The European Space Agency’s Hera spacecraft has captured its first view of the Didymos asteroid system in which the larger Didymos and its smaller companion, Dimorphos, appear as separate objects. The image marks a major milestone in Hera’s approach to the site of NASA’s historic asteroid-deflection experiment, which scientists hope will reveal how the 2022 impact changed Dimorphos.
The asteroid pair is currently approximately 197 million kilometers from Earth. Hera used its black-and-white asteroid-framing camera to acquire the image on the night of October 18, when the spacecraft was about 1,280 kilometers from its target. The image was captured by an in-vehicle camera.
“This image allows us to see the smaller Dimorphos asteroid for the first time,” explains Michael Küppers. “Prior to this acquisition, the spacecraft was still resolving the Didymos system as a single point. But now, although Dimorphos consists of only about one pixel in this initial image, it is clearly well separated from its parent object.”
Hera approaches the two asteroids
The image follows a series of maneuvers designed to slow Hera as it approaches the asteroid system. In early October, the spacecraft fired its thrusters twice, with one maneuver taking place a week after the other. These adjustments reduced Hera’s velocity relative to the asteroids to just 20 meters per second, allowing mission controllers to carefully manage the rest of the approach.
Although the asteroids appear small in the first image, they are substantial objects. Dimorphos has a diameter of approximately 151 meters, making it roughly the same size as the Great Pyramid of Giza. Its larger companion, Didymos, is about 780 meters in diameter—slightly less than the height of Dubai’s Burj Khalifa, the world’s tallest building.
Dimorphos travels an average distance of just 1.15 kilometers around Didymos, moving at approximately 18 centimeters per second.
Mission manager Ian Carnelli added: “For the first time, we are seeing the very double asteroid system for which this mission was designed and built, through Hera’s own eyes.”
“As Hera approaches, our view will become clearer. We will publish the first detailed images of Dimorphos, the solar system’s first object whose orbit has been visibly altered by human action, on November 25.”
Investigating the aftermath of NASA’s asteroid impact
Hera’s arrival will give scientists an opportunity to examine the results of a groundbreaking planetary-defense experiment conducted four years ago.
On September 26, 2022, NASA’s Double Asteroid Redirection Test (DART) spacecraft intentionally collided with Dimorphos at approximately 6.1 kilometers per second. The impact sent debris as far as 10,000 kilometers into space and shortened Dimorphos’s orbit around Didymos by about 33 minutes.
The experiment demonstrated that a spacecraft can intentionally alter an asteroid’s motion, an achievement with potentially significant implications for protecting Earth from future asteroid threats.
However, the collision also produced results that scientists are still working to explain. The change in Dimorphos’s orbit was much larger than predicted by computer simulations, raising questions about the physics of the impact and the asteroid’s response.
Researchers do not yet know whether DART left a crater on Dimorphos or significantly changed the asteroid’s overall shape. Understanding why the collision was so effective will require more precise measurements of the asteroid’s composition, internal structure and mass.
Answering these questions is essential to turning the “dynamic impact” approach into a credible planetary-defense strategy.
Hera prepares for a detailed investigation
Over the next few months, Hera will conduct a detailed “crash site investigation” to determine what NASA’s impact did to Dimorphos.
The spacecraft will use an array of scientific instruments to study the asteroid and its surroundings. It also plans to deploy two small satellites, known as CubeSats and roughly the size of shoeboxes, to collect additional observations from closer range. The investigation is eventually expected to include a landing operation.
These measurements should help scientists better understand how asteroids respond to high-speed impacts and improve predictions of how future deflection attempts will work.
Introducing Hera Space Companion
Anyone interested in following Hera’s journey can explore the mission through the Hera Space Companion. This interactive communications platform is more mission-focused than traditional AI chatbots and is designed to make the European Space Agency’s first planetary-defense mission accessible to the public.
Source: www.sciencedaily.com
