PTYS 214 – Spring 2011  Homework #8 – DUE in classToday  Grades are updated on D2L (please check)  Class website: /  Useful Reading: class website  “Reading Material” Announcements

HW #7  Total Students: 27  Class Average: 6.93  Low: 3  High: 10 Homework are worth 30% of the grade  Total Students: 15  Class Average: 3.2  Low: 2  High: 4 Quiz #7 Quizzes are worth 20% of the grade

Extra Credit Presentation Richard-Jacob Corona Cristina Retamoza

Mineralogical Evidence: Martian Meteorites  Pieces of rocks ejected from Mars after impact events and reaching Earth’s surface  Of over 30,000 meteorites found on Earth, only 34 have been identified as Martian meteorites  They are also known as SNC, from the names of the most representative types (Shergotty, Nakhla, Chassigny) Nakhla (1911) Chassigny (1815)

How do we know that some meteorites are from Mars?  Age separates them from other meteorites - Almost all Martian meteorites are much younger ( Myr) than most meteorites, and have a composition similar to terrestrial basalts  Oxygen isotopes separates them from Earth’s rocks - values of 16 O, 17 O, and 18 O are distinct from terrestrial rocks and group all 34 Martian meteorites together  The isotopic composition of gases trapped in the meteorites is almost identical to the Martian atmosphere (comparison with Viking measurements)

Comparison of Mars atmosphere measured from Viking to trapped gases in EETA79001 (Shergottite): Values are the same! The impact that ejected the meteorites causes some melting of the rock The melt cooled very rapidly and formed a glass that trapped atmospheric gases Atmospheric gases

Evidence of Water in Martian Meteorites  Carbonate minerals - Liquid water flows through fractures in rocks and dissolved CO 2 can be precipitated  Hydrated minerals have martian D/H (deuterium to hydrogen ratio) Electron Microscope image of clay and carbonate (siderite) vein in meteorite Lafayette ol: olivine

Beyond Water: Evidence of life?  ALH84001 is a Martian meteorite that became famous because it appeared to contain structures that were considered to be fossilized remains of bacteria-like lifeforms  More in the next lecture…

Images From Mission Animation by Dan Maas Challenges of Planetary Exploration: Mission Phases Launch & Cruise Entry, Descent, Landing Egress, Surface Operations

 Need powerful rockets and a lot of fuel to push the spacecraft away from Earth’s gravity  Must launch when the geometry is right for encountering the planetary object! Challenge 1: Launch

Navigators have to aim for a moving target: where Mars is going to be, not where it is at launch Challenge 2: Traveling 250 million miles through space

Too close to Mars and a spacecraft will go into its atmosphere and burn up… Too far away and it will go right by Mars and never get captured by its gravity field! Orbit Insertion Challenge 3: The spacecraft needs to be precisely on target

Entry Angle: 11º Any steeper and you get to the ground too fast! Any shallower and you skip back into space! ~ 100  20 km! Challenge 4: Entering the atmosphere is a nail-biting time! ( Landers )

The Challenge for all Mars landers: Take three zeros off the entry velocity in less than 6 minutes! Challenge 5: Final Descent ( Landers ) Intense heat! ( need for a heat shield ) Parachute for safe landing Navigation system to avoid surface hazards

We never know if the mission will succeed… The international community has sent: ~30 orbiters 16 landers 2 probes with the goal of understanding Mars 52% of the time, Mars has won! …but we are getting better! 20 24

s 1970s 1990s Canals? Mariner 4 Moonlike with water? Mariner 9 Viking Mars Global Surveyor Odyssey Fuzzy Telescope View Giant canyons, volcanoes, wind, ancient water, & impact craters Dynamic landscapes suggesting water and climate cycles No longer Lunar Subsurface water & minerals Here is what we learned so far: MER More water HiRISE Resolves details as small as 2 feet! 6 m crater

Phoenix Scout Mission Principal Investigator is Prof. Peter Smith, University of Arizona First mission to explore the Arctic region of Mars at ground level It is NASA’s first Scout Mission (missions designed to be relatively low-cost and innovative complements to NASA’s Mars Exploration Program – Phoenix total cost is  $420 Million)

Evidence of Ice In line with NASA’s motto for Mars: “Follow the water”

HiRISE views of landing site On Earth they develop by seasonal or episodic melting and freezing of permafrost Region of contraction-crack polygons (from melt-freeze cycles) Devon Island, Arctic Canada

Phoenix Instruments “Eyes”: Surface Stereo Imager (SSI) Robotic Arm Robotic Arm Camera Thermal and Evolved Gas Analyzer (TEGA) Microscopy, Electrochemistry, and Conductivity Analyzer (MECA)

Phoenix Instruments Meteorological Station Dust increase Provides information about the size and location of atmospheric particles

Phoenix Findings General –confirmed the hypothesis based on orbital data that there is shallow subsurface water ice on Mars (1-10 cm in the Martian arctic) June 15June 19 Ice under the spacecraft…

Phoenix findings Soil Properties –Very sticky –Very cloddy in some areas Possibly cemented by carbonates and/or other salts in presence of small amounts of water

Phoenix Findings Chemistry –Unexpected: perchlorate (ClO 4 - ) in the Martian soil (perchlorate is harmful to humans, but is used as a source of energy by some microbes) –Carbonates: high probability of calcite, possibly other carbonates as well  implications for past climate and liquid water –Neutral pH, around 7.7 (similar to values found by Viking)

Phoenix findings Weather (MET and SSI) over ~150 days –Snow, frost formation and fog in the late summer –Water ice clouds and dust storms –Dust devils in Martian arctic October 13, 2008: Dust devils passing 1 to 2 km from Phoenix

Changing Weather October 7, 2008: The weather begins to degrade at the Phoenix landing site: storm activity increases with potential for snowfall

Autumn Frost Frost accumulates on the Martian surface in the Fall June 26, 2008 October 20, 2008 As the Sun sets over the Martian Arctic, temperatures plunge to overnight lows of -89°C (-128°F) and daytime highs in the -46° C (-50°F) Phoenix last communication : November 2, 2008

Next Planned Mission: MSL (Mars Science Laboratory) Long duration rover, much larger than Spirit and Opportunity currently on Mars Launch: fall 2011 Goal: Assess whether Mars ever was, or is still today, an environment able to support microbial life (that is, to determine Mars’ habitability) Challenge: - To land a very large and heavy rover on the surface of Mars - To execute a very precise landing - To demonstrate long-range mobility on the surface (5-10 km, or 3 to 12 mi). MER MSL Pathfinder

Picking a Landing Site 1.The chosen site should be the most likely place where life might have had a chance 2.Engineers must be sure the rover can safely reach the site and drive within it

Potential Landing sites for MSL

The Search for Life on Mars Viking Mission, 1976: First successful landing of a spacecraft on the surface of another planet, and execution of biology experiments Two orbiters + two landers Cryse Basin Elysiu m Mons Hellas Chryse Planitia Utopia Planitia Olympus Mons Vallis Marineris