A gas bubble 22,000 times the size of the Earth exploded on Uranus

This happened back in 1986, but could happen again.

The famous portrait of Uranus made by the Voyager -2 spacecraft.

On a constantly growing map of researchers of the solar system there is a giant white spot. Over the past two decades, a real fleet of probes has measured earthquakes on Mars , studied the recesses in the rings of Saturn , observed the jet flows on Jupiter and heard the heartbeat of Pluto . But from the point of view of careful and personal study, the image of Uranus did not significantly go beyond the faceless blue beach ball captured by the old Voyager -2 spacecraft in 1986.

But last year, while browsing through the NASA archives, two planetary scientists noticed something that earlier analyzes had overlooked — a flash in the magnetic field of Uranus when a spacecraft flew through a kind of magnetic bubble. A new result , published last summer in the Geophysical Research Letters, appeared when planetarium scientists began to shift their attention to some of the deepest mysteries of the field.

“Cassini’s mission [to Saturn] is over and people start saying,“ OK, what else can we do? ”Says Heidi Hammel , planetary astronomer and vice president of science at the Association of Universities for Astronomy Research.

Gina DiBraccio and Daniel Gershmanfrom NASA, Goddard Space Flight Center are two such researchers. Encouraged by the growing interest of the community in the most distant planets, they spent hours manually re-processing data thirty years ago. According to DiBraccio, Voyager scientists calculated the strength of the magnetic field as a whole, so short changes in the magnetometer readings were simply considered a nuisance. But, increasing these uneven jumps and downs, DiBraccio and Gershman noticed a special 60-second segment of the 45-hour span of Voyager-2, where the field rose and fell in an instantly recognizable way. "What do you think, it could be ... a plasmoid?" Gershman asked DiBraccio, according to a NASA press release .

Plasmoids are charged atmospheric balls released into space when the solar wind revolves around a planet. The loss of such clumps can radically change the world over a long period of time, and studying them can give an idea of ​​how the planets live and die. Researchers noticed their cleavage from different planets, but Voyager-2, floating through a magnetic gap, provoked the first plasmoid for Uranus. “We expected that Uranus would most likely have plasmoids; however, we didn’t know exactly what they would look like, ”says DiBraccio.

Now that they have caught one plasmoid, she says that it looks very similar to what they saw at Saturn or Jupiter, but it occupies a relatively large mass. (This plasmoid formed a cylinder about 22,000 times larger than the Earth). A large number of such discoveries could remain in the archives, waiting for new analyzes. “Most Voyager-2 data is available on NASA's Planetary Data System,” says DiBraccio, “and there is probably much more to learn.”

In particular, Uranus continues to require further study. In 2014, Erich Karkoszka, an astronomer at the University of Arizona, revised Voyager-2 images with modern processing methods. Combining 1600 images and enhancing contrast, Karkoshka’s work showed that the world of the planet, painted with clouds in the form of candy stripes, hiding all the time in a soft blue ball.

In addition to its invaluable complexity, it is also a strange planet. Where others rotate, Uranus rolls, leaning on its side, the poles of which are directed mainly to or from the sun. Its magnetic field is also obstructed, offset from the center of the planet and tilted at an angle of 60 degrees to the side. Planetary astronomers are blind to this magnetic field from Earth, although the Hubble Space Telescope can sometimes glimpse through the auroras of Uranus, which can shine far from the poles .

The Voyager team initially suggested that the magnetic wobble was due to Uranus lying on his stomach, but when three years later a spacecraft flew past Neptune (which stands straight), he saw the same apparent mismatch between the planet and its field. Researchers are now suggesting that something in the inner workings of the world should highlight their magnetic fields. “Boy, we would like to refine this theory,” says Hammel.

The next generation of planetary scientists can do just that, as interest in sending a special mission to Uranus or Neptune is growing. Rough sketches of possible studies were published in 2018 and at the beginning of last week.. DiBraccio says that more such proposals are now in the making. A common dream is to send a Cassini-style orbiter that will fly around one of the planets, exploring its magnetic field and studying its heat flux. The spacecraft will also carry at least one smaller probe to launch into the atmosphere. There he could measure the invisible gases left over from the formation of the planet.

And if the orbiting satellite is aimed at Neptune, it can plan dates with the mysterious moon Triton (not to be confused with the Titan of Saturn). Probably the former dwarf planet Neptune, torn from an almost inaccessible kingdom ruled by Pluto and other frozen bodies, Triton can hide the underground ocean.

Understanding the outer limits of our solar system has never seemed so relevant.NASA is striving to plan its planetary exploration decade after decade, and they are currently choosing targets for the late 2020s and early 2030s. In addition, between the last so-called “ten-year study” and the current one, the science of exoplanets has advanced significantly, and Neptune and Uranus have become more than just local oddities.

Researchers now know that Sub-Neptune-like worlds are the most common type of planet in the galaxy.. And many of these worlds are probably the planets of the “ice giants,” akin to our great blue duo. Unlike gas giants, which are mainly composed of hydrogen and helium, these planets are mainly composed of heavier molecules such as water and ammonia. If researchers want to understand what makes these worlds so widespread in alien systems and why our solar system is so strange, they will have to find out everything in their power about Uranus and Neptune.

But our space backyard is huge, and access to the fence will take time and careful planning. The sun shines too weak for solar panels, so atomic energy is the only option for a long-term mission. And billions of miles are just a long way off.
“Even with our best rockets and gravitational accelerators, we still have a decade,” says Hammel. Between technology development and mission development, she hopes to see the launch of the probe, even if she can’t work with the data that she will ever send back to Earth. “Most of us tend to think in the long run,” she says.

Evidence of Uranus plasmoids was lost in Voyager-2 data for thirty years before DiBraccio and Gershman came across them. The next meeting with the ice giant may take place no earlier than twenty years later, and any researchers who may someday draw additional information from their previous data are probably not even born. The idea of ​​what kinds of discoveries may be ahead gives astronomers such as Hammel a unique long-term perspective. “I dream of exploring Uranus and Neptune and dream of fantastic space telescopes,” says Hammel, “so we are going through difficult times.” We dream of the future. ”