A spectrometer developed by Arizona State University will fly onboard a NASA mission to Jupiter’s Trojan asteroids. The Thermal Emission Spectrometer for the Lucy mission will be a close copy of the OSIRIS-REx Thermal Emission Spectrometer, seen here under construction in the cleanroom on the Tempe campus. Its task in the Lucy mission will be to measure surface temperatures of primitive asteroids as a way of determining their physical properties. Courtesy of Philip Christensen/ASU. The Lucy mission has been chosen under the agency's Discovery Program, a series of cost-capped exploratory missions into the solar system. Lucy will carry an ASU-designed and -developed thermal emission spectrometer which will measure surface temperatures on each asteroid the spacecraft visits. "I'm really excited about this instrument, the third to be built here at SESE," said Philip Christensen, thermal emission spectrometer designer and principal investigator at ASU’s School of Earth and Space Exploration. The Lucy mission, set for a 2021 launch, was named for the iconic fossil skeleton, since it will investigate a particular collection of primitive asteroids that scientists hope may uncover fossils of planetary formation.The mission should arrive among the Trojans in 2027 and visit six asteroids by 2033. Because Jupiter's Trojan asteroids orbit far from the sun, they all have very cold surfaces. The spectrometer’s mission is to measure temperatures with great precision all over each asteroid that the Lucy spacecraft visits. "By mapping how temperatures vary by the local time of day, we can map the surface properties of these previously unknown objects,” Christensen said.