According to mission planners for the International Space Station (ISS), the schedule for today's deorbiting of the first unmanned cargo vehicle of the Japanese space agency may be tweaked a little bit, on account of a large piece of space debris, which is flying too close to the orbital outpost. Original plans had it that the H2 Transfer Vehicle (HTV) would undock from the station at 12:05 pm EDT (1605 GMT), but now experts believe they will keep it on for an extra orbit. This puts the new undock time at around 1:30 pm EDT (1730 GMT), Space reports.

The ground monitoring stations, keeping an eye out for the space debris that risk impacting the station, said that there would be no need for the orbital facility to fire up its thrusters in order to avoid an impact. The space junk, a piece of an old Russian satellite, will pass sufficiently far away not to merit further consideration. However, if the HTV is deorbited at the initially planned time, it may impact the fragment, generating more debris exactly on the orbit that the ISS uses. This is, of course, unacceptable, therefore, scientists are struggling to determine when the best time would be for the HTV departure.

Yesterday and the day before that, ISS flight engineers moved all the supplies out of the cargo freighter into the station, and secured all the residues on the station in place on the module. As it leaves the station, JAXA's first unmanned delivery vehicle will be drawn in by the Earth's gravitational pull, and will be burnt up in the atmosphere, over the Pacific Ocean. “They tracked it for a few days and determined it was going to be outside what we call the pizza box, and that the station will be safe. They just wanted to give HTV the same courtesy,” Kelly Humphries, a spokesperson for NASA, explains.

“HTV-1 is opening up new horizons for JAXA's undertaking of human spaceflight. I like to say that JAXA is now entering a new era,” JAXA's Houston Office Deputy Director, Masazumi Miyake, said before the September 11 launch. “We had an amazing time doing this, we're so happy to have this beautiful vehicle here. We look very [much] forward to going in tomorrow and finding all the supplies that I'm sure you've stored there for us,” Nicole Stott said at 3:47 pm EDT (1947 GMT) on September 18, after completing the HTV-1 capture-and-dock procedures. The HTV is unable to guide itself to a docking port, and therefore needs to be captured via the robotic arm.