CU Sounding Rocket Instrument To Probe Comet Hale-Bopp March 24

March 18, 1997

A team of faculty and students from the University of Colorado at Boulder will fly an ultraviolet spectrograph on a NASA sounding rocket from White Sands, N.M., March 24 to probe the chemical makeup of comet Hale-Bopp.

The two-stage sounding rocket, slated for launch at 8:15 p.m. will rise to a height of 150 to 200 miles, said Erik Wilkinson, a research associate at CU-Boulder’s Center for Astrophysics and Space Astronomy who designed and built the instrument hardware. The CU-Boulder spectrograph will take from 5 minutes to 7 minutes of data on the chemical composition of the comet by observing it in the ultraviolet portion of the light spectrum, he said.

The researchers are interested in charged oxygen molecules released by Hale-Bopp, which should provide information on the comet’s temperature and interactions with solar radiation as it moves toward the sun, said CASA Research Associate James Green, principal investigator on the experiment. They also will search for traces of noble gases like argon and neon, thought to have been locked up in the comets since the objects first formed early in the solar system.

While any noble gases present in the comets were initially trapped at extremely low temperatures, each gas is believed to have been “locked in at a unique threshhold temperature,” said Green. Solar radiation warms the comets as they approach the sun and releases the gases into space for the first time, providing valuable clues to the solar system’s earliest history.

“There is only one way for noble gases to get into comets,” said Green. “So we can use the gases as temperature indicators to estimate the conditions under which the comet formed.”

Comets are believed by astronomers to reside in the leftovers of a large cloud beyond Pluto that initially formed the solar system. They occasionally get knocked on a path toward the sun, providing spectacular viewing for the public and a variety of unique research opportunities for scientists.

The CU-Boulder spectrograph has been flown twice before on sounding rockets launched from Australia and New Mexico to observe other celestial phenomena, said Green. It was swiftly modified for the Hale-Bopp mission following approval from NASA officials.

“All comets are out of the ordinary, but this one appears to be a very unique comet, “ said Wilkinson. “Since they do not come through our solar system very often, we have a great opportunity to learn some new things.”

While data gathered by the spectrograph will be transmitted to Earth in real time by radio telemetry, it may take weeks to months for CU-Boulder faculty and students to analyze the data.

Other CASA team members include technical engineer James McDonald and graduate students Kurt Gunderson and Ryan McLean.

After the sounding rocket reaches its maximum height, the scientific payload will be parachuted back to Earth. Military helicopters will be used to recover the CU payload, which is expected to drift up to 70 miles downwind from the White Sands Missile Range launch site.

The CASA spectrograph is the first of four NASA-sponsored sounding rocket missions to be launched from White Sands during late March and early April to observe comet Hale-Bopp.

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