[Xinhua] Chinese scientists say goodbye to Tiangong-2, expecting space station

[Orionid]

Chinese scientists say goodbye to Tiangong-2, expecting space station
Source: Xinhua| 2019-07-19 23:58:27|Editor: yan by Xinhua writer Yu Fei

BEIJING, July 19 (Xinhua) -- After helping scientists complete many significant experiments such as growing rice and vegetables in space, observing the strongest explosions in the universe and setting up the most precise clock in space, China's first space lab Tiangong-2 ended its mission and reentered the atmosphere under control Friday night (Beijing Time).

With deep attachment, Chinese scientists recalled the experience of participating in the design and implementation of the space experiments on Tiangong-2 and also looked forward to more frontier research on China's future space station.

VALUABLE OPPORTUNITY

Zheng Huiqiong, a researcher at the Institute of Plant Physiology and Ecology of the Chinese Academy of Sciences (CAS), still remembered how she nervously waited for astronauts in November 2016 to bring back a small box containing the Arabidopsis thaliana, a kind of vegetable, which had grown on Tiangong-2 for about 50 days.

As the lead scientist of the experiment, she was the first one to see the plant with a little blossom.

"That was an unparalleled exciting moment," Zheng said.

Zheng's team put seeds of Arabidopsis thaliana and rice in the space lab to allow them to complete the growth process from seeds to producing seeds in space, the first such experiment carried out by Chinese scientists.

From the small box brought back by astronauts, the team harvested nine seeds, which have generated the fourth generation on Earth.

"The Tiangong-2 mission was our first opportunity to carry out a long-term plant experiment in space. This experiment is significant because growing grains and vegetable will be a necessity if humans want to leave the earth and have long-term survival and travel in space," Zheng said.

Many interesting and important discoveries have been made in the experiments of Tiangong-2.

"We found that plants grow slower in space than on Earth and blossom later. However, they live longer in space than on Earth. The lifespan of Arabidopsis thaliana in space was about twice as long as on Earth. We believe that the genes related to aging change in space," Zheng said.

"If we find the method to regulate the growth of plants, we could postpone the blooming of vegetables to make them grow more leaves and accelerate the blooming of rice to make them seed as soon as possible. Therefore, we can use the limited resources in space to maximize crop yields. The research can also find its application back on Earth," said Zheng.

Yin Dekui, a researcher at the Shanghai Institute of Technical Physics of CAS, recalled that his team had tested the multi-angle wide-band imaging spectrometer on an airplane before the instrument was installed on Tiangong-2. The researchers persisted in the bumpy plane for the experiment while vomiting.

Zhang Yunhua, a researcher at the National Space Science Center of CAS, said Tiangong-2 has provided valuable opportunities for Chinese scientists to test their new technologies and methods. His team developed a three-dimensional microwave altimeter and tested it on Tiangong-2 to improve China's ocean observation capability.

EXPECTATIONS

The success of the Tiangong-2 mission has ushered in the era of building China's space station, which is expected to be completed around 2022.

Weighing 66 tonnes, the Tiangong space station will be a T shape with the Tianhe core module at the center and the Wentian and Mengtian lab capsules on each side.

The station, orbiting 340 to 450 kilometers above the Earth's surface, could be enlarged to 180 tonnes if required and accommodate three to six astronauts. It is designed to last at least 10 years, but this could be prolonged through in-orbit maintenance, Zhou Jianping, chief designer of China's manned space program, has said.

Sixteen experiment racks will be installed on the space station to support hundreds of space research projects, according to the Technology and Engineering Center for Space Utilization of CAS.

"The experiments on Tiangong-2 have laid the foundation for further experiments and research on the space station.
For instance, we want to study the intrinsic mechanism of prolonged life in space," said Zheng.

"Although Tiangong-2 was successful, we still have many regrets about the experiment. We hope to have the opportunity to do better on the space station," She added.

Tiangong-2 tested the first-ever cold atom clock in space, which was so accurate that it would only lose one second in 30 million years. The development of the clock would have a far-reaching impact on the deep space exploration, basic physical research and precision measurement, according to its developers from the Shanghai Institute of Optics and Fine Mechanics of CAS.

China's space station will carry a hydrogen clock, a cold atomic clock and an optical clock to establish a high-precision time and frequency system. The margin of error of the system would be less than one second every 3 billion years.

Zhang Lixian, a designer of the experiment racks of China's space station, said each rack could be regarded as a lab moved into space and capable of supporting various cutting-edge space experiments.

For instance, one rack is equipped with an automatic mechanical arm with an operational accuracy of better than five microns, which could support experiments at the level of the nucleus, according to Zhang.

FOR BOTH CHINA AND WORLD

A total of 37 TB data obtained by Tiangong-2 has been provided to customers for earth observation projects in both China and abroad, according to the Technology and Engineering Center for Space Utilization of CAS.

