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NASA’s DART asteroid smash flung 2 million pounds of rock into space

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The massive tail created by the collision of a spacecraft and an asteroid earlier this year is unlocking key information about space rocks — and how to manage any such rock that may one day threaten Earth.

NASA’s Double Asteroid Redirection Test (DART) mission slammed into a small space rock called Dimorphos in late September in preparation for the possibility humans may one day want to deflect an asteroid on a collision course with Earth. Within weeks of the impact, the DART team announced that the impact shaved 32 minutes off Dimorphos’ orbit around its larger companion, Didymos — at the high range of the team’s prelaunch estimates. Scientists are now sharing additional findings about the impact during the American Geophysical Union’s annual conference happening this week in Chicago and online

“DART has been a tremendous success,” Tom Stadtler, program scientist for the DART mission, said during a news conference held on Thursday (Dec. 15) in conjunction with the meeting. “I’ve seen these results, I know that they’re extremely cool.”

Related: Behold the 1st images of DART’s wild asteroid crash!

Many of the new results focus on the stunning, comet-like tail produced by debris from the impact. Mission scientists weren’t sure in advance just how much debris DART’s collision would create, but the impact did not disappoint.

And scientists had a front-row seat, thanks to the DART spacecraft’s Italian hitchhiker, Light Italian Cubesat for Imaging of Asteroids (LICIACube), which was equipped with two cameras and deployed 15 days before DART’s impact, allowing it to fly past Dimorphos just three minutes after impact. The tiny spacecraft’s photographs show quite a cosmic mess, with clouds of material bursting off the space rock.

“The images were indeed impressive,” Alessandro Rossi, LICIACube science team member and a scientist at the Instituto di Fisica Applicata Nella Carrara in Italy, said during the news conference. “We didn’t expect some of the features that we see.”

Scientists are still analyzing LICIACube’s data, but images captured by its two cameras can offer a sense of how large certain debris is, how fast it’s traveling, and more, Rossi said. Researchers even think they can see the debris casting a shadow on the larger asteroid Dimorphos orbits, Didymos. 

Two images captured by the LICIACube’s LUKE camera before and after its closest approach to Dimorphos just minutes after DART’s impact.  (Image credit: ASA/NASA)

The debris offers a sense of the asteroid’s structure, since an asteroid of solid rock would produce much less ejecta than an asteroid made of boulders clumped together — picture bouncing a tennis ball off pavement compared to throwing it into a sandbox.

In addition, the ejecta has solved a key mystery about Dimorphos and Didymos. Scientists suspected that the two space rocks would be made of similar material, but didn’t have a way to test that theory, either as the spacecraft sped to its destination or by using ground-based telescopes, none of which are powerful enough to see Dimorphos directly.

Before impact, scientists could use the light they saw from the system to analyze the composition of the pair of space rocks overall, knowing that almost all of that light came from Didymos. But in similar data taken just after the impact, it’s the debris flying off Dimorphos that’s responsible for most of the light.

Comparing the two light signatures showed that although some slight differences appear, the material seems to be quite similar between the two asteroids. “We’re very excited to see that these two objects are in fact similar in composition,” Cristina Thomas, a planetary scientist at Northern Arizona University who leads the DART observations working group, said during the news conference.

Scientists will be studying Dimorphos’ fresh tail for quite a while, including digging deeper into observations taken in the days following the collision, gathering new data to see how the plume changes over time, and comparing observations from different vantage points.

“We have a vision of the ejecta plume from close by, we have a vision from the ground, we have the vision from Hubble Space Telescope, from the James Webb Space Telescope,” Rossi said. “So we have a lot of different geometries to compare with, and this is allowing us to clearly characterize the ejecta plume from many points of view.”

A time-lapse view centered on Didymos shows its massive tail, with background stars appearing as streaks of light, taken on Nov. 30, 2022, about two months after DART’s impact.  (Image credit: Magdalena Ridge Observatory/NM Tech)

Crunching the numbers 

During the news conference, scientists also shared two key numbers they have calculated since the collision.

First, they’ve begun estimating how much debris flew off the asteroid: at least 2.2 million pounds (1 million kilograms), and possibly as much as 22 million pounds (10 million kg). Given Dimorphos’ total mass of perhaps 11 billion pounds (5 billion kg), the rock could have lost just 0.2% of its material, even if the higher estimate proves correct.

“We’re talking about a tiny, tiny fraction,” Andy Rivkin, a planetary scientist at the Johns Hopkins Applied Physics Laboratory and co-lead of DART, said in the news conference.

The second number goes to the core of the DART mission’s purpose. DART wasn’t about seeing inside an asteroid, it was about planetary defense. This involves hunting for asteroids on orbits that intersect with Earth’s and calculating whether the two bodies might ever find themselves in the same place at the same time. 

