Secrets of the Red Planet. The international spacecraft "Phoenix" has started the first experiments. The minimum task is to detect traces of water in the Martian soil, which, as you know, is the basis of terrestrial life.
The "Phoenix", which landed on Mars at the end of May, landed near the polar cap, where, scientists suggest, there may be underground water, more precisely, ice. His manipulator arm loaded a portion of the Martian soil into the furnace: it will slowly heat up to 1000 ° C, and the onboard mass spectrometer - to try to detect traces of water and small organic molecules in the evaporation from the soil. After that, devices for electrochemical analysis will determine the salinity and acidity of the soil. For all experiments, the Phoenix has a maximum of 150 days: even under an ideal set of circumstances, the Martian polar winter will then kill it - the ship will be covered with “dry ice” from carbon dioxide.
NASA goes for water
Despite the sensationalism of the current Phoenix expedition 1 is just another step in the history of Mars missions, part of a 50-year experiment to search for life outside the Earth, an experiment in which astronomy, geology, physics, chemistry and biology are intertwined. In addition, research in space biology goes hand in hand with the study of terrestrial extremophiles — organisms that can reproduce in severe frost, live in saline soil, drawing oxygen and energy from chemical sources.
There is a hypothesis: for the dunes to become rocks, water was needed
NASA and other organizations involved in the project call their strategy Follow the water. The fact is that water is a key factor in the existence of life. Living things can live without oxygen in the atmosphere, as can many terrestrial anaerobic bacteria; can live without solar energy and photosynthesis: there are terrestrial bacteria that live by oxidizing sulfur and other types of chemosynthesis; can live in dry frozen soil: bacteria also live in the McMurdo Desert in Antarctica, which feed on microscopic worms (nematodes). Finally, extremophiles can live in boiling water, acids and alkalis, even in a nuclear reactor. But living beings cannot live without liquid water. And just with it on Mars there are some problems.
Dead planet?
The fact is that due to the low atmospheric pressure (100 times less than Earth's), liquid water on the surface of Mars instantly evaporates. Mars is a small planet, its gravity cannot hold a dense atmosphere, while the Martian one consists mainly of carbon dioxide with an admixture of nitrogen and argon. Nevertheless, there are large polar caps on Mars, consisting mainly of water ice. On top of the cap is a layer of frozen carbon dioxide (the same “dry ice” that ice cream sellers use). Mars is one and a half times farther from the Sun than the Earth, and the temperature of its surface, poorly protected by the atmosphere, jumps from +20 O up to -140 O WITH.
It would seem that these conditions rule out life on Mars. But observations made by previous missions have shown that large rivers once flowed through Mars, from which traces remain - meandering valleys and deltas with characteristic deposits. How could this be? And so: the tilt of the axis of rotation of the Red Planet changed, and the climate changed with it. Millions of years ago it could have been warmer and much wetter. Moreover, scientists do not rule out the possibility that 3-4 billion years ago, when life appeared on Earth, it could also appear on Mars.
Hopes and disappointments
The first hopes that Mars was inhabited appeared at the end of the 19th century. In the years 1877-1890, the Italian scientist Giovanni Schiaparelli compiled maps of Mars, on which he noted geological structures, which he called canali (channel, strait). Due to the inaccurate translation into English (the English word channel means "artificial channel"), many people have decided that we are talking about channels built by intelligent beings. The American astronomer Percival Lovell developed colorful speculations about the great civilization of the Martians, who created a giant network of canals to irrigate the arid planet with water from the polar caps. Then in 1909 the French astronomer Eugène Antoniadi showed that the "channels" were an optical illusion. Despite this, the image of the Martians and the ancient civilization of the Red Planet has steadily entered the world of science fiction literature.
Most missions to Mars have been unsuccessful. The first spacecraft to approach Mars in 1963 was the Soviet Mars 1, but it lost contact with the Earth before reaching Mars. The first spacecraft to land on Mars in 1971 was also the Soviet Mars-3, but it lost contact with the Earth after landing. In 1965, the American probe Mariner 4 flew over Mars and showed that there are no channels on Mars, there is no magnetic field that could protect living organisms from ultraviolet radiation, and low atmospheric pressure does not allow the existence of liquid water. Scientists have pronounced a verdict: Mars is a completely dead cold world, like the moon. However, in 1971, the Mariner 9 probe took photographs of valleys that were definitely river deltas millions of years ago.
Are we descendants of Martians?
It is even possible that the spores of ancient bacteria were transferred from Mars to Earth by meteorites: space "travelers" falling on the planet pulled out stones from it, which flew into outer space and after some time found themselves in the Earth's gravity zone and fell on it. surface. 34 such meteorites were found, and on three of them (found in Egypt, India and Antarctica) formations were found that some researchers (in particular, Professor Chris McKay, one of the authors of the Phoenix experiments) interpreted as possible traces of "nanobacteria ". If bacteria lived on ancient Mars, then as a result of the “cosmic billiard” of Martian meteorites, they could get to Earth and become the distant great-ancestors of Homo sapiens, Homo sapiens.
