Spacecraft flight delays following the crash of an unmanned Russian space cargo ship last week may result in the International Space Station operating without any astronauts for a period of time.

Michael Suffredini, NASA’s space station program manager, said at a news conference Monday that the next astronaut-staffed flight to the space station has been delayed from September to early November at the earliest.

That means the six crew currently on the station may all have returned to Earth before a new crew heads up there.


The last time NASA considered leaving the space station crewless was following the loss of the space shuttle Columbia and its crew in 2003. ((NASA))

The Russian Progress spacecraft, which had been carrying almost three tonnes of supplies for the space station, fell back to Earth after the third stage of its booster rocket failed a few minutes into its launch last Wednesday. The rocket is the same one used to launch the manned Russian Soyuz spacecraft, which is the main vehicle carrying crew to the space station since the U.S. retired its space shuttle program in July.

Suffredini said Russia wants to be sure the issue with the rockets has been resolved: "We’ll have a couple of unmanned flights before we put  humans aboard the Soyuz."

The return of at least some of the six astronauts currently aboard the space station is also expected to be delayed as Russia’s space agencies investigate last week’s crash. Three of the crew scheduled to return on Sept. 8 could stay until mid-September. The other three are scheduled to return on Nov. 16.

The delay of the September flight will allow the Russian Federal Space Agency to focus on its investigation into the cause of the failure of the rocket that carried the Progress spacecraft, develop a plan to correct it and figure out any implications for the launch of crews on similar rockets.

Suffredini said the space station can operate "indefinitely" without crew as long as there are no "significant anomalies." Most operations can be automated, and those that require human intervention, such as manoeuvres to avoid space debris, can be commanded from the ground.

Risk to space station

However, the risk of losing the space station is greater when there is no one on board, Suffredini acknowledged. That is why the last time NASA considered leaving the space station crewless, following the loss of the space shuttle Columbia and its crew in 2003, it eventually opted not to do so.

Suffredini said so far the Russian investigation shows that last week’s failure was linked to a loss of pressure between a pump and the rocket’s engine, prompting a computer to shut down the engine prior to a dramatic failure. As of Monday morning, the remains of the spacecraft have not been found. It's believed to have fallen in pieces in a heavily wooded, mountainous, sparsely populated area of Russia.

When asked if a similar failure would have been fatal if it occurred on a rocket carrying a Soyuz capsule full of astronauts, Suffredini said, "No."

He added that the Soyuz capsule, unlike the Progress, is capable of separating from the rocket during that part of the launch and could safely return to Earth.

According to the Canadian Space Agency, it's too early to tell whether the delays underway as a result of the Progress crash will affect the flight of Canadian astronaut Chris Hadfield in November 2012. He is scheduled to ride a Soyuz spacecraft to the International Space Station for a six-month mission. He will become the first Canadian to take command of the space station.