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How DART Scientists Know the Experiment to Shove an Asteroid Actually Worked

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LICIACube image showing the plumes of debris streaming from Dimorphos shortly after the DART impact on September 26. “Each rectangle represents a different level of contrast in order to better see fine structure in the plumes,” according to the European Space Agency.
Image: ASI/NASA/APL

Earlier this week, NASA announced that its DART spacecraft successfully moved an asteroid by a few dozen feet. This raises a valid question: How the heck did scientists figure this out, given that Dimorphos is nearly 7 million miles away? Needless to say, this task required some clever astronomy and a veritable village of astronomers.

NASA’s Double Asteroid Redirection Test, or DART, shortened the amount of time it takes Dimorphos to orbit Didymos, as the spacecraft pushed the target asteroid slightly closer to its larger companion. Dimorphos’s orbital period around Didymos used to be 11 hours and 55 minutes, but it’s now 11 hours and 23 minutes—a change of 32 minutes, give or take two minutes. That represents “tens of meters” in terms of the altered distance, as Nancy Chabot, DART coordination lead at the Johns Hopkins Applied Physics Laboratory, told reporters on Tuesday.

A ‘watershed moment’

Speaking at the same press briefing, NASA administrator Bill Nelson described the successful test as a “watershed moment for humanity.” Indeed, it marks the first time that our species has purposefully changed the motion of a celestial object. Critically, it’s also the first full-scale demonstration of an asteroid deflection strategy, one that could eventually protect us from a bona fide asteroid threat.

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See more on this story: Why DART is the most important mission ever launched to space

Dimorphos doesn’t endanger Earth, but it did offer an ideal platform for testing kinetic impactor technology. The 1,340-pound DART spacecraft, following a 10-month journey to the binary asteroid system, plowed into the 525-foot-wide (160-meter) asteroid at speeds reaching 14,000 miles per hour (22,500 kilometers per hour). DART struck the asteroid with razor-like precision on September 26, but it wasn’t immediately obvious if the impact had any kind of effect.

A Hubble Space Telescope image showing the binary asteroid system shortly after the impact on September 26. The test triggered the formation of a comet-like tail composed of Sun-blown dust.
A Hubble Space Telescope image showing the binary asteroid system shortly after the impact on September 26. The test triggered the formation of a comet-like tail composed of Sun-blown dust.
Image: NASA/ESA/STScI/Hubble

That the $308 million DART test did something to the unsuspecting asteroid was immediately obvious, with both space-based and ground-based observations revealing a dramatic plume and comet-like tail in the hours and days following the impact. It took about two weeks, however, for astronomers to confirm the new orbital dynamics imposed upon the Didymos-Dimorphos system. Two separate datasets were needed for the task, one optical and the other radar, but both pointed to the same answer: 11 hours and 23 minutes.

Catching an altered eclipse

Optical data came from ground-based observatories around the world, including the Las Cumbres Observatory (LCO) telescopes in South Africa and the Southern Astrophysical Research Telescope in Chile. A limitation of optical telescopes is that, due to the distance and small size of the Didymos-Dimorphous system, the two objects are seen as a single glowing dot. The asteroids are just 0.75 miles (1.2 km) apart, with Didymos, the larger of the two, measuring just 2,560 feet (780 meters) wide.

Ground-based optical telescopes can’t distinguish between the two, but that doesn’t mean Dimorphos is invisible to these eyes. The brightness of Didymos temporarily drops by around 10% each time Dimorphos passes in front of it. It’s through these clock-work eclipses that astronomers knew Dimorphos’s orbital period prior to the test and how they’re able to determine it now. That Dimorphos passes in front of Didymos from our perspective on Earth is fortuitous, and a key reason for why this system was chosen for the DART test.

The DART team studied reductions in brightness caused by Dimorphos’s eclipses of Didymos.
The DART team studied reductions in brightness caused by Dimorphos’s eclipses of Didymos.
Image: NASA/Johns Hopkins APL/Astronomical Institute of the Academy of Sciences of the Czech Republic/Lowell Observatory/JPL/Las Cumbres Observatory/Las Campanas Observatory/European Southern Observatory Danish (1.54-m) telescope/University of Edinburgh/The Open University/Universidad Católica de la Santísima Concepción/Seoul National Observatory/Universidad de Antofagasta/Universität Hamburg/Northern Arizona University.

