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Close-Up Views of NASA\u2019s DART Impact to Inform Planetary Defense<\/h1>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n![\"Two](\"https:\/\/assets.science.nasa.gov\/dynamicimage\/assets\/science\/missions\/dart\/licia_cube_side_by_side.png?w=1920&h=1080&fit=clip&crop=faces%2Cfocalpoint\")
<\/a><\/figure>\nPhotos taken by the Italian LICIACube, short for the LICIA CubeSat for Imaging of Asteroids. These offer the closest, most detailed observations of NASA\u2019s DART (Double Asteroid Redirection Test) impact aftermath to date. The photo on the left was taken roughly 2 minutes and 40 seconds after impact, as the satellite flew past the Didymos system. The photo on the right was taken 20 seconds later, as LICIACube was leaving the scene. The larger body, near the top of each image is Didymos. The smaller body in the lower half of each image is Dimorphos, enveloped by the cloud of rocky debris created by DART\u2019s impact.<\/div>\nNASA\/ASI\/University of Maryland<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\nOn Sept. 11, 2022, engineers at a flight control center in Turin, Italy, sent a radio signal into deep space. Its destination was NASA\u2019s DART (Double Asteroid Redirection Test) spacecraft flying toward an asteroid more than 5 million miles away.
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The message prompted the spacecraft to execute a series of pre-programmed commands that caused a small, shoebox-sized satellite contributed by the Italian Space Agency (ASI)<\/a>, called LICIACube, to detach from DART.
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Fifteen days later, when DART\u2019s journey ended in an intentional head-on collision with near-Earth asteroid Dimorphos, LICIACube flew past the asteroid to snap a series of photos, providing researchers with the only on-site observations of the world\u2019s first demonstration of an asteroid deflection.
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After analyzing LICIACube\u2019s images, NASA and ASI scientists report on Aug. 21 in the Planetary Science Journal <\/a>that an estimated 35.3 million pounds (16 million kilograms) of dust and rocks spewed from the asteroid as a result of the crash, refining previous estimates that were based on data from ground and space-based observations.
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While the debris shed from the asteroid amounted to less than 0.5% of its total mass, it was still 30,000 times greater than the mass of the spacecraft. The impact of the debris on Dimorphos\u2019 trajectory was dramatic: shortly after the collision, the DART team determined that the flying rubble gave Dimorphos a shove several times stronger than the hit from the spacecraft itself.
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\u201cThe plume of material released from the asteroid was like a short burst from a rocket engine,\u201d said Ramin Lolachi, a research scientist who led the study from NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland.
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The important takeaway from the DART mission is that a small, lightweight spacecraft can dramatically alter the path of an asteroid of similar size and composition to Dimorphos, which is a \u201crubble-pile\u201d asteroid \u2014 or a loose, porous collection of rocky material bound together weakly by gravity.
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\u201cWe expect that a lot of near-Earth asteroids have a similar structure to Dimorphos,\u201d said Dave Glenar, a planetary scientist at the University of Maryland, Baltimore County, who participated in the study. \u201cSo, this extra push from the debris plume is critical to consider when building future spacecraft to deflect asteroids from Earth.\u201d<\/p>\n\n\n\n![\"Bright](\"https:\/\/assets.science.nasa.gov\/dynamicimage\/assets\/science\/missions\/dart\/didymos-ejecta-trail-hubble.jpeg?w=1860&h=1257&fit=clip&crop=faces%2Cfocalpoint\")
<\/a><\/figure>\nThe tail of material that formed behind Dimorphos was prominent almost 12 days after the DART impact, giving the asteroid a comet-like appearance, as seen in this image captured by NASA\u2019s Hubble Space Telescope in October 2022. Hubble\u2019s observations were made from roughly 6.8 million miles away.<\/div>\nNASA, ESA, STScI, Jian-Yang Li (PSI); Image Processing: Joseph DePasquale<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\nDART\u2019s Star Witness<\/strong><\/h3>\nNASA chose Dimorphos, which poses no threat to Earth, as the mission target due to its relationship with another, larger asteroid named Didymos. Dimorphos orbits Didymos in a binary asteroid system, much like the Moon orbits Earth. Critically, the pair\u2019s position relative to Earth allowed astronomers to measure the duration of the moonlet\u2019s orbit before and after the collision.
