Colorado-based Sierra Space has successfully completed a test campaign of its new liquid oxygen and liquid hydrogen-fuelled upper stage engine at a US Air Force Base in California.
Research Laboratory (AFRL) was aimed at continuing to mature upper stage engines to fulfil future National Security Space Launch (NSSL) missions.
NSSL missions are intended to assure the US Department of Defence (DOD) access to space. The US Air Force has been in the process of selecting its next generation NSSL vehicles since 2018.
VR35K-A uses a fuel-rich staged combustion cycle, turbopump architecture and Sierra Space’s patented VORTEX combustion chamber technology to produce 35,000 lbf of thrust.
The Californian test programme followed a similar campaign in 2024 at the company’s Badger Propulsion Test Facility in Wisconsin, where it says it showed stable, efficient thrust operation.
“We are delivering high performance, reduced complexity and significant cost savings with this revolutionary new product, allowing our customers and partners to deliver up to 30% more payload mass to orbit,” said Dan Polis, Vice-President of Engineering Solutions and Propulsion Systems at Sierra Space.
The use of hydrogen in space launches dates back much further than the energy carrier’s now desired climate-saving potential.
NASA has been using liquid hydrogen since the early 1960s. In combination with liquid oxygen, liquid hydrogen has been used as a rocket propellant across countless NASA launches.
Read more:How space flight’s hydrogen legacy could shape aviation’s future
Previously speaking to H2 View in 2021, Adam Swanger, Principal Investigator at the Cryogenics Test Laboratory, NASA’s Kennedy Space Center, said, “Once you’re out of the atmosphere and you’re in space, that’s where liquid oxygen and liquid hydrogen really shine from a performance standpoint.”
Despite its long use, hydrogen has proved troublesome for NASA.
In 2022, liquid hydrogen leaks waved off the launch of the Artemis I rocket twice in one week. The faults forced the agency to alter its design.
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