H-2B launch
A Japanese H-2B rocket carrying the HTV-5 cargo spacecraft lifts off Aug. 19 from the Tanegashima Space Center. Credit: NASA TV

WASHINGTON — An H-2 rocket successfully launched a Japanese cargo spacecraft carrying more than four tons of supplies and equipment for the International Space Station Aug. 19.

The H-2B rocket lifted off from Japan’s Tanegashima Space Center at 7:50 a.m. Eastern time carrying the fifth H-2 Transfer Vehicle (HTV) spacecraft, releasing the spacecraft into low Earth orbit about fifteen minutes later. The spacecraft is scheduled to arrive at the station Aug. 24.

The spacecraft is carrying about 3.7 metric tons of cargo in its pressurized compartment. That cargo includes supplies for the station’s crew as well as hardware and experiments, including a mouse habitat and electrostatic levitation furnace.

The HTV also carries a number of cubesats that will be deployed from the ISS, 14 of which are Earth imaging spacecraft built by San Francisco-based Planet Labs. The HTV mission brings the total number of spacecraft launched by Planet Labs to 101, although most of those are no longer in orbit. The company lost eight satellites on the SpaceX Falcon 9 launch failure in June, and 28 on an Orbital ATK Antares launch failure last October.

Another commercial payload on the HTV is an external platform developed by Houston-based NanoRacks. That platform, which will be located outside the station’s Kibo module, will provide space for experiments needing access to the space environment.

In addition to the pressurized cargo on the HTV, the spacecraft is carrying nearly one metric ton of unpressurized cargo, including the Calorimetric Electron Telescope astrophysics experiment. That experiment, to be mounted on the exterior of the station, will study high-energy cosmic rays that scientists think could provide insights into dark matter.

The arrival of the HTV will further ease concerns about the station’s supply of food and other consumables that were under strain by a series of cargo mission failures in the last year. The additional cargo on board the HTV will extend station’s supplies through at least the end of the year.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...