Terahertz heterodyne technology for astronomy and planetary science

Heterodyne detection techniques play an important role in high-resolution spectroscopy in astronomy and planetary science. In particular, heterodyne technology in the Terahertz range has rapidly evolved in recent years. Cryogenically cooled receivers approaching quantum-limited sensitivity have been developed up to 2 THz for large astronomy projects like ESA's Herschel Space Observatory and the Atacama Large Millimeter Array (ALMA) as well as other observing facilities. Future space- and ground-based submillimeter observatories require heterodyne detectors and receivers up to 6 THz and beyond. Recent developments in superconducting mixer as well as local oscillator technology bring such receivers into reach. This short article summarizes the main technological achievements of Terahertz heterodyne technology, and gives an outlook into future developments.