The two astronauts, commander and three-flight veteran Jing Haipeng and flight engineer and first-time flyer Chen Dong, were launched to orbit aboard the Shenzhou 11 spacecraft from Jiuquan Satellite Launch Centre on on 19 October. Their spacecraft vehicle successfully docked with the Tiangong 2 space laboratory module on a 380 km Earth orbit on 20 October. The duo spent the next 30 days onboard the orbital station to carry out a series of scientific and engineering experiments, including growing romaine lettuce, observing silkworm cultivation, and releasing a NanoSat Baixing 2.
On 14 November, the search and rescue team at the Siziwang Banner Landing Site in Inner Mongolia conducted a final rehearsal for the recovery of the re-entry capsule and its crew. Weather forecast suggested a favourable condition for the landing. This was the first time that a crewed landing mission was carried out in a winter month, when temperatures drop to below zero degree at the landing site.
The two astronauts vacated the Tiangong 2 module and returned to the Shenzhou 11 vehicle at 12:41 CST (04:41 UTC) on 17 November. The Shenzhou vehicle then undocked with Tiangong 2 to prepare for its re-entry and landing.
The mission control at Beijing Aerospace Command Centre (BACC) issued the command to Shenzhou 11 for initiating its re-entry sequence at 13:11 CST (05:11 UTC) on Friday 18 November.
The re-entry sequence began with the firing of the Shenzhou spacecraft’s manoeuvring thrusters to turn the vehicle 90° in the azimuth direction, before the unoccupied orbital module was jettisoned. The spacecraft then made another 90° turn in the azimuth direction, so that it travelled in a ‘backside first’ position, with its main engine pointing forward towards its orbital motion direction. The final manoeuvre involves the spacecraft raising its backside slightly to create an angle between the spacecraft axis and its motion direction.
The spacecraft then fired its main engines for a two-minute de-orbit burn, reducing its velocity by about 100 m/sec to allow it to enter the re-entry trajectory. The retrofire took place over Southern Africa, while the spacecraft is monitored by the Yuanwang tracking ship off the West African coast and the ground tracking station in Swakopmund, Namibia. The service module of the spacecraft would normally be jettisoned at an altitude of 140 km.
The journey to home took about 45 minutes, during which the re-entry capsule carrying the crew would make an unpowered (but controlled) ballistic descent through the atmosphere with its heat shield protected blunt end pointing forward. After a brief radio communications blackout, the 3.2 metric ton re-entry capsule deployed its parachutes at an altitude of 10,000 m.
At an altitude of 6,000 m, the astronauts’ seats were elevated into a landing position. The 280 kg heat-shield on the bottom of the capsule was jettisoned. At about one metre above the ground, the re-entry capsule would fire its four landing rockets at the bottom to reduce the descent rate to 2—5.5 m/s before touching down.
The Shenzhou 11 re-entry capsule touched down in Inner Mongolia at 13:59 CST (05:59 UTC), at a location some 100 km east of the targeted landing spot inside the landing zone. Even after the capsule had touched down, its flight trajectory was still being calculated in order to establish the exact landing location. A search and rescue team consisting of fixed wing aircraft, helicopters, unmanned aerial vehicles, and ground vehicles was deployed to recover the capsule and its crew, but poor visibility at the landing location due to heavy smog led to further delay in finding the capsule.
The rescue crew aboard helicopters finally landed near the Shenzhou 11 capsule some 20 minutes after landing. The two astronauts opened the hatch on the capsule and exited the capsule under the assistance of the rescue crew, concluding their historical 32-day mission. About an hour later, the two space heroes were airlifted by a helicopter to a nearby military airport, where they boarded a military passenger jet to fly to Beijing for medical isolation and examination.
In the meantime, Tiangong 2 continues flying on a 380 km Earth orbit. The next visit to the space laboratory module is expected to take place in April 2017, when it will be refuelled by a Tianzhou cargo resupply ship launched atop a Long March 7 launcher from Wenchang Space Centre on Hainan Island.
(Images: Xinhua, Chinese Internet)