SpaceX's Starship has accumulated at least two years of development delays since NASA picked the rocket as an astronaut moon lander in 2021, and is expected to require more time to clear remaining hurdles before landing on the moon, NASA's inspector general said Tuesday as the agency studies plans to speed up the program.
NASA has been working with an array of companies, most prominently Elon Musk's SpaceX and Jeff Bezos' Blue Origin, in its multibillion-dollar Artemis program to kickstart routine astronaut missions to the moon, pressed to do so before China sends its own crews to the lunar surface by around 2030.
But mounting delays in SpaceX's development of Starship, tapped as the program's first lander to deliver NASA astronauts to the lunar surface, have gradually pushed back what was originally a 2024 target moon landing - though officials at the time treated 2024 with skepticism.
Among the most challenging steps in Starship's path to become an astronaut-rated lunar lander, the inspector general said in its Tuesday report, is the rocket's requirement to refuel itself in space before journeying the rest of the way to the moon, a risky and delicate process that has never been attempted at such a scale.
For one Starship to land a crew of astronauts on the moon, SpaceX will first need to launch over 11 other Starships into Earth's orbit that will act as refueling tankers. One of those Starships will be a propellant storage depot requiring more than 10 Starships to fill with enough fuel that will be transferred to the moon-landing Starship.
Taller than a 15-story building, Starship is fueled by roughly 1,200 metric tons of liquid methane and liquid oxygen, two highly explosive propellants that must be kept at cryogenic temperatures, or temperatures below −238 °F (−150 °C).
Docking Starships together and carefully transferring super-cooled propellants at least 10 times in low-Earth orbit, a politically and commercially vital region of space with a soaring level of satellite traffic, would be among the riskiest challenges for a company that has routinized orbital rocket landings and astronaut launches to the International Space Station.
NASA officials overseeing SpaceX's Starship development "considers demonstrating cryogenic propellant transfer to be one of the most significant technical challenges facing" SpaceX, the report said.
"NASA is tracking a top risk that some of the cryogenic technologies and capabilities SpaceX is developing will not be adequately mature" ahead of a 2028 moon landing, the report said.
SpaceX has launched its Starship system 11 times since 2023 in a series of test flights watched closely by NASA officials.
The agency kept 2028 as its target moon landing date for Starship.
