by NASA’s dramatic Double Asteroid Redirection Test (DART) was a resounding success, according to scientists.
Before the ARROW spaceship on purpose fell on Dimorphos On September 26, 2022, scientists knew very little about the asteroid’s size, shape, or composition. Six months later, they now have the clearest view yet of the entire body, which is 177 meters across.
“I have a feeling it looks like a happy fish swimming to the left with its nose up,” said Carolyn Ernst, planetary scientist at Johns Hopkins University’s Applied Physics Laboratory (APL), of a new high-resolution mosaic of Dimorphos, released Monday (March 13) at the 54th Lunar and Planetary Science Conference (LPSC) being held in Texas and virtually.
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The mosaic was assembled from the last 10 images acquired by the Didymos Reconnaissance and Asteroid Camera for Optical Navigation (Draco), the camera onboard DART that captured an image of Dimorphos every second for the last four hours prior to DART’s impact.
“I knew the final images would be spectacular, and somehow they still managed to exceed my expectations,” said Nancy Chabot, planetary scientist at APL. Chabot attributed the mission’s success to the collaboration of a vast team that included scientists from 100 institutes in 28 countries worldwide.
DART’s impact shortened the time it takes for Dimorphos to orbit its larger asteroid companion Didymos by 33 minutes to 11 hours and 23 minutes. To arrive at this number, scientists studied the Didymos binary system with telescopes located on all of them seven continents.
Over 259,000 images captured by DRACO are now available online as part of NASA Planetary Data System (opens in new tab). These pictures show some of the 2.2 million pounds (1 million kilograms) Ejecta ejected by the impact of Dimorphos and show that the asteroid’s surface is covered with boulders of different sizes, helping researchers to confirm that the asteroid is an asteroid pile of rubble.
Using this data, the scientists reconstructed the final moments of DART, including the collision itself. According to Ernst, the probe’s targeted impact site was 25 inches wide (66 centimeters). That’s smaller than DART’s cross section, so the star tracker spurting out of the underside of the probe was likely the first piece to take the hit. Microseconds later, DART’s solar cells struck one of Dimorphos’ boulders, but there wouldn’t have been time for one part of the spacecraft to communicate the shock to the other, Ernst said.
Scientists also announced Monday that the names of five features on the surface of Dimorphos have been accepted by the International Astronomical Union (IAU), the agency that assigns names to celestial bodies.
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Some of the new research presented included the final moments of DART and Hubble Space Telescope observations of the ejecta and tail formations. These realizations that were published on March 1st, highlighted the mission as the first to see growing not just one, but two tails of Dimorphos. (Astronomers used to spot asteroids with tails, but they had never seen a shape.) The Hubble Space Telescope will continue observing until Didymos gets too close to the Sun to be observed safely, which will happen in early July.
Scientists also said DART created a crater ranging from 130 feet (40 m) to 196 feet (60 m) wide when it fell between two boulders — Atabaque and Bodhran — on Dimorphos.
All the drama was witnessed firsthand LICIACube (short for “Light Italian Cubesat for Imaging of Asteroids”), a 31-pound (14-kilogram) satellite, smaller than a shoebox, that two weeks before impact hitchhiked on DART and moved to a safe distance. The satellite recorded everything it saw, including the bright flash immediately after DART impacted Dimorphos.
“From a scientific point of view, it’s really a treasure trove,” said Maurizio Pajola, a planetary scientist at Italy’s National Institute for Astrophysics and part of the LICIACube science team.
For DART’s “outstanding contribution” in the space field was the mission team awarded (opens in new tab) the 2023 Nelson P. Jackson Aerospace Award from the National Space Club and Foundation in early March.
The knowledge gained so far from DART’s success is critical, but that alone is not enough to understand the mission’s implications in the broader planetary defense context, the scientists said. Applying a similar “kinetic impactor” technique to another asteroid hazard will require much more research, and ongoing studies into how the resulting ejecta will evolve and behave will play an important role, they said.
Using all of the data that will be sent home by DART and more data collected by ground-based telescopes, the scientists hope to better understand what to expect from the European Space Agency Hera spaceship reaches the Didymos-Dimorphos system in 2026.
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