Hot: China is devising a strategy to find Earth 2.0. - Beyond The World
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Hot: China is devising a strategy to find Earth 2.0.

After sending robots to the Moon, landing them on Mars and building its own space station, China is now eyeing distant solar systems. Scientists will disclose comprehensive plans for the country’s first mission to find exoplanets later this month.

The mission’s aim is to survey the first Earth-like planet orbiting in the habitable zone of a star similar to the Sun outside of the Solar System in other parts of the Milky Way. Astronomers believe that such a planet, dubbed Earth 2.0, would have the ideal circumstances for liquid water to exist, as well as the possibility of life.

More than 5,000 exoplanets have been identified in the Milky Way, largely because to NASA’s Kepler telescope, which was operational for nine years before running out of fuel in 2018. Some of the planets orbited small red dwarf stars and were rocky Earth-like bodies, but none fulfilled the description of an Earth 2.0.

According to Jessie Christiansen, an astrophysicist at the NASA Exoplanet Science Institute at California Institute of Technology in Pasadena, finding the signal of small, Earth-like planets with current technology and telescopes is extremely difficult when their host stars are one million times heavier and one billion times brighter.

Earth 2.0 is a Chinese mission that aims to change that. It is currently in the early design phase and will be supported by the Chinese Academy of Sciences. The mission team will receive money to begin building the satellite if the designs pass a review by a panel of specialists in June. The team plans to launch the spacecraft on a Long March rocket before the end of 2026.

Seven eyes

The Earth 2.0 satellite is designed to carry seven telescopes that will observe the sky for four years. Six telescopes will collaborate to examine the Cygnus–Lyra constellations, the same area of sky surveyed by the Kepler telescope. “The Kepler area is a low-hanging fruit since we have extremely strong data from there,” says Jian Ge, the astronomer in charge of the Earth 2.0 project at the Chinese Academy of Sciences’ Shanghai Astronomical Observatory.

Exoplanets will be discovered using telescopes that detect slight fluctuations in a star’s brightness that signal a planet has passed in front of it. Multiple small telescopes combined provide a larger field of view than a single giant telescope like Kepler. Earth 2.0’s 6 telescopes will together stare at about 1.2 million stars across a 500-square-degree patch of sky, which is about 5 times wider than Kepler’s view was. At the same time, Earth 2.0 will be able to observe dimmer and more distant stars than does NASA’s Transiting Exoplanet Survey Satellite (TESS), which surveys bright stars near Earth.

“Our satellite can be 10–15 times more powerful than NASA’s Kepler telescope in its sky-surveying capacity,” says Ge.

The seventh instrument on the satellite will be a gravitational microlensing telescope for surveying rogue planets (free-roaming celestial objects that don’t orbit any star) and exoplanets (like Neptune) that are far from their star. When the gravity of a planet or star warps the light of a background star it is passing in front of, it will detect changes in starlight. The telescope will focus on the Milky Way’s center, which contains a large amount of stars. According to Ge, if launched successfully, this will be the first gravitational microlensing telescope to operate from space.

“Our satellite can essentially 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 the data

Kepler was launched by NASA in 2009 with the goal of determining how common Earth-like planets are in the Galaxy. Astronomers must measure the time it takes an exoplanet to orbit its solar in order to prove if it is Earth-like. The orbital period of such planets should be identical to Earth’s, and they should transit their suns once a year. Chelsea Huang, an astrophysicist at the University of Southern Queensland in Toowoomba, says that scientists need at least three transits to work out a precise orbital period, which takes about three years of data, and sometimes more, if there are data gaps.

Parts of the Kepler telescope failed four years into the project, preventing the telescope from staring at a single patch of sky for long periods of time. According to Huang, who has worked as a data-simulation consultant with the Earth 2.0 team, Kepler was on the verge of discovering some truly Earth-like planets.

Astronomers may have another four years of data with Earth 2.0, which, when combined with Kepler’s observations, may help confirm which exoplanets are actually Earth-like. “I am very excited about the prospect of returning to the Kepler field,” says Christiansen, who hopes to study Earth 2.0’s data if they are made available.

Ge is hoping to discover a dozen Earth 2.0 worlds. He intends to disseminate the data within a year or two of its collecting. “There will be a lot of data, so we need all the hands we can get,” he says. The team now contains roughly 300 scientists and engineers, the majority of whom are from China, but Ge hopes that additional astronomers from around the world will join. “Earth 2.0 is an opportunity for better international collaboration.”

The European Space Agency is also planning an exoplanet mission — called Planetary Transits and Oscillations of Stars (PLATO) — that is scheduled to launch in 2026. PLATO’s design has 26 telescopes, meaning 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 regions of the sky.

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Angir H B
Angir H B
9 months ago

Good effort to expand our environment in the next 2000 years .I hope earth 2 will not seek to make us guinea-pigs in their medical research !

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