Terahertz is the primary frequency for line and continuum radiation from cool ( 5 - 100 K ) gas ( atoms and molecules ) and dust . This viewgraph presentation reviews the reasons for the interest in Terahertz Space Applications ; the Terahertz Space Missions : in the past , present and planned for the future , Terahertz source requirements and examples of some JPL instruments ; and a case study for a flight deliverable : THz Local Oscillators for ESA s Herschel Space Telescope