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A Powerful Recoil Effect Magnified NASA’s Asteroid Deflection Experiment

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Composite image of the Didymos-Dimorphos system taken on November 30, showing its new ejecta tail.

Scientists continue to pore over the results of NASA’s stunningly successful DART test to deflect a harmless asteroid. As the latest findings suggest, the recoil created by the blast of debris spewing out from Dimorphos after impact was significant, further boosting the spacecraft’s influence on the asteroid.

NASA’s fridge-sized spacecraft smashed into the 535-foot-long (163-meter) Dimorphos on September 26, shortening its orbit around its larger partner, Didymos, by a whopping 33 minutes. That equates to several dozen feet, demonstrating the feasibility of using kinetic impactors as a means to deflect threatening asteroids.

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A stunning side-effect of the test were the gigantic and complex plumes that emanated from the asteroid after impact. The Didymos-Dimorphos system, located 7 million miles (11 million kilometers) from Earth, even sprouted a long tail in the wake of the experiment. DART, short for Double Asteroid Redirection Test, had a profound impact on Dimorphos, kicking up a surprising amount of debris, or “ejecta,” in the parlance of planetary scientists.

Dimorphos, as we learned, is a rubble pile asteroid, as opposed to it being a dense, tightly packed rocky body. This undoubtedly contributed to the excessive amount of ejected debris, but scientists weren’t entirely sure how much debris the asteroid shed as a result of the impact. Preliminary findings presented on Thursday at the American Geophysical Union’s Fall Meeting in Chicago are casting new light on this and other aspects of the DART mission.

Not only did DART kick up tons of ejecta, it also triggered a recoil effect that further served to nudge the asteroid in the desired direction, as Andy Rivkin, DART investigation team lead, explained at the meeting. “We got a lot of bang for the buck,” he told BBC News.

Indeed, had Dimorphos been a more compact body, the same level of recoil likely wouldn’t have happened. “If you blast material off the target then you have a recoil force,” explained DART mission scientist Andy Cheng from the Johns Hopkins University Applied Physics Lab, who also spoke at the meeting. The resulting recoil is analogous to letting go of a balloon; as the air rushes out, it pushes the balloon in the opposite direction. In the case of Dimorphos, the stream of ejecta served as the air coming out of the balloon, which likewise pushed the asteroid in the opposite direction.

Planetary scientists are starting to get a sense as to how much debris got displaced. DART, traveling at 14,000 miles per hour (22,500 km/hour), struck with enough force to spill over 2 million pounds of material into the void. That’s enough to fill around six or seven rail cars, NASA said in a statement. That estimate might actually be on the low side, and the true figure could possibly be 10 times higher, Rivkin said at the meeting.

The scientists assigned DART’s momentum factor, known as “beta,” a value of 3.6, meaning that the momentum transferred into Dimorphos was 3.6 times greater than an impact event that produced no ejecta plume. “The result of that recoil force is that you put more momentum into the target, and you end up with a bigger deflection,” Cheng told reporters. “If you’re trying to save the Earth, this makes a big difference.”

That’s a good point, as those values will dictate the parameters for an actual mission to deflect a legitimately dangerous asteroid. Cheng and his colleagues will now use these results to infer the beta values of other asteroids, a task that will require a deeper understanding of an object’s density, composition, porosity, and other parameters. The scientists are also hoping to figure out the degree to which DART’s initial hit moved the asteroid and how much of its movement happened on account of the recoil.

The speakers also produced another figure—the length of the tail, or ejecta plume, that formed in the wake of the impact. According to Rivkin, Dimorophos sprouted a tail measuring 18,600 miles (30,000 km) long.

“Impacting the asteroid was just the start,” Tom Statler, the program scientist for DART and a presenter at the meeting, said in the statement. “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.”

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Science

A Powerful Recoil Effect Magnified NASA’s Asteroid Deflection Experiment

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Composite image of the Didymos-Dimorphos system taken on November 30, showing its new ejecta tail.
Image: Magdalena Ridge Observatory/NM Tech

Scientists continue to pore over the results of NASA’s stunningly successful DART test to deflect a harmless asteroid. As the latest findings suggest, the recoil created by the blast of debris spewing out from Dimorphos after impact was significant, further boosting the spacecraft’s influence on the asteroid.

NASA’s fridge-sized spacecraft smashed into the 535-foot-long (163-meter) Dimorphos on September 26, shortening its orbit around its larger partner, Didymos, by a whopping 33 minutes. That equates to several dozen feet, demonstrating the feasibility of using kinetic impactors as a means to deflect threatening asteroids.

A stunning side-effect of the test were the gigantic and complex plumes that emanated from the asteroid after impact. The Didymos-Dimorphos system, located 7 million miles (11 million kilometers) from Earth, even sprouted a long tail in the wake of the experiment. DART, short for Double Asteroid Redirection Test, had a profound impact on Dimorphos, kicking up a surprising amount of debris, or “ejecta,” in the parlance of planetary scientists.

