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Queen's University
Physics, Engineering Physics and Astronomy
ASTR 101

Mars • Mars is smaller than Earth and very difficult to study from Earth as it shows few details, even at its closest point to Earth  Mars has an eccentric orbit where it changes positions in terms of its orientation in the night sky, however this provided rare glimpses  Found polar ice caps that change size with the seasons, and dark spots that occur during different seasons which were eventually discovered to be dark rocks exposed and then covered by sand (huge windstorms occur on Mars) • Percival Lowell: Discovered 'canali' on Mars, which translates to channels which are naturally occurring, however English-speakers misinterpreted this for canals built by life forms  Sadly, this was all in his head, and his elaborate maps with detailed canals bringing water from polar ice caps to inner land was just not there  Today, we find geological features such as large rift valleys and dormant volcanoes, but nothing of the sort that Lowell "saw" • Perception of Martians was innocent by Lowell, however in Hollywood they are commonly not  Example: War of the Worlds depicted Martians as jealous of Earth since Mars was dying, thus they tried to invade (depicted as large octopus-like creatures)  Will we accept Martians if they look like puppies? What about scorpions?  Earth's gravity is 3 times of that on Mars, which will hinder Martians • Do we have a moral obligation to try not to bring disease to the planets we visit? Astronauts that came back from the moon were quarantined in case they picked up a virus from outer space Early Flybys of Mars: • 1960's: First probes that photographed Mars shattered any hopes of life on the planet as they showed a barren, moon-like surface with no evidence of life  Did not fly over geologically fascinating regions of Mars, falsely depicting what Mars was truly like  Showed that Mars had a thin atmosphere with no nitrogen and mostly CO 2 • 1970's: Mariner 9 was put into orbit around Mars, however it arrived during a dust storm, so they photographed Mars's tiny moons  Observations from Earth showed the moons were slowing in orbit, due to the fact that they were so close to Mars that air resistance in the upper atmosphere was slowing them  Theories that the moons were hollow and Martians lived in them arose...  When the dust settled, Mariner 9 discovered Mars was not a sterile moon-like body and it possesses distinct features attributed to active geology  Discovered Olympus Mons, a giant inactive volcano 3 times the height of Earth's largest mountains  Large rift valley larger than the Grand Canyon  Found sinuous river bed features consistent with water flowing  Polar caps composed of both frozen water and frozen carbon dioxide (dry ice)  Deduced that Mars once had large amounts of water and active geology facilitating plate tectonic  Active volcanism would have thickened the atmosphere and made Mars warmer and hospitable for primitive life forms • Mars Landers: Launched towards Mars and put into orbit until a suitable landing site is determined  Once found, part of the orbiter detaches and parachutes down towards the surface, but the parachute is ejected high off the ground to ensure it will not cover the lander  Rockets ensure the lander does not plummet to the ground and engines are shut off before landing so the ground is not contaminated  Shock absorbers soften the landing The Search for Martian Life • LAWKI = Life as we know it; we are searching for this kind of life as we do not yet have the means to search for exotic life forms that live in say, hot magma  We know all life forms use water as a chemical solvent and rely on carbon-based organic chemistry and interaction with atmospheric gases during metabolism  Consist of 20 essential amino acids, and so on... • Planets that are far away in other solar systems must have intelligent life forms for us to find it, since there would be no way to
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