Three ISS Crew Members May Have "Rocky" Return Overnight; Next Soyuz Launch Slips

Three of the six crew members aboard the International Space Station (ISS) are scheduled to return to Earth early tomorrow morning East coast time. Russian space analyst Jim Oberg reported in IEEE Spectrum last week that there are a few concerns about the new version of the Soyuz spacecraft that took them to ISS and will return them home. Meanwhile, the next Soyuz launch has been delayed, perhaps for as long as a month, due to technical issues.

American Scott Kelly and Russians Oleg Skripochka and Alexander Kaleri are the first crew to use the new “digital Soyuz,” an upgraded version of the Soyuz spacecraft with improved computers and avionics. Oberg writes that this spacecraft, Soyuz TMA-01M (which NASA calls Soyuz 24S), may have a “rocky” descent. He notes that NASA’s ISS On-Orbit Status Report for last Thursday revealed that after the three undock from the ISS, they will perform a test of roll rate sensors “in response to an instrumentation failure during ascent last year,” quoting the NASA report. Depending on the results, the crew will know if they can enjoy a normal, relatively comfortable reentry or have to rely on a ballistic entry mode that the Russians use as a backup. The ballistic reentry is a rough ride according to those who have experienced it.

The crew is due to close the hatches between the Soyuz and the ISS at 9:20 pm EDT tonight (Tuesday) and undock at 12:27 am EDT Wednesday, landing at 3:53 am EDT in Kazakhstan.

Oberg relates other recent problems with the Soyuz — both this new digital craft and others in the Soyuz TMA series — especially regarding maintaining proper cabin pressure. The Soyuz has evolved considerably from the first version launched in 1967, simply called Soyuz, to Soyuz T to Soyuz TM to Soyuz TMA.

In the past couple of days, the Russians have decided to delay the next launch, Soyuz TMA-21, which was due to take replacement ISS crew members to ISS on March 30. At first the delay was to be for 10 days, but today Russia’s Interfax news agency said it could be “a month or even more” according to a posting Oberg made to the Friends and Partners in Space listserve this afternoon circulating the Interfax story (a subscription is needed to access it online) The problem apparently is related to a condenser in the command communications system and the Russians are determining whether one or all of the condensers must be replaced. In the latter case, the launch could slip to April 20.

The ISS program is accustomed to launch date slips in the space shuttle program, but Soyuz delays are uncommon. That these problems are developing just as the shuttle program comes to an end highlights the challenges of having only one ISS crew transportation system to get people back and forth.

On the other hand, if the mission by happenstance is delayed to April 12, it could be launched in celebration of the 50th anniversary of Yuri Gagarin’s flight into space, which inaugurated the era of human spaceflight.