A new receiver is capable of detecting and amplifying very-high- frequency signals with very fine frequency resolution, so it can detect the spectral lines, or chemical fingerprints, of interstellar molecules that emit radio signals at terahertz frequencies — the highest frequencies ever achieved with any radio receiver. The unique detector of astronomical radiation, developed at the Harvard-Smithsonian Center for Astrophysics (CfA), in Cambridge, Mass., and tested at the Heinrich Hertz Submillimeter Telescope (HHT) on Mount Graham, Ariz., made the first ground-based measurements of radio emission from interstellar molecules in the “terahertz waveband” — a virtually unexplored part of the astronomical spectrum. The unique combination of the detector, the excellent high dry site and the accurate telescope were all necessary for this milestone in radioastronomy, astronomers say.