Uranus may have experienced a rare event during Voyager 2’s only flyby

by Junna Base November 12, 2024

“The spacecraft saw Uranus under conditions that only occur about 4% of the time,” said the lead author of a new study.

Much of our understanding of Uranus comes from the Voyager 2 flyby, which remains the only spacecraft visit to the planet to date.
Voyager 2’s data on the magnetosphere surrounding Uranus has puzzled scientists for decades.
As a result, Uranus gained a reputation as an outlier in our solar system for decades. But new research could turn that understanding on its head.

A lone space probe’s visit to Uranus may have left us with a completely false impression of the ice giant for almost 40 years.

The strange, sideways-spinning planet – the third largest in our solar system – has always been a mystery to astronomers. But when Voyager 2 examined Uranus up close in 1986, scientists were able to uncover some insights that, while confusing, at least shed some light on a crucial feature that seemed to distinguish the planet from other giants like Jupiter.

At least that’s what they thought.

A new look at data collected during Voyager 2’s flyby revealed that the probe’s visit to Uranus may have coincided with a rare interstellar event. The findings, published Monday in a study in the journal Nature Astronomy, suggest that our understanding of the planet’s protective magnetic field, or magnetosphere, may be flawed.

“If Voyager 2 had arrived just a few days earlier, it would have observed a completely different magnetosphere at Uranus,” lead study author Jamie Jasinski, a physicist at NASA’s Jet Propulsion Laboratory in Pasadena, California, said in a statement. “The spacecraft saw Uranus under conditions that only occur about 4% of the time.”

Voyager 2 visited Uranus in 1986

Much of our understanding of Uranus comes from the Voyager 2 flyby, which remains the only spacecraft visit to the planet to date.

The probe was launched from Cape Canaveral, Florida, along with its twin Voyager 1 in 1977 to explore the most remote areas of our solar system. The probes, which continue to travel billions of kilometers away, have both reached interstellar space – Voyager 1 in 2012 and Voyager 2 in 2018, NASA said.

But long before that, Voyager 2 stopped at Uranus and came within 50,600 miles of Uranus’ cloud surfaces. Encountering the planet on January 24, 1986, the probe provided detailed photos and other data about the world, its moons, its magnetic field and its dark rings.

Why were scientists interested in Uranus’ magnetosphere?

Voyager 2’s data on the magnetosphere surrounding Uranus has puzzled scientists for decades.

Magnetospheres form a protective bubble around planets with magnetic cores and magnetic fields, protecting them from the Sun’s harmful stream of gas (or plasma) emitted in the solar winds. Scientists have long been interested in learning more about the magnetospheres of other planets in hopes of better understanding Earth’s magnetospheres.

What made Uranus’ magnetosphere so strange was its radiation belts with an unexpected intensity that rivaled that of Jupiter.

Equally puzzling was the absence of plasma. The energetic ionized particles are common in the magnetospheres of other planets, and scientists had theorized that the five large uranium moons in the magnetic bubble should have produced them.

Instead, Voyager 2’s results forced them to conclude that the moons must be inactive.

Solar wind may have distorted Voyager data: study

As a result, Uranus gained a reputation as an outlier in our solar system for decades.

Now new research could turn this understanding on its head.

Although it was far from intentional, Voyager 2’s flyby may have occurred at the same time that unusual space weather suppressed the planet’s magnetic field – distorting the probe’s data. Solar winds impacting the magnetosphere would have temporarily driven plasma out of the system while increasing the magnetosphere’s power, according to the study.

So instead of getting a complete picture of Uranus, scientists on Earth were presented with a misleading “snapshot in time,” Linda Spilker, project scientist for the two Voyager probes at JPL, said in a statement.

This means that these five large moons of Uranus may be active after all.

“This new work explains some of the apparent contradictions and will once again change our view of Uranus,” said Spilker, who served as one of the mission scientists for Voyager 2 during his visit.

Will NASA now visit Uranus again?

The study’s authors say their research underscores how little we know about Uranus and how important future missions to the planet could be.

A 2022 report from the National Academies of Sciences, Engineering and Medicine called on NASA to make another mission to Uranus a priority in the next decade – something the space agency appears to have in the works.

A 2023 Scientific American report highlights plans for NASA to launch a spacecraft by 2032 that will orbit the planet and send a probe into its atmosphere.

Eric Lagatta covers breaking and breaking news for USA TODAY. Reach him at [email protected]

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