Particle Diary
Oldest object in solar system
Scientists believe the particles acted as tiny travel diaries, tracing their journey through the early solar nebula
Very recently scientists, with the aid of Lawrence Livermore's NanoSIMS-LLNL (nanometer-scale secondary-ion mass spectrometer) found tiny grains of dust of from a meteorite which are proving to be the earliest specimens of the primordial solar system, referring to a time before the Earth was born. It must be mentioned here that LLNL is an instrument that can analyze samples with nanometer-scale spatial resolution. And LLNL scientists in conjunction with NASA Johnson Space Center, University of California, Berkeley and the University of Chicago, have found particles called calcium-aluminium rich inclusions or CAI inside meteoroids which scientists believe is 4.6 billion-year old and acted as tiny travel diaries, tracing their journey through the early solar nebula. The discovery, of which details have been published in the March 4 issue of the journal Science, was led by Dr. Justin Simon, an astro-materials specialist with NASA's Johnson Space Center in Huston. And Dr. Simon chose a pea-size CAI from the Allende meteorite (that crash-landed in Mexico in 1969), the largest carbonaceous ever found on Earth. According to LLNL scientist, Ian Hutcheon, "Allende is this very unusual meteorite with all these wonderful inclusions (CAIs). The isotopic measurements indicate that this CAI was transported among several different nebular oxygen isotopic reservoirs, arguably as it passed through into various regions of the proto-planetary disk". Few words on CAI are in order. Roughly millimeter-to-centimeter in size, CAIs are believed to have formed very early in the evolution of the solar system and had contact with nebular gas, either as solid condensates or as molten droplets. And relative to planetary materials, CAIs are enriched with the lightest oxygen isotope and are strongly believed to record the oxygen composition of solar nebular gas where they grew. Also CAIs, at 4.6 billion years old, are in fact millions of years older than more modern objects in the solar system, such as planets, which formed about 10-50 million years after CAIs. And since CAIs were among the very first solids to condense from the swirl of gas and dust as the planets were forming, according to researchers, it is fairly logical to study them in order to yield clues about our solar system's early days. Measuring the two different oxygen isotopes (oxygen-16 & oxygen-17) in space rock's various layers and by analyzing their relative abundances in the different parts of the CAI, the scientists were able to learn a great deal about its travel pattern and history, which turned out to be quite extensive. The findings of the research led to this conclusion that CAIs formed from several oxygen reservoirs, likely located in distinct regions of the solar nebula. It was also found that CAIs traveled within the nebula by lofting outward away from the sun and then later falling back into the mid-plane of the solar system or by spiraling through shock waves around the sun. According to Dr. Simon, "If you were this grain, you formed near the proto-sun, then likely moved outward to a planet-forming environment, and then back toward the inner solar system or perhaps out of the plane of the disk. Of course, you ended up as part of a meteorite, presumably in the asteroid belt, before you broke up and hit the Earth".
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