Japan Launches New Venus Probe and Solar Sail
Japan's Venus Climate Orbiter Akatsuki and the Ikaros solar sail launch into space atop an unmanned H-2A rocket on May 20 (U.S. Eastern Time) from Tanegashima Space Center in Japan. It was early morning Friday, May 21 at the Japanese launch site.
Credit: JAXA

A powerful new Japanese spacecraft and experimental solar sail blasted off together on Thursday (Eastern Time) to start a six-month trek to explore Venus and cosmic parts beyond.

One mission is aimed at uncovering the secrets of Venus and its cloud-covered surface, while the other could become the first interplanetary solar sail to successfully fly in space. The Japan Aerospace Exploration Agency (JAXA) is backing both spaceflights.

A Japanese H-2A rocket lifted off with the Venus Climate Orbiter, named Akatsuki, as its main payload at precisely 5:58:22 p.m. EDT (2158:22 GMT). ?By coincidence, it was early Friday morning local Japan time at the Tanegashima Space Center at the time of launch.

The Akatsuki spacecraft's name means "Dawn in Japanese. If all goes well, it should arrive at Venus in December.

JAXA hoped to launch Akatsuki and its Ikaros solar sail companion earlier this week, but low clouds and foul weather prevented a liftoff initially scheduled for Tuesday morning (local Japan time).

Unveiling Venus

Akatsuki has set sights on a planet that scientists consider as Earth's moodier, more hellish twin.

One of the main goals is to understand the "super-rotation" of the Venus atmosphere, where violent winds drive storms and clouds around that planet at speeds of more than 220 mph (360 kph), some 60 times faster than the planet itself rotates.

"Akatsuki is the first 'meteorological satellite' of a planet other than the Earth," said Seiichi Sakamoto, director for space science outreach at JAXA's Institute of Space and Astronautical Science. "Detailed study of Earth's sister planet will provide us with breakthroughs in the field of atmospheric science."

Solar sail rides shotgun

Japan's new solar sail, named Ikaros (Interplanetary Kite-craft Accelerated by Radiation Of the Sun), also hitched a ride as one of five smaller secondary payloads built by private universities and corporations.

The solar sail craft will take the same starting trajectory as Akatsuki, but is only scheduled to pass the orbit of Venus during its ambitious three-year journey to the other side of the sun.

Ikaros is designed to rely only upon the pressure of sunlight to push it along, but it also carries thin film solar cells embedded within its kite-like frame that can generate electricity. Such a design might allow future spacecraft to draw electricity for ion-propulsion engines, even as they also use the solar sail for backup — not unlike a sailing boat that also uses a solar-powered engine.

The mission launch involved an unusual maneuver for the H-2A rocket, which typically separates its main payload before the smaller payloads.

"This time we separated three piggyback satellites before Akatsuki," Sakamoto told SPACE.com. "This is new to H-2A."

A JAXA publicity campaign to send names and messages to Venus has received more than 260,000 names and messages from around the world, according to Sakamoto. Akatsuki's study of Venus is planned to last at least two years after it enters the planet's orbit.

The Japanese space agency also launched a new space freighter late last year aboard an H-2B rocket, which represents the newer and bigger descendant of the H-2A rocket that kicked off the Venus mission.