Akatsuki (spacecraft)

Akatsuki, also known as the Venus Climate Orbiter (VCO) and Planet-C, is a Japan Aerospace Exploration Agency (JAXA) space probe tasked with studying the atmosphere of Venus. It was launched aboard an H-IIA 202 rocket on 20 May 2010, but failed to enter orbit around Venus on 6 December 2010. After the craft orbited the Sun for five years, engineers successfully placed it into an alternative Venusian elliptic orbit on 7 December 2015 by firing its attitude control thrusters for 20 minutes and made it the first Japanese satellite orbiting Venus. By using five different cameras working at several wavelengths, Akatsuki is studying the stratification of the atmosphere, atmospheric dynamics, and cloud physics. Astronomers working on the mission reported detecting a possible gravity wave (not to be confused with gravitational waves) in Venus' atmosphere in December 2015. Akatsuki is Japan's first planetary exploration mission since the failed Mars orbiter Nozomi probe which was launched in 1998. Akatsuki was originally intended to conduct scientific research for two or more years from an elliptical orbit around Venus ranging from in altitude, but its alternate orbit had to be highly elliptical ranging between at its nearest point and about at its farthest. This larger orbit takes 10 days to complete instead of the originally planned 30 hours. The budget for this mission is ¥14.6 billion () for the satellite and ¥9.8 billion (US$116 million) for the launch. Observations include cloud and surface imaging from an orbit around the planet with cameras operating in the infrared, visible and UV wavelengths to investigate the complex Venusian meteorology and elucidate the processes behind the mysterious atmospheric super-rotation. On Venus, while the planet rotates at at the equator, the atmosphere spins around the planet at . Other experiments are designed to confirm the presence of lightning and to determine whether volcanism occurs currently on Venus. The main bus is a box with two solar arrays, each with an area of about .