Animated image showing changes to the Didymos-Dimorphos system in the first month following DART’s impact.
Gif: University of Canterbury Ōtehīwai Mt. John Observatory/UCNZ

Dimorphos, as we learned, is a rubble pile asteroid, as opposed to it being a dense, tightly packed rocky body. This undoubtedly contributed to the excessive amount of ejected debris, but scientists weren’t entirely sure how much debris the asteroid shed as a result of the impact. Preliminary findings presented on Thursday at the American Geophysical Union’s Fall Meeting in Chicago are casting new light on this and other aspects of the DART mission.

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Not only did DART kick up tons of ejecta, it also triggered a recoil effect that further served to nudge the asteroid in the desired direction, as Andy Rivkin, DART investigation team lead, explained at the meeting. “We got a lot of bang for the buck,” he told BBC News.

Indeed, had Dimorphos been a more compact body, the same level of recoil likely wouldn’t have happened. “If you blast material off the target then you have a recoil force,” explained DART mission scientist Andy Cheng from the Johns Hopkins University Applied Physics Lab, who also spoke at the meeting. The resulting recoil is analogous to letting go of a balloon; as the air rushes out, it pushes the balloon in the opposite direction. In the case of Dimorphos, the stream of ejecta served as the air coming out of the balloon, which likewise pushed the asteroid in the opposite direction.

Planetary scientists are starting to get a sense as to how much debris got displaced. DART, traveling at 14,000 miles per hour (22,500 km/hour), struck with enough force to spill over 2 million pounds of material into the void. That’s enough to fill around six or seven rail cars, NASA said in a statement. That estimate might actually be on the low side, and the true figure could possibly be 10 times higher, Rivkin said at the meeting.

The scientists assigned DART’s momentum factor, known as “beta,” a value of 3.6, meaning that the momentum transferred into Dimorphos was 3.6 times greater than an impact event that produced no ejecta plume. “The result of that recoil force is that you put more momentum into the target, and you end up with a bigger deflection,” Cheng told reporters. “If you’re trying to save the Earth, this makes a big difference.”

That’s a good point, as those values will dictate the parameters for an actual mission to deflect a legitimately dangerous asteroid. Cheng and his colleagues will now use these results to infer the beta values of other asteroids, a task that will require a deeper understanding of an object’s density, composition, porosity, and other parameters. The scientists are also hoping to figure out the degree to which DART’s initial hit moved the asteroid and how much of its movement happened on account of the recoil.

The speakers also produced another figure—the length of the tail, or ejecta plume, that formed in the wake of the impact. According to Rivkin, Dimorophos sprouted a tail measuring 18,600 miles (30,000 km) long.

“Impacting the asteroid was just the start,” Tom Statler, the program scientist for DART and a presenter at the meeting, said in the statement. “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.”

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China to conduct asteroid deflection test around 2025

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HELSINKI — China will aim to alter the orbit of a potentially threatening asteroid with a kinetic impactor test as part of plans for a planetary defense system.

China is drafting a planetary defense plan and will conduct technical studies and research into developing systems to counter the threats posed by near Earth asteroids, Wu Yanhua, deputy director of the China National Space Administration (CNSA), told China Central Television (CCTV). 

At the same time, CNSA will establish an early warning system and develop software to simulate operations against the near Earth objects and test and verify basic procedures.

Finally, a mission will make close up observations of a selected potentially dangerous asteroid and then impact the target to alter its orbit. 

The mission is scheduled around the end of the 14th Five-year plan period (2021-2025) or in 2026, Wu said. 

The system would help to deal with the threat of near Earth objects to humanity and make a new contribution to China in the future, according to Wu. 

Wu made the remarks at an event to mark China’s seventh national space day in Wenchang, Hainan province. April 24 marks the anniversary of the launch of China’s first satellite, Dongfanghong-1, which was sent into orbit in 1970.

In a space “white paper” released in January it was stated that China will study plans for building a near-earth object defense system, and increase the capacity of near-earth object monitoring, cataloging, early warning, and response over the 2021-2025 period.

China held its first Planetary Defense Conference in October 2021, with sessions, papers and presentations on a range of related issues.

China is not the only nor the first space agency to be developing planetary defense capabilities.

NASA launched its Double Asteroid Redirection Test (DART) in November 2021. The spacecraft will collide with Dimorphos, a minor-planet moon orbiting the near Earth asteroid Didymos, in September this year. 

The European Space Agency will send its Hera mission to Didymos and Dimorphos later in the decade to examine the after effects of the DART mission impact. 

China is also developing a combined asteroid sample-return and comet rendezvous mission. The mission, expected to launch before 2025, will target Earth’s quasi-satellite Kamoʻoalewa, deliver samples to Earth and then head for a rendezvous with main-belt comet 311P/PANSTARRS.



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Science

NASA to launch first mission to test asteroid deflection

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The probe will then spend almost a year journeying to an asteroid system more than 6.5 million miles away from Earth. The mission’s target is Dimorphos, a space rock measuring 525 feet across that orbits a much larger asteroid named Didymos, which measures around 2,500 feet across.

Neither Dimorphos nor Didymos pose a threat to the planet, according to NASA, but the system is a “perfect testing ground” for whether crashing a spacecraft into an asteroid can effectively change its motion in space.

