China hatches a plan to find Earth 2.0 news and research
After sending robots to the moon, landing them on Mars and building its own space station, China is now looking at distant solar systems. This month, scientists will release detailed plans for the country’s first mission to discover exoplanets.
The mission will aim to map planets outside the solar system in other parts of the Milky Way, with the goal of finding the first Earth-like planet orbiting the habitable zone of a star just like the sun. Astronomers believe that such a planet, called Earth 2.0, would have the right conditions for liquid water – and possibly life – to exist.
More than 5,000 exoplanets have already been discovered in the Milky Way, most with NASA’s Kepler telescope, which was in use for 9 years before it ran out of fuel in 2018. Some of the planets were rocky Earth-like bodies orbiting small red dwarf stars. , but no one fits the definition of an Earth 2.0.
With current technology and telescopes, it is extremely difficult to find the signal from small Earth-like planets when their host stars are one million times heavier and one billion times brighter, says Jessie Christiansen, astrophysicist at the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena.
The Chinese mission, called Earth 2.0, hopes to change that. It will be funded by the Chinese Academy of Sciences and is completing its early design phase. If the design passes a review by an expert panel in June, the task force will receive funding to start building the satellite. The team plans to launch the spacecraft on a Long March rocket before the end of 2026.
The Earth 2.0 satellite is designed to carry seven telescopes that will observe the sky for four years. Six of the telescopes will work together to map the Cygnus – Lyra constellations, the same celestial spot that the Kepler telescope searched through. “The Kepler field is a low-hanging fruit, because we have very good data from it,” said Jian Ge, the astronomer leading the Earth 2.0 mission at the Shanghai Astronomical Observatory of the Chinese Academy of Sciences.
The telescope will look for exoplanets by detecting small changes in a star’s brightness that indicate that a planet has passed in front of it. Using several small telescopes together gives researchers a wider field of view than a single large telescope like Kepler. Earth 2.0’s 6 telescopes together will stare at about 1.2 million stars over a 500-square-degree part of the sky, which is about 5 times wider than Kepler’s vision was. At the same time, Earth 2.0 will be able to observe darker and more distant stars than NASA’s Transiting Exoplanet Survey Satellite (TESS), which examines bright stars near Earth.
“Our satellite can be 10-15 times more powerful than NASA’s Kepler telescope in its celestial measurement capability,” says Ge.
The satellite’s seventh instrument will be a gravitational micro-lensing telescope to map unscrupulous planets – free-roaming celestial objects that do not orbit a star – and exoplanets that are far from their star-like Neptune. It will detect changes in starlight when a planet’s or star’s gravity distorts light from a background star as it passes in front of it. The telescope will be aimed at the center of the Milky Way, where a huge number of stars are located. If launched successfully, this would be the first gravity micro-lensing telescope to work from space, says Ge.
“Our satellite can mainly conduct a census that identifies exoplanets of different sizes, masses and ages. The mission will provide a good collection of exoplanet samples for future research,” he says.
Doubling of data
NASA launched Kepler in 2009, in order to find out how common Earth-like planets are in the galaxy. To confirm that an exoplanet is Earth-like, astronomers must measure the time it takes to orbit its sun. Such planets should have an orbital period similar to that of the Earth and pass their suns about once a year. Chelsea Huang, an astrophysicist at the University of Southern Queensland in Toowoomba, says researchers need at least three transits to calculate an exact orbital period, which takes about three years of data, and sometimes more, if there are data gaps.
But four years into the Kepler mission, parts of the instrument failed, making the telescope unable to stare at part of the sky for an extended period of time. Kepler was on its way to finding some truly Earth-like planets, says Huang, who has worked with the Earth 2.0 team as a computer simulation consultant.
With Earth 2.0, astronomers can have another four years of data that, combined with Kepler’s observations, can help confirm which exoplanets are truly Earth-like. “I am very excited about the possibility of returning to the Kepler field,” says Christiansen, who hopes to study Earth 2.0’s data if they are made available.
Give hope of finding a dozen Earth 2.0 planets. He says he plans to publish the data within a year or two of the collection. “There will be a lot of data, so we need all the hands we can get,” he says. The team already has about 300 scientists and engineers, most of them from China, but Ge hopes that more astronomers around the world will join. “Earth 2.0 is an opportunity for better international cooperation.”
The European Space Agency is also planning an exoplanet mission – called Planetary Transits and Oscillations of Stars (PLATO) – which is scheduled to be launched in 2026. PLATO’s design has 26 telescopes, which means that it will have a much larger field of view than Earth 2.0. But the satellite will shift its gaze every two years to observe different parts of the sky.
This article is reproduced with permission and was not published until April 12, 2022.