The "Venus Climate Orbiter" mission was approved in the spring of 2001, was later given the Japanese name "Akatsuki", meaning the dawn. Akatsuki is the first "planetary meteorology" mission of which primary target is the Venus' super-rotating atmosphere. To obtain the 3-dimensional views of the atmosphere of Venus, Akatsuki is equipped with 5 cameras, from the ultraviolet (UVI) to the thermal infrared (LIR), plus the ultra-stable oscillator for radio science (RS). Two near-infrared cameras, IR1 and IR2, as well as the lightning/airglow camera (LAC), complete the instrument set. Akatsuki, launched on 21 May 2010, attempted the Venus orbit insertion (VOI-1) on 7 Dec 2010 but failed. After orbiting around the sun for 5 years, it finally became an orbiter around Venus at the second attempt (VOI-R1) on 7 Dec 2015. Akatsuki's unique orbit, near the equatorial plane and the same direction of motion as the Venus' super-rotation, is best suited to study the atmospheric dynamics. The major findings of Akatsuki include "stationary gravity wave features", "equatorial jets in the middle to lower clouds", "sharp and long-lived cloud discontinuity", "global structure of thermal tides", and "importance of thermal tides to the super- rotation". The mission overview and some representative findings by the mission will be presented.
Professor at Department of Solar System Sciences, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (ISAS/JAXA)