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Space Shuttle Rescue Scenarios

  • By Susan K. Lewis
  • Posted 10.14.08
  • NOVA

On February 1, 2003, as the Space Shuttle Columbia reentered Earth's atmosphere at the end of a two-week mission, it suddenly broke apart in the skies over Texas, instantly killing the five men and two women onboard. In the days following the shocking loss, reporters grilled NASA officials to learn what, if anything, could have been done to save the astronauts. If mission managers had recognized that the shuttle had incurred severe damage during liftoff, could they somehow have brought the crew home safely? 

NASA's initial response was no. Months later, however, the Columbia Accident Investigation Board (CAIB), a group independent of the space agency, requested that NASA engineers take a closer look at the options they might have had for rescuing the astronauts. This time, the findings were different: While the shuttle itself was almost certainly destined for destruction, there was a chance, albeit slim, that the crew could have survived.

The STS-107 crew waves to onlookers as they head to the launchpad. From left to right, at the head of the pack are Pilot William "Willie" McCool and Commander Rick Husband, followed by Mission Specialists Kalpana Chawla and Laurel Clark. Bringing up the rear are Payload Specialist Ilan Ramon (Israel's first astronaut), Payload Commander Michael Anderson, and Mission Specialist David Brown. Enlarge Photo credit: Courtesy NASA

The hypothetical scenarios sketched out below draw upon the CAIB's final report.  Imagine, day by day, how a high-risk, all-out effort to rescue the crew might have unfolded:

January 16, 2003 (Day 1)
Columbia launches from Kennedy Space Center

On a blue-sky morning at 10:39 a.m. the shuttle lifts off on Columbia Mission STS-107. Roughly 80 seconds into the launch, a briefcase-size piece of insulating foam breaks off from the external fuel tank and strikes the underside of Columbia's left wing, but neither astronauts nor personnel in Mission Control are aware of the problem.

Even if they had noticed the small shower of debris from the wing, it's doubtful that flight controllers would have immediately aborted the mission. (In cases of engine failure or other major malfunctions during launch, they can order the shuttle to jettison its solid rocket boosters and external fuel tank, shut down its engines, and glide down to an emergency-landing site in Spain or Morocco. But this problem is far less clear.) By 11 a.m. the shuttle is in orbit high above Earth's atmosphere.

The countdown is flawless and uneventful, and Columbia's liftoff appears trouble-free as well. This will be Columbia's 28th flight and the 113th flight in the Space Shuttle program. Enlarge Photo credit: Courtesy NASA

January 17-19 (Days 2-4)
NASA calls for images of wing

On Flight Day 2, a frame-by-frame analysis of film of the launch reveals the foam striking Columbia's left wing, but no one can tell the exact location of the hit or the extent of damage.

Note: All else from here forward in this narrative is a hypothetical reimagining of events.

Mission managers realize the importance of the debris strike and alert the astronauts. By the end of Flight Day 3, NASA's highest officials have sent out urgent requests for images of Columbia's wing as the shuttle circles the globe, and military and civilian satellites as well as ground-based telescopes come to their aid in an international effort.

Unfortunately, the imaging is inconclusive. So on Flight Day 4 of the mission, NASA scrambles to figure out procedures for an "inspection EVA"—an Extravehicular Activity (more commonly known as a spacewalk). Columbia's astronauts will have to visually inspect the underside of the wing.

January 20 (Day 5)
Spacewalk confirms damage

The crew of Columbia had not anticipated performing any spacewalks during their scientific mission, yet two of the astronauts, Mike Anderson and David Brown, are trained in standard EVA techniques. The inspection spacewalk they now set out to do, while hardly standard, is deemed relatively low-risk, with a high prospect of success.

Anderson and Brown suit up for a two-hour spacewalk and egress the vehicle through the airlock. They move onto the payload bay door on the shuttle's port side. In its folded-open position, this door hovers just four feet above the shuttle's left wing. The astronauts crawl along the door, looking down at the wing, but from their perch they can't see the site of the foam hit, which is on the wing's underside. So Anderson turns himself into a human ladder—grasping the outer edge of the door with his gloved hands and extending his lower body. One of his boots is wrapped in towels, so that if he needs to step down onto the wing for stability he is less likely to cause more damage. Once Anderson is steady, Brown climbs down Anderson's body to peer over the wing's edge and inspect the underside.

