ESA's Hera Mission: Aiming to Unveil Secrets of Dimorphos and Didymos Asteroids
At 1652 today, Italian time, the European Space Agency's (ESA) Hera mission successfully launched from Cape Canaveral, Florida, to study the conditions of Dimorphos, the asteroid previously impacted by NASA's Double Asteroid Redirection Test (DART) in the autumn of 2022. The launch utilized a Falcon 9 rocket from private space company SpaceX, which proceeded despite challenging weather conditions typical of hurricane season. Hera is expected to journey for approximately two years to reach its destination, located about 195 million kilometers from Earth.
The Hera mission is closely tied to the earlier DART mission, which aimed to test the potential for asteroid deflection to prevent future catastrophic collisions with Earth. DART achieved this by colliding with Dimorphos, a small asteroid with a diameter of 151 meters, which orbits a larger asteroid, Didymos, measuring 780 meters across. The impact was successful, altering the orbital period of Dimorphos, which is the time required for it to complete an orbit around Didymos. The change exceeded initial expectations and was confirmed using multiple ground-based telescopes. However, to gain deeper insights, closer observations were essential given the vast distance separating them from Earth.
Hera’s mission is to provide detailed observations and measurements of both asteroids, offering fresh insights into the effects of the DART impact as well as the intrinsic properties of these celestial bodies. Upon reaching Dimorphos and Didymos in October 2026, Hera will deploy sophisticated instruments to analyze their shape, mass, and motion while maintaining a distance of 20 to 30 kilometers from their surfaces for initial studies. In a subsequent phase, Hera will maneuver closer, about 8 to 10 kilometers away, to conduct an in-depth examination of their surface characteristics, ultimately aiming for a closer pass to detect the DART impact site and possibly attempt a landing on Didymos. This final segment of the mission is experimental and may not achieve its target due to the size and nature of the asteroid.
Weighing approximately one ton and designed with a nearly cubic shape of 16 x 16 x 17 meters, Hera will be solar-powered, with deployed solar panels providing an area of 13 square meters for energy collection. The mission also includes two CubeSats named Juventas and Milani, which are compact satellites aiding in additional measurements and testing new communication systems. Juventas is intended to assess the gravitational effects exerted by the asteroids, while Milani, named in honor of the renowned astronomer Andrea Milani Comparetti, aims to gather data about the surface composition and the presence of dust resulting from DART's impact.
The mission’s overall cost is estimated at 350 million euros, involving contributions from 18 ESA member states and over 100 European companies, including notable Italian firms like Avio, Leonardo, Tyvak International, and TSDSpace.
Asteroids, orbiting the sun in vast numbers, are remnants of the protoplanetary disk from which the solar system's planets formed billions of years ago. Primarily located in the main asteroid belt between Mars and Jupiter, most asteroids are positioned at a safe distance from Earth. However, certain events can disrupt their orbits, prompting them to approach our planet—these are closely monitored due to the potential threat they pose.
Recent advancements in asteroid detection and tracking have cataloged nearly ten thousand near-Earth objects (NEOs) with diameters of at least 140 meters. While no known asteroid currently poses a direct threat to Earth for the next century, preparedness remains critical.
Promising techniques for asteroid deflection have been explored, with kinetic impactors being the most prominent approach. This method involves striking an asteroid with a probe while it is still far from Earth to alter its path. DART has successfully demonstrated the feasibility of this approach on a small scale, providing a real-world experiment that surpasses computer simulations. Hera will contribute significantly by enhancing our understanding of the DART impact outcomes, allowing researchers to develop more reliable strategies for planetary defense.
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