The end is beginning for NASA's three aging space shuttles,
with just five more missions on tap this year before the orbiter fleet retires
in the fall.
That is, unless NASA needs a few more months to fly those remaining
missions or President Barack Obama chooses to extend the shuttle program to
fill a looming gap in U.S. human spaceflight capability.
Though the ultimate path forward for NASA has not yet been
decided, the space agency is at a turning point after nearly 29 years of
shuttle flight.
"Obviously it's the end of an era," said Roger
Launius, space history curator at the Smithsonian's National Air and Space Museum. "There's a certain amount of nostalgia and a sense of loss, no
question."
The very last space shuttle flight, the STS-133
mission of the shuttle Discovery to the International Space Station, is
scheduled for September 2010. The launch will be the 134th shuttle voyage since
the fleet's debut in 1981.
"It's starting to hit home, I have to admit to you,"
said NASA's shuttle launch director Mike Leinbach after the Nov. 16 liftoff of
Atlantis on the STS-129 flight, the fifth and last shuttle trip of 2009. "After
this one, there's one more scheduled for Atlantis, two more for each of the
other vehicles."
Shuttle legacy
The shuttle has had incredible highs, and terrible lows,
over its decades-long history since the launch of Columbia on STS-1
on April 12, 1981. Fourteen astronauts have been killed and two shuttles,
Challenger and Columbia, lost during accidents.
"It had some very notable and public failures, and
those are often what it's remembered for," Launius told SPACE.com. "The
loss of the two vehicles with the crews was just tragic. But overall, it was a pretty
successful program."
The space shuttle, officially NASA's Space Transportation
System (STS), was the first-ever reusable spacecraft. It consists of a payload
bay-equipped orbiter to carry crew and cargo, with separate reusable solid
rocket boosters to help it lift to space, and a disposable orange external tank
to hold the chilled liquid fuel for its main engines.
"They built a reusable vehicle," Launius said. "That's
pretty remarkable that they pulled that off. Nobody had ever done that before."
But the space shuttle fleet hasn't achieved all its goals.
Originally, NASA conceived it as a system that could fly frequent and
inexpensive trips to space on almost an airline-like brisk schedule.
"It was supposed to be routine, safe and affordable, in
addition to being highly capable. But it was never routine, [and] it was very
expensive," said John Logsdon, a space policy expert and professor
emeritus at George Washington University in St. Louis.
The shuttle's safety record was "decent, but not decent
enough," he said. "It's riskier than we would like for a vehicle
carrying people."
Nonetheless, it accomplished a lot, including the launch and
multiple servicing trips of what's probably the world's best-known and loved
observatory, the Hubble Space Telescope. And the shuttle has played a vital
role in constructing the International
Space Station, the world's largest space laboratory and residence.
"The assembly of the space station could not have been
done without the space shuttle, and the assembly of the space station is one of
the great engineering achievements of mankind," said space shuttle program
manager John Shannon. "So the space shuttle will have done a good
job."
Of course, an unforgettable part of the space shuttle's
legacy will always be its tragic accidents. On Jan. 28, 1986, the world watched
stunned as the shuttle Challenger and its seven-member crew, including teacher
Christa McAuliffe, were lost in a fiery explosion shortly after launch. And
again on Feb. 1, 2003, disaster struck when the shuttle Columbia and its seven
astronauts perished while re-entering the atmosphere during their descent back
to Earth.
"You know, we lost seven astronauts, and that was awful,
just devastating," Leinbach said of the Columbia tragedy. "But we
also lost an orbiter. And it's hard to explain to people, that when we lost Columbia that was like losing a family member almost. It's almost that deep when you work
on these machines day in and day out."
After each catastrophe, NASA took a break to investigate the
failures, and was able to regroup and resume the shuttle program.
The final flights
If the current schedule stays on track, 2010 will see the
launches of the last
five shuttle flights.
Getting so many missions off the ground is a tall order, but
one that NASA has accomplished before — indeed, the agency launched five
flights in 2009. The record for most shuttle launches in a single year (nine
missions in all) was set back in 1985.
"In terms of next year, I think the teams are very well
prepared," said Bill Gerstenmaier, NASA's associate administrator for
space operations, after the final launch in 2009. "We're at the right
pace, the tempo feels good, it doesn't feel rushed. The challenge will be to
just stay focused, just take it one flight at a time."
These last shuttle missions are all slated to travel to the
space station to deliver final rooms and experiments, and to drop off spare
parts to keep it functioning beyond the shuttle's retirement.
After the shuttles are grounded, Russia's Soyuz spacecraft will
be the only vehicle approved to carry humans to the station. NASA has said it
plans to field its replacement craft for the shuttle, the Ares I rocket and the
Orion crew capsule, by 2015.
But outside experts have said it will likely be later,
sometime in 2017, when the new spacecraft will be ready to launch astronauts
into space. An independent committee that reviewed NASA's plan to replace the
shuttle fleet and return astronauts to the moon said last year that
commercially built spacecraft may be able to help ease the coming gap in U.S. manned spaceflight capability.
While the future is uncertain, the year 2010 will be sure to
be an eventful one for NASA, and could mark the end of the space shuttle era.
Shannon said that finale was likely to be bittersweet.
"I'm sure it will be emotional," he said.
"But I suspect that it will not be sadness over the passing of that era,
but happiness that we were a part of it."
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