Since the 1988 return to flight of Discovery, the space agency hasn't paid much attention to improving crew escape options, concentrating instead on making the shuttle more reliable so such emergency measures wouldn't be necessary.

As it became clear that NASA would be forced to continue to rely on the shuttle for another 20 years, the idea of adding new crew escape capabilities gained attention -- specifically by the Aerospace Safety Advisory Panel (ASAP).

Established by Congress following the 1967 Apollo 1 fire, the ASAP is made up of independent safety experts who produce an annual report detailing what the space agency is doing and right and wrong in safely conducting its operations.

During the past three years the ASAP has called upon NASA in increasingly direct language to essentially make up its mind on whether or not the agency was going to add new crew escape capability to the shuttle or accept the inherent risk as it is.

But that doesn't necessarily mean NASA must install a new crew escape system that would ensure survivability in any scenario someone could dream up, ASAP panel member Bob Sieck told SPACE.com.

For example, a completely self-contained escape pod could be built to replace the current shuttle's crew cabin. But it would cost so much money, take years to design and install, and reduce the shuttle's cargo carrying capability to an inconsequential amount that such a system makes no sense.

"The essence of our finding and recommendation was for NASA to state what its policy is regarding crew escape and whatever NASA chooses to do, so be it," said Sieck, who is a former shuttle launch director at Kennedy Space Center.

"If you're going to live with the current system for the life of the program then state that accordingly, and the rationale for it, and then get on with the rest of the program," Sieck said. "But if you want to improve what you have, there are alternatives out there."

Methods to improve a crew's chances of living through a mission have been discussed in testimony before the Columbia Accident Investigation Board (CAIB), who in their final report due out in late July will make specific recommendations on what needs to be fixed before shuttle missions can resume.

Those repairs likely won't take a long time to implement and the shuttle fleet could resume operations within six to nine months, CAIB chairman Harold Gehman said Tuesday.

On the issue of crew escape and crew survivability, however, Gehman said the board is going to leave that topic up to NASA to deal with.

NASA officials, meanwhile, already are considering several survivability enhancing options to implement in the post-Columbia era. Among them:

• Fly all missions into the same orbit as the ISS so that a shuttle can dock with the outpost and a crew can stay there until a rescue mission is dispatched. An already planned mission to service the Hubble Space Telescope is the only exception currently on the books.
• Equip and train crews to inspect and repair heat protection tiles while in orbit. A team at Mission Control is already working on hardware, procedures and crew training.
• Launching a shuttle mission only when another shuttle is either ready or nearly ready to fly. This idea "feels good" but many shuttle officials, including O'Connor, think it unworkable given there are only three shuttles in the fleet.
• Reducing crew size. Although this doesn't increase the odds of survival, it does reduce the number of people exposed to the risk. But until the OSP is ready, this also could be considered unworkable.

In any case, there's nothing that can be done immediately to protect a crew during all phases of launch, mission and landing.

None of the concepts being discussed or worked on would have prevented the loss of Columbia's crew during re-entry, officials said.

As always, much will depend on the willingness of Congress to pay for the necessary improvements to the shuttle fleet while also being asked to fund development and construction of the new OSP.

"It's been a difficult challenge to figure out how to improve crew escape over what we have now," O'Connor said.

Much also will depend on the American public continuing to accept the inherent risk that is part of spaceflight -- as the Challenger and Columbia disasters have reminded everyone.

"The risk can be zero if we quit flying," O'Connor said.

"When you ask people what the shuttle program's priorities are, they don't say 'Safety is number one.' A lot of people think that we say that but we don't. What we say is 'Flying safely is our first priority.' So flying is an equal partner with risk."