If scientists ever spot a sizeable asteroid that poses a real threat, the thinking goes, humans could try to intervene by speeding up the asteroid’s orbit around the sun so that it misses its appointment with Earth. DART tested one technique for that, called kinetic impact — a fancy name for hitting the asteroid with a heavy, fast-moving object.

However, scientists don’t have a good enough sense of how the characteristics of an asteroid and of a collision could interact to produce a specific change in the rock’s momentum in space, making it difficult to know what size spacecraft to launch, for example. 

Scientists use a crucial number, called the “momentum transfer factor” or beta, to describe how effective an asteroid impact is. If a spacecraft hits an asteroid head-on in a collision that doesn’t produce any debris, the space rock will pick up exactly the momentum the spacecraft had as it crashed, a beta of 1.

A host of characteristics can affect the beta factor — whether the spacecraft hits a smooth patch or a large boulder, for example, the internal structure of the asteroid, and what material the asteroid is made of — but let’s set those aside for simplicity’s sake.

Debris shooting off the asteroid and into space gives the asteroid additional momentum, gradually increasing the beta factor of the impact. And scientists have now calculated the beta factor of DART’s impact at 3.6. That value means that the asteroid picked up more than triple the momentum than it would have in a clean impact, and that the debris created by the impact affected the asteroid even more than the spacecraft itself.

“This is very good news for the kinetic impact technique,” Andy Cheng, DART investigation team lead at the Johns Hopkins Applied Physics Laboratory, said during the news conference. “At least in the case of DART, the kinetic impact on the target was really efficient at changing the orbit of the target.”

The calculation also gives scientists much-needed real-world data to understand how an asteroid’s characteristics affect momentum transfer — data that are crucial for determining just how massive a kinetic impact spacecraft should be to avert catastrophe. DART’s successor, the European Space Agency’s Hera spacecraft, currently scheduled to launch in 2024, will also play a key role here after it arrives (much more gently) at the asteroid pair to study Dimorphos and Didymos up close.

“Where we’re trying to get is to have that ability to observe an asteroid, both from the ground or maybe with a reconnaissance mission, and infer what the response will be if we do deploy a kinetic impactor against it,” Stadtler said.

Despite the intriguing findings in terms of both science and planetary defense, the mission team emphasized that they were far from done with the project.

“From here, now, we actually get to get to our dream list, where we can start to think about the really complicated dynamical effects that were predicted, that we weren’t sure that we would be able to observe because we’d never done this before,” Thomas said. “We are looking forward to more observations that are going to allow us to study things in great detail, and I think that’s a really exciting place to be.”

Email Meghan Bartels at mbartels@space.com or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.



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DART Mission: ‘Rail cars’ of material released after NASA spacecraft hit asteroid

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CNN
 — 

When NASA’s Double Asteroid Redirection Test spacecraft slammed into the tiny asteroid Dimorphos, the impact certainly left a mark.

The intentional collision, which took place on September 26 as a test of asteroid deflection technology, displaced more than 2 million pounds (1 million kilograms) of rocks and dust from the asteroid into space. Scientists estimate it was enough material to fill about six or seven rail cars.

The insights gained from the collision are helping scientists learn how this planetary defense technique might be used in the future. That’s if an asteroid is ever discovered to be on a collision course with Earth.

Neither Dimorphos, nor the larger asteroid Didymos that it orbits, pose a threat to Earth, but the system made for excellent target practice.

New findings and images from the impact were shared Thursday at the American Geophysical Union Fall Meeting in Chicago.

“What we can learn from the DART mission is all part of a NASA’s overarching work to understand asteroids and other small bodies in our Solar System,” said Tom Statler, program scientist for DART at NASA, in a statement.

“Impacting the asteroid was just the start. Now we use the observations to study what these bodies are made of and how they were formed — as well as how to defend our planet should there ever be an asteroid headed our way.”

Images captured by space and ground-based telescopes before and after the impact are helping scientists piece together what happened when the spacecraft crashed into Dimorphos at about 14,000 miles per hour (22,530 kilometers per hour).

The DART team calculated that the transfer of momentum when the spacecraft hit the asteroid was 3.6 times greater than if the asteroid had absorbed the spacecraft and no material was blasted from the surface. The momentum created when Dimorphos’ surface material blasted out into space contributed to moving the asteroid more than the spacecraft did, the researchers said.

“Momentum transfer is one of the most important things we can measure, because it is information we would need to develop an impactor mission to divert a threating asteroid,” said Andy Cheng, DART investigation team lead from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, in a statement.

“Understanding how a spacecraft impact will change an asteroid’s momentum is key to designing a mitigation strategy for a planetary defense scenario.”

The DART mission successfully changed the trajectory of the asteroid Dimorphos, marking the first time humanity intentionally changed the motion of a celestial object in space.

