1. Mars Astronomy 311 Professor Lee Carkner Lecture 14

2. Mars -- The God of War 

3. The Canals of Mars  In 1877 G. Schiaparelli thought that he saw intersecting straight lines on Mars    Percival Lowell built an observatory near Flagstaff, AZ and published elaborate maps of a network of canals and oasis on Mars 

4. Mars Facts  Size: ~1/2 Earth size   Orbit: 1.5 AU   Description:

5. Celestial Motions of Mars  Mars rotates on its axis with a period of 24 1/2 hours   Mars has an orbital period of 23 months   Mars is tilted on its axis 

6. Spacecraft to Mars  Mariner 4 was the first spacecraft to visit Mars in 1964   Recent missions:    Mars Express (2003, orbiter)  Mars Reconnaissance Orbiter (2006, orbiter)   Spirit and Opportunity (2003, rover)

7. Surface Features  Volcanoes -- Mars has many shield volcanoes, but they are not active today   Canyons -- Mars shows deep canyons, the result of volcanic activity stressing the crust   Craters --The northern hemisphere is less heavily cratered than the southern     Dust storms alter the Martian craters

8. Tharsis Rise

9. Olympus Mons

10. Valles Marineris

11. Cratering on Mars

12. Mars Topological Map

13. The Surface of Mars  Mars is red due to iron oxide (rust) in the soil    Surface is covered with reddish soil and is rocky and broken  Mars is cold    Mars has seasons due to the tilt of its axis

14. Standing on Mars

15. Mars’s Atmosphere  Composition: 95% CO 2, 3% N 2, trace amounts of water vapor and oxygen  Pressure: 0.007 atmospheres   Early Mars may have had a thicker CO 2 and H 2 O atmosphere  

16. Water on Mars  Mars is now a very dry world    Water ice may be present in the polar ice caps (along with frozen CO 2 )   It is possible that water exists underground

17. Frost on Mars

18. Polar Ice Cap

19. Was Mars Wet?  Surface features indicate that water once flowed freely on the Martian surface   Due to:  Global water (Many oceans, rivers, etc)?   Mars may have been warmer with a thicker atmosphere in the past   Where is the water now?    Mars may warm up periodically allowing water to form (Mars may now be in an ice age)

20. Dried-up River Bed

21. Past Water Erosion on Mars

22. Life on Mars?  Mars shows evidence for liquid water and higher temperatures in the past    Viking tested soil samples but the results were inconclusive  We do have a few meteors that were blasted off the surface of Mars   AH84001 shows some features that look a little like the remains of life-forms, but evidence is not very strong

23. Viking’s Soil Scoop

24. Fossil Life in Martian Meteorite?

25. Cydonia “Face” on Mars

26. Traits of Psuedoscience  Certainty   Avoidance of Occam’s Razor   Paranoia 

27. Mars’s Interior  Mars has a lower density than the other terrestrial planets (4000 compared to 5000 kg/m 3 )   No evidence for plate tectonics  We have very little other data on Mars’s interior  

28. Continuing Mars Exploration  Phoenix, a small “scout” lander mission, to be launched 2007   Sample return?   Manned mission? 

29. A Possible History of Mars  Mars forms   Volcanism creates volcanoes and lava flows   Mars losses internal heat, crust cools   Atmosphere loses CO 2, atmosphere cools   Water freezes

30. Summary  Red, dusty, thin atmosphere  Mars is a medium-sized world allowing it to retain an atmosphere (unlike Mercury and the Moon), but not a thick atmosphere (like Venus and Earth)  Mars shows signs of being habitable in the past, but no good evidence of life has been found

31. Summary: Surface  Mars has a red surface composed of dust, soil and rocks  Mars has large volcanoes and deep chasms  Dust storms often cover the surface  Mars has a low density and may not have an iron core

32. Summary: Climate  Mars has a very thin atmosphere and is cold  Low temperature and pressure prevent liquid water on the surface  Mars must have had a thicker, warmer atmosphere in the past since there is substantial evidence for water flows  Early thicker CO 2 greenhouse atmosphere gradually washed out by rainfall  The temperature on Mars may change over time due to orbital variations