Radian One in Low Earth Orbit, an artist rendering. Credits: Radian Aerospace.

Radian One, A New Spaceplane Is Taking Shape

Radian Aerospace revealed the new design of its SSTO vehicle, Radian One, providing insights into its capabilities on the company's new website

After several tweets about component tests in the last three months, Radian Aerospace published on April 2, 2024, the new rendering and additional details of Radian One, its Single-Stage-To-Orbit (SSTO) spaceplane. The company announced the development of the vehicle two years ago when it emerged from stealth announcing its plans and a seed funding round of $27.5M.

With a crew of two to five members, Radian One will take off thanks to an innovative rocket sled, eliminating the need for a vertical launch system. The spaceplane will use its rocket motors to reach space. The ascent will be more similar to an airplane than to a rocket. Once in Low Earth Orbit, it could fulfill multiple missions like resupply for space stations and scientific research. It will need a compatible landing runway, with a 48-hour turnaround between flights and 90 minutes on-demand capability.


Rocket sled, an unusual stage zero

In a new video posted by Radian Space, the gray delta-wing-shaped spaceplane is taking off thanks to a rocket sled. The device has been in use since the Cold War to run acceleration tests on different technologies, also on humans.

A rocket sled is a carriage moving on rails and using rocket engines to accelerate. This configuration allows the sled to reach very high acceleration rates and speeds on the ground. Such conditions are hard to achieve with other technologies.

One of today’s applications is to run experiments for space exploration devices like testing inflatable and parachute decelerators to slow spacecraft before landing on Mars.

NASA Fires Up Rocket Sled Hardware at China Lake. Credits: NASA.
NASA Fires Up Rocket Sled Hardware at China Lake. Credits: NASA

Even if theorized and described in sci-fi novels since the 1950s, Radian Space is a forerunner in using a rocket sled as a stage zero for the takeoff of an SSTO at supersonic speed. In addition to being easily reusable, the rocket sled launch allows Radian’s engineers to design a spaceplane much lighter than the standard multistage orbital rockets, saving fuel and increasing the payload mass.


SSTO Reusable Launch Vehicle, the “holy grail” of spaceflight

A reusable SSTO has been defined as the “holy grail” of cheap spaceflight: low costs, quick turnaround between flights, and ready-to-fly in a short time.

Lockheed Martin X-33 was the first sub-scale technology demonstrator for such a vehicle, under NASA Reusable Launch Vehicle (RLV) program. After spending around 1 billion dollars overall, the project was closed due to technological issues with several components, including its composite-material fuel tank.

The X-33 was supposed to be the demonstrator for VentureStar, the orbital spaceplane replacement for the Space Shuttle. Due to the problems of the X-33 development, also the VentureStar program was closed.

Artist’s Conception of X-33 in Flight, with Aerospike Engine Firing, a predecessor of Radian One. Credits: NASA.
Artist’s Conception of X-33 in Flight, with Aerospike Engine Firing, a predecessor of Radian One. Credits: NASA

Radian Space can leverage more than ten years of advancements in composite materials science to fix the X-33 issues. Livingston Holder, Radian’s co-founder and chief technology officer, knows the challenge since he was part of the team working on the X-33.

“Materials have improved significantly on the composite side. There’s been a lot of learning,” he said in an interview.

A prototype vehicle of Radian One should be ready in 2024, while the full-scale spaceplane should fly for the first time by the end of the decade, just in time to serve the future commercial space stations.


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Giancarlo Albertinazzi

Giancarlo Albertinazzi

Space Ambassador, Terranaut, Future Spacepolitan, Writer of Becoming Spacepolitans Blog

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