Japan's new space freighter won't make the jump to light speed like the Millennium Falcon, but it could pave the way for future human spaceflight endeavors.
The H-2 Transfer Vehicle (HTV), as it?s called, is scheduled to make its launch debut Thursday atop an equally brand new H-2B rocket. The Japan Aerospace Exploration Agency (JAXA) hopes that a successful debut for both vehicles will establish the technologies for more ambitious missions beyond Earth orbit.
"From the JAXA perspective this is a test flight," said Masazumi Miyake, the deputy manager of JAXA's Houston office. "But we will bring several payloads to support ISS [International Space Station] logistics and crew."
A successful launch from Japan's Tanegashima Space Center Thursday at 1:01 p.m. EDT (1701 GMT) would allow HTV-1 to deliver 3.5 tons of needed supplies to the space station. The cylindrical Japanese space freighter would then join Europe's Automated Transfer Vehicles and the Russian Progress spacecraft in resupplying ISS after the space shuttle fleet retires in 2010.
But first, everything from launch to docking must go smoothly with what is still an untested spacecraft on an untried rocket. Astronauts will also have to perform the first-ever free-flyer capture of a spacecraft from the space station to pluck the HTV from space.
Up and away
Japan's new H-2B rocket is a step up in size from the country?s earlier H-2A rocket, but can carry more than double the payload to orbit. That means JAXA can move from launching satellites to full-fledged unmanned or possibly manned spacecraft.
Miyake said that H-2B shares many of the same reliable components with H-2A, and so JAXA has confidence in this rocket's maiden flight.
"The launch vehicle is on its first flight, but most components and subsystems are the same as H-2A launch vehicle," Miyake told SPACE.com. "The difference is that we have four [solid rocket] boosters rather than the two on H-2A, and two main engine thrusters rather than the one on H-2A."
H-2A has just one failure compared to 14 successful launches on record, and has previously lofted hardware such as Japan's moon orbiter Kaguya. The larger H-2B rocket also requires about 1.7 times more propellant than its smaller predecessor. It stands about 187 feet (57 meters).
The extra carrying capacity allows H-2B to lift almost eight tons to a geostationary transfer orbit. The ?16 1/2-ton HTV-1, meanwhile, is destined for a lower orbit to reach the space station, which flies 220 miles (354 km) above Earth.
Just as Japan's new rocket relies upon prior systems, the $220-million HTV-1 also draws upon existing technology from Japan's massive Kibo laboratory on the space station.
Kibo is a giant facility the size of a tour bus that houses experiments in a pressurized interior pod, an attic-like storage room and an external science platform. It has its own robotic arm, two windows and a small airlock.
The HTV-1 is 33 feet (10 meters) long, 14 feet (4.4 meters) wide and covered in solar panels to power its onboard systems. It can haul up to six tons of cargo for use both inside the space station and outside, and will be toting both types of supplies when it lifts off on Thursday.
"It?s the first unmanned vehicle that brings with it both pressurized and unpressurized cargo," NASA space station flight director Dana Weigel said in a recent briefing. "It's also the first unmanned vehicle going to the U.S. segment, and the first free-flyer capture from ISS."
A free-flyer capture means that space station astronauts must use a Canadian robotic arm to grab the free-floating HTV-1.
The space freighter does not automatically dock like the European and Russian spacecraft. Instead, a preprogrammed computer controls HTV-1's approach up until the moment of robotic grapple. The robotic arm operator, NASA astronaut Nicole Stott, must then seal the deal within a 99-second capture clock.
"The rendezvous is mostly automatic as HTV is approaching ISS," Miyake said. "At the last minute, the onboard crew has the capability to abort HTV if something happens to the automatic system."
Miyake added that Japanese engineers previously tested such docking technology with satellites.
Moving to manned spaceflight
No concrete plans exist yet for a Japanese manned space program, even if Japanese astronauts have already flown to the space station and tested odor-free underwear in microgravity. But HTV-1 could provide some of the core technologies for Japanese astronauts to take their own rides into space.
"Currently HTV will be disposed of in the atmosphere," Miyake said. "But if we could add some return capability to HTV, it could be one of the technologies for manned spaceflight."
Such a development could parallel European proposals to refit their ATV cargo ship for proper reentry, rather than simply burning up in the atmosphere. Miyake noted that upgrading the HTV design represents a real possibility for the future.
"We hope that this HTV technology will contribute to future moon and Mars missions, and to international cooperation," Miyake said.
The Japanese space freighter may soon fulfill the international collaboration part of those wishes, as long as the mission goes as planned. Robert Lightfoot, deputy director of NASA's Marshall Space Flight Center, enthusiastically described HTV's role in that sense during a public meeting in July of a White House-appointed panel reviewing NASA?s human spaceflight plans.
"I sat in the HTV review last week for the Japanese transfer vehicle and that is one of the neatest reviews I have ever been in because you had the Canadian Space Agency, you had JAXA, and you had the U.S. side talking about how we are going to actually capture this free-flyer HTV and we are going to use the Canadian arm and go grab it," Lightfoot said.
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SPACE.com will provide complete coverage of Japan?s HTV test as well as NASA?s ongoing Discovery shuttle mission to the International Space Station. Click here for SPACE.com?s space station coverage and a link to NASA TV, which will broadcast the launch Thursday beginning at 12:45 p.m. EDT.