Astronomy....The Subject Life Mars: Past / Present?

¶ … Astronomy....The subject "Life Mars: Past / Present? It 11 pages length. I attach an outline Final project paper instructions final project. I stress I NEED AN EXCELLENT RESEARCHER/WRITER FOR THIS PLEASE.

The existence of life on Mars has been a topic that has continuously fascinated mankind. Mars is the planet that is closest to Earth and the only planet in the Solar System where the hypothesis of existence of life can actually be debated. All the other planets are much too hot or cold for life to be even discussed. As a consequence, a lot of research about Mars has been directed towards identifying potential traces of life, in the present or from the past, as well as analyzing the existing conditions that could make the planet habitable.

From the introductory part of this paper, there needs to be a clear understanding about the fact that life on Mars does not exist at the present, nor is there evidence that life on Mars existed at some time in the past (Conrad et al., 2013). The entire research process is currently directed towards two dimensions, with distinct correlations between them.

The first dimension refers to analyzing elements that could potentially make Mars a habitable planet. These include elements such as water or the chemical environment. An important part of the research has been focused on analyzing whether such elements existed in the past, which could be a potential argument in favor of life having existed in the past as well.

Another dimension involves searching for microorganisms that would be a clear sign of the existence of life on Mars. As shown previously, there have been no clear development and no concrete evidence in this sense so far. Because of these two dimensions, Mars is also an interesting study in terms of the origins of life. Scientists believe that conditions were similar on Earth 3.5 billion years ago, when the first signs of life appeared on Earth. As such, studying the environment and evolution on Mars could provide relevant information about how life started on Earth (McKay, 1989), answering some of the existing dilemmas.

Literature Review

Section Introduction

This literature review section will focus on the two dimensions identified in the introduction, namely on studies that analyze the existing environment on Mars, aiming to draw conclusions related to the potential habitable conditions, the other to studies that have looked into the actual existence of microorganisms and other living entities on Mars.

Review

According to Beaty D. And a group of researchers (2006), there are four large categories of factors that are used in determining habitability. These include water, the chemical environment, presence and nature of energy (for metabolism purposes) and physical conditions. Beaty develops each of these categories into subsequent elements, of which some of the most relevant ones include salinity, pH, liquid water activity (for water), nutrients and presence of toxins (chemical environment), solar and geochemical forms of energy and elements such as temperature, pressure, radiation and climate for the last category.

Other researchers have focused on past periods of time, namely on whether factors that would have led to the creation of a habitable environment existed some time in the past. This current was encouraged by the results that the NASA Curiosity Rover brought in 2013. Its analysis of rocks on the surface of Mars concluded that there may have been conditions in the past to support living organisms such as microbes (Brown, 2013). The scientists analyzed the rock sample provided by the Rover and identified several chemical elements that are essential for life, including oxygen, carbon or hydrogen.

A long discussion has been opened as to whether there is water on Mars. There are several aspects to this topic, but all scientists agree on the fact that water cannot exist in its liquid form, in the present day, on Mars. The discussions are thus focused on (1) whether water exists in solid or gas forms and (2) whether water existed, in any form, some time in the past on Martian surface.

Although water does not appear in actual form on the surface, there are particular exceptions, such as water particles formed temporarily around dust particles (Shiga, 2007). As Shiga has shown, the problem with liquid water is either that the temperature falls below freezing levels or that, when this does not happen, such as in the areas around the equator, where temperatures are occasionally above freezing levels, the low atmospheric pressure leads to a quick evaporation.

There is more evidence for water ice, either at the Poles or below the surface at other latitudes (Feldman, 2004), apparently abundant. There has been some concrete evidence from exploratory missions that ice may also exist in what appears to be a crate. Other large patches of ice are locating even around the Equator. There are also glaciers present on the Martian surface.

Jakosky and Haberle (1992) have dedicated their research to the presence of water vapors in the atmosphere on Mars. Further work on water vapors in the atmosphere on Mars comes from Titov et al. (2012) mention the observations of the Imager for Mars Pathfinder (IMP), while Sanders (2011) looks into the findings of the ESA Mars Express spacecraft.

According to the latter findings, water vapors are formed as ice from the Martian poles melts and is released as vapor into the atmosphere. The combination of these water vapors and dust molecules creates cloud. However, when there is not enough dust for this to happen, the water vapors remain in a supersaturated state.

A lot of new potential for research was opened when Mariner 9 revealed, in 1971, the existence of what seemed to be valleys of rivers that formerly existed on the planet. Other forms of flowing water, including streams, led to the idea that there may have existed previously a potential for a similar type of circuit of water in nature as there is on Earth (Raeburn, 1998). Di Achille and Hynek also referred to an "Earth-like hydrologic cycle" (Di Achille, Hynek, 2010).

An article in Science Daily, published based on materials from the University of Colorado at Boulder proposed the idea that an ancient ocean may have covered as much as a third of the entire surface of the planet. The scientists analyzed the information and data regarding a series of river delta deposits and their conclusion was that as much as 29 out of a total of 52 river delta deposits may have been associated, in some way or other, to such a large Martian ocean.

This hypothesis is in no way unchallenged in the scientific community. Among many others, Carr and Head (2003) suggest that what appear as being shorelines are not. Among the potential alternatives, scientists refer to the fact that the basins may, in fact, be caused by a meteor impact or anything of significant force that would have shifted the ground in a manner that would have created a large crater.

