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Mars Revisited On Assignment

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Mars Revisited
Step into the world of writers and photographers as they tell you about the best, worst, and quirkiest places and adventures they encountered in the field.

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Mars Exploration

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Photograph by Timothy Glotch, ASU; NASA/JPL    
By Oliver Morton

The so-called red planet is ages—make that ice ages—removed from the inert wasteland scientists once thought. Now landers are closing in to probe the big question: Could there be liquid water, and with it signs of life?

Get a taste of what awaits you in print from this compelling excerpt.

Geologists have long been fascinated by Mars's distant past. Now they're getting even more excited by the mysterious processes shaping its present—thanks in large part to the planet's apparent iciness. Martian ice is not a novelty in itself; for years geologists have expected to find it frozen into the soil at mid and high latitudes.The excitement comes from a growing suspicion that the ice doesn't just sit there but has a dynamic role to play. That it moves from place to place around the globe. That it reshapes the textures of the surface. And that it may sometimes produce fleeting traces of liquid water.

If you could get to Mars, you could see for yourself. But for now the closest anything or anyone from Earth can get to Mars is when one of the growing fleet of spacecraft orbiting the planet passes some 400 kilometers (250 miles) overhead.
The latest generation of orbiters is revolutionizing the study of Mars from space, discerning ever smaller surface features and analyzing terrain with increasingly sophisticated tools. Cameras on NASA's Mars Global Surveyor (MGS) and Mars Odyssey watch the planet day and night in visible and infrared light. Other sensors on Odyssey detect gamma rays and neutrons radiated from the minerals below, revealing to those versed in nuclear physics the abundance of different elements, such as hydrogen and iron. 

When Mars Express reaches the planet, it will add yet more instruments to those already aloft, including a multispectral imaging spectrometer that can identify minerals using visible and infrared wavelengths, and a radar that may detect ice and liquid water below the surface.
As they beam a continuous stream of fresh data to Earth, the orbiters evoke a thrilling new picture of Mars—and a genuinely puzzling one: While searching for answers to old mysteries, the orbiters are bombarding us with new ones. Hugh Kieffer, a Mars veteran at the United States Geological Survey (USGS) who has been studying the planet for almost four decades, tells his younger colleagues they are in a "period of maximum confusion." New data—whole new types of data—are accumulating faster than researchers can make sense of them. The result is something like an optical illusion. Contradictory images of Mars seem to flicker in and out of focus in the mind's eye.

"Although Mars is supposed to be the god of war, the planet is much more like a prima donna," says Nathalie Cabrol, a planetary geologist at NASA's Ames Research Center. "When you think you have it right, Mars always has a surprise."

The man whose imagination first took him to the crater rim on the edge of the butterscotch plain is Philip Christensen, a geology professor at Arizona State University in Tempe. Christensen leads the team responsible for designing and building the Thermal Emission Imaging System (THEMIS), the instrument on board Odyssey that generates pictures of the surface in visible and infrared wavelengths. When THEMIS sent back its picture of that crater and its strange lining in the early summer of 2002, Christensen had what every scientist yearns for—a eureka moment. For the first time he thought he could see how Mars's mysterious gullies might form.

Get the whole story in the pages of National Geographic magazine.

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Sights & Sounds
Experience the changing face of the red planet in this multimedia exclusive, "A Mars Never Dreamed Of."

Interactive Art
Explore thousands of miles of the solar systems' largest canyon system in minute detail.
Watch an animation of the weather conditions that scientists say support current evidence of liquid water on Mars.
RealPlayer  WinMedia

Watch the virtual entry, descent, and landing of the Beagle 2 lander, one of the latest probes sent out to collect surface samples and search for life on Mars.
RealPlayer  WinMedia

All rights reserved Beagle 2


Philip Christensen, a geology professor at Arizona State University at Tempe, walks magazine staff through the layout of Mars images appearing in the print article.

