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NASA Studies Advanced Shuttle Crew Escape SystemsBy Todd HalvorsonCape Canaveral Bureau Chief posted: 07:00 am ET11 April 2001

http://www.space.com/news/spaceshuttles/shuttle_escape_systems_010410-2.html

CAPE CANAVERAL, Fla. -- It’s an astronaut’s worst nightmare.

An engine failure cripples a space shuttle early in flight, forcing its crew to blast open a sidehatch, hook up to a telescoping pole and bail out into the Atlantic Ocean.

That’s how the shuttle’s $50 million escape system is designed to work -- but in reality, it isabsolutely useless unless an orbiter is flying in a controlled glide above 20,000 feet (6,607meters) -- an unlikely scenario in an explosive emergency.

What’s more, a crew has absolutely no hope of escape when the shuttle’s twin solid-fuel rocket

boosters are firing during the critical first two minutes of flight.

Consequently, independent aerospace experts -- who expect the shuttle fleet to fly at leastanother 20 years -- are urging NASA to develop an advanced crew escape system that willsafeguard astronauts in a wider range of deadly launch failure scenarios.

"The time is past due for the implementation of a more capable crew escape system," theAerospace Safety Advisory Panel said in an annual report released earlier this year.

Chartered by Congress after the 1967 Apollo 1 launch pad fire, the watchdog group said such asystem "will provide the largest potential improvement in crew safety" during what is expected tobe two more decades of shuttle fleet operations.

Senior shuttle program officials, meanwhile, fully recognize the inadequacy of the current systemand are in the midst of reviewing alternatives.

The bailout pole "would not be effective under all failure scenarios -- not even most failurescenarios," NASA shuttle program development manager Elric McHenry told SPACE.com.

"So we have been seriously looking into what it would take to improve our ability to get the crewout in case we had another catastrophic situation."

Added to NASA’s $8 billion fleet after the 1986 Challenger disaster , the current system hinges ona shuttle commander’s ability to gain full control of the ship in the event of an engine failure, aloss of cabin pressure or any other major malfunction in flight.

Here’s how the situation would unfold inside the ship:

First, an astronaut on the shuttle’s mid deck would open a crew cabin vent once the orbiter wasflying stably at 40,000 feet (12,133 meters), a move meant to equalize internal air pressure withthe atmosphere outside the ship.

With both the shuttle's boosters and external fuel tank jettisoned, a commander then would slowthe ship to 225 miles (360 kilometers) per hour before putting the orbiter on autopilot.

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The skipper and other astronauts on the ship’s flight deck then would climb down a ladder to theshuttle's mid deck. There, the shuttle's side hatch -- which is equipped with explosive bolts --would be blown away from the ship, opening up an escape route for the astronauts.

Next, an 8.75-foot (2.65-meter) telescoping pole -- which normally is mounted on the mid-deckceiling -- would be extended through the open hatch. And then, one by one, the astronauts would

hook a parachute harness to the 248-pound (546-kilogram) pole and jump out of the ship andtoward the ocean.

The escape pole plays a critical role: Without it, an astronaut would slam into the shuttle's leftwing or hump-like pods that house orbital maneuvering engines on the tail end of the ship

Theoretically, the bailout would begin at an altitude of about 20,000 feet (6,607 meters) so that allof the astronauts would be out of the ship in time for their parachutes to open up for an oceansplashdown.

Assuming the astronauts all got out of the ship, they likely would hit the water about a mile (1.6kilometers) apart from each other, bobbing along a line that followed the shuttle’s flight path.

The $2 billion spaceship, meanwhile, almost certainly would be destroyed, crashing into theAtlantic at a speed in excess of 200 miles (320 kilometers) per hour. At the same time, helicopterscarrying specially trained Air Force troops would fly out to sea on a search-and-rescue mission.

As for the astronauts, their survival at that point largely would depend on partial pressure suitsroutinely worn during launch and landing.

Another post-Challenger upgrade, the pumpkin-orange suits are equipped with a parachute pack,a built-in life preserver, their own air supply, survival gear and a backpack with a small collapsiblelife raft.

The idea would be to inflate the raft, climb aboard it, and then shoot off flares until search-and-

rescue forces arrived on the scene. The rescuers would be combing a widely scattered area off the coast of  Cape Canaveral for any survivors.

The inescapable problem, however, is this: Most credible launch failure scenarios would make itdifficult, if not impossible, to level the ship’s wings and fly a controlled glide.

So NASA is studying three potential alternatives:

Ejection seats

Shuttle Columbia was equipped with ejection seats for its first few flights. But only a commander and a pilot -- both of whom could be seated on the upper level of the ship’s crew cabin -- wereaboard for those flights.

The system was removed from Columbia when NASA began flying larger crews on shuttlemissions. The reason: NASA could not accommodate astronauts seated on the cabin’s lower level during launch.

Agency engineers, however, have found a way around that problem -- albeit a rather complicatedone.

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As part of a preliminary study delivered to managers last week, engineers outlined plans for anejection seat system that could accommodate four astronauts on the flight deck and two on thelower mid deck.

Significant structural changes would have to be made to the crew cabin to clear the way for themid-deck astronauts, but the general idea is to install a rail system that would guide their rocket-

powered ejection seats out an overhead hatch.

The four flight deck astronauts then would follow:

An extraction system

The same study outlined a rail-guided system that would employ small rocket motors to pullharnessed astronauts out an overhead hatch.

"There would be a small rocket motor that would be fired to pull the crew along that rail and jerkthem away from the vehicle, and away from the plume if there was an explosion going on,"McHenry said.

"It would basically jerk them out of the vehicle and they would be parachuting [to safety]."

Only five astronauts could be accommodated by this system, though, and all would have to beseated on the shuttle’s flight deck.

A detachable crew module

A modified crew cabin that could be jettisoned away from the shuttle is the only apparentalternative for saving an entire seven-member crew.

Attached rocket packs would blast the cabin out away from an explosion, and then parachuteswould be deployed to float the astronauts to a safe landing.

"That’s the most intuitive solution," McHenry said. "But it’s also the most technically intrusive."

Such a system would require major structural modifications to the forward end of the shuttle,weighing down the nose of the orbiter. The shuttle’s wings, consequently, also would have to bemodified "to make it more flyable with all that extra mass in the front," McHenry said.

Thermal shielding also would be a requirement in case a failure cropped up late in flight, exposingthe module to the intense heat experienced during atmospheric reentry.

None of the alternatives would be inexpensive to implement.

A separable crew cabin would cost about $1 billion to design and develop. The other optionswould cost several hundred million dollars.

The investment, however, would give future astronaut crews a fighting chance to survive even aChallenger-like explosion, and if the shuttle fleet is going to fly another 20 years, the odds of another catastrophic failure in flight are fairly high.

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The new study, meanwhile, puts shuttle program managers in a position to move swiftly shouldthe agency, Congress and the Bush administration decide to provide future crews with a morecapable escape system.

"What we are doing is the engineering work that will allow us to decide whether or not it would bein the nation’s best interest to make that major investment," McHenry said.

"It will provide us with the data that will allow us to decide if there are some strategic, long-termcrew safety improvements" that the agency should pursue.