Studying impact flashes to detect missile and meteorite composition

Studying impact flashes to detect missile and meteorite composition Gaby Clark Scientific Editor Andrew Zinin Lead Editor Southwest Research Institute, or SwRI, is studying impact flashes generated by high-speed collisions. One application of understanding impact flashes is to remotely identify what materials are involved in the collisions. Advances in understanding optical impact flashes can be highly beneficial for missile defense, making it possible to determine the composition of an intercepted missile and its payload. The work could also aid scientists in identifying the origins of meteorites or asteroids impacting surfaces, based on their composition. "When a meteorite strikes the surface of the moon or planet, the energy of the impact creates a flash that gives off so much energy that the chemical signatures of its constituent materials are visible at different wavelengths," said Dr. Pablo Bueno, a lead engineer in SwRI's Mechanical Engineering Division. Bueno and Roberto Enriquez-Vargas, a SwRI senior research engineer, recently completed a project that developed and refined methods for using high-speed spectroscopy to analyze the light emitted during hypervelocity impacts, where the impact flashes typically last only a few microseconds. The short time window required capturing spectral data quickly and precisely. Bueno and Enriquez-Vargas used SwRI's two-stage light-gas guns to create hypervelocity impacts representative of missile strikes or asteroid impacts. The large gun system generates velocities up to 7 kilometers per second (15,660 mph). The system is 22 meters (72 feet) long and is traditionally used to study ballistics. Because the impact occurs so swiftly and the flash decays rapidly, Bueno and Enriquez-Vargas developed a laser-based triggering system to precisely detect the instant an impact occurs, accurately measuring impact timing within 100 nanoseconds, or one 10-millionth of a second. SwRI studied the distinct spectra of the materials emitted under the intense heat and pressure created by the impact, allowing researchers to identify materials present. The researchers also tested how different factors could alter the impact flashes. "Thicker targets produced brighter, longer flashes," Bueno explained. "Higher atmospheric pressure created broader and thicker emission lines in the spectra, and in many cases materials at high temperature behaved differently than they did when impacted at room temperature." Provided by Southwest Research Institute