Crazy surprise! Asteroid 'Dinky' is not binary but a group of 3 space rocks, NASA's Lucy probe finds

Asteroid Dinkinesh, the first cosmic site of NASA's Lucy spacecraft is full of surprises that have left scientists spellbound once again.

Earlier it was found that Dinkinesh, also called "Dinky" sometimes, is actually a binary unit made of two moons, the other one being a tiny shadow of Dinky. This tiny natural satellite was named Selam by NASA's Lucy mission team.

Now, in another revelation, it has been found that Selam isn’t a single moon, as analysed by Lucy mission experts. In other words, Selam is the first contact-binary-asteroid-moon situation. Crazy, right?

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The analysis of Lucy's observations of Dinkinesh and Selam was published in Nature Wednesday.

Asteroid Dinky's binary Selam is itself a binary unit!

Dinky's binary Selam appears to be two objects, or lobes, which are in close contact with each other. They are of similar size- one lobe is about 230 yards (210 meters) across and the other is 250 yards (230 meters) across.

Selam is tidally locked to Dinkinesh, meaning one lobe permanently remains closest to the larger asteroid.

Take a look at the new image of Asteroid Dinky by NASA's Lucy spacecraft.

“There’s a lot more complexity in these small bodies than we originally thought,” says University of Maryland astrogeologist Jessica Sunshine.

“With the additional observations taken by the spacecraft, we were able to better analyse features such as Dinkinesh’s rotation speed and Selam’s orbit pattern.”

The larger asteroid of the three space rocks, Dinkinesh has a strange large trough that runs longitudinally around it, according to a team led by the mission's principal investigator, Hal Levison of the South-west Research Institute in Boulder, Colorado.

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It also has an equatorial ridge that is overlaid on top of that trough and wraps around its rotational axis. Levison's team explains that these features are the result of a massive structural calamity.

The resulting centrifugal force on Dinkinesh then caused some material to lift off the surface of the spinning asteroid, scientists have now learned. That material then settled into a ring of debris around the asteroid's equator.

Some of the material spun off from Dinkinesh fell back onto the asteroid, forming the equatorial ridge on it, while the rest came together to form two satellites.

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The likeness of the size of the two lobes intrigues Levison as he wonders whether this is telling something more about the process of formation of the satellite.

Regardless of the mystery, once the two halves of Selam were formed, they must have edged closer and closer together, moving at very low relative velocity, until they were very close. From there, gravity played its role to hold them together.

Had these lobes touched with a higher relative velocity, they would have either become smushed together to form just a single lobe, or, more likely, smashed each other apart.

(With inputs from agencies)