NASA Planning to Observe Comet About to Come Close to Mars

An artist's concept shows comet Siding Spring (C/2013 A1) heading toward Mars. (PHOTO CREDIT: NASA)
An artist’s concept shows comet Siding Spring (C/2013 A1) heading toward Mars. (PHOTO CREDIT: NASA)

A speeding comet the size of a mountain will come within 87,000 miles of Mars on Oct. 19, and NASA is planning to observe it with just about everything the agency’s got.

In a press conference Thursday, officials described how they will use more than a dozen NASA assets including three Mars orbiters, two Mars rovers, and a suite of telescopes to see comet C/2013 A1, also known as comet Siding Spring, from several different angles and in different lights.

“Normally you send spacecraft to comets,” said Kelly Fast, a program scientist at NASA. “Here, the comet is coming to our spacecraft.”

Comet Siding Spring was first spotted in January 2013, near the end of its million-year journey toward the sun. Scientists estimate that its nucleus is between half a mile and 5 miles wide. The gas cloud that surrounds its head is 12,000 miles across. Its massive tail extends the distance between Earth and the sun.

And it will be going fast. When the comet makes its closest approach to Mars at 11:27 a.m. PDT, it will be hurtling through space at 126,000 miles per hour.

Scientists are eager for any opportunity to study the bodies that zip through our solar neighborhood, but Siding Spring is especially enticing. That’s because it gives humanity our first chance to get an up-close look at a comet from the Oort cloud, a collection of icy bodies at the edge of our solar system.

Embedded in the nuclei of Oort cloud comets are primordial materials from the dawn of the solar system that have been in a deep freeze for billions of years, researchers say. But as the comet moves toward the sun, the ices trapped in its nucleus begin to sublimate, releasing ancient gases into space.

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Deborah Netburn