NEWS | Europe’s Hera spacecraft has taken its first picture that shows the asteroids Didymos and Dimorphos as two separate objects. The photo was taken on October 18 from about 1,280 kilometers away. The pair is about 197 million kilometers from Earth. Dimorphos shows up as just one tiny dot, but it now sits clearly apart from its bigger partner.
Didymos is about 780 meters wide. Dimorphos is about 151 meters wide, close to the size of the Great Pyramid of Giza. They circle each other about 1.15 kilometers apart. Until now the spacecraft saw them as one point of light. In October, Hera fired its thrusters twice to slow down. It is now moving at about 20 meters per second compared with the pair.
What DART left behind
In September 2022, NASA’s DART spacecraft crashed into Dimorphos at about 6.1 kilometers per second. The hit threw debris as far as 10,000 kilometers into space. It also cut about 33 minutes from the time the small asteroid takes to circle Didymos. That change was much bigger than computer models had predicted. Scientists still do not know if the crash left a crater or changed the rock’s shape.
Hera is there to find answers. Over the coming months it will study what Dimorphos is made of, how it is built inside and how heavy it is. It will also release two small satellites, each about the size of a shoebox, to take a closer look. Landing is expected to follow later. The first detailed pictures of Dimorphos are due on November 25 and should be much sharper than this one.
In BMN’s view, this is the missing half of the experiment. DART showed that a spacecraft can push an asteroid off its path. To use that idea for real, scientists need to know how far a rock will move for a given hit. Hera’s measurements could give them that, and help future missions plan with more confidence.
If a dangerous asteroid ever heads our way, will we know exactly how hard to hit it?
