There's water, water everywhere on the dwarf planet Ceres, according to new research. New observations have provided direct evidence that water ice is ubiquitous on the surface and shallow subsurface of this massive asteroid.

Ceres is the largest object in the asteroid belt that lies between Mars and Jupiter, and has long been suspected of containing significant amounts of water — estimates projected up to 30 percent of its total mass. Evidence has pointed to water ice being mixed with the rock on Ceres' surface, and in a few rare cases, more concentrated patches of exposed ice have been found. Ceres has even belched up plumes of water vapor.

The new results come from a global map of Ceres showing the distribution of hydrogen, which can then be used to infer the presence of water. The data supports the theory that Ceres' water content separated from the rock content, and formed an ice-rich crust on the dwarf planet. The fact that so much water is still present on Ceres "confirms predictions that water ice can lie for billions of years within a meter of the surface," the authors write in the new paper detailing the findings. [Amazing Photos of Dwarf Planet Ceres]

Hydrogen on Ceres

NASA’s Dawn spacecraft determined the hydrogen content of the upper yard, or meter, of Ceres’ surface. Blue indicates where hydrogen content is higher, near the poles, while red indicates lower content at lower latitudes.

(NASA / JPL-Caltech / UCLA / MPS / DLR / IDA / PSI Photo)

The global map was created using an instrument on NASA's Dawn probe, which is currently orbiting the dwarf planet, called the Gamma Ray and Neutron Detector (GRaND). This instrument detects two kinds of particles: neutrons, one of the particles that make up atoms, and gamma rays, very high-energy light. When cosmic rays (very high-energy particles from space) crash into the surface of the dwarf planet, the collision can create a spray of debris particles, including neutrons and gamma rays. But the debris isn't random; the characteristics of some of those gamma rays and neutrons can provide information about the chemical composition of the surface of Ceres and to certain depths below the surface. So scientists looking at data from GRaND can learn about the abundance of elements, including potassium, iron and hydrogen on the surface of Ceres, and to a depth of about 3 feet (1 meter).

The instrument cannot directly detect water molecules, but that can be inferred from the data, according to the authors. One way this is done is with computer models, which can recreate the evolution of Ceres, producing various possible outcomes that show how those elements (and water) would be distributed today.

Comparing the models with the new map shows that water ice on Ceres is concentrated near the poles: At high latitudes (past about 40 degrees in both hemispheres), water ice on the surface of Ceres and in the layers just under the surface may compose up to 27 percent of Ceres' mass, according to the new research. Near the equator, the water ice concentration is much lower.

They researchers also compared the map of Ceres with a map of Vesta, another body in the asteroid belt. The data from those global maps show that Ceres has over 100 times more hydrogen than Vesta, and that the hydrogen is distributed more evenly over the surface. That indicates some kind of global process, which implies that water was (and still is) a large component of Ceres' composition, according to the lead author of the new research, Thomas Prettyman, principal investigator for GRaND. Prettyman spoke at a news conference today (Dec. 15) at the annual meeting of the American Geophysical Union in San Francisco.

Prettyman also noted that Ceres' composition has been compared with a family of meteorites called carbonaceous chondrites. These rocks, like most asteroids in the asteroid belt, have evolved very little since the early days of the solar system. But the new map (which also shows the distribution of iron and potassium on Ceres) shows some key differences between Ceres and these meteorites.

"If you look at the elemental composition of Ceres, it bears some resemblance to the carbonaceous contrite meteorites," Prettyman said. "But there are differences that support the idea that ice and rock that came together and formed Ceres actually separated in the interior and were redistributed by processes like convection."

It is possible that Ceres harbors a liquid ocean deep below its surface, but if that is the case, the ocean is likely composed of a very salty chemical mixture, with little or no water, according to Carol Raymond, deputy principal investigator of the Dawn mission, who also spoke at the news conference. Instead, the new results indicate Ceres' water is largely stored in ice deposits near the surface.

A separate study appearing in the journal Nature and also released today revealed the presence of a concentrated patch of surface ice on Ceres, located in a regions cloaked in permanent shadow. But this and other patches of surface ice deposits are "rare," according to the paper's authors, and don't add up to anywhere near the total amount of ice now thought to lie buried just under Ceres' surface.

The Dawn probe entered into orbit around Ceres in March 2015. The spacecraft completed its primary mission in June, and continues to study Ceres as part of its extended mission.

Follow Calla Cofield @callacofield.Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.

