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Asteroid images reveal new information for NASA


Arizona Daily Wildcat

Illustration courtesy of NASA An illustration of NASA's Cassini spacecraft dramatizes its position in space. The satellite is being used to analyze the Masursky asteroid, which has never been studied from Earth.

By Jay Dirner
Arizona Daily Wildcat,
February 18, 2000
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A team of planetary scientists, including two UA researchers, has taken a leap forward in the study of the solar system with new revelations about an asteroid's composition.

On Jan. 23, NASA's Cassini spacecraft photographed asteroid 2685 Masursky, an object that has never before been studied from Earth. The photographs were taken near the spacecraft's closest approach, about 960,000 miles from Masursky.

Robert West, a NASA scientist at the Jet Propulsion Laboratory in California and University of Arizona doctoral graduate, said the spacecraft got a great photo opportunity.

"Cassini got closer than most spacecraft get to asteroids. It photographed the asteroid in a number of images," he said.

Since the photographs were taken, scientists have been analyzing the asteroid. Carolyn Porco, leader of the Cassini imaging team, issued a press release last week detailing the team's latest findings.

"We now have a reliable estimate of the size of the body because the spacecraft was so much closer than we can get from Earth," said Porco, also a UA Lunar and Planetary Sciences professor, in an interview yesterday.

The imaging team members determined that the asteroid measures nine to 12 miles across, and are currently studying its composition. They wish to determine if Masursky is of the same composition as its neighboring asteroids Gaspra, Ida and Eros.

"We would like to understand what the asteroid's characteristics are," Porco said. "We believe that (Masursky) is a member of a family of asteroids that were created in the disruption of a larger body."

"Cassini measured (the asteroid's) brightness, and it was somewhat darker than expected." West said. "We don't have an explanation for that yet."

Masursky's photographs represent an intermediate mission of Cassini, which has a final destination of Saturn.

Scientists hope to learn more about the asteroid belt which lies between Mars and Jupiter.

Steven Squires, a planetary scientist at Cornell University in Ithaca, N.Y., also works on the Cassini imaging team.

"You can think of asteroids as being some of the 'leftovers' from the original formation of the solar system," he stated in an e-mail interview. "They're extremely old, and in some cases they've changed little since the birth of the solar system. By studying them we're hoping to learn more about how the solar system formed."

Currently, Cassini has traveled over 2 billion kilometers since its launch in fall of 1997. It entered the asteroid belt in mid-November.

The mission is one of NASA's largest, and due to the immense distance Cassini must travel, it will not reach Saturn until 2004. Once there, Cassini will begin its most important work.

"The main objectives of Cassini are to study the Saturn system in detail. A target of particular interest is Titan, which is covered with clouds so that we know very little about its surface," Squires said.

"This is a big, expensive mission, even by solar system exploration standards," he added. "When you tally up the costs it'll come to well over $2 billion."

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