Tag Archives: HTV

HTV space debris experiment is a bust — better luck next time!

The Kuonotori-6, the latest H2 Transfer Vehicle (HTV) to fly from Japan to the ISS, also carried a space debris experiment.  After completing its cargo delivering mission (including delivery of the first set of new batteries for the station’s main power system) and loading up with trash and an old set of batteries, it departed the ISS on January 27.  Not ones to waste a good opportunity, JAXA had equipped it to carry out additional experiments between undocking and its ultimate fiery demise.  For this mission, it carried an electrodynamic tether which, when fully unspooled, would stretch half a mile into space, to test the effectiveness of such a system in passively lowering a satellite’s orbit purely through interaction with the Earth’s ionosphere.

Unfortunately, they ran into problems during deployment.  First, one of the four bolts holding the tether’s counterweight failed to separate on the first try.  On a second attempt, telemetry indicated that the bolt finally separated, but the tether still would not deploy.  Possibly the bolt did not fully separate, or possibly there was some other problem with the mechanism; JAXA engineers will certainly be closely evaluating the telemetry before attempting the experiment again.  One thing is certain: they will not be attempting again with this spacecraft: after abandoning the tether deployment, Kuonotori-6 was deorbited last Sunday, making a self-destructive reentry over the South Pacific.

Still, Japanese engineers do not tend to give up easily, so I expect they will try again.  They’ll have additional opportunities: although HTV does not fly as often as many other ISS cargo ships, it is vital for delivery of the new batteries for the main power system.  New methods for disposal of space hardware is urgently needed; if successful, tethers like this could even be used on things like spent rocket stages, since it is a completely passive system and doesn’t weigh much.  Being able to dispose of spent hardware means it doesn’t stick around to contribute to the growing problem of space debris.

So here’s hoping they can get it working next time!


1 Comment

Filed under Space

Cargo to the ISS resumes, with HTV “Kounotori-6”

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.

Leave a comment

Filed under Space

The fifth White Stork spreads its wings

Kounotori-5, the fifth HTV (H-2B Transfer Vehicle), has been launched from Tanegashima Space Center in Japan, aboard the beefy H-2B rocket, loaded with supplies for the ISS that are now even more critical than ever after a string of failures grounded the other two large cargo vehicles.  (Progress made a successful run, but is smaller, with a standard Soyuz cone-and-drogue hatch.  HTV, Cygnus, and Dragon all make use of the spacious Common Berthing Adapters instead, allowing delivery of larger payloads.)  Kounotori-5 is now making its gradual approach to the ISS, and in a couple of days will be captured by the SSRMS, operated by JAXA astronaut Kimiya Yui, and berthed at the station.  It will be the last flight to the US segment until Cygnus returns to flight in December.

HTV is scheduled to make another flight next year, and then fly about annually thereafter.  By internal volume, it is one of the largest of the cargo vehicles that flies to the ISS (second largest by pressurized volume, largest by upmass — ATV was larger in both but is no longer flying, and of course Shuttle won overall), and this flight alone will deliver enough consumables to keep the ISS operating into next year even if there is no more resupply in 2015.  Like Dragon, it is able to carry unpressurized payloads as well, but unfortunately not as much space is devoted to this unpressurized section and so it cannot duplicate Dragon’s role in delivering the new docking adapters.  But its mission is nevertheless critical.

Congratulations on an excellent launch, Japan!

Both HTV and the H-2B rocket are joint efforts between JAXA and their manufacturer, Mitsubishi Heavy Industries.

Leave a comment

Filed under Space