China proposes mission to alien planet to hunt habitable worlds

A proposed Chinese mission would search for potentially habitable alien worlds nearby by launching a spacecraft to take ultra-precise measurements of how orbiting planets wobble a star.

For this mission, called the Closeby Habitable Exoplanet Survey (CHES), scientists would use a method called relative microarcsecond astrometry. This technique involves taking ultra-precise measurements of the positions and motions of stars relative to a set of background reference stars to detect disturbances to a star resulting from the gravitational influence of exoplanets orbiting their planets. stars.

This method would provide estimates of the masses of exoplanets and the distance at which they orbit their stars, which, in turn, could reveal whether these exoplanets have the potential to host life. The European Space Agency’s Gaia Space Telescope uses the same method to create a 3D map of a billion stars in the Milky Way. (Other planet-finding missions, such as NASA’s Transiting Exoplanet Survey Satellite, use a different technique, called the transit method, which looks for dips in a star’s brightness as planets pass through it. However, This method requires the planets to orbit around the edge relative to the observer.)

Related: The 10 most Earth-like exoplanets

CHES would be much more concentrated than Gaia, targeting 100 sun-like stars within 10 parsecs, or 33 light-years, of Earth and would be able to detect potentially Earth-like planets in the habitable zones around those stars.

While monitoring a relatively small selection of stars, CHES would be able to thoroughly study these systems for exoplanets.

“The hunt for habitable worlds around stars close to the sun will be a great breakthrough for mankind, and will also help humans to visit these Earth twins and expand our living space in the future,” Ji said. Jianghui, a research professor at the Purple Mountain Observatory. at the Chinese Academy of Sciences (CAS) and principal investigator of the CHES mission, told “To date, more than 5,000 exoplanets have been discovered and confirmed to date, including about 50 Earth-like planets in the habitable zone, but most of them are hundreds of light years from Earth.”

CHES would carry out its work from Sun-Earth Lagrange Point 2, about 930,000 miles (1.5 million kilometers) from Earth, where Gaia, Spektr-RG and the James Webb Space Telescope currently operate.

“CHES would be a fabulous addition to exoplanet exploration,” said Elizabeth Tasker, associate professor at the Japan Aerospace Exploration Agency. “Although the potential number of targets is small, measuring the planetary mass of worlds orbiting our neighboring K-, G-, and F-type stars would be a valuable addition to our current data and a step towards identifying worlds. habitable.”

Measuring planetary masses would provide valuable data on the diversity and formation of our planetary neighbors, Tasker said.

“Although CHES cannot probe the surface of these planets to see if they host an Earth-like environment, direct mass measurement provides an important indicator as to which planets definitely might or might not resemble Earth.” , Tasker told Space. .com. “Higher-mass planets will attract a thicker atmosphere than Earth, potentially containing gases such as hydrogen and helium, which are excellent at trapping heat.”

The potential habitability of terrestrial planets from the findings made by CHES could be further investigated by other teams. For a planet making observable transits through its star, spectra of light passing through an exoplanet’s atmosphere could be analyzed to reveal information about its composition.

The mission appears to be in competition with another exoplanet proposal from the Shanghai Astronomical Observatory, also under CAS. This so-called Earth 2.0 mission would use the transit method to monitor 1.2 million dwarf stars, with the aim of detecting exoplanets and narrowing down the search for potential Earth twins. This mission would also operate from Sun-Earth Lagrange Point 2.

Both proposals are part of a third round of the CAS Strategic Priority Research Program. These two proposals, as well as mission proposals in other fields – including extreme energy physics, planetary science, heliophysics and Earth observation – should be considered soon.

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