Tuesday, May 18, 2010

Japanese Spacecraft to Study Venus Atmosphere

Akatsuki will arrive in Venus' orbit in November. (JAXA)

(UPDATED from May 5, 2010) -- A Japanese space observatory will depart Earth on Friday bound for Venus as it begins a multi-year mission to study the planet's mysterious atmosphere.

The Venusian atmosphere as a whole is one of the great mysteries in our solar system -- from it's make up and fast rotating upper atmosphere to why it differs so much from it's twin planet, Earth.

Launch of the JAXA (Japan Aerospace Exploration Agency) H-2A-200 rocket with the Venus Climate Orbiter "Akatsuki" spacecraft is scheduled for May 20 at 5:58:22 pm EDT (2158 GMT), or 6:58 am local time on May 21, from the Tanegashima Space Center in Japan.

The Akatsuki observatory, also known as PLANET-C, will spend nearly five years investigating the make-up of Venus' high carbon dioxide atmosphere with high resolution mapping.

The spacecraft is scheduled to arrive at Venus this November.

"Akatsuki is the world's first planetary probe that deserves to be called a meteorological satellite," JAXA project scientist Dr. Takeshi Imamura explained. "The unique feature of this mission is that it will map the movement of the Venusian atmosphere in three dimensions, by taking continuous images of a broad swath all at once, using different wavelengths ranging from infrared to ultraviolet."

The planet's atmosphere of 96% carbon dioxide creates surface temperatures which average 860 degrees Fahrenheit. Venus' heavy atmosphere, which includes nearly 4% nitrogen, is ninety-two times heavier than that here on Earth.

The box-shaped spacecraft will orbit the planet once every 30 hours as it flies an elliptical orbit of 186 x 49,710 miles above.

Earth's sister planet orbits the Sun from a mean distance of 67 million miles, and has no natural satellites of it's own.

Akatsuki will carry several science instruments and cameras, including an ultraviolet imager and a Longwave infrared camera.

"Akatsuki is equipped with five cameras," Imamura explained in a recent interview. "One of them, a near-infrared camera, will be able to peer through the thick clouds of sulfuric acid and observe the surface of Venus, which is normally completely obscured by these clouds. In addition to studying meteorological phenomena, we might be able to see whether Venus has any active volcanoes."

Venus does have over 160 volcanoes which have added a vast amount of sulfuric acid to the planet's atmosphere.

A secondary payload which will become a test bed for future solar sail spacecrafts will accompany the planetary probe as they leave earth orbit.

A small Japanese solar power sail experiment known as IKAROS (Interplanetary Kite-Craft Accelerated by Radiation of the Sun) will depart Earth and speed toward Venus as well.

A circular core will begin moving out into outer space and begin to rotate at 20 rotations per minute. Then two weeks later, it will deploy a 20-meter (66 feet) diagonal square solar array blanket which will surround the rotating core.

The solar sail is only .0075 mm or .0003 of an inch thick, according to JAXA.

The solar array blanket is supported by four masts, and it will be these masts which will support the very thin polyimide solar cells.

The IKAROS demonstration will pave the way for a larger platform which will span 50 meters (164 feet) across as JAXA launches a solar sail probe toward Jupiter late this year.

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