(CNN)Scientists have made the first measurements of water in samples collected from the surface of an asteroid, according to a new study.
The Japanese space probe Hayabusa completed a sample return mission from the asteroid Itokawa, retrieving 1,500 particles. Another mission, Hayabusa2, is conducting a sample return mission on the asteroid Ryugu.
A study detailing the analysis of five of the particles from the asteroid samples was published Wednesday in the journal Science Advances. The samples were collected from an area on Itokawa known as the Muses Sea, which is smooth and dusty.
"We found the samples we examined were enriched in water compared to the average for inner solar system objects," said Ziliang Jin, lead study author and postdoctoral scholar in Arizona State University's School of Earth and Space Exploration, in a statement.
Each sample is only about half the thickness of a human hair, so an ion mass spectrometer was used to study the tiny mineral grains.
There was no intention to study the samples for evidence of water until two researchers from Arizona State, Jin and Maitrayee Bose, proposed it.