Prior to impact, it took Dimorphos 11 hours and 55 minutes to orbit Didymos. Now, it takes Dimorphos 11 hours and 23 minutes to circle Didymos. The DART spacecraft changed the moonlet asteroid’s orbit by 32 minutes.

Initially, astronomers expected DART to be a success if it shortened the trajectory by 10 minutes.

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DART Mission: ‘Rail cars’ of material released after NASA spacecraft hit asteroid

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CNN
 — 

When NASA’s Double Asteroid Redirection Test spacecraft slammed into the tiny asteroid Dimorphos, the impact certainly left a mark.

The intentional collision, which took place on September 26 as a test of asteroid deflection technology, displaced more than 2 million pounds (1 million kilograms) of rocks and dust from the asteroid into space. Scientists estimate it was enough material to fill about six or seven rail cars.

The insights gained from the collision are helping scientists learn how this planetary defense technique might be used in the future. That’s if an asteroid is ever discovered to be on a collision course with Earth.

Neither Dimorphos, nor the larger asteroid Didymos that it orbits, pose a threat to Earth, but the system made for excellent target practice.

New findings and images from the impact were shared Thursday at the American Geophysical Union Fall Meeting in Chicago.

“What we can learn from the DART mission is all part of a NASA’s overarching work to understand asteroids and other small bodies in our Solar System,” said Tom Statler, program scientist for DART at NASA, in a statement.

“Impacting the asteroid was just the start. Now we use the observations to study what these bodies are made of and how they were formed — as well as how to defend our planet should there ever be an asteroid headed our way.”

Images captured by space and ground-based telescopes before and after the impact are helping scientists piece together what happened when the spacecraft crashed into Dimorphos at about 14,000 miles per hour (22,530 kilometers per hour).

The DART team calculated that the transfer of momentum when the spacecraft hit the asteroid was 3.6 times greater than if the asteroid had absorbed the spacecraft and no material was blasted from the surface. The momentum created when Dimorphos’ surface material blasted out into space contributed to moving the asteroid more than the spacecraft did, the researchers said.

“Momentum transfer is one of the most important things we can measure, because it is information we would need to develop an impactor mission to divert a threating asteroid,” said Andy Cheng, DART investigation team lead from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, in a statement.

“Understanding how a spacecraft impact will change an asteroid’s momentum is key to designing a mitigation strategy for a planetary defense scenario.”

The DART mission successfully changed the trajectory of the asteroid Dimorphos, marking the first time humanity intentionally changed the motion of a celestial object in space.

Prior to impact, it took Dimorphos 11 hours and 55 minutes to orbit Didymos. Now, it takes Dimorphos 11 hours and 23 minutes to circle Didymos. The DART spacecraft changed the moonlet asteroid’s orbit by 32 minutes.

Initially, astronomers expected DART to be a success if it shortened the trajectory by 10 minutes.

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What DART scientists have learned about asteroid Didymos so far

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Smashing a spacecraft into an asteroid isn’t NASA’s usual approach to planetary science, but it was certainly an opportunity nonetheless.

NASA’s Double Asteroid Redirection Test (DART) spacecraft slammed into a small asteroid called Dimorphos on Sept. 26 to test a potential technique to protect Earth, should we find ourselves on a collision course with a large space rock. But the impact has also given planetary scientists a close, albeit fleeting, view of the smallest asteroid any spacecraft has visited to date.

“It’s been a thrill to see the data come in,” Carolyn Ernst, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory and instrument scientist for DART’s sole instrument, told Space.com. “Everybody’s been eagerly poring over them and busy working on them.”

Related: Asteroid impact: Here’s the last thing NASA’s DART spacecraft saw before it crashed

It’s still early days for learning about the asteroid itself; scientists have had DART’s data in hand for just a few weeks and will be running countless analyses before saying anything too confidently. “There’s a lot of instant observations you can make, but there’s a lot of careful things you have to put together before you go too far down any road,” Ernst said.

The 525-foot-wide (160 meters) Dimorphos orbits a larger asteroid called Didymos, which is perhaps 2,560 feet (780 m) across. Before DART’s November 2021 launch, scientists got a sense of both rocks’ shapes thanks to planetary radar, bouncing a beam of radio waves off the asteroids.

As the DART spacecraft was sailing toward its final destination, that’s about all scientists knew about the pair of rocks.

DART’s sole instrument, Didymos Reconnaissance and Asteroid Camera for Optical Navigation (DRACO), was able to change that. For much of DART’s journey, the asteroids appeared as one bright dot, but by about 10 minutes before impact, that dot began to transform into two small but unique worlds.

One characteristic of Dimorphos jumped out as soon as scientists saw DART’s final few images before impact: its rocky surface strewn with boulders, dust and everything in between. Spacecraft have seen this kind of surface before: Japan’s Hayabusa2 mission to Ryugu and NASA’s OSIRIS-REx mission to Bennu both found themselves exploring agglomerations of rock, worlds that scientists call “rubble pile” asteroids.

