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Water molecules have been detected on the surface of asteroids for the first time, proving that these remnants from the formation of our solar system are not just dried space rocks.
Astronomers believe that the impact of asteroids crashing into our planet may have helped deliver water and other elements to Earth early on, so finding evidence of water on asteroids could support that theory, according to a new study.
The data was collected from an instrument on the Stratospheric Observatory for Astronomy’s now-defunct airborne telescope. Called SOFIA, the infrared telescope flew aboard a Boeing 747SP aircraft modified to fly through the stratosphere above 99% of the Earth’s atmosphere, which blocks infrared light.
The SOFIA Telescope Far Infrared Camera, or FORCAST instrument, has allowed astronomers to detect water molecules on Iris and Massalia, two asteroids in the main asteroid belt between the orbits of Mars and Jupiter. Both are more than 223.1 million miles from the sun.
The results were published on Monday in the Planetary Science Journal.
Astronomers were encouraged to use SOFIA to study asteroids after the telescope saw evidence of water on the moon, said lead study author Dr. Anicia Arredondo, a research scientist at the Southwest Research Institute in San Antonio.
Evidence of hydration on both asteroids was previously found by study coauthor Dr. Maggie McAdam, a research scientist at NASA’s Ames Research Center in Mountain View, California, using another telescope. But researchers weren’t sure whether the hydration was caused by water or another molecular compound like hydroxyl, Arredondo said.
“Our new observations with SOFIA said definitively that what they saw was water,” Arredondo said. “But these objects are part of the S-class asteroids, which means they are made mostly of silicates, and up to the results of Dr. McAdam, assumed they were completely dry.”
Finding water on dry cosmic surfaces
The amount of water the team detected was the equivalent of a 12-ounce bottle of water trapped within a cubic meter of soil, Arredondo said, which was equivalent to finding SOFIA’s moon. The telescope detected the signature of water molecules in one of the largest craters in the moon’s southern hemisphere in 2020.
Like the water found on the surface of the moon, “on asteroids, water can bind to minerals as well as adsorb silicate and become trapped or dissolved in silicate impact glass,” Arredondo said.
Asteroids are the leftovers from when the planets formed in our solar system. Studying their composition can tell astronomers where in our cosmic neighborhood the asteroids came from.
“When the solar system was forming, different materials formed based on their distance to the Sun because material (further) from the Sun cooled down faster (than) material closer to the Sun,” Arredondo said. by email. “That’s why the inner planets like Earth and Mars are made of rock and the outer planets like Neptune and Uranus are made of ice and gas.”
If water is found on Iris and Massalia, astronomers can trace the history of these particular asteroids, suggesting that they happened to be far enough from the sun to avoid boiling their water from heat.
Searching for water throughout the solar system
The researchers tried to look for water on two other asteroids using SOFIA, but the detection was too small. Now, the team is using the James Webb Space Telescope to zero in on various asteroids and look for signatures of water.
While Webb’s observations are ongoing, Arredondo said the preliminary results prompted the team to request time to observe 30 more asteroids using the powerful infrared telescope.
“The JWST telescope is much larger than the SOFIA telescope, so it can collect data at a higher quality, and it can collect data for more asteroids in a shorter period of time,” Arredondo said. “Hopefully I’ll be able to see enough different asteroids with JWST to look for this water signature, and hopefully I’ll be able to take an inventory of the water in the asteroid belt.”
Webb could help astronomers better understand the distribution of water throughout the solar system, as well as the composition of different types of asteroids.
“We really didn’t expect to find water on these silicate-rich asteroids,” Arredondo said. “Primarily when we talk about hydration on asteroids, we’re talking about more carbon-rich asteroids, like the Bennu asteroid that NASA’s OSIRIS-REx mission went to. So now I want to look for trends between (the) amount of hydration and composition. I want to know if the carbon-rich asteroids have much more water than the silicate-rich asteroids, or if they have similar amounts.”
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