mikromeetrit

Mikromeetrit, eller micrometeorites, are small extraterrestrial particles that reach Earth’s surface. Most are less than a millimeter in diameter, though some may be larger. They originate from comets and asteroids and are remnants of the dust and debris that populate the inner solar system. During atmospheric entry they experience heating and melting, often forming glassy rims or fusion crusts; many retain glassy spherules with relict mineral grains embedded in a melt-derived matrix. A common distinction is between glass-rich micrometeorites and iron-bearing micrometeorites, though samples frequently show mixed textures.

Where they are found and collected: Micrometeorites are recovered from clean environments such as Antarctic and Greenland snow, deep-sea sediments, and, in some cases, collected from the stratosphere using high-altitude aircraft or balloons. To study them, scientists use meticulous cleaning and separation procedures to remove terrestrial contamination, followed by chemical and mineralogical analyses. Techniques include scanning and transmission electron microscopy, X-ray spectroscopy, and isotopic measurements. Some micrometeorites contain pre-solar grains, while others bear isotopic and mineralogical signatures that point to cometary or asteroidal sources. The textures and mineralogy provide clues about high-temperature condensation, subsequent alteration, and the delivery of organic and volatile materials to early Earth.

Significance: Micrometeorites offer direct samples of cosmic dust that complement meteorites and space missions. They help constrain the flux of extraterrestrial material to Earth, illuminate the building blocks of planets, and contribute to understanding the early Earth’s environment and the solar system’s formation processes.