Li Xuan, an engineer from the center, said China and Thailand have cooperated to develop an agricultural big data platform by using Tiangong-2 data, which helps Thai farmers monitor crop growth, pests and diseases.

A device named POLAR, developed by scientists from China, Switzerland and Poland, was installed atop Tiangong-2 to search for gamma-ray bursts, the strongest explosions in the universe.

The in-depth cooperation between Chinese and European scientists in the experiment is an important breakthrough, laying a solid foundation for more and deeper cooperation between the two sides in the future, said Sun Jianchao, a member of the team from the High Energy Physics Institute of CAS.

Scientists from China, Switzerland, Germany and Poland plan to continue their cooperation and develop the POLAR-2 on China's space station, which is expected to contribute to the study on questions like the formation of black holes, said Sun.

China is seeking international collaboration in experiments on the space station to promote sustainable global development and cooperation.

Nine scientific experiments involving 23 entities from 17 countries have been accepted to be conducted onboard China's space station, the United Nations and China announced recently.

Source: http://www.xinhuanet.com/english/2019-07/19/c_138241520.htm

[Orionid]

China’s Tiangong-2 space lab reenters over South Pacific
by Andrew Jones — July 19, 2019 [SN]


Onboard footage from Tiangong-2 during re-entry. Credit: CCTV/framegrab

HELSINKI — China carried out the controlled deorbiting of its Tiangong-2 space lab into the South Pacific, the China Manned Space Engineering Office (CMSEO) announced Friday.

The 8.6-metric-ton Tiangong-2 (‘Heavenly Palace 2’) reentered over the South Pacific Ocean Uninhabited Area at 9:06 a.m. Eastern using its own propulsion, following an engine burn 10 a.m. July 18 to lower the spacecraft’s perigee. Limited of the event was released shortly after.

CMSEO stated July 13 that it would end the Tiangong-2 mission July 19 Beijing time, in keeping with an announcement in September 2018 that the space lab would be deliberately deorbited this year.

The maneuver follows the high-profile and uncontrolled re-entry of Tiangong-1 in April 2018, having lost contact with and control of the experimental space lab in 2016.

Tiangong-2 was a more advanced version of the Tiangong-1 space lab which launched in 2011. Both were designed as steppingstones for developing and verifying technologies for larger 20-metric-ton modules for the planned Chinese Space Station (CSS), a long-term ambition laid out in 1992.

Tiangong-2 was launched in September 2016 to test advanced life support and refueling and resupply capabilities crucial to maintaining an inhabited space station in low Earth orbit.

The 10.4-meter-long spacecraft hosted two astronauts, Jing Haipeng and Chen Dong, for the vast majority of the 33-day Shenzhou-11 mission in late 2016, which remains China’s both latest and longest human spaceflight mission.

This was followed by the uncrewed Tianzhou-1 cargo mission, launched April 2017, which tested faster rendezvous and docking procedures, refueling in microgravity and further experiments.


A view of Tiangong-2 (below) docked with Shenzhou-11 imaged by Banxing-2. Credit: Chinese Academy of Sciences
 
Space station plans delayed

With the end of the Tiangong-2 China enters a period without a spacecraft capable of hosting human spaceflight missions for the first time since 2011.

China planned to launch the ‘Tianhe’ core module of the CSS in 2018, but the launch failure of second Long March 5 rocket in July 2017 has led to postponement of the test launch of the Long March 5B, a variant designed for carrying the space station modules into low Earth orbit.

An official with the China Aerospace Science and Technology Corporation, the country’s main space contractor, told state-run Xinhua News Agency in January that a mission dress rehearsal involving a non-flight model of the rocket and the CSS core module would be carried out at Wenchang at the end of 2019. This would be part of preparations for the test flight of the Long March 5B which, if successful, would lead to the launch of the first CSS module in 2020.

However, the requisite return-to-flight of the Long March 5 — then slated for mid-July — appears to have slipped, with no indication from China as to when the launch will take place. The delay also means that the Chang’e-5 lunar sample return mission will almost certainly not take place in late 2019 as planned.

According to plans released by China, the 60-100-metric-ton Chinese Space Station will consist of a core module and two experiment modules. It is expected to be completed by ‘around 2022’ and will be capable of hosting three astronauts for long durations and up to six during crew turnover. It will be joined by a co-orbiting Hubble-class space telescope that can dock for propellant supply, maintenance and repairs.

In June six experiments were selected for a place aboard the future Chinese Space Station through a joint international cooperation initiative, with three more receiving conditional acceptance.

Source: https://spacenews.com/chinas-tiangong-2-space-lab-reenters-over-south-pacific/

[Orionid]

Chinese space station testbed ends mission with controlled re-entry
July 19, 2019 Stephen Clark [SFN]




A prototype space lab module for China’s planned space station re-entered the atmosphere over the South Pacific Ocean Friday to end a nearly three-year mission that included a visit from Chinese astronauts and an in-orbit refueling demonstration.

