SpaceX CEO Elon Musk details orbital refueling plans for Starship Moon lander
After a long-awaited refusal by Blue Origin’s GAO and protests by Dynetics against NASA’s decision to only award SpaceX a contract to transform Starship into a manned lunar lander, a detailed (but heavily worded) document explaining the decision was released on August 10.
In addition to ruthlessly tearing up protests from both companies, the decision by the United States Government Accountability Office also offered surprising insight into SpaceX’s HLS Starship proposal. One of those details in particular seemed to strike an irrational nerve in the online spaceflight community. Specifically, in its ruling, the GAO revealed that SpaceX came up with a mission profile that would require as much as 16 launches to fully power a Starship Lander and stage the spacecraft in an unusual lunar orbit.
After roughly 24 hours of chaos, confusion, and misplaced panic, SpaceX CEO Elon Musk finally weighed in on the GAO document’s rather surprising indication that each Starship Moon landing would require sixteen SpaceX launches.
Confirming many expectations, SpaceX’s solution to send an entire single-stage spacecraft to the Moon, land it on the lunar surface, and return it to a lunar orbit (and possibly even Earth) goes as follows .
First, SpaceX will launch a custom variant of Starship that was drafted in the GAO decision document but confirmed by NASA to be a propellant storage (or depot) ship last year. Second, once the Starship depot is in a stable orbit, SpaceX’s NASA HLS proposal would indicate that the company would begin a series of 14 oil tanker launches lasting nearly six months – each would dock at the depot and gradually fill its tanks.
Third, once the depot ship is complete, the Starship Moon lander would launch, dock with the depot, and be fully powered. Finally, the powered lander would launch its Raptor engines and head for the Moon, where it would enter an almost rectilinear halo orbit (NRHO) – a strange high-altitude elliptical orbit only necessary because NASA’s Orion spacecraft and the SLS rocket are too underpowered to reach a more normal and functional orbit around the moon.
After reaching NRHO, Starship would dock with Orion (or vice versa), receive its Artemis astronauts, land on the Moon for several days, and return to NRHO to bring those astronauts back to Orion. Once its main mission is completed, it remains to be seen whether Starship will have enough thruster to return to some sort of Earth orbit, where it could potentially be refueled and reused on future missions to the lunar surface.
Responding to GAO revealing that SpaceX has offered up to 16 launches – including 14 refuelings – spaced approximately 12 days apart for each Starship Moon lander mission, Musk says a need for “16 flights is extremely unlikely.” Instead, assuming each Starship tanker is capable of delivering a full 150 tons of payload (thruster) into orbit after a few years of design maturing, Musk thinks it’s unlikely that more than eight will be needed. tanker launches to supply the depot ship – or a total of ten launches including the depot and lander.
But, as Musk notes, as long as Starship gets closer to its design goals, that wouldn’t be a problem even if each Starship Moon lander mission somehow required 16 launches. One step closer, assuming SpaceX offered 16 launches per mission out of caution, it’s fair to assume that a 12-day gap between tanker launches is also an extremely conservative worst-case scenario. Starship design goals call for multiple reuse of ships and boosters, Musk and SpaceX say per day. Even though SpaceX is a long way from achieving these ambitious goals, Starship tankers should be able to launch every few days or maybe every week.
But thanks to SpaceX’s relatively conservative proposal, the company now knows that NASA is more than happy with Starship even though it falls about 50% below its payload performance targets and two sizes below its reusability objectives.