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Japanese hack gets space probe back on track

The little engines that could

It took five years of painstaking work but the Japanese space agency has got its Akatsuki probe back on track.

The Japan Aerospace Exploration Agency (JAXA) has confirmed that a careful combination of telematics, testing, and tentative orbital corrections have put the atmospheric probe into orbit around Venus, albeit half-a-decade later than planned.

On December 6, 2010, Akatsuki, a platform designed to monitor the weather systems on Venus and sample its atmosphere, was supposed to have fired its engines for 12 minutes and settled into orbit around the solar system's second planet. But the main engine failed after just three minutes, and the probe went sailing off around the Sun.

Data received from the spacecraft in subsequent years showed the main engine's fuel oxidizer wasn't being fed in properly thanks to a blocked valve, making the engine run very hot. This caused the main engine nozzle to crack and break off, a scenario that was replicated on Earth.

The oxidizer was now useless, so the JAXA team dumped it to lighten the spacecraft. They then started a series of orbital adjustments using the 12 attitude thrusters on Akatsuki, which were low power but could be run from the main hydrazine fuel tank for longer burns to get the probe into position.

"The Japan Aerospace Exploration Agency (JAXA) performed the attitude control engine thrust operation... for its Venus orbit insertion from 8:51 a.m. on December 7 (Japan Standard Time)," the organization reported on Monday.

"As a result of analyzing data transmitted from the orbiter, we confirmed that the thrust emission of the attitude control engine was conducted for about 20 minutes as scheduled. The orbiter is now in good health."

While its final orbital path won't be confirmed until Wednesday, it does seem likely that the probe's five cameras will be able to get useful images of the storm atmosphere on Venus, with vast acidic clouds flashing lightning to the planet's surface.

That does depend on how well the instrumentation has stood up to its prolonged hibernation. Akatsuki was only designed for a mission lifespan of two years, and its mistaken orbit took it much closer to the Sun than it was designed for, which could have cooked some of its instruments.

But it does appear that mankind, once again, has a spacecraft around the planet. In December last year, the European Space Agency crashed its Venus Explorer probe into the planet after eight years of study, and its data will be perplexing planetary scientists for some time to come. ®

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