This NASA drawing shows how Anderson and Brown would have maneuvered themselves for the inspection spacewalk. Enlarge Photo credit: Courtesy NASA

What David Brown sees confirms NASA's and the astronauts' worst fears—there is a six-inch diameter hole in the leading edge of the wing, breaking through crucial thermal protection that keeps the shuttle from burning up during reentry. The damage is potentially catastrophic.

January 20 (Day 5)
Crew begins conserving "consumables"

Columbia had originally set off for a 16-day mission. Now the number of days it will remain in orbit, and much else, lie in question. The crew is instructed to power down to about a third the energy use of normal operations. They shut off all equipment for food preparation and science experiments as well as the majority of cameras and computers. One General Purpose Computer (GPC) is left fully powered for vehicle control, and another GPC runs at 25 percent for systems monitoring.

The crew should have enough food to last them more than 30 days. Their oxygen supply is more worrisome. Oxygen is needed not only for breathing but also for the remaining fuel cells that are generating electricity and also providing the crew with drinking water. NASA technicians estimate that oxygen stores will last only through Flight Day 31.

The most critical consumable, however, is lithium hydroxide, the chemical that scrubs carbon dioxide from the crew's cabin. Buildup of carbon dioxide will eventually make the cabin's atmosphere toxic. The astronauts are directed to limit respiration as much as possible. They stop exercising and become hyperaware of every unnecessary physical movement. They euthanize the animals in the Spacelab. And, aided by medication, they begin sleeping 12-hour shifts. With these measures, Columbia's crew should be able to survive through Flight Day 30.

The deadline is now set: The astronauts must somehow be saved by the morning of Flight Day 31, February 15.

Astronaut Michael Anderson in the Spacelab module during the actual mission. If the rescue mission imagined here had taken place, the lab's equipment would have been powered down on Flight Day 5. Enlarge Photo credit: Courtesy NASA

January 20 (Day 5)
NASA looks at rescue and repair options

Mission Control recognizes that Columbia cannot be brought home as is; they have calculated that the damage to her left wing, as reported by the astronauts, puts the shuttle at too great a risk of breaking apart upon reentering Earth's atmosphere. So what can be done? Can the shuttle make its way to the International Space Station (ISS) to undergo repairs or transfer the crew? This scenario is bandied about by bloggers on the Internet, who by now have heard of Columbia's distress, but NASA knows it isn't feasible—Columbia simply doesn't have enough fuel to propel itself to the station.

For the next three weeks, NASA will pursue, in parallel, two alternate tacks for saving the astronauts: 1) Rescuing the crew with Columbia's sister ship Atlantis, and 2) Attempting makeshift, in-orbit repairs to Columbia's left wing, followed by a high-risk reentry. One or the other option is likely to prove unmanageable, the agency believes, but hopefully not both.

January 20-February 10 (Days 5-26)
Atlantis prepped for rescue mission

Atlantis had been scheduled to depart on a mission to the ISS six weeks from January 20. Can NASA prepare the shuttle for liftoff in half the time, by February 10? This is the date mission managers target in order to allow a reasonable window for the launch, which could be delayed by bad weather, and the rendezvous with Columbia before the crew's lithium hydroxide runs out on February 15.

It generally takes three weeks to prepare a space shuttle for liftoff once it arrives at the launchpad. On January 20, Atlantis isn't even at the launch site but rather at Kennedy Space Center's separate Orbiter Processing Facility. Atlantis's main engines, though, are already installed. And at the nearby Vehicle Assembly Building, the final stop on the way to the launchpad, the solid rocket boosters are already mated with the external fuel tank.

Columbia's sister ship, Atlantis. In this picture, taken at the Vehicle Assembly Building, the winged orbiter is already attached to the massive external fuel tank and solid rocket boosters needed for launch. Enlarge Photo credit: Courtesy NASA/Kim Shiflet

Still, countless tasks and tests remain to ensure that the world's most complicated vehicle will be ready for spaceflight. Three shifts of engineers and support staff work around the clock, seven days a week.

January 20-January 25 (Days 5-10)
Crew attempts to repair wing

As Atlantis is rushed to the launchpad, Columbia's astronauts, guided by a special team at Mission Control, begin to execute a repair plan. Columbia has no repair kit or tools specific to the task. Everything must be improvised.

