Dye downplayed the late decision and said project managers reached a consensus, not in haste, but as part of the evolutionary process of a shuttle mission.
"We continually review our missions," Dye said. "We decided it was a good idea to preserve the mast -- to keep the capability to bring the mast in. This is a device which weve never deployed before."
In an emergency, Endeavours crew can jettison the mast.
Dye added that due to the power-intensive nature of the radar that will be used, the shuttle wont have enough power aboard to extend the flight for further mapping.
The most critical moments of the mission are deployment and recovery of the 200-foot metal and plastic antenna mast. The item has never flown in space before and once extended, will be the longest rigid structure deployed in space to date.
Astronauts Janet Kavandi and Gerhard Thiele are trained to perform a spacewalk to assist in deploying or recovering the mast if a problem develops. This will be Thiele's first space flight.
Endeavours crew will spend about nine days mapping 80 percent of the Earths land area with radar to produce improved 3-D maps for commercial, military and intelligence gathering purposes. NASA sponsors the mission along with the Defense Departments National Imagery and Mapping Agency, the German Aerospace Center and the Italian Space Agency.
Project scientists from NASAs Jet Propulsion Laboratory (JPL) in Pasadena, California tried to stay optimistic about the shortened mission.
"Wed been planning for a 10-day mission for complete coverage of the continents, but well be about 16 orbits short of that," said Dr. Earnest Paylor, radar mission project scientist.
JPL project scientist Dr. Michael Kobrick said he is looking at alternatives to gather the data lost under the new flight plan.
"I am hopeful that if the mast works well and behaves and if we husband our resources, we can get that 10th day," he said. "I dont think its completely ruled out and Ill be lobbying in that direction."
Kobrick added scientists would look at altering the orbit or additional shuttle maneuvering to capture the lost data.
While no definite plans have been made to fly the radar payload a second time to gather more images, Kobrick said he would support another flight.
"The payload can fly again and well be ready," he said.
The decision to shorten the mapping operation is the latest setback in Endeavours journey toward the launch pad.
Originally set to launch in September, Endeavours mission was delayed while technicians completed wiring inspections and repairs of the orbiter fleet. An electrical short knocked out two of three engine controllers aboard Columbia during its July launch.
NASAs decision to launch Discovery on a mission to rescue the ailing
ahead of schedule pushed the radar-mapping mission even further back.Though mission managers are trying to hold to the current date, the launch might be pushed back as engineers do a paperwork drill to check if the more than 25,000 thermal tiles on the belly of Endeavour are attached properly.
Discovery lost one of the tiles that protect it from the extreme heat of reentry when it returned to Earth on December 27. Records show the tile was improperly installed.
The six-person crew consists of commander Kevin Kregel; pilot Dom Gorie; payload commander Janice Voss, along with mission specialists Janet Kavandi, Mamoru Mohri of the Japanese space agency and Gerhard Thiele of the European Space Agency.
Kregel called the shortened mission "nothing new. It's all about margin. We want to save the mast and bring it in for analysis," he said. "We'll get as much data as we can to bring back. Then we'll retract the mast and get ready to land."
Once the crew deploys the mast at about five hours into the flight, the crew will spend another seven hours testing the radar equipment. The crew then splits into two shifts to gather data around the clock.
The crew will use a technique called
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