The transfer of in-flight propellant is a key step in reaching the moon and Mars.
By early next year, SpaceX may be ready to rendezvous two Starships in orbit for an ambitious refueling test that will determine the spacecraft's potential for deep space missions.
In a recent interview with the media, Kent Chojnacki, deputy manager of NASA's manned landing system project, revealed that the in-flight propellant test of the Starship is scheduled for March 2025. The orbital demonstration is an important step for Starship and a key part of SpaceX's ability to send NASA's Artemis mission to the moon.
SpaceX signed a $53.2 million contract with NASA in 2020 to use the Starship tanker for in-orbit propellant transfers. During the third test flight, SpaceX transferred about 10 metric tons of liquid oxygen from the head tank of the Starship to the main tank in space. However, the upcoming demonstration will be much more demanding for the launch vehicle. The two Starships will be launched into low-Earth orbit about three to four weeks apart, and the spacecraft will meet and dock in orbit, with one delivering propellant to the other. After the demonstration, the two Starships will detach from each other and leave orbit.
"Once you do that, you really open up the opportunity to move large payloads and cargo beyond the reach of the Earth," Jonacki said in an interview. The in-flight propellant transfer test will end in the summer.
With aerial refueling, NASA aims to develop technology "to achieve long-term cryogenic fluid management, which is critical to establishing a sustainable presence on the moon and enabling manned missions to Mars," NASA said when it signed the contract.
As part of NASA's Artemis 3 mission, SpaceX is developing a version of the Starship to send humans to the moon in September 2026. To prepare for the lunar mission, SpaceX expects to launch 8 to 16 propellant tanker Starships into low-Earth orbit in rapid succession. Each tanker will carry about 100 to 150 tons of liquid oxygen and liquid methane and will dock with a larger fuel depot. The orbital depot will then connect with the human landing system Starship to refuel its massive 1,200-ton fuel tank. Once refueled, the Starship lander will continue its journey to the moon.
SpaceX's Starship, which is being developed for NASA's lunar missions, has been under scrutiny for making too slow progress, but the company has recently made some progress on its launch vehicle. In October, the rocket's Super Heavy 232-foot-tall (71-meter) booster gently dropped toward a special launch tower that holds the massive launch vehicle in its arms, completing its fifth test flight. Meanwhile, Starship's upper stage completed its flight with a controlled splashdown in the Indian Ocean. For Artemis, the human landing system on Starship's upper stage will need to be able to perform a precision touchdown on the lunar surface.
SpaceX has some work to do before it can launch a Starship into orbit and have it stay there, let alone get two of them into space for a tricky refueling maneuver. The company is under pressure to fulfill its contract with NASA as the space agency works to realize its Artemis dreams, and it's hard to say whether Starship will be ready for delivery by early next year.