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Once again, the Hubble Space Telescope surprises the scientific community with its usefulness in the discovery Of new cosmic objects. By digging through the telescope’s archive data, ESA astronomers, as part of a participatory program involving the public, have identified more than 1,000 previously unrecorded space rocks within the solar system. This “treasure hunt” involved consulting 37,000 images archived over a period of 19 years.
To achieve this feat, volunteers called “citizen scientists” joined forces with astronomers from the European Space Agency (ESA). They thus combined their efforts using a machine learning algorithm to identify asteroids. This new approach could be applied in other research to quickly access large data spanning decades.
Towards a better understanding of the evolution of the main asteroid belt
The main asteroid belt, located between Mars and Jupiter, is home to several million asteroids of all sizes. At the heart of this belt, located approximately 2.7 astronomical units (AU) from the Sun, collisions between space rocks occur to give rise to new, smaller stars, according to the favored hypothesis.
An invitation to dream, ready to be worn.
Astronomers have long sought to unravel certain mysteries surrounding the evolution of the asteroid belt. For this, asteroids with a diameter of less than one kilometer are particularly interesting. This is why the discovery of space rocks corresponding to this criterion was the main objective of the study.
“ We are beginning to learn more about the small population of main belt asteroids. We were surprised to see such a large number of candidate objects said lead author Pablo Garcia-Martin, a researcher at the Department of Theoretical Physics at UAM in Spain, in a statement. “ There were hints of the existence of this population, but we now confirm it with a random sample of asteroid population obtained from the entire Hubble archive. It is important for understanding the evolutionary patterns of our solar system “, he said.
19 years of archived data reviewed
The research team led by Garcia-Martin included members from ESA, NASA’s Jet Propulsion Laboratory (JPL), the Astronomical Institute of the Romanian Academy, the University of Craiova, the Côte d’Azur University and Bastion Technologies. To discover these small asteroids, the team has not scheduled any new observations. Instead, she went back in time to review 19 years of images taken by Hubble.
These shots did not focus on the asteroid belt, but mainly on galaxies, stars and nebulae. Asteroid trails, however, were captured by Hubble due to its fast geocentric orbit. Typically, these space rocks go unnoticed, since they have an average brightness forty million times less than the faintest star visible to the naked eye. However, it is their imperfections that reveal them: when crossing the field of view of the telescope, they appear as small white lines (astronomers refer to them as “photobombs”).
“ The position of asteroids changes over time, and so it is not possible to find them simply by entering their coordinates, because at other times they may not be there », Explains Bruno Merin, co-author of the study. “ As astronomers, we don’t have time to review every asteroid image. This is why we had the idea of collaborating with more than 10,000 citizen volunteers to consult the immense Hubble archives “, he added.
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The Hubble Asteroid Hunter (HAH) project, launched in 2019, brought together around 11,400 citizen volunteers who analyzed more than two million images to select the most interesting ones. An algorithm was then trained to detect “photobombing” space rocks. It combed through 37,000 images in which 1701 asteroid trails were detected, including 1031 uncatalogued asteroids. Of these newly discovered asteroids, about 400 are less than a kilometer in diameter.
Given the success of this pioneering approach, astronomers suggest that this method could be applied to data sets accumulated by other asteroid-hunting observatories, such as the James Webb Space Telescope (JWST). As a next step, the HAH project will examine the streaks of previously unknown asteroids to characterize their orbits, rotation periods and other characteristics.
