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Japan’s Akatsuki spacecraft is finally in orbit around Venus

The probe was originally supposed to be in orbit five years ago

JAXA/Akihiro Ikeshita

If all went well, Japan’s Akatsuki spacecraft is now in orbit around Venus — five years later than its engineers originally planned. However, it will be a few days before the Japanese mission officials can confirm their back-up maneuver actually worked.

Akatsuki, launched in May 2010, was designed to study the atmosphere around Venus, which rotates much faster than the planetary surface underneath. But when the spacecraft attempted to ignite its main engine and enter the planet’s orbit, things went wrong. Salt had accumulated in a valve between a tank of pressurized helium and a fuel tank, cutting off the flow of fuel to the main engine, and causing a nozzle in the propulsion system to break. So instead of putting itself on a path around Venus, the craft went spinning around the Sun.

Instead of putting itself on a path around Venus, the spacecraft went spinning around the Sun

Since then, engineers at the Japan Aerospace Exploration Agency (JAXA) have been figuring out ways to recover the mission. The agency had to wait five years for Akatsuki to orbit the Sun and catch up with Venus again, and it also needed an alternative way to propel the spacecraft into the planet’s orbit. The main engine was dead, so Jaxa dumped more than 140 pounds of its fuel into space to make the craft easier to maneuver. As an alternative the engineers turned to the spacecraft’s thrusters — small engines on the probe normally used to make adjustments in position. JAXA ignited four of the eight thrusters on Akatsuki for about 20 minutes to get the craft into an elliptical orbit around the planet.

JAXA will announce on Wednesday whether or not the maneuver was successful; the agency is expected also to provide details about the spacecraft’s orbit. If the thruster burn worked, Akatsuki will be on a very different path than it was supposed to take back in 2010. Originally, the spacecraft's orbit was meant to range from 186 to 49,700 miles above Venus and last for 30 hours. With the new moves, the spacecraft won’t be as close — it may be more than six times farther at 310,000 miles above Venus, and orbiting over a period as long as 14 to 15 days. Eventually, JAXA plans to fire Akatsuki's thrusters again to get it closer to the planet, but the probe still will be farther out than originally intended. Because of the difference in orbit, the probe will likely collect less data than JAXA had initially planned.