An early Japanese satellite launched by ISAS (Institute of Space and Astronautical Science) to carry out measurements of the ionosphere; also known as REXS. Launch date Aug. 19, 1972 Launch vehicle M-3S Launch site Kagoshima Orbit 238 × 6,322 km × 31.0° Mass (at launch) 7... Found on http://www.daviddarling.info/encyclopedia/D/Denpa.html