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DART Showed How to Smash an Asteroid. So Where Did the Space Shrapnel Go?

DART Showed How to Smash an Asteroid. So Where Did the Space Shrapnel Go?

Nearly one year ago, NASA flung the DART spacecraft into the asteroid Dimorphos at 14,000 miles per hour. It was the first test to see whether they could slightly deflect a space rock’s trajectory using a high-speed collision, a technique that could be used to protect Earth from future killer asteroids. It worked. But now they’re trying to figure out the details of the crash. And if people have to defend earthly life from a potential asteroid impact, those details will surely matter.

Scientists are starting by studying the ejecta, boulders, and numerous smaller bits the strike cast off. They predicted there would be debris, but they didn’t know exactly what to expect. After all, compared to stars and galaxies, asteroids are tiny and dim, so it’s hard to ascertain their density and composition from afar. When you strike one, will it simply bounce? Will the probe thud into it and create a crater? Or if the asteroid is brittle, will slamming a craft into it risk creating space shrapnel that is still big enough to threaten Earth?

“This is exactly why we needed to do an in-space test of this technology. People had done laboratory experiments and models. But how would an actual asteroid, of the size we’re concerned about for planetary defense, react to a kinetic impactor?” says Nancy Chabot, the DART coordination lead and a planetary scientist at Johns Hopkins University’s Applied Physics Laboratory, which developed the craft in partnership with NASA.

Many asteroids appear to be “rubble piles,” dirt, rocks, and ice loosely held together, rather than something hard and dense like a billiard ball. The asteroid Ryugu, visited by the Japanese space agency’s Hayabusa2 in June 2018, and the asteroid Bennu, which NASA’s OSIRIS-REx took samples from in 2020, both count as rubble piles. A new study published in July in Astrophysical Journal Letters shows that Dimorphos appears to be built like that too, which means that an impact is likely to create a crater and to fling off debris on or near the asteroid’s surface.

To figure out what happened after the crash, David Jewitt, a University of California, Los Angeles astronomer, and his colleagues used the Hubble Space Telescope to zoom in repeatedly on Dimorphos. The combined deep observations allowed them to discern objects that are otherwise too faint to see. A few months after the DART probe’s impact, they found a swarm of about three dozen boulders not seen before—the largest of which is 7 meters in diameter—slowly drifting away from the asteroid. “It’s a slow-speed cloud of shrapnel from the impact that’s carrying away a significant amount of mass: about 5,000 tons in boulders. That’s quite a lot, considering the impactor itself was only half a ton. So it blew out a tremendous mass in boulders,” Jewitt says.

Other researchers, including the DART team, have also been investigating the cloud of rocks thrown off by the spacecraft’s swift punch. Chabot and her colleagues published a study in Nature earlier this year, also using Hubble photos, imaging the ejecta. They showed that at first the pieces flew off in a cone-shaped cloud, but over time, that cone turned into a tail, not so different from a comet’s tail. That finding also means that models of the behavior of comets could be applied to impactors like DART, Chabot says.

Dimorphos was never a threat to Earth, but details like these would matter in a real asteroid deflection scenario. Boulders and smaller ejecta would have to be knocked out of the way, along with the rest of the asteroid, in order to spare the planet. Or let’s say the asteroid wasn’t spotted until it was very close to Earth, and its trajectory couldn’t be altered enough to avoid a crash. Could it at least be pulverized into boulders small enough to burn up in Earth’s atmosphere? “Is it better to be shot by a high-velocity rifle bullet or a bunch of pellets from a shotgun?” asks Jewitt. “The answer is: The shotgun is better, because the smaller boulders are more likely to be cushioned or dissipated by the impact with the atmosphere.” 

India’s Lander Touches Down on the Moon. Russia’s Has Crashed

India’s Lander Touches Down on the Moon. Russia’s Has Crashed

And nations should avoid cluttering those spots with mechanical detritus, which could complicate future missions. Like campers heading into the backcountry, it’s important to think carefully about what you pack with you and what you take out, Birk says.