Vikings on Mars
One of the most important Martian missions was the expedition of the American ships Viking 1 and Viking 2, which landed on the planet in 1976. Their main task was to detect bacteria. One of the experiments seemed to give hope that there are microscopic creatures in the soil of Mars. However, science, as you know, assumes the repeatability of the result, but it was not possible to repeat the result.
True, the Vikings landed in that region of the planet where there could be no traces of underground water. Phoenix “took into account” this mistake, in addition, it is equipped with ultra-modern devices for detecting water, light organics, oxidizers and salinity. The decision on how to equip the "Phoenix" was made taking into account the study of similar regions of the Earth - the frosty high-altitude deserts of Antarctica. So the hope that the Phoenix will find something that will reduce the likelihood of our absolute loneliness in the solar system remains.
The New Times asked the world's leading space biologists involved in the development of Martian missions to assess the likelihood of possible - even if in the past - life on Mars.
One of the stated goals of the Phoenix mission is to determine whether Mars is habitable. In the past, various biologists (for example, Edward Wilson) compared Mars to the dry valleys of McMurdo in Antarctica, where extremophiles live - bacteria, archaea and nematode worms. Do you think this comparison is justified? What happens if you move the organisms from McMurdo to the Martian environment?
Andrew Knoll: Places like the dry valleys of Antarctica are more like the landing site of the Phoenix than other places on Earth. But it's important to remember the differences. In conditions of low temperatures and low atmospheric pressure on modern Mars, liquid water is unstable (that is, water can exist either as steam or as ice, but not as a liquid. - The New Times). Oxygen is present in negligible amounts - certainly too low to support the respiration process that you, me, other animals, such as nematode worms, need. Therefore, I think that if you export the organisms of the terrestrial dry valleys to Mars, then they will quickly die there.
Chris McKay: There are indeed nematode worms in Antarctica, but they live in the lowlands, in the "wet" permafrost, which forms a thick layer of soil saturated with liquid water every summer. We have not found nematodes high above sea level, in regions of Antarctica similar to Mars. However, our research last summer showed that bacteria (and probably archaea) exist in Mars-like terrestrial soils.
Andrew Knoll: There is another important point: on Earth, biologically extreme ecosystems are usually surrounded by a more habitable world, as a result, extreme zones receive ... well, what are the "subsidies" from "normal" ecosystems in the form of nutrients and organisms. There is no such thing on Mars, extreme ecosystems are the only ones on the planet…
In the bowels of the earth, at a depth of up to 3 kilometers, the so-called endoliths live - bacteria, archaea and fungi. Is it possible that something similar exists on Mars?
Chris McKay: It is unlikely that we will be able to drill deep on Mars, at least in the foreseeable future: drilling to a depth of one kilometer or more will only be possible if a permanent research base is established on Mars.
Let's say Phoenix or one of the next expeditions finds living microorganisms on Mars or evidence of their existence in the past. How will this affect the development of science?
Chris McKay: It's one thing if Martian life turns out to be related to Earth life (that is, they had a common ancestor), it's another thing if Martian life turns out to be alien, a real second genesis of life. If we can also obtain the organic remains of this life of a different origin, then we can study its alternative biochemistry and genetics and compare it with our own, based on protein biochemistry and DNA genetics. There are fundamental questions regarding the origin of life that we will only be able to answer when we have more than one type of life to study.
Is Mars our only hope for 'overcoming loneliness' in the solar system?
Leslie Tamppari: Europa (Jupiter's moon) - suggests that hypothetically there could be some kind of life there too. Because it is believed that under the icy shell of Europa there is a layer of liquid water. Since Europa is also attracted and compressed by the gravitational effects of Jupiter and other large moons, volcanic activity can occur under its surface. If this is the case, such activity may provide an energy source for potential organisms. NASA is currently exploring the possibility of sending an expedition to Europe.
Professor Christopher McKay, one of the world's leading space biologists, is responsible for the biological side of the Phoenix mission and works at the NASA Ames Center in Sunnyvale, California. In addition to cosmobiology, Professor McKay studies extremophiles - organisms capable of surviving in extreme conditions. McKay has led expeditions to Antarctica, Death Valley and the Russian Arctic.
Professor Leslie Tamppari is one of the leaders of the Phoenix Expedition and works at the NASA Jet Propulsion Lab (JPL) in Pasadena, California. Leading scientist in the preparation of projects for the next missions to Mars, to Jupiter's moon Europa and to Saturn's moon Titan.
Professor Andrew Knoll is a space biologist and professor at Harvard University, USA. Works with Martian missions Spirit and Opportunity. Known for researching microfossils of the most ancient forms of life on Earth. Author of Life on a Young Planet: The First Three Billion Years of Evolution on Earth.
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1 Universities, research and commercial organizations in the USA, Canada, Switzerland, Philippines, Denmark, Germany, Great Britain and Finland take part in the mission.
