As a boy growing up in Burlington, Iowa, Jim Kelly dreamed of becoming an astronaut. At night, he would often crack open his bedroom window and listen to the roar of jets flying low just beyond the cornfields.
Mr. Kelly does not plan to open a window, but he does plan to listen Aug. 8 for the roar of space shuttle Discovery's twin engines as they hit a powerful de-orbit burn, untethering the ship from orbit speed and sending pilot Kelly and six fellow astronauts hurtling home.
Given the disastrous ending of the previous landing attempt when the shuttle Columbia broke apart over Texas in January 2003, killing all aboard, this homecoming was viewed as far from routine. Its success can restore the nation's faith in NASA, an agency hobbled by budget woes and whispers of obsolescence. Its failure, as Apollo 13 flight director Gene Kranz famously said, is not an option.
But bringing Discovery home safely is a feat involving much more than NASA, said former shuttle pilot Jeff Ashby, who serves at the Air Force Space Command in Colorado Springs as a liaison between the Defense Department and the space agency: "It's a huge team effort."
The landing operation alone requires the technical savvy of thousands of military personnel, civilian contractors, and civil servants manning stations around the globe, and the skill and courage of astronauts Jim Kelly, Steve Robinson, Andy Thomas, Wendy Lawrence, Charlie Camarda, Eileen Collins, and Soichi Noguchi-the seven souls who dared to try again. Here's an inside look at how those final moments must fly:
"You are GO for the de-orbit burn."
That is the command from Mission Control, at Johnson Space Center, Houston, that Discovery's crew wants to hear. The two- to three-minute burn will at first propel Discovery through space tail-first. Then, as the craft streaks toward Earth at 17,000 miles per hour, Mr. Kelly will turn the craft head-first and belly-up, aiming Discovery's heat-deflecting underside toward the inferno of reentry.
The health of the ship's belly is critical: In an unprecedented maneuver on Aug. 3, Mr. Robinson spacewalked underneath Discovery and, using only his gloved hands, plucked two pieces of loose fabric from between its thermal tiles. He put them in a trash bag he'd brought along. NASA thought the ceramic-fiber "gap-fillers" could cause potentially disastrous overheating, or tear loose and become dangerous debris.
Inside Cheyenne Mountain, Colorado Springs, Colo.:
Behind a pair of 25-ton steel blast doors deep inside Cheyenne Mountain, the Air Force's 1st Space Control Squadron wants to keep Discovery clear of the swirling mix of space debris and live satellites that now orbit Earth.
During shuttle missions, the squadron uses a global network of 21 radar and telescope arrays called the Space Surveillance Network (SSN) to track more than 13,400 manmade objects-from defunct satellites and random hunks of metal to bus-sized spent rocket bodies and four-inch bolts. Around the clock, the 1st Space Control Squadron relays "conjunction data"-that's space-talk for "information about things that might hit each other"-to Mission Control in Houston. It's up to Houston, said Space Protection Officer Dave Ward, whether to tell the shuttle to take evasive action.
In January, high over Antartica, a southbound fragment of a Chinese rocket that exploded five years ago collided with the engine from a Thor rocket launched in 1974. Manned-flight collisions with objects of significant size are extremely rare. But in 1999, the shuttle Discovery returned to Earth with evidence that small manmade objects had hit it at least 10 times.
Debris has been of special concern since the 2003 disaster. On launch, Discovery shed a small piece of thermal tile, as well as a large piece of foam from its external tank (ET), the same type of material blamed for the loss of Columbia. About 20 seconds later, a smaller piece of foam separated from Discovery's ET. It apparently struck the orbiter's right wing, though NASA does not believe the impact caused damage.
During the Columbia mission, sparse SSN track-data provided the 1st Space Control Squadron with early, sketchy signs that the shuttle had shed debris. It turned out to be a piece of the leading edge of Columbia's left wing, damage that investigators later determined was a major factor in the crash. But during the flight, "we couldn't confirm it was an actual piece," Mr. Ward said. "Unfortunately, after the mission we were able to go in and find additional data from our [SSN] sensors never reported to us." Now, a software upgrade forces all SSN track-data back to Cheyenne Mountain, ensuring that 1st Space Control can help NASA clear Discovery's way home.
About 30 minutes after de-orbit burn, at 400,000 feet above Earth, the ship will punch through the skin of the atmosphere and the air around Discovery's nose will erupt into orange-yellow flame.
Out the front window, the crew "will see fire and start to get a sense of speed," said Jeff Ashby, the former shuttle pilot, and begin to see details on the ground rushing by. As the ship superheats the air with its passage, a "plasma trail" will envelope the craft like a teardrop and first-time space travelers like Soichi Noguchi will likely marvel at swirl patterns visible in the plasma through the craft's port and starboard windows.
At the 22nd Space Operations Squadron (SOPS), Shriever AFB, Colo:
Only 15 antennas sprinkled around the globe serve the 170 U.S.-controlled satellites that spin some 22,000 miles above it. Collectively, the antennas are called the Air Force Satellite Control Network (AFSCN). The job of the 22nd Space Operations Squadron, in plain language, is to divvy up antenna time for satellite operators-scientists, weather guessers, cable companies, spies-who need to maneuver and "talk" to their orbiting birds.
