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summary Phys 1810 Lecture 14: Recall column Total Lunar Eclipse on Wednesday Oct 8! Mid-eclipse at 5:55 am. READ BEFORE LECTURE: – Solar System Chapt 6 – angular momentum (“precisely” box 6-1) – formation of the moon 8.8 – exoplanets Chapt 15 • Also can read up on comet structure. Tour of the Solar System: Mars Recall column summary Mars Global Surveyor Mars Orbiter Camera NASA/JPL/Malin • • • • Radius ~ ½ of Earth’s; Mass ~ 1/10 of Earth’s. Water ice crystals over volcanoes Pole has water ice and CO2 ice. Red soil due to iron. Martian Atmosphere. summary Recall column • Given the atmospheric pressure can liquid water currently exist on the surface of Mars? Curiosity Rover --- 7 Minutes of Terror Recall column summary Curiosity Rover summary Recall column • Mount Sharp: How does your mountain grow? • A drill hole by Curiosity at mount base • Will test in its onboard lab for chemistry • For comparison with different heights on different Martian features summary Curiosity Rover Recall column • tilted ancient stream bed? Curiosity Rover summary Recall column • conglomerate rock • Gravel: size & shape consistent with transport by H2O Sedimentary Rock Layers Recall column • deposited weathered remains of other rocks OR • precipitation from solution summary Soil summary Recall column • iron-rich clay red colour • “blueberries” could form by either volcanic processes or water related accretion processes. Gullies summary Recall column • Perhaps permafrost just under the surface heats up and escapes at these embankments and forms gullies. summary Recall column summary Recall column • However this is most likely to be a simple avalanche of debris. NASA's Mars Reconnaissance Orbiter Recall column Gullies caused by Dry Ice (frozen CO2) summary summary Desiccation Patterns Recall column Earth When lakes evaporate; mud dries out. Mars (in crater) Permafrost contractions for small pattern. Models suggest evaporating lake for large pattern. Desiccation Patterns Recall column • liquid water between 4.5 and 3.8 billion years ago. • could occur more recently due to meteorite impact melting permafrost which fills crater with liquid water under a thick layer of ice. • many thousands of years to sublimate a whole lake. summary summary Polar Cap: IR images Recall column • Polar Ice caps. • CO2 in the middle panel • H20 in left panel Phoenix Landing Recall column Mars Reconnaissance Orbiter /NASA summary Mars Polar Caps Recall column summary Phoenix/NASA • Subsurface water under ice caps good place for microbes (extremophiles) or past evidence of life. • Phoenix check conditions. summary Perchlorates Recall column The Phoenix mission to Mars discovered a chemical that a)is food for some microbes on Earth. b) is toxic to some microbes on Earth. •Toxic for humans • evidence of carbon compounds c) collects water from an atmosphere. d) is capable of creating on Mars wet habitats that are about the size of sand grains. In past, warm humid conditions BENEATH surface suitable. summary Mars and cosmic rays Recall column • Lacking protective magnetosphere. Tour of the Solar System: Mars Recall column summary Mars Express/ESA • Spectacular images! • http://www.esa.int/SPECIALS/Mars_Express/ind ex.html • http://www.nasa.gov/worldbook/mars_worldbo ok.html Citzen Science Recall column summary • Check out “Be a Martian” by NASA and Microsoft. • Map room global mosaic of Mars. • Count craters to help determine ages of regions. summary Astrobiology Recall column Detecting Our Martian Cousins Some scientists believe that if life exists on Mars, it could have been delivered there from Earth on interplanetary meteorites. With funding from NASA’s ASTEP program, a team of researchers is now putting together an instrument that could test this theory. The Search for Extraterrestrial Genomes (SETG) project would send an instrument to Mars to search soil or ice samples for the presence of Earth-like DNA. • http://astrobiology.nasa.gov/ • Search for water associated