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21st CENTURY EXPLORER
Are we there yet?
Why do astronauts eat tortillas instead of bread?
How would your body change in space?
How can we travel faster in space?
What will replace the Space Shuttle?
Why do robots travel places before people?
Why return to the Moon before going to Mars?
Why do we want to study and travel to Mars?
Where would a space explorer find water and oxygen?
What would you find on the Moon’s surface?
What would you hear in a weather report from Mars?
How will your imagination help you become an explorer?
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Why do we want to study and travel to Mars?

Subject Matter Expert: John Connolly and Chuck Lloyd

Mars has always made us wonder. Why is it red? Was there ever water on its surface? Will we find life there? Answers to these questions and others will come from studying and traveling to Mars.

Mars is called the “red planet” for a very good reason -- its surface looks red to our eyes. The soil is rusty, containing iron, the same chemical as rusty metal. Long ago, parts of Mars may have been covered in blue – blue oceans. Robot landers and other space probes show evidence that parts of Mars were once covered with liquid water.

Since 1997, NASA’s Mars Global Surveyor spacecraft has taken pictures of the Martian surface. Parts of its surface look like a flash flood has washed over the land, similar to flooding seen in the western United States. Some pictures from its high resolution cameras seem to show signs of past major flooding along Mars’s equator.

In 2004, NASA landed two robot rovers called Spirit and Opportunity on Mars. These rovers investigated rocks and soil and took pictures of features that seem to prove Mars was very wet in the past.

Water already has been found on Mars in the form of ice in the polar ice caps. The Martian ice cap in the north is about 4 kilometers (2.5 miles) thick. Another place on Mars that probably contains a lot of frozen water is in the permafrost that is buried just below the surface. The Martian permafrost may be several kilometers thick all over the globe and may be as much as half ice.

Based on what we have observed so far, Mars today is a frozen desert. It's too cold for liquid water to exist on its surface and too cold to rain. The planet's atmosphere is also too thin to permit any significant amount of snowfall. You cannot breathe on Mars because its atmosphere contains so little oxygen.

Finding evidence that helps prove Mars had liquid water in the past supports the ideas and beliefs that life could have existed on Mars. Many questions about the history of water on Mars are likely to remain unanswered until samples are returned from the red planet for examination on Earth.

In 1976, NASA landed two Viking spacecraft on Mars. Viking tested the soil to see whether any life was present. Using a small scoop, Viking dug into the Martian soil. It picked up small samples, dropped them into a bin, and looked for signs of life.

What kind of life did the scientists expect to see? They based their experiments on the idea that life on Mars would be very simple, something like the bacteria found on Earth. They looked to see if anything in the Martian soil seemed to be “eating” organic materials or giving off gases like carbon dioxide.

What did the scientists discover? There seemed to be some interesting chemical activity in the soil but no clear proof of any living things.

We can find more clues about Mars by studying meteorites. We have discovered about a dozen meteorites on Earth that are thought to be from Mars. All are igneous rocks that formed from molten magma. They have a similar form of oxygen and higher concentrations of iron and water than other meteorites. Gas bubbles trapped in one meteorite match the current Martian atmosphere as measured by the Viking Landers.

And, they contain some evidence that points to possible life. High-resolution scanning electron microscopes show the presence of tiny “ovoids” that may be the fossil remains of very tiny bacteria. If so, they are 100 times smaller than any bacteria microfossils found on Earth. Perhaps there was once simple bacterial life on Mars.

Mars is almost certain to have been warmer and wetter in its distant past, so the existence of simple life has been a tantalizing possibility for some time. The real search may be just beginning.

Future NASA missions will land on Mars, collect rock and soil samples, and return them to Earth. We hope to learn much more about the red planet and, perhaps one day, send people there to explore firsthand

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The following National Education Standards are addressed in this educational package.

Science (NSTA/NRC)
Health (AAHPERD)
Geography (NCGE)
Mathematics (NCTM)
Language Arts (NCTE)

For an alignment see the Educator Section.