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CU’s Harch writes the programs that tell spacecraft what to do and where to go By Blaine P. Friedlander Jr. While cold, autumnal winds whip across upstate New York, some 40 million miles away, a small spacecraft traveling at 60,000 miles per hour will pass within 62 miles of the rocky, icy nucleus of Comet Encke. "With a speed like that," said Ann Harch, Cornell researcher in space sciences, "CONTOUR will be screaming by Encke." On Nov. 12, 2003, NASA's CONTOUR, the Comet Nucleus Tour mission, with its Cornell-directed science team hanging in suspense, will make the closest encounter yet with the heart of a comet, its nucleus. Aboard the spacecraft are four scientific instruments: one to take the comet pictures, one to measure its gases, another to monitor its dust, and the last to take images of Encke's inner coma in wavelengths sensitive to ionized gas. The command sequences that will operate the imagers and spectrograph will be written by Harch. The key to the mission is the CONTOUR Remote Imager Spectrograph, or CRISP. With about six minutes to go before the Encke nucleus encounter, CRISP's mirror will peek out from behind the spacecraft's dust shield and locate the comet. The instrument then will begin closed-loop tracking, essentially putting the spacecraft on navigation auto-pilot. On previous missions, images from a spacecraft were sent to engineers on Earth who then had to calculate the direction. During the 30 seconds to a minute it will take the spacecraft to speed by Encke's nucleus, there will be no time for ground interaction. The CRISP instrument will have to take over and track the comet itself, while recording the best images and spectra. For this special job, Harch has the perfect mind. She not only is a veteran of previous high-pressure missions, she also enjoys thinking in three dimensions. In her effort to ensure success, she checks, double checks and triple checks her mathematics, and then checks them again. "Having a healthy dose of paranoia is a sign of a good mission ops engineer," she said. For the past year, Harch has learned CRISP’s intricacies and idosyncracies from mission engineers at NASA's Jet Propulsion Lab (JPL) in Pasadena, Calif., and at the John Hopkins University Applied Physics Laboratory (APL), which is managing the mission. The engineer who built CRISP likened the ground-testing of CONTOUR's instruments to getting a learner's permit to drive. "Inflight testing of the instruments this fall will be our driving test," said Harch. After that, she will spend the next year working closely with mission operations specialists and engineers from JPL and APL designing details of the Earth flyby and Encke encounter. Harch never set out to explore the cosmos. She graduated from the University of California-Los Angeles with a bachelor’s degree in geology and intended to work for an oil company, until the economy soured in the early 1980s. With her strong mathematics background, she learned of an instrument programmer position at JPL, and became an instrument sequencer on the Voyager mission to the outer planets. Her first task was to design direction sequences to search for rings during the January 1986 Uranus flyby. Her imaging mosaics –- lots of pictures taken across a broad area –– enabled scientists for the first time to detect rings around Uranus. "It was the first mission I had designed sequences for, and we were at JPL watching those images come back from Voyager. The first image came down and it was black. The second came down and it was black. The third, fourth and fifth images came down and they were black. My heart was sinking." It turned out that the display had the wrong settings and the pictures had not yet been brightened. Harch mused,"Instead
of being a geologist focussing on Earth, I’'m exploring space
with robotic instruments, very sophisticated, very expensive instruments,"
she says. " Being one of the first to see these objects, whether
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