Two teams of astronomers have been able to observe the effects of a NASA probe hitting an asteroid thanks to the Large Telescope (VLT) installed in Chile by the European Southern Observatory (ESO).
DART (Double Asteroid Redirect Test) probe It collided with the asteroid Dimorphos at a distance of 11 million km from Earthin a controlled test for planetary defense, the Garching (Germany)-based organization said in a statement.
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The results of the VLT’s observations have now been published in two science papers that aim to shed light on the asteroid’s composition based on the material released by the impact.
A team around astronomer Cyrielle Opitom, from the University of Edinburgh (UK), examined the evolution for a month of the cloud of fragments released by the Dimorphs, which turned out to be bluer than the asteroid itself before impact. They also studied other structures, including the red spirals, that formed in the days after the collision.
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Using an instrument known as the Multi-Unit Spectroscopic Explorer, they split the light from the cloud into a rainbow-like pattern and looked for chemical signatures that revealed traces of ice, which they did not find. “Asteroids are not expected to contain large amounts of ice, so detecting any trace of water would be a real surprise,” Opitome said.
The team also tried to find traces of fuel from the lander, but was unable to find it; The possibility that it was “remote”, the astronomer calculated, because the amount of gas remaining in the tanks of the ship’s propulsion system was small.
Another group of researchers led by Stefano Bagnolo of the Armagh Observatory and Planetarium (UK) examined how the surface of Dimorphos was altered by the collision.
Bagnulo showed that when sunlight is scattered by the surface or atmosphere of a celestial body, it becomes polarized; That is, it does not oscillate randomly but in a preferred direction, and changes in polarization can reveal information about an object’s structure and composition.
In the case of the Dimorphs, they found that the level of polarization dropped sharply, while the overall brightness increased. “The material mined by the impact was probably brighter and less polarized than the material at the surface, as it was never exposed to the solar wind or solar radiation,” he said.
Another option is that the particles released from the collision were smaller than those from the asteroid’s surface and therefore reflect light better, as they do under certain conditions. In any case, Opetum stressed, the observations were made taking advantage of a “unique” chance, since it is not possible to predict in advance when collisions between asteroids will occur naturally and in which case, thanks to the DART probe, this was possible. It can be studied ‘almost as if it were a laboratory.