Planned launches to ISS

Soyus 30S crew in training at HoustonFollowing several weeks of speculation, plans for the next tranche of launches to the International Space Station are firming up. With cancellation of the Dragon launch planned for 7 February and a delay to the launch of the next Soyuz to the ISS, a cloud of uncertainty has hung over the ability of flight controllers to maintain progress toward restoring the science time aboard the station following the delay in Russia’s Soyuz launches late last year. Now, with further delays, managers are reworking the timelines.

A week ago pressurization tests on Soyuz 704, a TMA model assigned to fly the 30S mission to the ISS in late March, caused the descent module to fail in an area where hydrogen peroxide thrusters were installed. It is customary to apply a positive pressure above ambient values overnight to determine the integrity of the pressure vessel but leaks in spot-weld joints indicated an over-pressurization which rendered the entire module suspect. As a result, Soyuz 704 has been declared unusable and Soyuz 705 has been pulled forward for the 30S flight. This flight is now scheduled for 15 May carrying Padalka, Revin and Acaba to the ISS.

Launched on 14 November 2011, 28S is scheduled to return to Earth on 30 April with the Expedition 29 crew of Burbank, Ivanishin and Shkaplerov. Before that, the Progress M-15M cargo-tanker (ISS-47P) will be launched to the ISS on 20 April instead of 25 April as originally planned, clearing the departure of 28S. The return of the Expedition 29 crew will leave the ISS with a three-person crew for two weeks until the arrival of 30S in mid-May. At present 31S carrying Malenchenko, Williams and Hoshide is not expected to fly before July 2012.

Meanwhile, postponed from 7 February, the Dragon logistics module has been assigned a launch date no earlier than 20 March, although managers are doubtful that there will be sufficient time to prepare the vehicle for flight by that date, preferring to expect a launch in early April some time. NASA is pleased with the performance of SpaceX and ISS managers are in almost daily contact with the CEO of SpaceX as confidence builds toward the first commercial cargo flight to the station.

As for productive activity aboard the ISS, planners have accelerated a return to the average 35hrs/week of productive science work assigned to Increments 29/30. In fact the crew have got ahead so well that they pushed out almost 60hrs this last week in an attempt to build back the average which had been hit when the ISS was manned by a crew of only three late last year.

The Editor (Spaceflight)

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