Scientists have used images collected by NASA’s DART asteroid impact mission to paint a more detailed picture of its asteroid targets Didymos and Dimorphos. The research could help better understand the formation and evolution of binary asteroids like these.
DART, which stands for “double asteroid redirection test,” has only affected the smaller body in this binary binary system, the moon Dimorphos, which orbits the larger space rock Didymos. Still, the goal was to see what impact a similar impact would have on the two organs. The data collected during this successful mission could help scientists better plan a planetary defense mission to deflect an asteroid on a collision course with Earth.
Before crashing into Dimorphos on September 26, 2023, DART was able to take images of the two near-Earth asteroids. In unison with data from the Light Italian Cubesat Asteroid Imaging Mission (LICIACube), the researchers were able to determine some of the geological features and physical properties of Didymos and Dimorphos.
The team, led by Olivier Barnouin of Johns Hopkins University’s Applied Physics Laboratory, studied the surface of Didymos, the larger of the two asteroids. The researchers found that at high elevations, Didymos is rugged and contains large boulders between 33 and 525 feet (10–160 meters) long and several craters. At low altitudes, the surface of this asteroid becomes smoother, with fewer large rocks and craters.
Its smaller moon, Dimorphos, has rocks on its surface that have a wider range of sizes. While the surface of Dimorphos is mostly crater-free, it is split with several cracks or “faults”.
The findings helped Barnouen and his colleagues determine that Dimorphos likely formed from material ejected from Didymos and then accreted by gravity.
The team used the number of craters on the two asteroids to estimate the age of the two asteroids. they determined that the Didymos parent body was 12.5 million years old, between 40 and 130 times older than Dimorphos. They estimate the moon’s age to be about 0.3 million years.
Connected: NASA’s DART mission to hit an asteroid completely changed the shape of its target
By looking at the size of the stones and their distribution in Dimorphos, a separate team of scientists led by Maurizio Paiola from the INAF – Padua Astronomical Observatory found that they formed at different times and not all at once.
This suggests that the rocks on Dimorphos’ surface are directly inherited from Didymos, further supporting the idea that moons in binary asteroid systems form from material ejected from their larger partners. This process would also explain a distinctive ridge at the equator of the parent body, Didymos.
Watch
Another team of researchers, led by Naomi Murdoch of the University of Toulouse, looked at traces of stones traced across the surface of Didymos. They found that the surface of Didymos is composed of very loose material, capable of supporting much less weight than dry sand on Earth or lunar soil on the Moon.
Meanwhile, Alice Lucchetti of the INAF-Astronomical Observatory of Padua and colleagues also discovered that the rocks on the surface of Dimorphos crack over a period of about 100,000 years through a process called “thermal fatigue”, which is the result of changing temperatures causing micro- faults in the rock.
Although 100,000 years may seem like an incredibly long time to us, geologically it is a short period, especially in a solar system that is about 4.6 billion years old. This means that the thermal fatigue experienced by Dimorphos is rapid. This is the first time that rapid thermal fatigue of a rocky asteroid composed of silicate materials and nickel-iron has been observed.
A third team, led by Université de Toulouse researcher Colas Robin, compared 34 stones on the surface of Dimorphos, which ranged from 5.5 feet (1.67 meters) to 22 feet (6.7 meters) with rocks found on the loose ” piles of rubble’ asteroids Itokawa, Ryugu and Bennu.
They found similarities between the rock morphologies of all these asteroids and proposed to Robin and colleagues a common mechanism for formation and evolution.
The teams’ results build a detailed picture of the Didymos system as it was before DART impacted Dimorphos. The findings could help the European Space Agency’s (ESA) upcoming Hera mission.
Expected to launch in October this year, Hera will rendezvous with Didymos and Dimorphos in September 2026. One of Didymous’s binary system, Hera, will capture higher-resolution data, allowing for a more comprehensive study of the system. as it is after the impact of DART. This should help scientists better determine the consequences of DART’s collision with Dimorphos.
The three teams’ research papers were published Tuesday (July 30) in the journal Nature.
