As NASA
marks 25 years
of shuttle flight this week, the space agency is looking ahead to its next
spaceship to reach for the orbit and the Moon.
The space
shuttle Columbia ushered in NASA's shuttle era on April 12, 1981, when it launched
spaceward with STS-1 astronauts John Young
and Robert
Crippen aboard.
A quarter
century later, NASA's aging shuttle fleet is destined for retirement
in 2010 as the space agency returns to a capsule-based
spaceflight with its $104-billion Crew Exploration
Vehicle (CEV) plan. The agency's new spaceship to is expected to debut no
later than 2014 to serve the International Space Station (ISS) , and push
towards the Moon and possibly on the Mars.
"The
shuttle was a 'do everything for everybody' vehicle," Scott Horowitz, NASA's
associate administrator for the agency's Exploration Systems Mission
Directorate, told SPACE.com. "We
built a reusable spacecraft, which had never been done before. But it was more
difficult to do than many people imagined."
Horowitz
said NASA is taking lessons from the shuttle's two tragic failures - the loss
of 14 astronauts during Columbia's
2003 failed reentry and the Challenger
launch accident of 1986 - and the agency's spectacular successes, such as
the Apollo Moon effort,
to push ahead with its new human-carrying spacecraft.
"The
shuttle showed us how to operate routinely in space and reaffirmed that going
into [orbit] is difficult," he added.
Crew
safety and escape
NASA's
biggest lesson from its 114 shuttle flights - which it learned the hard way
through accidents and sacrifice - has been the need for a quick and dependable way out for
astronauts in case of a launch or landing emergency.
"We learned
we need to have a dedicated vehicle to launch crew with a robust escape
system," Horowitz said.
During
Columbia's STS-1 mission and three subsequent test flights, all of which were
flown by two-astronaut crews, the orbiter carried ejection seats for commander
and pilot should they need to bail out of the vehicle - after first blowing the
roof off the cockpit - at key moments. A bail
out escape system was installed on shuttle middecks
following the Challenger accident.
"Truthfully,
I'm not sure that they could have handled many contingencies," Crippen told SPACE.com
of the ejection seats, adding that it's unlikely they could have handled
extreme failures like the Columbia or Challenger incidents. "With this
[new] vehicle, we'll be able to put in an escape system that we weren't able to
do with shuttle."
The CEV is
expected to boast escape rockets capable of wrenching the crew capsule away
from its booster during launch. Its broad, stubby heat shield concept is
reminiscent of NASA's Mercury,
Gemini
and Apollo
programs, and still employed by Russian
and Chinese
reentry vehicles today.
"We do know
that those launch escape systems work," said Roger Launius,
a former NASA historian and chair of the Division of
Space History at the Smithsonian Institution's National Air and Space Museum in
Washington, D.C. "We tested them unmanned on Mercury and Apollo, and the
Russians have aborted twice in launches and succeeded in bringing the crew
back."
Higher perch
For some
astronaut veterans, an attractive feature of a capsule-based CEV is the added
distance between its crew cabin and the main engine down at the bottom of its
booster. During shuttle launches, astronauts sit in a crew compartment
separated from the three main engines in the aft by a 60-foot (18-meter)
payload bay.
"We always
worried most about those and blowing the back end off
the ship," former astronaut Tom Jones, a four-flight shuttle veteran, told SPACE.com. "If you had an engine explode
on the way to orbit, it would probably have damaged the orbiter to the point
that it couldn't return safely, and then the crew is lost."
With the
capsule on top, the astronauts need not worry about foam
insulation or other debris striking their spacecraft during launch, Jones
said.
"We can at
least look at the way the shuttle was fatally flawed, and make the CEV
bulletproof to those threats," he added.
More
focused spaceflight
The shift
back to an Apollo-like capsule spacecraft will borrow from NASA's shuttle
experience, NASA officials said. The agency plans to draw on its shuttle solid
rocket boosters and external tanks to construct separate CEV
crew and cargo launchers, they added.
But in
return for the new system, NASA is trading the substantial performance
capabilities of its shuttles, which have allowed astronauts to assemble the
ISS, as well as repair satellites and the Hubble
Space Telescope in orbit. The shuttle is also able to return tons of
hardware to Earth from the ISS, with much of its flexibility stemming from its
catch-all design.
"It's a
remarkable vehicle [and] it does things that no other vehicle has ever done,
and may not do for awhile," NASA shuttle program manager Wayne Hale said in an
interview. "It has its limitations and we, as a spacefaring
people, should have been building the next
generation shuttle long ago...I think it will be well past time for the
shuttle to retire when we roll it into the Smithsonian."
Launius,
however, said he is concerned that NASA may spend years developing the CEV,
only to be stymied after the shuttle is retired and be effectively left without
a dedicated human spaceflight capability.
"The landscape
right now is littered with would-be shuttle replacement programs," Launius said, referring to past NASA projects like the National
Aerospace Plane, the Orbital
Space Plane, the X-34 and others.
"Each of those projects ran aground for a variety of reasons, usually
technological or financial...and in each of those terms they hit the reset
button."
The
challenges, Launius said, are very real for NASA's
CEV, which the space agency hopes to launch no later than 2014.
"I hope
they're able to move forward with CEV and bring it online," he said.
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