CAPE CANAVERAL, Fla. -- A plan for increasing the odds that a shuttle crew could survive an in-flight emergency is taking shape at NASA, but nothing on the drawing board ensures that any astronaut will be guaranteed a safe round trip aboard the agency's orbiter fleet -- now or in the future.

As the space agency works through this return to flight period following the loss of shuttle Columbia, the immediate goal of improving safety will center on fixing the problems that caused the Feb. 1 disaster in the first place.

Then the emphasis will be on continuing to improve the shuttle fleet's reliability through system upgrades so that if difficulties arise, landing the orbiter with the crew still safely aboard would still be possible.

New technology in the way of improved cockpit displays, engine health monitoring systems and replacing hydraulic systems with electric motors all are examples of modifications NASA has previously identified to extend the shuttle's lifetime another decade or so.

Already equipped with the so-called "glass cockpit," the modern computer screens the astronauts watch during the most critical mission phases are to be further enhanced to display more information about where the crew is and what's happening around them -- something pilots call "situational awareness."

Another safety initiative already in the planning stages involves an upgrade to the computer system that monitors and controls each of the three liquid-fueled Rocketdyne main engines that lift the shuttles into orbit. The new system will be better equipped to handle emergencies with the powerplants and pass along more in-depth information to the crew and Mission Control.

One of the biggest changes to the shuttle being considered is to remove the hydraulic system that provides pressurized fluid to move such things as the orbiter's wing flaps and replace it with electric motors capable of doing the same job.

Many believe such technology has matured to the point where the electric motors are ready for spaceflight, a move that would eliminate the shuttle's auxiliary power units. These are high-speed devices powered by toxic hydrazine that provides the mechanical energy necessary for pressurizing the hydraulic system.

Later, in the 2012 timeframe, NASA hopes to be operating the Orbital Space Plane (OSP) as a means for ferrying up to four astronauts between Earth and the International Space Station (ISS). Before that, by 2010, NASA wants to post an OSP at the ISS as a lifeboat to replace the Russian Soyuz.

The OSP would be launched from Cape Canaveral atop an expendable rocket, such as the Delta 4 or Atlas 5, and return to Earth either by gliding to a runway landing or parachuting to the surface, depending on if the OSP is winged or capsule-shaped.

When the OSP is ready to serve as a crew transfer vehicle, the number of astronauts flying aboard the space shuttle can be reduced from as many as seven to as few as two.

In this way NASA can continue to rely on the shuttle's large round-trip cargo-carrying capability to service the ISS through 2020, while at the same time introduce improved crew escape features -- such as ejection seats -- for the smaller shuttle crew.

"One of the biggest hang ups we've had on crew escape in the past has been the size of the crew," O'Connor said.

When shuttle Columbia first launched on April 12, 1981, commander John Young and pilot Robert Crippen were the only crewmembers aboard. They wore pressure suits and sat in ejection seats based on the SR-71 supersonic spy plane.

If anything went wrong during the first few moments of flight, the crew could eject. After the solid rocket boosters separated, any emergency would result in the crew attempting a landing back at Kennedy Space Center, overseas in Europe, or in California or New Mexico after nearly circling the planet.

The next three shuttle missions also featured two-man crews and the availability of ejection seats. But for STS-5 the crew size increased to four. So while commander Vance Brand and pilot Robert Overmyer sat in Columbia's ejection seats, the seats were disabled so as not to leave behind mission specialists Joe Allen and Bill Lenoir.

Columbia's ejection seats were removed during its first overhaul back at the Palmdale, Calif., factory where it was assembled. Challenger, Discovery, Atlantis and Endeavour never were equipped with ejection seats.

It was also on STS-5 that shuttle astronauts stopped wearing pressure suits -- the assumption being that in any emergency the shuttle would "escape" the situation by landing.

The 1986 Challenger disaster prompted a change in operations. The crew began wearing pressure suits again and an escape pole was added to the crew cabin in case the astronauts were forced to bailout. The extended pole is supposed to prevent any crewmember from striking the wing on the way down.

"Those were great improvements over what we had before, which was fundamentally nothing," said O'Connor, who was directly involved in the post-Challenger safety upgrades made available for the crews.

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