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Exploring Mars: The Search for Life and Its History

Learn about the history of Mars exploration and the ongoing search for past and present life on the planet. Discover the fascinating characteristics of Mars and its atmosphere, as well as the challenges and achievements of current rover missions. Stay updated with the latest news articles relevant to the course.

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Exploring Mars: The Search for Life and Its History

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  1. Announcements • Passing out marks-so-far today with assignments • ½ of available marks now given out • Can always do `bonus assignments' (worth 2 credits) • Find current news article relevent to the course (1 credit) • Briefly describe it and its relevence to the course (1 credit)

  2. The Search: Mars • A Short Biography of Mars • The Planet and its History • The History of Mars Exploration • Past • Current • Future? • The Search for (past) Life on Mars • Viking Experiments • Microbial Fossils

  3. A Portrait of Mars as a Small Planet • Mars • The atmosphere of Mars • How it came to be that way

  4. Mars • Red planet between Earth and Asteroid Belt • Half again as far away from Sun as the Earth is • Expect it to be ~100o F colder than Earth on average • Average too cool for water • Peak temps ~ 70o F (but -130 at night!)

  5. Mars • Near asteroid belt • Likely more collisions than Earth • Large impacts can blow off significant rocky material • Meteorites • As well as gases (atmosphere)

  6. Mars • ~1/2 radius of Earth • ~1/10 mass • ~40% surface gravity • Force of a 1 lb weight less than ½ lb on Mars • Less gravity holding the atmosphere in place

  7. Mars • Too little gravity to be able to hold onto a significant atmosphere • Atmospheric pressure less than 1% of Earth's

  8. Evaporation • What causes evaporation of liquid, and what prevents it?

  9. Evaporation • What causes evaporation of liquid, and what prevents it? • Fastest moving water (say) molecules can escape into atmosphere • Water molecules in atmosphere can collide into water and become part of the liquid • Balance is reached when evaporating water = condensing water

  10. Evaporation • Can change balance: • Little water in atmosphere, evaporation happens faster • (Why feel so sticky on a humid day) • If air pressure is very low, evaporated water molecules can move very far away from pool of water • Fewer around to condense • Faster evaporation

  11. Evaporation • Effect of atmospheric pressure happens on our own planet • Reason for `high-altitude cooking instructions' on some boxes • Higher altitude -> lower air pressure -> evaporation is easier -> lower boiling point

  12. Evaporation • Martian atmospheric pressure < 1% of Earth's • (Earth's atmosphere at 15 miles / 80,000 ft) • Water boiling point is so low that any liquid water evaporates immediately • No free water possible on surface

  13. Evaporation • But water ice DOES exist on Mars: • Polar ice caps • Mostly (on top) dry ice (frozen CO2) • Underneath, visible when CO2 has sublimated, water ice • Quite likely some trapped under surface: `permafrost'

  14. Atmospheric Pressure • Atmospheric pressure is seasonal • Dry ice caps melt • Increase CO2 in atmosphere • Increase atmosphere pressure • Dry ice caps re-freeze • Pressure decreases

  15. The Reasons for the Seasons • Earth's (and Mars') axis is tilted • Earth: 23.5o (Mars: 25.9o) • Tilt stays in same direction as planet orbits Sun

  16. The Reasons for the Seasons Summer • Sun comes in at different angle when planet is at different positions • Summer: • Light most direct • Sun closest to being overhead • Winter • Comes in at angle: • Same amount of light covers larger area • Increased reflection Winter

  17. The Reasons for the Seasons Fall: Cubs win (effective 2003) • Orientation changes over course of year • Another effect: Earth is slightly further from Sun in (Northern Hemisphere) Winter than in Summer • Only ~1% effect (5oF) • Effect of orientation ~16% effect (90oF) Winter: Bears Lose Spring: Bulls Lose

  18. Ecliptic • Because of Earth's tilt, equator (and rotation) do not line up with plane of the solar system • Solar system objects (Sun, Moon, planets) apear to lie along an arc – ecliptic

  19. Ecliptic • Planets are along plane of solar system • Appear on Earth to along an arc • Mars visible these days early at night towards the East, even from Chicago • Bright reddish `star' • Near a bright greenish-yellow `star' (Venus) Starmap for tonight, 9pm

  20. How Mars Came to Be This Way Large Enough for Atmosphere • Distance from Sun makes global liquid water difficult but not impossible • NO ATMOSPHERE • Liquid water quickly evaporates • No greenhouse effect to warm planet, regulate temp. • No ozone to protect from UV Not Large Enough for Atmosphere

