Earth 2.0: China is hatching a plan to find Earth 2.0

China is hatching a plan to find Earth 2.0

China is planning its first space mission to survey the skies for exoplanets similar to Kepler-186f, an Earth-size planet orbiting a distant star (artist’s impression). Credit: NASA Ames/JPL-Caltech/T. Pyle

After sending robots to the Moon, landing them on Mars and building its own space station, China is now eyeing distant solar systems. This month, scientists will release detailed plans for the country’s first mission to discover exoplanets.

The mission will aim to survey planets outside the Solar System in other parts of the Milky Way, with the goal of finding the first Earth-like planet orbiting in the habitable zone of a star just like the Sun. Astronomers think such a planet, called an 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, mostly 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 none fit the definition of an Earth 2.0.

With current technology and telescopes, it is extremely hard to find the signal of small, Earth-like planets when their host stars are one million times heavier and one billion times brighter, says Jessie Christiansen, an astrophysicist at the NASA Exoplanet Science Institute at 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 wrapping up its early design phase. If the designs pass a review by a panel of experts in June, the mission team 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.

Seven eyes

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 survey the Cygnus–Lyra constellations, the same patch of sky that the Kepler telescope scoured. “The Kepler field is a low-hanging fruit, because we have very good data from there,” says Jian Ge, the astronomer leading the Earth 2.0 mission at the Shanghai Astronomical Observatory of the Chinese Academy of Sciences.

The telescopes 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 multiple small telescopes together gives scientists a wider field of view than a single, large telescope such as 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 satellite’s seventh instrument will be a gravitational microlensing telescope for surveying rogue planets — free-roaming celestial objects that don’t orbit any star — and exoplanets that are far from their star similar to Neptune. It will detect changes in starlight when the gravity of a planet or star warps the light of a background star that it is passing in front of. The telescope will target the centre of the Milky Way where massive numbers of stars are located. If successfully launched, this would be the first gravitational microlensing telescope that operates from space, says Ge.

“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

NASA launched Kepler in 2009, aiming to find out how common Earth-like planets are in the Galaxy. To confirm that an exoplanet is Earth-like, astronomers need to measure the time it takes to orbit its sun. Such planets should have an orbital period similar to Earth’s and transit their suns about 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.

But four years into the Kepler mission, parts of the instrument failed, rendering the telescope unable to stare at one patch of the sky over an extended period of time. Kepler was on the cusp of finding some truly Earth-like planets, says Huang, who has worked with the Earth 2.0 team as a data-simulation consultant.

With Earth 2.0, astronomers could have another four years of data that, when combined with Kepler’s observations, could help to confirm which exoplanets are truly 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 hopes to find a dozen Earth 2.0 planets. He says he plans to publish the data within one or two years of their 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, mostly from China, but Ge hopes more astronomers worldwide 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.

China is on the hunt for ‘Earth 2.0’ with proposed space telescope

An artist’s depiction of a collection of exoplanets.
(Image credit: NASA/JPL-Caltech)

China could soon begin its first space-based hunt for exoplanets, if a proposal from the Shanghai Astronomical Observatory (SAO) gets the go-ahead this summer.

The Earth 2.0 Telescope would spend four years orbiting sun-Earth Lagrange point 2, about 930,000 miles (1.5 million kilometers) from Earth. There, it would fixed its seven telescopes on a portion of the sky toward the galactic center and watch for signs of dimming as planets transit, or pass in front of, a star as they orbit.  

The main targets are roughly Earth-size exoplanets with similar orbits around sun-like stars. This requires high sensitivity to spot the signals of small-planet transits, as well as long-term monitoring to glimpse planets that take an Earthly year to go around their star.

Related: NASA needs a new telescope, ASAP, to find Earth’s twin

The Earth 2.0 Telescope would not be able to confirm an Earth twin on its own; rather, it would measure planets’ sizes and orbital periods to identify candidates for follow-up observations for potential habitability, Ge Jian, a professor at the SAO, told Space.com via email.

«These planet candidates can be followed up with ground-based telescopes to obtain radial velocity measurements to determine their masses and densities,» Ge said. «Some of these planet candidates around bright stars can be further followed up with ground-based or space-based spectroscopy to obtain transmission spectra of planets to study their atmospheres’ compositions. «

The mission would follow up on observations of an area of space that NASA’s Kepler space telescope studied for nine years, but the Earth 2.0 Telescope would have a much greater field of view, meaning it would be able to observe a larger area and more stars, Ge said. 

Kepler’s field of view was 115 square degrees; it observed half a million stars and discovered 2,392 exoplanets, with a similar number of candidate planets awaiting confirmation. Although the telescope detected some terrestrial planets, none around sunlike stars were potential Earth twins.

