China will launch on Thursday, Sept. 15, its second space laboratory called Tiangong 2 (meaning “Heavenly Palace”), to test technology for the country’s future space station. The orbital lab will ride into space atop a Long March 2F rocket, lifting off from Launch Area 4 at the Jiuquan Satellite Launch Center, located in China’s Gansu Province.
The exact date of the liftoff has not been disclosed yet. Chinese state-run media only inform that the launch window extends until Sept. 20. The launch of the mission was initially targeted for 2014, however it was postponed several times. More recently, China scheduled the liftoff for Sept. 13, but it was further delayed due to unknown reasons. It could be caused by the suspected launch failure of Long March 4C with Gaofen-10 satellite on Aug. 31, 2016 but it still remains a target of speculation.
The mission campaign started in July with the arrival of Tiangong 2 at the center on July 9. It was transported from Beijing to Jiuquan by rail. Due to the fact that the space lab was shipped to the launch center in parts, immediately after arrival, the spacecraft was assembled and underwent initial checkouts.
The Long March 2F booster departed by train from Beijing on Aug. 3 to arrive at Jiuquan three days later. Next, the stages of the rocket passed electrical and autonomous tests before the launcher could be fully assembled.
August was a busy month for engineers due to intensive set of tests and checkouts of the spacecraft and the rocket. Afterwards, the laboratory was mated to payload adapter and encapsulated in the payload fairing. Then, the stack was installed onto the integrated launch vehicle.
The rocket, carrying the encapsulated Tiangong 2, was rolled out to the launch pad on Sept. 9. It took 90 minutes to deliver it from the assembling center to the launch site.
"The completion of the transfer signals that the space lab Tiangong 2 mission has entered its launching stage," the office of China's manned space program said in a press release.
Awaiting its Sept. 15 launch, the rocket now undergoes final tests and will be fueled with propellant before the planned liftoff.
Tiangong 2 is similar in size to its predecessor Tiangong 1 as it was originally intended to serve as a backup for the first laboratory. It is 34 feet (10.4 meters) long and has a diameter of 11 feet (3.35 meters). With a mass of 8.5 metric tons, it can accommodate two astronauts for up to 30 days. The lab will be inserted into a low-Earth orbit at an altitude of 244 miles (393 kilometers).
|Tiangong 2 space lab in June 2016. Photo Credit: CCTV|
Previous rumors that Tiangong 2 will be larger than the first lab module, weighing 20 metric tons and having 47 feet (14.4 meters) in length, were not confirmed by Chinese officials. Thus, due to the fact that China has not decided to re-design its space laboratory, Tiangong 2 will also have one docking port like its predecessor, although it was expected that the new module will be fitted with an additional port allowing simultaneous docking of one crewed ship and one cargo craft.
Tiangong 2 is composed of two main compartments: the “experiment cabin” which, as the name suggests, allows for the conducting of experiments in space and also serves as the crew’s quarters; and the “resource cabin” which houses the solar panels, engines, and other equipment.
The laboratory will be used to conduct various experiments in the field of aerospace medicine, space sciences, on-orbit maintenance, and space station technologies. It is capable of receiving manned and cargo spacecraft, and it will be also employed as a test platform for systems and processes for mid-term space stays and refueling in space.
In October 2016, Tiangong 2 will be visited by the crewed Shenzhou 11 spacecraft. The arriving crew will enter the module to live there and carry out experiments. In April 2017, the new Tianzhou 1 cargo ship is planned to dock with the laboratory, delivering fuel, and supplies.
Along with Tiangong 2, a small satellite named Banxing-2 (BX-2) will also piggyback on the mission. The satellite, equipped with a 25-megapixel camera, will take pictures of the space lab in orbit.
Launching Tiangong 2 into space is an important step for China towards building its own permanent space station, as it will enable testing key technologies before sending a larger module into orbit. The station is expected to be built sometime between 2018 and 2022. First module of the future orbital outpost, called Tiangong 3, will include a laboratory with integrated modular racks for storing scientific equipment. It will also have five docking ports and a robotic arm.
China’s first space lab, Tiangong 1, was launched in September 2011. In June 2012, three Chinese astronauts inside the Shenzhou 9 spacecraft docked with it for the first time. Tiangong 1 was visited in June of 2013 when the Shenzhou 10 spacecraft transported another trio of astronauts. In addition to scientific experiments, the crew taught a physics lesson to Chinese students via live television while on board the lab.
The China Manned Space Engineering Office reported in March 2016 that Tiangong 1 started to descend gradually and, in several months’ time, the module is expected to burn up in the atmosphere. As control over the spacecraft was lost, it will undergo an uncontrolled re-entry; thus, the exact time and place of its fall to Earth are currently difficult to determine.
The 170-feet (52 meters) tall Long March 2F rocket that will be used to launch Tiangong 2 into space, is 11 feet (3.35 meters) in diameter and weighs around 464 metric tons. It is a two-stage rocket capable of sending up to 8.4 metric tons into a low-Earth orbit (LEO). For Thursday’s launch, the rocket will fly in 2F/G configuration that was specially designed to launch space laboratories such as Tiangong. It features a launch escape system and has a larger fairing to accommodate larger payloads.
The rocket’s first stage is 78 feet (23.7 meters) long and 11 feet (3.35 meters) in diameter. This stage is fitted with four YF-20B engines burning for two minutes and 46 seconds. Four strap-on boosters are attached to the first stage, powered by one YF-20B engine each.
The second stage – 44-feet (13.5 meters) long and 11 feet (3.35 meters) in diameter – is equipped in one YF-24B engine. During the flight, this stage burns for about five minutes.
Thursday’s launch will be the 236th flight of the Long March rocket and the 14th orbital mission conducted by China this year. Next Chinese missions are currently scheduled for October, when the country plans to conduct a maiden flight of its Long March 5 booster and will perform another launch of a Long March 2F rocket, carrying the Shenzhou 11 manned spacecraft. However, China launches many missions unannounced, therefore an unexpected liftoff could be also carried out in September.