Scientists have been working for centuries to understand the composition of Jupiter. It's no wonder: this mysterious planet is by far the largest in our solar system and chemically closest to the sun. Understanding Jupiter is a key to learning more about how our solar system has formed and even how other solar systems are evolving.
But astronomers have been asking a critical question for generations: is there water deep in Jupiter's atmosphere, and if so, how much?
Gordon L. Bjoraker, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, reported in a recent article in the Astronomical Journal that he and his team brought the Jovian research community closer to the answer
Looking from ground-based telescopes to wavelengths sensitive to deep heat radiation from Jupiter's stubborn storm, the Great Red Spot, they discovered the chemical signatures of water over the planet's deepest clouds. The pressure of the water, the researchers conclude, combined with their measurements of another oxygen-containing gas, carbon monoxide, imply that Jupiter has 2 to 9 times more oxygen than the Sun. This finding supports theoretical and computer simulation models that have predicted abundant water (H 2 O) on Jupiter from oxygen (O) with molecular hydrogen (H 2 ). [[1
"It turns out that they are not so fat that they block our ability to see deeply," said Bjoraker, "which was a pleasant surprise."
New spectroscopic technology and pure curiosity gave the team a boost to look deep into Jupiter, which has an atmosphere of thousands of miles in depth, Bjoraker said, "We thought, well, let's just see what's out there.
The data collected by Bjoraker and his team will supplement the information gathered by NASA's Juno spacecraft as it orbits the planet once every 53 days from north to south.
Juno is looking for, among other things to water with its own infrared spectrometer and a microwave radiometer that has seen deeper than anyone else – up to 100 bar or 100 times the atmospheric pressure on the earth's surface. (Altitude on Jupiter is measured in bars that represent the atmospheric pressure because the planet has no surface like the Earth from which you can measure altitude.)
When Juno returns similar water findings, he supports Bjoraker's ground-based technique "It could open a new window to solve the water problem," Goddards said Amy Simon, Planetary Atmospheric Expert.
"If it works, we may be able to apply it elsewhere, like Saturn, Uranus, or Neptune, where we do not are. "
Juno is the newest spacecraft tasked with finding probable gaseous waters on this huge gas planet.
Water is a significant and abundant molecule in our solar system. It has produced life on Earth and now lubricates many of its major processes, including the weather. This is also a critical factor in Jupiter's turbulent weather and in determining whether the planet has a core of rock and ice.
Jupiter is considered the first planet to have formed by merging the elements of the formation of The Sun as our star from an amorphous nebula into the fiery gas ball we see today. A widely accepted theory until a few decades ago was that Jupiter was identical in composition to the Sun; a ball of hydrogen with a touch of helium – all gas, no core.
But there are signs that Jupiter has a core, perhaps ten times the mass of Earth. Spacecraft that previously visited the planet found chemical evidence that it formed a core of rock and water ice before it mixed with gases from the sun's nebula to create its atmosphere. The way Jupiter's gravity pulls at Juno also supports this theory. There is even lightning and thunder on the planet, phenomena driven by moisture.
"The moons orbiting Jupiter are mostly water-ice, so the whole area has a lot of water," Bjoraker said. "Why should the planet – which is this huge gravitation good, where everything falls into it – also be rich in water?"
The water question has driven planetary scientists mad; Practically every time there are traces of H2O, something happens to free them from the smell. A popular example among Jupiter experts is NASA's Galileo spacecraft, which in 1995 dropped a probe into the atmosphere, which was located in an unusually dry region. "It's like sending a probe to Earth, landing in the Mojave Desert, and concluding that the earth is dry," Bjoraker explained.
In search of water, Bjoraker and his team used radiation data from the Maunakea summit in Hawaii in 2017. They rely on the world's most sensitive infrared telescope at the World Cup Keck Observatory, and also on a new instrument, the one wider range of gases at the NASA's infrared telescope.
The idea was to analyze the light energy emitted by Jupiter's clouds to identify the heights of their cloud layers. This would help scientists determine the temperature and other conditions that affect the types of gases that can survive in these regions.
Planet atmosphere experts expect Jupiter to have three cloud layers: a lower layer of water ice and liquid water, a middle layer of ammonia and sulfur, and an upper layer of ammonia.
To confirm this by observations on the ground, Bjoraker's team studied infrared wavelengths in which most gases do not absorb heat absorbing chemical signatures. In particular, they analyzed the absorption patterns of a form of methane gas. Since Jupiter is too warm to freeze methane, its abundance should not change from one place to another on the planet.
"If you see that the strength of the methane lines varies from the inside to the outside of the Great Red Spot, that's not because there's more methane there than there," Bjoraker said, "because thicker, deeper clouds are the radiation in the Great Red Block Spot. "
Bjoraker's team found evidence of the three cloud strata in the Great Red Spot, supporting earlier models. The deepest cloud cover is at 5 bar, the team said, right where the temperature reaches freezing point for water, Bjoraker said, "so I say we've probably found a cloud of water." The position of the cloud of water plus the amount of carbon monoxide that the researchers identified on Jupiter confirms that Jupiter is rich in oxygen and therefore water.
Bjoraker's technology now needs to be tested on other parts of Jupiter to get a complete picture of global water wealth, and his data came in line with Juno's findings.
"Jupiter's abundance of water will tell us a lot about how the huge planet formed, but only if we can find out how much water there is in the whole planet," said Steven M. Levin, a Juno project scientist at Jet NASA's Propulsion Laboratory in Pasadena, California.
Image: Jupiter's southern hemisphere
G. L. Bjoraker et al., The Gas Composition and Deep Cloud Structure of the Great Red Spot of Jupiter, The Astronomical Journal (2018). DOI: 10.3847 / 1538-3881 / aad186