Asteroid samples collected by Japanese spacecraft Hayabusa showed new clues indicating the abundant presence of water on ancient asteroid Itokawa.
The results of the study are crucial in understanding the origin of water in terrestrial planets, especially Earth.
Water On Asteroid
"We found the samples we examined were enriched in water compared to the average for inner solar system objects," said Ziliang Jin, a postdoctoral scholar from Arizona State University's School of Earth and Space Exploration and lead author of the study
Jin and fellow cosmochemist Maitrayee Bose suggested the probe of water on Itokawa samples. The five asteroid particles they studied came from the Japan Aerospace Exploration Agency.
Each sample measures only about half the thickness of a human hair, so the scientists used a Nanoscale Secondary Ion Mass Spectrometer or NanoSIMS, which can measure tiny mineral grains with great sensitivity.
In two of the five particles analyzed, the team identified the mineral pyroxene. They also found water in the crystal structure of pyroxene in the terrestrial samples. The findings suggest that even nominally dry asteroids such as the Itokawa could have harbored more water than previously thought.
"The minerals have hydrogen isotopic compositions that are indistinguishable from Earth," according to Jin, who also said that the minerals from the asteroid still show evidence of water that has not been lost to space when Itokawa's parent body met a catastrophic collision.
Water On Earth Came From Asteroids?
Based on the study, Earth is characterized by high water abundances in its crust and mantle. However, the origin of water in the inner solar system bodies is constantly debated.
Other scenarios possibly explaining Earth's water sources include the gradual accumulation of ice in pebble-sized bodies as the snow line migrated and the ingassing of molecular hydrogen by growing planets.
Bose said the Hayabusa mission to Itokawa has expanded existing knowledge of the volatile contents of the bodies that helped form Earth.
Probing Itokawa
Itokawa 25143 also known as Itokawa, is an S-type asteroid. This asteroid type is generally small and among the most common objects in the inner part of the asteroid belt. These space rocks are believed to have recorded and possibly retained information about primordial nebular water.
According to NASA, Itokawa was discovered on Sept. 26, 1998, by the Lincoln Laboratory Near-Earth Asteroid Research Team at Socorro, New Mexico. JAXA's Hayabusa mission touched down twice on Itokawa in 2005. In June 2010, the probe brought back for analysis more than 1,500 particles from Itokawa's Muses Sea, a smooth and dusty area on the asteroid.
Scientists believe that Itokawa is a remnant of a much larger space object that was shattered by a collision some 8 million years ago. This asteroid has two main lobes resembling a pair of rubble pile loosely held together by mutual gravity.
The ASU study is published in the journal Science Advances.
