Japanese Cargo Ship Closes in on Space Station

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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