JAXA officially ends the Akatsuki probe mission after more than a decade of studies on Venus

Agência of Exploração Aeroespacial of Japão (JAXA) announced the formal termination of operations of the Akatsuki probe, a milestone in the country’s interplanetary exploration. The decision, made official on September 18, 2025, occurred after the loss of communication with the equipment in April 2024, when problems in the attitude control system prevented contact from being reestablished.

Launched in May 2010, the mission’s main objective was to unravel the mysteries of the dense and fast atmosphere of Vênus. Akatsuki became the first Japanese probe to orbit another planet, providing crucial data for more than eight years and overcoming a critical failure that nearly compromised its entire scientific journey.

The information collected by the probe resulted in more than 170 scientific articles, which transformed the understanding of Venusian atmospheric dynamics. The legacy of Akatsuki will continue to influence future missions to the second planet of Sistema Solar, serving as a basis for new projects by space agencies around the world.

A journey of overcoming in space

The trajectory of the Akatsuki was marked by challenges and a remarkable demonstration of Japanese engineering resilience. Lançada on May 20, 2010, the probe reached Vênus in December of the same year, but a failure in the main engine during the orbital insertion maneuver prevented it from being captured by the planet’s gravity.

After the incident, the probe entered an orbit around Sol, where it remained for five long years. During this period, the JAXA team worked tirelessly to develop an alternative plan. The solution found was to use the secondary thrusters, originally intended for attitude control, to carry out a new orbital insertion attempt.

In December 2015, the alternative maneuver was successfully executed, and Akatsuki finally entered an elliptical, elongated orbit around Vênus. Essa new trajectory, although not originally planned, proved to be advantageous, allowing observations of the planet from different distances and angles, which significantly enriched data collection.

The mission operated continuously for more than eight years, a period much longer than initially planned. The loss of contact in 2024 was attributed to degradation of control system components, ending one of the most impressive recovery stories in modern space exploration.

Akatsuki’s eyes on Vênus

To investigate the complex atmosphere of Vênus, the Akatsuki probe was equipped with a suite of six high-precision scientific instruments. Cada one was designed to observe the planet in different wavelengths, from ultraviolet to infrared, as well as radio waves, allowing the creation of a detailed three-dimensional map of the structure and dynamics of Venusian clouds. Entre the equipment, two infrared cameras stood out that measured the temperature and movement of clouds at different altitudes, revealing convection patterns and heat distribution.

Câmera of Imagem Ultravioleta (UVI) was instrumental in tracking a mysterious UV-absorbing component in the atmosphere, as well as mapping the distribution of sulfur dioxide, a gas important to atmospheric chemistry. Outro crucial instrument was the Oscilador Ultra-Stable, which generated a radio signal to probe the vertical structure of the atmosphere, measuring temperature and density profiles with extreme accuracy. Combining data from all instruments allowed scientists to gain an unprecedented view of Vênus’s meteorology, from high-speed winds to electrical phenomena.

Unraveling Venusian super-rotation

One of Akatsuki’s greatest contributions was providing essential data to explain the phenomenon of Vênus’s atmospheric super-rotation, where the atmosphere circles the planet about 60 times faster than the rotation of the solid surface. Winds in the upper cloud layer reach speeds of more than 360 kilometers per hour, a puzzle that has puzzled scientists for decades. The probe’s continuous observations made it possible to identify the mechanisms that sustain this extreme circulation. The mission revealed that atmospheric waves, such as thermal tides generated by daytime solar heating, and gravity waves, originated by the interaction of wind with surface topography, transport momentum and energy from the lower to the upper layers of the atmosphere. Esse vertical energy transport acts like an engine, accelerating winds at higher altitudes and maintaining super-rotation. Analysis of data from Akatsuki confirmed that the combination of these different types of waves and the associated turbulence are primarily responsible for sustaining this relentless wind regime, a process that does not occur in a similar way on any other rocky planet on Sistema Solar.

The biggest mountain wave in the solar system

Shortly after its arrival at Vênus in 2015, Akatsuki made a surprising discovery when it recorded an immense arch-shaped structure in the planet’s clouds. The Essa feature, thousands of kilometers long, remained stationary over the mountainous region of Aphrodite Terra, contrasting with the high-speed winds that surrounded it.

Further analysis confirmed that it was a gravity wave, also known as a mountain wave. The phenomenon is generated when the air flow in the lower atmosphere is forced to rise when passing through a topographic elevation, such as a mountain range, creating a ripple that propagates to the upper atmospheric layers.

The wave observed in Vênus is the largest ever identified in Sistema Solar, demonstrating a strong connection between the planet’s surface and its upper atmosphere. Essa discovery proved that Venusian topography has a direct and significant influence on global atmospheric circulation, something that previous models did not predict so clearly.

Wind Flows and Weather Patterns

The data collected by the probe allowed the identification of a high-speed equatorial jet in the middle and lower cloud layers of Vênus. Este wind flow, concentrated in the equatorial region, plays a fundamental role in transporting heat and momentum around the planet, influencing the formation of vortices and other climatic structures.

The three-dimensional observations provided detailed maps of atmospheric circulation, revealing complex variations in wind patterns over time. Esses findings helped explain how temperatures on the surface of Vênus remain relatively uniform despite the planet’s slow rotation and differences in heating between the day and night sides.

Signs of electrical activity in the atmosphere

In 2020, one of Akatsuki’s instruments detected a possible lightning signal on the night side of Vênus. Although the observation is not considered definitive, it reinforces the hypothesis that there is electrical activity in the dense Venusian atmosphere, a topic of scientific debate for many years.

The scientific legacy of the Japanese mission

The Akatsuki mission leaves an invaluable legacy for planetary science. By providing the longest and most detailed set of data on the meteorology of Vênus, the probe allowed scientists to study the planet’s climate variations over several years, something that had never been done in such depth.

The information collected is fundamental for comparative planetology, helping to understand why Vênus and Terra, despite their similarities in size and composition, followed such distinct evolutionary paths. The success of the mission, especially its recovery after the initial failure, solidified Japão’s position as a powerhouse in space exploration.