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According to foreign media reports, NASA held a press conference at 2 p.m. EST on June 7 (2 a.m. Beijing time on June 8) and announced two important discoveries about Mars: 1. The Curiosity Mars rover found organic molecules in a 3 billion-year-old sedimentary rock near the surface of Mars, indicating that ancient life may have existed on Mars;

2. It was found that the methane content in the Martian atmosphere fluctuates seasonally, or is related to modern Martian life. While not enough to say that life must have existed on Mars, these discoveries bode well for future exploration of the Martian surface and subsurface.

Both new findings were published June 8 in the journal Science.

Organic molecules are made up of hydrocarbons and may also include oxygen, nitrogen, and other elements. Although often associated with life, organic molecules can also be produced through non-biological processes and are not necessarily evidence of the existence of life.

"Mars is telling us with these new discoveries that we will stay on course and continue to search for evidence of life." Thomas Zurbuchen, deputy administrator for the Science Mission Council at NASA's headquarters in Washington, said, "I believe that current and future programs will lead to more amazing discoveries on Mars." ”

"Curiosity has not yet determined the origin of these organic molecules." Jennifer Eigenbrode, lead author of one of the two papers and NASA's Goddard Space Center, noted, "Whether the organic matter in Martian soil is a record of ancient life, food for living things, or unrelated to life, it can provide chemical clues about the Martian environment and evolutionary processes." ”

Although the surface of Mars is not suitable for life today, there is clear evidence that the Martian climate in ancient times once allowed liquid water to accumulate on the surface and form lakes. As far as we know, liquid water is essential for the existence of life. Data collected by Curiosity shows that billions of years ago, a lake in Gale Crater contained everything necessary for life, including chemical building blocks and energy sources.

"The surface of Mars is exposed to cosmic radiation. Both radiation and harsh chemicals can break down organic matter. "The discovery of ancient organic molecules in the top 5 centimeters of sedimentary rocks formed during the habitable period of Mars bodes well for us." In future missions, we will continue to dig down to learn more about the origin of organic molecules on Mars. ”

"ESA's ExoMars rover will dig even deeper, down to two metres underground." "So it's possible to dig up rocks that haven't been exposed to severe space radiation." ”

"There is also a possibility that the Mars Space Life Rover will find living life. But even if they can't be found, just analyzing the changes in organic matter from the surface to the depths of the ground is enough to make a startling discovery. ”

Methane on Earth is capable of being in the form of "combustible ice". And what about on Mars?

In the second paper, the scientists describe the seasonal fluctuations in methane levels observed in the Martian atmosphere over the last three Martian years (about six Earth years). The fluctuation was detected by Curiosity's Sample Analysis at Mars.

This methane may come from the chemical reaction between water and rocks, but scientists have not ruled out the possibility of biological involvement. Previously, scientists had only found methane in the form of large-scale, irregular plume jets in the Martian atmosphere. The new findings show that the small amount of methane contained in Gale craters increases and peaks in the warm summer months before declining again in the winter, year after year.

This finding is important because it will help narrow down the range of possible sources of methane. Methane on Earth is mainly associated with biological activities, from wetlands, farmland, livestock, and many more. It is not yet possible to confirm whether methane on Mars is associated with living things. However, the discovery of seasonal fluctuations in methane may rule out some geological explanations.

"This is the first time we've found some kind of repetitive phenomenon in our observations of methane, so it's helpful for our understanding of it." Chris ebster, lead author of the second paper and NASA's Jet Propulsion Laboratory, points out that "it's all thanks to Curiosity's longevity." Without its long service, we would not have been able to detect this seasonal pattern. ”

Methane in the Martian atmosphere has been a hot topic in scientific research. Methane cannot remain in the atmosphere for long periods of time. Since methane is always present in the Martian atmosphere, there must be a constant source of methane. Considering the connection between methane and living things on Earth, scientists must solve this Martian mystery.

Curiosity has been looking for traces of methane in the Martian atmosphere since it landed in Gale Crater at Mars' equator in 2012. It was found that methane levels in the northern hemisphere rose to just over 0.2 parts per billion in the winter and to 0.6 parts per billion in the summer. The research team believes that this methane may be stored in the form of ice

The team has not yet been able to confirm the source of methane, but believes that one explanation can be ruled out: sunlight can break down carbon-containing molecules (organic molecules) in meteorites on the surface of Mars, resulting in methane. Dr. Webst noted that the seasonal variation of UV light is not large enough to cause this level of change in methane concentrations.

This low-angle selfie of Curiosity captures it drilling a sample of a target rock in Mount Sharp, Gale impact crater.

To find organic matter in Martian soil, Curiosity drilled samples of sedimentary rocks, aka mudstones, in four areas of Gale Crater. These mudstones were formed from sediment accumulated at the bottom of ancient lakes over billions of years. The rock samples drilled are analysed by the Mars Sample Analyzer. The instrument heats the sample in an oven above 500 degrees Celsius, which releases the organic matter from the powdery rock.

The Mars Sample Analyzer detected small organic molecules, fragments of large organic molecules that are difficult to evaporate easily, from the material released from the mudstone samples. Some fragments contain sulfur. In the same way that sulfur is added to tires to increase durability, these fragments are also more stable and durable because of the presence of sulfur, according to Egenbrod.

The results also showed that organic carbon was in the order of 10 parts per million, and possibly more. This is close to the amount of carbon detected in Martian meteorites and about 100 times the amount of organic carbon previously detected on the surface of Mars. The identified molecules include thiophene, benzene, toluene, and others, as well as short carbon chains such as propane and butene.

In 2013, the Mars sample analyzer found some chlorine-containing organic molecules in the rocks deepest part of Gale Crater. The new discovery further enriches the types of molecules found in ancient lake sediments on Mars and helps explain why these molecules have survived to this day.

The discovery of methane in the Martian atmosphere and the discovery of organic molecules preserved from ancient times near the surface of the Earth have boosted scientists' confidence that NASA's 2020 Mars rover and ESA's ExoMars rover will also find more organic matter on the surface and shallow surface of Mars.

"Do these findings indicate the existence of life on Mars?" Michael Meyer, chief scientist for NASA's Mars exploration program, asked rhetorically, "We don't know yet." But these results show that we are on the right track. ”

The research was sponsored by the Mars Exploration Mission of the Science Mission Directorate at NASA Headquarters. The Goddard Space Center provided the Mars sample analyzer. The Jet Propulsion Laboratory is responsible for building the rover and managing the project for the Science Mission Council.

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A few words from the author's comment:

The organic analysis instrument of "Curiosity" is actually a relatively simple instrument, which decomposes macromolecular organic matter by heating and allows them to be released, and then can analyze simple organic molecules.

For example, this time: thiophene, benzene, toluene, and so on.

The organic matter that is actually contained in the soil is likely to be more complicated than these because of the heating.

Whether it is life or not is not clear.

Surely someone will say: why not launch a more powerful detection instrument? This organics analysis instrument is too simple, right?

Because Curiosity is already the limit of current technology, or close to it. It was launched in 2011 and is currently in 2018, and in just 7 years, there has been no particularly qualitative change in aerospace engineering. Our science is not as advanced as it seems.

It may take decades to find out if there is life or not.

I hope that our country can also contribute to this project.

Also, if life on Mars is really discovered, or if life ever existed, it is not necessarily a good thing for us (humans).

The more complex the discovery of life, the more bad news it becomes......

Because that means the starry sky is full of life...... This question has already been explained in , so I will not repeat it again.