Backup Soyuz can’t reach the International Space Station before late February

Zoom in / Soyuz spacecraft docked at the International Space Station.

Today, NASA held a press conference to describe the situation on the International Space Station (ISS) in the wake of a major coolant leak from the Soyuz spacecraft docked at the station. At the moment, neither NASA nor Roscosmos have a clear picture of their options for using the damaged spacecraft. If it is unusable in its current state, it will take until February to get a replacement for the International Space Station.

The Soyuz spacecraft is one of two vehicles used to ferry humans to and from the International Space Station, and serves as a “lifeboat” in the event that personnel request a rapid evacuation of the station. So, while the leak does not endanger the International Space Station or its crew, it cuts the margin for error and could interfere with future crew rotation.

As Roscosmos pointed out earlier this week, the cool-looking plume of matter arose from a millimeter-sized hole in the cryogenic radiator. Although the cooling system has redundant pumps that can handle failures, the leak resulted in the loss of all coolant, so there is nothing to pump at this point.

Sergey Krikalev, executive director of human spaceflight programs for Roscosmos, said ISS partners have already conducted an analysis that compares the crater’s orientation with the likely direction any small meteor might come from. The two do not match, so there is no indication of how the damage occurred. The coolant poses no danger to the outer surface of the International Space Station.

At the time of the damage, the next Soyuz launch to the International Space Station for crew rotation was scheduled for mid-March. Krikalev said that could be pushed forward a few weeks to late February, which could result in an undamaged lifeboat being transported to the station. Whether or not that carries a replacement crew will depend on whether the damaged capsule is deemed safe enough to return the current crew to Earth. (Soyuz can perform an automated docking at the station, so it can be sent to the International Space Station without a crew.)

However, for now, we are still not sure if the damaged Soyuz can safely return the crew to Earth in the absence of a system to cool its interior cabin. “As soon as we start the equipment and once the crew is inside the crew cabin, temperatures start to rise,” Krikalev said. “We don’t know exactly how high it will go up [get]and our specialists in Russia, together with specialists in Houston, will estimate the rate of temperature rise and the maximum temperature that can be reached during the various re-entry modes.”

These different modes include an option to reduce the amount of time Soyuz remains in space before re-entry. There’s also the option of what Krikalev called “analog re-entry,” which is essentially manual process control, allowing some of the internal electronics to be shut down. If any of these re-entry options prove viable, the Soyuz on the International Space Station could fulfill its role as a lifeboat despite the damage. Whether “viable in an emergency” is desirable for crew rotations is a separate matter.

“If the nominal entry is dangerous — or not safe enough, I would say, we’ll send a craft to get a good spacecraft for the crew,” Krikalev said. This vehicle will be empty, which means that the current crew will remain on the station for a long time, and the ISS will be without a lifeboat until its arrival. NASA’s Joel Montalbano noted that in this case, the damaged Soyuz would be sent through a null reentry to allow Roscosmos to obtain data regarding its behavior.

Meanwhile, things are returning to normal on the International Space Station, Montalbano said, with spacewalks underway to install solar panel upgrades. He said the next rotation of U.S. personnel remains scheduled to depart Jan. 9 aboard the Dragon spacecraft.

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