Spaceflight Insider

Second time’s a charm: Japanese Akatsuki spacecraft enters Venus orbit

Akatsuki in Venus orbit

An artist’s rendering of Akatsuki entering around Venus. Image Credit: JAXA

After the first try ended in failure five years ago, Japan’s first Venus Climate Orbiter, Akatsuki, successfully entered orbit above the planet Venus on Monday, Dec. 7. Japan is only the fourth entity, behind Russia, the United States, and the European Space Agency (ESA), to place a spacecraft around Earth’s nearest planetary neighbor.

At 8:51 a.m. JST (23:51 GMT on Dec. 6), the spacecraft’s attitude control engines fired to insert the probe into orbit. According to the Japan Aerospace Exploration Agency (JAXA), the burn lasted for approximately 20 minutes, as scheduled and the spacecraft is now in good health. The probe’s exact orbit is now being measured and calculated. It could take mission controllers a few days to determine it precisely.

Japanese mission controllers cheer Akatsuki's insertion into Venus orbit.

Japanese mission controllers cheer Akatsuki’s insertion into Venus orbit. Photo Credit: JAXA

“In fact, now that the spacecraft is in orbit, the attitude of the spacecraft has to be continuously updated,” said Sanjay Limaye, Senior Scientist at the Space Science and Engineering Center of the University of Wisconsin-Madison. “The commands will be generated manually and uploaded until the orbit is known better.”

Limaye witnessed the orbital injection operations at the Institute of Space and Astronautical Science (ISAS) located in Sagamihara, Japan.

Akatsuki is now moving with respect to Venus at only slightly more than 1 kilometer (about .62 miles) per second and is about 250,000 kilometers (155,343 miles) away from Venus,” Limaye said.

Akatsuki, which means “dawn” in Japanese, was originally known as the Venus Climate Orbiter (VCO) or Planet-C. It was designed to study the atmosphere of Venus. The spacecraft was launched on an H-IIA 202 rocket from the Tanegashima Space Center on May 20, 2010.

The first attempt to insert Akatsuki into Venusian orbit failed due to an engine malfunction that occurred on Dec. 6, 2010. The spacecraft was then sent on a five-year trip around the Sun to re-align for another attempt at orbital insertion. Finally, in August 2015, trajectory correction maneuvers placed it back on track for a rendezvous with Venus.

“At last, we’ve achieved what should have been done five years ago,” said Masato Nakamura, the manager of the Akatsuki project, in a news conference after the successful orbit injection.

JAXA Japan Aerospace Exploration Agency Akatsuki spacecraft JAXA image posted on SpaceFlight Insider

Artist’s depiction of the Akatsuki spacecraft. Image Credit: JAXA

“I didn’t expect it to be so hard,” said Chikako Hirose of JAXA, a specialist in orbital determination for space debris. He was assigned to a team charged with calculating and adjusting the trajectory for inserting the Akatsuki orbiter.

“It’s been a long time since the first attempt five years ago, but those years have passed quickly. It was a once-in-a-lifetime experience,” Hirose said.

Akatsuki is a 4.8 by 3.4 by 4.7 feet (1.45 by 1.04 by 1.44 meters) box-shaped spacecraft with a mass of some 1,141 pounds (517.6 kilograms). It features two solar arrays, which provide more than 700 Watts of power. It is equipped with six scientific instruments: the Lightning and Airglow Camera (LAC), an ultraviolet imager (UVI), a longwave infrared camera (LIR), a 1-micrometer camera (IR1), a 2-micrometer camera (IR2), and the radio science (RS) experiment.

The spacecraft’s main goal is to unveil the mechanism of “super-rotation” of Venus atmosphere by continuous high-resolution mapping similar to meteorological satellites orbiting the Earth.

The probe will obtain meteorological information about Venus by globally mapping clouds and minor constituents successively with four cameras at ultraviolet and infrared wavelengths, detecting lightning with a high-speed imager, and observing the vertical structure of the atmosphere with radio science techniques.

Additional targets of the mission are the exploration of the surface and the observation of zodiacal light.

Akatsuki is Japan’s first planetary exploration mission since the Nozomi probe, which launched in 1998 and was sent to Mars (it failed to enter Martian orbit in 2003).

Artist's rendering of the Akatsuki spacecraft entering Venus orbit.

An artist’s rendering of Akatsuki entering Venus orbit. Because the spacecraft’s main engine was no longer working, it was commanded to use its attitude control engines – something it wasn’t designed for. Image Credit: Go Miyazaki


Tomasz Nowakowski is the owner of Astro Watch, one of the premier astronomy and science-related blogs on the internet. Nowakowski reached out to SpaceFlight Insider in an effort to have the two space-related websites collaborate. Nowakowski's generous offer was gratefully received with the two organizations now working to better relay important developments as they pertain to space exploration.

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