Russia’s Progress 44 supply capsule, filled with 5,900 lb. of supplies for the International Space Station, crashed back to Earth shortly after launching onboard a Soyuz rocket early Aug. 24, injecting uncertainty over future cargo and crew transport plans early in NASA’s post-shuttle era.

The unpiloted space freighter commanded a shutdown of the third stage in response to an engine anomaly 325 sec. after lifting off from the Baikonur Cosmodrome in Kazakhstan at 9 a.m. EDT, or 7 p.m. local time. The third stage with the Progress plummeted into the Altai region of the Russian republic.

NASA’s STS-135 flight, a station re-supply mission that marked the end of the U.S. space agency’s 30-year shuttle program as it touched down on July 21, left the orbiting research lab fortified with supplies at least through March. However, the Soyuz-U variant that initiated the failed Progress mission has hardware similarities with the Soyuz-FG version, the only rocket available to transport astronauts to the space station in the shuttle’s absence, says NASA’s Mike Suffredini, International Space Station program manager.

“Obviously, this has implications for the vehicle on orbit and the crew,” Suffredini told a Johnson Space Center news briefing.

NASA expects to participate in the Russian investigation of the Soyuz failure, though the format for a formal inquiry was still being addressed, he said.

The U.S. crew transportation services that NASA is nurturing under the Commercial Crew Development initiative are not forecast to begin operations until 2015-16.

In the near term, the Aug. 24 failure could delay plans to return the Expedition 28 crew of Andrey Borisenko, Alexander Samokutyaev and Ron Garan to Earth onboard the Soyuz TMA-21 on Sept. 7, after 156 days in orbit. Prior to the loss, they were scheduled to be replaced by the launch of two Russians and an American onboard the Soyuz TMA-03M on Sept. 21, restoring the orbital base to the desired six-person crew operation.

Borisenko, Samokutyaev and Garan could remain in orbit for an additional one to two months, Suffredini says. Mission managers would prefer to time the launching of a Soyuz replacement crew until after a successful Progress flight and about two weeks before the Expedition 28 veterans return to Earth, Suffredini says.

Progress 45 and 46 launches had been tentatively scheduled for late October and late December. However, a long-running investigation and recovery from the Progress 44 loss could force the U.S.-led, 15-nation space station partnership to cut the crew size to three astronauts. A reduction in the crew would greatly impact the surge in scientific station research and technology demonstrations anticipated as the near 13-year assembly and outfitting of the station came to a close with the final shuttle flight.

NASA’s STS-135 mission in July onboard Atlantis delivered a year’s worth of supplies to the station to bridge the gap between the shuttle’s final mission and the start of U.S. commercial re-supply missions.

SpaceX, one of two emerging providers, is aiming for the Nov. 30 launch of an ambitious demonstration mission that would attempt the first space station berthing by a U.S. commercial supplier.

However, with the possible exception of some spare parts for the station’s toilet, the Atlantis flight provided enough food and other supplies to sustain six astronauts through 2012 without deliveries from SpaceX or from Orbital Sciences, the second commercial supplier, Suffredini says.

The Progress 44 was to dock with the station on Aug. 26, filling the Russian segment aft docking port vacated by the Progress 43 on Aug. 23. The new freighter was to serve as the propulsion source for orbital adjustments and orbital debris avoidance maneuvers by the more than 900,000-lb. orbital outpost.

Europe’s Automated Transfer Vehicle II boosted the station to record altitudes before its departure in June, easing some of the re-boost requirements. The orbiting lab, circling the Earth at a mean altitude of 240 mi. before the Progress loss, can rely on Russian segment thrusters in the Zvezda service module for maneuvers.