  21. The History of Martian Exploration • Past explorations • Current Rover Missions • Future Plans

  22. Exploration of Mars Today • So many recent missions to Mars that it's becoming almost anticlimatic • News filled with discoveries from current rovers • Still very difficult: • Success rate low! • Scientists can't go there at whim yet

  23. Observations of Mars from Earth • Early telescope observations: • `observations' of canals • Improved telescopes showed this not to be the case • Later, radio observations • Surface temperature • Crude radar maps of surface

  24. 1960-2: Korabl (`Marsnik') • Attempted Russian Probes • 4 attempted flybys, 1 attempted landing • Most barely made it past Earth orbit, one was lost between Earth and Mars

  25. 1964: Mariner, Zond • Mariner 3, 4 (USA): attempted flyby • Mariner 3: Couldn't make it to Mars • Mariner 4: First flyby, close up pictures • Zond 2 (USSR): Russian flyby, descent • Lost on its way to Mars

  26. 1969: Mariner, Mars 1969 • Mariner 6,7: Identical flyby craft • Mariner 4: First flyby, close up pictures • Mars 1969A/B: Russian flyby, descent • Didn't survive takeoff

  27. 1971: Mariner, Mars 2/3: Orbiters • Mars 2/3 (USSR): First orbiter of another world • Measured temps, magnetic fields • Sent probe, 1 crashed too fast, other survived 20 hours Mariner 8 didn't make it • Mariner 9: Orbited, obscured by storms • First close-up views of moons of Mars

  28. 1973: Mars 4/5/6/7 (USSR) • Mars 4: Brakes didn't work; flew by instead of orbited • Mars 5: Successful Orbit, pictures • Mars 6: Descent, sent data from atmosphere before shutting down, but data garbled • Mars 7: Missed Mars entirely

  29. 1975: Viking 1,2 (USA) • Identical Orbiter + lander • Orbiters searched for safe landing places • Extensive weather measurements, chemistry/biology experiments • Sent several thousand images, data

  30. 1988: Phobos 1,2 (USSR) • Lost due to human error (Phobos 1), computer malfunction (Phobos 2)

  31. 1988-1992 • 1988: Phobos 1, 2 (USSR) • Lost due to human error (Phobos 1), computer malfunction (Phobos 2) • 1992: Mars Observer (USA) • All contact lost 3 days from Mars

  32. Very Recent Mars Missions • 1996: • Mars 96 (USSR): Didn't successfully leave Earth • Mars Global Surveyor (USA) • Looking for places to send Pathfinder • Still sending back data • Mars Pathfinder • Probe with some sensors • Test of new technologies, techniques

  33. 1998: Less Successful • Nozomi (Japan) • Navigation problems • Could not reach Mars at expected time • Unable to orbit Mars • Mars Climate Orbiter (USA) • Crashed into Mars after mistake in converting units in probe computer programming

  34. 1998-9: Less Successful • Nozomi (Japan) • Navigation problems • Could not reach Mars at expected time • Unable to orbit Mars • Mars Climate Orbiter (USA) • Crashed into Mars after mistake in converting units in probe computer programming • Mars Polar Lander (USA) • Signal lost near Mars: Navigation errors?

  35. 2001: Mars Odyssey(NASA) • Orbiter • Build global map of telements, minerals on the Mars surface • Determine the abundance of hydrogen in subsurface. -> hidden deposits of water ice? • Structure of the Martian surface. • Radiation environment between the Earth and Mars and in low Mars orbit (radiation-related risk to human exploration) • Communication relay Spirit/Opportunity/Beagle

  36. 2001: Mars Express(Europe) • Orbiter + Lander/Rover (Beagle) • Beagle lost • Image globe in 3D • Build accurate picture of meteorology/climage • Communications Relay

  37. 2003: Spirit, Opportunity(USA) • Search for/study many types of rocks and soils that might hold clues to past water activity. • Maps showing the locations of different kinds of rocks and soils around the landing sites. • What forces have shaped the landscape • Search for minerals that contain water/formed in water. • Identify minerals, how made • Clues to what environment was like in past

  38. The Search for Life on Mars • Pictures of surface • Viking biology experiments • Meteoritic `fossils' • Future?

  39. Venus • Closest to Earth • ¾ as far away from Sun as Earth is • Very similar to Earth's size, density • Covered by thick, opaque clouds

  40. Reading for Next Class (Apr 16) • Chapter 15: The Outer Solar Systen • History of Outer Solar System Exploration • The Nature of Gas Giants • Atmosphere • Chemistry • The Moons of Jupiter, Saturn, Uranus, Neptune • Chapter 16: How Unique is Earth? • Necessary Resources • On Having a Large Moon • Staying alive by accident

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