Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

X-rays illuminate the interior of the Moon

20.02.2012
Deep lunar magma is too heavy to produce active volcanoes

Contrary to Earth, our Moon has no active volcanoes, and the traces of its past volcanic activity date from billions of years ago. This is surprising, because recent Moonquake data suggest that there is plenty of liquid magma deep within the Moon because part of the rocks residing there are thought to be molten.

Scientists have now identified a likely reason for this peaceful surface life: the hot, molten rock in the Moon's deep interior could be so dense that it is simply too heavy to rise to the surface like a bubble in water. For their experiments, the scientists produced microscopic copies of moon rock collected by the Apollo missions and melted them at the extremely high pressures and temperatures found inside the Moon. They then measured their densities with powerful X-rays. The results are published in the Journal Nature Geosciences on 19 February 2012.

The team was led by Mirjam van Kan Parker and Wim van Westrenen from VU University Amsterdam and comprised scientists from the Universities of Paris 6/CNRS, Lyon 1/CNRS, Edinburgh, and the European Synchrotron Radiation Facility (ESRF) in Grenoble.

Five decades after the Apollo missions, the formation and geological history of the Moon still hold many secrets. The astronauts not only returned 380 kg of Moon rocks to Earth but also placed many scientific instruments on the lunar surface. Last year, NASA scientists published a new model for the make-up of the interior of the Moon, using Moonquake data from these Apollo-era seismometers. Renee Weber and her colleagues claim that the deepest parts of the lunar mantle, bordering on the small metallic core, are partially molten, by up to 30 per cent. In the Earth, such bodies of magma tend to move towards the surface leading to volcanic eruptions. If the deep interior of the Moon contains so much magma, why don't we see spectacular volcanic eruptions at its surface?

The driving force for vertical movement of magma is the density difference between the magma and the surrounding solid material, making the liquid magma move slowly upwards like a bubble. The lighter the liquid magma is, the more violent the upward movement will be.

To determine the density of lunar magma, Wim van Westrenen and his colleagues synthesised moon rock in their laboratory in Amsterdam, using the composition derived from Apollo samples as their "recipe". The pressures and temperatures close to the core of the Moon are more than 45,000 bar and about 1500 degrees. It is possible to generate these extreme conditions with small samples, heating them with a high electric current while squashing them in a press. By measuring the attenuation of a powerful synchrotron X-ray beam at the ESRF traversing the sample both solid and molten, the density at high pressure and high temperature could be measured. "We had to use the most brilliant X-ray beam in the world for this experiment because the magma sample is so tiny and confined in a massive, highly absorbing container. Without a bright beam of X-rays, you cannot measure these density variations", says Mohamed Mezouar from the ESRF.

The measurements at the ESRF were combined with computer simulations to calculate the magma density at any location in the Moon.

Nearly all the lunar magmas were found to be less dense than their solid surroundings, similar to the situation on Earth. There is one important exception: small droplets of titanium-rich glass first found in Apollo 14 mission samples produce liquid magma as dense as the rocks found in the deepest parts of the lunar mantle today. This magma would not move towards the surface.

Such titanium-rich magma can only be formed by melting titanium rich solid rocks. Previous experiments have shown that such rocks were formed soon after the formation of the Moon at shallow levels, close to the surface. How did they get deep into the mantle? The scientists conclude that large vertical movements must have occurred early in the history of the Moon, during which titanium-rich rocks descended from near the surface all the way to the core-mantle boundary. "After descending, magma formed from these near-surface rocks, very rich in titanium, and accumulated at the bottom of the mantle – a bit like an upside-down volcano. Today, the Moon is still cooling down, as are the melts in its interior. In the distant future, the cooler and therefore solidifying melt will change in composition, likely making it less dense than its surroundings. This lighter magma could make its way again up to the surface forming an active volcano on the Moon – what a sight that would be! – but for the time being, this is just a hypothesis to stimulate more experiments", concludes Wim van Westrenen.

Claus Habfast | EurekAlert!
Further information:
http://www.esrf.fr

More articles from Earth Sciences:

nachricht NASA eyes Pineapple Express soaking California
24.02.2017 | NASA/Goddard Space Flight Center

nachricht 'Quartz' crystals at the Earth's core power its magnetic field
23.02.2017 | Tokyo Institute of Technology

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>