[Creative Cultivation Program] What efforts has mankind made to search for habitable planets outside the Earth?

Author: Wang Zifeng

Review: Liu Qian

On June 20, NASA announced that they had discovered two "new worlds" that may contain rocky minerals. They orbit our neighboring star, only 33 light-years away from Earth.

The planet HD 260655 b is 1.2 times the size of Earth and twice its mass, and orbits its star every 2.8 days.

The planet HD c is 1.5 times the size of Earth and 3 times its mass, and orbits its star every 5.7 days.

Based on their size, mass and density, it is not difficult to judge that they may all be rocky planets, but due to their high temperatures, it is difficult to sustain life.

Even so, the two planets are worth studying. They are close to Earth and orbit bright stars. If we analyze the spectrum of starlight, we can reveal what molecules are present in their atmospheres.

It’s 2022. How is humanity’s plan to find Earth 2.0 going?

You may have always been curious about why we are constantly trying to find a new home.

It's instinct, but also helplessness.

Exploring space is a natural pursuit driven by curiosity, and at the same time, it is also to relieve environmental pressure and avoid astronomical disasters.

The world's population has been growing explosively and will continue to grow like dumplings in the future. Some people predict that by the year 2600, the world will become crowded and shoulder to shoulder.

Throughout the history of the Earth, there are countless disasters testing us, such as solar eruptions, celestial body collisions, magnetic pole reversals, radiation bursts, etc. Any of these disasters can ruthlessly harvest human civilization at the touch of a finger.

According to the results of observations of the solar system, the surfaces of the Moon, Mercury and Mars are densely covered with impact craters, and the Earth has also suffered large-scale destruction from celestial bodies.

Each destruction will lead to drastic environmental changes and large-scale biological extinction.

In order to continue the flame of civilization, we must find refuge in the universe.

As early as 1975, the United States implemented the Viking Plan to explore Mars. They launched two probes to Mars, one to the northern hemisphere of Mars, to collect rocks and sand, and to use a chromatograph to examine the chemical composition of the rocks and sand. As a result, no life was found on Mars, indicating that there is no life on Mars.

While exploring life on Mars, humans also focus on Venus. Although Venus is also close to Earth, its surface temperature is as high as 460 degrees, its atmospheric pressure is 90 times that of Earth, and there are strong air currents inside, so it is known as the hell planet.

In addition to exploring the planets within the solar system, humans have long shown a keen interest in planets outside the solar system.

As early as 1995, Swiss astronomers used the telescope of the Haute-Provence Observatory to discover the first exoplanet "Pegasus 51b" orbiting a sun-like star. 8 million kilometers away from the Pegasus star, people discovered a planet about the same size as Jupiter with an orbital period of 4.2 days. This proves that the solar system is not alone.

In 2010, the United States began to plan the Kepler project, with the goal of discovering Earth-like planets in the habitable zone of sun-like stars, that is, Earth 2.0.

At present, the United States' Kepler Space Telescope and TESS satellite have discovered more than 1,660 Earth-like planets.

The Spanish-German CARMENES project is also using a 3.5-meter telescope, combining infrared photometry with an optical echelle spectrometer, to search for Earth-like planets.

With the support of the Strategic Priority Research Program of the Chinese Academy of Sciences, more than 100 scientific researchers from major observatories, research institutes and technical universities in my country have also joined forces to carry out technical research and launch a census of Earth-like planets in the Milky Way.

At present, my country plans to launch a scientific satellite equipped with six independently developed transit telescopes with a diameter of 30 cm and a wide angle of 500 square degrees, and one microlens telescope with a diameter of 30 cm and a wide angle of 4 square degrees, to the Sun-Earth Lagrange L2 point, and conduct a large-scale census of terrestrial planets in the Milky Way using ultra-large field of view and ultra-high precision optical photometry.

This is the first time that we have combined the "transit method" and the "microlensing method", using two highly sensitive observation methods to detect asteroids. This allows us to superimpose observation data and greatly increase the search probability.

At present, a satellite team consisting of more than 200 astronomers from more than 30 universities and research institutes at home and abroad has formed the "Neighboring Habitable Planet Survey" project, which will enable mankind to obtain the largest sample library of Earth-like planets.

However, the search for the second Earth is not that easy. It needs to be at a moderate distance from the star, the radiation should not be too strong, and the appropriate gravity can give birth to a suitable magnetic field, tidal force and atmosphere, mineral-rich soil, and healthy water sources. These are all necessary conditions for the continuation of life.

The journey of mankind is to the sea of ​​stars. We still have a long way to go in finding habitable planets outside the earth, but with the support of various cutting-edge technologies, that day should come as soon as possible.

References:

Xinhuanet: Two "super-Earths" only 33 light-years away were discovered;

People's Daily Online: Science and Technology: Looking for a second Earth, a second home? We have just started;

Science and Technology Daily: Detecting stars 32 light years away to find "Earth 2.0";

Chinese Academy of Sciences: Earth 2.0 Will the second home of mankind be the "Wandering Earth"?

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