Register for an account


Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.


Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.

The Sciences

50: NASA Takes a Wild Comet Ride

By Kathy A SvitilJanuary 2, 2005 6:00 AM
Comet Wild 2, seen just before (left column) and after (right column) Stardust’s closest encounter, has a bizarre, shallow-pitted surface that baffles scientists. | Courtesy of NASA


Sign up for our email newsletter for the latest science news

Most comets reside unseen in the dark outer reaches of the solar system, frozen relics of the era when the planets formed 4.6 billion years ago. When they pass close to the sun’s light and heat, they can become spectacularly visible, but even then they are so small and fast-moving that they are difficult to study. So researchers could barely contain their excitement last January when NASA’s Stardust spacecraft came within 150 miles of comet Wild 2, capturing the best look ever at one of these enigmatic objects.

Close-up photos revealed that the 3.1-mile-wide clump of rock and frozen gas is covered with deep craters and vast sinkholes, tall spires, flat-topped mesas, and sheer cliffs. “A lot of people imagined that comets were just piles of gravel and sand,” says Donald Brownlee of the University of Washington, head of the Stardust research team. “But you cannot make vertical cliffs and pinnacles up to 100 meters [300 feet] high out of sand. Whatever Wild 2’s surface is, it has to have some strength.”

More clues about the composition of comets are on the way. When Stardust zoomed by Wild 2 it mowed through a cloud of loose debris surrounding the comet. While a shield protected the spacecraft itself, a small collector scooped up bits of comet stuff. This package is now headed earthward and will arrive in January 2006 via a parachute drop reminiscent of the one used for the Genesis probe. Scientists just hope for a softer landing this time around.

3 Free Articles Left

Want it all? Get unlimited access when you subscribe.


Already a subscriber? Register or Log In

Want unlimited access?

Subscribe today and save 70%


Already a subscriber? Register or Log In