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NASA's fab @OSIRISREx swings by tomorrow to steal some of Earth's momentum #EarthGravityAssist, so lets chat about sampling the Solar System 
Earth’s inventory of planetary materials consists of dust & meteorites that land on Earth, & specimens from sample return missions (SRMs).
The majority of the 50,000+ classified meteorites originate from the asteroid belt between Mars & Jupiter; a few from Vesta, the Moon & Mars
Comets are thought to have formed in the cool Kuiper belt beyond the planets & the distant Oort cloud 1000x further, with temps below 40 K.
The GENESIS SRM collected solar wind to determine the Sun's composition & thus estimate the solar nebula composition curator.jsc.nasa.gov/genesis/
Moon rocks sample 9 locations: six #Apollo human SRMs brought back 2200 samples 381 kg, while three Russian Luna robotic SRMs returned 301 g
This @OSIRISREx infographic neatly shows missions that have studied/will study asteroids, including fly-bys eg @CassiniSaturn & @ESA_Rosetta
The @Hayabusa_JAXA SRM recovered ~1500 rocky particle grains, found to contain olivine, pyroxene, plagioclase and iron sulphide.
Silicaceous S-type asteroid Itokawa has the same composition as low-total-iron low-metal LL chondrites (Nakamura et al, 2011) @Hayabusa_JAXA
So @Hayabusa_JAXA showed the abundant LL meteorites come from S-type asteroids! See the 2011 Science special issue: sciencemag.org/site/feature/d…
Chondrules: 1 Building blocks of Solar System. 2 Formed as partially melted droplets. 3 Accreted to parent asteroids. 4 Found in chondrites.
The most pristine chondrules representing the early Solar System: found in carbonaceous chondrites that haven't experienced heat processing.
My friend @TimCosmos, cosmochemist & #Astronauts superstar, studies individual chondrules to determine the evolution of the solar nebula.
