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Downlinks with Miles O'Brien

At last, space shuttle may live up to promises

Shuttle commander Jim Halsell, left, and O'Brien inside the cockpit of Atlantis at NASA's Kennedy Space Center

IPIX 360° images of Atlantis



May 4, 1999
Web posted at: 1:17 p.m. EDT (1717 GMT)

KENNEDY SPACE CENTER, Florida (CNN) -- I've been thinking about age a lot lately. My 40th birthday is on the near-term horizon, and milestones like that tend to put one in a chronological -- albeit sometimes illogical -- frame of mind (suddenly a tricked-out Corvette seems like a most excellent idea).

Anyway, I do know this: actuarially speaking, I am a little more than half-cooked, and yet mentally and physically, I feel like a spring chicken.

So it is with NASA's fleet of space shuttles. How many times have you seen a particular shuttle described as "aging?" It has almost become conventional wisdom. After all, the shuttle was largely designed in the first era of bell-bottoms and platform shoes. And while those fashions are (for reasons I cannot comprehend) once again on the cutting edge, the 20- to 30-year-old system designs on the shuttle are not.

So what is NASA doing about it? On the one hand, they are looking at the next generation of reusable spacecraft. The X-33 experimental, unmanned spaceship, being built by Lockheed Martin, is designed to reach low Earth orbit on a single stage -- that is, without shedding booster rockets or fuel tanks.

No one will quibble with the concept: a single stage ride into the void would clearly be much cheaper and easier to operate. But there are many technological hurdles and uncertainties ahead.

Which is why NASA -- and its prime shuttle contractor the United Space Alliance (USA) -- are taking a new look at the old family station wagon. And they are thinking "maybe she's got a few good miles left in her after all."

For starters, the orbiters were designed to safely fly 100 missions each. The current fleet of four shuttles has a combined 83 missions on their odometers -- Columbia and Discovery have each flown 25 flights, Atlantis has logged 20 and Endeavour 13. That means they have a theoretical lifespan of 317 missions. At the rate they have flown to date -- 93 missions (Challenger flew 10 times) over 18 years = 5.166 flights per year -- shuttles could theoretically fly for another 61.36 years, or until 2060.

Sound far-fetched? Probably. But consider this: the Air Force is still flying B-52s some 40 years after they first joined the inventory. And there is talk they may fly until 2040. Don't judge a plane by its skin. The old bombers have been modified, overhauled and retrofitted extensively.

And so it may be with the shuttle. When I crossed the threshold of Atlantis this past week, I am told by NASA and USA that I had entered the "most modified shuttle ever." The most obvious change is on the flight deck. Where there were once 32 meters and gauges, there are now 11 flat panel displays with rich colors and more easily understandable presentations. It's not unlike the cockpits of airliners built in the last decade or so.

Jim Halsell, commander of the first Atlantis mission to fly with the glass cockpit (STS-101, now slated for December 1999) was there dressed in the same dust-limiting bunny suit I had donned. He says the instruments -- known as the Multifunction Electronic Display System (MEDS) -- make it easier for the crew to react quickly to a problem. Maybe it's only a fraction of a second, but in this racket that can mean the difference between "off-nominal" (a glitch) and "criticality-one" (catastrophic loss of orbiter and crew).

There are other modifications that are less obvious -- from better brakes to a lighter external fuel tank -- that separate Shuttle 1.0 from the latest iteration. As a result, criticality one failure probabilities in the main engines have been reduced 83 percent to 1 in 993. The solid rocket boosters (culprit in the Challenger disaster) now pose a 1 in 1,152 chance of causing a catastrophic failure -- a 76 percent improvement in the past seven years. Overall, the chances of a shuttle having a criticality one failure are now 1 in 438. That means statistically, the shuttles could fly out their useful life without a calamity.

The bottom line is NASA and the United Space Alliance are pushing hard to keep flying the shuttle -- and perhaps harder than ever. There is talk about how reliable the shuttle has become (now 98.8 percent) ... how much cheaper it is to fly (a 36 percent reduction in the past six years). And there is talk of an astounding 15 missions per year.

Maybe the shuttle finally can deliver on its promise to provide routine access to space. But the still-uncompleted International Space Station is supposed to become NASA's primary scientific platform, and unmanned rockets are doing the heavy lifting in the commercial category. So could the shuttle fleet be all dressed up with no place to go?

Space Correspondent Miles O'Brien's column appears on Tuesdays.

Downlinks with Miles O'Brien

Downlinks archive

With fanfare, NASA rolls out space plane prototype
April 30, 1999
Shuttle Atlantis in the shop for a tune-up
March 9, 1998
Shuttle Atlantis back on Earth
October 6, 1997

VentureStar -- X-33 -- Single Stage to Orbit -- Reusable Space Plane -- RLV SSTO
NASA Human Spaceflight: the shuttle
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