NASA moves to procure a second crewed lunar lander

An artist’s rendition of an astronaut descending the ladder on a lunar lander. Credit: NASA

SEP. 17, 2022—Yesterday, NASA published a request for proposals for its Sustaining Lunar Development contract under the Human Landing System program. The contract is effectively NASA’s request for a new lunar lander to be developed concurrently with SpaceX’s already selected Starship HLS, with a crewed test flight targeted for no later than 2028, within the notional timeframe of the Artemis V mission. In addition, the contract also aims to procure a “Human-class Delivery Lander” for transporting cargo specifically for crewed lunar missions.

The contract, formally known as NextSTEP-2 Appendix P: HLS Sustaining Lunar Development, comes as the Artemis program awaits the launch of its first major mission, Artemis I, but also during a time of significant reconfiguration and re-baselining for the program. The Appendix P contract is but one piece in a large puzzle for NASA’s efforts to procure a lunar lander, which has proved to be convoluted for the agency due to shifting timelines and funding levels. 

A flowchart of the procurement path for NASA’s Human Landing System program. Credit: NASA

While Appendix P (SLD) follows the agency’s pre-Artemis 2028 landing timeline, Appendix H, which was awarded to SpaceX, was designed to meet the 2024 landing deadline declared by former Vice President and then-chair of the National Space Council Mike Pence on March 26, 2019. However, congressional support for HLS funding under Appendix H came up short, with the program receiving just 20% of its requested budget. This resulted in the selection of a single lander—the SpaceX Starship HLS, rather than the two initially expected for dissimilar redundancy. 

Growing concerns from government oversight offices such as NASA’s Office of Inspector General and the US Government Accountability Office over the Starship HLS’s timeline have also highlighted the need for a 2nd lander as requested under Appendix P. In a report dated November 15, 2021, from NASA OIG, titled “NASA’s Management of the Artemis Missions”, the Inspector General declared that the Starship HLS schedule is “unrealistic and not supported by recent schedule risk analysis.” That lander is currently targeting a first crewed flight in 2025 as part of the Artemis III mission. However, based on historical precedent for previous NASA programs, the OIG is expecting a landing closer to 2028, identical to the goal of the SLD / Appendix P lander for which proposals are now open.

A chart showing historical delays for recent NASA programs in comparison to the schedule for Starship HLS, the NextSTEP-2 Appendix H lander, as of November 2021. Source: NASA OIG

With the case for a second lander stronger than ever, the Sustaining Lunar Development contract aims to also ensure that the lander procured under Appendix P is—as the name suggests—able to fly multiple missions to the Moon sustainably in a similar way to today’s Commercial Crew and Cargo vehicles. The Starship HLS is also under consideration for sustainable flights, but separately under Appendix H Option B, which would add a second crewed demonstration flight for a version of Starship HLS that meets the same requirements as the Appendix P lander. SpaceX is not eligible to bid for Appendix P.

The requirements for the sustainable lander are designed around long-duration stays at a future Artemis Base Camp, in contrast to the Appendix H contract’s requirements being significantly more oriented towards meeting the now-defunct 2024 deadline. At the high level, the crewed lander must be capable of completing two Design Reference Missions: the first being a six-day sortie and the second being a 33-day lunar base stay.

A conceptual render of the Artemis Base Camp. Credit: NASA

For the six-day mission, the lander must be able to carry two astronauts and one ton of cargo to the lunar surface. The lander also must be capable of supporting five EVAs (four planned, one unplanned) and then return half a ton of cargo to Gateway.

For the 33-day base mission, the lander must be able to carry a crew of four to the lunar surface. The crew would then transfer out of the lander to a surface habitat, with the lander required to be able to survive at least 30 days on the surface uninhabited, including at least 10 days of lunar night. It must also be able to carry at least 1,780 kg to the surface, and 740 kg back.

For both mission sets, the lander has to also be capable of conducting a mission either autonomously or manually at any point, and it must be able to abort at any point in the mission. The lander also has a set of imaging requirements, with still imagery having the goal of “matching or exceeding the imagery provided by the Apollo missions.” Live video transmitted from the landers must be at least full HD at 30 Hz and preferably 4K at 60 Hz and will run even while the lander is uninhabited. Furthermore, the lander should be able to leave a camera on the lunar surface to stream the ascent.

The human-class cargo lander has similar requirements and must be able to carry at least 12 tons to the lunar surface. The cargo lander must be able to carry both integrated cargo (i.e., permanently on the lander) and offloaded cargo. The lander is expected to complete its mission entirely by itself, with the provider free to take any approach to staging, multiple launches, or aggregation.

