Meteorites from Mars. What can Martian meteorites tell us about extraterrestrial life? What information did “Black Beauty” give?

Martian meteorite EETA79001

Martian meteorite- a rare type of meteorite that came from the planet Mars. As of November 2009, out of more than 24,000 meteorites found on Earth, 34 are considered Martian. The Martian origin of meteorites was established by comparing the isotopic composition of the gas contained in meteorites in microscopic quantities with data from an analysis of the Martian atmosphere made by the Viking spacecraft.

Origin of Martian meteorites

The first Martian meteorite, named Nakhla, was found in the Egyptian desert in 1911. Its meteorite origin and belonging to Mars were determined much later. Its age was also determined - 1.3 billion years.

These stones ended up in space after large asteroids fell on Mars or during powerful volcanic eruptions. The force of the explosion was such that the ejected pieces of rock acquired a speed sufficient to overcome the gravity of Mars and even leave the near-Martian orbit (5 km/s). Thus, some of them were caught in the Earth's gravitational field and fell to Earth as meteorites. Currently, up to 0.5 tons of Martian material per year falls on Earth.

Meteorite evidence of life on Mars

In 2013, when studying the MIL 090030 meteorite, scientists found that the content of boric acid salt residues necessary to stabilize ribose was approximately 10 times higher than its content in other previously studied meteorites.

Notes

Mars Meteorite Home Page(English) . JPL. - List of Martian meteorites on the NASA website. Retrieved November 6, 2009. Archived April 10, 2012.
Ksanfomality L.V. Chapter 6. Mars.
// Solar system / Ed.-state. V. G. Surdin. - M.: Fizmatlit, 2008. - P. 199-205. - ISBN 978-5-9221-0989-5. McKay, D.S., Gibson, E.K., ThomasKeprta, K.L., Vali, H., Romanek, C.S., Clemett, S.J., Chillier, X.D.F., Maechling, C.R., Zare, R.N.

At the beginning of December last year, we talked about the conclusions of scientists who came to the conclusion that life could very likely appear on Mars. In support of such amazing conclusions, they spoke about the presence of chemical elements generated by biological activity in a stone that they found... on Earth. According to experts, the Martian origin of the fragment discovered on July 18, 2011 is proven by its chemical analysis. “The rock contains extremely low levels of rare earth elements, which are characteristic of rocks on the surface of Mars,” they note in the published study. But how then could this stone from Mars get to us? Readers asked us the following questions:

— How could a stone of such small size be discovered on Earth? What mechanisms led to it leaving the Martian surface and reaching us? And vice versa, can a rock of N size from Earth end up on Mars?

— Please explain why Martian rocks fly away from the planet, contrary to all the laws of gravity, and fall to Earth?

— You say that the meteorite came from Mars. How could such a stone overcome the gravitational field of the planet? And can meteorites of terrestrial origin exist?

We asked these questions to Philippe Gillet of the École Polytechnique Fédérale de Lausanne, who was one of the study's co-authors. He explains it this way: “A relatively large object struck the Martian surface with sufficient force to throw fragments of Martian rock out of the planet’s atmosphere.” It's similar to how water splashes when you throw a stone into a pond.

Experts even have relatively accurate data on how strong an impact is required to throw rock fragments into space. “The speed of an object is proportional to the gravitational force of the planet,” explains Philippe Gillet. “We know that on Mars it is 8-10 kilometers per second. Based on this parameter, the scatter and the crystal structure of the rock, we can estimate the mass of the object that hit the Martian surface and even calculate the size of the crater it left.”

“We believe that launching a rock the size of the Tissint meteorite into space would require an object ranging from hundreds of meters to several kilometers in diameter to hit the surface of Mars,” he continues. As a result, the stones receive a powerful impulse and follow a ballistic trajectory that can take them beyond the gravitational field of Mars. Stones wander through space until they fall into the gravitational field of some other celestial body. While traveling through space, these rock fragments are subject to active bombardment by solar particles, from which they were previously protected by the planet's soil. “This stream of particles affects the substance and creates special isotopes that can be counted and thereby determine the total time the stone spent in space,” says Philippe Gillet. “The Tissint meteorite wandered for approximately 700 thousand years before reaching the earth’s surface.”

