The Japanese space agency launched a powerful new rocket Thursday carrying an unmanned space station cargo ship on a complex maiden voyage to deliver some 7,400 pounds of equipment and supplies to the orbital outpost.
With four strap-on boosters gushing white-hot exhaust and a pair of hydrogen-fueled main engines roaring at full throttle, the H-2B rocket thundered away from launch pad 2 at the Tanegashima Space Center in southern Japan at 1:01:46 p.m. EDT.
"The launch was beautiful," Stephen Clark, a U.S. journalist representing Spaceflight Now, said in an instant message from Tanegashima. "The boosters lit with the typical orange glow and away she went. The rocket went into a thick cloud layer around 25 seconds after liftoff, but the rumble shook us for a couple minutes more."
The H-2B's first and second stages worked as planned and 15 minutes after liftoff, the HTV cargo craft was released into its planned preliminary orbit, prompting an enthusiastic round of applause in the Japanese control center.
The $680 million mission represents a critical milestone for the post-shuttle space station program as NASA and its international partners work to keep the lab complex resupplied after the space shuttle is retired late next year.
The HTV cargo craft, developed by the Japan Aerospace Exploration Agency, or JAXA, as a contribution to the station program, measures some 32 feet long, 14.4 feet wide and weighs some 23,000 pounds when carrying a full 13,200-pound load of cargo. For its maiden flight, the HTV-1 is carrying about 3.5 metric tons of equipment and supplies.
Unlike Russian Progress supply ships of the European Space Agency's automated transfer vehicle, or ATV, the Japanese HTV features a pressurized section accessible by the station crew and an unpressurized cargo bay to carry experiments and hardware that can be mounted on the station's hull.
And unlike the Progress and the ATV, the Japanese ship is not designed to dock with the station on its own. Instead, the spacecraft autonomously maneuvers to a position just below the station and waits for the lab's robot arm to grapple it and move it to a docking port.
"On this particular flight, we've got about 2 1/2 tons of pressurized cargo flying to orbit and almost a metric ton of payloads externally coming to ISS," space station Program Manager Mike Suffredini said at a pre-launch briefing. "So it's a significant amount of up mass to us and it's not only important logistics for the crew, which is a major part of the pressurized capability, but also quite a bit of payloads."
One of the payloads in the HTV's unpressurized cargo bay is a NASA experiment to map the constituents of the upper atmosphere and the other is a JAXA payload designed to study the effects of trace gases on the ozone layer. Both will be extracted from the HTV cargo bay by the station's robot arm and installed on an external porch by a Japanese robot arm on the Kibo lab module.
"Those are very critical things for us to understand relative to understanding our environment and how we affect it and it's good to be able to finally start having this kind of research on board ISS," Suffredini said.
Not only is the flight a maiden voyage for the HTV, it also was the maiden flight of Japan's new H-2B rocket, a much more powerful version of JAXA's hydrogen-fueled H-2A booster. The new rocket features four strap-on solid-fuel boosters instead of two, and two hydrogen-fueled first-stage engines instead of one. The upper stage features a single hydrogen-powered engine.
JAXA currently plans to build and launch one HTV craft per year, although the agency could support two flights annually if necessary.
The HTV-1 flight plan calls for a full week of orbital tests and checkout before final approach to the space station, including tests to exercise the craft's abort modes. Capture is planned for flight day eight.
Final approach will begin at a point about 3.1 miles directly behind the International Space Station. The HTV-1 will maneuver itself to a position about 1,000 feet below the lab complex and then carry out a 180-degree yaw maneuver to permit an abort, if necessary, when the craft is closer to the station.
From there, it will continue the approach to a point about 100 feet below the station and pause once again before proceeding to the capture point just 29 feet from the laboratory complex.
At that point, with the HTV-1 in free drift, station flight engineer Nicole Stott will use the lab's robot arm to lock onto a grapple fixture. Canadian astronaut Robert Thirsk then will take over and guide the HTV-1 to a docking at the Harmony module's nadir, or Earth-facing, port.
The day after capture, the crew will open hatches between Harmony and the HTV and begin moving equipment and supplies into the station.