Life on Mars
Introduction
While observing Mars during the planet’s “Great Opposition” in 1877, Italian astronomer Giovanni Schiaparelli saw dark lines crisscrossing the surface of the planet. He reported seeing “canli,” the Italian word for channels (AMNH). This finding was misleadingly translated into English as “canals” – a word that has a certain “suggestion of intelligent design,” according to astronomer Carl Sagan (Cosmos). This event triggered a worldwide fascination with the Red Planet and speculation on what life may exist there.
At the turn of the 20th Century, H.G. Wells portrayed a violent race of advanced Martians regarding the Earth with envious eyes and leaving their dying world to conquer ours with their great machines. Around the same time, Edgar Rice Burroughs wrote of John Carter, a gentleman from Virginia who traveled to “Barsoom,” the native’s name for Mars – a dying planet divided by two warring races: the red humanoids of Helium and the green, four-armed giants known as the Tharks.
The Martians of 1950s b-sci-fi films became even more outlandish. Creatures like the stocky, brown, three-eyed invaders in the 1953 adaptation of The War of the Worlds or the giant “bat-rat-spider-crab” from 1959’s The Angry Red Planet scurried across the blood-red soils of a fictional Mars. Though excitement for this alien world was building, our first glimpses of this mysterious neighbor, in the decades to come, would be somewhat anti-climactic.
The Mariner 3 spacecraft gave humans the first close-up look at Mars during a flyby in 1964. The Viking landers sent back the first pictures from the surface of another planet in 1976. These images showed a world that seemed almost familiar. The vast rocky planes and crooked mountain peaks closely resembled Earth deserts. If not for the rust-colored soil, Mars may not have seemed alien at all. Undoubtedly many people were disappointed that our probes did not capture a little green man waving back at the camera. But, even with those first missions, evidence began to mount for the presence of small, but certainly not insignificant, Martian life.
Recent evidence nearly conclusively proves that Mars was once a much warmer and wetter planet. Conditions on Mars could have been very conducive to life several billion years ago. Unlike Earth, however, Mars failed to maintain an atmosphere and the liquid water evaporated into space and the planet became increasingly arid and vulnerable to high levels of radiation. If life existed before this climate change, could it have evolved fast enough to survive? Even with the planet’s extreme conditions, could there be small oases capable of supporting microbial life? It wouldn’t take a six-foot, bug-eyed beast with eight tentacles to profoundly alter our views of the universe – all we need is just one microscopic cell.
2. Notable Mars Missions
Viking 1 and 2 — Reached Martian surface on July 20, 1976 and September 1976, respectively. These landers were designed to analyze the Martian soil, atmosphere composition, weather and geographic features. Biological experiments found cryptic evidence of chemical activity in the soil but could not link that to the presence of life (NASA JPL). However, recent evidence suggests that these may have been low levels of organic compounds that the experiments were not sensitive enough to analyze (Handwerk 2006).
Mars Global Surveyor — Reached Mars orbit on September 12, 1997 and was operational through 2006. This orbiter was designed for extensive mapping of Mars and the study of daily weather patterns. It recorded images of gullies, debris flows and other evidence of surface water in Mars’ distant past as well as CO2 ice, which is slowly receding at the poles (NASA JPL).
Mars Pathfinder — The first successful lander since the Viking program, the rover Sojourner was designed to analyze the geological history of Mars, determine soil composition and look for signs of life. The landing site was selected because scientists believed that the area had once been the subjected to a large flood. The mission provided evidence suggesting that Mars had a warmer and wetter climate in the past (NASA JPL).
Phoenix — The lander descended to the Martian Polar region under its own power on May 25, 2008. Instruments detected chloride, bicarbonate, magnesium, sodium potassium, calcium, and traces of sulfate in the soil. The most important discovery was the presence of Perchlorate, a strong oxidizer in the soil that could contribute to biological metabolism as an energy source for anaerobic reduction and through its hygroscopic properties. This chemical could also be used for rocket fuel or as a source of oxygen for future manned missions (NASA JPL).
Mars Odyssey — The orbiter arrived at Mars on October 24, 2001 and conducted a planet-wide geological survey mission. It successfully mapped out mineral deposits across the planet and identified areas of water-ice just below the surface. The probe also determined that radiation in low-Mars orbit is twice that in low-Earth orbit (NASA JPL).
Spirit and Opportunity Rovers — After landing on Mars on June 10, 2003 and January 24, 2004, respectively, these rovers began long distance and long duration exploration of the planet. They were far more mobile than previous rovers and contained tools to examine the interiors of rocks. Opportunity discovered a dry lakebed and found many sulfate deposits in the sedimentary bedrock. Spirit examined a basaltic region, shaped greatly by volcanic activity. (NASA JPL).
Mars Express — This probe, which reached Mars in 2004, consists of an orbiter and a lander, both designed to look for evidence of water beneath the surface and examine evaporite deposits. The orbiter discovered that 15% of South Pole ice is water and the rest is CO2. Analysis of the atmosphere showed a continually renewed concentration of methane. The source of this gas is unclear but, since it disappears quickly from the air (possibly due to hydrogen-peroxide in the soil (Gough et al. 2011)), it must be replenished regularly. Methane-producing microbial life is one possible source (NASA JPL), although it could be the result of natural geologic processes, like iron oxidation (Steigerwald 2009).
Mars Reconnaissance Orbiter — Since March 2006, this orbiter has been taking the most detailed and close-up pictures of Mars ever captured from orbit. The goal is to study the Martian soil and build on NASA’s geographic and sediment maps of the planet. It also contains a new communication system known as “Interplanetary Internet,” which allows for faster and more direct links with Mission Control and with future spacecraft.
Section 2
Include some current research in each topic, with at least one figure showing data.
Section 3
Include some current research in each topic, with at least one figure showing data.
Conclusion
Overall paper length should be 3,000 words, with at least 3 figures.
References
Edited by student of Joan Slonczewski for BIOL 238 Microbiology, 2009, Kenyon College.
