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Japan readies first mission to Venus for 2010 launch

BY STEPHEN CLARK

SPACEFLIGHT NOW

Posted: October 24, 2009



Japan has christened its next deep space mission Akatsuki, meaning dawn in English, a half-year before the spacecraft is dispatched toward Venus to analyze the planet's smothering atmosphere.

Artist's concept of the Akatsuki spacecraft over Venus. Credit: JAXA/Akihiro Ikeshita



The name Akatsuki was selected because Venus shines brightly as the morning star just before sunrise, according to the Japan Aerospace Exploration Agency. The mission was previously named Planet C and is Japan's first spacecraft to be sent to Venus. The 1,058-pound robotic probe will launch aboard an H-2A rocket from Japan's Tanegashima spaceport around May 20, 2010. If Akatsuki departs Earth in May or June, the spacecraft will arrive at Venus in December 2010. The satellite has spent the summer in comprehensive performance testing before it is shipped to Tanegashima this winter. Akatsuki will be Japan's second interplanetary mission after the Nozomi spacecraft that twice missed entering orbit around Mars after launching in 1998. The Venus orbiter also closely follows JAXA's first lunar probe, Kaguya, and the maiden flight of the HTV cargo ship for the International Space Station. After its six-month cruise through space, Akatsuki will enter an equatorial orbit around Venus stretching from just above the planet's blanketing atmosphere to an altitude of nearly 50,000 miles. Six experiments will allow Akatsuki, also called Venus Climate Orbiter, to peer deep into the planet's atmosphere and even study surface activity. The Venusian carbon dioxide atmosphere causes a runaway greenhouse effect that drives surface temperatures to about 860 degrees Fahrenheit. Cloud formations in the atmosphere swirl around the planet at speeds of up to 250 mph. Scientists want to know more about the mechanics of such a world, and Akatsuki will help Japanese researchers answer those questions. Akatsuki's sensor package includes two infrared cameras to observe lower level clouds and collect data on potential active volcanoes. A longwave infrared instrument and ultraviolet imager will look at cloud tops and track global storm systems to produce wind maps. A lightning and airglow camera will take pictures of the night side of Venus. The sixth investigation is a radio science experiment to derive vertical temperature and vapor density profiles of the atmosphere. This data will be produced on the ground based on the atmosphere's effects on radio signals received from the spacecraft. JAXA describes Akatsuki as the first interplanetary weather satellite. Akatsuki will operate for at least two Earth years, and scientists hope the Japanese mission will arrive in time to work with Europe's Venus Express probe already at the planet. Venus Express is in an extended mission through December 2012 after beginning its mission at Venus in April 2006. If Akatsuki makes it to its destination while Venus Express is still active, it would be the first time since 1992 that two spacecraft operated simultaneously in orbit around Venus.