JAXA to launch eighth HTV space station cargo mission in September

Japan’s eighth H-2 Transfer Vehicle, seen here, is being prepared for launch from the Tanegashima Space Center on Sept. 10 with supplies and experiments for the International Space Station. Credit: JAXA

Japan’s eighth resupply mission to the International Space Station is set for liftoff Sept. 10 with another batch of upgraded batteries, crew provisions and experiments for the orbiting research lab, the country’s space agency announced Monday.

The eighth H-2 Transfer Vehicle will blast off on top of an H-2B rocket from the Tanegashima Space Center, located on Tanegashima Island near the southwestern extent of Japan’s main islands.

Liftoff is set for 2133 GMT (5:33 p.m. EDT) on Sept. 10, or 6:33 a.m. Japan Standard Time on Sept. 11, according to the Japan Aerospace Exploration Agency. The HTV will arrive at the space station Sept. 14, assuming an on-time launch.

The automated cargo freighter will carry more than 7,700 pounds — about 3.5 metric tons — of supplies and experiments to the space station, JAXA said. That figure does not include support hardware used to mount the HTV’s payloads inside the spacecraft for the journey into space.

The HTV is the largest supply ship currently flying to the space station. JAXA developed the HTV and its H-2B carrier rocket to help pay for Japan’s share of the space station’s operating costs.

Nicknamed Kounotori, which means “white stork” in Japanese, the cargo freighter measures about 33 feet (10 meters) long and about 14 feet (4.4 meters) in diameter. The Kounotori 8 mission will be the eighth flight by an HTV supply ship since Japan launched the first HTV spacecraft in September 2009.

File photo of a Japanese H-2B rocket lifting off from Tanegashima with an HTV supply ship. Credit: JAXA

The HTV mission set for launch in September will carry six lithium-ion batteries to the space station to upgrade the orbiting research lab’s external power system. The station’s robotic arm, with the help of astronauts on two spacewalks later this year, will remove aging nickel-hydrogen batteries from a section of the station’s outboard truss and replace them with the new, higher-capacity lithium-ion batteries.

The International Space Station has four power modules — two on each end of the station’s truss backbone — with solar arrays that span 240 feet (73 meters) tip-to-tip. The solar wings charge batteries that keep the space station’s systems powered during the night portion of each 90-minute orbit around Earth.

Twelve batteries were delivered to the station on the sixth and seventh HTV missions, and a final batch of six lithium-ion batteries will launch on the ninth HTV mission next year.

The Kounotori 8 mission is also carrying food, fresh drinking water, and a high-pressure gas tank to recharge the space station’s internal atmosphere with oxygen and nitrogen.

The HTV will also deliver experiments to the space station.

One of the experiments will demonstrate a high-speed satellite laser communications system developed by JAXA and Sony Computer Science Laboratories. The technology demonstrator will be mounted on an experiment platform outside the space station’s Japanese Kibo laboratory module to test out a laser link with a ground station, which can accommodate higher-bandwidth communications than radio systems.

Japan’s Hourglass experiment is also set for launch on the eighth HTV mission to help scientists investigate the behavior of soil and rock particles under low gravity, simulating the conditions future probes might encounter on a small planet or asteroid.

A science rack to host cellular biology experiments will also fly to the space station on the Kounotori 8 spacecraft, along with three CubeSats to be deployed from the station’s Japanese robotic arm.

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