shuttle_20th_mainbar CAPE CANAVERAL, Fla. NASAs space shuttle fleet will mark 20 years in service Thursday, and with no heir apparent, experts are calling for flight safety improvements to avoid catastrophe during the coming generation of U.S. space exploration.
Two decades after Columbia lifted off on the agencys first shuttle flight, the $8 billion fleet is playing a pivotal role in the most ambitious construction project ever attempted in orbit, hauling crews and cargo to and from the growing International Space Station (ISS).
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At the same time, a billion-dollar bid to build a half-scale prototype of a would-be successor ship was written off last month, making it increasingly likely that the shuttle will be flying well beyond its advertised retirement date in 2012.
Senior NASA shuttle program managers are preparing for the long haul ahead.
But an independent safety organization already is raising red flags, calling on the agency, Congress and the Bush administration to face the inevitable: A shuttle service life of another 20 years or more.
Consequently, the Aerospace Safety Advisory Panel is urging the nation to plan now for shuttle fleet upgrades that will reduce inherent risk for future astronaut crews.
"It is inescapable that for the foreseeable future the space shuttle will be the only human-rated vehicle available to the U.S. space program for support of the ISS and other missions requiring humans," the panel of experts said in an annual report released earlier this year.
Chartered by Congress after
the 1967 Apollo 1 launch pad fire that killed three astronauts, the independent group lauded NASA for shuttle safety upgrades to date.But further improvements can "enhance the safety and operability of the space shuttle, particularly if it is to fly another 20 years or more," the panel said, adding, "the failure to adopt as many of these as possible in a timely manner would be ill-advised."
The reason: No shuttle replacement is likely to fly during the life of the international station, which is expected to operate for a decade after outpost construction is completed in 2006.
The bottom line: "Delaying the implementation of some of the identified improvements while awaiting a decision on the service life of the space shuttle exposes flight crews to higher levels of risk for longer than necessary," the panel said.
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Five years ago, the outlook for the shuttle fleet was decidedly different.
At that time, NASA and U.S. aerospace giant
Lockheed Martin set out to build a prototype of a revolutionary, fully reusable spaceship that would leap into orbit in a single bound, without shedding throwaway fuel tanks or rocket stages along the way.The idea was to cut the high cost of shuttle launches typically, about $400 million by a factor of 10, providing inexpensive access to the high frontier.
The
so-called X-33 project, however, hit a major snag in 1999 when a lightweight fuel tank made of composite materials rather than heavier aluminum cracked during a development test.Put on hold as a result: 15 test flights that were expected to lead to the development of a full-scale Lockheed Martin shuttle replacement vehicle dubbed
VentureStar.NASA finally pulled the plug on the project last month after an investment of $912 million. Lockheed Martin spent $356 million of its own money on the X-33 but said the company could not continue the project without additional government funding.
The company had hoped NASA would funnel extra money to the X-33 project from the agencys so-called Space Launch Initiative (SLI), a five-year, $4.5 billion program begun last year in hopes of developing a next-generation spaceship to replace the shuttle.
The death knell sounded when the X-33 failed to qualify for any of that money.
"This has been a very tough decision, but we are confident it is the right business decision," said Art Stephenson, director of NASAs Marshall Space Flight Center in Huntsville, Alabama, which manages the agencys advanced space transportation efforts.
"Our technology has not yet developed to the point that we can successfully develop a new reusable launch vehicle that substantially improves safety, reliability and affordability."
NASA now is negotiating contracts with several companies as part of the SLI effort. The agency plans to spend $765 million on the project in the next two years.
Still unclear, however, is whether a replacement vehicle will be available by the shuttles stated 2012 retirement date. "Its uncertain right now," Elric McHenry, manager of shuttle development for NASA, told SPACE.com.
This much, however, is sure: NASA is depending heavily on the shuttle to build the international station, a $60 billion project being carried out in concert with space agencies from Russia, Europe, Canada, Japan and Brazil.
A reliable frequent flier also will be needed to haul rotating crews and fresh supplies to and from the station during a subsequent decade or more of scientific research in low Earth orbit.
"Theres been a tremendous shift in focus because all of a sudden, the shuttle is the only game in town," said former NASA astronaut Andrew Allen, now a senior manager with shuttle prime contractor United Space Alliance.
"We have an International Space Station that cant be built without the space shuttle, and realistically, it probably cant be maintained without the space shuttle," Allen said. "And thats become very apparent to everybody."
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With the 2012 retirement date still officially in place, NASA already plans to invest an estimated $1.6 billion over the next five years to replace outdated shuttle components.
Chief among the improvements:
- New electric auxiliary power units. Cost: $224 million.
Shuttles now employ three auxiliary power units (APUs) to provide the hydraulic power needed to steer its main engines and control the ships wing flaps, rudder speed-brake, landing gear and nosewheel steering system.
