Why Japan's probe to Venus has been so full of drama

The Japanese space agency is trying for a second time in five years to send the same spacecraft into orbit around Venus.

A computer simulated view of Venus is seen, made from mosaics of images captured by NASA's Magellan spacecraft.

Five years and one day ago, careening toward the atmosphere of a nearby planet, a Japanese spacecraft spun off course, and for a short time, the mission appeared doomed.

Akatsuki, a probe launched by the Japan Aerospace Exploration Agency (JAXA) to orbit Venus and explore its hostile atmosphere, was ready in December 2010 to begin orbiting the second planet when disaster struck. A spike in temperature to its main engine, believed to be caused by a choked fuel valve, caused the probe to spin and veer off course, and the space agency missed, by a matter of minutes, the opportunity to put its spacecraft in Venus orbit.

For a time, JAXA scientists had a functioning spacecraft with five cameras aboard careening uselessly through space. Until now. Five years later, the probe has come Venus’s way again, and this time, the space agency is ready: Akatsuki executed its backup plan on Sunday, and now the space agency is waiting for data from the probe to show if that plan actually worked.

Getting there was a feat.

Even though the main engine is damaged, JAXA realized it could still rely on its working maneuvering thrusters to reach orbit. Yesterday, five years to the day after it missed, Akatsuki fired up four of its Reaction Control System thrusters for 20 minutes, enough time to get into orbital position, and the longest burn ever conducted by the vehicle’s small thrusters, Space.com reports. While the maneuvers appear to have done no harm to the probe, it will be another couple of days before JAXA has data to tell if Akatsuki is actually in orbit.

"The orbiter is now in good health," JAXA officials wrote in a mission update Sunday. "We are currently measuring and calculating its orbit after the operation. It will take a few days to estimate the orbit; thus we will announce the operation result once it is determined."

In addition to the hack that may save the mission, the plan required Akatsuki, which means “dawn” in Japanese, to far outlive its two-year life expectancy. The spacecraft also skirted dangerously close to the Sun on its loop back to Venus, which it survived despite not being specifically built for such a trip.

Akatsuki – also known as the Venus Climate Orbiter – cost $300 million and launched in May 2010 with a mission to study the atmosphere of Venus, including its cloud and weather patterns, with scientists hoping to better understand why the planet is so much hotter and more barren than Earth.

If Akatsuki reaches orbit, it will be the first spacecraft to study Venus since the European Space Agency’s Venus Express reached its mission’s end last year and completed a planned crash into the atmosphere.

This second shot at orbit will be longer than originally planned — lasting for 8 or 9 days, compared to the 30 hours allotted in 2010. That is, if Sunday's maneuver worked. JAXA officials said that if successful, the probe should still be able to accomplish most of its mission goals.

Gizmodo reports that during a press conference on Sunday, project manager Masato Nakamura said, “We have to wait another two days to confirm the orbit. I am very optimistic. It is important to believe in success!”

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