Proposals for Appendix P must be submitted by November 15. There is a 5-year period of performance for the contract, culminating in one uncrewed and one crewed demonstration mission for the lander. The lander must successfully demonstrate an end-to-end crewed mission to the lunar South Pole staged from the Lunar Gateway station. NASA expects to award a single, firm-fixed price contract, but reserves the ability to select multiple or none as well.

Importantly, Appendix P is a development contract and does not award any post-certification missions. Successful baseline designs from Appendix P, as well as SpaceX’s Starship under Appendix H Option B, will be allowed to bid for the Sustaining Lunar Transport contract, which is the operational contract under the NextSTEP-2 / Human Landing System program that does award post-certification crew and cargo contracts. That contract has yet to be issued.

Dynetics’ revised lunar lander design for Sustaining Lunar Development under Appendix N. Credit: Dynetics

So far, several industry companies have expressed interest in the Sustaining Lunar Development contract. Blue Origin, Dynetics, Lockheed Martin, Northrop Grumman, and SpaceX all won awards under Appendix N, which consisted of precursor risk-reduction studies for SLD. It is unknown whether Blue, Lockheed, and Northrop still intend to bid as one under the National Team formed with Draper for their Appendix H bid, or if the companies will bid separately. 

While the contract targets a first flight in 2028, realistically, the time frame in which the Appendix P lander—or any crewed lander at all—will actually fly is up in the air. NASA does not yet have an updated schedule for Artemis II, nor does it have a complete schedule for Artemis III, the former of which is already experiencing significant knock-on effects from Artemis I delays and will likely be pushed to early 2025 without significant corrective actions by NASA. 

A chart showing the effect of Artemis I’s delays on Artemis II and III, as well as the theoretical minimum time needed between missions according to NASA. Credit: U.S. GAO

Furthermore, officials at NASA’s Advanced Exploration Systems put completing the schedule for Artemis III on hold during Blue Origin’s protest and U.S. Federal Court complaint for the Appendix H sole-source award, and now expect to complete the schedule within the coming weeks. As a result of this, the current 2025 date for Artemis III’s landing attempt does not account for months, possibly years of delays not only due to Blue Origin’s protest, but also due to Artemis II’s schedule shifting significantly as well as technical delays due to the sheer complexity of the Starship HLS system.

In the context of these delays, the Appendix P contract can be seen as a return to the pre-2019 Gateway-first architecture that aimed to return to the Moon in 2028 under the goals of 2017’s Space Policy Directive-1. Exploration Systems Development officials had already raised the possibility of using Artemis III as another crewed flyby or Gateway mission as early as November 2021, due to the looming expectation of significant delays with Starship HLS. 

SpaceX’s Ship 24 and Booster 7 at the Starbase launch site in Boca Chica, TX. While SpaceX has conducted significant testing at the launchpad of the integrated Starship system, the company has yet to test any of the specialized variants required for the Appendix H HLS. Credit: SpaceX

So far, ESD and OIG officials’ concerns have been largely valid. To meet the current schedule, Starship would have to complete an end-to-end uncrewed landing demonstration by mid-2024, which would include several orbital refueling missions in rapid succession, a prototype HLS capable of landing on the lunar surface, and the launch vehicle and ground infrastructure to enable the mission. However, 20 months away from the demonstration, SpaceX has yet to fly its barebones Starship orbital test flight and the company has made little to no visible progress on an HLS prototype ship, or the infrastructure required to fly several tanker ships to refuel on-orbit, or an orbital refueling demo at all, critical for an HLS mission.

While understandably disappointing, these delays should have been completely expected from the moment Appendix H, best described as a “boots on the moon ASAP” contract, was funded at nearly five times less than its request before contract award. In returning to the original 2028 timeline, whether intentionally so or not, the Artemis program’s schedule now better accommodates the flat funding profile expected from the beginning. Critically, Appendix P is a big move for NASA to secure a plan B for the Artemis program’s most important goals this decade: to land a woman and person of color of the Moon, and to begin a sustainable lunar exploration program.


Article written and edited by Lavie Ohana.

Glossary of terms:

NextSTEP-2 – Next Space Technologies For Exploration Partnerships

  • Appendix E – Human Landing System Risk Reduction
  • Appendix H – Human Landing System (Starship HLS)
  • Appendix H Option B – Evolution from Initial to Sustaining HLS (Starship HLS/SpaceX)
  • Appendix N – Sustainable Lander Studies and Risk Reduction 
  • Appendix P – Sustaining Lunar Development – SLD – (Currently accepting proposals)

ESD – NASA’s Exploration Systems Development Mission Directorate
GAO – Government Accountability Office
HLS – Human Landing System
NRHO – Near Rectilinear Halo Orbit (Gateway orbit)
OIG – (NASA) Office of Inspector General
Sustaining Lunar Transport – SLT (Post-certification missions)

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