Asteroid found more than 20 amino acids, can it be said to have life?

Text ｜ "China Science News" reporter Gao Yali Shen Chunlei Zhao Guangli

Recently, the Ministry of Literature and Arts of Japan said that more than 20 amino acids were detected in samples collected by the asteroid detector "Bird 2".

These samples come from the "Dragon Palace" in 2020 to the small planet "Dragon Palace" in 2020.

According to Kobayashi Xianzheng, a honorary professor of celestial biology at Yokohama National University in Japan, a variety of amino acids "unprecedented" on the planet outside the earth may even imply that there is life outside the earth.

Is the amino acid discovered this time so amazing? When a number of experts responded to the "China Science News", it was not the first time that human beings found amino acids in external materials, and it is difficult to use "or not life" to summarize new discoveries in outdoor exploration.

However, the sample brought back by "Bird 2" can help scientists understand the important scientific issues of the origin of the Early earth life, understand what the earth may be like in the predecessor, and when there is no life participation, the first batch of the first batch How is protein formed.

Not the first discovery

In response to the amino acids detected on the surface sample of the "Dragon Palace", Ji Jianghui, a researcher at the Zijinshan Observatory of the Chinese Academy of Sciences, said that this is not the first time that scientists have found amino acids outside the earth.

In the Mindson meteorite falling in Australia in 1969, scientists discovered more than 100 amino acids, but because meteorites may be contaminated by the earth, the existence of external amino acids is insufficient.

In addition, scientists have discovered the simplest amino acids -glycine in Renma B2, Orion KL and W51.

In 2015, the Ferle lander carried by Rosetta spacecraft found a key component of life such as nitrogen and amino acids such as the comets of the Churpov -Grassi Burma.

Scientists have previously found amino acids in asteroid meteorite samples.

However, compared to the meteorites studied in the past, this kind of samples collected in the natural state in natural state are very special.

Moreover, these "Dragon Palace" samples are under the surface of the asteroids that are not eroded by the sun or cosmic rays, and the sample analysis is also carried out without exposing it to the earth's air.

Amino acid is part of protein. Where the original amino acids on the planet come from, there are two sayings: the formation of the earth and the formation of space.

One argument is that amino acids are brought from space to the earth through meteorites, and amino acids were detected in meteorites before; but there are also saying that the earth originally had amino acids, and the amino acids found on meteorites were attached to the earth.

Zhu Jin, the honorary curator of Beijing Astronomical Museum and chief scientist at the Scientific Communication Center of Beijing Science and Technology Research Institute, said that water and amino acids on the earth may come to the surface of the earth through the form of small asteroids (small celestial bodies). The discovery of "Bird II" is some kind of support for this view.

Not the only criterion for judgment

Whether there is life, amino acid is not the only criterion for judgment.

Shen Jianxun, a postdoctoral Institute of Geology and Earth Physics of the Chinese Academy of Sciences, pointed out that amino acids are divided into two types, which can synthesize biomromes and cannot synthesize biomromes. As long as there are organic substances with amino and carboxyls, they can be called amino acids in a broad sense.

"The amino acids in the currently discovered biomin protein are 23 alpha -amino acids with left -hand glory and specific branches. Except for some protein translated derivatives formed, other thousands of amino acids cannot be for Earth biology. The protein provides components, "Shen Jianxun emphasized.

According to reports, amino acids discovered in the "Dragon Palace" this time include the essential heterogeneity and pyrine for the human body.

In addition, scientists have discovered glycine as collagen materials and glutamic acid widely known as fresh ingredients, as well as a variety of non -protein amino acids.

"The structured protein known on the earth is synthesized by L -virus amino acids as basic components. This choice for left and right hands appears only in the life body. The amino acids formed by the non -life process in nature or laboratory are usually generally. "Levose 'and' right spin 'each account for half."

Shen Jianxun said that it is as if the brick does not necessarily mean that there must be buildings there. The chemicals that can be composed of life do not represent life, nor can it be inferred how long it will form life.

He pointed out that given that we only understand the characteristics of life on the earth, this may limit our predictions on the existence of alien life.

Therefore, it is difficult for us to summarize the new discoveries in exterior exploration with or not, and we can only describe these phenomena based on the complexity of the chemical system.

Asteroid detection is accelerating

There are so many asteroids in space, why do scientists focus on the "Dragon Palace"?

"Dragon Palace" is a small carbonic asteroid (Type C planet) with a diameter of about 900 meters. It is formed by many large and small stones relying on its own gravity.

Ji Jianghui said that according to the observation of the "Dragon Palace" before the "Bird 2", this asteroid has the traces of hydraulic minerals inside. Asteroid.

Shen Jianxun pointed out that the high exterior amino acid diversity and possible interstellar transmission pathway is indeed an exciting thing in the celestial biology community. molecular.

Therefore, the discovery of the "Dragon Palace" has stimulated the motivation and mission of scientists for the detection of Mars' life signal.Asteroid detection has always been a popular research direction.In addition to Japan's "Bird 2", in 2023, the US detector Osiris -REX will collect samples from a small planet "Binu" and return it back to Earth.

Zhang Rongqiao, the chief designer of China Mars Exploration Mission Engineering for the first time, said in an interview with the media that Tianwen IV detectors have entered the initial development stage and are expected to be launched in 2025.sample.

"China Science News" (2022-06-14 The first edition of the original title "Amino acid is not equal to life")

Edit | Zhao Lu

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