A recent failure by Russia’s mainstay cargo rocket is likely to keep three astronauts aboard the International Space Station (ISS) more than a month longer than planned, the Russian agency Interfax reported on Monday citing space agency officials.

Currently six astronauts are aboard the ISS: Russians Aleksandr Samokutyaev, Sergei Volkov and Andrei Borisenko; the US’ Roland Garan and Michael Fossum; and Japan’s Satoshi Furukawa.

Samokutyaev, Borisenko and Garan were scheduled to return to Earth on September 8, but mission controllers last week ordered a delay in their departure in the wake of an August mission failure by Russia’s Soyuz rocket, the only booster capable of sending replacement astronauts to the ISS.

Russia’s national space agency currently is planning two unmanned missions with its Soyuz booster during October which, if successful, would become the green light for a manned Soyuz flight to the ISS, officials said.

The Soyuz mission to the ISS would take place in November “at the earliest” and so delay the departure of the three astronauts scheduled next to return to Earth by some 45 days, the report said.

One Soyuz “test” mission reportedly will carry a US Globalstar satellite into orbit on October 8, while an October 14 mission would deliver an unmanned Progress space vehicle carrying additional supplies to the ISS.

A Soyuz booster rocket launched on August 24 failed to place a communications satellite into proper orbit, with the transport module eventually crashing into a remote Russian province in Central Asia.

Russia’s national space agency ordered a halt to all Soyuz missions pending pending an investigation into the accident.

The end of service of the US space shuttle fleet in July has left Russia’s Soyuz rocket as the only booster that can lift a manned space vehicle to the ISS.

The ISS has food and water supplies sufficient to support crews aboard through December, according to Russian news reports.

If Russia is unable to deliver supplies and replacement crew to the ISS by the end of November, all astronauts aboard the station could abandon it via escape modules built into the ship, Nasa spokesman Michael Saffredini told US reporters on Sunday.

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