Importance of Big Ears in Space and on Ground in Astrophysics Applications

Big antennas in space and on the ground are important to carry out astrophysics research. In this presentation, I will describe the design and operation of big antennas in Japan: the deployable antenna aboard Halca satellite and the 64 m antenna at Usuda Deep Space Center. Those antennas are master pieces made by electrical and mechanical engineers in close collaboration. Though the used frequency was several GHz, the experience and knowledge obtained from these antennas could be extended to applications in the higher frequency of submillimeter wave and even terahertz. The following application projects will be quoted: 1. Halley’s comet observations in International Armada 2. Space-VLBI development and observation 3. Voyager 2 occultation radio science during Neptune swing-by.