Historical Geology
Spring 2005

Liquid Water on Mars and the Search for Life

Is there life on other planets? For decades this question has been on the minds of scientists and regular people alike. Countries have sent missions to explore space, our moon, and most recently Mars.

Picture 1 Credit to: pusillanimous.squarespace.com/ (This is a dead link I found through google.com. The active link is: http://gw.marketingden.com/planets/images/fullsize/mars.jpg)

In the search for life on other planets, scientists must first find the proper conditions for life as we know it. What are these conditions? The requirements for life include energy (from our sun) and the elements; mainly carbon, hydrogen, and oxygen. From these elements, water, carbon dioxide, and other organic molecules can be formed.

Scientists have already determined the thin Marian atmosphere is composed mostly of carbon dioxide. But because water is a main requirement for life, you can understand astrobiologists’ principal search for it on Mars. These scientists are searching for the presence (in Mars’ past and present) of liquid water. Through several fly-by and ground explorations, researchers have found frozen water at the north and south poles, beneath the soil in the southern hemisphere, and water in the atmosphere.

Picture 2 -Martian Atmosphere Credit to: Spacetech’s Orrery The Solar System in Action http://www.harmsy.freeuk.com/mars.html

Picture 3 Credit to: Leonard David, http://www.space.com/scienceastronomy/solarsystem/odyssey_viking_020528.html

“Soil enriched in hydrogen is indicated by deep blue colors, where a low intensity of so-called epithermal neutrons is found. View is of Mars' south pole.”

Please click on this link to compare Earth’s South Pole to Mars’ North Pole. Credit to NASA’s Sibling Rivalry: A Mars/Earth Comparison by Dr. Jim Garvin, Chief Scientist, NASA Mars Exploration Program.

The water at the Martian poles is frozen beneath layers of dry ice (carbon dioxide). The water beneath the soil is frozen because of the frigid temperatures on Mars. The traces of water found in the thin atmosphere are believed to be the result of methane oxidation. Other evidence of possible liquid water on Mars includes the geologic formations on the planet’s surface. Data gathered from photos show now dry riverbeds, canyons, gullies, lakebeds, seafloors, and shorelines.

Picture 5 Credit to: NASA/JPL/Malin Space Science Systems, http://www2.ifa.hawaii.edu/newsletters/article.cfm?a=138&n=14

Further evidence discovered by NASA’s Mars Global Surveyor is the presence of magnesite, a carbonate formed when CO2 meets other minerals in the presence of water. Mars rover Opportunity also discovered large sulfate salt deposits and deposits of other minerals including jarosite and hematite in Meridiani Planum.

NASA researchers believe that at some time in its past, Mars had a habitable climate and liquid water. This doesn’t mean life existed, but the conditions on Mars were suitable. If there ever was any, most likely life on Mars was microbial life. And if life did exist on Mars, some of it could still be present today.

Although carbonates have been found on Mars, they do not occur in the amounts consistent with the evaporation of an ocean. Yet the evidence of water is clear. So why the low amounts of carbonates? The explanation comes from Alberto Fairen of the Universidad Autonoma de Madrid in Spain. Fairen explains that Earth’s oceans have a pH of 8, which allows carbonates to form during evaporation. If the Martian oceans had a pH below 6, carbonates could not have formed during evaporation.

Fairen and his colleagues studied the mineralogy of Meridiani Planum and compared it to the Tinto River in southwestern Spain. The mineralogies are surprisingly similar! Both jarosite and hematite are common to the two locations, and the Tinto River is highly acidic. This is strong evidence the Martian oceans had an acidic pH as well. Could life still have existed in an acidic Martian ocean? Yes. The acidic Tinto River has a rich biosphere, thus evidence still allows for possible life on Mars.

The water ice at Mars’ poles could harbor life forms similar to microbes found on Earth. Pockets of ice and briny water are home to cyanobacteria, a life form that generates its own sunscreen. Could similar forms of life be found on Mars? In 2002, John Priscu and a team of scientists traveled to Lake Vida in Antarctica. The team discovered 2,800 year old microbes in the frozen waters of the lake and managed to revive them. The microbes were in a state of suspended metabolism, similar to dormancy. Research from Priscu’s team suggests bacteria and the bacteria’s DNA can remain viable up to one million years. This is most likely the type of life we can expect to discover on Mars if life ever existed there.

Picture 6 “A cyanobacterium of the genus recovered from the ice above Lake Vida in the Antarctic.” Taken from: Ancient, Frozen Antarctic Life Revived, Along with Hopes for Life on Mars; http://www.space.com/scienceastronomy/antarctic_life_021216.html

Works Cited And Other Interesting Links

Ancient, Frozen Antarctic Life Revived, Along with Hopes for Life on Mars; Robert Roy Britt, Senior Science Writer; December 16, 2002; http://www.space.com/scienceastronomy/antarctic_life_021216.html

Hopes for life on Mars undermined as probe finds no trace of oceans; Steve Connor, Science Editor; August 22, 2003; http://news.independent.co.uk/world/science_medical/story.jsp?story=436010

Mars Ice is Mostly Water: Good for Biologists, Bad for Terraformers; Robert Roy Britt,
Senior Science Writer; February 13, 2003; http://www.space.com/scienceastronomy/mars_ice_030213.html

Mars Liquid Water Elusive, But Present; Robert Roy Britt, Senior Science Writer; August 21 2003; http://www.space.com/scienceastronomy/mars_liquid_030821.html

Odyssey Discovers Abundant Water Ice on Mars; Robert Roy Britt, Senior Science Writer; March 1, 2002; http://www.space.com/scienceastronomy/solarsystem/odyssey_update_020301.html

Odyssey's Icy Discovery Warms Up Controversial Theories; Leonard David, Senior Space Writer; May 28, 2002; http://www.space.com/scienceastronomy/solarsystem/odyssey_viking_020528.html

Scientists Seek Scent of Life in Methane at Mars; Leonard David, Senior Space Writer;
August 24, 2004; http://www.space.com/scienceastronomy/mars_methane_040824.html

Special: Sibling Rivalry: A Mars/Earth Comparison; Dr. Jim Garvin, Chief Scientist, NASA Mars Exploration Program; April 21, 2004; http://www.nasa.gov/centers/goddard/news/topstory/2004/0422earthmars.html

The Moon Or Mars…Which Shall It Be? Leonard David, Senior Space Writer; January 28, 2002; http://www.space.com/news/moon_or_mars_020128-1.html

The Solar System in Action; Spacetech’s Orrery; http://www.harmsy.freeuk.com/mars.html

UH Astrobiology Team Studies Water and Life in the Universe; Karen Meech and Eric Gaidos; Winter 2004; http://www2.ifa.hawaii.edu/newsletters/article.cfm?a=138&n=14

Water Ice Found Near South Pole of Mars; Robert Roy Britt, Senior Science Writer; December 5, 2002; http://www.space.com/scienceastronomy/solarsystem/mars_ice_021205.html

Water Once Filled Mars Opportunity Rover Landing Site; Tariq Malik, Staff Writer;
March 2, 2004; http://www.space.com/scienceastronomy/opportunity_news_040302.html

Water on Mars; Malcolm Walter; May 11, 2004; http://astronomy.swin.edu.au/sao/guest/walter/

Historical Geology Spring 2005

Historical Geology
Spring 2005