Astronomy 101 The Solar System Tuesday, Thursday 2:30-3:45 pm Hasbrouck 20 Tom Burbine tomburbine@astro.umass.edu
Course Course Website: http://blogs.umass.edu/astron101-tburbine/ Textbook: Pathways to Astronomy (2nd Edition) by Stephen Schneider and Thomas Arny. You also will need a calculator.
Office Hours Mine Tuesday, Thursday - 1:15-2:15pm Lederle Graduate Research Tower C 632 Neil Tuesday, Thursday - 11 am-noon Lederle Graduate Research Tower B 619-O
Homework We will use Spark https://spark.oit.umass.edu/webct/logondisplay.d owebct Homework will be due approximately twice a week
Astronomy Information Astronomy Help Desk Mon-Thurs 7-9pm Hasbrouck 205 The Observatory should be open on clear Thursdays Students should check the observatory website at: http://www.astro.umass.edu/~orchardhill for updated information There's a map to the observatory on the website.
Final Monday - 12/14 4:00 pm Hasbrouck 20
Due today HW #18 and #19
Registered Students Class Average 100 90 80 70 60 A or A- B+, B, or B- C+, C, or C- D+ or D 50 40 30 20 10 F Median Grade is an 81 Without Dropping Lowest Grades 0 0 10 20 30 40 50 60 70 80 90 100 Exam Average
Four Science Goals of NASA's long-term Mars Exploration Program: Determine whether Life ever arose on Mars Characterize the Climate of Mars Characterize the Geology of Mars Prepare for Human Exploration
Mars Pathfinder Landed July 4, 1997 Weight - 870 kg Lasted 3 months Discovery Mission
Objectives of Mars Pathfinder Discovery Mission - To prove that the development of "faster, better and cheaper" spacecraft is possible (with three years for development and a cost under US $150 million). To show that it is possible to send a load of scientific instruments to another planet with a simple system and at one fifth the cost of a Viking mission. To demonstrate NASA's commitment to low-cost planetary exploration finishing the mission with a total expenditure of US$ 280 million, including the launch vehicle and mission operations.
Sojourner Rover is investigating Yogi the Rock
Spirit and Opportunity I used to live in an Orphanage. It was dark and cold and lonely. At night, I looked up at the sparkly sky and felt better. I dreamed I could fly there. In America, I can make all my dreams come true... Thank-you for the "Spirit" and the "Opportunity" Sofi Collis, age 9
Spirit landed in Gusev Crater appeared basaltic Opportunity landed on Meridiani Planum appeared to have lots of sedimentary rock
Spirit
Rover tracks
Made by the RAT Rock Abrasion Tool
Husband Hill
Opportunity
Opportunity Ledge Rocks seem layered. Either due to sediments or volcanic ash
Hematite (Fe 2 O 3 ) formed as deposits in water?
Spirit and Opportunity- now Both completed their planned 90-day missions Both have completed over 2,100 days Still functioning Spirit has a broken wheel Opportunity s shoulder joint on its robotic arm is broken Spirit is now stuck in soft soil
Taken by Spirit http://commons.wikimedia.org/wiki/file:pia05547-spirit_rover-earth_seen_from_mars.png
Phoenix Part of Mars Scout program First mission run by a university Landed near Martian North Pole Dig trenches to search for water Launched August 4, 2007 Landed May 25, 2008 Mission concluded November 10, 2008 http://en.wikipedia.org/wiki/image:phoenix_landing.jpg
http://en.wikipedia.org/wiki/image:phoenix_lander_seen_from_mro_during_edl2.jpg
Devon Island http://en.wikipedia.org/wiki/image:patterned_ground_devon_island.jpg This polygonal cracking is similar to patterns seen in permafrost areas A likely formation mechanism is that ice contracts when the temperature decreases, creating a polygonal pattern of cracks When the temperature rises and the ice expands back to its former volume, it can t assume its former shape It then buckle upwards. http://en.wikipedia.org/wiki/image:phoenix_mission_horizon_stitched_high_definition.jpg
http://en.wikipedia.org/wiki/image:evaporating_ice_on_mars_phoenix_lander_image.jpg
Terrestrial Planets Have different surface properties Due to size of the planet Distance from Sun Speed of Planetary Rotation
Meteors
Shaping Planetary Surfaces Impact Cratering Volcanism Tectonics Erosion
Cratering Meteor Crater, Arizona http://www.solarviews.com/eng/tercrate.htm
Galle Crater, Mars
Mercury http://geologyindy.byu.edu/eplanet/chapter_5.htm
Callisto (Moon of Jupiter) http://ase.tufts.edu/cosmos/view_picture.asp?id=726
Earth s atmosphere Small asteroids burn up in the Earth s atmosphere before they hit the ground Any craters that do form are quickly eroded by weather generated in the atmosphere
Volcanism
Erosion Processes that break down or transport rock through the action of ice, liquid, or gas Movement of glaciers Formation of canyons by running water Shifting of sand dunes by wind
Energy of Impact (K-T) v = 17 km/s Density = 3,000 kg/m 3 Diameter = 2*radius =10 km Volume = 4/3*π*r 3 = 5.23 x 10 11 m 3 Mass = density*volume Mass = 1.57 x 10 15 kg Kinetic energy = ½ mv 2 Kinetic energy = 2.27 x 10 23 Joules Kinetic Energy = 5.42 x 10 7 Megatons of TNT Largest Nuclear Bomb is 100 Megatons of TNT
Result of all this Energy Rock melts Cools quickly to form glass
Gene Shoemaker Parts taken from talk of Bridget Mahoney
Meteor Crater, Flagstaff, Arizona Shoemaker wrote his Ph.D thesis on Meteor Crater Shoemaker did seminal research in the mechanics of meteorite impacts
Meteor Crater and Shoemaker In 1952, Shoemaker hypothesized that Meteor Crater as well as lunar craters were created by asteroidal impacts USGS sent Shoemaker to the Yucca flats to investigate small nuclear events to compare with Meteor Crater, Shoemaker at Meteor Crater, 1960 s
Coesite While doing research in the Yucca flats on meteorite impact with David Chao, the pair discovered Coesite Coesite (SiO 2 ) is a mineral that is produced during violent impact earth.leeds.ac.uk
Chixculub Crater Taken from presentation by Amanda Baker
65 million years ago Boundary in the rock record separating the Cretaceous and Tertiary Periods Corresponds to one of the greatest mass extinctions in history Global layer of clay separating the two periods First proposed by Walter Alvarez K-T Boundary
We know it happened but where? A Circular geophysical anomaly, now known to define the Chicxulub structure, was originally identified on the northern edge of the Yucatan Peninsula during oil surveys in the 1950's.
