Radian Aerospace is set to use a rocket-powered sled to launch its spacecraft, capable of taking off and reaching orbit with 5 passengers and 2,267 kg of cargo.
Simulation of the Radian One spacecraft in operation. (Image: Radian Aerospace)
An American aerospace company plans to bring to life a spacecraft model that NASA once hoped to develop. In the 1990s, NASA, in collaboration with Boeing, decided to develop the VentureStar or X-33, a single-stage reusable launch vehicle. However, development was halted due to the immaturity of composite materials intended for the vehicle. Currently, Radian Aerospace’s Radian One aims to become the world’s first single-stage reusable spacecraft operating in low Earth orbit, as reported by Interesting Engineering on September 3.
Vertical takeoff is essential for sending spacecraft into space. The X-33, designed as a single-stage-to-orbit (SSTO) vehicle, aimed to revolutionize space travel by eliminating the multiple stages common in conventional rockets. Instead of jettisoning parts during ascent, the X-33 was designed as a fully reusable vehicle. It will launch vertically like a rocket and land horizontally on a runway, significantly reducing the cost of sending 0.5 kg of cargo to orbit from $10,000 to $1,000.
While efficient, rockets are very expensive due to reliance on multiple disposable stages.
After the project was shelved, Livingston Holder, who managed the X-33 at NASA at the time, revived the idea. Holder is one of the co-founders of Radian and the company has successfully tested its first full-scale engine. According to Radian, advancements in technology since 2001 have made the construction of such spacecraft more feasible. “We have lightweight, durable composite materials with greater thermal ranges than in the past. The thrust is also better than anything we have ever had in terms of fuel efficiency and system weight,” Holder shared.
While efficient, rockets are very expensive due to their reliance on multiple disposable stages. Companies like SpaceX have reduced costs with reusable rockets such as the Falcon 9. However, spacecraft require less fuel and do not need multiple stages, potentially providing a more affordable and accessible solution for space travel. Radian’s approach in Washington includes a sled powered by a rocket that travels along a 3.2 km track, reaching speeds of 864 km/h. Once the sled releases the spacecraft, the vehicle continues its journey to orbit using its own engines. Once complete, the Radian One, the company’s first spacecraft, will be capable of carrying 5 passengers and 2,267 kg of cargo to orbit.
Radian One uses 3 liquid-fueled engines, launching from a standard runway, reaching an appropriate altitude, and then firing its rocket engines to enter orbit. According to the company, the vehicle will stay in orbit for up to 5 days before re-entering the atmosphere. With its wings, the spacecraft can land on any runway that is at least 3,048 m long, refuel, and depart for another mission in less than 48 hours. This spacecraft is designed for up to 100 reuses.
Radian is confident in overcoming SSTO challenges with 3 key technologies. First, their sled-launch system provides power for both its own engines and the spacecraft, ensuring the vehicle has a full fuel tank at launch. Second, the ultra-light landing gear is specifically designed for touchdown. Third, the wings, which are unprecedented on vertically launching rockets, provide lift, reducing the thrust requirements during ascent. According to Radian, a small-scale model will be tested this year, with full-scale flight tests scheduled for 2028.
