Space Science

Abstract

Even without Itokawa, his colleagues implemented his vision of a programme of small satellites for space science, continuously upgrading its small, solid-fuel rockets from the Mu series to Epsilon rockets. These scientific satellites covered a broad range from the atmosphere to the ionosphere to the magnetosphere (Tansei, Shinsei, Denpa, Kyokko, Jikiken, Ohzora), but Japan also built excellence in X-ray astronomy (Tenma, Ginga, Asuka, Suzaku, Hitomi); solar astronomy (Taiyo, Yohkoh and Hinode); and infrared astronomy (Akari). In the new century, the new rocket Epsilon was introduced, launching two scientific missions: Hisaki, focussed on Jupiter and Arase, the magnetic fields. These missions constituted a relatively small part of the overall space budget, so they were an illustrative example of relatively low cost but highly productive missions delivered by small but reliable rockets. Humble sounding rockets, their origins going back to the 1950s, enabled the continuation of a limited but valuable range of scientific missions. The missions from Tansei (1971) through to Arase (2016) constitute an unbroken thread of small scientific satellites, ‘Hideo Itokawa’s dream’.