The objective is not to restore the wing to a pristine state. The astronauts just need to jury-rig a repair that will keep superheated gases from entering and destroying the wing upon reentry. After several days of intense brainstorming, which includes teams on the ground testing possible maneuvers in a virtual reality lab, Columbia's astronauts brace themselves for the endeavor. The ground team has deemed the repair "highly difficult, with a moderate risk of danger to the crew and only a low chance of success."

Rather than rely on a human ladder, as in the inspection spacewalk, Anderson and Brown move an actual ladder from inside the shuttle to the repair site. They secure the ladder to the payload bay door, suspending it down toward the damaged wing.

For the hypothetical repair work, Anderson and Brown use a ladder taken from the mid-deck of the crew cabin. In this illustration, the ladder hangs down from the edge of the open payload bay door, which lies four feet above the damaged wing. Enlarge Photo credit: Courtesy NASA

Meanwhile, their fellow crew members scour the cabin and Spacelab for small instruments, canisters, and other objects made of heavy metals. Titanium is best, because it can withstand heat upwards of 3,000 F, but stainless steel and even aluminum will do. It's hoped that this hodge-podge of metals, stuffed into a bag inserted through the hole in the wing, will provide a makeshift thermal barrier.

Anderson and Brown transport the scavenged metal to the repair site. Piece by piece, they put the metal through the hole and into the stowage bag inside the wing's cavity. The bag of metal alone won't be enough to fill the large cavity. So the astronauts also insert three empty Contingency Water Containers (CWCs), and, with a hose run from the airlock water supply, they fill and expand the CWCs with water, which quickly turns to ice. They also have on hand insulation blankets to use as a final packing material. The blankets will likely burn up quickly at the start of reentry, but they might at least hold the bag of metal in place a bit longer, as well as help make the patched area smoother. Any roughness will increase turbulence and thus heat to the wing.

As a final measure, the astronauts spray water from the hose to coat the wing in ice. This icy shell should gradually reduce the overall temperature of the structure, perhaps buying a little more time during reentry.

January 25 (Day 10)
High-risk reentry plan abandoned

Even if Columbia manages to stay intact as it pierces Earth's atmosphere, NASA's engineers expect a wing collapse near the runway or a landing system failure. Columbia's crew is prepared to eject with parachutes once they reach an altitude of 35,000 feet and send the shuttle, on autopilot, to crash over an uninhabited region. But analysis of the repair work now clearly shows that the wing will disintegrate during reentry, so NASA abandons the perilous plan altogether.

Despite Anderson and Brown's concerted efforts to mend the wing, too many uncertainties remain to attempt to bring the astronauts home in Columbia. Even if the ship is made lighter by jettisoning cargo, and even if the shuttle descends in a modified position to lesson drag and heat on the damaged area, the risk of the wing and the entire shuttle coming apart upon reentry is too severe.

February 10 (Day 26)
Atlantis ready to launch

Fortunately, the round-the-clock effort to prepare Atlantis has gone off without a hitch, and the weather forecast looks good. Three days before the anticipated launch, Columbia's crew spends some of its dwindling fuel supply to propel the crippled shuttle to a slightly higher orbit, a position that increases the likelihood of a successful rendezvous.

On the night of February 10th, at 9:40 p.m., Atlantis lifts off into a dark, cloudless sky, with the nation and much of the world watching. Atlantis's crew is barebones to leave room in the rescue shuttle for Columbia's seven astronauts. Only a commander, a pilot, and two of NASA's most trusted and experienced spacewalkers are on board. For a normal mission, the spacewalkers would have practiced their EVA protocols for almost a year; for the extraordinary rescue mission ahead, they have trained just two weeks.

On Flight Day 26 in our scenario, Atlantis launches to retrieve the astronauts, who have dwindling supplies of life-sustaining oxygen and lithium hydroxide. Here, an actual launch of Atlantis. Enlarge Photo credit: Courtesy NASA

February 13 (Day 29)
Rendezvous of Atlantis with Columbia

By February 13th, the men and women on board Columbia are beginning to feel the effects of carbon dioxide buildup in the cabin air—dizziness, headaches, fatigue. Their supply of lithium hydroxide, the chemical that clears out carbon dioxide, is almost depleted. But their spirits revive as Atlantis comes into view through the portholes.

