Water on Mars Haren Patel

Things you might learn When/where the water was When/where the water was Evidence for it Evidence for it Ramifications of it Ramifications of it Counters Counters What I think What I think

Timeline

Water in the Distant Past Distant past for this purpose is greater than 3.5 billion years ago Distant past for this purpose is greater than 3.5 billion years ago It is hypothesized that up to 1/3 of Mars was covered by an ocean It is hypothesized that up to 1/3 of Mars was covered by an ocean These oceans would have had These oceans would have had many inlet channels of rivers and lakes feeding into the ocean

Evidence Valleys eroded away by river flow appear in the northern hemisphere Valleys eroded away by river flow appear in the northern hemisphere Areas in the northern hemisphere have patterns consistent with shorelines Impact studies further confirms the existence of an ocean due to few craters in areas where oceans are hypothesized to have existed

The Not so distant past Since 3.5 billion years ago Since 3.5 billion years ago Almost no liquid water Almost no liquid water Most current water is in the form of ice and vapor Most current water is in the form of ice and vapor Although none of the water is in the liquid form, there is a significant amount that has shaped the geography Although none of the water is in the liquid form, there is a significant amount that has shaped the geography

Ice is stable in the latitudes greater than ± 50-60° Ice is stable in the latitudes greater than ± 50-60° As ice cools and heats, a polygonal fracture pattern forms over millions of years of repeated expansion/contraction As ice cools and heats, a polygonal fracture pattern forms over millions of years of repeated expansion/contraction Ice layers allow solute particles to be frozen in place Ice layers allow solute particles to be frozen in place As the ice sublimates the particles are exposed which give distinct erosion patterns As the ice sublimates the particles are exposed which give distinct erosion patterns

The Milankovitch cycles that occur on Mars are much more extreme, varying the tilt from 10-40° The Milankovitch cycles that occur on Mars are much more extreme, varying the tilt from 10-40° The large changes in tilt lead to large variations in the “seasons” that affect the stability of water in different regions of the planet The large changes in tilt lead to large variations in the “seasons” that affect the stability of water in different regions of the planet The cycles of heating and cooling is what led to the ability of the honeycombing features The cycles of heating and cooling is what led to the ability of the honeycombing features This cycling would allow ice from the polar regions to sublimate and move towards the equator before re-adsorbing into the soil This cycling would allow ice from the polar regions to sublimate and move towards the equator before re-adsorbing into the soil As the water went deeper into the soil, the less soluble particles in the water would be left closer to the surface and more soluble particles would travel farther down As the water went deeper into the soil, the less soluble particles in the water would be left closer to the surface and more soluble particles would travel farther down

The very recent There is still measureable amounts of water on Mars There is still measureable amounts of water on Mars The polar regions are covered by ice caps The polar regions are covered by ice caps The average amount of water vapor in a vertical column of the Martian atmosphere is about 20 precipitable microns The average amount of water vapor in a vertical column of the Martian atmosphere is about 20 precipitable microns Small amounts of ice and frost is present just under the surface Small amounts of ice and frost is present just under the surface 1% of the Martian soil is water by mass 1% of the Martian soil is water by mass

The very recent Presence of many “gullies” in canyon and crater walls Presence of many “gullies” in canyon and crater walls Erosion patterns formed from seeping of water out of the Martian soil Erosion patterns formed from seeping of water out of the Martian soil Some say seeping and gully formation stopped about 10 million years ago while others argue that many are still forming and many have appeared within the last 10 years Some say seeping and gully formation stopped about 10 million years ago while others argue that many are still forming and many have appeared within the last 10 years

So what happened to all the water? The current pressure and temperature of Mars does not allow for water to be stable as a liquid The current pressure and temperature of Mars does not allow for water to be stable as a liquid The pressure is only 6 millibar at the surface and the average temperature at the equator is 220K The pressure is only 6 millibar at the surface and the average temperature at the equator is 220K The conditions are slightly below the triple point of water so water only exists as a solid or vapor The conditions are slightly below the triple point of water so water only exists as a solid or vapor

Oceans? Current conditions may not favor liquid water but in the distant past, greater than 3.5 billion years ago, conditions were very different Current conditions may not favor liquid water but in the distant past, greater than 3.5 billion years ago, conditions were very different Although Mars was closer to the Sun than it is today, the faint sun problem that Earth would have experienced would have still not allowed the temperature to be high enough Although Mars was closer to the Sun than it is today, the faint sun problem that Earth would have experienced would have still not allowed the temperature to be high enough It is thought that the greenhouse effect is what warmed the planet up enough just as it did on Earth in the early years of the solar system It is thought that the greenhouse effect is what warmed the planet up enough just as it did on Earth in the early years of the solar system

Carbon dioxide saturates at levels not high enough to cause enough of a greenhouse effect to reach temperatures high enough for liquid water however Carbon dioxide saturates at levels not high enough to cause enough of a greenhouse effect to reach temperatures high enough for liquid water however A combination of carbon dioxide clouds and methane would have caused enough additional warming to allow for liquid water A combination of carbon dioxide clouds and methane would have caused enough additional warming to allow for liquid water

