Artist’s illustration of the projection of a cloud of debris after NASA’s DART spacecraft collided with the asteroid Dimorphos.© ESO/M. Grain fairs
The European Southern Observatory (ESO) released images of the impact of NASA’s pioneering DART mission, which on September 26 last made history when it collided with the asteroid Dimorphos. This one, which previously took 11h55 to revolve around a larger asteroid, Didymos, now takes less time, 11h23.
The impact took place 11 million kilometers from Earth, which is considered close enough to be observed in detail by large telescopes. ESO astronomers seized on the historic opportunity to observe the aftermath of the collision with the four 8.2-metre telescopes at the Paranal Observatory in Chile.
As ESO reports, the first results of these Very Large Telescope observations have now been published in two papers.
Cyrielle Opitom, an astronomer at the University of Edinburgh and lead author of one of the papers, followed the evolution of the debris cloud for a month with her team using the Multi Unit Spectroscopic Explorer (MUSE) instrument on ESO’s Very Large Telescope.
Set of images shows the evolution of the debris cloud formed after the collision of DART with the asteroid, in the space of a month.© ESO/Opitom et al.
In this way they verified that the cloud was bluer than the asteroid itself before the impact, indicating that the cloud could be made of very fine particles.
In the following days, other structures developed, such as spirals and a long tail pushed by the Sun’s radiation, and redder than the initial cloud, and therefore could be made of larger particles.
“DART is really a great opportunity to study a controlled impact, almost like in a lab,” said Opitom.
Another team, led by astronomer Stefano Bagnulo, studied how the DART impact altered the asteroid’s surface. They found clues that suggest the impact exposed purer material from the asteroid’s interior. Another possibility is that the impact destroyed particles on the surface, projecting much smaller particles into the debris cloud.
Further investigations are ongoing, ESO said.
“Very close” asteroid
These articles are made public at a time when a large asteroid, designated 2023 DZ2 passes “very close” to Earth, more specifically 168,000 kilometers from Earth, at a speed of 28,000 km/h. Due to its size, about 50 meters, according to NASA’s estimate, if it entered the Earth’s surface it could destroy a city.
It was sighted for the first time on February 27th by an observatory located in La Palma, Canary Islands.
While small asteroids pass close to Earth every day, an object of this size passing so close to our planet is an event that happens once a decade, commented Richard Moissl, head of a planetary defense office at the European Space Agency. (ESA).
Still according to Moissl, there are more than 1450 near-Earth objects on a “risk list”, which are under constant observation.
