Divert the trajectory of an asteroid on a collision course with the Earth, by means of a controlled impact at full speed with a space probe. This was the challenge of the DART mission (Double Asteroid Redirection Test) by NASA, successfully completed on 26 September 2022, in which Politecnico was directly involved as part of the scientific team.

The first scientific results on the DART Mission have been published in the authoritative journal Nature in three different articles, co-authored by the researcher Fabio Ferrari from the Department of Aerospace Science and Technology at the Politecnico di Milano.

The article ‘Successful Kinetic Impact into an Asteroid for Planetary Defense’, describes the successful test of kinetic impact technology on the asteroid Dimorphos. The DART mission was the first to test this technology at full scale, demonstrating that it is an effective technique for planetary defence against possible asteroid threats.

The study ‘Ejecta from the DART-produced active asteroid Dimorphos’, describes the observations made using the Hubble Space Telescope on the material ejected by the impact of DART with the asteroid Dimorphos. The observations showed a complex morphology of the ejecta, conditioned by the gravitational interaction between the asteroid and the dust under the influence of solar radiation pressure.

Finally, the effectiveness of the kinetic impact of a satellite in avoiding a potential collision with the Earth is demonstrated in ‘Momentum Transfer from the DART mission Kinetic Impact on Asteroid Dimorphos’ co-authoredby the professor of Flight Mechanics at the Politecnico, Michele Lavagna. The article quantifies the deflection effect produced by the high speed impact on the orbit of the binary system Didymos, showing how the ejection of the fragments generated by the impact helped to increase the efficiency of the energy exchange between the probe and the asteroid.

“DART is a historic moment for space exploration: it is not only the first planetary defence test, but it is also the first time we visit a binary asteroid (a system where two asteroids orbit around a common centre of gravity) and where we have the opportunity to observe how an asteroid can react to an external stress,” explains Fabio Ferrari, co-author of the scientific studies on DART.

This has allowed us – and will allow us again in the coming months – to study the structure and evolutionary history of these celestial bodies, so close to us but still barely known. The Politecnico di Milano is part of the scientific team of the DART mission and has contributed to studying the evolutionary dynamics of the Didymos binary system.

These include the motion and stability of the binary system, as well as the internal structure of the two asteroids Didymos and Dimorphos. The Politecnico has also played a decisive role in the characterization of the motion of the fragments ejected following the impact, and their morphology observed through orbital and Earth-based telescopes.”

“It is the first time that an attempt has been made to divert a celestial body from its natural orbital path in a perceptible and significant way and to measure its effectiveness,” adds Michele Lavagna. And it is above all the first time that the impact has been witnessed by an extremely small satellite, LICIACube, the first European probe to travel in deep space.

It played a fundamental role in acquiring images during and after the DART impact: images that helped us to understand the composition and structure of Dimorphos and the dynamics of the binary asteroid system, having recorded the sequence of formation of the fragments post impact and their expansion into the surrounding space in the minutes following the collision by DART.

The Politecnico di Milano, together with the Italian National Institute of Astrophysics (INAF), contributed to the design and guidance of this small scientific satellite and is actively involved in the scientific analysis of the images acquired to reconstruct the evolution of the motion of the fragments generated.”

The Johns Hopkins Applied Physics Lab built and operated the DART spacecraft and manages the DART mission for NASA’s Planetary Defense Coordination Office as a project of the agency’s Planetary Missions Program Office. For more information about the DART mission, visit https://www.nasa.gov/dart or https://dart.jhuapl.edu . Neither Dimorphos nor Didymos poses any hazard to Earth before or after DART’s controlled collision with Dimorphos

Politecnico di Milano is a scientific-technological university which trains engineers, architects and industrial designers.

The University has always focused on the quality and innovation of its teaching and research, developing a fruitful relationship with business and productive world by means of experimental research and technological transfer.
Research has always been linked to didactics and it is a priority commitment which has allowed Politecnico Milano to achieve high quality results at an international level as to join the university to the business world. Research constitutes a parallel path to that formed by cooperation and alliances with the industrial system.

Knowing the world in which you are going to work is a vital requirement for training students. By referring back to the needs of the industrial world and public administration, research is facilitated in following new paths and dealing with the need for constant and rapid innovation. The alliance with the industrial world, in many cases favored by Fondazione Politecnico and by consortiums to which Politecnico belong, allows the university to follow the vocation of the territories in which it operates and to be a stimulus for their development.

The challenge which is being met today projects this tradition which is strongly rooted in the territory beyond the borders of the country, in a relationship which is developing first of all at the European level with the objective of contributing to the creation of a single professional training market. Politecnico takes part in several research, sites and training projects collaborating with the most qualified European universities. Politecnico’s contribution is increasingly being extended to other countries: from North America to Southeast Asia to Eastern Europe. Today the drive to internationalization sees Politecnico Milano taking part into the European and world network of leading technical universities and it offers several courses beside many which are entirely taught in English.

Mascia Sgarlata

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