Plan for an Astronaut Detached During a Spacewalk from the ISS

Spacewalking or extravehicular activity (EVA) is a critical but relatively safe process when astronauts are properly prepared and equipped. While most depictions in popular media may suggest that an astronaut could easily fend for themselves in space, such scenarios are far from reality. Astronauts are vigilant about their safety and have backup systems to ensure their return to the International Space Station (ISS) in the event of an unplanned detachment.

Stay Grounded with Tethers

Contrary to popular belief, astronauts do not just float away during a spacewalk. They are always tethered to the ISS for safety. These tethers ensure that even if an astronaut loses their grip, they are still securely connected to the spacecraft. If an astronaut does lose their grip, they can use their Emergency Maneuvering Unit (EMU) to regain contact with the station.

Orbital Mechanics and Rescues

If an astronaut is detached, there is no immediate rescue, but there is a specific protocol. Due to the nature of orbital mechanics, it would take about 46 minutes for their orbital path to re-cross that of the ISS. During this time, their crewmates would wait and then rendezvous with them at their new position. One of their crew members would then catch them and help them return to the ISS.

Note: It is important to highlight that the film "Gravity" inaccurately portrayed some aspects of orbital mechanics, leading to a misconception that could be dangerous for public understanding of space safety.

SAFER: A Lifesaving Tool for EVA Rescue

For more direct emergencies, astronauts have the SAFER (Simplified Aid For EVA Rescue) pack, a lightweight maneuvering system designed specifically for rescue missions. The SAFER pack is a stripped-down version of the Mobility Equipment Test Article (MET), used during the Space Shuttle era. It contains a compressed nitrogen system that can change an astronaut's velocity by about 3 m/s (approximately 10 ft/s) in any direction.

SAFER helps astronauts recover from any accidental slips or falls. It is designed to be similar to wearing a life jacket, providing necessary maneuvering capabilities without the complexity of larger systems. While it is an invaluable tool for most scenarios, SAFER has its limitations. If an astronaut were to be cast away by an explosion, depressurization, or any other severe event, SAFER might not be sufficient for a safe return. However, the likelihood of such an event is kept to a minimum through strict protocol and safety measures.

Putting safety first, astronauts and ground support teams focus on preventing any untoward incidents, as safety is the highest priority for all space missions.

Conclusion

Astronauts on spacewalks from the ISS are equipped with the necessary tools and procedures to deal with emergencies, ensuring a secure return to the space station. While detachments during an EVA are rare and complex, the strategic planning and backup systems provide a safety net for all crew members.