Traces of water found in 17 asteroids
New Delhi : Japanese infrared satellite AKARI has discovered evidences of water in 17 asteroids. It is for the first time that scientists have found water traces which will possibly to the understanding of water distribution in our solar system. Also, the new discovery will help scientists to dig out the facts about evolution of asteroids and origin of water on Earth.
It is known to all that our Earth is an aqua-planet, and is the only planet in our solar system where the presence of water on the planet surface has been confirmed. But, a mystery remains as how the Earth acquired water.
With passing time, studies have confirmed that other celestial bodies in our solar system too have water in some form. And, asteroids are among those bodies which brought water to our planet.
Researchers from Japan Aerospace Exploration Agency (JAXA) and University of Tokyo found that water stays in asteroids as hydrated minerals, which were produced by chemical reactions of water and anhydrous rocks that occurred inside the asteroids.
As per the Publications of the Astronomical Society of Japan, hydrated minerals are stable even above the sublimation temperature of water ice. By analyzing hydrated minerals, scientists can investigate whether asteroids have water.
Infrared wavelengths have characteristic spectral features of various substances, such as molecules, ice, and minerals, which cannot be observed at visible wavelengths. Therefore, it is crucial to observe at infrared wavelengths for the study of solar system objects.
Hydrated minerals exhibit diagnostic absorption features at around 2.7 micrometres. The absorption of water vapour and carbon dioxide in the terrestrial atmosphere prevents us from observing this wavelength with ground-based telescopes.
Conversely, the Infrared Space Observatory (ISO), launched in 1995, did not have a sufficient sensitivity to make spectroscopy of faint asteroids. The Spitzer Space Telescope, launched in 2003, did not have coverage of this wavelength range. Therefore, it has not fully been known how much water is contained in asteroids.
The Japanese infrared satellite AKARI was launched in February 2006 and ended operations in 2011. It was equipped with the Infrared Camera (IRC) that allowed scientists to gather spectra at near-infrared wavelengths from two to five micrometres.
