Was there really life on Mars?
Scientists are eager to study the Martian soil, because the conditions on the Red Planet were the same as on Earth billions of years ago. Modelling and years of research on Mars have shown that it once had water on its surface, and the planet was surrounded by a dense atmosphere. Today, most of the atmosphere is gone, and the main goal of the researchers is to find traces of bacteria and organisms that could live on the planet while the conditions were favorable.
The history of the search for life – or its traces – on Mars began in 1965 with the launch of the American research apparatus “Mariner-4”, which flew around the planet in orbit and took pictures of about 1% of its surface. The first results disappoint scientists: the study showed that the planet has no rivers or oceans, and its surface is dotted with craters – this is evidence of the lack of tectonic activity in at least the last 4 billion years.
Astronomers then confirmed the hypothesis that there is no magnetic field on Mars that protects the Earth from cosmic rays and makes life on our planet possible. This means that life on Mars cannot exist in the same form and variety as on Earth.
After the “Mariner” exploration of the planet was engaged in the apparatus “Viking” – the rover sent to Earth the first color photos of the surface of Mars, made at the site of landing. In these photos, researchers have noticed traces of soil erosion, which resembled the beds of dried up rivers. Soil analysis showed high chemical activity in the soil, but it was not possible to find traces of any organisms. Negative results were also obtained by testing for organic compounds.
The Phoenix Rover, which landed near the polar caps of Mars in 2008, found traces of perchlorate (chloric acid salt – “Hajtek”), an organic substance that excludes the presence of life in the region, near the landing site. However, the device detected water ice at the pole and thus proved the existence of water on Mars. In addition, it has been established that the soil salinity level is theoretically suitable for life.
NASA’s Curiosity rover, which landed on Mars in 2012 and has since collected data on the climate and geology of the planet, has been even more successful. First, the device found in the rock organic molecules aged about 3.5 billion years – so far, this is the main evidence of the possible presence of life on Mars in the past. Then – a surprisingly complex rock for the planet, which consists of several dozen sedimentary layers. This discovery points to a dynamic environment on Mars in the past – scientists believe that the sedimentary rock was formed by wind and water.
Finally, the SAM gas analyzer installed on the rover has detected a sharp seasonal increase in the concentration of organic oxygen in the Gayle crater, where it is conducting research. In winter and autumn, this figure is 0.16% and increases by 30% in spring and summer. This means that there is not only water on Mars, but also oxygen, although not enough to breathe.
In addition to studying the surface of Mars, scientists have conducted a number of experiments and simulated the planet’s climate in a laboratory environment. In particular, biologists from the German Aerospace Center (DLR) have placed lichens and green algae from Antarctica collected at a height of 3.5 thousand meters in a Martian-like atmosphere. In other words, it contained 95% carbon dioxide, about 4% nitrogen and argon, and less than 1% oxygen and water vapor. Within 34 days the plants not only did not die, but also retained their ability to photosynthesize. The experiment has shown that there can be life on Mars – but so far no trace of it has been found.
What is the essence of the new mission?
After several attempts to study the Martian soil in the environment of origin, scientists decided to bring it to Earth and explore it in the laboratory. This is the main task of the mission of Daring Mars – to collect soil samples, send them to Earth’s orbit, and then deliver them to the laboratory, without contaminating the earth’s organisms.
So far, researchers have had access to only two ways to study the Martian soil – with the help of rovers, whose activities are limited by the level of battery power, the amount of data that can store and transmit robots, as well as the need to make scientific instruments miniaturized, giving up some of their capabilities.
Another option is to study the Martian meteorites that fall to Earth. In this case, scientists are faced with the possible contamination of rock by terrestrial organisms and its sintering as a result of re-entry into the atmosphere. In addition, it was not possible to determine how the rock came to be on Mars – whether it was formed on the planet or whether it represented fragments of objects from the asteroid belt that visited the Red Planet.
The third way is to deliver samples of Martian soil to Earth. This is the most correct way to thoroughly study the rock with the help of the most modern scientific tools. However, it involves many challenges – the mission of Daring Mars can fail at any time.
The plan for NASA and ESA is as follows: in the first stage, the Mars 2020 rover will land in the Jezero crater and collect approximately 500 grams of Martian soil samples from different locations into special metal tubes. Then the containers will be sealed and left in a special place on the surface of the planet.
The Mars 2020 mission should be launched in July 2020. It is supposed that the descent module with Mars rovers will land on the planet in February 2021. It will include two rovers, the probable landing site of which will be the Sirte Plateau and the crater Jezero, located 28 km from each other.
The research apparatuses will have to take soil samples in the vicinity of the landing sites to determine whether there were any living conditions for germs on Mars.
After that, Mars 2020 will continue its mission, and the rover ESA Sample Fetch Rover will come into play. The device will reach the storage point of containers with soil, fold them into a common container the size of a soccer ball and deliver them to the launch point. Then, a rocket developed by NASA will put the container into Mars orbit, where it will be intercepted by the unmanned Earth-return orbiter (ERO).
Then the vehicle will go to Earth – when it reaches near-Earth orbit, the container with samples will be dropped in a special capsule, which will have to use parachutes to land in the desert of Utah.
What are the chances of a mission?
The mission to deliver samples of Martian soil to Earth will be one of the most difficult in the history of space exploration with the help of man-made vehicles. Difficulties can arise at every stage – from the probable unsuccessful landing of the Mars 2020 rover or ESA vehicles, to a series of very complex maneuvers in orbit of the planet, in which the ERO will need to catch a container with soil the size of a soccer ball.
Even if the container can be successfully delivered to Earth, it may break on landing – in which case the Martian soil is mixed with the earth and its study will be almost meaningless.
In addition, there is very little chance that life on Mars still exists today – in this case, in an accident of the container to the Earth potentially can get pathogenic bacteria or other organisms. However, scientists believe that this is an unlikely scenario – the samples will be sealed in several containers, which are planned to open only in a laboratory with a fourth level of biosafety.
However, the contribution to science from the possible success of the mission is worth the risk, said The Guardian Lewis Dartnell, an astrobiologist at Westminster University. “The mission involves an incredibly complex sequence of maneuvers, and there are many stages in which something could go wrong. However, if we want to find evidence that there was once life on Mars, that’s what we need to do. It will be worth the effort.
The mission, according to preliminary estimates, will cost several billion pounds sterling – the exact amount is unknown. In addition, ESA has not yet definitively confirmed its participation in missions. The members of the association should make a decision by the end of November, but the mission description has already been published on the agency’s website.
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