Now Orbiting Cloud-Shrouded Venus, Akatsuki Sends New Images

It’s not every day you hear about a troubled spacecraft making a desperate attempt to cling to a planet — for the second time.

After missing its first chance to orbit Venus, Japan’s Akatsuki spacecraft circled the sun for five long years, waiting for the right time to try again. That moment came on Dec. 7, a half-decade to the day after a broken nozzle sent Akatsuki hurtling toward the sun instead of falling into the gravitational clutches of Earth’s sister planet. But with its large, main engine crippled, the spacecraft needed another way to slip into orbit. That responsibility went to four smaller thrusters that are normally used to adjust where the spacecraft is pointing; for 20 minutes they fired, nudging Akatsuki onto a course for capture as it skimmed the Venusian cloud tops.

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This image, illustrated before Akatsuki took its second shot at Venus, depicts a scene very much like what happened as it fired its thrusters on Dec. 7. “I was deeply moved to realize it,” says Akatsuki’s project manager Masato Nakamura. (Akihiro Ikeshita/JAXA)

And then the team commanding the spacecraft, at the Japan Aerospace Exploration Agency, waited. Shifts in the radio waves Akatsuki uses to communicate with Earth would indicate whether the spacecraft had changed course. If it hadn’t, there was a small window in which the team could try again, using an alternate set of thrusters. And if that didn’t work? Well, no one wanted to think about that. The third time might be the charm on Earth, but in space, getting even a second chance is exceedingly rare.

An hour later, scientists shared the exciting news: “It is in orbit!!” reported Sanjay Limaye, of the University of Wisconsin-Madison, who was with the team in Sagamihara, Japan. The question was, which orbit? Was it stable? Could the team talk with the spacecraft? Is Akatsuki healthy?

It would take two days of analysis to work out the precise path Akatsuki is taking around the cloud-shrouded world. On Dec. 9, scientists announced that the orbit is a bit more stretched out than anticipated, though it’ll do. Now, Akatsuki takes a little more than 13 days to orbit Venus, swinging from 400 kilometers above the planet’s surface out to 400,000 kilometers away. Over the next four months, engineers will reshape the spacecraft’s path so it will complete one trip around Venus in fewer days — and then in April, the real science observations will begin.

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Akatsuki’s current path around Venus, and the one it will slip into for science observations. (JAXA)

For now, the team will be making sure that all the instruments on board the spacecraft are working. After all, Akatsuki was originally designed for a two-year mission in space — an amount of time it has already surpassed while circling the sun. The spacecraft’s extended trip around the solar system brought it closer to the sun than scientists had intended, meaning Akatsuki’s instruments have encountered temperatures a bit warmer than they were designed for.

So far, though, the team says the spacecraft is healthy — and as proof that at least some of the onboard cameras are undamaged by Akatsuki’s sojourn in space, has released three images taken as the spacecraft slipped into orbit (see gallery, above). These are the first closeup images of Venus we’ve seen in a while, and with no new missions to the planet on the schedule, they could be among the first of the last for the foreseeable future.

If all goes well, Akatsuki will hover above the planet for the next two years, peering into the churning, super-rotating atmosphere that whips around Venus faster than the world itself rotates. Once thought to be very much like the Earth, the Venus of today is a hellish wasteland, transformed into a planetary inferno by runaway greenhouse gases. It has the hottest recorded temperature in the solar system (aside from the sun), a young surface that shows signs of recent volcanism, and sulfuric acid clouds that flash with lightning.

But from afar, Venus shines more brightly than just about anything else in the sky. It’s a shimmering, tranquil pinprick of light that has bewitched astronomers, poets and entire cultures for millennia — and now, after a drama of interplanetary proportions, it has a plucky little robot friend once again.

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