Spread out the icy landscape of Mars's southern hemisphere as wallpaper for your desktop.
Is there life in the ancient ice of Mars?  Vote then join the forum.
Yes      No

More to Explore

In More to Explore the National Geographic magazine team shares some of its best sources and other information. Special thanks to the Research Division.

Did You Know?
Athletes on Mars
A little spring skiing, anyone?  Picture yourself in a temperate zone of Mars's southern hemisphere, standing on the rim of a crater in Dao Vallis. Sloping away from you is a kilometers-long icy glacier. It's not too steep, so you think you can manage it.  There are a few centimeters of very fine dust on the surface, but it's just like baby powder and you should be able to schuss through it with no trouble. 
You take off, determined to negotiate down the slick, hard ice in as straight a line as possible. You look funny in your bulky, pressurized space suit, but in the end it will cushion the big bounces you'll endure if you fall going at high speed in Mars's low gravity.  And it will help with the cold:  Even at noon it's only about minus 22°F(-30°C). Not too windy though, and the sun is shining and morning clouds have dissipated.  

You're doing fine; it's a nice, long run. What looked like gentle moguls from the top of the glacier suddenly look a little dangerous, though. You're going fast on this steep part of the slope; the ridges ahead are meters high, and there are a lot of them. Time to rethink the adventure. You dig in, turn, and come to a rather inelegant stop, but you're in better shape than if you'd hit those ridges. Now, where's the ski lift back up?

Disclaimer: We don't know that remnants of an ice age on Mars still exist as isolated glaciers, dusty snowpacks, or near-surface ground ice, but observations are convincing planetary scientists that such features are probably shaping the surface of Mars today. (See "Mars: Planet Ice" in this month's magazine and particularly the images on pages 10-15.) We are many decades away from putting humans on Mars, and when we do, it's unlikely they will do any schussing.

—Barbara W. McConnell
Did You Know?

Related Links
Mars Missions
Find a listing of all NASA missions: past, current, and in development, with links to specific mission sites.
Infrared Images
Explore the main site for the Thermal Emission Imaging System (onboard Mars Odyssey) data, including a very navigable archive of images.
Mars Orbiter Camera
Get images, captions, and additional information about the camera on Mars Global Surveyor, which has been mapping Mars since 1999.
Mars Express
The European Space Agency site focuses on the details of the present mission to Mars and includes background information and news updates.
Though long delayed in its arrival at Mars, the Japanese mission plans to study the planet's atmosphere. Details here.


Carr, Michael H.  Water on Mars. Oxford University Press, 1996.
Christensen, Philip R., et al. "Morphology and Composition of the Surface of Mars: Mars 
Odyssey THEMIS Results," Science (300), 2056-61.
Dick, Steven J. The Biological Universe. Cambridge University Press, 1996.
Kieffer, H. H., et al. Mars. University of Arizona Press, 1992.

Various. Journal of Geophysical Research (106), 23,289-23,945.
Various. Nature (412), 209-53.
Wilford, John Noble. Mars Beckons.  Alfred A. Knopf, 1990.


NGS Resources
Beatty, J. Kelly. Exploring the Solar System: Other Worlds. National Geographic Books, 2001.
Sawyer, Kathy. "
A Mars Never Dreamed Of," National Geographic (February 2001), 30-51.
Winkler, Peter. "Bringing Space Tech Down to Earth," National Geographic World (January 2001), 6-7.
Long, Michael E. "Surviving in Space," National Geographic (January 2001), 6-29.
Gonzales, Laurence. "Mars: An Adventurer's Guide," National Geographic Adventure (September/October 2000),  120-26, 128, 159-61
Newman, Aline Alexander. "Destination: Mars," National Geographic World (January 2000), 14-18.
Long, Michael E. "Mars on Earth," National Geographic (July 1999), 34-51.

"Return to Mars," (1998),
Skurzynski, Gloria. Discover Mars. National Geographic Books, 1998.

Newcott, William R. "Return to Mars," National Geographic (August 1998), 2-29.

"Mars: Our First Close Look," National Geographic (January 1977), 2-7.


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