Interplanetary Dust Particle Found

A new interplanetary dust particle has been collected and identified as part of NASA's Stardust mission. Called "brownleeite," the mineral was shed from the tail of a comet that periodically orbits the sun. It is named for Dr. Donald Brown of the University of Washington, who founded the field of interplanetary dust particle research.

Brown is also the lead scientist of NASA's Stardust mission (1999) that successfully collected comet dust material in space and returned it to Earth for analysis. Scientists look for the two predicted silicate materials known as amorphous silicates and crystalline silicate enstatite. Brownleeite is neither of these predicted silicates.

Strangely enough, the Earth is covered with interplanetary dust. Earth collects 40,000 tons of this dust every year. Perhaps not star dust, these tons of dust are from comets and asteroids and sprinkle down through the upper atmosphere to the planet. But the infiltrating veil of interplanetary dust is so fine that collecting it is quite the trick.

High-altitude research aircraft have been collecting this dust for NASA since 1982. In 2003, a dedicated effort was made because scientist Scott Messenger of Johnson Space Center correctly predicted that comet 26P/Grigg-Skjellerup, which orbits the Sun every five years, would be a source of dust grains as it past between Earth and the Sun at a particular time of year. And in April of 2003, the research aircraft did indeed collect interplanetary dust particles (IDPs) shed from the comet.

It was in this sampling that the new mineral was found. IDPs are considered to be of the utmost importance because they are believed to be material from the original building blocks of the Solar System.

The mineral, one never seen before, combines manganese and silicon and is called a manganese silicide. Other minerals that are known only from their presence in extraterrestrial rocks were found forming multiple layers around the manganese silicide, which is the newest addition to a list of 4,300 known minerals. Brownleeite is a substance that science had not predicted as a component of interplanetary comets or as a result of early solar nebula condensation.

Minerals are natural compounds of inorganic matter--neither plant nor animal--that have a definite chemical composition and are formed through geological processes. The new brownleeite is so tiny, as are all IDPs, that the minerals' chemical composition and crystal structure can only be measured through state-of-the-art nanotechnology and analysis techniques.

Dr Emily Baldwin: http://astronomynow.com/080613Anewtypeofcometdustmineral.html

NASA Stardust: http://www.nasa.gov/mission_pages/stardust/main/index.html

wordnet.princeton.edu/perl/webwn

en.wikipedia.org/wiki/Mineral