Logo of Shuttle Radar Topography Mission. Photo: NASA

After much haggling, NASA and the U.S. Air Force have settled on a plan that will allow space shuttle Endeavour to launch this month on a mission to map the Earth's surface.

Officials announced Thursday that Endeavour has been given the green light to lift off from KSC's pad 39A at 12:47 p.m. EST (1747 GMT) on January 31.

"We had to go ahead and bargain to get our time," shuttle skipper Kevin Kregel told reporters Thursday afternoon during a pause in training at the launch pad.

For the past few weeks, the space agency had been negotiating with the military-run Eastern Range to permit the shuttle launch to be scheduled.

The Range, which provides critical communications, tracking and safety services for all Space Coast launches and shuttle landings, was slated to close in mid-February for upgrades.

Such a blackout would have prohibited Endeavour from launching in late January and still being able to land at Kennedy Space Center after its 11-day flight.

But under the new plan, the shuttle will have launch attempts on January 31 and February 1.

If Endeavour is still on the ground, NASA would have to wait until February 9 so that two previously scheduled commercial rocket launches can be flown from nearby Cape Canaveral Air Station, said Air Force spokesman Lt. Col. Tony Cherney.

The Range upgrade period is now slated for February 28 through March 17.

In the comprise, NASA gave up its Range reservation for the planned March 16 launch of space shuttle Atlantis to the International Space Station. Preparations for that mission are running behind schedule and it is believed the shuttle won't be ready for launch until April 13.

Meanwhile, the planned March 1 launch of a Titan 4B rocket and Defense Support Program satellite from the air station will either move up to a yet-unpicked date between February 9 and 22, or wait until after March 23, Cherney said.

The astronauts after arriving at Kennedy Space Center on Tuesday. Photo: NASA

Today, the shuttle astronauts will wrap up their three-day practice countdown and emergency training at KSC with a launch day dress rehearsal.

The six international crewmembers will be awakened at about 6:45 a.m. EST, have breakfast, put on their spacesuits and head for the launch pad just before 8 a.m. EST.

Once at the oceanside pad, the astronauts will be strapped aboard Endeavour for the final three hours of the mock countdown. The test will conclude with a simulated ignition and shutdown of the shuttle's three main engines at about 11 a.m. EST.

NASA is also using the practice countdown to ensure the shuttle, ground systems and computer networks are Y2K compliant.

Endeavour's flight, the first human spaceflight of the new millennium, will produce a high-resolution, three-dimensional topographic map of Earth's surface.

"In 11 days, we can get about every land mass on the Earth between the two arctic circles," Kregel said.

Currently, only two or three percent of the planet has been mapped with such detail, Kregel pointed out. Endeavour's flight aims at mapping 80 percent.

Artist's concept of Endeavour and the Shuttle Radar Topography Mission payload working in orbit. Photo: NASA

After reaching an orbit about 126 nautical miles above Earth, the crew will extend a 200-foot long antenna mast from the shuttle's payload bay. The boom will become the largest fixed structure flown in space, NASA says.

The mast and another radar antenna that fills the payload bay will work in concert to map the planet in daylight or darkness, clear or cloudy skies.

In order to complete the work, Endeavour will need to make 159 consecutive mapping orbits around Earth.

"Any orbit that we miss getting data is a piece of the Earth that we can't get on this mission," Kregel said.

The new map should give authorities better information for managing Earth's resources, forest preservation and even the placement of cellular telephone towers.

"With every improvement of resolution of our knowledge of the surface the Earth, we will get a corresponding improvement in our ability to manage our environment," said Endeavour astronaut Janice Voss.

The Shuttle Radar Topography Mission is a joint effort between NASA and the U.S. National Imagery and Mapping Agency, with German and Italian participation.