**Heavy rocks like these seem to slide across the surface of Racetrack Playa in Death Valley National Park.**
**Credit: Anatoliy Lukich | Shutterstock.com**

California's remote, beautiful, and foreboding Death Valley has held a mystery for almost a century: it has stones that seem to move on their own, when no one is looking. It happens at Racetrack Playa, a dry lakebed known for its "sailing stones." This effect occurs at a few other places as well, though Death Valley is the most famous spot. Thanks to some high-tech sleuthing, the mystery may have been solved, at least partly.

In their book "Mysteries of the World: Unexplained Wonders and Mysterious Phenomena," Herbert Genzmer and Ulrich Hellenbrand state that "the perfectly flat, dry ground is scoured and scraped with paths that suggest these boulders are being moved along the ground... there is no indication of how this movement could have been brought about by outside forces, and no stone has ever been observed actually making its way across the ground."

Not all of the stones in Death Valley move. Those that do only move every two to three years, and they don't all move at the same time or in the same direction. In fact, some seem to have made abrupt 90-degree turns, judging from the tracks, which range from tens of feet to hundreds of feet long. Most of the stones are not huge boulders but instead range from about 6 to 18 inches (15 to 45 centimeters) in diameter.

Several theories have been proposed to explain this curious phenomenon, including some sort of localized, unknown magnetic effect. This theory has been discounted for a variety of reasons including that many of the stones do not contain significant amounts of magnetic elements such as iron, and that the stones should gradually assemble in one place — which they don't. Some have suggested that the strong winds that blow through the area might move the rocks after the lakebed has become slick.

The most likely solution to the mystery involves a combination of wind, temperature and water. Although Racetrack Playa is a dry lakebed, it is not always dry; in fact, water collects on the surface after rainfall or when snow from surrounding peaks melts. Brian Dunning, a California researcher who discussed this mystery on his Skeptoid podcast, notes that when water is present and the temperature falls below freezing — as it sometimes does — a thin sheet of ice is created: "Solid ice, moving with the surface of the lake and with the inertia of a whole surrounding ice sheet, would have no trouble pushing a rock along the slick muddy floor... As the wind shifts and the flow ebbs, these ice floes drag the rocks across the slippery mud surface in zig-zagging paths, even moving heavy rocks and sometimes dragging some but washing past others nearby."

NASA researcher Ralph Lorenz became intrigued by the enigmatic stones while studying Death Valley weather conditions. He developed a tabletop experiment to show how the rocks might glide across the surface of the lakebed.

"I took a small rock and put it in a piece of Tupperware, and filled it with water so there was an inch of water with a bit of the rock sticking out," Lorenz told Smithsonian.com.

After putting the container in the freezer, Lorenz ended up with a small slab of ice with a rock embedded in it. By placing the ice-bound rock in a large tray of water with sand at the bottom, all he had to do was gently blow on the rock to get it to move across the water. And as the ice-embedded rock moved, it scraped a trail in the sand at the tray's bottom.

Shy stones

Though such explanations are plausible, they were very difficult to prove since no one had actually seen or recorded the stones' movements. Understandably, no one has volunteered to spend every minute of their lives — day and night for several years — enduring temperatures that can reach well above 100 degrees F (37 C), hoping to see a stone move. Furthermore, Racetrack Playa is almost three miles long and over a mile wide (4.8 by 1.6 kilometers). A person of course can't be everywhere at once, and would have to pick one or two rocks to closely and continually monitor just in case they happen to suddenly move. And can you imagine the frustration if someone spent two years watching a non-moving rock, only to later learn that several other rocks on another part of the lakebed had moved while they weren't watching?

Fortunately, the technology exists to investigate the mystery remotely. In 2013, a team of scientists using rocks with motion-activated GPS units and time-lapse photography captured the first video footage of the stones creeping across the desert floor. [Related: High-Tech Sleuthing Cracks Mystery of Death Valley's Moving Rocks]

It turns out that jagged plates of thin ice, resembling panels of broken glass, bulldoze the rocks across the flooded playa. Driven by gentle winds, the rocks seem to hydroplane atop the fluffy, wet mud. The scientists revealed their findings in the Aug. 27 issue of the journal PLOS One.

The mystery has not been solved completely, however. The video shows how smaller rocks move, but no one has ever seen the gigantic playa boulders budge an inch. Another process may be at work on the biggest rocks, according to Jim Norris, an engineer and member of the team.

"I know there are people who like the mystery of it and will probably be somewhat disappointed that we've solved it," Norris said. "It's a fascinating process, and in many ways I hope that there's more to be discovered. Never say never."