Many different sciences have produced substantial evidence for life on Mars. Many topics are the subject of fierce scientific debate, but the sheer range of evidence of life is almost staggering. There is geological, atmospheric, and even physical evidence that life is indeed abundant on Mars in primitive form. The opposition of the fact life exists on Mars is quickly becoming scarcer, and many theories exist to disprove phenomenon that is happening on Mars right now that is conducive to microbial life. However, there are is so much intriguing evidence that life exists, no one theory can successfully link all the evidence supporting the existence of life on Mars and explain it.
The best piece of physical evidence we have is ALH84001. This cryptic code is actually the name of a Martian meteorite found in the Allen Hills region of Antarctica. It was discovered in 1984, and viewed more as a curiosity than anything else until in 1996 researchers found signs of life. There are several important pieces of information that lead researchers to believe in these signs of life. (Nichols, 2002).
One piece of intriguing evidence in ALH84001 is polycyclic aromatic hydrocarbons (PAH). These are complex organic molecules that are frequently found in meteorites. It is presumed that these molecules were formed through some sort of non-biological process. However, when we look at the PAH in ALH84001, we see that the mixture is quite different than other meteorites, suggesting biological origin (Jones, 2002).
Another piece of this fascinating evidence is mineral deposits. In the core of ALH84001, globules of carbonate minerals, approximately 50 micrometers across, with cores containing manganese and rings of iron carbonate and iron sulfide, have been found. Mineral deposits of this composition on Earth are made by primitive bacteria. A deposit containing such diversity in such a small area makes a non-biological origin highly unlikely (Jones, 2002).
One of the most compelling findings in ALH84001 is, through the use of a powerful electron microscope, the existence of what is being called “ovoid”. These small shapes may actually be fossil remnants of an ancient primitive microbial life form. These fossils are significantly smaller in size than bacteria microfossils found on Earth, yet larger than alleged “nanofossils” discovered recently in terrestrial rocks. These “nanofossils” are generally not considered a viable fossil organism, hence the reluctance to declare the shapes cosmic fossils (Jones, 2002). Current theories are unable to prove these “ovoids” are of a non-biological origin.
These compelling findings are very intriguing, but to make the case for life on Mars, more evidence needs to be presented to convince the most skeptical. Geology is another major factor is considering the case for life on Mars. The presence of water on Mars has been a major facet for scientists determining the likelihood of life on Mars, and fortunately for researchers there has been no shortage of evidence of Mars’ once soggy past.
Strange formations mark Mars’ surface. On Earth formations such as this are only caused by erosion; water rubbing against stone. Photographs of Mars’ landscape reveal what, even to the average person, appear to be dry riverbeds, ancient seafloors, and gorges much vaster than the Grand Canyon. The question, however, is did water cause these curious geological formations. Researchers have been quick to point out that wind and volcanic activity are able to cause many of these features (Kruger 2004).
The debate was fierce, and both points of views had credible evidence to back them up. It was not until early in 2004 one of the Mars rovers completed chemical testing on a large outcropping in the Meridiani Planum. The surface of the formation is called a parallel lamination, and this formation is caused by minerals setting out of water. The formation was also rutted with vugs, tiny cavities created when salt crystals associated with briny water dissolve. Spectrometer tests confirmed that the wall was rich in sulfates, and contained a mineral called jarosite, which forms in water, but even contains water as well (Kruger 2004). There is no other scientific explanation than this area was once covered in water and NASA is confident enough to say that Mars’ past was a wet one.
In addition to indisputable evidence that the Meridiani Planum was covered in water, more intriguing is the “blueberries” on Mars. This term refers to spherules scattered through the rocks. These spherules are caused by minerals accreting through water, although, in certain cases, volcanic activity can cause them. However, the pattern in which they are dispersed, scattered randomly; not layered on top of rock, makes it virtually impossible for volcanic activity to have caused this phenomenon (Kruger 2004). Lead investigator of the rover missions, Steve Squyres, sums it up nicely by saying, “We have concluded that the rocks here were soaked with liquid water. The ground would have been suitable for life” (Kruger 2004).
So the evidence is there that life once existed on Mars. Life on Mars today is probably much different. The landscape is barren, rocky, and cold. Life would be hard, even for a microbe. Can a primitive life form exist in such a condition? Life is very resilient, and studies prove that microbes can exist in extreme circumstances.
