CAPE CANAVERAL, Fla. — NASA extended the first space shuttle mission in two and a half years by one more day on Monday, postponing a planned landing because of unfavorable weather conditions at the Florida landing site.
Discovery had two chances to land at Kennedy Space Center in Florida, but each time NASA decided against having the shuttle fire its engines for descent. The first landing opportunity was called off due to concerns about low cloud levels. An hour and a half later, mission managers passed up the day's second opportunity as well — saying that although the weather was technically "go" for landing, the conditions were still too unstable to take a chance.
"We’ve been working this pretty hard, as I’m sure you can imagine from our silence down here," capsule communicator Ken Ham told shuttle commander Eileen Collins from Mission Control in Houston. "We just can’t get comfortable with the stability of the situation for this particular opportunity so we are going to officially wave you off for 24 hours."
Later, Collins told Mission Control, "We're going to enjoy another day in orbit, and we'll see you on Earth tomorrow."
Flight director LeRoy Cain said the decision on the second landing opportunity "was a close thing — it wasn't quite good enough." He said Discovery would definitely "land somewhere on Tuesday."
NASA Administrator Mike Griffin said he was comfortable with the one-day delay. "There’s no agony," he told The Associated Press. "We’re going to land one way or another, one place or another, and all we’re talking about is where."
NASA will open up its backup landing sites at Edwards Air Force Base in California and at the White Sands Space Harbor in New Mexico for Tuesday's opportunities. The potential landing times (all Eastern) are 5:07 a.m. and 6:43 a.m. at Kennedy, 8:12 a.m. and 9:47 a.m. at Edwards, and 6:39 a.m. and 8:13 a.m. at White Sands.
Edwards Air Force Base, home to NASA’s Dryden Flight Research Center, is less prone to finicky weather than the shuttle fleet’s Florida home. And even as Kennedy Space Center has taken over as both launch and landing site, the space agency has kept up Edwards as its No. 1 backup.
Of the 111 shuttles that have landed since 1981, 49 came in at Edwards, 61 touched down in Florida, and one landed at New Mexico’s White Sands Missile Range.
NASA prefers to land at Kennedy to avoid the $1 million cost and potential for damage involved in flying the shuttle back to Florida atop a modified Boeing 747.
Cain said Tuesday's weather outlook for Kennedy Space Center was about the same as Monday's. He said the forecast was "very favorable" for Edwards, and somewhat less favorable for White Sands — which has been used only once for a shuttle landing, back in 1982.
If weather or other problems ruled out a Tuesday touchdown, the shuttle had enough supplies to wait until Wednesday.
One more shift
The landing delay marked just one more shift in the schedule for Discovery’s flight to the international space station and back. The shuttle’s launch was delayed for 13 days due to a fuel gauge glitch, and the mission was later extended a day to give more time for transferring supplies to the space station.
Re-entry is considered the most critical phase of Discovery's mission — particularly in the wake of the Columbia tragedy, which forced the 2 1/2-year gap in shuttle flights.
It was during re-entry that the shuttle Columbia disintegrated in February 2003 over Texas, killing all seven astronauts aboard and grounding the shuttle fleet. Investigators concluded that flying foam insulation from the shuttle's external fuel tank cracked a hole in the left wing, allowing superheated atmospheric gases to enter and destroy Columbia from within.
NASA responded to the disaster by making dozens of upgrades in the shuttle and its tank, and also subjecting Discovery to the most exhaustive on-orbit inspection ever. NASA's cameras spotted a flying piece of foam debris — which, fortunately, did not strike the orbiter — as well as two protruding gap fillers that were pulled out during an unprecedented spacewalk. But overall, mission managers said Discovery was one of the "cleanest birds" ever, and they expected a trouble-free re-entry.
Nevertheless, the managers acknowledged that Discovery's descent would be their most anxious hour.
"We are going to be pretty darn happy to get to wheels stop and see this good crew step off Discovery," flight director Paul Hill told reporters in Houston. “We all are going to feel a huge sense of accomplishment having gotten through the last 2 1/2 years and demonstrated that we still know how to do this very difficult and dangerous business.”
Mission's goals
The Discovery mission's goals were to resupply the space station, and to test the inspection and repair techniques that NASA developed in the wake of Columbia's catastrophic breakup.
NASA set up scores of cameras to record Discovery's launch and built a new kind of laser- and camera-equipped inspection boom to survey the shuttle's protective skin while on orbit. During one of the mission's three spacewalks, Discovery astronauts Stephen Robinson and Soichi Noguchi tested patches and fillers that could be used to mend gaps in the shuttle's tiles or reinforced panels.
The pair also repaired one of the station's gyroscopes and replaced another one, bringing the station's four-gyro guidance system to full strength for the first time in three years. During the third spacewalk, they installed a storage platform on the station for future construction jobs — and then Robinson took an unprecedented ride on the station's robotic arm to Discovery's tile-covered belly, where he removed the protruding gap fillers by hand.
Discovery's crew delivered tons of supplies to the station, and for the return trip, they loaded the shuttle with tons of trash and old equipment from the station.
The mission was extended by a day to allow for more transfers, in large part because it may be longer than expected before a space shuttle pays another visit.
Future flights suspended
After Discovery's launch, NASA officials said they were surprised to see that the shuttle's external fuel tank shed more debris than expected, including a pillow-sized, 1-pound (450-gram) piece from an area known as the protuberance air load ramp, which had not been redesigned after the Columbia tragedy.
Mission managers said the problem with the foam debris and the gap fillers would have to be resolved before another shuttle lifts off. In all, deputy shuttle program manager Wayne Hale said 47 items “great or small” would be addressed before the next launch.
Currently, the shuttle Atlantis is due to fly another test mission to the space station no earlier than Sept. 22, but Hale said he didn't consider that "a serious launch date." If Atlantis doesn't lift off by Sept. 24, the next opportunity would be in early November.
The Associated Press contributed to this report.