China has announced its first plans to search the stars for nearby habitable planets that could one day expand humanity’s “living space” across the Milky Way.
In the project, called Closeby Habitable Exoplanet Survey (CHES), officials propose to launch a space telescope with an aperture of 3.9 feet (1.2 meters) about 930,000 miles (1.5 million kilometers) to ‘at a gravitationally stable Lagrange point between Earth and the Sun, according to the Chinese news service CGTN. The Lagrange points revolve around the sun at exactly the same rate as the Earth, which means that a craft at one of these points will remain at the same distance from our planet indefinitely.
Once at the Lagrange L2 point (which also houses the James Webb Space Telescope) the CHES telescope will spend five years searching for habitable worlds through the roughly 100 sun-like stars within 33 light-years (10 parsecs) of Earth. From this data, astronomers hope to pinpoint the size of the Earth exoplanets which move around their stars in orbits similar to our own – a hint that these potential “Earth 2.0s” may harbor water, and possibly even life.
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“The discovery of nearby habitable worlds 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,” said Ji Jianghui, an astronomer at the Chinese Academy of Sciences and Senior Researcher. of the CHES mission, told CGTN, the website of China’s Global Television Network. Scientists say they hope to find around 50 Earth-like exoplanets or super-Earths in their search.
According NASA exoplanet catalog, 3,854 of the 5,030 known exoplanets were discovered by a technique known as the transit method, which was first used in 1999 to discover the planet HD 209458b. The transit method works by directing a telescope’s views toward the galactic center and watching for the telltale flicker of starlight as planets pass in front of their host star. So far, it has been used by NASA’s Kepler Space Telescope, its Transiting Exoplanet Survey Satellite (TESS), and the European Space Agency’s (ESA) Characterizing Exoplanet Satellite (Cheops) to spot and study exoplanets.
But the transit method can be slow, requiring a planet orbiting its star several times before scientists can confirm a detection. Additionally, the method can only detect an exoplanet’s radius (not its mass or orbit shape), and it requires assisting readings from ground-based telescopes to confirm that dimming signals are not not caused by other stellar activity, say the researchers. .
The newly proposed telescope could spot exoplanets faster and in greater detail using a different method called astrometry; with this method, scientists would look for telltale oscillations of stars caused by the gravitational tugs of orbiting planets. If a star is very wobbly compared to the six to eight reference stars behind it, the CHES telescope will flag it for further investigation. Then, by studying the specific way a star wobbles, the researchers say they will be able to identify the mass of exoplanets orbiting it and map their three-dimensional trajectories around it.
However, astrometry has been the cause of multiple controversies among exoplanet hunters. Spotting planets from the tiny wobbles of stars requires extremely precise measurements, and so far only one confirmed exoplanet has relied on the technique, according to the Planetary Society. One of the most famous false positives produced by the method is the 1963 claim by Swarthmore College astronomer Peter van de Kamp, who announced the discovery of a planet orbiting Barnard’s Star; but further checks revealed that his measurements came from a false reading produced by adjustments to the telescope’s main mirror, not by pulling planets. Van de Kamp’s exoplanet simply did not exist.
So far, only preliminary investigations into the viability of the proposal have been carried out by teams from various Chinese research institutions, so the project is not certain to go ahead. But we may not have to wait too long for a test of astrometry’s ability to spot distant worlds. ESA’s GAIA spacecraft, which until now has accurately mapped the location of stars, is also expected to use astrometry to find distant exoplanets. Some of these astrometric readings could feature in ESA’s next release of data returned from the GAIA spacecraft, which is expected to arrive later this year.
Decisions on funding for the CHES mission are expected in June, and if selected, the team will work to build the new telescope for a 2026 launch. The proposal rivals another exoplanet project called Earth 2.0 in which an array of seven transit method satellites would be launched at Lagrange point L2.
China is turning its gaze to other planets during a period of growing ambition for its scientific study of space. China has landed rovers on the Moon and Mars, and it also plans to complete its first space station by the end of this year and have a functioning lunar base by 2029. The space agency the country has also launched a dark matter probe, an X-ray telescope to study neutron stars and black holes, and a quantum communications satellite. China is also expected to break its own world record for space launches this year, having planned 60 launches in 2022, five more than in 2021, Live Science previously reported.
Originally posted on Live Science.