This “express” from Mars please check.

There was much research on Mars before the Mars rover landed, some of which relied on Martian meteorites. The International Meteorology Society’s website meteorite database contains more than 70,000 named meteorites worldwide, including 276 Martian meteorites. Just last July, there was a multi-country stage of the “fire detection” drama. On July 20, the United Arab Emirates’ “Hope” Mars rover launched, on July 23rd, China’s “Sky Question One” Mars rover successfully launched, and on July 30, the U.S. “Stoun” Mars rover also began a “fire- ” tour.

Mars meteorite slices are pictured.

In fact, before the world’s “fire-detecting” and even before the earlier Mars rover “visited” Mars, Mars has sent its “messenger” to Earth – Mars meteorites. Of all the Mars meteorites named, the earliest is the “Chassigny” meteorite that fell in the Champagne-Arden region of France in 1815.

Recently, Hu Sen, an associate researcher in the Key Laboratory of the Institute of Earth and Planetary Physics of the Institute of Geology and Geophysics of the Chinese Academy of Sciences, and his collaborators also found The Quartz for the first time in Martian meteorites.

How on earth did Martian meteorites reach Earth, where they often “perch” on Earth, and how did they help humans “unlock” the mysteries of Mars?

Why is the chance of a Mars “messenger” coming so small?

Science and Technology Daily reporter logged on to the International Meteor Society website query found that as of August 2, 2020, the site’s meteorite database contained more than 70,000 named meteorites in the world, including 415 lunar meteorites, 276 Martian meteorites.

These days, however, outsiders, “body” is more pocket-sized. In the database, the heaviest Martian meteorite was a 1962 meteorite named “Zagami” that fell in The State of Katsina, Nigeria, weighing 18 kg, and the lightest was the “NWA 8116” meteorite found in Northwest Africa in 2007, weighing about 0.48 grams.

“Overall, the number of Martian meteorites found on Earth is very small, with a total weight of just over 200 kilograms.” Xu Weixuan, director of the Astrochemistry and Planetary Science Laboratory at the Zijinshan Observatory in Nanjing, Told Science and Technology Daily that a Martian meteorite is less likely to fall to Earth than other asteroid meteorites.

“Because of the larger planet, the debris from small impacts does nare that doesn’t fly into the gravitational field of Mars. The debris must fly at more than 5 km/s to escape from Mars to escape from its control. Not only that, but there’s an atmosphere on Mars that stops some debris, Xu said. Millions of years after orbiting Mars, those debris that are out of the hands of Mars will also be intersected with Earth’s orbit, captured by the Earth’s gravitational field, and survived through the Earth’s atmosphere before it can fall to the ground.

How to “verify the positive body” for the Martian meteorite

How do you determine whether a meteorite is from Mars?

“In the early days of the Martian meteorite study, measuring whether the composition of the Martian atmosphere was consistent with the gas in the Martian meteorite glass was one of the methods used to determine the identity of the meteorite.” Zhang Aixuan, a professor at Nanjing University’s School of Geosciences and Engineering, told Science and Technology Daily that when the Martian meteorite is cut open, there will be glass inside, which is the molten glass formed by the asteroid hitting Mars in high temperature conditions, which is covered with Martian gas.

After the launch of the U.S. Pirate seraprobe in 1975, it measured the Martian atmosphere and found that there were gas molecules such as carbon dioxide, nitrogen, argon, and argon. The scientists also tested the gas in the eETA79001 meteorite glass and found that the gas components released by the meteorite were exactly the same as those of the Martian atmosphere, so it was proved that the EETA79001 meteorite came from Mars. It is also the first Martian meteorite confirmed by humans.

“Another way is to measure the age of Martian meteorites.” Xu said that the “age” of Mars meteorites can be measured by measuring the radioactive isotope composition of many asteroids, many asteroids age about 4.5 billion years old, the age of lunar meteorites is about 34 billion years, and Mars is relatively large, 200 million years ago even volcanic activity, Mars meteorites are the most “young” for 200 million years, than “older” for about 2 billion years, “if the use of radioisotope decay to measure a piece of the age of a meteorite is likely to come from the younger. Xu said.

However, this evidence alone is not enough. When scientists probed nano-scale compounds inside Martian meteorites and the isotopes they contained, they found that they contained hydrogen, nitrogen, oxygen, sulfur and other elements, the content of these specific elements, but also to the identification of Martian meteorites, “Mars meteoriteoxygen isotope composition and the moon, the Earth are different, such as Mars meteoriteoxygen 17, oxygen 18 is about three thousandths of the Earth.” Xu said.

Zhang said that when celestial bodies form, the distance from the sun will lead to different temperatures of the celestial bodies, thus affecting the proportion of their internal elements. Mars meteorites are composed of olivine, flint and long stone, and their ferromanganese ratio will be lower than that of the rocks of the earth and the moon.

Where is the “paradise” of finding Martian meteorites

As can be seen in the meteorite database on the International Meteor Society website, Martian meteorites are largely distributed in deserts and Antarctica.

“In fact, where mars meteorites fall is random, but there are more Martian meteorites currently found in the desert and antarctica.” Zhang said.

“There are more Martian meteorites found in Antarctica because the Antarctic has a thick ice sheet, very cold, dry, meteorites will fall down will be buried by ice and snow, can be long-term preservation. At the same time, the Antarctic ice sheet in the flow of mountains will stop, under the influence of the wind, local ice rapidly melt, meteorites will reveal the ice. Zhang said.

Some scholars have found that the rich areas of Antarctic meteorites are mostly distributed along the edge of the East Antarctic ice sheet, mainly the transverse mountain region and the eastern edge of the East Antarctic.

Why do Martian meteorites appear in the desert? Lin Yangting, a researcher at the Institute of Geology and Geophysics of the Chinese Academy of Sciences, said the desert is very dry and there is no problem with meteorites being preserved in the desert for hundreds of thousands of years, but there is no ice in the desert to carry meteorites, so meteorites will not be concentrated in some part of the desert relative to Antarctica.

Meteorites hide the secrets of Mars.

Over the years, scientists from around the world have been trying to find clues to the evolution of Mars and life on Mars.

In 1996, NASA scientists reported that they had found a microbial-like structure in al-AlH 84001, a Martian meteorite in Antarctica, which could be a biological “fossil” of Mars, evidence that life once existed on Mars. However, the subsequent study tends to believe that the structural form of this microbial-like organism is formed by geological action, and its organic components are contaminated from the Earth.

Although no evidence of the existence of life has been found, Mars meteorites also record information on the magma and atmospheric waters of Mars.

In 2014, Lin Yangting’s team published a study of the Martian meteorite GRV 020090. They found that the water content of the Martian mantle was very low, about one-tenth of the mantle, which means that Mars was very dry. At the same time, a lot of water escaped from Mars. The study suggests that about 3 billion years ago there was water on the surface of Mars. As Mars grew cold, part of the water ran away and some of it turned into underground glaciers and permafrost. If magma had erupted 200 million years ago, its heat could melt underground permafrost and glaciers into water, providing an environment conducive to life.

“We want to know what has happened to Mars; whether the visible, untouchable red planet has life; whether it’s suitable for human habitation, and hopefully Mars meteorites will give us more surprises.” Xu said.