1. 11c. Red Planet Mars Mars data Earth-based observations of Mars Early observations mistaken as evidence of life Spacecraft find craters, volcanoes & canyons Surface features indicate flowing water Earth & Mars began alike, evolved differently Rovers explored the Martian surface The Martian atmosphere changes seasonally Martian moons resemble captured asteroids

2. Mars Data (Table 13-1)

3. Mars Data: Numbers Diameter:6,794 km0.53. Earth Mass:6.4. 10 23 kg0.107. Earth Density:3.9. water0.72. Earth Orbit:2.3. 10 8 km1.52 AU Day:24 h.37 m 23 s 1.02. Earth Year:686.98 days1.88. Earth

4. Mars Data: Special Features Mars is farthest terrestrial planet from the Sun Mars is the second smallest terrestrial planet Mars has < 1% the Earth’s atmosphere –Mars’ atmosphere is ~ 95% CO 2 & 3% N 2 Mars has rapidly changing polar ice caps Mars has two very different hemispheres –The “north” is covered with volcanoes & lava flows –The “south” is covered with numerous craters Mars holds some Solar System records –Olympus Mons:The tallest mountain (a volcano) –Valles Marineris:The longest canyon Mars will be the first planet visited by humans

5. Earth-Based Observations of Mars Mars is the closest superior planet to Earth –ConjunctionAlways superior [far side of the Sun] Mars is overhead at local solar noon Mars isfarthest fromEarth & appears smallest –Opposition Mars is overhead at local solar midnight Mars isclosest toEarth & appears largest Mars’ orbit is rather highly elliptical –Mars oppositions vary in favorability Augustoppositions aremostfavorable –28 August 2003 closest in nearly 60,000 years Februaryoppositions areleastfavorable –Mars looks very small even at favorable oppositions Hubble Space Telescope cannot identify impact craters

6. Future Mars Oppositions May 22, 2016 July 27, 2018 October 13, 2020

7. Orbits of Earth & Mars

8. Mars: Hubble Space Telescope

9. Old Mars Observations From Earth Giovanni Schiaparelli1877 –Reported seeing canali on Mars Italian ⇒ Means“channels”&is ambiguous –Natural stream channels English ⇒ Translated“canals”&has implications –Artificial shipping routes –Long viewing sessions & poor seeing conditions He “saw” what was not actually there He incorrectly interpreted what he did not actually see

10. Observations As Evidence of Life Seasonal color changes do occur on Mars –WinterFine red dust settles on large lava flows Areas look relatively lightField stubbleon Earth –SummerWind removes thin cover of dust Areas look relatively darkVerdant fieldson Earth The human eye plays tricks –Astronomers stare at bright red areas on Mars Most of Mars has a distinct red color –Astronomers see cyan [blue-green] in dark areas Tendency of retinal fatigue to see complementary color Misinterpretation –“Canals” + summer greening = Intelligent life

12. Martian Canali & Craters

13. Martian Global Topography

14. Spacecraft Find Craters & Volcanoes Mariner 4, 5 & 7 –First close-up pictures of Mars –Two distinctly different hemispheres on Mars Boundary tilted ~ 30° to the Martian equator Northern hemisphereRelatively low & relatively smooth Southern hemisphereRelatively high & heavily cratered Unusual features –Valles MarinerisFly-overFly-over Longest, widest & deepest canyon in the Solar System –Would reach from San Francisco to New York –Many side canyons are as large as the Grand Canyon –Mars shows no evidence of plate tectonics As on Venus, lack of oceans may be critical here –Olympus MonsFly-overFly-over Solar System’s largest volcano Clear evidence of hot-spot volcanism

