After
almost five years rooted on Earth, NASA's shuttle Endeavour is again being
primed for launch after a major overhaul to upgrade and refit the 100-ton space
plane.
The shuttle
and its STS-118 astronaut crew are slated to launch Aug. 7 on a construction mission
to the International Space Station (ISS). The upcoming
spaceflight will mark Endeavour's first flight since late 2002 following
several years' worth of maintenance and modifications.
"It's
like a new space shuttle," Wayne Hale, NASA's shuttle program manager,
said of Endeavour, adding that the orbiter has been inspected from stem to
stern. "It's like driving a new car off the showroom floor."
During Endeavour's
down time engineers inspected some 150 miles (241 kilometers) of wiring, enhanced
its avionics interface, and added a new power transfer and engine monitoring systems
among other upgrades.
About the
only current hitch with the orbiter is an apparent
cabin leak somewhere inside Endeavour's crew module, its attached payload
bay-mounted SPACEHAB cargo module or their connecting tunnels and hatches. As
of Tuesday, engineers were still working to isolate the leak's source.
Endeavour,
also known as Orbiter Vehicle-105 (OV-105), is NASA's youngest space shuttle
and was commissioned in 1987 as a replacement for its sister ship Challenger following the loss of
that older orbiter, its six-astronaut crew and Teacher in Space Christa
McAuliffe in January 1986. The shuttle rolled out of its then-Rockwell International
(now Boeing) hangar in Palmdale, California in 1991 to join NASA's orbiter fleet.
Endeavour
is now poised to make its 20th launch into space on NASA's STS-118 mission
to deliver cargo, spare parts and a new piece of starboard-side framework to
the ISS. Commanded by veteran astronaut Scott Kelly, the mission also features the
first flight of teacher-turned-spaceflyer
Barbara Morgan, who served as McAuliffe's backup in 1986.
Endeavour's
new tech
Standing
out among Endeavour's nearly 200 modifications is a trio of systems making
their first operational appearance on a NASA shuttle flight.
The shuttle
is NASA's first to carry a Station-Shuttle Power Transfer System (SSPTS), which
is designed to allow Endeavour to siphon electrical power from the station's
120-volt grid via a docking port connection. The system then converts that
power to feed the orbiter's 28-volt system. If successful, the new power transfer
system will allow the STS-118 astronauts to conserve Endeavour's own fuel cell
supplies.
"[A]ssuming
that it works, we'll be able to fly a 14-day mission so we can add three extra
days to our flight," Kelly said in a NASA interview.
Endeavour also
sports the first fully activated Advanced Health Management System to watch
over the shuttle's three main engines during launch, as well as a three-string
global positioning system (GPS) for pinpoint navigation during landings, NASA
said.
The health
management system is designed to monitor vibrations in each of the high-pressure
fuel and oxidizer turbopumps - which rotate 34,000 times and 23,000 times per
minute, respectively - that feed Endeavour's three main engines with the 526,000
gallons (1,991,126 liters) of propellant required for the 8.5-minute launch
into space. If an engine's turbopumps vibrate too much, the new system is
designed to shut it down.
"An
engine would be shut down before it could progress to any catastrophic
situation," Hale said of the monitoring system.
The three-string
GPS system, which was tested in part on a shuttle flight last year, replaces Endeavour's
1950s-era TACAN system that is gradually being phased out worldwide, he added.
"We've
got a far superior system, far safer, far more accurate to fly our big glider
back home with," Hale said.
Other
major upgrades
In addition
to testing new shuttle technology, Endeavour now also equipped with hardware
already installed aboard its sister ships Discovery and Atlantis.
Perhaps the
biggest bit of shuttle catch up for Endeavour is the addition of its "glass
cockpit," a series of flat screen, full-color multi-functional electronic displays
that present flight data to the orbiter's astronaut crew.
"Endeavour
was the last orbiter to get that modification," Tassos Abadiotakis, NASA's
vehicle flow manager for Endeavour, told SPACE.com. Atlantis first flew with
the upgrade during its STS-101 mission in 2000, followed by Discovery in 2005
during NASA's STS-114 flight.
Like
Discovery and Atlantis, Endeavour is also now equipped to carry a 50-foot
(15-meter) sensor boom, a vital extension of the orbiter's robotic arm that
allows astronauts to scan the orbiter's heat shield in flight to seek out signs
of damage, Abadiotakis said.
The sensor
boom was added as a safety measure following the 2003 loss of seven astronauts
aboard Columbia during landing after the orbiter's heat shield had been damaged
by fuel tank debris.
The
orbiter's wing leading edge sensors, also a post-Columbia safety measure
designed to record any impacts from debris or micrometeorites, sport a new voltage
booster to extend their in-flight operations, NASA said.
A team of
up to 200 shuttle workers helped upgrade Endeavour, as well as perform vital
wiring and structural inspections to once more prepare the spacecraft for
flight.
"I
would say that it's better than when it first rolled out of the barn in
Palmdale," Abadiotakis said of Endeavour. "We basically reset the vehicle,
the clock, back to zero."
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