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Home , Composition of Mars

Lattimer, AST 248, Lecture 19 – p.1/16

Mars in History Lattimer, AST 248, Lecture 19 – p.2/16

Mars in History Lattimer, AST 248, Lecture 19 – p.3/16 Lattimer, AST 248, Lecture 19 – p.4/16 d other lava sive lava plains

Mars Mass (1/10), radius (1/2) and(.7–.9%) atmosphere smaller than ’s. Rotation rate is nearly that of Earth’s. Reddish color due to oxide. • • • flows epoch: before 3.5 Gyr;surface oldest features ( bulge) and late, extensive flooding epoch: between 1.8 and 3.5Amazonian Gyr; epoch; formation after of 1.8 exten Gyr; formation of an • • • Lattimer, AST 248, Lecture 19 – p.5/16

Mars Geology Has craters and high volcanosthan (higher on Earth due to lower gravity). No active volcanos or geologiclast activity 1–2 for Byrs, due totherefore low less mass radioactivity. and Valles Marineres is a large(7 canyon km deep, 100 kmacross wide, planet), stretches formed 1/4 by crackingcrust of as Mars cooled. • • • Lattimer, AST 248, Lecture 19 – p.6/16

Mars Topography Lattimer, AST 248, Lecture 19 – p.7/16 ) 2 , 2 2 O, 0.01% NO , 1.6% Ar, 0.2% O 2 2 O mostly, with surface CO 2 , 2.7% N 2 of water, so no liquid water

Mars Atmosphere 0.07% CO, 0.01% H Polar caps (H Atmosphere only 0.7% of Earth’s,triple below point the 95.7% CO possible at any temperature. which grow and shrink according to the seasons. • • • Lattimer, AST 248, Lecture 19 – p.8/16 2 Dust loading

Mars Dust Storms catastrophically develops into storms like a super Dust Bowlto (no block vegetation it). High velocity winds and giantstorms dust on occasion. Winds causedlarge by temperature differences between day/night and pole/equator and bycondensation/evaporation. CO • Lattimer, AST 248, Lecture 19 – p.9/16 and runoff channels. Near-saturation of

Mars and Water outflow atmosphere with water indicates presence of subsurface ice (permafrost). Evidence for water in past: • Lattimer, AST 248, Lecture 19 – p.10/16 New deposits in gullies suggest and Mars Rovers

Mars and Water confirmed past existence of liquiddiscovering water ’blueberries’ by (nodules from leaching of to surfaces)which that had formed been in eroded rocks and layered by water. Right: Below: water carried through thembetween sometime 1999 and 2005. Lattimer, AST 248, Lecture 19 – p.11/16 Mars from Pathfinder . Runaway Refrigerator effect . Where did this gas go? , some froze into polar caps, O and their loss from atmosphere. 2 2 2

Mars Evolution Crater from Opportunity and H 2 Original wastimes 600 as dense, similar tothickness present of Earth’s atmosphere, and mostly CO ’ surface dissolved some CO Lack of ozone layer ledN to UV dissociation of Cooling and solidification of ironloss core of led to magnetic fieldwind and stripping to of solar- atmosphere. Net result is Mars is not necessarily toobe far Earth-like, from but Sun it to isgravity, too too small rapid (not cooling) enough toevolution prevent compared divergent to the Earth. some lost to catastrophic impacts. • • • • • • , then 2 14 Lattimer, AST 248, Lecture 19 – p.12/16 ient (“chicken ganisms. ioactive C ges. variety of reactions tive CO and CO changes. O/nutrient: 2 . Organic gases trapped, checked for radioactivity. K

