Introduction to Mars PTYS/ASTR 206 3/22/07

Transcription

1 Introduction to

2 Reading Assignment Finish Chapter 13 Announcements Quiz today Will cover all material since the last exam. This is Chapters 9-12 and the part of 13 covered today. Exam #2 next Thursday Brief review after Tuesday s lecture Next study-group session is next Wednesday (3/28) from 10:30AM- 12:00Noon in room 330. Public lecture next Tuesday (3/27) 7:30PM in 308 of Kuiper (this room). Prof. Bob Brown, Saturn seen through infrared eyes Look for PTYS/ASTR206 sign-up sheet (our class!) Note Prof. Brown will conduct a limited number of special 10- minute tours of the VIMS Operations Center; these tours will originate in the Atrium at 6PM early arrival is recommended!

3 Today: Basic facts of s apparitions / orbit / appearance from Earth Exploration Surface (start) Tuesday Surface (finish) Interior Atmosphere Water on Moons Life (time permitting; otherwise, this will be discussed later in the course)

4 Introduction to 4 th planet from the Sun Avg. distance: AU Eccentricity: Year: days Day: hours Almost the same (differs only by about ½ hour) Diameter: 6,794 km About ½ the size of Earth Mass: x kg About 10 times less than Earth Surface temp: Max: 70 o F Min: -220 o F Mean: -63 o F

5 Apparitions is best seen from Earth every synodic period. That is every 780 days. During this time, is at opposition and rises to its highest point in the night sky at midnight. During the month or so on either side of this, is bright in the sky and is very obvious also known as an apparition Because of s elliptical orbit, some oppositions are more favorable than others An especially good apparition occurred in 2003 when was at its closest to Earth in over 50,000 years.

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8 Synodic vs. Sidereal Orbital Period Sidereal Period: The time it takes a planet to complete a single orbit about the Sun (as seen from the stars) Synodic Period: Time interval for a planet to return to the same position relative to the Sun and Earth (i.e. the time between successive oppositions) has the longest synodic period of ALL the planets

9 Synodic vs. Sidereal Periods MARS EARTH SUN

10 Synodic vs. Sidereal Periods 6 months later SUN EARTH MARS

11 Synodic vs. Sidereal Periods MARS 1 year later EARTH SUN

12 Synodic vs. Sidereal Periods MARS 1.5 years later SUN EARTH

13 Synodic vs. Sidereal Periods 2 years later EARTH SUN MARS

14 Synodic vs. Sidereal Periods 1 Synodic Period Later SUN EARTH MARS

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16 Earth-Based Views of Ground-based telescope Hubble Space Telescope

17 A Gallery of my attempts summer of 2003

18 Early Observations Astronomers in the 1600s made the first telescopic observations of They determined: Rotation period (24 h 37m) Presence of ice caps 25 o tilt Linear features Canali (italian for channels) Mistranslated as canals

19 Percival Lowell Background Wealthy Bostonian Brother was president of Harvard Sister won a Pulitzer prize in poetry Math degree from Harvard Decided to build an observatory in Flagstaff Realized importance of seeing conditions After the craze, spent the rest of his life searching for planet X Saw LOTS of canals

20 Lowell s interpretation Canals carry water from Ice caps to civilizations in the agricultural regions The civilizations were dying of thirst Evidence for intelligent life on

21 They are not there! Canals: Reality Lowell almost certainly was playing connect the dots An easy trap to get into Observing fine details on small objects through a telescope is a tough business! Note that they could magnify the images considerably, but that atmospheric turbulence limits what can be seen at such high magnification

22 This was seen in Viking mission images Optical effects again The Face on Suggestive of something built by a civilization Not proposed by a scientist Scientists never accepted this interpretation

23 The Face at higher resolution as seen with Global Surveyor MOC camera

24 More familiar features

25 A History of Exploration Mariner 4 (1965) Found that has many craters

26 A History of Exploration Mariner 4 (1965) Found that has many craters Mariner 9 (1971) Found several enormous Volcanoes Not so dead!

27 A History of Exploration Mariner 4 (1965) Found that has many craters Mariner 9 (1971) Found several enormous volcanoes Not so dead! Viking (1976) Lander, Compete map of surface (Face on mars) Biological experiments (no life!)

28 More Recent (and Future) Missions Pathfinder (1997) Global Surveyor (1997) Both missions in 1999 failed Stupid mistakes Odyssey (2001) Water on! (UA instrument) Express (rover Beagle failed) (2003) Exploration Rovers: Spirit and Opportunity (2003) These are still going strong (would make for an excellent mission update ) 05 Reconnaissance Orbiter Successful orbit insertion HIRISE (UA instrument) you have GOT to check out their website!!! 07 Phoenix lander (UA mission!)

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30 HiRISE view of a rover next to Victoria crater

31 Another HiRISE image

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33 The heavily cratered southern highlands are older and about 5 km higher in elevation than the smooth northern lowlands Fewer craters in the Northern lowlands s surface The origin of s crustal dichotomy is not completely understood One giant impact basin? Multiple large impact basins? Plate tectonics?

34 A rift valley that separates the Northern and southern regions 3000-miles long As much as 6 miles deep in places Valles Marineris formed by upwelling plumes of magma in the mantle

35 Olympus Mons is an enormous shield volcano 27 km high 20 times wider than it is high s Volcanoes It is not active, and neither is any other volcano on has the largest shield volcanoes in the solar system

36 is much more heavily cratered than the Earth and Venus s Craters Has regions with similar crater density to that found at Mercury and the Moon The largest (more than 50km wide) and smallest (less than 5 km) craters are similar to those found on the Moon and Mercury

37 Medium sized craters (~ km) have large ejecta blankets which come in a variety of shapes Pancakes Flowers (as shown) May be due to subsurface water Like a pebble in mud NOT CLEAR! Splosh Craters

38 s Interior Density is 3950 kg/m 3. This is somewhat less than Earth's density. Also, is smaller than the Earth, so it could have cooled off more inside. Sulfur rich? Magnetic field: has no global magnetic field.