Next fall, NASA will smash the DART spacecraft into Dimorphos at a speed of around 15,000 mph. Telescopes on Earth have been studying Didymos and its “moonlet” Dimorphos for decades, and have observed that the smaller space rock circles its larger counterpart once every 11 hours and 55 minutes, said Nancy Chabot, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory and the mission’s coordination lead.

Chabot and her colleagues want to see if the cosmic collision can alter Dimorphos’ nearly 12-hour orbit. NASA estimates that the maneuver will change the speed of the space rock’s orbit by just a fraction of a percent — a difference of only several minutes — but the shift should be detectable by ground-based telescopes.

“This isn’t going to destroy the asteroid — it’s just going to give it a small nudge,” she said earlier this month in a news briefing. “It’s actually going to deflect its path around the larger asteroid, so we’re demonstrating asteroid deflection in this double asteroid system.”

The DART probe will be destroyed in the test, but a small, Italian-built cubesat that the spacecraft will deploy more than a week before the crash will beam back photos of the impact and its aftermath.

A follow-up mission developed by the European Space Agency will conduct a more detailed investigation of the Didymos system and will assess the outcome of the DART probe’s deflection. That mission, known as Hera, is slated to launch in October 2024.

No known asteroid larger than 450 feet has a significant chance of smashing into the planet over the next 100 years, according to NASA, but the agency said only a fraction of smaller near-Earth objects have been found so far.

The agency’s Planetary Defense Coordination Office is tasked with searching for near-Earth objects that are potentially hazardous to the planet, including those that venture within 5 million miles of Earth’s orbit, and objects large enough to cause significant damage if they hit the surface.

If in the future a large space rock is found on a collision course with Earth, tests like the DART mission could help NASA respond to the threat.

“It’s very rare for an asteroid to impact the Earth,” said Lindley Johnson, a planetary defense officer at NASA Headquarters in Washington, D.C., “but it’s something we want to know about well ahead of time.”

Denise Chow is a reporter for NBC News Science focused on general science and climate change.

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Nasa makes final steps to launch asteroid deflection test | Nasa

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Nasa is in final preparations to launch the world’s first planetary defence mission. The Double Asteroid Redirection Test (Dart) is scheduled to launch on 23 November and is a joint mission with the Johns Hopkins Applied Physics Laboratory.

Dart is designed to collide with the asteroid Dimorphos and change its orbit as a test for spotting an asteroid on collision course with Earth and deflecting its path.

At 160 metres across, Dimorphos is about the size of the Great Pyramid of Giza. It is a moon to the larger asteroid Didymos and completes an orbit of its parent rock once every 11.9 hours.

In October 2022, Dart will collide with Dimorphos at a speed of 6.6 km/s. This will change the asteroid’s velocity by about 0.4 mm/s, altering its orbital period by about 10 minutes.

If imparted early enough, small changes to an Earth-heading asteroid could be enough to avoid catastrophe.

Dart is part of a larger, two-part mission called the Asteroid Impact and Deflection Assessment (Aida) mission. The second part is the European Space Agency’s Hera mission. Scheduled for launch in October 2024, Hera will study the aftermath of the collision in closeup.

Dart will be launched from Vandenberg space force base, California, on a SpaceX Falcon 9 rocket.

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NASA’s ‘Armageddon’-style asteroid deflection mission takes off in November – TechCrunch

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NASA has a launch date for that most Hollywood of missions, the Double Asteroid Redirection Test, which is basically a dry run of the movie “Armageddon.” Unlike the film, this will not involve nukes, oil rigs or Aerosmith, but instead is a practical test of our ability to change the trajectory of an asteroid in a significant and predictable way.

The DART mission, managed by the Planetary Defense Coordination Office (!), involves sending a pair of satellites out to a relatively nearby pair of asteroids, known as the Didymos binary. It’s one large-ish asteroid, approximately 780 meters across — that’s Didymos proper — and a 160-meter “moonlet” in its orbit.

As the moonlet is more typical of the type likely to threaten Earth — there being more asteroids that are that size and not easily observed — we will be testing the possibility of intercepting one by smashing into it at nearly 15,000 miles per hour. This will change the speed of the moonlet by a mere fraction of a percent, but enough that its orbit period will be affected measurably. Knowing exactly how much will help us plan any future asteroid-deflection missions — not surprisingly, there isn’t a lot of existing science on ramming your spacecraft into space rocks.

A companion spacecraft, called the Light Italian CubeSat for Imagine Asteroids, or LICIACube, just had the finishing touches put on it last week and will be launched shortly before the operation and will attempt to fly by at the very moment of impact and capture “the resultant plume of ejecta and possibly the newly-formed impact crater.”

A very exciting and interesting mission to be sure, but had to be delayed past its original launch window of this summer, and November 23 marks the first day of the new launch window. DART is scheduled to launch from Vandenberg in Southern California at 10:20 PM on that date, aboard a SpaceX Falcon 9.

With Osiris-Rex and Japan’s Hayabusa-2 missions, Earth authorities are getting pretty good at reaching out and touching asteroids. We’ll know more about the plan of attack on the Didymos binary in the run-up to launch.

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