An H-2B rocket blasted off from Tanegashima Launch Center in Japan early this morning, carrying the sixth H-2 Transfer Vehicle on its climb to the International Space Station. Alas, there was not much time to add cargo following the loss of the last Progress, and HTV cannot make up for the lost propellant (as with the retirement of ATV, Progress is the only means of refueling Zvezda), but it adds a lot of comfortable margin into the stores on board ISS.
The principle payload of this mission is a six new lithium-ion batteries carried in Kounotori-6’s unpressurized payload bay. These large batteries are intended to replace the batteries in the power supply of the US segment. A s they are lighter and more efficient, one battery is able to do the job of two of the old batteries. Later on, they will be extracted from Kounotori-6 and subsequently installed in the S4 truss via Dextre, the “Canada Hand” Special Purpose Dextrous Manipulator. Dextre will also pull nine of the old batteries and stow them aboard Kounotori-6 for disposal when the spacecraft deliberately deorbits after its mission. Additional batteries will go up on the next three HTV flights.
The pressurized compartment will deliver food, water, clothing, tools, spare parts, research payloads, computer equipment, spacesuit components, a small amount of Russian cargo, a new radiation monitoring experiment, some new cameras to be mounted outside the Kibo module later on for JAXA, fresh CO2 scrubber components, and a dozen CubeSats, which will be deployed over the next few months via the Kibo module’s airlock and NanoRack dispenser.
After the spacecraft is finished with its ISS mission, it will continue to perform science; just like Cygnus, scientists have found ways to make use of the spacecraft after its primary mission is complete. In this case, JAXA will be testing deployment of an electrodynamic tether to see how practical this could be for cheaply altering a spacecraft’s orbit. If it works, such a system could be placed on future spacecraft to ensure their disposal at the end of their missions. Right now, most dead spacecraft simply remain in orbit until they fall naturally, and this presents a debris hazard.