The European Space Agency (ESA) has successfully restored contact with its JUICE (Jupiter Icy Moons Explorer) probe after a communications anomaly temporarily cut off contact. This was a critical recovery, as the spacecraft is now on track for a crucial gravity-assist flyby of Venus on August 31, 2025.
The communications blackout began on July 16, 2025, when the spacecraft failed to check in with ground stations. Engineers at the European Space Operations Centre (ESOC) in Germany feared the probe had entered "survival mode," but the lack of an intermittent signal from a slow-spinning antenna suggested a different problem. After 20 hours of continuous effort and sending "blind commands" to the distant spacecraft, a signal amplifier was successfully reactivated, and contact was re-established.
The root cause of the anomaly was traced to a software timing bug. An internal counter on the spacecraft that resets every 16 months happened to coincide with a scheduled operation to turn on the communication amplifier, causing it to remain switched off and rendering the spacecraft's signal too weak to be received on Earth. ESA has implemented a fix to prevent this from happening again.
With the communications issue resolved, the JUICE team is now focused on the upcoming Venus flyby. This is the second of four planned gravity-assist maneuvers, which are essential for the 6000 kg probe to build up the necessary velocity to reach the Jupiter system. The spacecraft will not be taking any photos of Venus during the flyby, as it must use its large high-gain antenna as a heat shield to protect its sensitive instruments from the intense solar heat.
The JUICE mission, launched in April 2023, is on an eight-year journey to Jupiter. Following the Venus flyby, it will have two more flybys of Earth in September 2026 and January 2029 before its planned arrival at Jupiter in July 2031. Once there, it will conduct detailed observations of Jupiter and its three largest icy moons: Ganymede, Callisto, and Europa, to explore their potential for harboring habitable environments.