Where Should Search Traces of Life, Which Could Appear on Mars in the First 300 Million Years

Fourth Conference on Early Mars 2017 (LPI Contrib. No. 2014) 3005.pdf

WHERE SHOULD SEARCH TRACES OF LIFE, WHICH COULD APPEAR ON MARS IN THE FIRST 300 MILLION YEARS. A. P. Vidmachenko, Main astronomical observatory of NAS of Ukraine, Str. Ak. Zabo- lotnoho, 27, Kyiv, 03143. [email protected].

Mars rovers and orbital modules received a huge by the fall of fragments of a very large asteroid [22, 23]. amount of information about Mars. The data collected In this case, the location of the surface details and even by them allowed to reconstruct possible stages of the the shape of Mars could quickly and strongly change. development of events on the planet [14, 16, 23]. About Before that, ice caps lay on the poles, the planet was 4.5 billion years ago, the first geological era, the Phyl- enveloped by a dense gas atmosphere, and the water locian, began. It lasted ~ 500-700 million years. It is filled the lakes and seas. It is assumed that the atmos- believed that Mars was then a humid planet. In this phere and water were lost after such a powerful one- case, proceed from the fact, that the minerals belonging shot bombardment. Existing impact craters, and a large to this era subjected to significant water erosion. These amount of magnetic sand (maghemite) on the surface rocks contain clay minerals – phyllosilicates. To form indicate a possible bombardment. It is formed only them, a lot of water, the temperature is above 273 K during oxidation of magnetite with simultaneous strong and low acidity is needed [18]. But such a wet period heating. in the history of the planet was very short for so that (A similar substance occurs only on the territory of the possibility of development of the modern terrestrial Yakutia on the Earth. It is believed that 35 million type of life [13, 21]. In its early years, Mars was like years ago, fragments of an asteroid 8-10 km in diameter the ancient Earth. And the conditions on the planet fell there [11, 22]). were the same as on the then Earth. It had a dense at- Emissions of millions of tons of soil on thousands mosphere with a pressure of 0.4 bar, a water ocean on of kilometers, covered a significant part of the surface the surface, and there was much warmer than it is now. of Mars. In the same place, the forms of life that began That is, the planet was once much more suitable for the to form could be hidden. Now in many places on the existence of life than it is today. It was in those years surface of the planet thousands of sites with scattered that simple forms of life arose on the Earth. So, in are contained in a young volcanic soil. After the global Canada traces of vital activity of the most ancient bac- climate change, probably caused by volcanic activity teria on the Earth are found. They show that life on after the fall of a large asteroid, a new era – Theiikian – Earth existed almost 4.3 billion years ago; only 200 began. It lasted from 4 to 3.5 (3.3) billion years ago million years after the formation of the earth's crust. It [12, 15, 17, 19]. Then, due to powerful volcanic emis- is possible that the same could happen on Mars. So, sions, a large amount of sulfur was supplied to the at- recently on Mars, traces of methane and formaldehyde mosphere, the environment became very acidic, and were detected. They can talk about a possible proof of water reacted with sulfur compounds and formed sul- the presence of life on the planet [6, 9]. The embryos of phates. Evidence of this is the presence of gypsum and a possible life on the surface of the planet could have gray hematite in rocks belonging to the corresponding been brought down by fragments of comet nuclei age. And the situation began to change. The planet be- (panspermia) [1-3, 24]. Somewhat later, the collision of gan to cool slowly; The activity of volcanoes decreased the planet with planetesimals could lead to the for- and the release of gases into the atmosphere decreased. mation of huge impact craters. As a result of such pro- About 3.3-3.5 billion years ago, the third Siderikan era cesses, the newly formed life could be conserved under began. It was at this time that a large-scale formation of powerful soil emissions [11, 17, 19]. Evidence of im- non-hydratable iron oxides began, which could give the pacts of large bodies of Mars is the Hellas Planitia, planet a reddish color [20]. Now Mars is geologically located near the southern polar region. Now it is a plain almost dead [21, 23]. Mars has virtually no magneto- with a diameter of more than 4000 km. At the bottom it sphere and there is a very subtle atmosphere. This is narrows to 1500 km, and is surrounded by rock out- clearly not enough to protect a possible life from bom- bursts. Its depth in some places reaches 9 km. Five gi- bardment by solar wind and hard ultraviolet (UV). But ant craters Argyr, Hellas, Isis, Tavmasia and Utopia lie there is a chance, that if life on Mars once appeared, it on an arc of a great circle. did not disappear without a trace. It could move from The close age and peculiarities of their mutual ar- the surface of the planet to its interior, can be stored rangement suggest that these craters could have formed there either in fossils, and possibly in some simple simultaneously, as a result of a single cataclysm caused forms. Therefore, it tracks should be sought at a depth Fourth Conference on Early Mars 2017 (LPI Contrib. No. 2014) 3005.pdf

