Mars Meteorite 28 September 2016 11/18/2018

Quiz 1 results Range: 11-100 Average: 71 Curve: B: 70-79 C: 60-69 D: 50-59 General advice: Write the answer to the question asked! Extra words and sentences can cost you if incorrect. Proofread and check your answer. Most of the correct answers were on the review sheet 11/18/2018

11/18/2018

11/18/2018

11/18/2018

11/18/2018

Meteorites from Moon, Mars Found in Antarctica: It is easy there More than 40 from Moon, more than a dozen from Mars Igneous rocks (from molten material)… ages 0.2-1.3 billion years old Trapped gases are the same as Mars atmosphere measured by Vikings One found in 1984 may show evidence of life 11/18/2018

Pictured: An Ancient Martian? 11/18/2018

controversial: contamination? Meteorites from Mars Contains magnetite associated with certain microorganisms But only 25% of the magnetite probably associated biologic activity evidence of pre-terrestrial aqueous alteration polycyclic aromatic hydrocarbons Structures resembling the mineralized casts of terrestrial bacteria but too small – nano-bacteria? ALH84001 Found in Antartica (in Allen Hills) in 1984 It was ejected from Mars about 17 million years ago and spent 11,000 years in or on the Antarctic ice sheets controversial: contamination? Composition analysis by NASA revealed a kind of magnetite that on Earth, is only found in association with certain microorganisms. 25% of the magnetite occurs as small, uniform-sized crystals that, on Earth, is associated only with biologic activity, and that the remainder of the material appears to be normal inorganic magnetite. The meteorite displays indication of relatively low temperature secondary mineralization by water and shows evidence of pre-terrestrial aqueous alteration Evidence of polycyclic aromatic hydrocarbons (PAHs) have been identified with the levels increasing away from the surface. Structures resembling the mineralized casts of terrestrial bacteria but too small – nano-bacteria?

Did life on Earth come from Mars? Meteorites from Mars Yamato 000593 (from Yamato Glacier, Antarctica) formed about 1.3 billion years ago from a lava flow on Mars contains evidence of past water alteration Nakhla (from Egypt desert) Contains polycyclic aromatic hydrocarbons but probably contaminated controversial Did life on Earth come from Mars?

But… Non-biological explanations are possibel and not ruled out Some veins require high temperature, not consistent with life (200- 500 C) Fossil is too small, similar structures can form without life Most scientists doubt that ALH84001 shows life This may only be resolved by returned Mars samples 11/18/2018

Do we have a proof that life exists on Mars? Do we have a proof that life does NOT exist on Mars? Do we have a proof that life NEVER existed on Mars?

What have we learned? Old ideas that Mars had plants and inhabitants were disproved by the first space missions Mars had much more liquid water in its past, but it is too cold for liquid water on the surface now Mars may have water today, though minimal and very salty: frozen at poles, buried as permafrost; the rest lost to space Viking experiments failed to detect life: positive results from chemistry, not biology; but only looked for Earth-like life Curiosity finds methane variations, possible life indicator? Martian meteorite probably does not show life Follow the water!