Set to visit and study at least two comets, NASA’s Comet Nucleus Tour
(CONTOUR) should provide the first detailed look at the differences between
these primitive building blocks of the solar system, and answer questions
about how comets act and evolve as they speed toward the sun.

CONTOUR is scheduled to lift off from Cape Canaveral Air Force Station,
Fla., on a three-stage Boeing Delta II expendable launch vehicle during a
25-day launch window that opens July 1 at 2:56 a.m. (EDT). The spacecraft
will orbit Earth until Aug. 15, when it should fire its main engine and
enter its comet-chasing orbit around the sun. NASA TV is scheduled to
provide live coverage of the launch beginning at 1:30 a.m. (EDT)

CONTOUR’s flexible four-year mission plan includes encounters with comets
Encke (Nov. 12, 2003) and Schwassmann-Wachmann 3 (June 19, 2006), though it
can add a study of a “new” comet from the outer solar system should one be
discovered in time for CONTOUR to catch it. CONTOUR will examine each
comet’s “heart,” or nucleus, which scientists believe is a chunk of ice and
rock, often just a few kilometers across and hidden from Earth-based
telescopes beneath a dusty atmosphere and long tail.

“The CONTOUR mission will be NASA’s second mission dedicated solely to
exploring these largely unknown members of our solar system,” says Dr.
Colleen Hartman, Director of the Solar System Exploration Division, NASA
Headquarters, Washington. “CONTOUR joins our other operating mission,
Stardust, which is on its way to bring a sample of a comet back to Earth.
Next year, Deep Impact will launch to join our fleet of comet-exploring
spacecraft. These missions all help us find answers to the fundamental
questions of how our planet may have formed and evolved, and how life may
have began on Earth and perhaps elsewhere in the universe.”

The 8-sided solar-powered craft will fly as close as 100 kilometers (62
miles) to each nucleus, at top speeds that could cover the 56 kilometers
between Washington and Baltimore in two seconds. A 5-layer dust shield of
heavy Nextel and Kevlar fabric protects the compact probe from comet dust
and debris.

“Comets are the solar system’s smallest bodies, but among its biggest
mysteries,” says Dr. Joseph Veverka, CONTOUR’s principal investigator from
Cornell University, Ithaca, N.Y. “We believe they hold the most primitive
materials in the solar system and that they played a role in shaping some of
the planets, but we really have more ideas about comets than facts. CONTOUR
will change that by coming closer to a comet nucleus than any spacecraft
ever has before and gathering detailed, comparative data on these dynamic

CONTOUR’s four scientific instruments will take pictures and measure the
chemical makeup of the nuclei while analyzing the surrounding gases and
dust. Its main camera, the CONTOUR Remote Imager/Spectrograph (CRISP), will
snap high-resolution digital images showing car-sized rocks and other
features on the nucleus as small as 4 meters (about 13 feet) across. CRISP
will also search for chemical “fingerprints” on the surface, which would
provide the first hard evidence of comet nuclei composition.

The targets were selected because of their diversity and relative closeness
to Earth during encounter time – less than 50 million kilometers (31 million
miles) – allowing astronomers to observe the comets during the encounters.
Encke has been seen from Earth more than any other comet; it’s an “old” body
that gives off relatively little gas and dust but remains more active than
scientists expect for a comet that has passed close to the sun thousands of
times. Schwassmann-Wachmann 3, on the other hand, was discovered just 70
years ago and recently split into several pieces, intriguing scientists with
hopes that they might see fresh, unaltered surfaces and materials from
inside the comet.

“The key to the CONTOUR mission is to visit a diverse range of comets, from
an evolved comet such as Encke, to a younger comet like SW3 or even a new
comet never seen in this part of the solar system,” says Mary C. Chiu,
CONTOUR project manager at The Johns Hopkins University Applied Physics
Laboratory (APL), Laurel, Md. “Our mission plan gives us that flexibility.”

CONTOUR’s orbit loops around the sun and back to Earth for annual “gravity
swings” toward its targets; these maneuvers bend CONTOUR’s trajectory and
help it reach several comets without using much fuel. CONTOUR will cruise
unattended between comet encounters and Earth swingbys in a spin-stabilized
“hibernation” mode, helping the mission reduce operations and communications

The $159 million CONTOUR is the sixth mission in NASA’s Discovery Program of
lower cost, scientifically focused exploration projects. APL manages the
mission, built the spacecraft and its two cameras, and will operate CONTOUR
during flight. NASA’s Goddard Space Flight Center, Greenbelt, Md., provided
CONTOUR’s neutral gas/ion mass spectrometer and von Hoerner & Sulger, GmbH,
Schwetzingen, Germany, built the dust analyzer. NASA’s Jet Propulsion
Laboratory, Pasadena, Calif., will provide navigation and Deep Space Network
(DSN) support. Cornell’s Veverka leads a science team of 18 co-investigators
from universities, industry and government agencies in the U.S. and Europe.

More information on CONTOUR is available on the Web at

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