Eric Hochberg has studied coral reefs for two decades, but the marine ecologist is about to see them in a fresh light. Beginning on 6 June, Hochberg and his colleagues will use a specially outfitted NASA aeroplane to map the spectra of sunlight reflecting off reefs spread across the Pacific Ocean far below. The scientists aim to tease out the spectral signatures of coral, algae and sand — and to check the health of the reefs.