below the soil. But what kinds of life forms can there (2013) 8Meteoroids-2013. 077. [4] De Maayer P. et al. be conserved, and/or survive? (2014). EMBO Repots. 15(5), 508-517. [5] Hecht If life on Mars today there is, then, certainly, it is M.H. et al. (2009) Science. 325(5936), 64-67. [6] microbial. But even in this – we are not sure until we Krasnopolsky V.A. et al. (2004) Icarus. 72(2), 537-547. find and study them. However, we can make some as- [7] Ojha L. et al. (2015) Nature Geoscience. 8(11), sumptions about the nature of Martian life. For this, it 829-832. [8] Parro V. et al. (2011) Astrobiology. is necessary to investigate some special biological as- 11(10), 969-996. [9] Peplow M. (2005) Nature. pects on Earth. The convincing evidence that liquid 436(7048), 158-159. [10] Polyextremophiles: (2013) water periodically flows on the surface of Mars is the Ed. by J. Seckbach et al., Springer. 27, -481. [11] spectroscopic detection of hydrated perchlorate salt in Schultz P.H., et al. (2014) Geology. 42(6), 515-518. streams on the walls of Martian craters. Perchlorate [12] Vidmachenko A.P. (2016) 5Int.Sc.Conf. Ed. by A. salts are composed of chlorine and oxygen, which are Mozhovyi, 43-48. [13] Vidmachenko A.P. (2012) associated with various other elements. Some perchlo- AstSR. 8(2),136-148. [14] Vidmachenko A.P. (2009) rates do not allow freezing of the liquid at temperatures AstSR. 6(1-2), 27-43. [15] Vidmachenko A.P. (2016) below -70 ° C. The most famous saline basin on Earth 18YSConf., 16-17. [16] Vidmachenko A.P. (2009) with calcium chloride is Don Juan Pond in Antarctica. AstSR. 6(2), 131-137. [17] Vidmachenko A.P. (2016) But, perhaps, the Martian salt solution is even more 18YSConf., 14-16. [18] Vidmachenko A.P. (2009) salty. Also, a wide spectrum of halophilic (salt-loving) AsAl. 56, 225-249. [19] Vidmachenko A.P. (2016) and psychrophilic (cold-loving) microbes was found on LPICo1912.2002. [20] Vidmachenko A.P. et al. (1981) the Earth. Recently, found “lovers” of cold salt (psy- SSRes. 14(4), 157-159. [21] Vidmachenko A.P. and chrophalophiles) [5, 10]. They live in salt Antarctic Morozhenko A.V. (2012) AsAl. 59, 221-243. [22] lakes, or in veined glacial ice. The temperature limit for Vidmachenko A.P. and Morozhenko O.V. (2014) cell division is -12ºC, and for maintenance of the basic pcse.book MAO, NULES, -388. [23] Vidmachenko metabolic functions is -20ºC. Some of the microbes A.P. and Morozhenko O.V. (2014) AstSR. 10(1), 6-19. even produce antifreeze proteins that help limit the [24] Vidmachenko A.P. and Steklov A.F. (2013) growth of ice crystals in their cells. Adaptations of psy- AstSR. 9(2), 146-148. chrophalophiles on the Earth hint at possible life strat- egies of Martian microbes. But there are a few more problems that have to be overcome by any form of life on Mars. First, Mars is devoid of the ozone layer, and all day its surface is sterilized by UV radiation. One way to avoid radiation is to live under the surface. Usu- ally perchlorates are highly toxic compounds for most organisms on Earth [5, 7]. But in one of the driest and most exposed to the radiation of the Atacama Desert on Earth, microbes are found that live in thin films of liquid water on the surface of salt crystals [7, 8]. That is, life on Earth repeatedly demonstrated an amazing abil- ity to adapt to toxic environments. There are microbes that live in acid mines and in lakes with arsenic. Regis- tered arctic microbes that have adapted to high levels of mercury contamination. In addition, on Earth, there are bacterial enzymes that can destroy perchlorate. A prom- ising habitat is the thin water films that the polar landing gear "Mars Phoenix" observed in the soil on its own landing area. The proof of the presence of liquid water on Mars does not mean that there is life on Mars. But this gives some hope. References: [1] Churyumov K.I. et al. (2014) book:CAMMAC. 98-108. [2] Churyumov K.I. et al. (2014) AstSR, 10(1), 37-42. [3] Churyumov K.I. et al.