Chixculub Translates to tail of the devil in Mayan The meteorite's estimated size was about 10 km (6 mi) in diameter, releasing an estimated 4.3 10 23 joules of energy (equivalent to 191,793 gigatons of TNT) on impact.
Chixculub Impact http://www.lpl.arizona.ed u/sic/impact_cratering/c hicxulub/animation.gif
Seismic, gravity and magnetic data define a structure ~180 km in diameter. Data
What happened? An asteroid roughly 10 km (6 miles) across hit Earth about 65 million years ago. This impact made a huge explosion and a crater about 180 km (roughly 110 miles) across. Debris from the explosion was thrown into the atmosphere, severely altering the climate, and leading to the extinction of roughly 60% of species that existed at that time, including the dinosaurs.
Environmental Damage http://www4.tpgi.com.au/users/horsts/climate.htm
The worst hit organisms were those in the oceans. On land, the Dinosauria of course went extinct, along with the Pterosauria. Mammals and most non- dinosaurian reptiles seemed to be relatively unaffected. The terrestrial plants suffered to a large extent, except for the ferns, which show an apparently dramatic increase in diversity at the K-T boundary, a phenomenon known as the fern spike.
Pterosaurs were flying reptiles
Dinosaurs lived during the Mesozoic Era, from late in the Triassic period (about 225 million years ago) until the end of the Cretaceous (about 65 million years ago).
Modern birds are considered to be the direct descendants of dinosaurs
Tunguska Occurred in 1908 Huge explosion in the atmosphere Thought to be asteroid or comet that exploded in mid-air 6 to 10 kilometers above the Earth's surface Energy of 10 and 15 megatons of TNT Equivalent to the most powerful nuclear bomb detonated in the USA There wasn t a large expedition to the site until 1927
http://en.wikipedia.org/wiki/image:tunguska_event_fallen_trees.jpg
http://thunderbolts.info/tpod/2006/image06/060203tunguska2.jpg
http://geophysics.ou.edu/impacts/tunguska_dc.gif
Evidence for extraterrestrial impact No large meteorite fragments were found Found were microscopic glass spheres that contained high proportions of nickel and iridium
Other ideas http://en.wikipedia.org/wiki/tunguska_event
Craters Tend to be round unless it is an oblique impact Tycho crater on Moon Diameter 85 km Depth 4.8 km http://en.wikipedia.org/wiki/impact_crater
Moon (180 x 65 km). Mars (380 x 140 km) http://www.boulder.swri.edu/~bottke/oblique_craters/oblique.html
Craters
Complex craters tend to be larger than simple craters
Complex Craters gravity causes the steep crater walls to collapse, which makes complex craters very shallow Central uplift where the earth rebounds from the impact
Complex Peak Ring Central peak Collapses (Melosh, 1989)
Different types of craters http://www.classzone.com/books/earth_science/te rc/content/investigations/es2506/es2506page07.cf m
Small craters are usually much more common than larger ones http://mars.jpl.nasa.gov/gallery/craters/hires/gusev(plain).jpg
More craters at smaller sizes - older
Late Heavy Bombardment A period of time approximately 3.8 to 4.1 billion years ago during which a large number of impact craters are believed to have formed on the Moon Determined from the formation ages of impact melt rocks that were collected during the Apollo missions. Earth must have also been affected (The age dates when the rock formed.)
Dating through crater counting (Things to bear in mind) Impact rate and size distribution of impacting bodies Temporal and spatial variations in impactor population Temporal variation in the target Crater degradation Secondary impacts Need for measured surface ages to calibrate counting
Calibration Moon we have samples from specific places Other planets no samples
http://www.psi.edu/projects/mgs/chron04c.html
Cratering rate will be different on Mars compared to the Moon Mars has larger mass so larger flux (gravitational focusing) Mars closer to asteroid belt (more possible impactors)
Any Questions?