DOM 08006 grains hold a 150 to 600 microtesla cloud field as falling rocks melt 40 per cent
Inclusions from DOM 08006 carry a field of 150 to 600 microteslas from the solar system's first 200,000 years. Across 75 filmed falls, a rock can lose 40 per cent of its mass to melting before it fragments.
Science··Morning
DOM 08006 grains carry 150 to 600 microteslas
Calcium aluminium rich inclusions from DOM 08006, formed within the solar system's first 200,000 years, carry a magnetic field of 150 to 600 microteslas, or 3 to 12 times Earth's present field, in a paper in Proceedings of the National Academy of Sciences. A field that strong fits models in which magnetic braking drains angular momentum and lets a spherical cloud settle into a protoplanetary disc. The measurement comes from a group at MIT with lead author Cauê Borlina, now at Purdue University.[1]
The inclusions vary inside a single millimetre
Benjamin Weiss of MIT calls the shift from a spherical cloud to a protoplanetary disc one of the most significant events in solar system history. The team cautions that calcium aluminium rich inclusions vary even within a single millimetre of the meteorite, so identifying which grains carry an unaltered signal is part of the result.[1]
A falling rock loses 40 per cent of its mass to melting
Peter Jenniskens and colleagues at the SETI Institute and NASA Ames analysed 75 meteorite falls captured on video and in photographs, and split atmospheric entry into seven phases in Meteoritics & Planetary Science. Melting, then fragmentation, governs how a rock sheds mass, with fragmentation starting at air pressures about one fifth of the measured strength of meteorites. A falling rock can lose 40 per cent of its mass to melting before it fragments. The fastest spinning rocks complete a rotation every 0.5 to 5 seconds. Fragments above 20 grams scatter more widely, while smaller meteorites land in a narrow strip, as Darrel Robertson at NASA Ames puts it. The 2013 Chelyabinsk asteroid, about 20 metres across, sits at the far end of the same physics.[2]