“Because it looks so rubbly and because of what we know of those other asteroids, I think a lot of people imagine that it is sort of a rubble pile or kind of a loosely held-together collection of rocks,” Ernst said.

NASA’s OSIRIS-REx spacecraft captured this image of the asteroid Bennu using its MapCam imager on Dec. 12, 2018. (Image credit: NASA/Goddard/University of Arizona)

That said, DART didn’t reveal the innards of Dimorphos, so the rubble pile appearance may not hold up. “We don’t have a direct way of measuring the interior,” Ernst said. “Could the interior be a bunch of larger objects with smaller stuff on top of it? Could it be what it looks like on the surface all the way down? We don’t directly have any insight into that.”

A second characteristic of Dimorphos that struck Ernst during DART’s approach was its egg-like shape, at least as seen from DART’s approach angle. “It was less irregular than I expected,” she said. “People often call asteroids big potatoes because they have plenty irregular shapes. So in that sense, I think it was more regularly shaped than I had expected.”

As analysis continues, Ernst added, scientists will be looking for clues about whether the material on Dimorphos’ surface appears to move, which could make the asteroid relatively round.

Scientists can also look forward to insight from the European Space Agency’s Hera mission, due to launch in 2024 on a SpaceX Falcon 9 rocket and arrive at Dimorphos two years later. Hera will explore the asteroid and the impact’s aftermath in three dimensions and without DART’s haste.

A glimpse at Didymos 

DART’s view of Dimorphos’ larger companion, Didymos, was even more cursory, since near the end of approach it slipped out of the spacecraft’s field of view. But planetary scientists are studying Didymos with the data DART did send home.

“We have some interesting, intriguing looks at Didymos that we will absolutely be able to do some science with,” Ernst said.

Even the passing view showed that Didymos and Dimorphos are two distinct bodies, despite their proximity. “The surface definitely looks different than Dimorphos,” Ernst said. “You can definitely see some big boulders, on the limb especially. But it does not look like a giant pile of rocks, like Dimorphos does.”

In particular, she noted that Didymos seems to show more variation in terrain between smooth and rough patches compared to Dimorphos’ seemingly uniformly rocky surface.

The differences between Didymos and Dimorphos could influence how scientists try to explain the formation of binary asteroids. One idea suggests that the main body can spin so fast that material flies off it, eventually coalescing into a moon; a second idea posits that if the asteroid strays too close to a large planet, the planet’s gravity can tear away material that becomes the moonlet.

Scientists believe about 15% of near-Earth asteroids are actually binary systems, with the occasional three-piece asteroid thrown in.

Meaning in the mess 

Thanks to the DART mission’s design, the spacecraft’s abrupt demise didn’t mark the end of data scientists can use to understand Dimorphos.

Firstly, DART carried with it a small companion called the Light Italian Cubesat for Imaging of Asteroids (LICIACube) that it deployed a couple weeks before the impact. LICIACube was equipped with two cameras and flew past the impact site about three minutes after DART arrived in hopes of spotting a crater or perhaps some debris.

“We didn’t know what they would show when they set out to do it,” Ernst said. But the LICIACube images showed rubble flying off Dimorphos in streamers. “Those images, they were quite striking and amazing.”

Such large quantities of debris suggest that Dimorphos consists of material held together relatively weakly; consider throwing a tennis ball into a sandbox compared to bouncing it off a sidewalk. But there’s a downside to the messiness of the impact as well. The LICIACube images are so full of debris that scientists can’t decipher much about the asteroid’s natural surface from the images.

But LICIACube wasn’t DART’s only witness. In addition, the mission recruited telescopes on the ground and in space to watch the aftermath of DART’s collision.

The mission’s planetary defense goal drove the primary duty of these observers. Should humans discover an asteroid that threatens to collide with Earth, planetary defense experts say, shortening the asteroid’s orbit around the sun could ensure that the two bodies no longer risk trying to be in the same place at the same time.

To that end, the telescopes focused on the goal of clocking how long it now takes Dimorphos to circle Didymos. Dimorphos’ orbit previously lasted 11 hours and 55 minutes; in the wake of the impact, that period has decreased by 32 minutes. That was on the high end of scientists’ expectations before launch. And because rubble flying off Dimorphos would have contributed to the orbital change, the large decrease underscores how much debris DART created.

But the continuing observations also tell scientists plenty about the asteroids as space rocks, as well as about what happens when asteroids collide naturally.

Usually, the Didymos system is a single bright dot to telescopes on the ground. But just two days after impact, the asteroid pair sported a long, bright comet-like tail that stretched 6,000 miles (10,000 kilometers) into space. 

