NASA and Rocket Lab May Figure Out In-Space Fueling Before SpaceX Does

Space is hard.

Tasks as simple as "filling up the tank" here on Earth become complex exercises in fluid dynamics when you add in factors such as:

• The extreme cold of cryogenic liquid methane and oxygen -- and its tendency to boil off as _gaseous _methane and oxygen if temperatures rise.
• The lack of gravity to move fuel in the direction you want it to go.
• The need to fire thrusters to _create _a bit of gravity.
• And the extreme temperature variations spacecraft encounter when exposed to direct sunlight (or deprived of it) while orbiting Earth with no protective atmosphere -- all while trying to steadily transfer fuel from one tank to another.

And yet, figuring out how to refuel spacecraft in orbit will be essential if we're ever to launch spacecraft capable of traveling more than just "one tankful" away from Earth. It's especially essential in the context of NASA's Project Artemis, which proposes to use a SpaceX Starship, tweaked to serve as a Human Landing System, to carry astronauts to the moon and back.

Image source: Getty Images.

The problem

SpaceX estimates it will need to launch 12 Starships, each fully loaded with methalox fuel (liquid methane and liquid oxygen), to fill up its Human Landing System in orbit. This will give HLS enough fuel to leave Earth orbit, travel to lunar orbit, dock with the Artemis IV Orion spacecraft, descend to the moon, and finally reascend to lunar orbit for another docking with Orion. Before this can happen, though, SpaceX must master the procedure for transferring cryogenic liquid fuel between Starships in orbit, first by demonstrating that it is feasible, then by repeating it -- over and over and over again.

At last report, SpaceX was planning to demonstrate orbital cryogenic fuel transfer between Starship tankers in June 2026. Starship is a bit behind schedule in its development, however, and there's no guarantee it will accomplish this (which would require back-to-back Starship launches, by the way, probably no more than a week apart) next month.

But hopefully soon.

Meanwhile, at Rocket Lab

Meanwhile, NASA just announced plans to conduct its own cryogenic fuel transfer demonstration -- SpaceX not included.

As reported on NASA.gov last week, Rocket Lab (RKLB +8.23%) has been hired to launch an Eta Space-built LOXSAT spacecraft on a nine-month mission to demonstrate "11 cryogenic fluid management technologies" in orbit, "including reducing boiloff, transferring propellant, maintaining tank pressure, and gauging propellant levels." All of these will be "necessary for creating in-space propellant depots, essentially gas stations in space, that could support long-term exploration."

They'll also be essential for refueling Starships in orbit.

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What it means for Rocket Lab

Eta is a start-up space company -- so new that S&P Global Market Intelligence doesn't yet have any data on it. Rocket Lab's role in the project is to provide the Electron rocket to launch LOXSAT and a Photon satellite bus to carry the payload to the correct orbit for the demonstration. A tentative launch date for LOXSAT has been set for July 17.

Now it's a race between SpaceX and Rocket Lab to see which company can first demonstrate a technology that may be essential to the future of SpaceX itself.