Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ceres: The tiny world where volcanoes erupt ice

02.09.2016

Ahuna Mons is a volcano that rises 13,000 feet high and spreads 11 miles wide at its base. This would be impressive for a volcano on Earth. But Ahuna Mons stands on Ceres, a dwarf planet less than 600 miles wide that orbits the Sun between Mars and Jupiter. Even stranger, Ahuna Mons isn't built from lava the way terrestrial volcanoes are -- it's built from ice.

"Ahuna is the one true 'mountain' on Ceres," said David Williams, associate research professor in Arizona State University's School of Earth and Space Exploration. "After studying it closely, we interpret it as a dome raised by cryovolcanism."


Volcanic dome Ahuna Mons rises above a foreground impact crater, as seen by NASA's Dawn spacecraft with no vertical exaggeration. Eruptions of salty, muddy water built the mountain by repeated eruptions, flows, and freezing. Streaks from falls of rocks and debris run down its flanks, while overhead views show fracturing across its summit.

Credit: Dawn Science Team and NASA/JPL-Caltech/GSFC

This is a form of low-temperature volcanic activity, where molten ice -- water, usually mixed with salts or ammonia -- replaces the molten silicate rock erupted by terrestrial volcanoes. Giant mountain Ahuna is a volcanic dome built from repeated eruptions of freezing salty water.

Williams is part of a team of scientists working with NASA's Dawn mission who have published papers in the journal Science this week. His specialty is volcanism, and that drew him to the puzzle of Ahuna Mons.

"Ahuna is truly unique, being the only mountain of its kind on Ceres," he said. "It shows nothing to indicate a tectonic formation, so that led us to consider cryovolcanism as a method for its origin."

Dawn scientist Ottaviano Ruesch, of NASA's Goddard Space Flight Center, Greenbelt, Maryland, is the lead author on the Science paper about Ceres volcanism. He says, "This is the only known example of a cryovolcano that potentially formed from a salty mud mix, and which formed in the geologically recent past."

Williams explained that "Ahuna has only a few craters on its surface, which points to an age of just couple hundred million years at most."

According to the Dawn team, the implications of Ahuna Mons being volcanic in origin are enormous. It confirms that although Ceres' surface temperature averages almost -40° (Celsius or Fahrenheit; the scales converge at this temperature), its interior has kept warm enough for liquid water or brines to exist for a relatively long period. And this has allowed volcanic activity at the surface in recent geological time.

Ahuna Mons is not the only place where icy volcanism happens on Ceres. Dawn's instruments have spotted features that point to cryovolcanic activity that resurfaces areas rather than building tall structures. Numerous craters, for example, show floors that appear flatter than impacts by meteorites would leave them, so perhaps they have been flooded from below. In addition, such flat-floored craters often show cracks suggesting that icy "magma" has pushed them upward, then subsided.

A few places on Ceres exhibit a geo-museum of features. "Occator Crater has several bright spots on its floor," said Williams. "The central spot contains what looks like a cryovolcanic dome, rich in sodium carbonates." Other bright spots, he says, occur over fractures that suggest venting of water vapor mixed with bright salts.

"As the vapor has boiled away," he explained, "it leaves the bright 1salts and carbonate minerals behind. "

Looking inside

Although volcanic-related features appear across the surface of Ceres, for scientists perhaps the most interesting aspect is what these features say about the interior of the dwarf world. Dawn observations suggest that Ceres has an outer shell that's not purely ice or rock, but rather a mixture of both.

Recently, Williams was involved in research that discovered that large impact craters are missing, presumably erased by internal heat, but smaller craters are preserved. "This shows that Ceres' crust has a variable composition -- it's weak at large scales but strong at smaller scales," he said. "It has also evolved geologically."

In the big picture, said Williams, "Ceres appears differentiated internally, with a core and a complex crust made of 30 to 40 percent water ice mixed with silicate rock and salts." And perhaps pockets of brine still exist in its interior.

"We need to continue studying the data to better understand the interior structure of Ceres," said Williams.

Ceres is the second port of call for the Dawn mission, which was launched in 2007 and visited another asteroid, Vesta, from 2011 to 2012. The spacecraft arrived at Ceres in March 2015. It carries a suite of cameras, spectrometers, and gamma-ray and neutron detectors. These were built to image, map, and measure the shape and surface materials of Ceres, and they collect information to help scientists understand the history of these small worlds and what they can tell us of the solar system's birth.

NASA plans for Dawn to continue orbiting Ceres and collecting data for another year or so. The dwarf planet is slowly moving toward its closest approach to the Sun, called perihelion, which will come in April 2018. Scientists expect that the growing solar warmth will produce some detectable changes in Ceres' surface or maybe even trigger volcanic activity.

"We hope that by observing Ceres as it approaches perihelion, we might see some active venting. This would be an ideal way to end the mission," said Williams.

Robert Burnham | EurekAlert!

Further reports about: craters dwarf volcanic activity volcanism volcanoes

More articles from Physics and Astronomy:

nachricht A tale of two pulsars' tails: Plumes offer geometry lessons to astronomers
18.01.2017 | Penn State

nachricht Studying fundamental particles in materials
17.01.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

A big nano boost for solar cells

18.01.2017 | Power and Electrical Engineering

Glass's off-kilter harmonies

18.01.2017 | Materials Sciences

Toward a 'smart' patch that automatically delivers insulin when needed

18.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>