Deputy Principal Investigator on NASA’s MESSENGER mission to Mercury, Carnegie’s Larry Nittler is playing a leading role in determining the chemical composition of the Solar System’s innermost planet. MESSENGER, led by former Terrestrial Magnetism director Sean Solomon, has been returning a wealth of scientific data since entering obit around Mercury in March 2011 for a yearlong mission. MESSENGER will end its mission April 30, 2015, over three years longer than planned and far surpassing goals. The plan was to take 2,500 images of the planet, but the little workhorse has returned more than 250,000. Watch a sampling here.