Cabrol and Grin (2010) have looked at the existence of several lake basins on Mars. They appear to mirror what is now on Earth, including the fact that some of the river valleys are leading up to them, suggesting that, in the past, rivers flowed into the lakes. There is extensive research on the nature of these lakes, particularly on how water accumulated there.

Different schools of thought propose either the fact that they were supplied from the atmosphere, while others suggest that they were supplied from the underground. This all leads back to the theory of the existence of a natural cycle of water on Mars, similar to the one on Earth, although likely in a different form.

Di Achille and Hynek's article is also useful because of their investigation into lake deltas, an important sign of a sustained, over a longer period of time, presence of water on Mars. Di Achille and Hynek support the idea that deltas take longer to form, so their existence implies a continued water presence in a particular region.

When looking for signs of life on Mars, some researchers have focused on a wider perspective of things, namely on the potential existence of intelligent life in the Universe. Basalla (2005) has written a history of what he terms as speculation about the existence of intelligent life in the Universe, going from Plutarch to the present time. Because this work is so vast, it is useful for a study about life on Mars, giving several perspectives as to what this implies.

When man speculates about life on other planets, Mars included, he also speculates about what form this life takes: is it humanoid form? Is it different, are there different societal and group organizations etc. With Basalla's work, one does not necessarily have the answers to these questions, but a better idea about how this research continued over time, with different ideas and opinions.

Studies argue that if life forms exist on Mars, the low temperature and the ionizing radiation would only allow these forms of life to exist under the surface and in a dormant form (Lovett, 2007). Dartnell and others believe that bacteria living under the surface would have problems regenerating and would have a limited lifespan.

They suggest that frozen crater lakes could provide better living conditions and survival chances for such living entities. However, as Delory pointed out, one of the elements of the theory of evolution proposes the idea that living organisms have evolved by adapting to their environment, improving their organisms to resists harsh conditions.

The legitimate question regarding life on Mars can thus be whether organisms could have perhaps adapted to the Martian environment, either in the present or in the past. This would have meant that organisms could have developed to withstand the ionized radiation and to exist even at very low temperatures. There is still considerable debate around this topic, since embracing this paradigm could virtually change entirely the evaluation and discussion about life on Mars.

Some studies have focused on correlating the presence of water with the existence of living forms. An important fact to mention, as shown previously, is that life needs liquid water, but there are additional factors that are required to make an environment habitable. Another important distinction is the fact that the past existence of habitable conditions on Mars does not confirm the fact that life did indeed exist on Mars at some time in the past. So, the theory (disputed, as previously discussed) that liquid water existed on Mars does not ensure the fact that life also existed on Mars.

Research has often moved beyond identifying living organisms and towards searching for what would be life traces, biosignatures as they are called. These include the presence of methane or of formaldehydes. As Mumma (2003) showed, methane was discovered in 2003 and it is believed that there is a permanent and constant supply of methane, showing that it is produced in some manner on Mars. The presence of methane would allow for the development of bacteria living on methane.

There is a continuous discussion on the nature of methane production on Mars, ranging from methane resulting from organic compounds on meteorites, converted to methane with the help of ultraviolet radiation (Keppler et al., 2012) to methane being produced on the surface as a result of geological interactions, although there seem to be too many adverse conditions for this to occur.

There are also researchers who believe that there is no significant methane production process on Mars and that any presence of methane on Mars is infrequent, leading to the conclusion that it does not reflect a continuous production action (Zahnle, 2011). This would mean that there are in fact no bacteria or microorganisms producing methane.

Section Summary

Literature on the subject of Life on Mars is significant. There have been a lot of studies and research on this topic, particularly as more concrete elements are communicated by several exploratory missions on and around the planet. This section has been focused both on studies examining the presence of elements that could lead to a habitable environment on Mars and on studies that look as to whether there are signs of life on Mars. There seem to be more studies on the former topic rather than on whether there are signs of life on Mars.

The literature review has focused, first of all, on articles and studies that examine whether water on Mars exists or existed some time in the past. For the present, the literature looks into the presence of water as ice at the two poles, as well as water vapors in the atmosphere. In terms of the past, there is a continuous controversy as to whether one can identify former lake and river basins and valleys or whether these are actually a result of some other physical action, such as an earthquake or a meteorite impact or other geological feat.

In terms of the present existence of life on Mars, studies generally concur on the idea that if life exists, it is likely in the form of microbes, bacteria or similar entities. Two factors seem to impede to the existence of life on the Martian surface: radiation and very low temperature. As such, recommendations are to look for life forms either under the surface or in frozen ice formations.

A distinct category of researchers proposes the idea that life on Mars could have adapted or could adapt in the future to these harsh conditions, in a similar manner that life on Earth evolved. It remains to be seen whether this evolution can take place in the absence of some of the factors that make an environment habitable in the first place.

Conclusion

Review of Key Facts

This paper started with the strong assertion that life on Mars does not exist. In the conclusion part of this paper, this statement can be nuanced to say that it is not believed that life on Mars exists in the present or that it has existed in the past, but that researchers are conducting investigations in different areas to better understand whether this conclusion is correct and whether there is a possibility that life will exist in the future.

As the paper has shown, there are several directions to research of life on Mars and this research is also backed by the evidence that the different missions to Mars have brought. The research his also focused on different temporal dimensions: past, present and future. In each of these temporal phases, the researchers aim to analyze whether life exists and whether the environmental conditions make that possible.