An international team of scientists has studied both the water and organic contents from a dust particle recovered from the surface of the near-Earth S-type asteroid 25143 Itokawa by JAXA’s Hayabusa mission, which was the first mission that brought pristine asteroidal materials to Earth.
“Understanding the earliest chemical reactions involving liquid water provides crucial insights to how simple building blocks of organic compounds evolved into increasingly complex macromolecules via actions of water,” said lead author Dr. Queenie Chan from the Department of Earth Sciences at Royal Holloway and colleagues.
“Such investigation necessitates the availability of pristine samples of astromaterials — samples that have not been compromised by terrestrial contamination, and thus preserve the intrinsic states of the materials’ physical, chemical, organic and other properties.”
“Studying freshly collected, cleanly curated astromaterials returned by spacecraft reduces the ambiguity of terrestrial exposure that meteorite samples have typically experienced.”
In 2010, the Hayabusa mission successfully recovered over thousands of regolith particles, with sizes ranging 10-200 μm, from the near-Earth asteroid Itokawa.
“Itokawa is considered a rubble-pile asteroid that was re-accreted from materials of a formerly large, thermally metamorphosed, collisional-disrupted precursor planetesimal,” the researchers said.
“S-type asteroids are among the most common objects in the inner asteroid belt, where the majority of Earth’s meteorites — ordinary chondrites — came from.”
“Ordinary chondrites typically have low organic contents. Hence, their organic analyses had been challenging, which is more so in the case of minute-sized returned samples of small total recovered mass.”