The aftermath of the DART collision with the asteroid Dimorphos as seen by SOAR Telescope two days after impact. (Image credit: NOIRLab)

Like LICIACube’s images, observations of the tail suggest that DART left quite a mess. As radiation pressure from the sun pushed debris into the tail; that debris also reflected sunlight, hence the bright smudge. 

“It basically looks like a little comet, a temporary comet,” Ernst said. 

Scientists have been able to watch the tail change over the weeks following DART’s impact. The Hubble Space Telescope has been particularly important on that front, observing the asteroid 18 times since the collision and catching Dimorphos sprout a second tail, which comets occasionally do as well.

Dimorphos isn’t the first asteroid to dress up as a comet; about one in every 10,000 space rocks is an “active asteroid” with comet-like traits like a tail. Intriguingly, scientists already thought that these confusing sights might occur when a natural impact throws rubble off the asteroid’s surface.

But there’s a lot more work to do before scientists are willing to draw any grand conclusions about asteroids from their glimpses at Didymos and Dimorphos. “I think it’s honestly going to take quite a bit of time for people to kind of reconstruct everything about what that means,” Ernst said of the tail.

Email Meghan Bartels at mbartels@space.com or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.



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Results of DART Planetary Defense Test & Stunning New Webb Image

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The results of

And more new imagery from the Webb Space Telescope … a few of the stories to tell you about – This Week at NASA!

Data Confirms DART Impact Changed Asteroid’s Motion

Data from the intentional impact of NASA’s DART spacecraft with asteroid Dimorphos confirm that …

“DART successfully changed the targeted asteroid’s trajectory.” — Bill Nelson, NASA Administrator

In fact, this first-ever planetary defense test altered Dimorphos’ orbit around a larger asteroid by 32 minutes, which far exceeded expectations.

The SpaceX Dragon Freedom crew ship carrying four astronauts splashes down in the Atlantic Ocean off the coast of Florida. Credit: NASA/Bill Ingalls

NASA’s

NASA’s SpaceX Crew-4 mission safely returned from the International Space Station after nearly six months of conducting research and technology demonstrations to prepare for human exploration beyond low-Earth orbit and to benefit life on Earth.

The two stars in Wolf-Rayet 140 produce shells of dust every eight years that look like rings, as seen in this image from NASA’s James Webb Space Telescope. Each ring was created when the stars came close together and their stellar winds collided, compressing the gas and forming dust. Credit: NASA, ESA, CSA, STScI, JPL-Caltech

Webb Sees Star Duo’s “Fingerprint”

A new Webb Space Telescope image shows a series of dust rings from a pair of stars. The stars’ orbits bring them together about once every eight years. So, like the rings of a tree trunk, the dust loops mark the passage of time.

NASA’s Space Launch System rocket will launch with Orion atop it from Launch Complex 39B at NASA’s modernized spaceport at Kennedy Space Center in Florida. Credit: NASA

New Target Date for Next Artemis I Launch Attempt

The next launch attempt of NASA’s Artemis I Moon mission is now targeted for November 14. The uncrewed flight test of our Space Launch System rocket and Orion spacecraft will thoroughly test all systems before making Artemis flights with astronauts.

That’s what’s up this week @NASA …



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Success! NASA’s DART Redirects Asteroid in ‘Watershed Moment for Humanity’

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NASA has succeeded in changing the orbit of asteroid Dimorphos. NASA crashed its Double Asteroid Redirection Test spacecraft, aka DART, into Dimorphos a few weeks ago to test one possible method of protecting Earth from a dangerous body on a collision course with our planet. 

“This is a watershed moment for planetary defense and a watershed moment for humanity,” NASA administrator Bill Nelson said while confirming the asteroid redirect during a press conference Tuesday. 

To be clear, this was only a test of one potential defense method, called “deflection by kinetic impactor,” that doesn’t require nuclear weapons or celebrities on a suicide mission a la popular Hollywood movies like 1998’s Armageddon. Dimorphos, which is actually a moonlet orbiting the larger asteroid Didymos, doesn’t pose an actual threat to Earth. In fact, no known asteroids or near-Earth objects are considered to be a threat to humanity, but there are still plenty of space rocks and comets out there yet to be discovered or tracked by astronomers. 


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DART’s impact with Dimorphos on Sept. 26 appears to have reduced the time it takes the moonlet to orbit Didymos by 32 minutes, from 11 hours and 55 minutes to 11 hours and 23 minutes, with a margin of uncertainty of about two minutes. NASA had hoped DART would alter the orbital period by at least 73 seconds but expected it could alter the orbit by at least a few minutes and perhaps tens of minutes. So the result is on the high side of the expected possibilities. 

“It looks like the recoil from the ejecta blasted off the surface was a substantial contributor to the overall push given to the asteroid, in addition to the push of the spacecraft directly impacting,” said Tom Statler, DART program scientist at NASA headquarters.