India’s success doesn’t mean the end of the race toward the moon’s south pole, but it does boost India’s standing. “This will certainly contribute to its status as a rising power with technological prowess. What’s happening in space is a reflection of what’s happening geopolitically on Earth,” says Cassandra Steer, an expert on space law and space security at the Australian National University in Canberra. And while Roscosmos suffered a setback, this isn’t the end of their moon program either, or their role in the new lunar competition. The Soviets beat the US at every stage of the 20th-century space race, Steer says, except for the landing of astronauts on the moon. Next, Russia intends to collaborate with China on a lunar research station.

Over the past decade, only China’s space program has achieved considerable success landing spacecraft on the moon, including its Chang’e 3, 4, and 5 missions in 2013, 2019, and 2020. India’s Chandrayaan-2 and Israel’s Beresheet lander failed in 2019, and Japan’s Ispace lander failed this April.

In fact, until China made its first landing, the moon had arguably been neglected for decades. NASA ended its Apollo mission in 1972, and the USSR’s Luna-24 mission in 1976 was the last successful lunar landing. That could mean limited institutional memory, especially for Russia, making it tough to develop and deploy new moon missions, Metzger says.

Over the past few decades, Russia has been trying to resuscitate its program, but with little success. Roscosmos has Luna-26 and Luna-27 planned for 2027 and 2029, as the agency aims to bring an orbiter and a larger lander to the moon. But their limited funding, thanks to sanctions following the Ukraine invasion, means these followup missions will likely be delayed, Zak says. And if the space agency decides to overhaul their propulsion system design after investigating the failure of Luna-25, that could be another reason for delays, he adds.

NASA has fared better with its Artemis program, which last year sent the uncrewed Artemis 1 to orbit the moon and is aiming for a crewed landing in 2026. But the program has faced its own challenges: NASA plans on using a SpaceX Starship lander, though, as its abortive test flight in April shows, Starship clearly has a long way to go. More than half of the 10 cubesat satellites deployed by Artemis 1 experienced technical glitches or lost contact with Earth, including the Japanese Omotenashi probe, which was unable to land on the moon as planned.

NASA has increasingly relied on commercial partners in a bid to boost the speed and lower the price of moon exploration—moving some of the costs onto businesses, rather than taxpayers. But these companies, too, are new players in the space race. In late 2024, NASA plans to send its Viper rover on an Astrobotic lander, though that company’s first moon lander, meant to demonstrate the technology, hasn’t even launched yet. NASA has also charged Firefly Aerospace, Intuitive Machines, and Draper with delivering a variety of payloads to the lunar surface over the next couple years.

In the meantime, nations like India, Japan, and Israel have begun moon programs from scratch. India next plans to collaborate with Japan on the Lunar Polar Exploration rover, which would launch no sooner than 2026.

“We have set the bar now so high. Nothing less spectacular than this is going to be inspiring for any of us in the future,” said Shri M. Sankaran, director of ISRO’s U R Rao Satellite Centre, speaking on today’s telecast. “We will now be looking at putting a man in space, putting a spacecraft on Venus, and landing on Mars. Those efforts have been ongoing for years. This success today will inspire us and spur us to take those efforts even more strongly to make our country proud again and again and again.”

Updated 8/23/2023 12:00 pm ET: This story was updated to correct the ISRO chief’s name.

The Big Bang’s Afterglow Reveals Invisible Cosmic Structures

The Big Bang’s Afterglow Reveals Invisible Cosmic Structures

Nearly 400,000 years after the Big Bang, the primordial plasma of the infant universe cooled enough for the first atoms to coalesce, making space for the embedded radiation to soar free. That light—the cosmic microwave background (CMB)—continues to stream through the sky in all directions, broadcasting a snapshot of the early universe that’s picked up by dedicated telescopes and even revealed in the static on old cathode-ray televisions.

After scientists discovered the CMB radiation in 1965, they meticulously mapped its tiny temperature variations, which displayed the exact state of the cosmos when it was a mere frothing plasma. Now they’re repurposing CMB data to catalog the large-scale structures that developed over billions of years as the universe matured.

“That light experienced a bulk of the history of the universe, and by seeing how it’s changed, we can learn about different epochs,” said Kimmy Wu, a cosmologist at SLAC National Accelerator Laboratory.

Over the course of its nearly 14-billion-year journey, the light from the CMB has been stretched, squeezed, and warped by all the matter in its way. Cosmologists are beginning to look beyond the primary fluctuations in the CMB light to the secondary imprints left by interactions with galaxies and other cosmic structures. From these signals, they’re gaining a crisper view of the distribution of both ordinary matter—everything that’s composed of atomic parts—and the mysterious dark matter. In turn, those insights are helping to settle some long-standing cosmological mysteries and pose some new ones.

