NASA - National Aeronautics and Space Administration

Who are NASA's Earth and Space Science Explorers?

The middle school students who track weather to study its effect on bursting tree buds. And the scientist studying black holes in distant galaxies. But also the teacher whose class shares Earth science data with students around the world. And the engineer who designs robotic instruments to probe hard-to-reach planets. All of these people are Earth Explorers, Space Science Explorers or both. The Earth Explorers and Space Science Explorers series features NASA explorers, young and old, with many backgrounds and interests.

Nominate an Earth or Space Science Explorer!

Tell us about the Earth Explorers and Space Science Explorers you know. We're looking for students, teachers, scientists and others who have a connection to NASA, whether they work for the agency or are involved in a NASA-supported mission or program. Send your nominations to Dan Stillman: dan_stillman@strategies.org.

Phil Christensen stands in front of a Delta rocket. The picture was taken three days before the rocket carried an instrument called THEMIS to space. Image Credit: Phil Christensen

Rocks can be fun to collect. They come in many shapes and sizes. Some are gray and some are very colorful. They can be very smooth or very rough. All rocks are made of minerals. The color and feel of a rock depend on the minerals it contains.

Did you know that clues about the past are hidden in rocks?

Some rocks are millions of years old. Over time, wind and water can wear down a rock. Earthquakes and volcanoes also change rocks. The minerals in a rock can tell about its history. They can also tell about the history of the entire Earth.

Phil Christensen has a large collection of rocks. He has big rocks and small rocks. He has bumpy rocks and shiny rocks. In all, he has more than 8,000 rocks. That's right -- 8,000!

How did he get so many rocks?

Phil has liked rocks since he was a kid. He's also always wanted to know more about Mars. Mars is a rocky planet much like Earth. When he was young, Phil spent hours looking at Mars through his telescope.

Now, Phil is a scientist for NASA. Scientists are always asking questions. One question Phil has is, "Are rocks on Earth like rocks on Mars?" The first step to finding an answer was to collect rocks from around the world.

But how would he do it? Visiting all the places he would need to go would take forever. Instead of collecting the rocks himself, Phil thought of a neat idea. He would ask kids everywhere to send him rocks.

This rock is from Australia. It is one of more than 8,000 rocks sent in by students to the Rock Around the World project. Image Credit: Arizona State University

That idea was the start of the Rock Around the World project. Students have sent in more than 8,000 rocks. Phil and other scientists study every rock. They use special tools to discover what minerals are in each one.

Studying rocks from Earth is the easier part of Phil's project. Learning about rocks on Mars is more difficult. To do this, Phil helped create a special camera that was launched into space. The camera is called THEMIS. It circles Mars and takes pictures of rocks there.

The pictures can be used to figure out what kinds of minerals are in Martian rocks. They also give clues about whether there is water on Mars. Scientists learn a lot by comparing rocks from Earth and Mars. They learn how Earth and Mars are different, but they learn how the planets are alike, too.

Mars is the planet most like Earth. Humans may even go there someday. Studying Mars "can tell us a lot about the planet ... and what humans have to be prepared for when they get there," Phil said.


Related Resources
Rock Around the World  ⇒
The Space Place: Blast Off on Mars Adventure!  ⇒
Previous Space Science Explorers Articles
Previous Earth Explorers Articles

Dan Stillman, Institute for Global Environmental Strategies