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Ground and space-based observations revealed that DART shortened Dimorphos\u2019 orbit by 33 minutes. But these long-range observations, made from 6.8 million miles (10.9 million kilometers) away, were too distant to support a detailed study of the impact debris. That was LICIACube\u2019s job.<\/p>\n
After DART\u2019s impact, LICIACube had just 60 seconds to make its most critical observations. Barreling past the asteroid at 15,000 miles (21,140 kilometers) per hour, the spacecraft took a snapshot of the debris roughly once every three seconds. Its closest image was taken just 53 miles (85.3 km) from Dimorphos\u2019 surface.
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The short distance between LICIACube and Dimorphos provided a unique advantage, allowing the cubesat to capture detailed images of the dusty debris from multiple angles.
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The research team studied a series of 18 LICIAcube images. The first images in the sequence showed LICIACube\u2019s head-on approach. From this angle, the plume was brightly illuminated by direct sunlight. As the spacecraft glided past the asteroid, its camera pivoted to keep the plume in view.<\/p>\n
\n\n\n![\"Two](\"https:\/\/assets.science.nasa.gov\/content\/dam\/science\/missions\/dart\/liciacube_image_sequence.gif?w=1920&h=1080&fit=clip&crop=faces%2Cfocalpoint\")
<\/a><\/figure>\nThis animated series of images was taken by a camera aboard LICIACube 2 to 3 minutes after DART crashed into Dimorphos. As LICIACube made its way past the binary pair of asteroids Didymos, the larger one on top, and Dimorphos, the object at the bottom. The satellite\u2019s viewing angle changed rapidly during its flyby of Dimorphos, allowing scientists o get a comprehensive view of the impact plume from a series of angles.<\/div>\nASI\/University of Maryland\/Tony Farnham\/Nathan Marder<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\n\u00a0As LICIACube looked back at the asteroid, sunlight filtered through the dense cloud of debris, and the plume\u2019s brightness faded. This suggested the plume was made of mostly large particles \u2014 about a millimeter or more across \u2014 which reflect less light than tiny dust grains.<\/p>\n
Since the innermost parts of the plume were so thick with debris that they were completely opaque, the scientists used models to estimate the number of particles that were hidden from view. Data from other rubble-pile asteroids, including pieces of Bennu delivered to Earth in 2023 by NASA\u2019s OSIRIS-REx<\/a> spacecraft, and laboratory experiments helped refine the estimate.
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\u201cWe estimated that this hidden material accounted for almost 45% of the plume\u2019s total mass,\u201d said Timothy Stubbs, a planetary scientist at NASA Goddard who was involved with the study.
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While DART showed that a high-speed collision with a spacecraft can change an asteroid\u2019s trajectory, Stubbs and his colleagues note that different asteroid types, such as those made of stronger, more tightly packed material, might respond differently to a DART-like impact. \u201cEvery time we interact with an asteroid, we find something that surprises us, so there\u2019s a lot more work to do,\u201d said Stubbs. \u201cBut DART is a big step forward for planetary defense.\u201d
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The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, managed the DART mission and operated the spacecraft for NASA\u2019s Planetary Defense Coordination Office as a project of the agency\u2019s Planetary Missions Program Office.<\/em>
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By Nathan Marder, <\/strong>nathan.marder@nasa.gov<\/strong><\/a>
NASA\u2019s Goddard Space Flight Center, Greenbelt, Md.<\/strong><\/p>\n\n\n\n\n\n\nShare<\/h2>\n<\/div>\n\n
<\/a><\/figure>On Sept. 11, 2022, engineers at a flight control center in Turin, Italy, sent a radio signal into deep space. Its destination was NASA\u2019s DART (Double Asteroid Redirection Test) spacecraft flying toward an asteroid more than 5 million miles away. NASA chose Dimorphos, which poses no threat to Earth, as the mission target due to its relationship with another, larger asteroid named Didymos. Dimorphos orbits Didymos in a binary asteroid system, much like the Moon orbits Earth. Critically, the pair\u2019s position relative to Earth allowed astronomers to measure the duration of the moonlet\u2019s orbit before and after the collision. After DART\u2019s impact, LICIACube had just 60 seconds to make its most critical observations. Barreling past the asteroid at 15,000 miles (21,140 kilometers) per hour, the spacecraft took a snapshot of the debris roughly once every three seconds. Its closest image was taken just 53 miles (85.3 km) from Dimorphos\u2019 surface. \u00a0As LICIACube looked back at the asteroid, sunlight filtered through the dense cloud of debris, and the plume\u2019s brightness faded. This suggested the plume was made of mostly large particles \u2014 about a millimeter or more across \u2014 which reflect less light than tiny dust grains.<\/p>\n Since the innermost parts of the plume were so thick with debris that they were completely opaque, the scientists used models to estimate the number of particles that were hidden from view. Data from other rubble-pile asteroids, including pieces of Bennu delivered to Earth in 2023 by NASA\u2019s OSIRIS-REx<\/a> spacecraft, and laboratory experiments helped refine the estimate.
