Hunting for Habitable Worlds: China to Launch Earth 2.0 Mission

China aims to launch a space observatory 1.5 million kilometres from Earth by 2028 to search for habitable planets. With the help of unique equipment, scientists will conduct the first large-scale study of Earth-like and rogue planets. It will help unlock the secrets of their origin and provide new candidates and directions for the search for extraterrestrial life.

Earth 2.0: New mission to find Earth’s twin

The first discovery of exoplanets occurred in 1992. Since then, astronomers have found nearly 9,000 exoplanet candidates and confirmed more than 5,000 objects of various types. Despite the development of observational tools, searching for minor planets in giant stars remains difficult.

Space telescopes such as Kepler, COROT and TESS, which search for exoplanets using the transit method, or CHEOPS, which investigates already discovered objects, have played a considerable role in the search for exoplanets.

Now, China aims to launch an exoplanet observatory, hoping to discover a potential second Earth.

According to the research article published in the Chinese Journal of Space Science, ‘the Earth 2.0 (ET) mission will pioneer an international breakthrough in the cutting-edge science problem of the existence and evolution of Earth 2.0 (or exo-Earths) in the origin of life by utilising the key technology of ultra-precise, large-field-of-view photometry in space.’

The mission, funded by the Chinese Academy of Sciences, is expected to be launched into Earth orbit using a Changzheng series rocket by the end of 2028.

Continuing the Kepler Affair

To study exoplanets, the mission’s ideal orbit should be away from electromagnetic interference near Earth and operate in a relatively clean dynamic environment to reduce the magnitude and frequency of orbit maintenance.

The space observatory is deployed towards the galactic centre on a halo orbit at the Lagrangian point L2 of the Sun-Earth System (SEL2). This region of space is one of several where the gravitational fields of the Earth and Moon are in equilibrium, providing the spacecraft with stability and minimal fuel consumption for a long lifetime.

The spacecraft’s estimated lifespan is four years. During that time, the observatory will observe about 1.2 million stars in a patch of sky in the constellations of Swan and Lyra, sending about 169 GB of data back to Earth daily.

The area was previously the subject of research by the Kepler telescope, which launched in 2009. Kepler has observed half a million stars and discovered 2,392 exoplanets. Although the telescope detected several Earth-group planets until 2018, when it was switched off, none were potential Earth doppelgangers. By comparison, the Earth 2.0 telescope will observe 1.2 million dwarf stars.

Seven Eyes of the “Earth 2.0” Observatory

To study exoplanets, the mission’s ideal orbit should be away from electromagnetic interference near Earth and operate in a relatively clean dynamic environment to reduce the magnitude and frequency of orbit maintenance.

The space observatory is deployed towards the galactic centre on a halo orbit at the Lagrangian point L2 of the Sun-Earth System (SEL2). This region of space is one of several where the gravitational fields of the Earth and Moon are in equilibrium, providing the spacecraft with stability and minimal fuel consumption for a long lifetime.

The spacecraft’s estimated lifespan is four years. During that time, the observatory will observe about 1.2 million stars in a patch of sky in the constellations of Swan and Lyra, sending about 169 GB of data back to Earth daily.

The area was previously the subject of research by the Kepler telescope, which launched in 2009. Kepler has observed half a million stars and discovered 2,392 exoplanets. Although the telescope detected several Earth-group planets until 2018, when it was switched off, none were potential Earth doppelgangers. 

By comparison, the Earth 2.0 telescope will observe 1.2 million dwarf stars.

Seven Eyes of the “Earth 2.0” Observatory

Earth 2.0 will carry seven 30-centimetre telescopes. Six of them will search for planets using the transit method, using the characteristic changes in the brightness of a star when a planet passes in front of it.

The seventh telescope is designed to search for gravitational microlensing events, in which a star’s gravitational field focuses light from a distant star behind it, temporarily increasing its brightness. By studying the brightness pattern, astronomers can tell if the star has a planet orbiting it.

This seventh instrument will also be able to detect free-floating planets, thus helping to shed light on these strange, lonely objects that have been ejected from their star systems or formed in interstellar space. It will be the first microlensing gravitational telescope to operate from space if successfully launched.

Chinese scientists believe that the ET mission’s high sensitivity to detect signals of minor planet transits, long-term monitoring, and stable orbit will guarantee its scientific success.

Research Relay

Follow-up observations of the Earth 2.0 samples discovered by the ET mission will provide precise measurements of their mass, density and atmospheric composition, contributing to an in-depth study of their habitability characteristics.

Other telescopes will then search for biomarkers suggesting the presence of life, molecules such as methane and oxygen, and characteristic patterns of light absorption during photosynthesis. In addition, techno signatures that could indicate the presence of civilisation signals, such as industrial pollutants such as chlorofluorocarbons and even narrowband radio transmissions, will be searched for.

Moreover, studying many different exoplanet samples will contribute to a better understanding of the formation and evolution of these types of planets. ET’s extensive high-precision, high-frequency, and long-baseline photometric data will contribute to research in astroseismology, galactic archaeology, time-domain astronomy, double stars, and double black holes.