Optical observatories across the world performed continuous observations over hours-long timescales. “Since the [orbital] period was close to 12 hours, having telescopes in South Africa roughly six hours away from Chile meant we could capture the other times when Dimorphos went behind or in front of Didymos we couldn’t see from Chile,” Tim Lister, an astronomer with LCO, explained in a South African Astronomical Observatory press release. “This really helped nail down the new period and the amount of change caused by the DART impact.”

Detecting ‘faint radar echoes’

The radar data came from NASA JPL’s Goldstone planetary radar in California and the NSF’s Green Bank Observatory in West Virginia. Unlike optical telescopes, radar “can get distinct signals from both objects directly,” said Chabot.

Radar imagery from the two observatories, taken each night during a two-week campaign, were combined to create before-and-after views of the binary asteroid system. This allowed astronomers to measure the “difference between where Dimorphos is observed compared to where it would have been with the original orbit,” as NASA explained in its press package.

In this radar image, the green circle shows the location of Dimorphos around the larger Didymos asteroid, seen as the bright line across the middle of the images. The blue circle shows where Dimorphos would’ve been had the DART experiment not happened.
In this radar image, the green circle shows the location of Dimorphos around the larger Didymos asteroid, seen as the bright line across the middle of the images. The blue circle shows where Dimorphos would’ve been had the DART experiment not happened.
Image: NASA/Johns Hopkins APL/JPL/NASA JPL Goldstone Planetary Radar/National Science Foundation’s Green Bank Observatory

“The Green Bank Telescope’s large collecting area makes it extremely sensitive and a prime receiving station to detect these faint radar echoes,” Jim Jackson, director of the Green Bank Observatory, explained in a statement. “These radar measurements” were key to determining “just how dramatic the event really was by sensing changes in its orbit around Didymos and definitively establishing its deflection.”

The “two independent methods” provided “the same answer,” said Chabot, in reference to Dimorphos’s new 11 hour and 23 minute orbital period. She credited the international team for getting “onto this very quickly.” But plenty of work remains.

The beginning of the beginning

Indeed, much is unknown about the effect of the experiment. DART was a rousing success, but it’s clear that scientists still have lots to learn about kinetic impactors and the art of deflecting asteroids.

For example, astronomers need to refine their estimates of Dimorphos’s mass, shape, density, and surface composition. This will help them to understand how the DART spacecraft transferred its momentum into its target and how the ensuing effects contributed to the observed orbital shift.

Dimorphos, as imaged by the DRACO instrument aboard the DART spacecraft.
Dimorphos, as imaged by the DRACO instrument aboard the DART spacecraft.
Image: NASA/Johns Hopkins APL

During Tuesday’s press briefing, Tom Statler, DART program scientist at NASA, said the recoil from the debris blasting off the surface was a major contributor to the orbital change. This is likely a consequence of Dimorphos’s physical makeup as a rubble pile asteroid, as opposed to it being a compact and cohesive rock. Statler also wondered if Dimorphos is now wobbling as a result of the impact. Astronomers are keeping a close watch on the system to refine their preliminary estimates and observe any further changes to the binary pair.

The European Space Agency is planning a follow-up mission to visit the asteroids up-close. The HERA probe, scheduled to launch in 2024, will observe Dimorphos in late 2026 and send back images and other data to help us better understand the effects of DART. A robust planetary defense system against asteroids won’t be built overnight, but this important work has now started in earnest.

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NASA’s Orion spacecraft breaks Apollo 13 flight record

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The Artemis 1 Orion crew vehicle has set a new record for a NASA flight. At approximately 8:40AM ET on Saturday, Orion flew farther than any spacecraft designed to carry human astronauts had ever before, surpassing the previous record set by Apollo 13 back in 1970. As of 10:17AM ET, Orion was approximately 249,666 miles ( from 401,798 kilometers) from Earth.

“Artemis I was designed to stress the systems of Orion and we settled on the distant retrograde orbit as a really good way to do that,” said Jim Geffre, Orion spacecraft integration manager. “It just so happened that with that really large orbit, high altitude above the moon, we were able to pass the Apollo 13 record. But what was more important though, was pushing the boundaries of exploration and sending spacecraft farther than we had ever done before.”

Of all the missions that could have broken the record, it’s fitting that Artemis 1 was the one to do it. As Space.com points out, Apollo 13’s original flight plan didn’t call for a record-setting flight. It was only after a mid-mission explosion forced NASA to plot a new return course that Apollo 13’s Odyssey command module set the previous record at 248,655 miles (400,171 kilometers) from Earth.