The Earth 2.0 Telescope, in comparison, would cover 500 square degrees and monitor 1.2 million dwarf stars for four years with six of its seven 11.8-inch-aperture (30 centimeters) telescopes. For reference, the apparent area of ​​the moon in the sky is about 0.5 square degrees, while the whole sky is about 41,000 square degrees. The telescope would also be able to view dimmer and more distant stars, adding to its survey capabilities.  

«As the transit method is a statistical game, the more suitable solar-type stars you search, the higher chance you would detect an Earth 2.0,» Ge said. «If the Earth 2.0’s occurrence rate is 10%, then we need to search roughly 2,000 relatively bright, quiet solar-type stars to detect an Earth 2.0’s transit.

«Our survey simulations show that we expect to detect about 30,000 new planets, including around 5,000 terrestrial-like planets, by our ET [Earth 2.0 Telescope] mission,» Ge said, adding that the six-telescope design and better signal-to-noise ratio detectors would also boost its capabilities.

The seventh telescope, meanwhile, would have the sensitivity to detect cold or free-floating rocky planets — also known as rogue planets — as small as Mars, by looking for the effects of a planet’s gravity bending starlight as it passes by. It would also be able to spot cold planets orbiting stars at distances comparable to those at which Mars and Neptune orbit the sun.

«The ability of the Earth 2.0 telescope to continue the survey started by Kepler, and extend this to planets on longer and cooler orbits, is incredibly exciting,» said Elizabeth Tasker, an associate professor at the Japan Aerospace Exploration Agency. «Our current exoplanet discoveries have not yet been able to probe these regions thoroughly, leaving us unable to properly mine the data to seek trends and patterns that would tell us how planets form, including rocky worlds in similar orbits to the Earth.»

Tasker and her students have been using machine learning to try to identify patterns. Better data would help reveal trends that could provide valuable insight into planetary formation.

«This mission will provide a lot of data for the international planet-hunting communities to study, and also planet candidates for them to conduct follow-up studies to measure their properties such as masses, densities and atmospheric compositions,» Ge said.  

The Earth 2.0 telescope will be able to find Earth-size worlds on similar orbits to our planet’s. «This is the first step in finding a planet that might be habitable,» Tasker said. 

But a planet’s radius and orbit alone do not tell us about its surface conditions. «Such a planet might well host a Venus or Mars environment on its surface, or perhaps something even more alien still,» Tasker said. «To discover if a planet is Earth-like and might be habitable or even inhabited, we will have to wait until we can probe the atmosphere or maybe even properties of the surface.»

The Earth 2.0 proposal is part of a Chinese Academy of Sciences space-science satellite program. Other mission proposals are competing for funding in areas such as astronomy and space science, solar and space physics, planetary science, and Earth observation.

Related stories:

Decisions on funding are expected in June. If the Earth 2.0 Telescope mission is selected, the team will begin readying the satellite for a 2026 launch. Another exoplanet proposal, which seeks to find exoplanets by measuring how a star wobbles around the center of mass of the system due to the influence of planets’ gravity, is also in the running.

China only recently began developing its own space-science missions, while other areas of space activities — such as human spaceflight, lunar exploration, and remote sensing and communications — have been thriving for years. China’s first round of space-science missions included the Wukong dark matter probe, the Hard X-ray Modulation Telescope and the Mozi quantum science satellite, all of which launched between 2015 and 2017. 

Follow us on Twitter @Spacedotcom and on Facebook.

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: [email protected].

Andrew is a freelance space journalist with a focus on reporting on China’s rapidly growing space sector. He began writing for Space.com in 2019 and writes for SpaceNews, IEEE Spectrum, National Geographic, Sky & Telescope, New Scientist and others.  Andrew first caught the space bug when, as a youngster, he saw Voyager images of other worlds in our solar system for the first time. Away from space, Andrew enjoys trail running in the forests of Finland. You can follow him on Twitter @AJ_FI .

Moving to the planet «Earth 2.0»?

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Kepler Space Telescope
Photo source: NASA

July 23, 2015 announced that using the telescope
Kepler found the first Earth-like exoplanet, Kepler-452 b.
Have people made other attempts to find «Earth
2.0»?

The report of the World
Wildlife Fund (WWF) on the human ecological footprint
it is said that man uses more resources than the planet
able to recover. To meet the needs of earthlings already
need 1.6 of our planet. And if every person on Earth led
such a way of life as the average Russian, then we
it would take 3. 3 planets already. Undoubtedly, steps must be taken to
way to the most sustainable resource consumption for the Earth, but
some scientists are already looking for a «plan B». Are there planets that
a person could potentially relocate?
nine0006

A space telescope set out to search for Earth-like planets
Kepler, it was launched by NASA in March 2009. «Kepler» became
the first spacecraft designed specifically for this purpose.
The search process was as follows: the telescope tries to capture in
his view of the maximum number of stars, at the same time he
over 100,000 watch. If any star within
is lost from view for a short time, probably obscuring it
planet. In order not to miss this phenomenon, the brightness of the stars
measured at least once every few hours. So
«transit of exoplanets» was detected.
nine0006

The results were not long in coming. Just a few months later
Kepler has found 5 potential exoplanets. June 2014
the activity of the spacecraft has been expanded. New mission
called «K2», in which she continued to search beyond
initial observations.