The units, however, are powered by hydrazine a very toxic, corrosive and combustible fuel that makes the devices vulnerable to leaks, fires and even explosions.
New electric units like those flown on the militarys F-22 jet fighters and Comanche helicopters would be less susceptible to potentially deadly failures.
They also would eliminate toxic hazards now encountered when the units are serviced on the ground, and that, in turn, would speed up turn-around time between flights.
- An advanced sensor system for the shuttles main engines. Cost: An estimated $108 million.
Together with twin solid-fuel rocket boosters, the shuttles three liquid-fueled main engines provide the propulsive power needed to launch into space. An inadvertent engine shutdown, however, could trigger a catastrophic explosion in flight.
Advanced engine sensors, along with state-of-the-art monitoring computers, would be able to detect failures instantly and automatically cut off engines before shutdowns could occur.
"That will give us the capability to determine -- within a fraction of a second -- whether we have an incipient engine failure occurring and be able to shut the engines down," McHenry said.
Some 30 to 40 percent of catastrophic engine failure scenarios could be avoided as a result.
- Redesigned engine combustion chambers and nozzles. Cost: $400 million.
Shuttle main engines now sport combustion chambers and nozzles that feature individual welds that can fail, triggering potentially deadly fuel leaks in flight.
New designs and manufacturing processes would significantly reduce the number of welds and potential failure points -- within shuttle engines.
- An advanced "smart cockpit." Estimated cost: $400 million.
Shuttles Columbia and Atlantis now are equipped with
new "glass cockpits," which feature full-color flat panel displays that replace old cathode ray tubes and electromechanical gauges. Sister ships Discovery and Endeavour will be outfitted with the new dashboards in the next two years.NASA, however, intends to take cockpit technology to the next stage by developing computers and new software that will automatically detect in-flight failures and instantly display corrective action for a shuttle commander to take.
Once the so-called "smart cockpits" are in place, astronauts no longer will have to go through the time-critical process of identifying a system failure and then figuring out what action to take in an emergency. The new computers will provide the artificial intelligence needed to do that job.
"What we expect to do with the smart cockpit is provide them with much better information that makes their decision-making much quicker and simpler," McHenry said.
"Rather than having them play detective and look at various hardware failure cues, this will provide them with resolution: What the problem is, what the root cause is and what the recommended action would be," he added.
"So its going to be a lot simpler, we believe, for them to manage a critical flight scenario."
Other improvements also are in the works.
NASA intends to beef up the shuttles landing gear and its tires to reduce the chance of blowouts and other failures during end-of-mission or emergency landings.
In addition, new manufacturing techniques are being developed to speed preflight rocket booster and external tank inspections.
Lumped together, the planned shuttle upgrades are expected to reduce the odds of a catastrophic failure in flight from one in 438 today to one in 735 by the year 2005.
The independent safety panel, however, is urging NASA to go well beyond that.
NASAs planning for shuttle safety upgrades, the group noted, has a relatively short five-year horizon, a time frame largely dictated by the 2012 retirement date.
But given the fact that the shuttle likely will be flying to 2016 or beyond, the panel is calling for a "firm national commitment" to the fleet for the entire life of the international station.
A more realistic retirement date, the group said, would free NASA to focus on long-term safety improvements, such as an advanced shuttle crew escape system.
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The current system -- a telescoping pole that would allow astronauts to bail out a side hatch -- is largely regarded as inadequate for most launch failure scenarios.
The reason: A shuttle would have to be in a controlled glide above 20,000 feet (6,067 meters) for the system -- which was incorporated after
the 1986 Challenger disaster -- to be of any use. Said the safety panel: "The time is past due for the implementation of a more capable crew escape system."
NASA also is eyeing a more robust shuttle rocket booster system, one with enough propulsive power to avoid a risky and unprecedented emergency landing after an engine failure in flight.
Either of those major upgrades would cost a billion dollars to put in place. But program managers say such an investment might be prudent if the fleet is going to fly 20 or 30 more years.
"Anything we can do to take risk out of flying the vehicle, we think, is a worthwhile thing to do," McHenry said.
At the same time, project officials are quick to note that shuttle airframes each are certified for 100 missions
and that the fleet leader -- Discovery -- only has 29 flights to its credit.And given a current flight rate of seven or eight missions a year, timely upgrades and proper maintenance is all that is needed to keep the fleet flying safely into the distant future.
"I know that if we keep the shuttle flying safely, if we use the right tender-loving-care approach, if we upgrade and keep it supportable in the right ways, then we can fly this vehicle for the next 20 years," shuttle program manager Ron Dittemore told SPACE.com.
"Whether or not we will need to do that is another question," he added. "But I know that we can keep it flying safely for the next 20 years."
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