In the event of an emergency aboard the International Space Station (ISS), astronauts take refuge inside a Russian Soyuz capsule that remains docked at the station. These vessels have been the only means of getting to and from the ISS since the Space Shuttle was discontinued several years ago. While other vehicles are in development, none of them could effectively serve as a “space ambulance.” The best archetype for that design might be the mysterious Air Force X-37B space plane.
The Soyuz program is a reliable way of reaching the ISS and returning home, but it’s a little lacking in finesse. Reentering the Earth’s atmosphere in a Soyuz exposes passengers to at least 4.5G of force, and the parachute-aided landings are surprisingly violent. A study of Soyuz “hard landings” showed that minor injuries are sustained by astronauts approximately 40% of the time. Now, imagine if an astronaut were injured on the ISS. Sending them down in a Soyuz could make the situation much worse.
Even the vehicles being developed by companies like SpaceX and Boeing use similar capsule designs that land with parachutes (though SpaceX is also toying with propulsive landing). They might be gentler, but the best way to transport an injured astronaut would be with a space plane. Ideally, transporting an injured crew member back to Earth should include minimal G-loads and take no longer than three hours.
The Air Force’s semi-secret space plane is currently not suitable as an astronaut ambulance, but a private firm called Sierra Nevada is using the design as inspiration for its Dream Chaser space plane. The X-37B launches attached to a rocket and glides in for a landing, just like the Space Shuttle used to. This vehicle is currently in the middle of its fourth mission, which began in May 2015. This vehicle has logged millions of miles in space, proving that it’s an effective design. One notable difference is that Dream Chaser would be a piloted craft, whereas the X-37B is entirely remote.
It’s smaller than you think.
At the same time, former astronaut Stephen Robinson is promoting the idea that the Air Force could repurpose the X-37B design as an orbital rescue craft. Like the Dream Chaser, it would need to be a manned vehicle with a pilot as a backup for automated systems. There would be room for two passengers in addition; one patient and a medical officer. Robinson suggests that the revamped X-37B could launch to the ISS carrying cargo, then remain docked for use in the event of an emergency.
Both the reimagined X37B and the Dream Chaser are just hypotheticals right now, with no firm plans to begin construction. However, as human spaceflight accelerates, we will eventually need a space plane vehicle capable of softer landings.
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