Akatsuki (spacecraft)

Akatsuki was 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, The budget for this mission is ¥14.6 billion () for the satellite and ¥9.8 billion (US$116 million) for the launch. Observations included 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 were designed to confirm the presence of lightning and to determine whether volcanism occurs currently on Venus. The mass of the science payload was . Propulsion was provided by a bi-propellant, hydrazine-dinitrogen tetroxide orbital maneuvering engine and twelve mono-propellant hydrazine reaction control thrusters, eight with of thrust and four with . The total propellant mass at launch was . Communication was handled via an 8 GHz, 20-watt X-band transponder using the high-gain antenna. The high-gain antenna was flat to prevent heat from building up in it. Akatsuki also had a pair of medium-gain horn antennas mounted on turntables and two low-gain antennas for command uplink. The medium-gain horn antennas were used for housekeeping data downlink when the high-gain antenna was not facing Earth. ==Instruments==

The scientific payload consisted of six instruments. Five imaging cameras were used to explore Venus in wavelengths from ultraviolet to the mid-infrared: • the Lightning and Airglow Camera (LAC) searched for lightning in the visible spectrum (552–777 nm) • the ultraviolet imager (UVI) studied the distribution of specific atmospheric gases such as sulfur dioxide and the famous unknown absorber at ultraviolet wavelengths (283–365 nm) • the longwave infrared camera (LIR) studied the structure of high-altitude clouds at a wavelength where they emit heat (10 μm) • the infrared 1 μm camera (IR1) imaged the night side heat radiation (0.90–1.01 μm) emitted from Venus's surface and help researchers to search for active volcanoes. While on the day side, it sensed the solar near-infrared radiation (0.90 μm) reflected by the middle clouds. Operation of the instrument was terminated in December 2016 due to an electronic failure. • the infrared 2 μm camera (IR2) studied the night side lower clouds' opacity to the thermal emission from the surface and deeper atmosphere (1.74–2.32 μm). It also sensed on the day side the band at 2.02 μm, which can be used to infer the altitude of the top of the clouds. Finally, the 1.65-μm filter was used during the cruise phase to study the zodiacal light. Operation of the instrument was terminated in December 2016 due to an electronic failure. • the Ultra-Stable Oscillator (USO) for performing radio occultation experiments. == Public relations ==

A public relations campaign was held between October 2009 and January 2010 by the Planetary Society and JAXA, to allow individuals to send their name and a message aboard Akatsuki. Names and messages were printed in fine letters on an aluminium plate and placed aboard Akatsuki. 260,214 people submitted names and messages for the mission. Around 90 aluminium plates were created for the spacecraft, including three aluminium plates in which the images of the Vocaloid Hatsune Miku and her super deformed-styled figure Hachune Miku were printed. ==Operations==

Launch Akatsuki left the Sagamihara Campus on 17 March 2010, and arrived at the Tanegashima Space Center's Spacecraft Test and Assembly Building 2 on 19 March. On 4 May, Akatsuki was encapsulated inside the large payload fairing of the H-IIA rocket that launched the spacecraft, along with the IKAROS solar sail, on a 6-month journey to Venus. On 9 May, the payload fairing was transported to the Tanegashima Space Center's Vehicle Assembly Building, where the fairing was mated to the H-IIA launch vehicle itself. The spacecraft was launched on 20 May 2010 at 21:58:22 (UTC) from the Tanegashima Space Center, Orbit insertion failure 2028. In April 2024, degraded precision of attitude control resulted in failure of communication. JAXA declared the spacecraft's loss of contact with Earth on May 29, 2024. Operation was terminated officially on 18 September 2025. ==Science==

Three hours after insertion in December 2015 and in "a few glimmers in April and May" 2016 the craft's instruments recorded a "bow-shape feature in the atmosphere stretching 6,000 miles, almost pole to pole — a sideways smile". ==Gallery==

File:Venus - October 24 2018.png|An image of Venus with AKATSUKI Ultraviolet Imager (UVI) 283 365 UVI 2018 06 03 08 03.jpg|An image of Venus with a crescent shaped area that is illuminated by sunlight. The image was taken with UVI. 174 226 232 date 2016 07 11 14 10.jpg|An image of the night side of Venus with the AKATSUKI 2-μm Camera (IR2). In the dark areas the light is absorbed by Carbon dioxide| clouds. 097 101 surface date 2016 07 12 04 05.jpg|An image of the surface of Venus with the AKATSUKI 1-μm Camera (IR1) ==See also==