Discovery's Shuttle Astronauts Set for Monday Landing

NASA's space shuttle Discovery is set to land after a 13-day mission on July 16, 2006 CREDIT: NASA.

CAPE CANAVERAL, Fla. - Six NASA astronauts circling the Earth aboard the space shuttle Discovery are ready for their Monday landing after a busy mission to the International Space Station (ISS).

NASA launch and reentry flight director Steve Stitch, said Discovery's STS-121 astronauts, commanded by shuttle flight veteran Steven Lindsey, and their spacecraft are primed to trade orbital flight for a runway here at NASA's Kennedy Space Center (KSC) tomorrow.

"My sense was that they're getting a little bit excited," Stitch said during a mission status briefing. "Tomorrow, they will have their game faces on and they'll be ready to execute the deorbit prep and entry."

Lindsey and his fellow STS-121 astronauts have two opportunities to land KSC's Shuttle Landing Facility Monday, the first at 9:14 a.m. EDT (1314 GMT) and the second at 10:50 a.m. EDT (1250 GMT). The shuttle can also land at KSC, as well as at alternate landing sites in California or New Mexico, on Tuesday and Wednesday, Stitch said.

"If the weather cooperates we'll try to try to get into Kennedy tomorrow," Stitch said.

Rain showers are the only threat for Discovery's return Monday since they may come within a 30-mile (48-kilometer) bubble surrounding NASA's landing facility, Stitch said. Rain can damage the fragile - but vital - heat-resistant tiles that protect Discovery from searing temperatures of reentry, he added.

Discovery's crew is concluding a 13-day mission to the International Space Station (ISS), where the astronauts delivered a massive load of fresh cargo, one new crewmember and made repairs critical to the future construction of the orbital laboratory. NASA's STS-121 mission is agency's second shuttle test flight since the 2003 Columbia accident.

"We're getting ready to come home," Lindsey told NBC News during a series of space-to-ground interviews today.

Discovery's crew spent much of their morning checking their spacecraft's systems to prepare them for a Monday landing. They fired up an auxiliary power unit thought to have a small leak during a series of flight control system checks, but found no issue for tomorrow's planned landing.

Lindsey and Discovery pilot Mark Kelly rehearsed their landing procedures with the aid of a handy computer program and control stick, which the shuttle commander likened to a video game. The STS-121 crew also stowed items into their final landing locations, NASA said.

In addition to Lindsey and Kelly, mission specialists Lisa Nowak, Stephanie Wilson, Piers Sellers and Michael Fossum are returning to Earth aboard Discovery.

Discovery's new tires

Stitch said that Discovery's Earth return will mark the first landing test a Global Positioning Satellite (GPS) navigation system and hardier tires when it touches down on KSC's Runway 33.

"For our heavier missions, the tires that we were using are a little bit marginal for some of our abort cases," Stitch said. "So we've added some additional load bearing capabilities."

Made by Michelin, Discovery's new tires can handle landings with up to a 20 percent load increase and speeds 10 percent faster than normal parameters.

While flight controllers have used a GPS navigation to track space shuttle in orbit, Discovery's landing will be the first time the system is employed during a landing, Stitch said.

The GPS system is an addition to Discovery's orbital TACAN navigation system, and will allow flight controllers to gain experience using it for future shuttle missions.

"It's a little bit of an improved accuracy than our TACAN system," Stitch said of the new system.

NASA officials said TACAN system aboard NASA's Endeavour orbiter has been replaced by the GPS system for its STS-118 flight slated for summer 2007.

"We're going to take it out for a spin on the STS-121 mission," Stitch added.

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