Studies prove that in extreme soil conditions, microbes can survive. Talus soils on Earth have been used to model the severe conditions on Mars. Current methods dictate Mars’ could actually be abundant in life below the surface (Ley, Williams, Schmidt 2003). On Mars, according to experiments on Earth in extreme environments, it is even possible that dormant organisms on the surface exist in polar ice caps and become active during periods of high obliquity (defined as the period of time when the axis is tilted towards the sun, which occurs approximately ever 10E8 years) (Ley, Williams, Schmidt 2003). During this time period, temperatures are high enough to allow liquid water to exist on the surface in regolith, or the loose heterogeneous mixture, covering rock (Ley, Williams, Schmidt 2003). So, in experiments meant to model the extreme conditions on Mars, it has been proven Mars would provide a viable habitat for microbes below the surface, and evidence exists that microbes may even have a hostile, but livable, habitat on the surface.
Geology and microbiology presents, to a great extent, irrefutable evidence, but studies of the present and past atmosphere of Mars add yet another intriguing argument. Trace gases in ALH840001 suggest that the Martian atmosphere was much denser, and much more hospitable to life as we understand it in the past. There is little argument amongst researchers that Mars’ atmosphere is quite different than it used to be.
The presence of methane gas has also been found in the atmosphere of Mars by three independent teams (Hogan, 2005). Typically, many researchers dismiss this gas, a gas known to be created by bacteria, as some sort of non-biological process, such as an ancient comet collision or volcanic activity. However, the methane is found localized, not distributed evenly throughout the atmosphere. Methane takes hundreds of years to break down by itself, giving wind the opportunity to disperse it throughout the atmosphere. Since methane takes such a short amount of time to break down, compared to other gases, the methane in the atmosphere must be somewhat recent, and the fact it is not deteriorating means that it must be replenished. An instrument called the Planetary Fourier Spectrometer (PFS) has detected formaldehyde, in concentrations of 130 parts per billion, in Mars’ atmosphere (Hogan, 2005). The presence of formaldehyde is a very significant finding, mainly because this gas is produced by the oxidation of methane. The presence of formaldehyde also helps explain why the distribution of methane is localized and not evenly dispersed; if bacteria created the methane, it would be localized to the region they lived in. The only logical assumption, drawn by leading Mars researcher Vittorio Formisano is that, “…until it is shown that non-biological processes can produce this methane, possibly the only way is life.”
The measurement of methane is highly debated and Formisano’s colleagues fiercely question his methods, such as the ability of the PFS to successfully detect formaldehyde, our inability to accurately model the internal geology of Mars, and other such questions. However, to put the probability of life on Mars into perspective, there is no non-biological phenomenon known today that can produce methane in the patterns observed in Mars. If it is indeed a non-biological process, it is, as of today, unknown.
The combination of all of this evidence conclusively point to the existence of life on Mars, presumably underground in aquifers, whose existence is proven probable by current geological and atmospheric studies. The age of thinking little green men may inhabit the red planet is gone, but the fact life exists outside this solar system in any shape or form puts our own existence into perspective. When the announcement is made that the “smoking gun”, most likely a live microbial Martian specimen, is found, do not be shocked. The news has been a long time coming, because the evidence has been piling up in abundance since the discovery of potential microfossils and mineral deposits in ALH840001 and even more so since the Spirit and Opportunity rovers touched down and observed the once-wet landscape of the red planet.
References
Kruger, J. (2004, March). The blueberries of Mars. Time, 163(11). Retrieved December 8, 2005 from EBSCOhost database.
Hogan, J. (2005, February). A whiff of life on the Red Planet. New Scientist, 185(2487), p6-7. Retrieved December 7, 2005 from EBSCOhost database.
Ley, R., Williams, M., & Schmidt, S. (2003, April). Microbial population dynamics in an extreme environment: controlling factors in talus soils at 3750 m in the Colorado Rocky Mountains,
Biogeochemistry, 68, p313-335. Retrieved 12/12/2005 from EBSCOhost database.
Jones, N. (2002) Ancient time capsule reveals Martian past. New Scientist, 175(2358), 20. Retrieved December 6, 2005, from EBSCOhost database.
Nichols, M. (2001) Signs of nearby life. Maclean’s, 114(11), 50. Retrieved December 6, 2005, from EBSCOhost database.
The idea behind the whole concept is simple: even though the camera is handicapped with a focal plane of around f/10, the removal of the shutter mechanism allows for long-exposure photography. All the original pictures taken by me on this site are taken at f/2.8, and more often than not are a 30-second exposure. However, for the budget-minded astrophotographer, we are simply replacing the poor focal length with more time to collect light. A 25-minute exposure will generally, under decent conditions, provide a photo yielding about 2.5 more stars than are visible. Not too shabby, especially since disposable camera bodies are free from most photo labs. You also will want to pick up some used film canisters with toothed spindles.
