Sent in by Gary – see www.centauri-dreams.org/2021/04/12/dustfall-earths-encounter-with-microm… … encounters between the earth and space dust. Or in this instance what they call micrometeorites. The research made use of the pristine snow of Antarctica to find out how much space dust could be found in a chosen square of land. The snow aided the discovery of the particles as it is white and space dust comes in at a darker hue. The exercise enabled them to predict how much space dust collided with earth per each square metre of land – each year. It was then interpolated over the whole of the earth, with remarkable results [assuming what falls at the poles is what falls at the tropics etc.]. A vital part of the research was the heating up of the particles as they fell through the atmosphere – although some particles may have failed to reach the ground. The heating, in general, converted most particles into nm-sized particles known as meteoric smoke. The particles are transported by atmospheric circulation until eventually dropped at the surface. Rain might play a role.
The research is fascinating as they also used data from the Long Duration Exposure Facility satellite which spent 5 years orbiting the earth to measure the effects of micrometeorites, space debris, radiation particles, atomic energy – and solar effects. The idea was to explore their impact on spacecraft [the materials they are constructed from, components and systems, as well as space shields]. The findings were retrieved by the Space Shuttle STS-32 mission as long ago as 1990. The panel on the satellite allowed them to measure indentations caused by high velocity sub millimetre grain. The research was published this month in Earth and Planetary Science Letters – see www.sciencedirect.com/science/article/pii/S0012821X21000534?via%3Dihub … or https://doi.org/10.1016/j.epsl.2021.116794 … it seems between 20 and 100 tons of the stuff falls to earth each year. A quarter of it is thought to have an origin in comets [outgassing events, break ups, flare ups etc]. That leaves a lot of stuff with an origin elsewhere.