Pristine cometary dust under the microscope
An international team of researchers with Pascale Ehrenfreund from Leiden University has discovered that the dust particles of comet 67P/Churyumov–Gerasimenko are made up of even smaller particles. This discovery confirms that clumps of dust form the basis for comets and planets.
First atomic force microscope in space
The researchers published their finding on 31 August in the scientific journal Nature. They were able to carry out their research using the first atomic force microscope in space, located on board the Rosetta unmanned spacecraft. The pristine condition of the dust particles means that scientists can learn more about how our solar system was created. Comets can help here; they are a kind of time capsule containing matter in an almost untouched state.
This is the first time that pristine dust particles from a comet have been seen in such detail. During an earlier expedition to the Wild 2 comet, the particles entered the measuring instrument so fast that they could have been damaged. And research on space dust in the atmosphere is hampered by the fact that the dust can be damaged by long-term solar radiation and collisions with other particles.
Dust is made up of clumps
The instrument that the researchers used this time is MIDAS: Micro-Imaging Dust Analysis System. It shows the size, shape and structure of the planetary dust. The dust is apparently made up of clumps of smaller particles that differ in size from tens of micrometers to several hundred namometers. They also vary in shape, from loose grains to larger aggregates that are elongated and porous. The researchers also saw one clump made up of 114 smaller dust particles.
Researchers had previously seen the larger lumps of matter of 67P using a different instrument. These in their turn seemed to be made up of smaller lumps. These smaller dust particles have now also been examined. The observations confirm the theories for the origin of comets and planets that state that small dust particles merge, forming larger clumps and eventually planets and comets.