So where did the methane come from? Some abiotic reactions like the Serpentine reaction could have generated some of the methane needed Some abiotic reactions like the Serpentine reaction could have generated some of the methane needed The amount of methane proposed by models though leads to the most likely source of the methane as ancient methanogens The amount of methane proposed by models though leads to the most likely source of the methane as ancient methanogens

Sedimentary rocks at Eagle crater in Meridiani Planum are composed of fine-grained siliciclastic materials derived from weathering of basaltic rocks, sulfate minerals (including magnesium sulfate and jarosite) that constitute several tens of percent of the rock by weight, and hematite. Cross-stratification observed in rock outcrops indicates eolian and aqueous transport. Diagenetic features include hematite-rich concretions and crystal-mold vugs. We interpret the rocks to be a mixture of chemical and siliciclastic sediments with a complex diagenetic history. The environmental conditions that they record include episodic inundation by shallow surface water, evaporation, and desiccation. The geologic record at Meridiani Planum suggests that conditions were suitable for biological activity for a period of time in martian history. In Situ Evidence for an Ancient Aqueous Environment at Meridiani Planum, Mars S. W. Squyres1S. W. Squyres1,*,* J. P. Grotzinger2J. P. Grotzinger2, R. E. Arvidson3R. E. Arvidson3, J. F. Bell III1J. F. Bell III1, W. Calvin4W. Calvin4, P. R. Christensen5P. R. Christensen5, B. C. Clark6B. C. Clark6, J. A. Crisp7J. A. Crisp7, W. H. Farrand8W. H. Farrand8, K. E. Herkenhoff9K. E. Herkenhoff9, J. R. Johnson9J. R. Johnson9, G. Klingelhöfer10G. Klingelhöfer10, A. H. Knoll11A. H. Knoll11, S. M. McLennan12S. M. McLennan12, H. Y. McSween Jr.13H. Y. McSween Jr.13, R. V. Morris14R. V. Morris14, J. W. Rice Jr.5J. W. Rice Jr.5, R. Rieder15R. Rieder15 and L. A. Soderblom9

The OMEGA/Mars Express hyperspectral imager identified hydrated sulfates on light- toned layered terrains on Mars. Outcrops in Valles Marineris, Margaritifer Sinus, and Terra Meridiani show evidence for kieserite, gypsum, and polyhydrated sulfates. This identification has its basis in vibrational absorptions between 1.3 and 2.5 micrometers. These minerals constitute direct records of the past aqueous activity on Mars. Sulfates in Martian Layered Terrains: The OMEGA/Mars Express View Aline Gendrin1Aline Gendrin1,*,* Nicolas Mangold2Nicolas Mangold2, Jean-Pierre Bibring1Jean-Pierre Bibring1, Yves Langevin1Yves Langevin1, Brigitte Gondet1Brigitte Gondet1, François Poulet1François Poulet1, Guillaume Bonello1Guillaume Bonello1, Cathy Quantin3Cathy Quantin3, John Mustard4John Mustard4, Ray Arvidson5Ray Arvidson5 and Stéphane LeMouélic6

So what changed? No one knows for sure what happened to all of the carbon dioxide but there are three events that are most likely to have occurred No one knows for sure what happened to all of the carbon dioxide but there are three events that are most likely to have occurred –Some was released into space by large impacts –Some was stripped from the atmosphere by solar winds which were more intense 4 billion years ago –It reacted with surface minerals forming carbonates

Counters Lava channels Lava channels

Counters Pyroxene and feldspars Pyroxene and feldspars –Chemicals like pyroxene and feldspars react quite rapidly with water, depleting them from the environment –Both chemicals are present in large quantities and their reacted forms have not been found yet

Counters Lack of carbonates in soil Lack of carbonates in soil –Carbon dioxide readily dissolves in water forming carbonates –As the water evaporated, the carbonates and salts should have been deposited on the surface, none have been found yet –Carbon dioxide doesn’t readily dissolve in acidic water however and so carbonates would not be found, this is running explanation with evidence due to the finding of sulfur, phosphate, and chloride in the soil

Conclusions The likelihood of there being large amounts of liquid water on Mars in the past is very high The likelihood of there being large amounts of liquid water on Mars in the past is very high The increased greenhouse effect in the past due to carbon dioxide and methane would have provided sufficient heating to the planet The increased greenhouse effect in the past due to carbon dioxide and methane would have provided sufficient heating to the planet The presence of water and methane in large quantities leads to the question of whether there ever was life The presence of water and methane in large quantities leads to the question of whether there ever was life

My 2¢ I think there was a significant amount of liquid water in the past I think there was a significant amount of liquid water in the past The presence of methane was probably from methanogens living in the water The presence of methane was probably from methanogens living in the water Much of the methane that was present was absorbed deep into the depths and is probably slowly released due to the cycling in the climate that allows it to be released which is observed Much of the methane that was present was absorbed deep into the depths and is probably slowly released due to the cycling in the climate that allows it to be released which is observed

References out out out out some-times.html some-times.html some-times.html some-times.html