Mars Astronomy 311 Professor Lee Carkner Lecture 14
Mars -- The God of War
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
Mars Facts Size: ~1/2 Earth size Orbit: 1.5 AU Description:
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
Spacecraft to Mars Mariner 4 was the first spacecraft to visit Mars in 1964 Current missions: Mars Express (2003, orbiter) Spirit and Opportunity (2003, rover)
Pathfinder Rover Sojourner
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
Tharsis Rise
Olympus Mons
Valles Marineris
Cratering on Mars
Mars Topological Map
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
Standing on Mars
Mars’s Atmosphere Composition: 95% CO 2, 3% N 2, trace amounts of water vapor and oxygen Pressure: atmospheres Early Mars may have had a thicker CO 2 and H 2 O atmosphere
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
Frost on Mars
Polar Ice Cap
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)
Dried-up River Bed
Past Water Erosion on Mars
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
Viking’s Soil Scoop
Fossil Life in Martian Meteorite?
Cydonia “Face” on Mars
Traits of Psuedoscience Certainty Avoidance of Occam’s Razor Paranoia
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
The Moons of Mars Mars has 2 moons, Phobos (“fear”) and Deimos (“panic”) They are small and in tight orbits Phobos: orbital radius 6000 km Deimos: orbital radius km
Phobos and Deimos
Continuing Mars Exploration Next mission is the high resolution Mars Reconnaissance Orbiter Other future missions to be determined: Sample return?
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
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
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
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