Abstract
This paper describes on-orbit operations of a power system for Japan’s Venus explorer Akatsuki. It was launched on May 20, 2010, and approached Venus on December 7, 2010, but orbit insertion failed because of a propulsion system malfunction. After the failure, the spacecraft stayed on an orbit nearer to the sun than Venus for 5 years before successfully entering an orbit around Venus in 2015. Telemetry data that show radiation degradation of the solar arrays, and here analytical results by the relative damage coefficients method are presented. The capacity loss of the batteries was successfully suppressed by lowering the state of charge and temperature. We plan to extend the mission period from 4.5 years to longer than 9 years to obtain more fruitful scientific results.
Highlights
The state of charge (SOC) was reduced from 41% to 30% and the temperature was lowered from 10 °C to 0 °C, based on the capacity required when the spacecraft recovered from its attitude loss during the failed Venus orbit insertion (VOI)
This paper described the operation of Japan’s Venus explorer Akatsuki
The spacecraft’s orbit insertion failed because of a malfunction in its orbital maneuvering engine (OME), but successfully entered an orbit around Venus using its thrusters for attitude control after orbiting around the sun for 5 years, despite a designed spacecraft life of 4.5 years
Summary
The spacecraft approached Venus as planned on December 7, 2010, but orbit insertion failed because of a propulsion system malfunction. After the failed first orbit insertion, the spacecraft survived on an orbit nearer to the sun than Venus for 5 years. Akatsuki approached Venus on December 7, 2010 after a half year of cruise, and started burning its 500-N-class orbital maneuvering engine (OME) during Venus orbit insertion (VOI). After orbiting the sun nine times over five years, Akatsuki again approached Venus and conducted VOI-R1 by burning its four 23-N-class reaction control system (RCS) thrusters for 1228 s on December 7, 2015.
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