Viking Experiments that mask biological activity. Gas exchange (GEX) — Soil sample placed in contact with a nutr Labeled release (LR) — Soil sample placed in contact with rad Pyrolitic release (PR) — Soil sample incubated with radioac Liquid water cannot exist on Mars today, so it could trigger a The “chicken soup” might end up being poisonous to Martian or soup”), Gas chromatograph analyzes the atmosphere for chan heated to 1023 nutrient. Radiation detectors monitors the atmosphere for • • • • • PR experiment designed without H Lattimer, AST 248, Lecture 19 – p.13/16 ple. However, oard experiments nic reactions of soil Drilling Laboratory ct observed, at organic molecules s served on Earth. considerations weight including food extraction and recycling . 2 O. 2

Viking Experiments Second wetting produced no furtherin response, nutrient suggesting reacted th with O-rich soil and produced CO although should already have been killed. GEX — Large amounts of O released, later attributed to inorga LR — Wetting produced rise in radioactivity, greater than ob PR — Radioactive C became part of the compounds in the soil sam Phoenix – launched August 2007; will haveMars robotic Science arm Laboratory and – onb rover and experiments Mars Scout – inexpensive, small probes withMars limited Sample mission Return, Astrobiology Field Laboratory and Deep Tremendously increased costs of transporting astronauts’ Risks astronaut’s Danger of contamination History shows they will be based on political, not scientific and H when soil sample pre-heated at high temperatures, same effe and -support, including radiation shielding and water • • • • • • • • • • • Results: Future Plans Disadvantages of manned missions: Lattimer, AST 248, Lecture 19 – p.14/16 Thermal emission spectrometers Mars was at one timeand in wet, its with past water warm existingstate in and its a liquid thicker atmosphere. Mars weather and climate radiation hazards (martian radiation environment experiment) gamma-ray spectrometer subsurface chemistry and water thermal emission imaging system for detecting past water () Exploration for evidence of water Mars and flyby • • • • • • • • 1996 Mars Pathfinder, rover 1996 Mars Odyssey, Mars Surveyor Orbiter 2001 Mars Rovers: Spirit and Opportunity 2003 Rosetta

Recent Mars Missions • • • • • • Lattimer, AST 248, Lecture 19 – p.15/16 SNC : unusually young ages,planet, formed blasted on into a space andrays exposed after to formation. cosmic Hard toMercury, blast Venus or matter Earth off intoimplying Earth-crossing Mars orbit, or Moon origin.identical Trapped to gases atmospheric nearly composition ofThree Mars. groups of SNC meteorites:

Did Life Once Exist on Mars? 1. formation age 4.5 Byrs,2. impact age ( formation time) age 15 1.3 Myrs; Byrs,3. impact age (transit formation time) age 12 170 Myrs; Myrs, impact age (transit time) 3 Myrs. Lattimer, AST 248, Lecture 19 – p.16/16 a. cosmic dust. nce. d water on Mars. . result of biological , 1/100 thickness of ns (PAH) whose liquid water permeating alse. biochemists, as there is s that some ogical activity. onies. e of former life in ALH ssociated with contamination unlikely. S higher than in Earth life. 34 S/ , spherical crystals formed as carbonate precipitates from human hair, the same size as the smallest known Earth bacteri no evidence of cell walls, reproduction, growth, or cell col Carbonate grains have a layered structure, indicatingCarbonate biol grains contain shapes resembling Earth bacteria Carbonate grains contain biominerals, possibly formed as a Carbonate grains contain complex polyaromatic hydrocarbo Coincidence of 3.6 Byr globule age with the presence of liqui There are nonbiological ways to produce layeredExtremely small size of nanobacteria-like shapes disturbs 32 Discovery of terrestrial microorganisms in show Previous claims of “life” in meteorites have always proved f activity (, pyrrhotite, and greigite). concentration increases with depth, implyingThese terrestrial PAHs differ from those observed in other meteorites or contamination has occurred, and could explain the PAH evide • • • • • • • • • • Recently, a NASA team announced84001, possibly which detecting landed evidenc in Antarcticaglobules 13,000 yrs ago. Evidence a BUT: the rock 3.6 Byrs ago:

Did Life Once Exist on Mars?