II-VI became part of history this past 4th of July as a Zinc Selenide prism and metal mirrors produced by the Saxonburg Diamond Turning Department were used on the Deep Impact space project. This project involved the collision of a probe with a comet one-half the size of Manhattan Island in order to study the comet's makeup.

The space probe traveled 173 days and 268 million miles to reach Tempel 1 in time for the July 4th blast. The one-meter-wide impactor containing the mirrors was released into the path of the comet, with a flyby craft containing the II-VI prism located 310 miles away. The comet's rate of speed through space was 23,000 miles per hour. Cost of the program was $333 million.

The goal of the NASA Mission was to blast out dust and ice to reach the untouched primordial material within the comet. The impactor was expected to leave a crater in the comet ranging in size from a house to a football stadium. Images were radioed back to Earth showing the approach, impact, and aftermath. Those images were collected by a High Resolution Instrument on the flyby spacecraft. This instrument, designed and built by Ball Aerospace & Technologies Corporation, consists of a telescope, infrared spectrometer, and multispectral CCD camera (click here.).

Ball Aerospace used a novel optical design approach in which a Zinc Selenide prism, which produces dispersion for the spectrometer, was combined with an aspheric corrector lens surface. The resulting component greatly simplifies the remaining mirrors in the optical design. However, the Zinc Selenide prism was a challenging component to manufacture. II-VI used all of its manufacturing, metrology, and coating experience to successfully produce this prism.

The probe offers potential answers to questions about the origins of our solar system as these formation materials change little within the comet. These frozen balls of ice, rocks, and dirt are the remnants of the process whereby clouds of gas and dust condensed to form the sun and planets within our solar system approximately 4.6 billion years ago. Gravitational pull brings them into the inner solar system. Data generated by the Deep Impact probe could provide information on the formation of our solar system, the makeup of comets, and the role these objects have had on the early history of our planet as well as the origins of life on Earth.

Initial data shows that an immense cloud of powdery material—of the consistency of talc—was released upon initial impact. Already, this information has changed science's understanding of the composition of a comet. Data will continue to be evaluated for quite a long time.

More information on the Deep Impact project (including a photo of the II-VI prism here) is available at the NASA site (click here).