NASA’s Juno spacecraft has spent the past few months orbiting the largest planet in our solar system, gathering crucial data that could reshape what we know about Jupiter.
But on Tuesday night, something unexpected happened—Juno suddenly entered “safe mode” just hours before a planned flyby, shutting down all of its scientific instruments.
That means no data was collected during this crucial approach, and NASA engineers are now scrambling to understand what went wrong.
Given that Jupiter’s radiation belts are some of the most extreme environments in the solar system, could this mysterious failure be tied to the very forces Juno was sent to study?
Right now, NASA isn’t sure—but here’s what we do know.
Unlocking Jupiter’s Deepest Secrets
Launched in August 2011, Juno finally arrived at Jupiter on July 4, 2016, after a five-year, 1.74-billion-mile journey.
Unlike previous probes, which only conducted flybys, Juno entered a highly elliptical orbit around Jupiter, allowing it to make repeated close approaches.
The plan? To study the gas giant’s atmosphere, magnetic field, and hidden core like never before.
- Every 53 days, Juno swings within 3,000 miles of Jupiter’s cloud tops, gathering data during each pass.
- The goal is to measure Jupiter’s gravitational field, magnetic forces, and deep atmospheric structure to determine how the planet formed.
- Juno is the first spacecraft to get this close to Jupiter’s poles, offering an unprecedented view of the planet’s auroras, jet streams, and deep weather patterns.
The mission has already produced stunning discoveries, including the revelation that Jupiter’s magnetic field is far stronger and more complex than previously thought.
But to keep the discoveries coming, Juno must remain operational—something that was suddenly thrown into doubt this week.
Juno Enters Safe Mode
NASA scientists were eagerly awaiting Juno’s latest close pass on October 19, where they hoped to collect more critical data.
But just 13 hours before its flyby, Juno unexpectedly shut down its instruments and entered safe mode—a built-in fail-safe designed to protect the spacecraft from damage.
Scott Bolton, Juno’s principal investigator, explained that the shutdown appears to be linked to a software issue rather than a hardware failure.
“It looks like the spacecraft’s computer rebooted itself because it detected a condition that was not expected,” Bolton said at a NASA press conference.
While the exact cause remains unclear, NASA engineers don’t believe it was triggered by Jupiter’s intense radiation belts—a major concern for the mission.
Rick Nybakken, Juno’s project manager, pointed out:
“At the time safe mode was entered, the spacecraft was more than 13 hours from its closest approach to Jupiter.
We were still quite a ways from the planet’s more intense radiation belts and magnetic fields.”
In other words, if radiation isn’t to blame, then what happened?
Is Juno in More Danger Than NASA Admits?
It’s often assumed that NASA’s spacecraft are built to withstand anything space throws at them, but Juno’s mission is particularly risky.
Jupiter’s intense radiation and magnetic fields are far stronger than even NASA anticipated.
In fact, during Juno’s first close pass in August 2016, instruments recorded radiation levels 10 times stronger than expected—so extreme that scientists worried about the long-term survival of the spacecraft.
The assumption has always been that Juno’s protective titanium vault would shield its delicate electronics, but what if Jupiter’s extreme conditions are taking a bigger toll than NASA initially calculated?
A mission failure due to radiation exposure would be a serious blow—not just for Juno, but for future deep-space missions to high-radiation environments.
For now, NASA is publicly downplaying the risk, but the sudden shutdown raises questions about whether Juno will survive its full mission.
How NASA Handles Safe Mode Events
When a spacecraft enters safe mode, it means all non-essential systems, including scientific instruments and cameras, are turned off.
Juno then orients itself toward the Sun to ensure it continues receiving power, while awaiting further instructions from NASA’s engineers.
This isn’t the first time a NASA probe has suddenly gone dark.
Earlier in 2016, the Curiosity rover on Mars also entered safe mode after a system glitch—but successfully recovered within a few days.
Fortunately, Juno has already rebooted and appears to be back online.
However, NASA won’t attempt to fully restore scientific operations until they’ve diagnosed what caused the shutdown in the first place.
Engine Trouble Delays Key Maneuver
Adding to the mission’s challenges, NASA had already decided to postpone a critical maneuver just days before the safe mode event.
Originally, during this flyby, Juno was supposed to fire its main engine to shift from a 53-day orbit into a 14-day science orbit—a move that would allow for more frequent data collection.
But on October 14, NASA engineers discovered that two helium valves in Juno’s engine weren’t behaving as expected, forcing them to delay the maneuver indefinitely.
“We need to conduct further investigations before we move forward with the period reduction maneuver,” said Nybakken.
This means Juno will remain in its current long orbit, limiting the frequency of future close encounters with Jupiter.
While this doesn’t spell doom for the mission, it does mean that NASA must adjust its original timeline, delaying some of the most detailed observations of Jupiter.
What This Means for Juno’s Mission
The good news? Juno’s onboard computer is back online, and NASA is working to recover full functionality.
The next scheduled close flyby is on December 11, and engineers are hopeful that Juno will be fully operational by then.
The bad news? This latest flyby was a missed opportunity—one of only a handful of chances Juno has to collect high-resolution data from Jupiter’s atmosphere.
During its first close approach in August, Juno’s instruments revealed that:
- Jupiter’s famous orange-and-white cloud bands extend deep into the planet’s interior.
- The gas giant’s magnetic field is shockingly irregular, suggesting that its core may be larger and stranger than previously thought.
- The auroras at Jupiter’s poles are unlike any in the solar system, behaving in ways that defy current models.
Scott Bolton likened the mission’s findings to peeling back the layers of an onion:
“We are seeing that those beautiful belts and bands of orange and white we see at Jupiter’s cloud tops extend in some version as far down as our instruments can see, but seem to change with each layer.”
With another flyby coming in December, there’s still hope that Juno will gather more revolutionary data—if it can avoid further malfunctions.
Is Juno Running Out of Time?
Juno’s mission was always a race against time—Jupiter’s radiation is slowly wearing the spacecraft down, and each flyby increases the risk of future malfunctions.
While NASA remains optimistic, these recent issues are a reminder that space exploration is as unpredictable as it is exciting.
The next few months will be critical for Juno’s future—if NASA can fully recover the spacecraft, it still has a chance to unlock some of Jupiter’s biggest secrets.
But if these shutdowns and engine issues continue? Juno’s time in Jupiter’s orbit may be shorter than we thought.
What’s Your Take?
Do you think NASA will be able to fix Juno’s problems? Or are these setbacks signs that the mission is in trouble? Drop a comment below!
