China launches Tiangong-2 space laboratory into orbit
On Thursday, Sept. 15, China successfully launched a Long March 2F rocket carrying the country’s second space lab – Tiangong-2 (meaning “Heavenly Palace” in Chinese). Liftoff took place at 10:04 p.m. local time (14:04 GMT; 10:04 a.m. EDT) from Launch Area 4 at the Jiuquan Satellite Launch Center, located in China’s Gansu Province.
The launch, originally targeted for 2014, was delayed several times. More recently, the mission was set for Sept. 13; however, it was postponed one more time, most likely due to the Aug. 31, 2016, suspected launch failure of Long March 4C with the Gaofen-10 satellite. Finally, the liftoff was rescheduled to Sept. 15 with a launch window extending until Sept. 20.
Thursday’s flight concludes a three-month long launch campaign, which commenced on July 9 with the arrival of Tiangong-2 at Jiuquan. The booster was shipped to the center nearly one month later, starting a busy month of pre-launch tests and checkouts. The fully assembled launch vehicle, with the space laboratory atop of it, encapsulated in the payload fairing, was rolled out to the launch site on Sept. 9.
Thundering off from the launch pad, the Long March 2F started its short vertical ascent. It was powered by the first stage’s cluster of four YF-20B engines and four strap-on boosters, each fitted with one YF-20B engine. After the brief climb, the rocket turned southeasterly, heading over mainland China, toward the South China Sea.
The quartet of strap-on boosters that provided additional thrust during the initial phase of the flight were jettisoned slightly more than two-and-a-half minutes after liftoff. About 5 seconds later, the rocket’s first stage burned out and was separated. Shortly after, 2 minutes, 30 seconds into the flight, the payload fairing detached from the launch vehicle, leaving Tiangong-2 exposed for the rest of the launch.
Afterward, the second stage assumed control over the flight, accelerating the launch vehicle via a single YF-24B engine for about 7 minutes.
Tiangong-2 was released from the second stage at nearly 10 minutes into the flight. Then the space laboratory deployed its power-generating solar arrays to start its cruise in low-Earth orbit at an altitude of 244 miles (393 kilometers).
Tiangong-2 was launched into orbit with the aim to test technology for the country’s future space station. The lab will be used to conduct various experiments in the field of aerospace medicine, space sciences, on-orbit maintenance, and space station technologies.
Overall, the space lab carries a total of 14 mission and experiment packages including the world’s first-ever-in-space cold atomic fountain clock and the space-Earth quantum key distribution and laser communications experiment. It is capable of receiving manned capsules and automated cargo spacecraft, and it will also be employed as a test platform for systems and processes for mid-term space stays and refueling in space.
The space laboratory 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 taikonauts for up to 30 days. The module is similar in size to its predecessor Tiangong-1 as it was initially planned to be used as a backup for the first laboratory.
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. Unlike its predecessor, Tiangong-2 is equipped with a robotic arm, supporting various activities like attaching modules and scientific containers to the laboratory.
It was considered that Tiangong-2 would be larger than Tiangong-1, having a length of 47 feet (14.4 meters) and weighing 20 metric tons, and would be fitted with two docking ports instead of one like in the previous module. However, because China decided to not to re-design its space laboratory, Tiangong-2 is similar in size to the country’s first space lab and has only one port, disallowing simultaneous docking of one crewed ship and one cargo craft.
Together with Tiangong-2, a small satellite named Banxing-2 (BX-2) was also launched on Thursday’s mission. The satellite, weighing about 88 pounds (40 kilograms), is equipped with a 25-megapixel camera that will take pictures of the space lab in orbit.
Launching Tiangong-2 into space is an important step for China toward building its own permanent space station, as it will enable testing key technologies before sending a larger module into orbit. 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.
China’s future space station is expected to be built sometime between 2018 and 2022. The 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.
The country’s previous space laboratory, 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 2013 when the Shenzhou-10 spacecraft transported another trio of taikonauts. In addition to scientific experiments, the crew taught a physics lesson to Chinese students via live television while on board the lab.
In March 2016, it was reported that Tiangong-1 started to descend gradually and, in several months’ time, the module is expected to burn up in the atmosphere. However, 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, which was 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 the 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 with one YF-24B engine. During the flight, this stage burns for about five minutes.
Thursday’s launch was the 236th flight of the Long March rocket and the 14th orbital mission conducted by China this year. The 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 without any prior notice; therefore, an unexpected liftoff could also be carried out soon.
Video courtesy of SciNews
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