Columbia's pilot, William "Willie" McCool, turns the shuttle to a top-down position, with its payload bay open toward Earth as it orbits. Atlantis eases up and "stops" directly below and perpendicular to Columbia, also with its payload bay open, so that the open bays face each other. NASA has used a similar approach in the past, when the shuttle has rendezvoused with Russia's Mir spacecraft. But never before have two shuttles orbited in such close proximity—just 20 to 30 feet from one another—for an extended time. Transferring Columbia's crew may take eight or nine hours.

February 13 (Day 29)
Rescue spacewalk

The first priority for Atlantis's two spacewalkers is to take an emergency supply of lithium hydroxide to Columbia. They extend a long, retractable pole to bridge the gap between the shuttles and then move, hand over hand, along the pole to cross over into Columbia's bay, where Anderson and Brown, wearing Columbia's only two spacewalking (EVA) suits, are stationed to help with the operation. Atlantis's rescuers also carry over two additional EVA suits, which they leave in Columbia's airlock.

After helping Anderson and Brown make their way to Atlantis, the rescuers install a laser reflector on Columbia. A laser beamed from Atlantis's Trajectory Control System will help the pilots of the two shuttles maintain proximity.

To help keep the two shuttles together, the pilots would focus on a laser beam, seen here as a faint line extending upwards from Atlantis. To the left of this beam, two astronauts traverse along a pole extended to bridge the ships. Enlarge Photo credit: Courtesy NASA

By now, two more of Columbia's crew, Laurel Clark and Ilan Ramon, have suited up and are ready for transfer. Neither has ever performed a spacewalk before, so the 20-foot trip is daunting. Once they are safely inside Atlantis, it's Mission Specialist Kalpana Chawla's turn to be brought over, leaving only Pilot McCool and Commander Rick Husband on Columbia. Before abandoning their ship, McCool and Husband shift control of Columbia to the ground-based Mission Control Center, which will later direct the damaged shuttle to deorbit and burn up over the South Pacific.

In an actual rescue, the astronauts would have had to make their way across a gap of roughly 20 to 30 feet. Enlarge Photo credit: Courtesy NASA

February 15 (Day 31)
Safe return

On the morning of February 15, the seven crew members of Columbia STS-107 return to Earth. The ride home—lying on their backs, strapped to the floor on the lower deck of Atlantis—is unusual but without mishap. The astronauts are exhausted from four harrowing weeks, but they are alive—the survivors of a spectacular rescue mission in space.

Could it have happened?

How plausible is the above Hollywood-style scenario? Clearly, the rescue operations as imagined were intricate and dangerous, with dozens of what NASA calls mission "firsts." All of these unprecedented steps—rushing Atlantis to the launchpad, keeping two shuttles together in orbit for 10 hours, transferring novice spacewalkers from ship to ship—had potential pitfalls.

If such a mission had actually taken place, each step would have had to happen like clockwork for the mission to succeed. NASA would have had to act swiftly to recognize the threat of the debris strike, then formulate and execute an extraordinary plan. The limited supplies of lithium hydroxide and oxygen on Columbia would have made quick action imperative.

Perhaps most importantly, NASA would have had to launch a second shuttle, carrying four more astronauts, without fully understanding the cause of the first debris strike—with the chilling possibility that Atlantis, too, might suffer damage on liftoff and be crippled in space. The CAIB concluded that the ultimate decision to launch, most likely, would rest with the President.

Would NASA have pushed for Atlantis's launch, and would President Bush have authorized it? Spaceflight is an inherently risky and heroic endeavor, and it's the American way, if not human nature itself, to try everything possible to save lives in danger. Columbia had seven astronauts aboard, including a guest astronaut from Israel. Few within NASA, and perhaps in the world at large, would have been surprised if NASA, with government approval, had gone for it. And considering NASA's accomplishments in space—even returning the crew of the severely stricken Apollo 13 safely to Earth—they might just have pulled it off.

The seven men and women of Columbia never had the chance to see this photo taken during their flight. It was on a roll of unprocessed film that searchers recovered from shuttle debris on the ground after the disaster. Enlarge Photo credit: Courtesy NASA

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