Japan's
first unmanned cargo ship is closing in on the International Space Station, where
six astronauts are eagerly awaiting its arrival.
The cargo
ship, called the H-2 Transfer Vehicle 1 (HTV-1), is due to arrive at the space
station today at 3:50 p.m. EDT (1950 GMT) after a week-long shakedown cruise. The
Japan Aerospace Exploration Agency (JAXA) launched the spacecraft last week on
a maiden
voyage to deliver tons of supplies for the station's six-person crew.
"It's very
exciting," JAXA spokesperson Naoko Matsuo told SPACE.com. "[Today's] maneuver
is a very critical mission, so we hope we can show our techniques well."
The HTV-1
is Japan's first automated spacecraft capable of ferrying
vital supplies for use inside and outside the International Space Station.
It is the latest spacecraft to join an international fleet of unmanned cargo vehicles
serving the station, which include Russia's Progress freighters and the
Automated Transfer Vehicles built by the European Space Agency.
But unlike
the other disposable cargo ships, the HTV-1 is not designed to dock at the
space station on its own. Instead, it will fly up below the station to a point
about 33 feet (10 meters) from the orbiting lab.
From that
point, station astronauts Nicole Stott of NASA and Frank de Winne of Europe
will have just 99 seconds to grab onto the Japanese spacecraft using the space
station's Canadian-built robotic arm. It will be the first time the station arm
will be used to grapple a free-flying spacecraft.
"I have
every confidence that the vehicle is going to be stable and operate as we
expect," Stott said in an interview before flight. "And I also have confidence
that if that doesn't happen, we have been trained to handle it."
Stott and
de Winne have a remote control panel inside the station that they can use to command
the HTV-1 to retreat away from the station if today's rendezvous goes awry. But
so far, the spacecraft has performed well during a series of free-flying abort
and rendezvous tests.
"We have no
problems," Matsuo said. "So everything is going well."
JAXA
launched HTV-1 early on Sept. 11 Japan Standard Time using the brand new
H-2B rocket, which lifted off from the Tanegashima Space Center in southern
Japan. It was still afternoon on Sept. 10 at NASA's station Mission Control Center in Houston at launch time.
JAXA also
built the space station's $1 billion Kibo laboratory, a massive
facility the size of a tour bus that has two windows, an attached storage
room, robotic arm, small airlock and exterior science platform. The Kibo lab
was completed in July after more than a year of space construction.
Station's
new delivery ship
The HTV
spacecraft is 33 feet (10 meters) long, 14 feet (4.4 meters) wide and covered
in solar panels attached to its cylindrical hull. It is capable of hauling up
to six tons of cargo to the space station, but HTV-1 is carrying about five
tons for its maiden flight, NASA officials said.
Unlike the
station's European and Russian cargo ships, the vehicle is designed to carry
pressurized cargo for use inside the station, as well as unpressurized
cargo for use outside the outpost. The external hardware rides on a giant
drawer that can be plucked from the cargo ship with the station's robotic arm. HTV-1
is carrying two experiments to study Earth's atmosphere and the space
environment.
Reliable
cargo shipments from different spacecraft are vital to continue supporting the
space station's six-person crew. NASA's space shuttle fleet is due to retire by
2010 or so, and with it will go the shuttle's ability to haul massive loads to
the orbiting laboratory.
JAXA
officials have said that about $680 million has been spent developing the HTV
spacecraft since 1997. The HTV-1 vehicle alone costs about $220 million and is
designed to be jettisoned to burn up in Earth's atmosphere after about a month
at the station, they added. Japan plans to build one HTV a year to support the
space station crew.
The station
is currently home to two Americans (Stott is one of them), two Russians, a
Canadian and de Winne, a Belgian astronaut representing the European Space
Agency. The astronauts have been anticipating HTV-1's arrival with a series of practice
sessions to rehearse today's planned rendezvous and grapple.
"We see ourselves
complete with for preparations for HTV-1," Stott radioed Mission Control
Wednesday.
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