China goes in search of new lands

It is one of the most complicated space missions ever considered in China. The Miyin project will have four space telescopes, which will fly in formation with a fifth vehicle. Everything will be placed at the Lagrange point L2 of the Earth-Sun system. Several demonstration stages are on the program before a commissioning objective in the early 2030s.

Chinese James-Webb telescope fault

The resolution of the James-Webb Telescope (JWST) is currently unmatched, its focal length unprecedented, and its sensitivity to light impressive. China is currently unable to produce an equivalent space telescope. CNSA (China National Space Agency- Chinese space agency) is building an equivalent of the Hubble Space Telescope. With the Miyin mission, the CNSA seeks to directly image exo-Earths.

If you want to search for extraterrestrial life, exo-Earths are by far the best candidates outside our solar system. The CNSA wants to find, image, and study their habitability. For this, Miyin will look for them around stars similar to our Sun, and will study their signal in infrared. This is the reason why telescopes must be sent into space: this radiation is censored by the filtering of our atmosphere.

Miyin’s research field will be restricted to stars in our vicinity, within a distance limit of 65 light years. But to directly image exo-Earths around their star will require a lot of total area to directly acquire every photon from the targets. The surface of the four space telescopes is not yet known at this stage of the project’s development.

NASA’s HabEx project. © NASA, JPL-Caltech

Exo-synchronization

To guarantee excellent angular resolution, the Miyin project will rely on interferometry techniques. This is the role of the fifth element of the fleet: to combine the collected beams. The telescopes and the combiner will be 40 to 300 meters apart. They will thus be able to provide a spatial resolution of 0.01 second of arc for systems at 20 parsecs.

Indeed, good resolution is needed to be able to distinguish the weak light signal from the planet, reflecting that of its star, without confusing them both in the same set of pixels. The analysis of the spectrum of the exoplanet will be very difficult otherwise. Miyin’s resolution would be equivalent to that of the future project The Habitable Worlds Observatory (HabEx) from NASA, a set of space telescopes whose mirror diameter should reach six meters and which will include a coronagraph.

Several demonstrations before commissioning

Project details have been revealed during an event on the sidelines of the China Space Day 2023, celebrating the anniversary of the launch of the very first Chinese satellite on April 24, 1970. China is increasingly interested in exoplanets. Several other missions are also under study. Miyin will also study protoplanetary disks, from which future star systems form.

Miyin is in the design phase, under the aegis of the China Aerospace Science and Technology Corporation (CCAC). Several demonstrations are planned before construction: a technology test mission in orbit in 2024, as well as several interferometry experiments in space from the Chinese space station the following year. Commissioning is scheduled for 2030, with a possible addition of four additional space telescopes to the fleet a few years later.