Houston – A key US space shuttle launch schedule is back in the balance this week following a last-minute postponement of a planned spacewalk to help grapple a Chinese space laboratory with the International Space Station.
With no clear window for launching the shuttle Discovery this month, the National Aeronautics and Space Administration made the temporary delay and another unscheduled attempt to attach the space station’s $5 billion lab, Tiangong-1, the China mission’s prime consideration, said NASA spokesperson Beth Dickey on Monday.
Discovery had been scheduled to fly to the space station with a crew of seven on 5 May, then come back for launch in late May or early June, with Atlantis set to take over the ride in June, NASA said.
The mission was put on hold pending the launch of Tiangong-1, which first made its flight to the orbiting outpost in September. It was poised for liftoff on Saturday at 12.20pm EST (1620 GMT), but was ultimately postponed because of a separate technical problem, said Chang Kai, spokesman for the China Aerospace Science and Technology Corporation.
Chang said the problem involved a small, meteoroid that passed over the Tiangong-1 while the spacecraft was in orbit. In general, Chang said, orbital debris poses “minimal” risk to astronauts, but it can nevertheless be an “opportunity for us to learn about the [spacecraft’s] orientation”. In this case, Chang said, the mission management team opted to investigate the problem further. The team then deferred the launch until Tuesday.
Flight controllers initially pushed the Tiangong-1’s flight into orbit by “sending [it] intentionally,” Dickey said, but it only accomplished about a third of its intended orbit. The spacecraft has since been re-orbiting and making slow dives toward the Earth.
Chinese astronauts Jiang Yang (centre) and Jing Haipeng pose for a portrait in the Shenzhou-10 Shenzhou spacecraft after completing the Shenzhou-11 mission aboard a Shenzhou-11 rocket launch on Sunday, 17 September 2005. Photograph: Zhang Den-li/Xinhua/Corbis via Getty Images
Shuttle flight director Christer Fuglesang said the crew will be prepared if the spacecraft surges back into orbit in the coming days.
A crew attempt to attach the station’s lab to the end of a tether at about 7.40am EDT on Tuesday could also push the planned return date to at least 20 May, Dickey said.
The next scheduled launch attempt could also occur on the weekend. If that target is met, it would give the shuttle time to dock with the space station in June. A weekend launch would also accommodate a four-day gap between Atlantis’ next launch and the shuttle’s planned orbital delivery of a Canadian payload.
Discovery will be just one of two shuttle missions this year. The other mission is Atlantis’ launch, according to current schedules, on 25 June. In all, seven space shuttle flights are planned in 2019, a decelerating rate of missions after 10 years of continuous shuttle operation.
Discovery, with its 11-member crew including commander Christopher Ferguson, will dock with the space station at 6.43pm EDT on Thursday to deliver 13,000kg of supplies and equipment, including a new pallet that will double the station’s inventory of spare parts. Ferguson and the rest of the crew are scheduled to spend five days docked at the station.