Fragments of earth rocks are also floating around in space.

If such mechanisms work on Mars, do they also work on Earth? In other words, is it theoretically possible to stumble upon pieces of our good old Earth that were thrown onto other planets after a meteorite hit? “Of course,” replies Philippe Gillet. Even if those rare studies of the surface of other planets have not yet shown this. But they certainly exist there, because this kind of event (an impact from a sufficiently large and fast-moving object to eject rock fragments into space) occurred more often on Earth than on Mars. In fact, everything depends on the mass of the planet: the larger the celestial body, the greater the force of attraction it exerts on objects in its surroundings.

And since the Earth's mass is ten times greater than that of Mars, it attracts more wandering space objects. “On Earth, a meteorite with a diameter of 100 meters falls approximately once every five centuries. A meteorite with a diameter of 5 kilometers hits Earth once every 10-50 million years,” says Philippe Gillet. For comparison, the meteorite that ended the age of dinosaurs on Earth 65 million years ago was 10 kilometers in diameter. “Such an event occurs once every 100-500 million years,” the scientist believes. After such an impact, a huge amount of earth rock ended up in space...

And they are considered incredibly valuable samples, since they represent unique time capsules from the geological past of Mars. These meteorites by their nature provide us with samples of Mars without any space missions.

"While robotic missions to Mars continue to attempt to shed light on the planet's history, the only samples from Mars available for study on Earth are Martian meteorites," said study lead author Lauren White of NASA's Jet Propulsion Laboratory. “On the ground, we can use several analytical techniques to look deeper into the meteorite and shed light on the history of Mars. These samples may hold clues to their planet's habitable past. As more and more Martian meteorites are found, the cumulative research provides more attributes of ancient habitation on the planet. "In addition, if these meteorite studies are confirmed by modern robotic observations of Mars, the mystery of the planet and its wet past may be solved."

In their study, the scientists describe features associated with Martian clay deposits - microtunnels similar to those found in samples Y000593. Compared to terrestrial samples, the Martian forms appear to be very similar to the biohydrothermal textures of basalt glasses. Basically, this means that the Martian meteorite contains features that resemble mineral formations created by bacteria on Earth.

Another factor is the discovery of nanometer- to micron-sized balls located between layers of rock in the meteorite. These spherules are distinct from the minerals within the rock and are rich in carbon, which may indicate biological interactions within the rock material.

Could this be evidence of Martian bacteria chewing Martian rocks? Unfortunately, this conclusion cannot be drawn from the study, so the researchers avoid the word “life” in their works - replacing it with “biogenic origin” and “biotic activity.”

“We cannot rule out the possibility that carbon-rich areas may be the product of non-biotic mechanisms,” the scientists write. So-called abiotic mechanisms mean that the effects are not caused by microbial life, but by chemical reactions in the geology of the stone. “However, textural and compositional similarities to features in terrestrial samples that are clearly interpreted as biogenic suggest the intriguing possibility that Martian features are shaped by biotic activity.”

Other astrobiologists literally supported the scientists’ caution with applause. "It's good that they didn't raise a false alarm and speculate about 'life on Mars' by admitting they don't know for sure what the origins of these channels are," said Louise Preston from the UK.

“This is not a smoking gun,” White said. - We can never rule out the possibility of terrestrial contamination. But these features are nevertheless interesting and show that further research on meteorites needs to be continued.”

With the controversial 1996 ALH84001 in mind, many researchers react aggressively to any research that emerges into the question of life on Mars and other planets, and skepticism is often too high. Therefore, until we can find and analyze DNA of extraterrestrial origin, or find intact samples on Mars, work on the question will be presented as “exciting, but not definitively verified.”

