the agency will not announce an actual launch date until the new head of its Human Exploration and Operations Mission Directorate (HEOMD), Doug Loverro, is on board and has a chance to review the program’s status.

SLS is composed of a core stage with four RS-25 rocket engines, two side-mounted solid rocket boosters, and, in its initial Block 1 version, an Interim Cryogenic Propulsion Stage (ICPS).

It is the core stage that is proving problematical. Officials said last week the first one will leave its manufacturing facility in Louisiana by the end of this year and go to the Stennis Space Center in Mississippi for testing. That will take until summer or fall of 2020 if all goes well. After that it will be moved to Cape Canaveral, Florida where another 6-12 months will be needed before it is ready to launch the uncrewed Artemis I test mission.

That timeline shows that it will not launch before 2021. The second SLS mission is Artemis II, a crewed test flight, that is currently expected in late 2022 or early 2023. Artemis III is the mission that will deliver astronauts to the lunar surface in 2024. SLS flights to Gateway would continue approximately once per year after that under NASA’s plan.

As for EUS, NASA suspended work on it so Boeing could focus on getting SLS ready. Its FY2020 budget proposal included no EUS funding. The Senate-passed version of the Commerce-Justice-Science appropriations bill provided $300 million anyway, but whether that will survive conference with the House is unknown.

NASA is procuring HLS through public-private partnerships similar to the commercial cargo and commercial crew programs that support the International Space Station. The companies will own and operate the systems. NASA will simply purchase services from them. The hope is that this approach will reduce cost and speed development.

Acting HEOMD head Ken Bowersox told NAC that the agency wants to pick “a minimum of three” companies to proceed with HLS designs, eventually choosing two to proceed into full development. That is how the commercial crew program was designed. NASA Administrator Jim Bridenstine insists that having multiple providers reduces risk because if one is delayed the other may not be. For commercial crew, however, both SpaceX’s Crew Dragon and Boeing’s CST-100 Starliner have encountered delays of roughly equal length so far.

As of press time, the only other bidder that has made any part of its plan public is Blue Origin. It is partnering with Lockheed Martin, Northrop Grumman and Draper Labs to build a three-part HLS along the lines NASA envisioned: a transfer vehicle (Northrop Grumman), a descent vehicle (Blue Origin) and an ascent vehicle (Lockheed Martin). Blue Origin said its proposal would “fully exploit” the capabilities of the company’s New Glenn rocket, which is under development, but other rockets also could be used.