Why some scientists choose China’s space station for research

Seeking to boost its prestige in the world, China is promoting its Tiangong orbital outpost as a space station available to scientists around the world, not just those living in other countries with established space programs.

“We are ready to carry out more international cooperation and exchanges with countries and regions engaged in the peaceful use of outer space,” Chinese Foreign Ministry spokesperson Wang Wenbin said in April. .

For the International Space Station – a partnership between NASA, Russia, Canada, the European Space Agency and Japan that has been in orbit for more than two decades – the laboratory’s resources are distributed among the partner countries, which then offer their scientists the ability to send experiments to the space station.

But scientists living in countries that are not part of the partnership are generally excluded from the ISS

Through a United Nations program called Access to Space for All, China has offered scientists from any country the opportunity to have their experiments transported to the Tiangong space station.

The United Nations announced the first set of nine awards in 2019, which included projects from India, Japan, Peru, Mexico and Saudi Arabia.

One of the selected experiments, POLAR-2, is an international effort led by the University of Geneva to study gamma-ray bursts from a distance.

Gamma-ray bursts are among the most violent explosions in the universe, caused by exploding stars or merging neutron stars. The explosions send short, intense bursts of ultra-high energy photons called gamma rays traveling through the universe.

As its name suggests, POLAR-2 is the follow-up to POLAR, a smaller detector that flew to an older, smaller Chinese space laboratory prototype.

“Historically, the University of Geneva had a close connection with Chinese research groups,” said Merlin Kole, project manager of POLAR-2, which is scheduled to launch in Tiangong in 2025.

The experiment examines whether the gamma rays from a gamma-ray burst align in a particular way. More than a decade ago, measurements made by an instrument on a Japanese spacecraft suggested that gamma rays were often linearly polarized – that is, the oscillating electric fields of gamma rays were parallel to each other. others like a squadron of planes flying flat rather than with their wings angled in all directions.

But data from POLAR, which flew in 2016, suggested that gamma rays were not polarized.

POLAR scientists have thought about how to launch a larger tracking detector into space. They decided not to seek to build their own dedicated satellite.

“It would be much more complex overall,” said Agnieszka Pollo, an astrophysicist at the National Center for Nuclear Research in Poland and principal investigator for the Polish part of the POLAR-2 collaboration.

And the International Space Station wasn’t seen as viable either because “there’s a lot of competition for it,” Dr Pollo said, “and it’s not that cheap and that easy either.”

So when the research opportunity for Tiangong was announced, “relatively quickly, we were able to submit something and we were accepted in the first round,” Dr. Kole said.

Tiangong’s high-speed communications system will send tens of gigabytes of data to the ground every day. This will allow scientists to analyze any data that may contain nuggets of discovery such as very weak gamma-ray bursts or other astrophysical events that might otherwise be dismissed as noise.

There is also a supercomputer on the space station to analyze data while it is still in space. This will make it possible to quickly calculate the origin of a gamma-ray burst. This information could then be shared with astronomers in the field for quick follow-up observations using other telescopes, Dr Kole said.

So far, working with Chinese space officials has gone well, Dr. Kole said, although it may involve wading through Chinese bureaucracy.

“There are multiple agencies involved, and we don’t speak to them directly,” he said. “So that makes it a little tricky sometimes. But when we really need to know something, we find out.

Since the $2 million instrument is largely built in Europe and then shipped to China, the project also involves bureaucracy and paperwork with European officials.

“We don’t give away secrets, of course,” Dr. Kole said. “All the components are relatively simple and nothing is secret. It is a scientific instrument. But, yes, there is no very clear bureaucratic channel to do it correctly.