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With a limited oxygen supply on the Aquarius Lunar Module, NASA needed to get Apollo 13 back to Earth as quickly as possible. The agency eventually settled on a flight path that used the Moon’s gravity to slingshot Apollo 13 back to Earth. One of the NASA personnel who was critical to the safe return of astronauts Jim Lovell, Jack Swigert and Fred Haise was Arturo Campos. He wrote the emergency plan that gave the Command and Service Module enough power to make it back to Earth. Artemis 1 is carrying a “Moonikin” test dummy named after the late Arturo.

Earlier this week, Orion completed a flyby of the Moon. After the spacecraft completes half an orbit around the satellite, it will slingshot itself toward the Earth. NASA expects Orion to splash down off the coast of San Diego on December 11th.

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Shocking! This asteroid CRASHED into Earth, says NASA; Check asteroid impact site – HT Tech

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NASA has revealed that an asteroid crashed into the Earth on Saturday, November 19. Here’s where this asteroid hit Earth.

In the midst of all the terrifyingly close asteroid flybys, NASA has now revealed that an asteroid actually crashed into the Earth just days ago! NASA keeps a watch on these asteroids by studying data collected by various space and ground-based telescopes and observatories such as the Pan-STARRS, the Catalina Sky Survey and the NEOWISE telescope. However, this asteroid was seemingly missed by all of them and was discovered just hours before impact!

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NASA has revealed that the asteroid lit up the sky as it flew over Southern Ontario, Canada on Saturday, November 19. What’s shocking is that this 3-foot asteroid was detected just 3.5 hours before impact! However, such small-sized asteroids do not pose a risk to the planet.

The tech that tracked the asteroid

The asteroid was first spotted by NASA’s Catalina Sky Survey and the observations were then reported to the Minor Planet Center. NASA’s Scout impact hazard assessment system calculated the asteroid’s trajectory and possible impact sites by analyzing the data. Just minutes after getting the data, a 25 percent probability of hitting Earth’s atmosphere was calculated.

Shantanu Naidu, navigation engineer and Scout operator at JPL said in a NASA JPL blog, “Small objects such as this one can only be detected when they are very close to Earth, so if they are headed for an impact, time is of the essence to collect as many observations as possible.”

“This object was discovered early enough that the planetary defense community could provide more observations, which Scout then used to confirm the impact and predict where and when the asteroid was going to hit,” he added further.

Asteroid impact site

The possible impact sites ranged from the Atlantic Ocean off the East Coast of North America to Mexico. According to NASA, the asteroid is likely to have burned up upon entering the planet’s atmosphere and scattered small meteorites over the southern coastline of Lake Ontario.

Calculating the asteroid’s trajectory and impact site was a community effort with added inputs from amateur astronomers from the Farpoint Observatory in Eskridge, Kansas, who tracked the asteroid for more than an hour and provided the critical data required to accurately calculate the asteroid’s path and impact site.


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China plans to build nuclear-powered moon base within six years – The Province

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China plans to build its first base on the moon by 2028, ahead of landing astronauts there in subsequent years as the country steps up its challenge to NASA’s dominance in space exploration.

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The lunar base will likely be powered by nuclear energy, Caixin reported. Its basic configuration will consist of a lander, hopper, orbiter and rover, all of which would be constructed by the Chang’e 6, 7 and 8 missions.

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“Our astronauts will likely be able to go to the moon within 10 years,” Wu Weiran, chief designer of China’s lunar exploration program, said in an interview with state broadcaster CCTV earlier this week. Nuclear energy can address the lunar station’s long-term, high-power energy needs, he said.

China has ramped up its ambitions in space in recent years, sending probes to the moon, building its own space station and setting its sights on Mars. The plans have put it in direct competition with the U.S. NASA has a rover on the Red Planet and is seeking to return astronauts to the moon this decade for the first time since the Apollo program ended in the 1970s.

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Both China and the U.S. are spending billions of dollars to not just put humans on the moon, but also to access resources that could foster life on the lunar surface or send spacecraft to Mars.

In 2019, China became the first country to land a rover on the far side of the moon, and later brought back its first lunar samples. The base is intended to be the first outpost on the moon’s South Pole, an area scientists think is the best place to find water. NASA is also targeting that part of the moon. China aims to eventually expand the base into an international research station.

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