Ejecta is a technical term for the dust and debris thrown off into space as a result of the impact. Numerous images taken in the days that followed the impact by telescopes in space and on Earth showed that the ejecta was forming a tail trailing Dimorphos similar to what we see with comets orbiting the sun. 

Nancy Chabot, the DART coordination lead from the Johns Hopkins Applied Physics Laboratory, noted that although the result is considered a resounding success, it still represents only a 4 percent change in the asteroid’s orbital period.   

“It just gave it a small nudge, but if you wanted to do this in the future, it could potentially work but you’d want to do it years in advance. Warning time is really key.”

Chabot added that the physical location of Dimorphos also changed ever so slightly and the space stone now orbits Didymos a little more tightly than before the impact.   

Scientists on the DART team are continuing to acquire more data from observatories around the world to better understand the dynamics of the impact and its effects. 

Later in the decade, the European Space Agency’s Hera project aims to send another spacecraft to conduct detailed surveys of Dimorphos and Didymos, including studying the impact crater left by DART. 

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DART mission successfully changed motion of an asteroid

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CNN
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The Double Asteroid Redirection Test successfully changed the trajectory of the asteroid Dimorphos when the NASA spacecraft intentionally slammed into the space rock on September 26, according to the agency.

The DART mission, a full-scale demonstration of deflection technology, was the world’s first conducted on behalf of planetary defense. The mission was also the first time humanity intentionally changed the motion of a celestial object in space.

Prior to impact, it took Dimorphos 11 hours and 55 minutes to orbit its larger parent asteroid Didymos. Astronomers used ground-based telescopes to measure how Dimorphos’ orbit changed after impact.

Now, it takes Dimorphos 11 hours and 23 minutes to circle Didymos. The DART spacecraft changed the moonlet asteroid’s orbit by 32 minutes.

Initially, astronomers expected DART to be a success if it shortened the trajectory by 10 minutes.

“All of us have a responsibility to protect our home planet. After all, it’s the only one we have,” said NASA Administrator Bill Nelson.

“This mission shows that NASA is trying to be ready for whatever the universe throws at us. NASA has proven we are serious as a defender of the planet. This is a watershed moment for planetary defense and all of humanity, demonstrating commitment from NASA’s exceptional team and partners from around the world.”

Neither Dimorphos nor Didymos pose a threat to Earth, but the double-asteroid system was a perfect target to test deflection technology, according to the DART team.

“For the first time ever, humanity has changed the orbit of a planetary object,” said Lori Glaze, director of the Planetary Science Division at NASA.

“As new data come in each day, astronomers will be able to better assess whether, and how, a mission like DART could be used in the future to help protect Earth from a collision with an asteroid if we ever discover one headed our way.”

The DART team continues to gather data by observing the double-asteroid system, and the orbital measurement may become more precise in the future. Currently, there is an uncertainty of plus or minus two minutes.

A new image of Dimorphos, captured by the Hubble Space Telescope, shows that the debris trail’s cometlike tail has split into two. Scientists are still working to understand the significance of the split.

The team is now focusing on measuring how much momentum was transferred from DART to Dimorphos. At the time of impact, the spacecraft was moving at about 14,000 miles per hour (22,530 kilometers per hour). Astronomers will analyze the amount of rocks and dust blasted into space after impact.

The DART team believes that the recoil from the plume “substantially enhanced” the spacecraft’s push against the asteroid, not unlike the release of air from a balloon propels it in the opposite direction, according to NASA.

“Although we have done more to the system than simply change the orbit, we may have left Dimorphos wobbling a bit,” said Tom Statler, DART program scientist at NASA. “So over time, there may be some interaction between the wobble and the orbit and things will adjust. But it’s certainly never going to go back to the old 11 hour 55 minute orbit.”

Astronomers are still investigating the surface of Dimorphos and how weak or strong it is. The DART team’s first look at Dimorphos, provided by DART before the crash, suggests that the asteroid is a pile of rubble held together by gravity.

Imagery continues to return from the Light Italian CubeSat for Imaging of Asteroids, or LICIACube, the mini satellite provided by the Italian Space Agency that tagged along as a robotic photojournalist on DART’s mission.

In about four years, the European Space Agency’s Hera mission will also fly by the double-asteroid system to study the crater left by the collision and measure the mass of Dimorphos.

“DART has given us some fascinating data about both asteroid properties and the effectiveness of a kinetic impactor as a planetary defense technology,” said Nancy Chabot, the DART coordination lead from the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. “The DART team is continuing to work on this rich dataset to fully understand this first planetary defense test of asteroid deflection.”

The research team chose Dimorphos for this mission because its size is comparable to asteroids that could pose a threat to Earth. An asteroid the size of Dimorphos could cause “regional devastation” if it hit Earth.

