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Mar. 10, 2015 - Updated 04:16 UTC

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Final Chance at Venus

Tomoko Kamata

Dec. 7, 2015

Japan's space agency is making a second attempt at putting a space probe into orbit around Venus. Scientists hope the Akatsuki probe will help them learn about the nature of climate change.

Venus is the brightest celestial body in the solar system, aside from the sun and moon. An earlier attempt to launch Akatsuki into its orbit failed, and the latest attempt is the last chance for success.

Engineers at the Japan Aerospace Exploration Agency had high hopes Monday when they fired up engines on the well-traveled probe. They are giving it one final shot five years after their initial disappointment.

"We have great expectations that the probe will enter orbit as planned,” says Akatsuki project manager Masato Nakamura.

Venus is often referred to as Earth's sister-planet as they are the same size and age. But their environments are very different as Venus' atmosphere is mainly carbon dioxide and has a surface temperature of about 470 degrees Celsius. Scientists say exploration may provide clues to understanding climate change on Earth.

Akatsuki, which translates to “dawn” in English, was launched in 2010 in a mission to explore the climate of Venus. Its main engine broke down before it could enter the planet’s orbit and the probe has spent the last five years circling the sun. During that time, engineers devised a new plan.

They are using four small engines to propel the probe, and have plotted a new course after considering thousands of options. After Monday's maneuver, a JAXA official says he is relieved to have overcome the most difficult hurdle.

Challenges do remain, and there is a concern the probe's engines may not have enough power to achieve orbit. JAXA will know if its plan has worked in about two days.


NHK World's Kazuaki Hirama joined NEWSROOM TOKYO anchors Sho Beppu and Aki Shibuya is the studio to discuss the Akatsuki probe’s prospects for success.

Beppu: How difficult was this to accomplish?

Hirama: Well first of all, it was unprecedented for a probe with its main engine down to restart with its auxiliary engines. The engines used today were designed to control the direction of the probe, not to give thrust. Using them to bring the probe into orbit was considered a tall order. That's why the engines needed to be fired for more than 20 minutes to get enough thrust. In addition, the probe has been travelling around the sun for so long that the temperature on its surface is higher than it was designed for. If the temperature continues to rise, the structure could break. Officials at Japan's space agency said today they were impressed they'd succeeded in restarting the engine. Akatsuki project manager Masato Nakamura said the probe was sturdier than he expected. He added that it was amazing to find there were no major structural problems with the spacecraft.

Shibuya: Why is the agency eager to restart the mission despite the difficulties?

Hirama: Scientists believe that studying Venus will help them understand our own planet. Venus and Earth are often called "sister planets," as their size and the distance from the sun are almost the same. The temperature and atmospheric pressure are comparable to the Earth's, about 50 kilometers above Venus's surface. But the conditions at the surface are totally different. On the surface of Venus, the temperature is around 500 degrees Celsius. The planet is surrounded by a layer of gas that's mostly carbon dioxide. There's also a phenomenon called "super-rotation." Winds blow at about 350kph, faster than Venus rotates. Officials at the space agency say they hope to find out what creates those climate patterns and draw lessons from them.

Beppu: If the surface of these two sister planets is so different, why is it so important for us on Earth to study it?

Hirama: The project could shed light on how to fight climate change. Many scientists believe Venus was similar to Earth billions of years ago, with lower temperatures and even water on the surface. They say carbon dioxide may have trapped the heat, causing temperatures to rise and evaporating the water. So learning about the greenhouse effect on Venus could teach us how to deal with it on Earth. Many experts hope the project could be a step toward keeping our global environment healthy.

Beppu: It sounds like the success or failure of this project could draw a lot of attention internationally, particularly as the world's attention is focused on the climate talks in Paris.

Hirama: Scientists around the world are watching this attempt very closely. That's because, some scientists in Europe were eager to collaborate with the Akatsuki team to explore Venus. When the European Space Agency launched a probe called "Venus Express" in 2005, they wanted to work with Japan. But "Venus Express" finished its mission last year without achieving that collaboration. A Japan space agency official said they felt a responsibility to restart the project and analyze data from both the European and Japanese probes. Restarting the secondary engines is just one step in the project. The real success will come if the Akatsuki probe is able to finally start transmitting data about Venus, sometime around next April.