This story was updated at 7:26 a.m.EDT.
CAPECANAVERAL, Fla.--Despite two opportunities for a morning landing, the spaceshuttle Discovery is still in orbit after cloud cover prevented the orbiterfrom returning to Earth Monday.
Unpredictableweather--pop-up rain showers and a broken cloud deck at approximately 1,000 feet(304 meters) above the Kennedy Space Center's Shuttle Landing Facility--forcedflight controllers to wave-off both of today's two landing opportunities forthe space shuttle Discovery. The landing was originally scheduled for 4:47 a.m.EDT (0847 GMT).
"The only word that describes all this is "unstable"," astronaut KenHam, spacecraft communicator at Mission Control, informed Discovery's crew. "We regret not getting you guys home today."
"You guysmade the right decision," Discovery's STS-114 commander Eileen Collins said. "We'regoing to enjoy another orbit."
The addedday extends an already extended mission for Collins and her six fellowastronauts. Mission controllers lengthenedthe STS-114 flight's stay at the International Space Station (ISS) by one dayto allow more time for cargo transfer between the two vehicles. The astronautswill have spent 14 days in orbit - they were slated for only 12 days - after tomorrow'splanned landing.
LeRoyCain, NASA's ascent/entry flight director for Discovery's STS-114 mission, saidthe orbiter has supplies to stay in orbit until Wednesday. While KSC will stillbe the primary landing target for Tuesday's attempts, alternative landing sitesat Southern California's Edwards Air Force Base and NorthrupStrip at White Sands Missile Range in New Mexico will also be prepared to hosta shuttle arrival, he added.
"We will attemptto land somewhere tomorrow," Cain said after Monday's landing wave-offs.
STS-114 flightcontrollers hope to try for a KSC landing again Tuesday at 5:07 a.m. EDT (0907GMT), but have a total of six opportunities to land tomorrow, shuttle officialssaid. In addition to the initial opening, there is asecond KSC landing opportunity at 6:43 a.m. EDT (10:43 GMT) and two windowseach for Edwards or Northrup, they added.
The weatherforecast at KSC is very similar to what was seen today, whereas the outlook forEdwards is favorable all week, Cain said. Weather predictions for Northrup are not as promising, though that airstrip is Cain'sthird choice for a landing after KSC and Edwards, the flight director said.
Clad intheir orange pressure suits, Collins and pilot James Kelly were prepared toguide the 100-ton Discovery orbiter back to Earth, with STS-114 missionspecialists Stephen Robinson - serving as flight engineer - and Andrew Thomason the flight deck, when the descent was called off. Mission specialists WendyLawrence, Charles Camarda and SoichiNoguchi, an astronaut with the Japanese Aerospace Exploration Agency (JAXA), preparedfor landing in Discovery's middeck.
John Madura, manager of KSC's weatheroffice, said shuttles require a cloud ceiling of 8,000 feet (2,438 meters) toland. Both landing attempts today had cloud ceilings of 1,000 feet (304 meters)or lower, which would have caused visibility problems. NASA prohibits shuttlesfrom flying through rain because of the damage it can cause to the orbiter'sexterior, they added.
"They wantto be able to see the runway," Madura said. "Theydon't want to fly in on instruments."
DuringDiscovery's second landing opportunity Monday, flight controllers reported thatconditions were technically go for landing, but they still had concerns.
"It was aclose thing," Cain said. "I just couldn't get quite comfortable with theoverall day."
Astronautson hand for Discovery's landing said that a wave-off is not necessarily bad,since it gives shuttle crews time to reflect on their mission - especially oneas busy as STS-114.
"We weredelayed four days coming home," said astronaut John Herrington, who served asmission specialist aboard Endeavour during STS-113,NASA's last shuttle to land at KSC. "[The delay] is a chance to sit back andreally take a deep breath to look out the window."
The STS-114astronauts are NASA's first shuttle crew to fly since the loss of the sevenSTS-107 crewmembers aboard the Columbia orbiter, which broke apart over Texason Feb. 1, 2003 during reentry. Columbiawas damaged during launch when a 1.67-pound piece of external tank foam piercedits heat shield, which later allowed hot gases into the orbiter's left wingthat destroyed the vehicle, killing its astronaut crew.
NASA'sspent more than two years and $1.4 billion dollars to prevent such foam lossfrom endangering a shuttle again, only to find a 0.9-piece foam chunk fall fromDiscovery's external tank - but not strike the orbiter - during its July26 launch. At least three other pieces too large for NASA's new safetystandards also separated from Discovery's tank, prompting shuttle officials to suspendfuture shuttle flights until the problem is solved.
Discovery'sexternal tank foam loss cast a cloud over what shuttle officials and STS-114crew tout as a wildly successful spaceflight.
"These 13days have gone by so quickly," Robinson said Sunday. "There've been a lot ofchallenges, but rewarding challenges."
The STS-114astronauts tested a series of new tools developed as a direct response to theColumbia accident, including a laser camera-tipped 50-foot (15-meter) boomthat they attached to Discovery's robotic arm to scan the shuttle's heat shieldfor damage. A suite of wing leading edge sensors, designed to detect impactsand measure temperature during launch, far outlasted their anticipated 36-hourbattery lifetimes and were still functioning as the STS-114 crew prepared forlanding, shuttle officials said.
"We havedefinitely accomplished all our mission objectives," Collins told reportersbefore Monday's landing attempts.
Discovery'screw deliveredabout six tons of food, water, science equipment and spare parts to the ISS -the first shuttle resupply to the station sinceDecember 2002 - and returnedabout three tons of trash, unneeded or broken equipment and more than 10Russian-built Kurs navigation systems used aboardRussian Soyuz and Progress spacecraft to dock at the space station, shuttleofficials said.
Robinsonand Noguchi, STS-114's spacewalking duo, staged three extravehicular activitiesfrom Discovery's airlock to test heat shield repairtechniques, replace a broken ISS gyroscopeand add a spareparts platform to the exterior of the orbital laboratory among other tasks.During their final spacewalk,Robinson also conducted the first-ever repair of the shuttle's belly heatshield when he plucked two gap-fillers jutting out from between the orbiter'sheat-resistant tiles.
Robinsonsaid he and his crewmates were looking forward to getting home and looking overtheir mission's launch video, which relatives told them was amazing.
"We'regoing to get to see this mission from a whole new perspective," he added.
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