Despite hopes for a launch before the end of the year, NASA has decided to hold the STS121 mission, originally scheduled to launch in September, until March of next year. This gives NASA engineers a full seven months to redesign the PAL ramp foam to eliminate a repeat of the foam shedding incident that marred the STS114 "Return To Flight" launch last month.
Plans are also being formulated for a May 2006 launch for STS-115 using Atlantis. Planning for missions STS-116, STS-117, and STS-118 is more or less on hold with staff told to "do no negative work."
In a news conference today, NASA administrators laid out the details of the work to be done between now and March, with "minimizing" foam shedding now the admitted goal. Engineers have come to grips with the fact that is impossible to eliminate the tank foam problem that has plagued the Space Shuttle from its very first launch. NASA officials have admitted that they were "very lucky" that other shuttles did not experience the level of damage that caused Shuttle Columbia to break up during reentry, killing all aboard.
NASA Administrator Michael Griffin and Associate Administrator for Space Operations Bill Gerstenmaier made the announcement today at a news conference at the agency's headquarters in Washington.
"We are giving ourselves what we hope is plenty of time to evaluate where we are," said Administrator Griffin. "We don't see the tasks remaining before us being as difficult as the path behind us."
Based on NASA's self-imposed optimum lighting requirements, the earliest possible launch opportunity for the STS-121 mission is March 4, 2006. The Space Shuttle Discovery will be used for the mission, instead of Space Shuttle Atlantis.
Moving toward a no earlier than March launch for STS-121 will allow engineering teams more time to properly evaluate the issue of large pieces of insulating foam that came off Discovery's external fuel tank during launch last month. Targeting March also allows the Space Shuttle Program to put itself into a better posture for future Shuttle missions to the Space Station. Changing Orbiters for the STS-121 mission enables use of Atlantis for the following mission, STS-115, which will resume assembly of the Station.