15. Valles Marineris: Hemispheric View

16. Olympus Mons: Solar System Champ

17. Surface Features Indicate Water Earth-like streamflowclearly existed on Mars –Dendriticstream channels flow downmountains Most of these appear to berelatively old –Parallelstream channels flow downslopes Many of these appear to beremarkably young Permafrost may be just beneath the Martian surface Catastrophic floodsclearly existed on Mars –Teardrop-shaped islands around crater rims Remarkably similar to Glacial Lake Missoula floods ≥ 109 floods from ~ 15,500 to ~ 13,500 years ago Biggest floods ~ 500 cubic miles of water past Portland Evidence for a Great Northern Ocean –Strandlines on northern hemisphere slopes Notches cut by wave action along shorelines

18. Dendritic Stream Channels on Mars

19. Parallel Stream Channels on Mars

20. Evidence of Sheet Flow on Mars Water Flow Direction Teardrop-Shaped Island

21. Mars Orbiter: “Dao Valley”

22. Mars Orbiter: “Reull Channels”

23. A Possible Water History on Mars Ancient Modern

24. Earth & Mars Evolved Differently Historic observations –1800’sAstronomers saw Martian clouds –1965Mariner 4 measured very high CO 2 levels Martian cirrus clouds contain both H 2 O & CO 2 ice crystals Atmospheric warming effects –CO 2 on Earth raises temperature ~ 36°C Much terrestrial CO 2 is locked in carbonate rocks –Subduction recycles CO 2 back into Earth’s atmosphere –CO 2 on Mars raises temperature ~ 5°C Mars quickly cooled & solidified because it is so small –No subduction recycling of CO 2 back into Mars’ atmosphere Rainfall dissolved CO 2 & removed it from the atmosphere –Runaway icehouse effect on Mars –Stabilized at present levels

25. The Martian Atmosphere Earlyatmosphere –Probably very similar for Venus, Earth & Mars Abundant volcanic activity during Mars’ early history Abundant H 2 O, CO 2 & SO 2 –Being very small, Mars ran out of heat & magma Once outgassing decreased, the oceans disappeared –Water dissociated into H & O, which escaped Mars’ weak gravity Remaining volcanic gases entered the atmosphere Presentatmosphere –ChemicallyRemarkablysimilar toVenus ~ 95.3% CO 2 & ~ 2.7% N 2 –Expected due to little remaining volcanic outgassing –PhysicallyRemarkablydifferent fromEarth ~ 0.63% as much atmospheric gas as Earth –Expected due to weak gravity & little replenishment

26. Atmospheres of Earth & Mars

27. Viking & Pathfinder Explored Mars Viking spacecraft1976 –Experiments looking for signs of life WaterPeroxides & superperoxides released O 2 NutrientsNo obvious organic waste products HeatedMass spectrometer analyzes gases C 14 addedNone taken up by possible organisms Mars Pathfinder spacecraft4 July 1997 –Sojourner was the small rover on Mars Pathfinder Controlled from Earth with some autonomous functions Discovered an abundance of andesite –Volcanic rockmoderately richin quartz –Rock type first described in South America’s Andes Mountains Surprisingly different from Mars’ southern basalt –Volcanic rockvery poorin quartz –Common in Earth’s ocean basins & the Moon’s maria

28. Mars Viking Lander http://en.wikipedia.org/wiki/File:Sagan_Viking.jpg

29. Mars Pathfinder & Sojourner Rover

30. Mars Exploration Rovers Overall mission –Search for clues to ancient water 2 rovers on opposite sides of Mars Expected operating lifetime of 3 months –Ultimately a search for life Mars Exploration Rover – ASpirit –Landed 4 January 2004 Crater GusevAppears to have been affected by water First intentional grinding of a rock on Mars –Operated until 22 March 2010 Mars Exploration Rover – BOpportunity –Landed 25 January 2004 Landed in Meridiani Planum Came to rest in Eagle Crater, a small impact crater –Still operating as of 22 February 2013