The Martian origin of meteorites was established by comparing the isotopic composition of the gas contained in meteorites in microscopic quantities with data from an analysis of the Martian atmosphere made by the Viking spacecraft.

Origin of Martian meteorites

Meteorite evidence of life on Mars

In August 1996, the journal Science published an article about a study of the ALH 84001 meteorite, found in Antarctica in 1984. Isotope dating showed that the meteorite originated 4-4.5 billion years ago, and was thrown into interplanetary space 15 million years ago. 13,000 years ago, a meteorite fell to Earth. Studying the meteorite using an electron microscope, scientists discovered microscopic fossils that resemble bacterial colonies, consisting of individual parts approximately 100 nm in size. Traces of substances formed during the decomposition of microorganisms were also found. The work was received ambiguously by the scientific community. Critics noted that the sizes of the found formations are 100-1000 times smaller than typical terrestrial bacteria, and their volume is too small to accommodate DNA and RNA molecules. Subsequent studies revealed traces of terrestrial biocontaminants in the samples. Overall, the argument that the formations are bacterial fossils does not seem convincing enough.

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Excerpt characterizing the Martian meteorite

It was impossible to fight when information had not yet been collected, the wounded had not been removed, the shells had not been replenished, the dead had not been counted, new commanders had not been appointed to replace the dead, and people had not eaten or slept.
And at the same time, immediately after the battle, the next morning, the French army (due to that rapid force of movement, now increased as if in the inverse ratio of the squares of the distances) was already advancing by itself on the Russian army. Kutuzov wanted to attack the next day, and the whole army wanted this. But in order to attack, the desire to do so is not enough; there needs to be an opportunity to do this, but this opportunity was not there. It was impossible not to retreat to one transition, then in the same way it was impossible not to retreat to another and a third transition, and finally on September 1, when the army approached Moscow, despite all the strength of the rising feeling in the ranks of the troops, the force of things demanded so that these troops march for Moscow. And the troops retreated one more, to the last crossing and gave Moscow to the enemy.
For those people who are accustomed to thinking that plans for wars and battles are drawn up by commanders in the same way as each of us, sitting in his office over a map, makes considerations about how and how he would manage such and such a battle, questions arise as to why Kutuzov didn’t do this and that when retreating, why he didn’t take up a position before Fili, why he didn’t immediately retreat to the Kaluga road, left Moscow, etc. People who are used to thinking like this forget or don’t know those inevitable conditions in which the activities of every commander in chief always take place. The activity of a commander does not have the slightest resemblance to the activity that we imagine, sitting freely in an office, analyzing some campaign on the map with a known number of troops, on both sides, and in a certain area, and starting our considerations with what some famous moment. The commander-in-chief is never in those conditions of the beginning of some event in which we always consider the event. The commander-in-chief is always in the middle of a moving series of events, and so that never, at any moment, is he able to think through the full significance of the event taking place. An event is imperceptibly, moment by moment, cut into its meaning, and at every moment of this sequential, continuous cutting of the event, the commander-in-chief is in the center of a complex game, intrigue, worries, dependence, power, projects, advice, threats, deceptions, is constantly in the need to respond to the countless number of questions proposed to him, always contradicting one another.
Military scientists tell us very seriously that Kutuzov, much earlier than Filey, should have moved troops to the Kaluga road, that someone even proposed such a project. But the commander-in-chief, especially in difficult times, faces not one project, but always dozens at the same time. And each of these projects, based on strategy and tactics, contradicts one another. The commander-in-chief's job, it would seem, is only to choose one of these projects. But he cannot do this either. Events and time do not wait. He is offered, let’s say, on the 28th to go to the Kaluga road, but at this time Miloradovich’s adjutant jumps up and asks whether to start business with the French now or retreat. He needs to give orders now, this very minute. And the order to retreat takes us off the turn onto the Kaluga road. And following the adjutant, the quartermaster asks where to take the provisions, and the head of the hospitals asks where to take the wounded; and a courier from St. Petersburg brings a letter from the sovereign, which does not allow the possibility of leaving Moscow, and the rival of the commander-in-chief, the one who undermines him (there are always such, and not one, but several), proposes a new project, diametrically opposed to the plan for access to the Kaluga road; and the forces of the commander-in-chief himself require sleep and reinforcement; and the venerable general, bypassed by a reward, comes to complain, and the inhabitants beg for protection; the officer sent to inspect the area arrives and reports the exact opposite of what the officer sent before him said; and the spy, the prisoner and the general doing reconnaissance - all describe the position of the enemy army differently. People who are accustomed to not understanding or forgetting these necessary conditions for the activity of any commander-in-chief present to us, for example, the situation of the troops in Fili and at the same time assume that the commander-in-chief could, on September 1st, completely freely resolve the issue of abandoning or defending Moscow, whereas in the situation of the Russian army five miles from Moscow this question could not have arisen. When was this issue resolved? And near Drissa, and near Smolensk, and most noticeably on the 24th near Shevardin, and on the 26th near Borodin, and on every day, hour, and minute of the retreat from Borodino to Fili.

