NASA’s Juno Probe ‘Fainted’ Twice During Flybys of Jupiter, But Is Now All Right

On April 4, 2025, NASA’s Juno probe went into safe mode twice, where all scientific instruments stop working. On that day, Juno was making its 71st close approach to the gas giant. Jupiter is surrounded by powerful radiation belts, so the shutdown of electronics under their influence is an expected event. After moving away from the planet, Juno returned to normal operation and is ready for another approach to Jupiter on May 7.

An artist’s impression of NASA’s Juno probe with Jupiter in the background. Image Credit: NASA

During its time in the Jupiter system, Juno entered safe mode four times. The first time was in July 2016, during its second approach to the planet. The second time, the electronics failed in 2022, during its 39th approach. And finally, on April 4, 2025, the safe mode command was triggered twice more: one hour before the closest approach to Jupiter and 45 minutes after passing the point of closest approach.

In all four cases, Juno’s electronics functioned as expected. The scientific equipment was automatically switched off, and the communications antenna was pointed at Earth to establish the most reliable channel with the control center. At the same time, the device began checking its own power and control subsystems.

The mission team has restored high-speed data transmissions from Juno, and the spacecraft is currently running diagnostics on its flight software. Over the coming days, the team will be busy transmitting engineering and science data collected before and after the probe entered safe mode to Earth.

Infrared image of Io’s south pole as NASA’s Juno probe flew by on December 27, 2024.

During its approach to Jupiter on May 7, the probe will also pass relatively close to Io, Jupiter’s volcanically active moon. The flyby will take place at an altitude of 89,000 km. Since Io is always full of surprises – it is the most volcanically active celestial body in the solar system – the probe will be able to make valuable observations that will also not go unnoticed.