Artist illustration of a Shenzhou spacecraft (left) docked with a Tiangong space lab (right).
China’s second space lab popped up unexpectedly, the direction of the Earth this month, just two months after its predecessor crashed uncontrolled into our planet’s atmosphere.
The uncrewed Tiangong-2 vehicle decreased approximately 59 miles (95 km), two weeks ago, then shot back to the previous 242-mile high (390 km) orbit on June 22, according to Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics, which keeps tabs on many of the more interesting objects circling Earth.
The first dive prompted some speculation that China was preparing to deorbit Tiangong-2. But the boost back up to 242 km suggests that something else is going on, McDowell said. (The proof of these maneuvers is derived from the tracking data collected by the U.S. government.) [Chinese Tiangong-2 Space Lab Mission in Pictures]
McDowell thinks that China introduced this month, the exercise is mainly to the collection of additional data about the subsystems aboard the Tiangong-2, which was launched in September 2016. Many of these subsystems — in particular in the area of the lab, and bow thrusters — is likely to be included in the space of the nation strives to be up and running in an orbit around the Earth by 2022, he said.
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Chinese officials, therefore, probably “do you want more baseline on how the propulsion system works, how reliable it is, how well it works after two years in space,” said McDowell Space.com.
As a kind of bonus, McDowell added, the fall-and-rise move also used on a number of fuel, making Tiangong-2 any re-entry less explosive.
It is unclear when that re-entry will occur. But this month’s maneuvers demonstrate that China still has control over the 9.5 tons (8.6 tonnes, Tiangong-2, so they can map out a focused deorbiting campaign now, if they wished, McDowell emphasized.
It only takes a few hundred kilograms of fuel to deorbit Tiangong-2 in such a manner, ” he said. And McDowell estimates that the space lab will probably still be about 700 kg (1,540 lbs.) of the original 1,000 kg (2,200 lbs.) fuel load left.
Tiangong-1’s demise, on the other hand, was not checked. China’s first space lab launched in September 2011 and hosted two visiting astronaut crews, in June 2012 and June 2013. The transfer of data between Tiangong-1 and the handlers stopped in March 2016, and the huge vessel fell to the Earth on April 1 of this year, break apart and burn up over the southern Pacific Ocean.
The re-entry caused no reports of injuries or damage to the structure. By coincidence, Tiangong-1 came back to the Earth in the vicinity of “Point Nemo,” the isolated stretch of water where the mission planners try to dump their dying or abandoned spaceship.
The two Tiangong craft, whose Mandarin name translates as “heavenly palace,” both of which are designed to help China master the skills that are necessary for the construction of a full-on space station, such as rendez-vous and docking technology. Tiangong-2 hosted a set of astronauts, in October-November 2016, and served as the basis for several robotic refueling demonstrations, the last of which wrapped in September 2017.
Tiangong-2 was in a sort of hibernation since then, the run of small engine once every few months to preserve his job. That maneuvers, and this month’s fall and rise, show that China still has control over the space lab. But Tiangong-2 s-handlers must not this state of affairs for granted, McDowell said.
“What you don’t want them to do is the wrong lesson from this test, that is, ‘Oh, it works fine; we keep in a job for three years and then discover two years from now that something breaks, and it is not fine anymore,” he said.
Originally published on Space.com.