APL's comet probe launched, in orbit

Contour spacecraft to visit two comets for study in 2003, 2006

July 04, 2002|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

LAUREL - NASA's four-year mission to study comets and their links to the emergence of life on Earth was off to a good start yesterday, with the spacecraft in the right orbit and functioning normally.

The $159 million Contour (for Comet Nucleus Tour) mission lifted off from the Cape Canaveral Air Force Station atop a Delta 2 rocket at 2:47 a.m., just minutes after the last rain clouds cleared away.

Televised views of the fiery ascent drew whoops and applause at the Johns Hopkins University's Applied Physics Laboratory in Laurel, where the spacecraft was designed and built.

APL's mission operations manager, Mark Holdridge, called it a "picture-perfect launch in every respect." Telemetry from the spacecraft showed everything was running well.

Controllers will spend the coming weeks adjusting the 2,138-pound spacecraft's orbit and testing its systems. On Aug. 15, they will fire its main engine and send it toward its first close encounter, with Comet Encke, in November 2003.

Comets are believed to hold the best-preserved evidence of the materials and conditions that combined to form the solar system 4.5 billion years ago. Scientists at APL, Cornell University and 18 other institutions want to know more about the rock and ices they're made of.

Contour and its quartet of cameras and spectrographs should pass as close as 62 miles to Encke's icy core. It will be man's closest venture ever into the dust and gas that make up a comet's dusty halo, or "coma," which solar radiation sweeps into the familiar comet "tail."

Speeding through the dust at 63,000 mph, the Kevlar-shielded craft will make detailed photographs and chemical analyses of the comet's surface and the dust and gas it spews into space.

Paul Mahaffy, a co-investigator from the Goddard Space Flight Center, said scientists want to compare each comet's chemical "fingerprint" - its unique mix of elements - with those on Earth. They hope to learn how much of Earth's oceans, atmosphere and organic compounds - the materials from which, scientists believe, life emerged - might have come from comets.

After passing Comet Encke in 2003, the spacecraft will swing past Earth three times before flying off again for a 2006 encounter with Comet Schwassmann-Wachmann. Contour might have sufficient fuel for as many as two subsequent comet encounters.

An hour after launch yesterday, with Contour safely in orbit, engineers at APL took over control of the flight from the Florida launch team.

"Their job is done, but our job is just beginning," said Robert W. Farquhar, APL's mission director.

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