NASA's recent research confirms that Saturn is losing its iconic rings at the maximum rate estimated from the Voyager 1 & 2 observations decades ago. The rings are pulled by gravity as dusty rain from ice particles under the influence of Saturn's magnetic field in the Saturn.
"We estimate that this" ring rain "will drain a lot of water products that could fill an Olympic swimming pool in half an hour from the Saturn rings," said James O'Donnoghue of NASA's Goddard Space Flight Center in Greenbelt , Maryland. "For that reason alone, the entire ring system will have disappeared in 300 million years. In addition, the measured ring material of the Cassini spacecraft has fallen into the equator of Saturn and the rings will have to live for less than 1
Scientists have long wondered whether Saturn formed with the rings or whether the planet acquired them later in life. The new study argues for the latter scenario, as it is unlikely that they are older than 100 million years, since the C-ring would take so long to become what it is today, provided it was once so as tight as the B-ring. "We're lucky to see Saturn's ring system appearing to be in the middle of its life, but if the rings are transient we may just have thin spikes on the giant system of Jupiter, Uranus and Neptune today!" # 39; Donoghue added.
Various theories have been suggested for the origin of the ring. If the planet got them later in life, the rings could have formed when small, icy moons collided in orbit around Saturn, perhaps because their orbits were disturbed by a gravity hauler by a passing asteroid or comet.
The first signs of ringing rain came from Voyager's observations of seemingly unrelated phenomena: strange fluctuations in Saturn's electrically charged upper atmosphere (ionosphere), density fluctuations in Saturn's rings, and a Trio of narrow, dark bands that circle the planet in the northern mid latitudes. These dark bands appeared in images of Saturn's hazy upper atmosphere (stratosphere) created in 1981 by NASA's Voyager 2 mission.
In 1986, NASA Goddard's Jack Connerney published in Geophysical Research Letters an article linking these tight dark bands to the shape of Saturn's enormous magnetic field, suggesting that electrically charged ice particles from Saturn's rings flow down invisible magnetic field lines and Drain water into the upper atmosphere of Saturn, where these lines emerge from the planet. The inflow of water from the rings, which appeared at certain latitudes, removed the stratospheric haze and made it appear dark in the reflected light, creating the narrow dark bands captured in the Voyager images.
Saturn's rings are mostly chunks of water ice the size of microscopic dust grains to boulders with a diameter of several meters. Ring particles are caught in a balancing act between the gravitational pull of Saturn's gravity, which she wants to pull back into the planet, and her orbital velocity, which she wants to hurl outward into outer space. Tiny particles can be electrically charged by ultraviolet light from the sun or by plasma clouds generated by micrometeoroid bombardment on the rings. When this happens, the particles can sense the attraction of the Saturn magnetic field, which curves inward toward the planet at the Saturn rings. In some parts of the rings, the balance of forces on these tiny particles changes dramatically after charging, and the gravity of Saturn pulls them along the magnetic field lines into the upper atmosphere.
As soon as ice particles evaporate there, the icy ring particles evaporate. Water can react chemically with the ionosphere of Saturn. One result of these reactions is the increase in the lifetime of electrically charged particles, the so-called H3 + ions, which consist of three protons and two electrons. When excited by sunlight, the H3 + ions glow in infrared light, as witnessed by O & # 39; Donoghue's team using special instruments at the Keck Telescope in Mauna Kea, Hawaii.
Their observations showed glowing bands in the northern and southern hemispheres of Saturn. The magnetic field lines intersecting the ring plane enter the planet. They analyzed the light to determine the rainfall of the ring and its effects on the ionosphere of Saturn. They found that the amount of rain was remarkably well in line with the astonishing highs ascertained more than three decades earlier by Connerney and his colleagues, with a region in the south receiving most of it.
The team also discovered a glowing band in a higher zone latitude in the southern hemisphere. Here, the magnetic field of Saturn crosses the orbit of Enceladus, a geologically active moon that shoots geysers of water ice into space, suggesting that some of these particles also rain on Saturn. "That was not a complete surprise," Connerney said. "We also identified Enceladus and the E-ring as a plentiful source of water based on another narrow dark band in this old Voyager image." The geysers, first observed in 2005 by Cassini instruments, are believed to come from an ocean of liquid water under the frozen surface of the tiny moon. Its geological activity and its ocean of water make Enceladus one of the most promising places to look for extraterrestrial life.
The team would like to see how the ring rain changes with the seasons on Saturn. As the planet progresses in its 29.4-year orbit, the rings are exposed to the sun to varying degrees. Since ultraviolet light from the sun charges the grains of ice and it responds to the magnetic field of Saturn, the amount of ring rain should be changed by different solar irradiation.