Saturday, October 29, 2011

Soyuz Rocket Poised for Make or Break Launch to Space Station

30 October 03:29 Note:  Progress 45 successfully launched to orbit. Docking on Wednesday.

In a critical step towards restoring flights to the International Space Station a Soyuz rocket is set to launch a Progress freighter tomorrow. This is the first flight to the ISS since a third stage engine failure of a Soyuz rocket sent the Progress 44P cargo ship crashing into Siberia on August 24. A failure on this launch will lead to the temporary de-crewing of the space station.

The Soyuz rocket is scheduled to launch the Progress 45P spacecraft at 03:11 am PDT (10:11 GMT) from Baikonur Cosmodrome in Kazakhstan. It's scheduled to dock with ISS two days later.

After the crash, all flights of the Soyuz rocket were halted while the cause of the failure was investigated. Since manned Soyuz spacecraft use the same booster, crewed flights to the ISS were also halted. This lead to the station's crew size being reduced to 3 when Expedition 28 returned to Earth in September.

The cause of the failure was eventually traced to a contaminated fuel line and the Soyuz rocket was cleared to fly.  Since the crash two Soyuz rockets have been successfully launched, though they were not configured identically to the failed booster. Tomorrows Progress 45P is the first time the same configuration has been flown since the accident.

A successful launch will pave the way for sending the manned Soyuz 28S spacecraft to the ISS on November 14.  A failure will undoubtedly delay it.  With the current ISS crew scheduled to leave on November 22, this would leave the ISS unmanned.

How reliable is the Soyuz rocket? According to Jonathan's Space Report the Soyuz FG, used to launch crews to the International Space Station, has a 100 percent success rate since 2001. By comparison, the Soyuz U, which failed in launching Progress 44P, has had 20 failures in 761 launch attempts since 1973. That translates to a 97.4 percent success rate.

Credit: Roscosmos and Energia