Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mercury's surface dominated by volcanic activity

07.07.2008
Volcanism has played a more extensive role in shaping the surface of Mercury than scientists had thought. This result comes from multispectral imaging data gathered in January 2008 by MESSENGER, the latest spacecraft to visit the sun's innermost planet.

MESSENGER data has also identified and mapped surface rock units that correspond to lava flows, volcanos, and other geological features. At the same time, the spacecraft's suite of instruments has confirmed an apparent planet-wide iron deficiency in Mercury's surface rocks.

MESSENGER (short for MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is the first spacecraft to visit Mercury since NASA's Mariner 10 made three flyby passes in 1974 and 1975. MESSENGER, which is operated for NASA by the Applied Physics Laboratory of Johns Hopkins University in Baltimore, will make two more Mercury flybys (Oct. 6, 2008 and Sept. 29, 2009) before going into orbit around the planet, March 18, 2011.

Mercury and MESSENGER form the subject of 11 papers in a special section devoted to the January flyby in the July 4, 2008, issue of the scientific journal Science.

Mark S. Robinson of Arizona State University is the lead author for a paper in the issue which spotlights data on composition variations in Mercury's surface rocks using their multispectral colors. Robinson, a professor of geology in ASU's School of Earth and Space Exploration, part of the College of Liberal Arts and Sciences, is a co-investigator on the MESSENGER geology science team. Besides Robinson, the multispectral paper has 12 additional co-authors from other institutions.

"We have now imaged half of the part of Mercury that was never seen by Mariner 10," says Robinson. "The picture is still incomplete, but we'll get the other half on October 6." Back in 1974-1975, the orbital trajectory that let Mariner to make three passes at Mercury limited it to photographing less than half the planet's surface. This left the rest of Mercury unknown until MESSENGER's arrival in January let scientists begin to fill in the gaps.

Lava plains

MESSENGER's big-picture finding, says Robinson, is the widespread role played by volcanism. While impact craters are common, and at first glance Mercury still resembles the moon, much of the planet has been resurfaced through volcanic activity.

"For example, according to our color data the Caloris impact basin is completely filled with smooth plains material that appears volcanic in origin," Robinson explains. "In shape and form these deposits are very similar to the mare basalt flows on the moon. But unlike the moon, Mercury's smooth plains are low in iron, and thus represent a relatively unusual rock type."

The Caloris plains, he adds, cover at least a million square kilometers (390,000 square miles), or big enough to engulf Arizona, Nevada, and California put together. The plains' size implies the existence of large sources of magma in Mercury's upper mantle.

Multispectral imaging also shows that besides lava flows, Caloris has "red spots," which also appear volcanic. "Red spots have diffuse boundaries and sometimes lie centered on rimless depressions," Robinson says. "Right now they look to be caused by explosive, pyroclastic eruptions."

In addition, Robinson notes, three major rock units stand out in MESSENGER's multispectral imaging.

"We mapped the new hemisphere using moderate resolution images of 5 kilometers [3 miles] per pixel," he says. "As on the Mariner hemisphere, we saw three major units defined by their colors. These units are relatively high-reflectance smooth plains, average cratered terrain, and low-reflectance material."

Where's the iron?

The low-reflectance material is particularly enigmatic, says Robinson. "It's an important and widespread rock that occurs deep in the crust as well as at the surface, yet it has very little ferrous iron in its silicate minerals."

That, he says, makes it unusual. "You expect to find low-reflectance volcanic rocks having a high abundance of iron-bearing silicate minerals, but that's not the case here." One possible solution, he says, is that iron is actually present but invisible to MESSENGER's spectrometers because it's hidden within the chemical structure of minerals such as ilmenite.

Solving the paradox should help scientists unravel Mercury's history. "If you want to understand how a planet has evolved," Robinson explains, "you need to know about the minerals in its crust and mantle. Unfortunately, we are not going to be able to drill into Mercury for a long time to come. All we can do is study its volcanic rocks in detail. They give a glimpse into the planet's mantle."

"Right now," says Robinson, "it looks as if Mercury formed with a deficiency in ferrous iron. But we'll know more about its bulk composition, and thus its history, once MESSENGER gets into orbit in 2011. That's when the surface rocks can be studied much more closely, using the full set of instruments."

Besides Robinson, the other authors are Scott L. Murchie, David T. Blewett Deborah L. Domingue, S. Edward Hawkins III, Ralph L. McNutt Jr., Louise M. Prockter (Johns Hopkins University Applied Physics Laboratory), James W. Head (Brown University), Gregory M. Holsclaw, William E. McClintock (Laboratory for Atmospheric and Space Physics, University of Colorado), Sean C. Solomon (Carnegie Institution of Washington), Timothy J. McCoy (National Museum of Natural History, Smithsonian Institution), Thomas R. Watters (National Air and Space Museum, Smithsonian Institution).

Robert Burnham, robert.burnham@asu.edu
480-458-8207
School of Earth and Space Exploration

Robert Burnham | EurekAlert!
Further information:
http://www.asu.edu

More articles from Earth Sciences:

nachricht Six-decade-old space mystery solved with shoebox-sized satellite called a CubeSat
15.12.2017 | National Science Foundation

nachricht NSF-funded researchers find that ice sheet is dynamic and has repeatedly grown and shrunk
15.12.2017 | National Science Foundation

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>