Near-Earth objects are asteroids and comets with an orbit that places them within 30 million miles (48.3 million kilometers) from Earth. Detecting the threat of near-Earth objects that could cause grave harm is a primary focus of NASA and other space organizations around the world.

No asteroids are currently on a direct impact course with Earth, but more than 27,000 near-Earth asteroids exist in all shapes and sizes.

Finding populations of hazardous asteroids and determining their sizes are priorities of NASA and its international partners. The design for a space-based telescope called the Near-Earth Object Surveyor mission is currently in review.

“We should not be too eager to say that one test on one asteroid tells us exactly how every other asteroid would behave in a similar situation,” Statler said. “But what we can do is use this test as an anchor point for our physics calculations in our simulations that tell us how different kinds of impacts in different situations should behave.”

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Post-impact images of DART mission have not disappointed

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Enlarge / Nailed the landing.

At a press conference shortly before NASA’s Double Asteroid Redirection Test (DART) spacecraft smashed into an asteroid, a reporter tried to get a sense of just what would happen as a bunch of metal and electronics smashed into a pile of rubble left over from the birth of the Solar System. “Give us a sense of this combat between our spacecraft and this rock,” the reporter asked a scientist at the Applied Physics Lab.

“The spacecraft’s going to lose,” APL’s Nancy Chabot quipped back.

The amazing thing about that loss is that we got to experience it in real time, as the last image from DART’s onboard camera cut out after only a small fraction of it was transmitted to Earth.

  • One of the last images taken that captures both objects in the Didymos system: Didymos and its smaller companion Dimorphos, the latter being DART’s target

  • As DART approached, Dimorphos gradually filled the field of view of its camera.

  • The final image taken and transmitted by DART prior to its scheduled catastrophic disassembly.

  • The one that didn’t quite make it, as transmission of the image data was disrupted by the destruction of all transmitting hardware.

Details of the spacecraft’s crash landing/impact on the asteroid Dimorphos had to be captured on cameras that were quite a bit further from the point of impact. Many of those have now been made available, so we put together a collection of them and describe a bit about what you can see.

The closest cameras we had were on board LICIACube, a cubesat that was carried to space on board DART, and then separated a few weeks before impact. LICIACube had two onboard cameras (named Luke and Leia), one that does wide-field imaging, and one that can focus on details better. The Italian Space Agency, which ran the LICIACube mission, hasn’t indicated which camera produced which picture, but it released a number of them, including a distant view of the collision, close-ups taken shortly after, and an animation showing the sudden brightening after the collision scattered material into space.

Enlarge / A close-up and somewhat overexposed view of the impact, showing lots of material in the vicinity of Dimorphos.
Enlarge / A more distant view of the collision aftermath, showing that Dimorphos looks a bit indistinct due to all the material ejected in the aftermath of the collision.

For those uncertain, the collision didn’t produce enough light on its own to be visible in these images. Instead, the debris ejected from the asteroid by DART reflected a lot more sunlight than the asteroid could on its own.

The brightening was large enough that Earth-bound telescopes also caught the brightening; in a few cases, their operators put the images online as they became available. Both of the ones I’ve found show the Didymos/Dimorphos system moving peacefully past background stars from Earth’s perspective (with most of the light reflected off the far larger Didymos). Suddenly, the object brightens significantly, with the debris gradually moving off to one side of the asteroids.

There are two big differences between the images. One image taken by the ATLAS project, which is based in Hawaii but has telescopes there, South America, and South Africa—the collision was only visible from the last of those. In its image, the asteroid is moving right to left against the background stars.

In contrast, the Las Cumbres observatory’s data from a telescope in South Africa shows the Didymos system moving across the star field in the opposite orientation. But it also has some rather significant information: time stamps for each exposure in the animation, which makes it clear that most of the action took place over roughly a half hour.

The ESA has also produced a video of the collision that covers the same time period, and posted it online.



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NASA’s DART asteroid impact test left a trail over 6,000 miles long

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NASA’s successful asteroid impact test created a beautiful mess, apparently. As the Associated Press reports, astronomers using the Southern Astrophysical Research (SOAR) Telescope in Chile have captured an image revealing that DART’s collision with Dimorphos left a trail of dust and other debris measuring over 6,000 miles long. The spacecraft wasn’t solely responsible — rather, the Sun’s radiation pressure pushed the material away like it would with a comet’s tail.

The trail is only likely to get larger, according to the researchers. It should eventually stretch to the point where the dust stream is virtually unrecognizable from the usual particles floating in the Solar System. NASA didn’t create headaches for future probes and explorers. The space agency chose Dimorphos (a moonlet of the asteroid Didymos) as the deliberate crash wouldn’t pose a threat to Earth.

The capture was about more than obtaining a dramatic snapshot, of course. Scientists will use data collected using SOAR, the Astronomical Event Observatory Network and other observers to understand more about the collision and Dimorphos itself. They’ll determine the amount and speed of material ejected from the asteroid, and whether or not DART produced large debris chunks or ‘merely’ fine dust. Those will help understand how spacecraft can alter an asteroid’s orbit, and potentially improve Earth’s defenses against wayward cosmic rocks.

