Japan’s unmanned freighter spacecraft, HTV-3, was successfully detached from the International Space Station as planned on 12 September at 1550 GMT . However, shortly after detaching and gently moving away, the craft made an unexpected emergency retreat from the station – a mode of operation that is only supposed to kick in when the on-board systems indicate that the craft is in danger of striking the space station. Engineers from the Japanese space agency JAXA are now investigating why this Abort Control Unit (ACU) procedure was triggered. The craft is expected to be de-orbited after an engine firing at 0451 GMT on 14 September to a safe burn up re-entry, with any remainng debris planned to land in the Pacific.
JAXA’s HTV-3 during its earlier berthing manoeuvre with the International Space Station. Courtesy: NASA