\u00a0
The message prompted the spacecraft to execute a series of pre-programmed commands that caused a small, shoebox-sized satellite contributed by the Italian Space Agency (ASI)<\/a>, called LICIACube, to detach from DART.
\u00a0
Fifteen days later, when DART\u2019s journey ended in an intentional head-on collision with near-Earth asteroid Dimorphos, LICIACube flew past the asteroid to snap a series of photos, providing researchers with the only on-site observations of the world\u2019s first demonstration of an asteroid deflection.
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After analyzing LICIACube\u2019s images, NASA and ASI scientists report on Aug. 21 in the Planetary Science Journal <\/a>that an estimated 35.3 million pounds (16 million kilograms) of dust and rocks spewed from the asteroid as a result of the crash, refining previous estimates that were based on data from ground and space-based observations.
\u00a0
While the debris shed from the asteroid amounted to less than 0.5% of its total mass, it was still 30,000 times greater than the mass of the spacecraft. The impact of the debris on Dimorphos\u2019 trajectory was dramatic: shortly after the collision, the DART team determined that the flying rubble gave Dimorphos a shove several times stronger than the hit from the spacecraft itself.
\u00a0
\u201cThe plume of material released from the asteroid was like a short burst from a rocket engine,\u201d said Ramin Lolachi, a research scientist who led the study from NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland.
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The important takeaway from the DART mission is that a small, lightweight spacecraft can dramatically alter the path of an asteroid of similar size and composition to Dimorphos, which is a \u201crubble-pile\u201d asteroid \u2014 or a loose, porous collection of rocky material bound together weakly by gravity.
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\u201cWe expect that a lot of near-Earth asteroids have a similar structure to Dimorphos,\u201d said Dave Glenar, a planetary scientist at the University of Maryland, Baltimore County, who participated in the study. \u201cSo, this extra push from the debris plume is critical to consider when building future spacecraft to deflect asteroids from Earth.\u201d<\/p>\n<\/a><\/figure>DART\u2019s Star Witness<\/strong><\/h3>\n
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Ground and space-based observations revealed that DART shortened Dimorphos\u2019 orbit by 33 minutes. But these long-range observations, made from 6.8 million miles (10.9 million kilometers) away, were too distant to support a detailed study of the impact debris. That was LICIACube\u2019s job.<\/p>\n
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The short distance between LICIACube and Dimorphos provided a unique advantage, allowing the cubesat to capture detailed images of the dusty debris from multiple angles.
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The research team studied a series of 18 LICIAcube images. The first images in the sequence showed LICIACube\u2019s head-on approach. From this angle, the plume was brightly illuminated by direct sunlight. As the spacecraft glided past the asteroid, its camera pivoted to keep the plume in view.<\/p>\n<\/a><\/figure>
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\u201cWe estimated that this hidden material accounted for almost 45% of the plume\u2019s total mass,\u201d said Timothy Stubbs, a planetary scientist at NASA Goddard who was involved with the study.
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While DART showed that a high-speed collision with a spacecraft can change an asteroid\u2019s trajectory, Stubbs and his colleagues note that different asteroid types, such as those made of stronger, more tightly packed material, might respond differently to a DART-like impact. \u201cEvery time we interact with an asteroid, we find something that surprises us, so there\u2019s a lot more work to do,\u201d said Stubbs. \u201cBut DART is a big step forward for planetary defense.\u201d
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The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, managed the DART mission and operated the spacecraft for NASA\u2019s Planetary Defense Coordination Office as a project of the agency\u2019s Planetary Missions Program Office.<\/em>
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By Nathan Marder, <\/strong>nathan.marder@nasa.gov<\/strong><\/a>
NASA\u2019s Goddard Space Flight Center, Greenbelt, Md.<\/strong><\/p>\nShare<\/h2>\n<\/div>\n