A NASA shuttle in orbit, said 22nd SOPS Commander Lt. Colonel Michael Moran, is priority one. During shuttle descents, the AFSCN becomes very important to Mission Control. While in orbit and docked at the International Space Station, the shuttle communicates with Houston using its own onboard antenna. But prior to heading home, Discovery's crew, following standard procedure, will stow that antenna, leaving NASA to rely on the AFSCN and other military assets to allow commanding of the orbiter and the downloading of "telemetry," data from the ship's sensors and instrumentation.
When Columbia disintegrated over Texas, Mr. Moran was working on another part of Shriever and helped to collect data tapes and satellite downlinks to aid NASA's investigation. In the run-up to the Discovery mission, he and his team of 350 have trained as though prepping for the Super Bowl of space.
"We spent a tremendous amount of time [on] individual training and systems training," Mr. Moran said. "We ran numerous data-flow checks from NASA to every single ground station."
The training extended to every one of 20 to 30 operators AT EACH of the squadron's remote tracking stations in Greenland, the Indian Ocean, Hawaii, Guam, California, and the UK, with intensive "proficiency checks" during the six months prior to launch.
"Everything was checked and double-checked," Mr. Moran said.
Mr. Moran laughed at his own understatement. "Whatever number of checks you're thinking we did, add a zero."
As the shuttle hurtles past 250,000 feet, Earth's surface details will crystallize before the astronauts' eyes: coral reefs, minor cities, the shuttle runway at Kennedy Space Center. "Visually what struck me most were the thunderstorms," said Jeff Ashby, the former shuttle pilot. Sometimes, he said, he could see lightning flashing atop towers of dark, rolling clouds.
Passing 248,000 feet, Mr. Kelly will crank Discovery into an almost 80-degree bank, the first of four turns designed to dissipate speed as the ship approaches Florida. Soon after, Discovery and her crew will burst out of orbital darkness into the sunlight.
Kennedy Space Center, Fla:
For most of Discovery's approach, a tiny swarm of aircraft will fly high over the Atlantic to sniff the weather, and low over the Shuttle Landing Facility at Kennedy Space Center (KSC) to check final approach conditions. A NASA T-38, or possibly a pair of the sleek, high-speed jets, will perform weather reconnaissance to a range of 125 miles surrounding the shuttle runway.
Meanwhile, a NASA Gulfstream II, the shuttle-training aircraft, will make repeated approaches to both ends of the KSC runway to see how the aircraft handles on final approach. Contract air traffic controllers in KSC Tower, a spanking new, $3.3 million spire that opened in July, will relay the data to Mission Control for final runway selection.
At any point during Discovery's approach, Mission Control lead flight director Paul Hill could declare a "contingency," sending the shuttle to an alternate landing site-Edwards AFB, California, or White Sands Missile Range in New Mexico-or activate emergency teams in the event of catastrophic malfunction.
Passing 225,000 feet, Discovery will execute the second of four banks, continuing to bleed speed as it morphs gradually from spaceship to aircraft.
Remote Operations Center (ROC), 45th Space Wing, Cape Canaveral, Fla:
Thirteen minutes prior to landing, the Air Force's 45th Space Wing Range Operations Control Center (ROCC)-pronounced "Rock"-will acquire Discovery on its D-BRITE radar system. But that will be only the ROCC's first visual contact with the shuttle. Five hours prior to scheduled landing, about 500 Wing personnel will have manned up the ROCC's high-tech consoles to monitor radar and telemetry data and "push it" to KSC and Mission Control.
As Wing commander, Col. Mark Owen-he'll be a brigadier general soon; the Air Force just hasn't pinned on his star yet-is director of a huge hunk of real estate known as the Eastern Range, a military operations zone that extends more than 10,000 miles from the Florida mainland to the Indian Ocean. Officers in the ROCC will ensure that the 40-nautical-mile bubble of the Range that surrounds KSC is sterilized of all surface ships and aircraft, except for the T-38s and Gulfstream II.
If Mission Control selects KSC for landing, the ROCC will track Discovery as she maneuvers for final approach. In Columbia's wake, "there's definitely a certain amount of sweaty palms and elevated heart rate associated with this mission," Mr. Owen said. It's not that there's additional risk; in fact, he believes NASA learned from Columbia, making this mission safer. "That said, though, we've all been sitting on the edge of our seats waiting for this [landing]. We've been through all the scenarios. We've been trained, and on game day, we want to be as flawless as any competitor would want to be."
Still hurtling toward Earth at 10,000 feet per minute, Mr. Kelly will execute two more banks to decrease speed, slowing to the speed of sound-about 740 miles per hour-about five minutes before landing. If the crew follows normal procedures, shuttle Commander Eileen Collins will then take the controls and guide Discovery to the 15,000-foot shuttle runway at KSC.
Will she be thinking about Columbia? Will any of the crew?
"I've thought about that," astronaut Jeff Ashby said. "I flew with memories of the Challenger crew. I'm sure thoughts of [the Columbia crew] have come up."
But Mr. Ashby said during re-entry the atmosphere on the flight deck is very businesslike. He thinks the Discovery astronauts will be focused on taking care of business. That, and on the excitement of coming home.