Five Years for a Second Chance: Japan's Akatsuki Probe Attempts Venus Again

It's waited exactly five years for a second chance at the prize and now has an opportunity to finally complete its mission. The Japan Aerospace Exploration Agency's (JAXA) Akatsuki probe is now allowed another attempt to begin circling Venus.

Exactly five years ago from December 6, Akatsuki failed to enter Venus' orbit because of a problem with its main engine. Because the engine failed during a critical orbit-insertion burn, the spacecraft passed the planet and went off into space, eventually orbiting around the sun.

JAXA's mission engineers determined the problem shortly after the failure and have developed alternate methods of entering the orbit, but have had to wait five years to try again. Since Akatsuki's main orbit maneuver engine (OME) has been declared dead, it will use its smaller altitude control thrusters, called reactor control system (RCS) thrusters, in 20 minute burn segments to control its trajectory. Discovery News adds, the RCS thrusters should be able to get the probe into orbit, especially since the probe is lighter after discarding the unusable OME fuel.

Akatsuki, reported by JAXA as still in good condition, will start the effort at 7AM, December 7, Japan Standard Time (5PM, EST).  Unfortunately, as Space.com reports, JAXA officials have stated that JAXA's mission control probably won't know for a few days if the operation was successful.

It will be the last chance for the probe to enter Venus' orbit, if it fails, it has no more opportunities to try again. With USA Today, JAXA's Takeshi Immamuara explains, "During this operation, we will use all of the remaining fuel. We have no other chance."

The golf-cart sized Akatsuki was originally launched May 2010 and was designed to find information on how Venus, Earth's "sister planet", became so hot and seemingly so inhospitable to life. Akatsuki was supposed to enter a 30-hour orbit around Venus, and then study the planet's clouds, weather and atmosphere for at least two years.

Despite taking longer to complete its mission, Akatsuki should still be able to complete the majority of it, but there are some adjustments. Because of the change in how it will enter Venus' orbit, the probe will be analyzing the planet from a farther distance, with the new target orbit becoming a time period of eight or nine days instead of 30 hours. The distance to the planet from the probe is now 300,000 - 400,000 kilometers away (186,000 - 250,000 miles) instead of the original goal of 80,000 kilometers (50,000 miles). The duration of the study is now dependent on the remaining life of the batteries, so it is uncertain if it can endure for the original two years.

Since the end of the European Space Agency's Venus Express mission, which went into a death dive into the planet's hot atmosphere, the $300 million probe, whose name means dawn in Japanese, will be Earth's only spacecraft around Venus. You can send the probe and JAXA support by tweeting with the hashtag #akatsuki.