NASA demonstrates how SpaceX refuels spacecraft in low Earth orbit

Sometime next year, NASA believes SpaceX will be ready to attach two Starships into orbit for an ambitious refueling demonstration, a technical feat that would bring the moon within reach.

SpaceX has entered into a contract with NASA to supply two human-rated Starships for the first two astronaut landings on the Moon through the agency's Artemis program, which aims to return humans to the surface of the Moon for the first time since 1972. The first of these landings, on the Artemis III mission NASA, currently targeted for 2026, although this is widely viewed as an ambitious timeline.

Last year, NASA awarded a contract to Blue Origin to develop its own Blue Moon lunar lander for humans, giving Artemis managers two options for follow-on missions.

The designers of both probes were forward-thinking. They designed the spacecraft and the Blue Moon to refuel in space. This means it could eventually be reused for multiple missions and, ultimately, could make use of propellants produced from resources found on the Moon or Mars.

Amit Kshatriya, who leads the Moon to Mars program within NASA's Exploration Division, explained SpaceX's plan to do this in a meeting with a committee of NASA's advisory board on Friday. The Starship test program is gaining momentum, and the next test flight is expected to be from SpaceX's Starbase launch site in south Texas by the end of May, he said.

“Production is not the problem,” Kshatriya said. “They extract the cores. The engines flow into the factory. That's not the problem. The problem is that doing what they're trying to do is a huge development challenge… We have to overcome that.” This propellant transfer problem is the right one to try and solve. We are trying to build a blueprint for deep space exploration.

Refueling route map

Before reaching the moon, SpaceX and Blue Origin must master the techniques and technologies needed to refuel in space. Currently, SpaceX is scheduled to attempt the first practical demonstration of transferring propellant on a large scale between two Starships in orbit next year.

There will be at least several more Starship test flights before then. During the last Starship test flight in March, SpaceX tested transferring cryogenic propellant between two tanks inside the vehicle. Transferring liquid oxygen from tank to tank was part of a demonstration supported by NASA funding. This demonstration will allow engineers to learn more about how fluid behaves in a low-gravity environment, agency officials said.

Kshatriya said that while engineers are still analyzing the results of the cryogenic transport experiment, the test on the Mars Starship flight “was successful by all standards.”

“This achievement is behind them,” he said on Friday. Now, SpaceX will launch more Starship test flights. The next launch will attempt to verify some additional capabilities that SpaceX did not demonstrate in the test flight in March.

This will include a precision landing of Starship's Super Heavy booster in the Gulf of Mexico, which is necessary before SpaceX attempts to return the booster to the launch pad in Texas. Another goal would likely be to restart a single Raptor engine aboard the Starship during flight, which SpaceX did not achieve on the March flight due to unpredictable rotation rates on the vehicle as it rocketed through space. Achieving an in-orbit engine restart — which is necessary to guide the spacecraft toward controlled reentry — is a prerequisite for future launches into a stable higher orbit, where the ship can hang around for hours, days or weeks to deploy satellites and attempt refueling.

In the long term, SpaceX wants to increase Starship's launch cadence to several daily flights from multiple launch sites. To achieve this goal, SpaceX plans to quickly recover and reuse Starships and Super Heavy boosters, building on experience from the partially reusable Falcon 9 rocket. Elon Musk, founder and CEO of SpaceX, is keen to get the ships and boosters back into use as quickly as possible. Earlier this month, Musk said he was optimistic SpaceX could recover the Super Heavy booster in Texas later this year and land the Starship vehicle again in Texas sometime next year.