were separated by a hand magnet, and the grains obtained from various fractions were subjected to light microscope, XRD, microprobe, and SEM examinations.
This is because the temperature of a comet impact is far higher than that for micrometeorites
- providing an environment for 'shock chemistry', in which oxygen tied up in comet ices is liberated to form carbon monoxide.
They examined a large supply of micrometeorites
from the same Antarctic ice field as ALH84001.
I'm cautiously excited," said Westphal, who added that the researchers must conduct more tests to ensure that their particles are truly interstellar grains, rather than micrometeorites
or even pieces of the spacecraft knocked loose by debris.
Astronomers have suggested three sources of energy that might loosen sodium atoms from the moon's surface and generate the atmosphere: micrometeorites
, charged particles of the solar wind, or sunlight.
Even though the moon has no atmosphere, dust can be stirred up from the surface by the impact of micrometeorites
Several processes may cause Europa's icy surface to deliver small amounts of oxygen to the atmosphere -- among them sublimation (the direct change of a solid to a gas) and impacts from micrometeorites
breaking up the surface.
Scientists generally believe that the ions that make up the lunar exosphere are generated at the Moon's surface by interaction with solar photons, plasma in the Earth's magnetosphere, or micrometeorites
Because the K-T boundary sediments in the Pacific contain vast numbers of these particles, the researchers say the deposit could not have formed from the normally slow buildup of micrometeorites
There could be microbes living in the ice, but there could also be the dead bodies of microbes that used to live there, and there could be biological molecules that blew in from dust and micrometeorites
The near-nothingness of aerogels makes them well suited for collecting speeding micrometeorites
without shattering the samples, says materials scientist John F.
Several years ago, researchers discovered that this black dust actually contains micrometeorites
measuring about one-tenth of a millimeter across.