In case of an emergency, astronauts aboard the International Space Station (ISS) used to take refuge inside a Russian Soyuz space capsule docked at the orbiting lab. The vehicle had served as the crew's space taxi, their only means of getting to and from the ISS, since the Space Shuttle fleet was discontinued years ago.
While these vehicles, which launch from the Baikonur Cosmodrome in Kazakhstan, have proven to be a reliable transportation system for astronauts, they are not the ideal type that could transport sick or injured crewmembers back to Earth. According to former astronaut Stephen Robinson, who flew on four shuttle missions and currently serves as chairperson at the mechanical and aerospace engineering department at the University of California, Davis, there could be one particular space vehicle perfect for the job: the U.S. Air Force's X-37B space plane.
"If somebody needs to come home soon from space, coming back on the Soyuz is going to be a pretty challenging ride - at least 4.5 Gs, fairly violent landing, and then you might not be very close to the medical care you need out in Kazakhstan," Robinson said during a presentation with NASA's Future In-Space Operations (FISO) working group, as reported by Space.com.
According to Etan Halberg, a graduate student at UC-Davis who also talked during the presentation, one study indicated that "hard landings" of the Soyuz spacecraft could injure astronauts about 40 percent of the time.
Even vehicles developed by SpaceX and Boeing, which use similar capsule designs with parachute landings, could not be used as a space ambulance, ExtremeTech reports.
Halberg said that an astronaut ambulance should be able to stay at the ISS for two years or more at a stretch, could get crew back to Earth quickly (in a span of three hours), impose minimal G-loads on occupants, could land close to a hospital, and allow the injured or sick to lie in a supine position.
These requirements could be met by a space plane, Halberg said, and a good fit would be the X-37B space plane. The semi-secret space plane, which is in the middle of its fourth mission, would have a different ambulance version. Robinson is currently suggesting that the Air Force could repurpose the X-37B's design as an orbital rescue spacecraft, where it will feature a pilot (as a backup for the autonomous system) and enough room for two passengers (one patient and one medical officer).
Robinson and Halberg are also considering Sierra Nevada Corp.'s Dream Chaser space plane as another option. Dream Chaser, which looks like a smaller version of NASA's Space Shuttle, is set to fly in the United Nations' first-ever space mission in 2021.