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Distributed June 23, 2005
Contact Wendy Lawton

Cosmic Collision: Peter Schultz Helps Make NASA Mission a Smash

Peter Schultz, professor of geological sciences at Brown University, is behind what promises to be a flashy July 4 fireworks display: Slamming an 820-pound projectile into a comet moving at 23,000 miles per hour – producing an enormous crater that will offer NASA scientists their first peek inside these primordial balls of ice and dust. [Return to news release 04-148.]

PROVIDENCE, R.I. — Planetary geologist Peter Schultz is a crater connoisseur, studying planetary holes and hollows and figuring out how and when they were made.

For the last 25 years, the Brown University professor of geological sciences has traveled to the Vertical Gun Range at NASA’s Ames Research Center in Silicon Valley, Calif., to simulate cosmic collisions between planets and roving objects such as asteroids.

To conduct his experiments, Schultz fires marble-sized beads – even meteorites – into surfaces ranging from ice and sand to dust and mud. The projectiles, which travel more than 10 times faster than a speeding bullet, make craters of all shapes and sizes. Schultz studies the collisions and the craters – sprays of debris, the diameter and depth of depressions – to understand the forces that shaped features on planets such as Earth, Mars and Venus as well as satellites such as the Moon.

His work also helps scientists understand the consequences of these impacts. For example, Schultz discovered that an asteroid collision 3.3 million years ago in what is now southern Argentina coincided with a drastic cooling of the planet and the disappearance of 35 different types of ancient mammals. The impact may have caused the regional extinctions or sparked the sudden climate change that led to their disappearance.

Schultz’ expertise landed him a spot in the inner scientific circle for Deep Impact, the historic mission inside a comet. The mission is lead by the Jet Propulsion Lab and the University of Maryland.

On July 4, 2005, an 820-pound copper projectile will blast a crater into comet Tempel 1, a dark, spud-shaped behemoth weighing between 10 and 250 billion tons. Like all comets, Tempel 1 consists of the frozen remains of material that formed the solar system. But what, precisely, is this stuff? How is it put together?

Deep Impact aims to find out by making a deep depression in the comet. Cameras and an infrared spectrometer aboard an orbiter will record the collision, relaying images and data that can be used to determine the comet’s composition.

It was up to Schultz and his colleagues to come up with collision scenarios. Schultz ran dozens of experiments at the Ames Vertical Gun Range, varying the makeup of test surfaces, to record the trajectory of flying debris and crater size and speed of formation. Schultz worked with different combinations of dust, ice and snow in different thicknesses.

“We know comets are like dirty snowballs,” Schultz said. “But is the crust thick or thin? Is the interior light or dense? By running these scenarios, we can make better predictions when the real impact happens.”

Schultz’ calculations helped NASA determine where cameras should be positioned on the Deep Impact probe – which Schultz helped to design.

“This is heady stuff,” Schultz said. “The ice inside comets has been in the deep freeze since the creation of the solar system. Now we are finally going to see what this stuff looks like and what it is made of. This is important information. Gases in our own atmosphere may have come from a comet collision. And what about the oceans? Where did our water come from? Deep Impact may provide some answers.”

“The project is also cool because it will give us our closest look at a comet,” he said. “Comets are such mysteries. They remind us that we have visitors from space.”

Along with his teaching, Schultz serves as director of Brown’s Northeast Regional Planetary Data Center and as director of the Rhode Island Space Grant Program.

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