Instead of
flying high above Earth this week, NASA's shuttle Discovery is crawling down
from its launch pad to switch external tanks, a move that has delayed its
flight and caused dismay among astronauts on Earth and in space.
"I know
that people are disappointed when the shuttle launch delays...it is a
disappointment," said veteran astronaut Eileen Collins, commander of Discovery's
STS-114 mission, during a press conference this month. "But we want to make
sure we understand everything that we're studying and that we don't rush into
things."
Before the current
delays, Discovery's seven-astronaut crew planned to launch spaceward on Sunday,
May 22 for a 12-day flight that would not only return NASA's independent
ability to loft humans into orbit, but also shakedown new safety measures and
resupply the International Space Station (ISS).
However, concerns
over the potential danger of ice
debris from Discovery's external tank led mission managers to call for a swap,
drawing out the shuttle's launch to no earlier
than July 13.
Discovery's
launch delay not only tacked extra time on Earth for the seven STS-114
crewmembers, it also lengthened the amount of time the space station -
currently manned by the two-member crew of Expedition
11 - must wait for a shuttle resupply mission. NASA space shuttles have not
visited the ISS since December 2002, when the Endeavour orbiter undocked
from the station and returned to Earth during the STS-113
mission.
"We'd
rather see the space shuttles up here sooner rather than later," said NASA
astronaut John Phillips, flight engineer for Expedition 11, during a NASA TV video
downlink with CBS News. "I was certainly disappointed."
But the
astronauts agreed that, launch chagrin aside, paying strict attention to safety
and risk management - not schedules - should be the prime concern for NASA's
space shuttle program.
"It was the
failure of risk management that led to the Columbia disaster," STS-114 mission
specialist Andrew Thomas told Australian reporters via NASA TV. "So I think
these steps of risk management that you're seeing are entirely appropriate."
NASA's three
remaining space shuttles have been grounded since Feb. 1, 2003, when the
Columbia orbiter broke apart during reentry, killing all seven astronauts onboard.
Wing damage sustained at launch by external tank foam debris was later found to
be the accident's cause. Engineers have since redesigned
the fuel tank to for all future shuttle flights.
Once Discovery rolls back inside the 52-story Vehicle Assembly Building, engineers will pry the orbiter from its launch stack and attach it to another one whose external tank bears a new heater to eliminate harmful ice debris from shaking loose of its external tank. The rollback process was itself delayed slightly to allow shuttle engineers time to check Discovery's landing gear for cracks.
Mixed
emotions
For the
STS-114 crew, there are two sides to Discovery's launch delay.
"I think it's
a mix of frustration and relief," Thomas said. "It's also given us a bit of
leeway, so we have some time to relax and collect our thoughts."
The last
few weeks of April were packed full of training maneuvers, from sunrise to
sunset, as the crew ramped up to Discovery's May launch date, STS-114
astronauts said. That April training led to an early May dress rehearsal
of the final hours before launch, during which Discovery's crew donned orange
flight suits and climbed inside their orbiter for the mock-launch abort.
"Every
flight has a certain amount of anxiety to it," Thomas said, adding that STS-114
is no different. "This is probably one of the most important shuttle flights in
20 years...we're going to show that the agency has bounced back and recovered
from that terrible accident."
In fact,
Discovery's launch date has slipped much further than the nearly two months
between May 22 and July 13. The STS-114 astronauts were initially slated to
launch in March 2003 following Columbia's ill-fated STS-107 flight. After the
initial shuttle grounding, several launch dates were announced, then
missed
as engineers and mission managers revamped Discovery and its Atlantis sister
ship for safer flight, modified the external tanks and developed new tools
and methods for in-orbit repair demonstrations.
"Put
altogether, it's going to be a very ambitious mission," Thomas said. "I look
forward to getting on with it."
The view
from space
Meanwhile,
the two Expedition 11 astronauts aboard the ISS are eagerly awaiting Discovery's
launch, if not just for the company of another seven humans at the station.
Phillips
and Expedition 11 commander Sergei Krikalev have worked feverishly to prepare
for Discovery since entering
the space station on April 17.
On May 25,
they rehearsed the photography inspection procedures they will perform as
Discovery flips around during docking to expose its thermal tile-covered
underbelly to the ISS crew. Krikalev and Phillips have also practiced airlock
operations to prepare for the three spacewalks planned while Discovery is
docked at the space station, as well as packed up trash, used equipment and
other unneeded items that will eventually return to Earth with the shuttle.
Krikalev
pointed out that while Discovery's slow progress toward launch may be
disheartening to NASA personnel at Houston's Johnson Space Center, and Florida's
Kennedy Space Center, there are global effects as well.
"Not only
are people in Houston and Florida disappointed, but also NASA's international
partners," said Krikalev, a veteran Russian cosmonaut, during the video
downlink. "The problem is integrated, and every delay has a chain effect."
Without
regular shuttle flights, space station crews have depended on Russia's Soyuz
and Progress
spacecraft to deliver new astronauts and cargo to the ISS. Discovery's delay
could also stretch the timeline needed to complete construction
of the ISS, NASA officials have said.
"We have
three big electrical trusses, a Japanese lab, a European lab and other
components all waiting to launch," Phillips told SPACE.com of the station's
shuttle needs before his mission. "In order to complete the station, we have to
get the shuttle flying."
advertisement
