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Major Features
Major Features
Although Mars is only about half the size of Earth, it is home to the largest volcano, biggest canyon and largest dust storms in the solar system.
You will need access to Google Earth (download). Watch the video to see how to access Mars from Google Earth. Fly to Mars and take the tour by Ira Flatow. Note that the MOLA image is a topographical map that displays height as colour.
Because there is no sea-level on Mars, height is displayed from -8 to +12 kilometers.
Because there is no sea-level on Mars, height is displayed from -8 to +12 kilometers.
TASK: Locate the highest and lowest points on Mars and calculate the difference in height. Locate Olympus Mons and Valles Marineris. How big (height and width/length) are both features? Briefly explain why Olympus Mons is so large. Briefly explain what forces may have created Valles Marineris (hint, in the Ira Flatow tour fault lines are shown on the floor of the valley).
Using either Mars in Google Earth, or the (very) large MOLA map.
Notice that the northern hemisphere is several kilometeres lower than the southern hemisphere. Scientists are still debating whether the difference between the hemispheres was caused by an large asteroid impact, or the lava-covered floor of an ocean.
Zoom in and notice the differences in terrain between the two hemispheres. The southern hemisphere is heavily pocked marked with impact craters, while the northern hemisphere has few craters, which implies that the southern hemisphere is much older than the northern hemisphere. (see image)
Take a close up look at craters in the two hemispheres. Notice the different shapes of the ejecta pattern. The northern hemisphere craters look like they were formed from mud, and are known as 'splosh' craters.
Northern Hemisphere Craters
Northern Hemisphere Craters
Southern Hemisphere Craters
Southern Hemisphere Craters
Water on Mars
Water on Mars
The first hint that water once flowed on the surface of Mars was revealed by satellite photographs - images of what looked like dried up river systems.
New satellites sent back images of what looked like ancient deltas. Deltas on Earth are created when rivers reach standing bodies of water, and as the water slows down the river deposits sediment at the shoreline in a fan-shaped delta.
Rovers on Mars
Rovers on Mars
The Mars Exploration Rovers, Opportunity and Spirit, discovered sulphates in the soil, which only form in the presence of water. (See image below - white 'soil' was churned up by the rover's wheels). And 'blueberries' - small balls of the mineral hematite, which form when water interacts with the chemicals in rocks.
The Mars Polar Lander, Phoenix, discovered ice just below the surface near the north pole, and carbonates in the soil, another mineral that only forms or breaks down in the presence of water.
A few weeks after the Curiosity rover touched down in Gale crater on Mars, it sent back images of an ancient stream bed and conglomerate rocks.
Images above left to right: Curiosity Rover, Gravel stream bed, conglomerate rocks on Mars compared to Earth. Note that the pebbles are rounded, and are too large to have been transported by wind - evidence of a long gone fast flowing stream.
Image at left is also taken by Curiosity, looking towards the mound in the middle of the crater. Note the horizontal layers, which implies water, and sedimentary process have been at work.
While the surface water on Mars has long gone, frozen water still exists beneath the dusty surface, and on Earth, where there's water ... there's life. Could life have ever evolved on Mars? Does life still exist on Mars?
TASK: Describe three geological features that would indicate the presence of water, and explain why.
Next we'll look at the search for life on Mars.
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