Akatsuki Put into Venus's Orbit Successfully: A Significant Step Forward in the History of Planetary Exploration

Cutting edge technology supporting Akatsuki

(C) Japan Aerospace Exploration Agency (JAXA)

At around 9 a.m. on December 7, 2015, Japanese time, Akatsuki (PLANET-C) decelerated as it approached Venus and entered into its orbit successfully for the first time in Japan’s planetary exploration history.

A Japanese probe Akatsuki was launched following the Mars climate orbiter Nozomi (PLANET-B), with a mission of unlocking the mysteries of the atmosphere of Venus. Venus is called the earth’s twin in terms of size and distance from the Sun. The major mission of Akatsuki is to obtain a clue for elucidating the origin of the planet Earth and the global climate change.

Actually, Akatsuki, launched from the Tanegashima Space Center in May 2010, failed to enter into Venus’s orbit due to a failure of the main engine. Since then, the probe had been gradually correcting the orbit by using a small attitude control engine while circling the Sun, and finally it has entered into Venus’s orbit successfully.

Fujitsu is responsible for three systems including "orbit determination system"

In addition to the Japan Aerospace Exploration Agency (JAXA), many Japanese companies are involved in the mission of Akatsuki. Among them, Fujitsu plays three important roles in: the orbit determination system, real-time monitoring system for orbit control, and ground data transmission system for satellite communication.

The orbit determination system is a ground data processing system for estimating the position and speed of Akatsuki flying in space. This system plays an important role because the probe’s flight plan is determined based on the output of the system. Fujitsu has been involved in the program from studies prior to the launch to the operation on the orbit through the construction, development, and operation of the system that provides orbital data, vital data for carrying out the mission. At JAXA, they carefully check data obtained through daily communication between Akatsuki and the antenna and process data based on this system, instead of automating the determination and operation of the orbit.

The real-time monitoring system for orbit control (maneuver monitoring (Note 1) system) monitors changes in Akatsuki’s speed during orbit control in real time and provides information. Whether additional orbit control was needed was determined when putting Akatsuki in the orbit around Venus based on the monitoring results from this system.

The ground data transmission system is used to connect between earth stations for communication between Akatsuki and the Institute of Space and Astronautical Science’s space operation center. Fujitsu is in charge developing and operating the data transmission system connecting the Space Operation Center in Sagamihara, Kanagawa Prefecture, the Uchinoura Space Center, in Kagoshima Prefecture, and the Usuda Deep Space Center in Nagano Prefecture.

(Note 1) A display system to display differences between estimates based on 2-way Doppler measurements (that measure a difference in the frequencies of a signal from the earth to a satellite) and momentary measurements obtained in orbital correction in real time. It enables highly accurate measurement processing to be carried out using slight acceleration.

Fujitsu’s ICT supports state-of-the-art space science: Akatsuki, Hayabusa 2, and a Mercury probe

It is expected that observation of the atmosphere under Venus’s cloud layer and Venus’s ground by Akatsuki will lead to the clarification of the origin and climate change of the planet Earth and other several mysteries. Akatsuki’s mission also includes investigating whether there is lightning discharge or volcanic activity on Venus, for which there is no definitive evidence.

Fujitsu has been involved in developing and operating orbit determination systems, from the Moon probe mission at the dawn of Japan’s space age through to the present. Going forward, Fujitsu will continue to support with the power of ICT state-of-the-art space science, including Hayabusa 2, which successfully performed a flyby of the Earth recently, and BepiColombo, an ongoing Mercury probe project, in addition to Akatsuki.