On September 26, 2022, NASA's Double Asteroid Redirect Test (DART) spacecraft impacted Dimorphos at 6.1 km/s. This first test of the kinetic impact method successfully shortened Dimorphos' orbit around Didymos by over half an hour, which was observed from Earth and by LICIACube.

Scientists are analyzing the data to understand the kinetic impact process and asteroid characteristics. DART's DRACO camera and LICIACube images are critical data sources until ESA's Hera mission, launching this October, arrives at Didymos in late 2026 for further study.

"The amount of knowledge gained out of the brief few minutes of images returned by DART and LICIACube has turned out to be extraordinary," notes Hera Principal Investigator Patrick Michel, Director of Research at CNRS at Observatoire de la Cote d'Azur, "This imagery contributed to more than 80 published scientific papers to date!"

The Nature Communications papers are a collaboration between the Johns Hopkins Applied Physics Laboratory (APL) in Maryland, USA, and several European research bodies, including Italy's National Institute for Astrophysics (INAF) and France's Institut Superieur de l'Aeronautique et de l'Espace (ISAE-Supaero).

One APL-led paper uses these inputs to model the age and origin of the two bodies: the mountain-sized Didymos is estimated to be 12.5 million years old, while Dimorphos is less than 300,000 years old, indicating recent formation or resurfacing events.

Comparing the topography and boulder distribution suggests Dimorphos was created by Didymos shedding material. Didymos, the fastest spinning asteroid visited by humankind, has rocky higher elevations and a smoother equator, from where shedding likely occurred.

Maurizio Pajola of INAF and co-authors led a paper comparing boulders on the two asteroids, concluding that Dimorphos likely formed from Didymos material, consistent with previous findings.

Surface Characteristics
Alice Lucchetti of INAF and colleagues found that thermal fatigue rapidly breaks up boulders on Dimorphos, generating fine dust faster than previously thought. This alters asteroid surface characteristics significantly.

A study led by Jeanne Bigot and Pauline Lombardo from ISAE-Supaero, supervised by Naomi Murdoch, traced boulder tracks on Didymos to reveal its low bearing capacity, much lower than dry sand or lunar soil. This finding is crucial for understanding surface responses and landing predictions.

Colas Robin and Alexia Duchene from ISAE-Supaero analyzed Dimorphos' boulders, comparing them with those on other small rubble pile asteroids like Itokawa, Ryugu, and Bennu. The similarities suggest a common formation and evolution process. The team noted that "the elongated nature of the boulders around the DART impact site implies that they were likely formed through impact processing."

2026: Dateline for Hera Arrival
Once at the Didymos system in late 2026, Hera will perform a close-up survey of Dimorphos and Didymos, releasing CubeSats for complementary observations, including the first radar survey within an asteroid. This will enhance the analysis started by DART.

Patrick Michel comments: "Hera will document fully all required characteristics of the binary system as well as the DART impact outcome. So Hera and DART together will deliver the first fully documented asteroid deflection test. This is fundamental for the validation of numerical impact models at actual asteroid scale and their application to other scenarios as well as for the assessment of the efficiency of the kinetic impactor technique."

Hera is currently completing its test campaign at ESA's ESTEC Test Centre in the Netherlands, preparing for transport to Cape Canaveral in September for an October launch by SpaceX Falcon 9.

Related Links
Hera at ESA
Asteroid and Comet Mission News, Science and Technology