The 34.1-foot-long (10.4-meter) Tiangong 2 module plunged into Earth’s atmosphere at 1306 GMT (9:06 a.m. EDT) Friday and burned up as intended. Debris from the spacecraft fell in a remote zone of the South Pacific Ocean between New Zealand and Chile.

Chinese officials guided the Tiangong 2 spacecraft for a targeted re-entry after the module’s predecessor, Tiangong 1, fell out of orbit in an uncontrolled manner last year, raising concerns about falling space junk.

According to China’s state-run Xinhua news agency, the guided re-entry of Tiangong 2 “demonstrates that China sticks firmly to its international duties and keeps its promise of peaceful and scientific use of space resources,” said Zhu Congpeng, chief designer of Tiangong 2 from the China Academy of Space Technology.

Tiangong 2 was not designed to survive re-entry, and video captured from a camera on-board the spacecraft showed a cloud of ionized gas building up around the module as it fell into the atmosphere. Then the communications signal cut off, as expected, before Tiangong 2 broke apart.

Unlike the situation with Tiangong 1, Chinese space officials elected to deorbit Tiangong 2 when it still had enough propellant to safely maneuver back into the atmosphere.

“Although Tiangong 2 had been in operation nearly one year longer than its designed lifespan, its platform and payloads functioned stably and soundly, and the propellant it carried was still sufficient to support its flight in orbit for another several years,” Zhu said, according to Xinhua. “It’s hard to say goodbye to Tiangong 2, but considering reliability- and safety-related factors, we have to drive it out of orbit now.”

“To let Tiangong 2 ‘retire’ by choice is to ensure the absolute safety of its departure,” Zhu said.

Two rocket firings by Tiangong 2’s propulsion system lowered the spacecraft from its operational orbit roughly 235 miles (380 kilometers) above Earth, beginning Thursday. After an initial maneuver Thursday to move into an elliptical orbit, Tiangong 2 fired its thrusters again Friday for a final deorbit burn, committing the module to re-entry, according to the China Manned Space Engineering Office.

Designed for a two-year lifetime, the bus-sized Tiangong 2 space lab launched Sept. 15, 2016, on top of a Long March 2F rocket from the Jiuquan space base in northwestern China.

The Shenzhou 11 spacecraft and its two-man crew docked with Tiangong 2 a month later for a four-week stay, the longest Chinese human space mission to date.

After Shenzhou 11’s departure, China launched a robotic refueling freighter in April 17 to dock with Tiangong 2 and carry out a series of tests to demonstrate capabilities for servicing China’s future space station.

The Tianzhou 1 refueling spacecraft docked with Tiangong 2 three times, testing maneuvers needed for fast-track rendezvous profiles that will allow future cargo and resupply freighters to dock with China’s planned space station as little as six hours after launch.

While attached to Tiangong 2, the Tianzhou 1 spacecraft pumped rocket fuel and oxidizer into the Tiangong 2 space lab, the first such in-space refueling activity in China’s human spaceflight program.

The Tiangong 2 spacecraft measured about 34.1 feet (10.4 meters) long, and its main body has a diameter of about 11 feet (3.35 meters). The space lab’s two solar array wings extend to a span of about 60 feet (18.4 meters) tip-to-tip.

Tiangong 2 hosted dozens of additional scientific and engineering experiments, including an ultra-precise cold atomic clock that could aid future space-based navigation systems, and a gamma-ray burst detector developed jointly by Chinese and European scientists.

The grounding of China’s heavy-lift Long March 5 rocket has raised doubts over the schedule for the launch of the first element of multi-module Chinese space station. China is building the space station’s core module for launch on a Long March 5 booster, but the rocket has not launched since suffering a failure in July 2017.

Several missions are ahead of the Chinese space station in the Long March 5 manifest, once the rocket resumes operations. They include the launch of a large Chinese communications satellite, the Chang’e 5 lunar sample return mission, and a test flight of the Long March 5B variant, which is configured for missions to haul space station modules into orbit.

A Chinese Mars lander is also supposed to take off on a Long March rocket in July 2020.

China says the human-tended orbiting complex should be completed by around 2022.

Chinese officials announced last month the selection of international science teams to provide at least six research instruments to fly on the Chinese space station. Another three science payloads received conditional acceptance to fly on the Chinese station.

The nine instrument teams selected to fly their experiments and sensors on the Chinese space station include membership from Belgium, China, France, Germany, India, Italy, Japan, Kenya, the Netherlands, Norway, Mexico, Poland, Peru, Russian Federation, Saudi Arabia, Spain and Switzerland.

Source: https://spaceflightnow.com/2019/07/19/chinese-space-station-testbed-ends-mission-with-controlled-re-entry/