Japanese Akatsuki Probe Fails To Enter Orbit Around Venus
TOKYO — Japan’s Akatsuki spacecraft sped past Venus on Dec. 7 without entering orbit, but mission planners hope to attempt orbital insertion again in six years when the 25.2 billion yen ($300 million) probe swings back around.
Akatsuki, the 500-kilogram spacecraft formerly known as the Venus Climate Orbiter, began its scheduled orbital insertion burn at 8:49 a.m. Tokyo time as it approached within 550 kilometers of the planet. Japan Aerospace Exploration Agency (JAXA) officials were at a loss Dec. 8 to explain exactly what went wrong, but they said it appears Akatsuki’s planned 12-minute burn was cut at least 10 minutes short when the spacecraft switched itself into safe mode for unknown reasons.
The first indications of a problem came as Akatsuki’s expected 22-minute communications blackout stretched to more than an hour and a half before JAXA was able to re-establish contact with the spacecraft. Officials initially hoped Akatsuki was merely in an unexpected orbit, but they soon confirmed the probe was speeding beyond Venus.
JAXA said Dec. 8 that its executive director, Junjiro Onoda, will lead the failure investigation. At a press conference the same day, both Onoda and Akatsuki Project Manager Masato Nakamura apologized for the mission going awry.
“I am really sorry that we were unable to fulfill the nation’s expectations,” Nakamura said.
The failure echoes that of Japan’s Nozomi Mars mission, which in 1998 suffered a thruster failure that delayed the orbiter’s arrival at the red planet by more than four years. Engineers were unable to get the badly battered and aging probe into Mars orbit.
JAXA calculates that Akatsuki will be back in position between December 2016 and January 2017 to make a second attempt to enter orbit around Venus.
Engineers foresee no problems reprogramming the spacecraft since its high-gain antenna is still working. But Nakamura said it is not clear whether the spacecraft’s batteries, which have a four-year design life, will last until 2017. Nor is it known whether Akatsuki has enough fuel remaining for a second orbital insertion burn and at least one midcourse correction probably needed to make it back to the planet, Nakamura said. A best-case scenario, he said, forecasts the probe still has 80 percent of its fuel remaining.
In the meantime, he said, JAXA will minimize stress on the batteries by keeping Akatsuki’s solar panels oriented toward the sun as much as possible.
“I believe it’s highly likely we’ll be able to make it next time,” Nakamura said.
Akatsuki is designed to study volcanic activity on Venus, provide data on its thick cloud cover and climate, and investigate whether the planet has lightning. The spacecraft was launched in May aboard an H-2A rocket.