Why Astronauts Are Stuck on a Two-Day Trip to the Space Station

The fast track to outer space is temporarily out of service.

Sep 2 2015, 4:29pm

Launch of new ISS crew, September 2, 2015. Image: NASA TV

Two days is a long time to be stuck with two other dudes in a cramped space capsule. Then again, it's preferable to putting the ISS at risk of a Gravity situation, and that's exactly why a trio of astronauts are currently facing a very long detour in their spacebound commute.

Early this morning, three astronauts were successfully launched from Baikonur Cosmodrome in Kazakhstan, and are currently on their way to the International Space Station. The Soyuz spacecraft they're riding in transports crews to and from the station many times a year, typically delivering the astronauts to the ISS about six hours after launch.

But this trip is different. The new crew—consisting of Russian commander Sergey Volkov, Danish astronaut Andreas Mogensen, and Kazakh cosmonaut Aidyn Aimbetov—is expected to arrive at the station a full two days from now, on the morning of Friday, September 4.

Today's ISS crew launch. Video: ESA/YouTube

The longer flight time is due to a so-called Pre-Determined Debris Avoidance Maneuver (PDAM), that took place back on July 26. The ISS ground team detected debris from the fallout of the 2009 Iridium 33 satellite crash in the orbital pathway of the ISS, and fired the station's jets to nudge it about a kilometer higher into orbit to prevent a collision.

PDAMs are fairly common on the ISS, but in this case, the maneuver has resulted in the ISS orbiting at a much higher altitude by the time this crew launch rolled around. Usually it takes about four trips around the Earth (lasting a cumulative six hours) for the Soyuz to catch up with the ISS in orbit. For Volkov's crew, it will take 34 orbits, so the crew will be really ready to stretch their legs when they finally dock with the station on Friday.

Aimbetov, Volkov, and Mogensen. Image: NASA

Incidentally though, for most of the ISS's history, the two-day, 34-orbit commute was the standard way to reach the station. The first "express" six-hour trip debuted only two years ago, on March 28, 2013 with Expedition 35. So while the fast track is certainly the preferred option, it's not that abnormal for a crew to take the scenic route, especially in the wake of a PDAM.

In any case, Mogensen and Aimbetov will likely want to savor any time off-Earth that they can, no matter the setting. It is the first trip to space for both men, and it won't last long. The pair will depart the ISS on September 11, along with Expedition 44 commander Gennady Padalka. Volkov, meanwhile, will stay on until March 2016.