Glass bubble find may explain weird lunar soil

Posted by Emma Woollacott

The discovery of nanoparticles inside bubbles of glass in lunar soil could explain why the moon's surface topsoil has such unusual properties.

It actually floats above the lunar surface, is very chemically active, and is both sticky and highly abrasive.

The explanation, says Queensland University of Technology's soil scientist Marek Zbik, lies in the nano and submicron particles found in the soil, which he's examined using synchrotron-based nano tomography.

"We were really surprised at what we found. Instead of gas or vapour inside the bubbles, which we would expect to find in such bubbles on Earth, the lunar glass bubbles were filled with a highly porous network of alien-looking glassy particles that span the bubbles' interior," he says.

"It appears that the nanoparticles are formed inside bubbles of molten rocks when meteorites hit the lunar surface. Then they are released when the glass bubbles are pulverised by the consequent bombardment of meteorites on the moon's surface."

The result, he says, is a type of soil which is entirely unknown on Earth.

Because nanoparticles behave according to the laws of quantum physics, materials containing them behave rather strangely.

"We don't understand a lot about quantum physics yet but it could be that these nano particles, when liberated from their glass bubble, mix with the other soil constituents and give lunar soil its unusual properties," he says.

"Lunar soil is electro-statically charged so it hovers above the surface; it is extremely chemically active; and it has low thermal conductivity eg it can be 160 degrees above the surface but -40 degrees two metres below the surface. It is also very sticky and brittle such that its particles wear the surface off metal and glass."

The reason similar nanoparticles aren't found on Earth is probably because its atmosphere cushions the impact of meteorites.

"When they hit the moon there is a very violent reaction. Huge temperatures are generated which melts the rock. The pressure goes and a vacuum is created. Bubbles occur in the molten glass rock like soft drink bubbles trying to escape the bottle," says Zbick.

"Our work now is to understand how those particles evolve from this process. It may also lead us to completely different way of manufacturing nanomaterials."