Modern spacesuits have a compatibility problem. Astronauts’ lives depend on fixing it

Suni Williams and Butch Wilmore, the Nasa astronauts who were stuck on the International Space Station (ISS) for nine months, have finally returned to Earth.

Spacesuits were an important consideration that Nasa had to factor into its plans to bring the astronauts back home. Wilmore and Williams had travelled to the ISS in Boeing’s experimental Starliner spacecraft, so they arrived wearing Boeing “Blue” spacesuits.

Following helium leaks and thruster (engine) issues with Starliner, Nasa decided it was safer not to send them back to Earth on that vehicle. The astronauts had to wait to return on one of the other spacecraft that ferry crew members to the ISS, the SpaceX Crew Dragon.

This meant they needed a different type of spacesuit, made by SpaceX for use in its vehicle only. Boeing’s suits cannot be used in Crew Dragon in part because the umbilicals (the flexible “pipes” that supply air and cooling to the suit) have connections and standards that don’t work with the ports inside a Crew Dragon.

This highlights a general problem for the growing number of space agencies and companies sending people into orbit, and for planned missions to the Moon and beyond. Ensuring that different spacesuits are compatible, or “interoperable”, with spacecraft they weren’t designed to be used in is vital if we are to protect astronauts’ lives during an emergency in space, especially in joint missions.

The spacesuits worn during a return from space are called “launch, entry and abort” (LEA) suits. These are airtight and provide life support to the astronauts in case there is a decompression, when air is lost from the cabin.

Unfortunately, a decompression has already caused loss of life in space. During the Soyuz 11 mission in 1971, three Soviet cosmonauts visited the world’s first space station, Salyut 1. But during preparations for re-entry, the crew cabin lost its air, killing cosmonauts Georgy Dobrovolsky, Vladislav Volkov and Viktor Patsayev, who were not wearing LEA suits. All cosmonauts wore them after this incident.

As well as the connections for life support, the Boeing and SpaceX suits also have restraints and connections for communications that are specific to each vehicle. For their return home from the ISS in a SpaceX capsule, Williams was able into use a spare SpaceX suit that was already aboard the space station and the company sent up an additional suit on a cargo delivery for Wilmore to wear.

Two spacecraft are usually docked at the ISS as “lifeboats” to evacuate the astronauts in the event of an emergency. These are generally a SpaceX Crew Dragon and a Russian Soyuz capsule.

If an emergency evacuation were to occur and there weren’t enough of the right spacesuits available – for either the Crew Dragon or Soyuz – it could endanger astronauts during the fiery re-entry through Earth’s atmosphere. Interoperability between spacesuits has therefore become a matter of survival.

The Outer Space Treaty, which provides the basic framework for international space law, recognises astronauts as “envoys of humankind” and grants them specific legal protections. These were expanded on in subsequent UN treaties – notably the Rescue Agreement, which imposes a range of duties on states to render assistance to each others’ astronauts in cases of emergency, accident or distress.

For the ISS, a collaborative space programme with international flight crews, protocols include terms that set forth how this obligation is to be met. However, these protocols do not contain terms relating to spacesuit interoperability.

Risks to astronauts in space

A major potential cause of an emergency evacuation is space debris. The ISS has regularly had to manoeuvre to avoid collisions with debris – including entire defunct satellites.

In his memoir, Endurance, Nasa astronaut Scott Kelly describes being commanded to enter the Soyuz vehicle with two other crew members and prepare to detach from the ISS because of a close approach by a large defunct satellite. Luckily, the spacecraft passed by harmlessly.

As orbits become increasingly congested, with an exponential increase in the number of space objects being launched, the risk of collisions will also increase.

Ever more companies and governments are entering the human spaceflight arena. The Tiangong space station, China’s orbiting laboratory, has been fully operational since 2022, and there are plans to open it to space tourism, just like the ISS.

India is planning to join the community of nations with the capability to launch humans into space, under a programme called Gaganyaan. And while most space travellers remain government-funded astronauts, the number of private space-farers is increasing.

Billionaire Jared Isaacman (who is President Trump’s nominee to run Nasa) has commanded two private missions into orbit using Crew Dragon. On the second of these, he participated in the first spacewalk by privately funded astronauts. The ISS is set to be retired in 2030 – but one company, Houston-based Axiom Space, is already building a private space station.

Against this complex and part-unregulated backdrop, ensuring the interoperability of different spacecraft systems, including spacesuits, will increase levels of safety in this inherently risky activity.

While the safety and practicality of spacesuits has always been the top priority, compatibility between different suits and vehicles should also be high on the list. This requires space agencies and private spaceflight companies to engage with each other in a process to agree on standard interfaces and connections for life support and communications, across all their suits and space vehicles.

Amid this period of increased commercialisation and competition between the organisations and companies involved in orbital spaceflight, a move toward greater collaboration can only be a good thing.

This article first appeared in 'The Conversation' on 25 March 2025.