Stuff is constantly falling down on the Earth from outside its atmosphere. This might be very large rocks that we will notice to specks of dust that fall and float down. Currently, estimates of the Earth's intake of space dust vary from around five tons to as much as 300 tons every day. The Cosmic Dust in the Terrestrial Atmosphere (CODITA) project will investigate what happens to the dust from its origin in the outer solar system all the way to the earth's surface. The work, funded by the European Research Council, will also explore whether cosmic dust has a role in the Earth's climate and how it interacts with the ozone layer in the stratosphere.
Over the next five years, the scientists at Leeds, and visiting colleagues from Germany and the United States, will duplicate in the laboratory the chemical processes that dust particles undergo as they enter and filter down through the atmosphere.
"Our work in the lab will look at the nature of cosmic dust evaporation and the formation of meteoric smoke particles, which play a role in ice nucleation and the freezing of polar stratospheric clouds," said Professor Plane.
In the atmosphere, the dust particles undergo very rapid heating through collisions with air molecules, reaching temperatures well in excess of 1600 degrees Celsius. At this point they melt and evaporate. The larger particles can be seen as "shooting stars", whilst the electrons produced from ionizing collisions with air enable smaller dust particles to be detected using high-powered radar equipment.
By replicating this heating in the lab, it is hoped that radar measurements of meteors can be better understood and used to make accurate measurements of the cosmic dust input rates. The metallic vapors re condense in the atmosphere to form nanometer-sized particles known as meteor smoke.
"Cosmic dust and meteor smoke are both believed to interact with the clouds which play a key role in causing stratospheric ozone depletion - most notably the formation of the Antarctic Ozone Hole," said Professor Martyn Chipperfield, from the University's School of Earth and Environment.
"We will use the lab data in a detailed chemistry-climate model of the whole atmosphere. This will make it possible, for the first time, to model the effects of cosmic dust consistently from the outer reaches of the Solar System all the way down to the Earth's surface," said Professor Chipperfield.
"It has been suggested that to combat global warming sulfate aerosol could be released into the atmosphere to reflect some of the Sun's heat. Understanding the quantity of cosmic dust and the potential chemical reactions which may occur is crucial to moving this idea forward," said Professor Chipperfield.
The effects of aerosol on climate could be severe as noted in a study over central and northern India. It has led to a reduction in the monsoon rainfall over India in the past 50 years and above. This study was published online by the journal Science.
Recent studies of the Sahel drought and major increases since 1967 in rainfall over the Northern Territory, Kimberley, Pilbara and around the Nullarbor Plain have led some scientists to conclude that the aerosol haze over South and East Asia has been steadily shifting tropical rainfall in both hemispheres southward.
For further information see Cosmic Dust.
Meteor Trail image via Wikipedia.