In order to identify the most Earth-like planets,
scientists have developed
Earth Similarity Index (ESI).
It helps answer the question of whether there are conditions on other
celestial bodies similar to earthly ones? Size, weight,
density, distance from the star and temperature on the planet. Most
a high value of the index — one — at the Earth, because
other planets are compared with it. In 2015, the Kepler telescope
found an exoplanet, which is currently considered the most
similar to the Earth — «Kepler-438 b», which is located from the Solar
systems at a distance of 473 light years. Earth similarity index
is 0.88, this mesoplanet is in the habitable zone,
therefore, the existence of rivers, lakes,
oceans.
nine0006

The Kepler mission ended on November 15, 2018. The telescope is not
enough fuel to return to orbit, and it was disconnected from
works on the day of Johannes Kepler’s death. According to sciencenews.org,
by the end of the mission, more than 3800 were known
exoplanets, the Kepler space telescope discovered 2720 of
them.

Artist’s rendering of the exoplanet Kepler-1649c orbiting its red dwarf star.

Photo source: NASA

Sources:

Ecological footprint of the constituent entities of the Russian Federation.
WWF Russia

Kepler (telescope).
Wikipedia

Earth similarity index.
Wikipedia

Kepler and K2. mission overview.
NASA

exoplanets.
NASA

The planet-hunting Kepler space telescope is dead.
sciencenews

Author Anastasia Ibragimova

NASA
earth similarity index
exoplanets
ecological footprint
search for an analogue of the Earth
terrestrial planet
Kepler

space telescope

Information provided by the Information Agency «Scientific Russia». Mass media registration certificate: IA No. ФС77-62580, issued
Federal Service for Supervision of Communications, Information Technology and Mass Communications on July 31, 2015.

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China joins the race to find the most habitable Earth-like exoplanets

China’s new satellite will be «10 to 15 times more powerful than NASA’s Kepler telescope. » It will explore the Milky Way in search of exoplanets orbiting stars like the Sun

China is making every effort to become one of the leading space powers in the world. The country has only recently launched its first rovers to the Moon and Mars and built its own space station.

The country’s space agency is now set to join the competition to find habitable exoplanets, according to the journal Nature. This month, scientists will present a detailed plan for the first mission to search for and study extrasolar objects potentially suitable for life. nine0006

The Chinese space agency intends to join the race to find habitable exoplanets. oorka/iStock

In Search of Earth 2.0

The purpose of the mission is to search for planets (a term for any planet outside our solar system) similar to Earth within the Milky Way, which orbit in the habitable zone of their Sun. Scientists believe that such a planet may have ideal conditions for the emergence of life.

NASA recently announced that over 5,000 exoplanets have now been discovered, largely thanks to the Kepler telescope. However, none of them technically fit the definition of Earth 2.0 because they are not in the habitable zone.

The Chinese Space Agency hopes to be the first to make this discovery. The new project will be funded by the Chinese Academy of Sciences. It is currently at an early stage of development, and its examination is scheduled for June this year. If everything goes according to schedule, the satellite will go into space on a Long March rocket as early as 2026. nine0006

China’s Earth 2.0 satellite will carry seven telescopes, six of which will observe the constellations Cygnus and Lyra. The satellite will scan more than 1.2 million stars in a 500-square-degree region of the sky, nearly five times the capacity of Kepler. It will also be able to observe dimmer, more distant stars than NASA’s current Transiting Exoplanet Survey Satellite (TESS), which monitors the stars closest to Earth.

«Our satellite could be 10 to 15 times more powerful than NASA’s Kepler telescope in terms of its observational capabilities,» said Jian Ge, head of the Earth 2.0 astronomical mission at the Shanghai Astronomical Observatory of the Chinese Academy of Sciences. nine0006

A lot of data will be collected

Earth 2.0’s six main telescopes will search for exoplanets, detecting fluctuations in star brightness that indicate the presence of large objects within orbit. The seventh instrument of the Earth 2.0 project, the gravitational microlens telescope, is designed to search for rogue planets, as well as exoplanets that are at a great distance from their Sun.

«Our satellite can actually do a ‘census’ and identify exoplanets of various sizes, masses and ages. The mission will help prepare a good database for future research,» Ge says. nine0006

In order to find Earth 2.0, scientists will need to make sure that it has an Earth-like orbit and a period of revolution around its star that is roughly equal to an Earth year.