Geologists who analyzed 40 meteorites that fell to earth from Mars have revealed some of the secrets of the Martian atmosphere hidden in the chemical signatures within their structure. The results of their research were published April 17 in the journal Nature and suggest that the atmosphere of Mars and the atmosphere of Earth began to differ significantly from each other at a point in time when the solar system was 4.6 billion years old. These studies, along with studies by Mars rovers, should help scientists understand whether life could exist on Mars and what the local water was like.

The research was led by Heather Franz, a former postdoctoral researcher at the University of Maryland, College Park, who is now working with the Curiosity rover science team, along with James Farquhar, a geology professor at the University of Maryland. The researchers measured the sulfur composition of forty Martian meteorites, a significantly higher number than other studies. In general, more than 60 thousand meteorites have been found on Earth, and only 69 of them are believed to be parts of solid Martian rocks.

Martian meteorite EETA79001. Source: Wikipedia

In general, Martian meteorites are hard igneous rocks that formed on Mars and were thrown into space when an asteroid or comet crashed into the red planet. After some travel in outer space, meteorites managed to fly up to the Earth and even fall on its surface. The oldest Martian meteorite in the study is approximately 4.1 billion years old, which corresponds to a time when the solar system was in its infancy. The age of the youngest meteorites studied ranges from 200 to 500 million years.

Studying Martian meteorites of different ages can help scientists examine the chemistry of the Martian atmosphere as it has changed throughout its history and understand whether it was ever suitable for life. Earth and Mars share similar elements that are found in living organisms on Earth, but conditions on Mars are much less favorable due to dry soil, cold temperatures, radioactive radiation and ultraviolet radiation from the Sun. However, evidence has already been found that some Martian geological features could only have formed in the presence of water, which is an indirect sign of moderate climate conditions in the past. Scientists do not yet understand exactly what conditions contributed to the existence of liquid water. Most likely, these are greenhouse gases released into the atmosphere by volcanoes.

Internal structure of the Nakhla meteorite. Photo from 1998. The meteorite was discovered in 1911 in Egypt. Source: NASA

Sulfur, which is widespread in Martian soil, may have been present as part of greenhouse gases that warmed the planet's surface, and may have provided food for microbes. This is precisely why scientists analyzed sulfur particles in Martian meteorites. Some of it could have gotten into the meteorite from molten rock or magma that poured to the surface during volcanic eruptions. On the other hand, volcanoes also released sulfur dioxide into the atmosphere, where it interacted with light and other molecules and then settled on the surface.

Sulfur has four naturally occurring stable isotopes, each with its own unique atomic signature. And sulfur itself is chemically universal. Interacting with many other elements, characteristic changes also remain in its structure. Scientists by analyzing sulfur isotopes in a meteorite can determine whether it came from below the surface, atmospheric dioxide or a product of biological activity.