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"We found that the samples we examined were enriched in water compared to the average of the internal solar system objects," said Ziliang Jin, lead author of the study and postdoctoral researcher at the school. Exploration of the Earth and the space of Arizona State University.
Each sample representing only half the thickness of a human hair, an ion mass spectrometer was used to study the tiny mineral grains.
There was no question of studying the presence of water in the samples until two researchers from the state of Arizona, Jin and Maitrayee Bose, proposed it.
In two of the five particles, Jin and Bose found pyroxene, a mineral known to contain water. Further study showed that the samples were rich in water, although Itokawa is dry.
Itokawa is an S-type asteroid, one of the most common objects of the asteroid belt. Even if these objects are small, they also retain the materials with which they were formed.
"They initially formed at a distance of one-third to three times the distance from the Earth," Bose said.
Itokawa has the shape of a peanut and orbits around the sun every 18 months, swaying in the orbit of the Earth and then beyond Mars. The asteroid is 1,800 feet long and between 700 and 1,000 feet wide.
The asteroid looks like a pile of rubble held together by force. It is a fragment of a much larger body that was once 12 miles wide, but it has undergone brutal changes. At one point, he encountered high temperatures that heated him to 1,000 or 1,500 degrees Fahrenheit. Several impacts eventually broke it.
Two of the fragments, called lobes, merged about 8 million years ago. The researchers believe that the samples were buried at least 328 feet inside the much larger parent body before it broke.
When the asteroid is broken into pieces, it is likely that the sample grains have been exposed to radiation and micrometeorite impacts. And yet, they hold back water. The composition of minerals is similar to that of the Earth.
"It means S-type asteroids and the parent bodies of [non-modified asteroids] are probably a critical source of water and several other elements for terrestrial planets, said Bose. This makes these asteroids high priority targets for exploration. "
Both researchers believe that asteroids like this, which had an impact on the Earth at the beginning of its history, could have provided up to half of the water in our oceans, according to the report. ;study.
This tells us not only the planets of our own solar system, but also what we might find outside of it.
"Returning sample missions are mandatory if we really want to do a thorough study of planetary objects," Bose said. "The Hayabusa Mission in Itokawa has expanded our knowledge of the volatile content of the bodies that have contributed to the formation of the Earth.It would not be surprising if a similar mechanism of water production is common to rocky exoplanets. surrounding other stars. "
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