NASA has delayed the launch of Space Shuttle Atlantis to Friday 8 September because the STS-115 Mission Management Team (MMT) has decided it needed a further 24h to analyse a problem with the Orbiter's number one fuel cell.
An anomalous reading, never seen before, in the fuel cell's coolant pump motor alarmed Shuttle engineers yesterday. The Orbiter needs the fuel cells for onboard power. The MMT will meet today at 12:00 in Florida to assess the data gathered about the fuel cell issue and decide whether the launch will take place on Friday. A Friday launch has a 30% chance of weather conditions around the Kennedy Space Center prohibiting launch.
NASA's deputy orbiter project manager Ed Mango says, "We put together a huge amount of data, but it's not complete yet. We have to put all the data on the table and look at it. We'll need more time to understand what this signature really means."
If the problem cannot be resolved the Shuttle stack will have to be moved back to the vehicle assembly building. Although the current window to launch in daylight extends to 13 September NASA has only been able to extend the dates for lift off to 8 September. This is because of a scheduling conflict with the Russian Federal Space Agency's (FSA) Soyuz TMA-9 ISS crew transportation flight
NASA requires daylight launches to enable it to image the Shuttle as its ascends to monitor external tank (ET) foam debris loss. ET foam debris damaged the wing of Shuttle Columbia leading to its catastrophic re-entry break up on 1 February 2003. The Soyuz logistics conflict is because an Atlantis launch on 8 September will see the Shuttle stay at the ISS until 19 September. An 18 September launch of TMA-9 will mean it arrives at the space station on 20 September. Because a later Soyuz launch date would see the return flight of Soyuz TMA-8, which arrived at the ISS in March, land in darkness the FSA could not agree to NASA using the full daylight launch window.
However NASA could attempt to launch in late September or early October if they chose to relax the daylight launch rules. If the US space agency does not relax its rules the next daylight launch window is 26 October.
Source: FlightGlobal.com
