China to launch first module of massive space station
Since the Soviet Union launched the first space station, Salyut 1, 50 years ago, humans have lived in a total of 11 such facilities in Earth orbit. China will soon add another to this list. With the basic module of the Chinese space station (CSS) scheduled for launch at the end of April, the culmination of a project initially envisaged by the national government in 1992 is finally entering the construction phase.
Once the central module reaches space, China plans at least 10 more launches of other major modules, as well as crewed and cargo missions, to complete assembly of the station by the end of 2022. At that time, the CSS will join the International Space Station (ISS) as the only fully operational space stations in orbit.
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The 100-ton T-shaped CSS will consist of three main modules: the 18-meter-long central module, called Tianhe (“Harmony of the Heavens”), and two 14.4-meter-long experiment modules, called Wentian (“Quest for the Heavens”) and Mengtian (“Dreaming of the Heavens”), which will be permanently attached to either side of the core. As the station’s management and control center, Tianhe can accommodate three astronauts for stays of up to six months. Visiting astronauts and cargo spaceships will connect to the central module at opposite ends. Both he and Wentian are equipped with robotic arms outside, and Mengtian has an airlock for maintenance and repair of experiments mounted outside the station. Tianhe has a total of five docking ports, which means that an additional module can be added for future expansion. The station is designed to operate for more than 10 years.
The CSS has less than a quarter of the mass of the ISS – the largest and most expensive man-made structure in space, which was built in cooperation by 15 countries. “We did not intend to compete with the ISS in terms of scale,” said Gu Yidong, chief scientist of the China’s manned space program. Instead, the three-module configuration is “based on China’s need for science experiments” and “what we consider a reasonable size for the sake of cost efficiency.”
To develop the CSS, China followed a three-step strategy by first building a crewed spacecraft (the Shenzhou missions), followed by mini space stations (Tiangong-1 and 2) and then the multimodule station which will be launched soon. Construction of the CSS was officially approved in 2010. Although the Chinese heavy rocket suffered a launch failure in 2017, delaying takeoff from Tianhe by more than a year, the country’s space leaders hopes to stick to the goal of completing construction of the space station by 2022 with intensive launches over the next two years.
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National and international experiences
The CSS will house 14 refrigerator-sized science experiment racks and a few general-purpose racks that will provide power, data, cooling and other services to various research projects. There will also be over 50 mooring points for experiments that will be set up outside the station to study how materials react to space exposure. the science inside and out will include space physiology, life sciences, fluid physics, materials science, astronomy and Earth observation. So far, around 100 experiments have been selected from more than 800 national proposals, Gu said. Some of them could start collecting data as early as next year.
For example, the station will use the world’s most accurate clocks and the coldest atoms to support basic research in general relativity and quantum physics. CSS clocks are designed to achieve incredibly low levels of instability, with only one second of error every three billion years. The ultra-cold atomic experimental medium can cool atoms to 10–10 Kelvin, the lowest temperature possible with current technologies. Some racks will be the first of their kind on a space station, including one dedicated to the study of phase changes between liquid and gaseous states of matter as these processes become much more distinct in microgravity. These studies could, for example, help develop smaller, more efficient cooling devices for spacecraft and even laptops.
The station will also reserve space and resources for a number of international experiences. Tricia Larose, medical researcher at the University of Oslo, directs Tumors in space, a 31-day experiment that will fly over CSS and test whether weightlessness can slow or stop cancer growth, among other goals. As one of the nine international projects Selected by the China Manned Space Agency (CMSA) and the United Nations Office for Outer Space Affairs (UNOOSA), the mission will use three-dimensional stem cell organoids, or “mini colon”, from cancerous and healthy tissue from the patient’s colon to study how DNA mutations are affected by microgravity. “All previous cancer experiments in space have used two-dimensional cell lines,” explains Larose. “By comparison, organoids mimic the structure and function of the organ and are the most physiologically relevant biological samples to use.”
Call for collaboration
The CSS can expect a business a year or two after its completion: China plans to launch a Hubble-sized telescope that will operate in the same orbit a few hundred kilometers away. As part of the CSS, the China Sky Survey Telescope (also called Xuntian) will have 300 times the field of view of Hubble and will address a wide range of sciences in the near UV and optical wavebands. The observatory will study cosmology, the large-scale structure of matter in the universe, galaxy, and star science, as well as dark matter and dark energy. It is designed to connect to the space station for service as needed, providing a simple, fuel efficient and “better way to engage astronauts to ensure telescope performance,” Gu explains.
Xuntian has similar designs and objectives to the European Space Agency’s Euclid mission and NASA’s Nancy Grace Roman Space Telescope, both of which will launch in the coming years, but they will work in bands of waves. complementary. Gu believes that the cooperation between the three telescopes and the sharing of observational data will lead to a deeper understanding of the universe and fundamental physics.
China welcomes the collaboration of scientists from all over the world on CSS, Gu said. Soon, the CMSA-UNOOSA collaboration will launch a second call for proposals for international experiences. Scientists can also apply through institutional partnerships to access space station resources. However, the level of international collaboration the CSS will receive is unclear due to geopolitical obstacles. US law heavily prevents NASA scientists from collaborating directly with China. In Europe, pressure from the agency is also making it difficult to obtain funding for projects that would involve the Chinese space program. Larose notes that she and her colleagues have encountered “an unexpected level of reluctance” with regard to CSS-related grant applications. It’s frustrating, she says, because cancer knows no borders and the search for a better cancer treatment benefits everyone in every country on the planet. “When are we going to stop looking at our differences and start focusing on our similarities?” Larose asks.
Ling Xin writes on physics, astronomy, spaceflight and related fields. More of his work can be found at lingxinwrites.com. Originally from Beijing, she is now based in Ohio. This story was provided by Scientific American.