Despite the fact that it planned on building on the momentum caused by the STS-125 shuttle repair mission to the Hubble Space Telescope, NASA found itself forced to consider delaying the STS-127 assembly mission to the International Space Station (ISS) by at least a day. The seven-astronaut crew that will fly to the orbital lab will use the shuttle Endeavor, which is currently still on Launch Pad 39B, at the Kennedy Space Center, in Florida. Severe weather and powerful thunderstorms prevent the agency's engineers from moving in and making the necessary arrangements so that the orbiter could be moved to Launch Pad 39A, its designated take-off site.

Initially scheduled to blast off on June 13th, the STS-127 mission is scheduled to deliver the last segments of the Japanese Kibo module to the space station, the Exposed Facility (JEM EF), and the Exposed Section of the Experiment Logistics Module (ELM-ES). The shuttle will also replace the first long-term JAXA astronaut aboard the ISS Koichi Wakata with NASA flight engineer Timothy Kopra. At this point, Endeavor has just been decommissioned from the STS-400 rescue mission. While the space shuttle Atlantis was in orbit repairing Hubble, Endeavor was also docked at the KSC, so that it could intervene if its sister ship got irreparably damaged.

It's essential for NASA not to miss this launch window, which only spans three days. Things are about to get very tight, officials have told Space, because the planned Saturday Endeavor roll-out, from one launch pad to the other, has already been pushed back by a day. If the weather doesn't break, then further delays could be expected. “Really, if we don't start to roll on Saturday, then it's going to be a day-for-day impact for the launch.It's getting very tight,” NASA's space shuttle Program Manager John Shannon said on Thursday.

If NASA misses the June 15th deadline for the launch, then it would have to stand down with STS-127, and allow for the June 17th launch of the Lunar Reconnaissance Orbiter and the Lunar CRater Observation and Sensing Satellite (LCROSS). The mission has already experienced a series of delays, and NASA cannot afford to keep the two instruments grounded for long. Once this launch is completed, the next window for STS-127 will be on July 12th.

Mission planners say that the option will remain opened, as they do not want to rush engineers to get everything done in June, if the weather doesn't cooperate. In addition, Shannon adds that, even with the one-month delay, NASA's launch schedule for this year will not be modified. The space agency plans to launch at least two more shuttle missions until the end of the year, the manifesto explains.