Astronauts can be strapped into their assigned return vehicle and ready to undock within minutes in a true emergency. Actual landing is gated by orbital geometry and weather at recovery sites. In the fastest cases, a crew can undock and be on Earth in roughly 3 to 6 hours, although returns more often take 6 to 24 hours because deorbit windows and recovery teams must align.
How quickly can astronauts evacuate the ISS?
Minimum timelines are driven by two factors: how fast the crew can ingress their spacecraft and close hatches, and when the next safe deorbit opportunity occurs over an approved landing zone. Crews train to reach their vehicles rapidly, and both Crew Dragon and Soyuz are kept in a quiescent lifeboat state while docked. Once a deorbit window opens, the sequence from undocking to touchdown can be a few hours.
Recent returns illustrate the range: NASA’s Crew Dragon missions have gone from undock to splashdown in about 6 to 19 hours depending on phasing and weather (NASA Commercial Crew mission logs), while a Soyuz undock-to-landing profile has been completed in roughly 4 hours (NASA press release).
In a station emergency, the crew can also shelter inside their spacecraft, suited and strapped in, while waiting for the next viable deorbit pass rather than staying elsewhere on the ISS.
How does an ISS emergency return work?
- Ingress and safing: Crew don suits, move to their assigned seats, power up the vehicle, and close ISS and spacecraft hatches.
- Undock and depart: The spacecraft executes an automated undock and separation burns to back away from the station.
- Phasing to a landing zone: If a deorbit opportunity is immediately available over an approved zone, the crew may proceed quickly. Otherwise they wait in free flight for the correct ground track.
- Deorbit burn: A targeted retrograde burn lowers the perigee into the atmosphere over the landing area.
- Entry, descent, and landing: Thermal reentry, parachute deployment, and touchdown or splashdown. Crew Dragon lands in the ocean near Florida, Soyuz lands on land in Kazakhstan.
- Recovery and medical handoff: Recovery forces rendezvous, perform initial checks on scene, then fly the crew to medical facilities.
Emergency procedures are practiced regularly, and the docked spacecraft are treated as lifeboats for fire, depressurization, or toxic release contingencies (ESA: Emergencies on the Space Station).
What limits how fast the crew can land?
- Orbital mechanics: You can only deorbit into specific corridors when the station’s ground track passes an approved landing zone. That alignment typically yields one or more opportunities per day for each zone.
- Weather and daylight: Sea states, winds, lightning, and visibility drive go or no-go decisions for Crew Dragon’s seven designated splashdown areas off Florida. Bad weather can push a return to the next pass (NASA Commercial Crew updates).
- Recovery asset positioning: Ships, helicopters, and medical teams must be staged to meet the capsule promptly. Faster is possible if assets are already on station near a viable zone.
- Vehicle and crew health limits: Mission control may avoid higher G profiles or rough seas if a medical condition could be worsened.
SpaceX notes that Dragon is designed for crew-initiated contingency deorbit and rapid recovery, but every return still requires a targeted burn and a prepared recovery team (SpaceX Dragon overview).
Crew Dragon vs Soyuz: what are the emergency return profiles?
Crew Dragon targets ocean splashdowns near Florida with recovery ships prepositioned. Nominal reentry loads are about 3 to 4 g, and hatch opening on deck typically occurs within tens of minutes, followed by helicopter transport to shore and full medical evaluation (NASA Commercial Crew).
Soyuz targets the Kazakh steppe. A nominal guided reentry produces peak loads around 4 to 5 g. In contingencies Soyuz can fly a ballistic reentry, which is safe but harsher and can reach approximately 8 g, shortening cross-range and time to the ground. Russian and NASA recovery teams meet the capsule within minutes of touchdown for immediate medical support.
Is there precedent for a medical evacuation from the ISS?
As of 2024, there has been no publicly reported case of an ISS crew making an early return solely due to a medical emergency. Medical issues have been managed on orbit, including a documented in-flight venous thrombosis treated with anticoagulation and close ground support, without evacuating the astronaut (New England Journal of Medicine).
This reflects a strategy of robust onboard medical capability and telemedicine. The station carries a comprehensive medical kit, ultrasound, pharmaceuticals, and each increment includes a trained Crew Medical Officer supported 24/7 by flight surgeons on the ground (NASA Human Research Program). Early return remains available if a condition cannot be safely managed in space or if vehicle issues require it.
What does the ride back feel like for an ill or injured crewmember?
Both vehicles impose elevated G loads during reentry that can be uncomfortable even for healthy crew. Mission control can adjust timelines to avoid the most taxing profiles, aim for calmer seas, and expedite post-landing care. After splashdown or touchdown, recovery teams perform immediate medical checks, provide fluids and anti-nausea medication, and rapidly transport the astronaut to a hospital if needed (NASA Commercial Crew).