“We’re realizing that the CMB does not only tell us about the initial conditions of the universe. It also tells us about the galaxies themselves,” said Emmanuel Schaan, also a cosmologist at SLAC. “And that turns out to be really powerful.”

A Universe of Shadows

Standard optical surveys, which track the light emitted by stars, overlook most of the galaxies’ underlying mass. That’s because the vast majority of the universe’s total matter content is invisible to telescopes—tucked out of sight either as clumps of dark matter or as the diffuse ionized gas that bridges galaxies. But both the dark matter and the strewn gas leave detectable imprints on the magnification and color of the incoming CMB light.

“The universe is really a shadow theater in which the galaxies are the protagonists and the CMB is the backlight,” Schaan said.

Many of the shadow players are now coming into relief.

When light particles, or photons, from the CMB scatter off electrons in the gas between galaxies, they get bumped to higher energies. In addition, if those galaxies are in motion with respect to the expanding universe, the CMB photons get a second energy shift, either up or down, depending on the relative motion of the cluster.

This pair of effects, known respectively as the thermal and kinematic Sunyaev-Zel’dovich (SZ) effects, were first theorized in the late 1960s and have been detected with increasing precision in the past decade. Together, the SZ effects leave a characteristic signature that can be teased out of CMB images, allowing scientists to map the location and temperature of all the ordinary matter in the universe.

Finally, a third effect known as weak gravitational lensing warps the path of CMB light as it travels near massive objects, distorting the CMB as though it were viewed through the base of a wineglass. Unlike the SZ effects, lensing is sensitive to all matter—dark or otherwise.

Taken together, these effects allow cosmologists to separate the ordinary matter from the dark matter. Then scientists can overlay these maps with images from galaxy surveys to gauge cosmic distances and even trace star formation.

What Will Ethical Space Exploration Look Like?

What Will Ethical Space Exploration Look Like?

The moon is interesting because there are valuable resources people want, like the ice on the poles. But even though the moon hasn’t been mined yet, and it seems like a big pile of resources that we can all just get our hands into, it’s limited, finite resources. And on the moon, they’re in finite areas: Most of the stuff you want from the moon is all in one place. The ice is at the poles. If you want uninterrupted sunlight, it’s at “peaks of eternal light” that get round-the-clock sunlight. If you want really cold areas to put your radio telescopes, for example, you need to be at the bottom of craters. That means we’re all going to be headed to the same place, fighting over the same things. 

The Outer Space Treaty does have some guidance. It says that if there are going to be activities that cause harmful interference, there needs to be consultation. Like, maybe I put down a radio telescope on the far side of the moon, and someone wants to put a launchpad next to it that’s going to kick up a lot of dust and block my view every time it launches, then they will have to do some consultation. But that’s really vague language at this point, and we haven’t really seen what that’s going to look like. We’ll find out.

What are the space ethics questions that people aren’t thinking enough about yet? 

Crime in space is a great example. I hadn’t really thought about it before. But now I’m talking to criminologists who are writing books about the idea of crime in space and how to handle it. We just need to connect people working on these issues with people who are decision-makers, policy-makers, people working in the space industry.

There are also people who want to start building orbital hotels and start taking paying customers. We might have the first pregnancy in space. This is part of the concern about private spaceflight in general. We’ve spent all these decades with all these space travelers who’ve been in a tightly monitored and regulated environment because they’re employees of national governments. Now there are a bunch of civilians who are just paying customers and won’t be following the same rules.

When it comes to ethical discussions on Earth, people use many different religious, cultural, and political frameworks. How do we find a code of ethics that represents our whole planet?

I don’t know if I have the answer to that. If we knew how to all get together and work out our differences and compromise and agree, we wouldn’t be having this big a problem with climate change as we’re having right now. But I think we can learn from climate change and nuclear disarmament. We can see what works, what hasn’t. I think part of the problem is this isn’t really about space, but about humans, and how we can solve big problems together.

We’re all often looking decades, even centuries, into the future. What should we do today to work toward building a just, equitable, and sustainable presence in space? 

