Unit Three: Investigating Planets
Doing Science

1. Surface Features on Other Worlds: Like or Unlike?

Introduction:
In the last forty years or so, images of several other planet and moon surfaces have been sent to Earth with detailed views of many different types of features. Most of these "alien" features are similar to features on Earth, though different in size or details of shape. Since surface features on any planet are shaped by the physical processes such as wind, condensation and flow of liquids, impacts, and melting or freezing of rocks and ice. Similarities and differences between surface features on Earth and other planets and moons provide clues to how surface conditions on these worlds are presently, or have changed over time.

Directions:
Choose one of the types of surface features listed below. Collect 8 � 10 satellite and/or ground images of each feature on both Earth and Mars.

1. Dunes: formed by flowing air or water; often found in desert areas like the Namib Desert in SW Africa or in the American West.
2. Sinuous Channels: usually formed by flowing liquids; their detailed shapes provide information about precipitation or liquids following under ground;
3. Layered Rocks: usually formed by flowing air or liquid, but different layers indicate changes in surface conditions. A good place to look for layers is in canyon walls, like the Canyon on Earth or Valles Marineris on Mars.

Some good sources for Earth images are:

• Lunar & Planetary Institute slide sets: http://www.lpi.usra.edu/publications/slidesets/ Includes a few hundred selected images from the astronaut photograph collection with explanatory captions. This is a good place to start in learning to recognize classes of features from space.
• Earth from Space: http://earth.jsc.nasa.gov/sseop/efs/ About 1000 outstanding images of Earth from the Space Shuttle or International Space Station, sorted several different ways, including feature type and location.
• Google Maps http://maps.google.com/ Use the "Satellite" setting. Works on all computers.
• Google Earth: http://earth.google.com/ Provides 3-D views, but you must download a software package that doesn't run on all types of computers.

Some good sources for Mars images are:

• Google Mars: http://www.google.com/mars/ Provides global views of topography, visible and infrared satellite images of the red planet.
• HiRISE: http://hirise.lpl.arizona.edu/ Many spectacular recent satellite images.
• Mars Orbiter: http://www.msss.com/ Home site of the most successful of Mars imaging mission. The site has an enormous archive of satellite images of Mars.
• NASA's Mars Exploration Program http://marsprogram.jpl.nasa.gov/overview/ Rover images of the surface of Mars. Good collections of images are found under Mars Images under Multimedia and Press Releases under Mars for Press.

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Your Challenge:


1. Collect your images into a hardcopy or PowerPoint presentation that compares the similarities of the features on Earth and Mars; e.g., the Grand Canyon vs. Valles Marineris, or the Mississippi River vs. Kasai Valles. Provide descriptions of differences and similarities between features on the two planets, including measurements of characteristic sizes of the features.
2. Discuss what the similarities and differences between features on Earth and Mars tells us about conditions on each planet—precipitation, winds, or sequences of geological events.
3. For an additional challenge, do a comparative analysis of another feature type between Earth and another object, like Venus. Good places to start are the U.S. Geological Survey's Map a Planet web site: http://pdsmaps.wr.usgs.gov/ and the National Space Science Data Center: http://nssdc.gsfc.nasa.gov/.