Learning Objectives. they differ in density, composition, atmosphere, surface age, size, geological activity, magnetic field?

Transcription

1 The Red Planet

2 Learning Objectives! Contrast the Terrestrial Planets and the Moon. Do they differ in density, composition, atmosphere, surface age, size, geological activity, magnetic field?! Why is Mars red? Why are Phobos and Deimos strange shapes? What is Olympus Mons?! Earth and Mars were likely once similar. What quality of Mars made it different to the Earth by the present? (This also made Olympus Mons very high)! Was there once water on Mars? Was it liquid water? Is there now water on Mars? Is it liquid water?! What are Spirit, Opportunity and Curiosity?

3 Mars Facts! Mars has two moons, Phobos and Deimos Radius 0.53 Earth Surface gravity 0.38 Earth Mass 0.11 Earth Distance from Sun 1.5 AU Eccentricity 0.09 Tilt 25 Year 687 Earth days Solar day 24 hours 39 mins

4 The Canals of Mars! Mars color suggested a desert world! Canals were thought to irrigate the desert with water from Mars ice caps! No doubt the Martians would want to conquer the Earth for its abundant resources!!!! Spawned many sci-fi stories...but, of course the canals are not real they were a mistranslation of the Italian word canali

5 The Martian Atmosphere! 96.0% CO 2, 1.9% Ar, 1.9% N 2, 0.1% O 2! Composition similar to Venus! Also a little water vapor (very little)! Unlike Venus, Mars atmosphere is thin! Less than 1% of the Earth s! Mars is too small! Mars doesn t have sufficient gravity to hold even a thick atmosphere

6 Magnetic Field! Mars magnetic field is very weak and patchy!mars (currently) has no global magnetic field! Like Earth, Mars has a solid iron core! About half of the planet s radius in size

7 Temperatures on Mars! Daily temperature variations, as on Earth! Coldest at sunrise! Warmest a few hours after noon! But colder (on average)! It s farther from the Sun! A thin atmosphere so CO 2 only raises temperature by about 5 K! Temperatures can reach -143 o C (-225 o F) in the polar regions in the winter and 35 o C (95 o F) in the equatorial regions in the summer

8 The Martian Surface! Mars is a desert! Iron oxide (rust) in the soil gives reddish color View of Twin Peaks from Mars Pathfinder

9 The Geology of Mars Phoenix (2008) Viking 2 (1976) Viking 1 (1976) Mars (1996) Pathfinder Opportunity (2004) Curiosity (2012) Spirit (2004)

10 Olympus Mons! The largest mountain in the Solar System, rising 26 km high! A shield volcano (high, sloping sides), like Hawaii! Its caldera is 90 km across, its base is ~550 km across! Extends almost to the top of the Martian atmosphere)

11 Phobos & Deimos! Mars two small moons Phobos is ~22 km across! Deimos is ~12 km across!! Strange, irregular shapes! Kind of like potatoes

12 Mars Past! Early in Mars history it was more Earth-like! Geologically active! Volcanoes created thick CO2, N2 atmosphere, which escaped over time! Thick CO2: Greenhouse effect made it warm enough for liquid water! Oceans? Rivers? Glaciers by the poles?! But Mars is far smaller than the Earth, so has changed substantially

13 What Happened?! Mars is far smaller than the Earth! so cooled internally much faster than the Earth! Mars may have once had rudimentary plate tectonics (if so Mars only had a few plates), which shut down! Volcanoes sat, static, over hotspots and grew to immense sizes! Volcanic activity slowed as the interior cooled! The atmosphere leaked away and escaped! The planet froze

14 Life on Mars?! Although current life hasn t been discovered on Mars, there is evidence that Martian soil could support or have supported life! There is even very weak evidence for organic molecules in the Martian soil! So, could there have been life in the past?! Before Mars froze?! On Earth, the abundance of liquid water is linked to the abundance of life...

15 Water on Mars? Yes!! There is still water on Mars! Polar ice caps are mostly water! There is some water vapor in the air! Rovers directly found water locked in the soil! % of the Martian soil is water! Rovers directly detected water in the soil at ~1-2 feet depth! Rovers directly detected brine (salt-water) on Martian slopes which freezes in the winter and flows in the summer

16 Water on Mars? Yes!! In 2017, the HiRISE camera on the Mars Reconnaissance Orbiter detected water ice sheets in scarps at 8 locations on Mars! These sheets are 100s of meters thick! They are covered by only a few meters of soil! More than 5 million cubic kilometers of ice has now been detected at or near the surface of Mars!

17 Spirit Rover! Designed to survive for 90 days! Survived 2269 days in total

18 Opportunity Rover Sol is short for a solar day on Mars Sol 3968! Designed to survive for 90 days! Survived ~ 5100 days so far

19 Curiosity Rover! Survived ~2000 days so far

20 Manned Mars Exploration! Manned missions to Mars are often discussed, with around 60 proposed in the last 50 years!! Such missions always seem to be ~10-15 years in the future! But it is not unreasonable to think one could happen in our lifetimes

21 Next Time The Fathers of the Gods