Our only mission to Venus may have gone dark

Enlarge / Processed image of Venus captured by the Akatsuki spacecraft.

JAXA/ISAS/DARTS/Kevin M. Gill

JAXA, the Japanese space agency, confirmed on Wednesday that it had lost communication with its Akatsuki spacecraft in orbit around Venus.

In its update, the space agency said it failed to establish communications in late April after the spacecraft had difficulty maintaining its attitude. This probably means that there is some kind of problem with the spacecraft’s thruster that prevents it from being able to steer toward Earth.

“Since then we have implemented various measures to restore service, but communication has not yet been restored,” the agency stated. “We are currently working to reestablish communication.” JAXA added that it will announce further actions, if any, as soon as they have been decided.

The possible loss of the Akatsuki spacecraft, a relatively small 320kg probe with a mass slightly larger than that of a dishwasher, would be notable for a couple of reasons. First, it would mark the end of a brave mission that overcame a major failure a decade ago when attempting to enter orbit around Venus. Second, it would mean losing humanity’s only spacecraft currently orbiting Venus.

A failure to orbit

The Akatsuki mission launched aboard an H2-A rocket in 2010 and was Japan’s first interplanetary mission in more than a decade after the country’s failed Nozomi mission to Mars. However, after reaching orbit, the spacecraft’s main engine failed to successfully lower its orbit. The engine burned for about three minutes instead of 12, leaving the spacecraft orbiting the Sun instead of Venus.

Over time, Japanese mission planners developed a new option for entering orbit around the planet. The main engine did not work, so to reduce the mass of the ship they threw 65 kg of oxidizer overboard. With the spacecraft’s mass reduced, operators planned to use Akatsuki’s four hydrazine-powered attitude control thrusters to insert the vehicle into an elliptical orbit around Venus.

In the end, the plan worked. The spacecraft was placed into a 10-day orbit around the planet, with a closest approach of about 400 km. This allowed scientists to begin taking data in 2016 about the planet and its atmosphere. In 2018, the mission’s lifespan was extended and it continued collecting data until this spring.

Only eyes on Venus

Akatsuki is currently the only operational spacecraft on Venus. There are two solar orbiters, one built by NASA and the other by the European Space Agency, that intermittently pass Venus for gravitational assistance, but they are not studying the planet in any meaningful way. Apart from this, we are blind to the events of the planet closest to Earth in our Solar System.

Half a dozen missions are in development, but none of them have a firm launch date for the end of this decade.

Additionally, there is a spacecraft on the way to Venus: the ambitious European BepiColombo spacecraft. It launched in 2018 with a mission cost of $2 billion, and there is a lot riding on the spacecraft. However, there are doubts about BepiColombo after its solar-electric propulsion system was unable to operate at full power. A couple of weeks ago, one of the people responsible for the spacecraft told Ars that they were still studying the feasibility of reaching orbit around Venus with this reduced propulsive capacity.

Hopefully the answers to that question and Akatsuki’s ultimate fate will come soon.

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