31. Mars Opportunity Before Launch http://en.wikipedia.org/wiki/File:Opportunity_Lander_Petals_PIA04848.jpg

32. Mars Spirit & Opportunity Rovers http://en.wikipedia.org/wiki/File:NASA_Mars_Rover.jpg

33. Mars Opportunity “Blueberries”

34. Mars Opportunity “Meridiani Meteorite”

35. Mars Opportunity “Escher Rock”

36. Mars Opportunity at Endurance Crater

37. Mars Curiosity Rover Mars Science Laboratory (MSL) mission –Spacecraft components Earth–Mars fueled cruise stageSkycraneSkycrane Entry–descent-landing (EDL) system Curiosity rover with instrument package –Soft-landed in Gale Crater on 6 August 2012 Unique “sky crane” landing strategy General mission objectives –Assess Martian climate & geology –Assess favorability of conditions for microbial life –Assess habitability for future human exploration Specific Curiosity objectives –Biological –Geological & geochemical –Planetary process –Surface radiation

38. MSL Cruise Stage Before Launch http://en.wikipedia.org/wiki/File:MSL-Cruise_Stage_Test.jpg

39. Opportunity, Sojourner & Curiosity http://en.wikipedia.org/wiki/File:Mars_Science_Laboratory_mockup_comparison_.jpg

40. Mars’ Atmosphere Is Very Dynamic Diurnal changes –Mars Pathfinder–76°C to –10°C –Daytime heating generates dust devils Weak clear-air tornadoes Pressure dropped as dust devils passed Pathfinder Seasonal changes –Basic patterns~ 20% seasonal pressure changes WinterFrigid temperatures freeze out much CO 2 SpringWarm temperatures thaw out much CO 2 SummerFrigid temperatures freeze out much CO 2 FallWarm temperatures thaw out much CO 2 –Hemispheric differences Northern summerMars is at aphelion –Clear skies warm northern summer much more than expected Southern summerMars is at perihelion –Dust storms cool southern summer much less than expected

41. Martian Dust Devil From Above http://lightsinthedark.files.wordpress.com/2012/03/dustdevil.jpg

42. Mars Global Dust Storm http://science.nasa.gov/media/medialibrary/2001/10/11/ast11oct_2_resources/0131w.jpg

43. Cloud Caps on Martian Volcanoes

44. Cloud Cap On Mount Hood http://fox12weather.files.wordpress.com/2010/09/lenticular-cropped1.jpg

45. Mars Craters & Mounds at Sunset Mars Odyssey (Themis scanner)

46. Mars’ Moons Resemble Asteroids Discovery –Asaph HallFavorable opposition of 1877 Named after chariot horses of the Greek god of war Might be captured asteroids Details –PhobosFear Closest to Mars & largest in size Orbital period of ~ 7 hours 39 minutes –Races from West to East from horizon to horizon in ~ 5.5 hours –Comparable to artificial satellites in low Earth orbit Several times brighter than Venus appears from Earth –DeimosPanic Farthest from Mars & smallest in size Orbital period of ~ 6 days –Creeps from East to West from horizon to horizon in ~ 3.0 days About as bright as Venus appears from Earth

47. The Martian Moons (Asteroids?)

48. Mars data –Diameter only ~ 53% that of Earth –Mass 10.7% & density 72% of Earth –Highly elliptical orbit –Same day & axial tilt as Earth Early Mars observations –Schiaparelli reported seeing canali –Seasonal color change was confusing Seasonal dust storms rearrange dust Retinal fatigue produces cyan color Many spacecraft have visited Mars –Mariner 4, 5 & 7 Two very different hemispheres –Viking landers Looked for signs of life; none found –Mars Pathfinder Included the Sojourner rover –Mars Orbiter Mars’ dynamic atmosphere – Diurnal changes – Seasonal changes Atmospheric pressure varies ~ 20% H 2 O & CO 2 clouds can occur on Mars Mars has two small natural satellites – PhobosFear Fast West-to-East sky crossing – DeimosPanic Slow East-to-West sky crossing Important Concepts