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Immense Trail of Debris From DART Collision With Asteroid Dimorphos Captured by SOAR Telescope

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Astronomers using the SOAR telescope in Chile captured the vast plume of dust and debris blasted from the surface of the asteroid Dimorphos by NASA’s DART spacecraft when it collided on September 26, 2022. In this image, the more than 10,000-kilometer-long dust trail — the ejecta that has been pushed away by the Sun’s radiation pressure, not unlike the tail of a comet — can be seen stretching from the center to the right-hand edge of the field of view. Credit: CTIO/NOIRLab/SOAR/NSF/AURA/T. Kareta (Lowell Observatory), M. Knight (US Naval Academy), Image processing: T.A. Rector (University of Alaska Anchorage/NSF’s NOIRLab), M. Zamani & D. de Martin (NSF’s NOIRLab)

SOAR Telescope Catches Dimorphos’s Expanding Comet-like Tail After DART Impact

The SOAR Telescope in Chile imaged the more than 10,000 kilometers long trail of debris blasted from the surface of Dimorphos two days after the asteroid was impacted by

“It is amazing how clearly we were able to capture the structure and extent of the aftermath in the days following the impact.” — Teddy Kareta

Two days after DART’s collision, astronomers Teddy Kareta (Lowell Observatory) and Matthew Knight (US Naval Academy) captured the vast plume of dust and debris blasted from the asteroid’s surface with the 4.1-meter Southern Astrophysical Research (SOAR) Telescope,[1] at NSF’s NOIRLab’s Cerro Tololo Inter-American Observatory in Chile. In this new image, the dust trail — the ejecta that has been pushed away by the Sun’s radiation pressure, similar to the tail of a comet — can be seen stretching from the center to the right-hand edge of the field of view, which is about 3.1 arcminutes at SOAR using the Goodman High Throughput Spectrograph. At Didymos’s distance from Earth at the time of the observation, that would translate to at least 6,000 miles (10,000 kilometers) from the point of impact.

An artist’s representation of NASA’s DART spacecraft flying toward the twin asteroids, Didymos and Dimorphos. The larger asteroid, Didymos, was discovered by the University of Arizona’s Spacewatch in 1996. Credit: NASA/Johns Hopkins University Applied Physics Laboratory

“It is amazing how clearly we were able to capture the structure and extent of the aftermath in the days following the impact,” said Kareta.

“Now begins the next phase of work for the DART team as they analyze their data and observations by our team and other observers around the world who shared in studying this exciting event,” said Knight. We plan to use SOAR to monitor the ejecta in the coming weeks and months. The combination of SOAR and AEON[2] is just what we need for efficient follow-up of evolving events like this one.”

These observations will allow researchers to gain knowledge about the nature of the surface of Dimorphos. They will be able to gauge how much material was ejected by the collision, how fast it was ejected, and the distribution of particle sizes in the expanding dust cloud. For example, the observations will reveal whether the impact caused the moonlet to throw off big chunks of material or mostly fine dust. Analyzing this data will help astronomers protect Earth and its inhabitants by better understanding the amount and nature of the ejecta resulting from an impact, and how that might alter an asteroid’s orbit.

SOAR’s observations demonstrate the capabilities of NSF-funded AURA facilities in planetary-defense planning and initiatives. In the future, Vera C. Rubin Observatory, funded by NSF and the US Department of Energy and currently under construction in Chile, will conduct a census of the Solar System to search for potentially hazardous objects. 

Didymos was discovered in 1996 with the University of Arizona 0.9-meter Spacewatch Telescope located at Kitt Peak National Observatory, a Program of NSF’s NOIRLab.

Notes

  1. SOAR is designed to produce the best quality images of any observatory in its class. Located on Cerro Pachón, SOAR is a joint project of the Ministério da Ciência, Tecnologia e Inovações do Brasil (MCTI/LNA), NSF’s NOIRLab, the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).
  2. The Astronomical Event Observatory Network (AEON) is a facility ecosystem for accessible and efficient follow-up of astronomical transients and Time Domain science. At the heart of the network, NOIRLab, with its SOAR 4.1-meter and Gemini 8-meter telescopes (and soon the Víctor M. Blanco 4-meter Telescope at CTIO), has joined forces with Las Cumbres Observatory to build such a network for the era of Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST). SOAR is the pathfinder facility for incorporating the 4-meter-class and 8-meter-class telescopes into AEON.

More information

NSF’s NOIRLab, the US center for ground-based optical-infrared astronomy, operates the international Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and Vera C. Rubin Observatory (operated in cooperation with the Department of Energy’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on Iolkam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O’odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.



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