Space Applications of Terahertz Present and Potential Future

Despite great scientific interest since at least the 1920's, the THz frequency range remains one of the least tapped regions of the EM spectrum. Many scientists and engineers do research in THz, from source to transmission and receiver to imager. Up to now compared with traditional and optical technologies, the applications of THz is relatively narrow. In the space field, SWAS (The Sub-millimeter Wave Astronomy Satellite) was launched in 1998, which NASA to study molecular cloud composition in the galactic plane by examining sub-millimeter(500GHz) spectral lines. Planck/Herschel explorer launched by ESA in 2009, for receiving CMB(cosmic microwave background) between microwave to THz(similar to 1THz), search relics of Big Bang 13.8 billion years ago. These projects all are focusing on scientific research. In China, GEO meteorological satellite FY-4 launched in 2016, has 424GHz instrument for testing. This uses give THz a dawn of applications. But THz still face huge challenges which compare to traditional microwave particular in space. This paper reviews some programs of THz in space. In addition to present applications, such as upper atmosphere research, water cycle, cosmos research(CMB),the future applications of air plane communication and monitoring of hazard asteroids for Earth are suggested in this paper.