Particle physics experiments

Chinese space station to host 1,000 science experiments


Chinese astronaut Nie Haisheng works inside the Tianhe module.Credit: Jin Liwang / Xinhua / eyevine

China launched the core of its space station in April and sent three astronauts in June. But while the space station is unlikely to be finished until late 2022, there is already a long line of experiments from around the world waiting to go up. Chinese scientists said Nature that the Chinese Manned Space Agency (CMSA) has provisionally approved more than 1,000 experiments, several of which have already been launched.

Prior to April, the International Space Station (ISS) was the only space laboratory in orbit, and many researchers say Tiangong (or “heavenly palace”) is a welcome addition for astronomical and terrestrial observation, and for studying how microgravity and cosmic radiation affect the phenomena. such as bacterial growth and mixing of fluids.

However, others argue that manned space stations are expensive and serve a political rather than a scientific purpose.

“Increased scientific access to space has a scientific advantage on a global scale, regardless of who builds and operates platforms,” ​​says Julie Robinson, chief scientist for human exploration and operations at headquarters. NASA in Washington DC.

“We need more space stations, because one space station is certainly not enough,” adds Agnieszka Pollo, an astrophysicist at the National Nuclear Research Center in Warsaw who is part of a team that sends an experiment to study them. starts.

Open to the world

The ISS was launched in 1998, as part of a partnership between space agencies in the United States, Russia, Europe, Japan and Canada (see “Variations on a Theme”). It has hosted more than 3,000 experiments since then, but China is banned from doing so due to US rules that prohibit NASA from using funds to collaborate with China.

Although most of the experiments planned for Tiangong will involve Chinese researchers, China says its space station will be open to collaboration from all countries, including the United States.

In June 2019, CMSA and the United Nations Office for Outer Space Affairs (UNOOSA), which promotes collaboration in space, selected nine experiments – in addition to the 1,000 that China tentatively approved – to mount once the completed space station. Simonetta Di Pippo, director of UNOOSA in Vienna, said it was 23 institutions in 17 countries.

Variations on a theme: Diagram comparing the Tiangon space station to the International Space Station.

China previously launched two small space labs – Tiangong-1 and Tiangong-2. These have hosted more than 100 experiments, circling the Earth for several years, but are no longer in orbit.

The space station offers completely new facilities and China is encouraging experiments that had not yet been attempted in space, says Tricia Larose, a medical researcher at the University of Oslo, who is leading a project scheduled for 2026. ” They say, yes, build your material, make it brand new, do something that has never been done before and send it to us.

Even though most of the projects approved so far are led by Chinese researchers, many have international collaborators, says Zhang Shuang-Nan, an astrophysicist at the Institute of High Energy Physics at the Chinese Academy of Sciences (CAS). in Beijing, which advises the CMSA.

“Scientists’ playrooms”

The first section of Tiangong to arrive was a basic module known as Tianhe (“harmony of the heavens”). At the end of May, a freighter named Tianzhou-2 (“celestial ship”) was dispatched and docked, delivering fuel, spacesuits and experimental equipment. In June, three Chinese astronauts – or “taikonauts” – aboard the Shenzhou-12 (“divine vessel”) also docked, entering the 17-meter-long chamber that will be their home for the next three months.

Over the next year or more, CMSA will send eight more missions to Tiangong. Two will deliver the Wentian (“quest for paradise”) and Mengtian (“dream of paradise”) modules, which will mainly house science experiments (see “China’s first space station”).

China's first space station: artist's concept of Tiangon in orbit detailing how the modules will be used.

Image Credit: Adrian Mann / Stocktrek Images / Alamy

These will be “scientists’ playrooms,” explains Paulo de Souza, a physicist at Griffith University in Brisbane, Australia, who is developing sensors for use in space.

The space station will have more than 20 experimental racks, which are mini-laboratories with closed and pressurized environments, said Yang Yang, director of international cooperation at the CAS Technology and Engineering Center for the use of the space in Beijing. Outside, there will be 67 connection points for research material facing the Earth or the sky, Yang explains. A powerful central computer will process the data from the experiments before sending them back to Earth.

Organoids and dark matter

The experiments sent to the new space station span many fields. Zhang is the principal investigator of HERD (High Energy Cosmic-Radiation Detection Facility), a partnership between Italy, Switzerland, Spain and Germany, scheduled for 2027. This particle detector will study dark matter and rays cosmic, and will cost around 1 billion to 2 billion yuan ($ 155 to 310 million), according to Zhang.

Zhang and Pollo are also involved in POLAR-2, which will study the polarization of rays emitted by large and distant explosions, with the aim of clarifying the properties of ray bursts, and possibly even gravitational waves.

Larose plans to send 3D drops of healthy and cancerous intestinal tissue called organoids. She wants to know if the ultra-low gravity environment will slow or stop the growth of cancer cells, which could lead to new therapies.

Chinese astronaut Liu Boming wearing a space suit exits a space station central module during extravehicular activity

‘Taikonaut’ Liu Boming performs China’s second spacewalk after arriving in Tiangong in June.Credit: Jin Liwang / Xinhua / eyevine

Other projects by Indian and Mexican scientists will study ultraviolet emissions from nebulae and infrared data from Earth, in order to study weather conditions and the causes of intense storms.

Although many projects are partnerships between Chinese and Western scientists, geopolitical tensions have made collaborations more difficult, notes Larose. She said Norway has yet to sign a bilateral agreement with China that would give the project the green light. Merlin Kole, an astrophysicist at the University of Geneva in Switzerland, who also works on POLAR-2, adds that stricter compliance with export regulations means there is additional bureaucracy around sending electronic equipment in China.

But Di Pippo says the tensions have so far had no impact on the progress of projects selected by UNOOSA, adding that the agency is discussing plans with CMSA to send more experiments to Tiangong from here the end of next year.

Scientific value for money

Some scientists have argued that manned space stations are a waste of money – the cost of Tiangong has not been made public, but the ISS has cost around 100 billion euros ($ 118 billion) to build and maintain during its first decade.

“Robotic missions would get you a lot more bang for your buck,” said Gregory Kulacki, China security analyst for the Union of Concerned Scientists, an advocacy group based in Cambridge, Massachusetts. “In China, as in the United States, there has been tension between scientists who want to do the best science possible and who prefer robotic missions, and governments who want to use manned space flight programs largely for human beings. political purposes. “

But other researchers point out that while satellites offer an alternative for some observations, for many experiments, especially those requiring microgravity, manned space stations are essential. They provide a place for long-term observation, data processing capability, and access to astronauts who can perform maintenance tasks and conduct the experiments.

In addition, in addition to the researchers’ housing experiments, Tiangong is intended to test human space travel technologies to support China’s space exploration goals, Zhang said.

With the current funding for the ISS only extending until a certain time between 2024 and 2028, there is also the possibility that Tiangong will eventually become the only operating space station on Earth.

Tiangong is expected to operate for at least a decade, and China is already planning to launch other spacecraft to work in tandem with it. The China Survey Space Telescope, or Xuntian (“watch the skies”), is a two-meter optical telescope that will rival NASA’s Hubble Space Telescope and periodically dock in Tiangong for refueling and maintenance. Scheduled to launch in 2023, it will have a wider field of view to scan the deep universe than Hubble.