EXPLAINER: How a space station air leak delayed the Axiom-4 mission further

NASA and Axiom Space have put their upcoming private astronaut mission on hold after discovering new problems with an air leak that has been troubling the International Space Station (ISS) for years. The Ax-4 mission, which was supposed to send private astronauts to the space station, has been delayed further. This decision came after space agencies noticed unusual pressure readings in a part of the station that has been leaking air since 2019.

The problem is located in the Russian section of the space station, specifically in a part called the Zvezda service module. Think of this module as one of the main rooms of the space station where astronauts live and work. The leak is happening in what’s called a “vestibule”—imagine it as a connecting hallway or corridor that links different parts of the space station. This particular vestibule, known by its technical name “PrK,” is like a gateway that connects a docking port (where spacecraft attach) to the main living areas,” explained space analyst Girish Linganna.

So why is this vestibule so important? It’s the pathway that astronauts use to move between the Russian cargo ships (called Progress spacecraft) and the rest of the station. When supply ships arrive with food, equipment, and other essentials, astronauts need to pass through this vestibule to unload the cargo. However, the good news is that this leaky vestibule is not the only place where spacecraft can dock at the space station. The ISS is like a busy airport with multiple gates for different types of aircraft.

The ISS has a total of eight connection points, with four docking ports on the Russian segment. These use a probe-and-drogue system (like a cone and stick mechanism) and can handle Russian Soyuz crew ships and Progress cargo vessels. On the other hand, there are four berthing ports in the US segment. These include two modern International Docking Adapters for SpaceX Dragon and Boeing Starliner spacecraft, plus berthing mechanisms for cargo ships like Cygnus and Japanese HTV vehicles.

“If one parking space at a shopping mall is blocked, you can still park in the other available spots. Similarly, even though the Zvezda vestibule has problems, there are seven other connection points available for spacecraft,” remarked Linganna.

The space station requires multiple docking ports for several practical reasons. Different spacecraft have different plugs, much like your phone charger won’t fit into a laptop port. Russian and American spacecraft use completely different docking systems. Russian ships use one type of connection, while American and other international spacecraft use different designs. Space missions always need backup plans. If one docking port fails, others are available. It’s like having multiple exits in a building.

The space station regularly receives crew ships, cargo deliveries, and supply missions from different countries. Multiple ports allow several spacecraft to be connected simultaneously. There’s always at least one Soyuz spacecraft docked as an emergency lifeboat for the crew, while other ports handle regular operations.

However, reports point out that NASA is particularly worried because they fear this leak could lead to a catastrophic failure, meaning the vestibule could potentially break apart or fail altogether. This would be extremely dangerous for the astronauts on board. As a safety measure, when astronauts need to use this leaky vestibule, NASA takes extra precautions. They even close the hatch (door) between the American and Russian sections of the space station to prevent any potential problems from spreading.

“NASA and the Russian space agency (Roscosmos) don’t completely agree on how serious this problem is. NASA seems more concerned about the potential dangers, while the Russians appear less worried. This difference in opinion has made it harder to find a quick solution,” pointed out Linganna.

Russian cosmonauts have been inspecting the problem area and sealing additional spots where air might be escaping. The good news is that the module is currently holding pressure, meaning the immediate danger is controlled. SpaceX, the company that was ready to launch the Ax-4 mission, says they will work with NASA and Axiom Space to find a new launch date. However, this delay might affect other planned missions later in the year.

The postponement shows how seriously space agencies take astronaut safety as they would rather delay an expensive mission than risk putting people in danger. While this particular vestibule has been causing headaches for over five years, the space station’s multiple docking ports provide backup options, demonstrating the smart engineering that keeps our orbital outpost operational even when problems arise.

Sci/Tech