with extrasolar planets. • Study extremophiles on Earth. summary Recall column • Discuss with your neighbours which aspect of Mars is of most interest to you. What do you think of colonizing Mars? summary Recall column Tour of Solar System Ends Overview of Solar System • Relevant to Solar System Formation Solar System Overview summary Recall column • The density in kg/m3 – 1000 for water; if less than this, floats in water. – 2000-3000 for rocks; 8000 for iron • Note 2nd last column & density of Earth. • Ask yourself which planets have densities like rocks/iron? Float on water? Solar System Overview: Recall column summary • For each planet: – revolve & rotate in the same direction as other planets? – primarily composed of rock or of gas? # Earth Masses, # Earth radii – small or large? (i.e. closer to Earth size or Jupiter size?) – in outer region or inner region of solar system? – hot or cold? surface T in Kelvin – Lots of moons? – Any other details are welcome (eg. Does it have rings? B field?) Solar System Overview: summary Recall column • Terrestrials: Mercury, Venus, Earth, Mars • Jovians: Jupiter, Saturn, Uranus, Neptune Distances in the Solar System summary Recall column Voyager 1 location and edge of the solar system? Extent of Sun’s gravitational influence. • Kuiper Belt: – Debris from solar system formation – Contains dwarf planets larger than the dwarf planet Pluto • Oort Cloud: – Comets come from these distances Planetary System Example: summary Recall column Dan Foley • Asteroids 0 – 5.2 AU (i.e. Jupiter’s orbit) - main Belt between Mars & Jupiter • Kuiper Belt is thicker than the Asteroid Belt • Oort Cloud is spherical summary Dwarf Planets: Recall column Dan Foley • Ceres in Asteroid Belt • Kuiper Belt summary Solar System Overview: Interplanetary Debris Recall column Comet Holmes (Pierre Tremblay 2007) Asteroids visited by spacecraft up to 2008. NASA Type Asteroids Meteroids Comets Diameter > 100m < 100m 1 – 10 km Category rocky rocky icy Comet Ison – approach sun Nov 2013 Recall column • copyright: Damien Peach summary Comet Lovejoy: Coma, ion tail, dust tail Recall column • copyright: Damien Peach summary 67P/C-G on 26 September from a distance of 26.3 Recall column km. Credit: ESA/Rosetta/NAVCAM summary • activity at the neck • product of ices sublimating & gases escaping from inside comet, carrying streams of dust out into space Recall column Many scientists define the “edge” of the solar system as the region where the gravitational influence of the sun is too weak to retain comet material in orbit. What is the extent of the solar system? a) 5.5 light-hours i.e. the orbit of Pluto b) 100,000 AU i.e. the outer region of the Oort Cloud c) a few 100 AU i.e. the outer region of the Kuiper Belt d) 125 AU i.e. the point the Voyager 1 space craft passed Sept 2013 summary How do we define the edge of the solar system? summary Recall column • Interstellar Boundary Explore IBEX. • Heliosphere – bubble blown by solar wind has structure How do we define the edge of the solar system? summary Recall column • Interstellar Boundary Explore IBEX. • The influence of the solar wind ends beyond the Heliopause- between 120 & 150 AU. Where is Voyager 1? summary Recall column So in the Kuiper Belt! Not at the edge of the solar system defined by the Sun’s gravitational pull (outer edge of Oort cloud). • 125 AU from Earth, and is expected to take roughly 300 years to reach the inner edge of the Oort Cloud and some 30 000 years to escape it entirely. Interstellar Space – can be defined as beyond influence of solar wind summary and sun’s magnetic field. Recall column Solar System Formation Recall column summary To understand this we use: • facts about planets & asteroids, meteors & comets • physics e.g. – properties like temperature – Newton’s Laws of Motion & gravity – Angular Momentum summary Angular Momentum Recall column • Angular Momentum == tendency of a body to keep spinning (rotating) or moving in a circle (revolving) (#revolutions/sec) CONSERVATION OF ANG. MOM.