Having these conversations is important, and learning more from people already working on these problems. I think this is useful even if it’s going to take centuries, past our lifetimes, to have permanent settlements in space. I think it’s useful because by thinking about these problems in space, we learn more about the injustices that are happening today on Earth.

It also helps us imagine more radical solutions to these problems—in a sci-fi context in space—than we would consider on Earth, where everything feels impossible some days. I think that’s a useful exercise to really imagine: If we were starting from scratch, how would we do it? And is there a way to get there from here, even on Earth?

Spotted a UFO? There’s an App for That

Spotted a UFO? There’s an App for That

The tech startup Enigma Labs wants to turn UFO sightings into data science. 

Previously, people who had seen strange lights darting around the sky could do no more than tell their friends—or call intelligence agencies. Soon, anyone with a smartphone will be able to use an app to report an unexplainable event as it happens.

Enigma Labs’ mobile app was released today, initially on an invitation-only basis as they work out the bugs, although they plan to make it available to the wider public. For now, it’ll be free to download and use, although the company could later charge for additional features. The company will not just be amassing new data—it has already gobbled up data on around 300,000 global sightings over the past century and included them in their system—and while their dataset will be available to the public, their algorithms for assessing it will not.

“At our core, we’re a data science company. We’re building the first data and community platform exclusively dedicated to the study of unidentified anomalous phenomena,” says Mark Douglas, chief operating officer of the New York–based company.

grid of shapes

Courtesy of Enigma Labs

Part of their goal is to reduce the stigma of reporting something unexplainable—even if the viewer doesn’t actually think it’s visiting aliens. (For the record, some government agencies and companies like Enigma Labs now use the term UAPs instead of UFOs: unidentified anomalous phenomena, rather than unidentified flying objects. The change is meant to encompass a broad range of objects that might not have an extraterrestrial origin, and to make the terminology sound less pejorative.)

Identifying an unknown and distant object or explaining a phenomenon one has never seen before poses a unique challenge. Nevertheless, the app asks users structured questions, like when and where in the sky the user saw something, and approximately what shape the object had. It also gives them space to tell their sighting story and provide more details, and they can upload a photo or video. It’s a bit like citizen science projects in which volunteers help classify telescope images of galaxies, but in this case the images are submitted by volunteers and most of the classification is done by an algorithm.

The company wants to do more than just ingest lots of data though: They want to apply their proprietary models to rule out things that are not UAPs, such as by determining whether there’s lightning or unclassified aircraft nearby. And they want to filter the credibility of the data sources as well, distinguishing between “highly credible military pilots, trained observers with corroboration from multiple sensors, and then at the opposite end of spectrum … a single witness who maybe had a few drinks too many and saw a point of light in a sky,” Douglas says.

“The core issue to studying this has been a data problem: ‘What is credible, what is not, who is credible, who is not?’” he argues. “What we’re trying to do is bring a level of standardization and rigor to that.”

Of course, the challenge will be applying scientific standardization to something that might not be scientific at all. Eyewitness testimony is notoriously unreliable, and people interpret what they see based on factors like current events and their scientific, political, and cultural backgrounds. “The data you’re getting is socially constructed,” says University of Pennsylvania historian Kate Dorsch, who specializes in scientific knowledge production.

submission page screenshot

Courtesy of Enigma Labs

UFO sightings began as an American obsession following World War II and the Roswell incident in 1947, when people in New Mexico found mysterious debris that may (or may not) have come from a crashed military balloon. Sightings quickly spread across most of the world, Dorsch says, and interest in Roswell, as well as the US’s and USSR’s nascent space programs, may have encouraged people to think of lights in the sky as alien technology. But, she continues, there were fewer UFO sightings after the Soviet Union launched the Sputnik satellite in 1957—when people saw something weird in the sky, they chalked it up as a human-made spacecraft. And the geopolitics of where you live matters, too. Today, she says, when Germans witness strange phenomena, they often attribute them to Russian and American-made craft. “When you’re looking for something in particular, that is what you’ll see,” she says.

Government agencies have always been interested in reports of UFOs for national security reasons, since sightings of flying saucers might actually be sightings of a rival’s secret aircraft. (Or, if the craft was actually the nation’s own classified project, descriptions of the sighting might reveal how it appears to others.)