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Astronauts' Return to Earth Delayed by Loss of Russian Spacecraft

A preliminary investigation shows the third stage of the Soyuz rocket separated early

The launch failure and loss of an unmanned Russian cargo spaceship has prompted officials to delay both the return to Earth of some of the International Space Station's crew and the launch of their successors. The chief of Russia's Roscosmos space agency, Igor Komarov, said Tuesday that the April 28 launch mishap was caused by a leak of fuel tanks in the Soyuz rocket's third stage. A preliminary investigation showed the third stage separated early, Komarov said, leaving the capsule about 13 miles (20 km) short of its intended altitude. Left in low orbit, the Progress cargo spaceship fell to Earth over the Pacific on May 8. Officials said the need to pinpoint the cause of the malfunction and work out steps to prevent it from happening again has required changes in the schedule of following launches.

Three of the orbiting outposts' six-person crew — NASA's Terry Virts, European Space Agency astronaut Samantha Cristoforetti and Russian cosmonaut Anton Shkaplerov — had been scheduled to return this week. They've now been asked to stay in orbit until early June.

"They have accepted it with understanding and agreed to work an extra month or so in orbit," said Vladimir Solovyov, the head of the station's Russian segment. He said the launch of a replacement crew will be pushed back from late May to late July. That will be preceded by the launch of a Progress 60 cargo spaceship in early July to deliver several tons of food, fuel and supplies. NASA says the space station has sufficient supplies to support crews until the fall of 2015.

NASA astronaut Scott Kelly and Russian cosmonauts Mikhail Kornienko and Gennady Padalka will remain aboard the station to begin Expedition 44. The Soyuz spacecraft carrying Expedition 44's Kjell Lindgren of NASA, Oleg Kononenko of Roscosmos, and Kimiya Yui of the Japan Aerospace Exploration Agency will launch in late July from the Baikonur Cosmodrome in Kazakhstan.

Both the Soyuz spacecraft that delivers crews to the station and the Progress cargo spaceship are put into orbit by the Soyuz booster rocket, a workhorse of the Soviet and then Russian space program for more than four decades. Solovyov said that space officials foresee no further delays beyond the summer. He said that the flight of British soprano Sarah Brightman set for September should go ahead as planned.

Roscosmos expects to provide an update about the Progress 59 investigation on May 22.

— NBC News staff and Reuters contributed to this report.