Enlarge (credit: ASI/NASA )

In 2022, NASA's Double Asteroid Redirect Test (DART) smashed into the asteroid Dimorphos in a successful test of planetary defense technology. That success was measured by a significant shift in Dimorphos' orbit around the larger asteroid Didymos. Since then, a variety of observatories have been analyzing the data to try to piece together what the debris from the impact tells us about the structure of the asteroid.

All of those observations have taken place at great distances from the impact. But DART carried a small cubesat called LICIACube along for the ride and dropped it onto a trailing trajectory a few weeks before impact. It took a while to get all of LICIACube's images back to Earth and analyzed, but the results are now coming in, and they provide hints about Dimorphos' composition and history, along with why the impact had such a large effect on its orbit.

Tracing debris

LICIACube had both narrow and widefield imagers on board (named LEIA and LUKE via some carefully chosen backronyms). It trailed DART through the impact area by about three minutes and captured images starting about a minute before the impact and continuing for over five minutes afterward.

Enlarge / Each panel shows the modeled effects of early Earth’s bombardment. Circles show the regions affected by each impact, with diameters corresponding to the final size of craters for impactors smaller than 100 kilometers in diameter. For larger impactors, the circle size corresponds to size of the region buried by impact-generated melt. Color coding indicates the timing of the impacts. The smallest impactors considered in this model have a diameter of 15 kilometers. (credit: Simone Marchi, Southwest Research Institute)

When it comes to space rocks slamming into Earth, two stand out. There’s the one that killed the dinosaurs 65 million years ago (goodbye T-rex, hello mammals!) and the one that formed Earth’s Moon . The asteroid that hurtled into the Yucatan peninsula and decimated the dinosaurs was a mere 10 kilometers in diameter. The impactor that formed the Moon, on the other hand, may have been about the size of Mars. But between the gigantic lunar-forming impact and the comparatively diminutive harbinger of dinosaurian death, Earth was certainly battered by other bodies.

At the 2023 Fall Meeting of the American Geophysical Union, scientists discussed what they’ve found when it comes to just how our planet has been shaped by asteroids that impacted the early Earth, causing everything from voluminous melts that covered swaths of the surface to ancient tsunamis that tore across the globe .

Modeling melt

When the Moon-forming impactor smashed into Earth, much of the world became a sea of melted rock called a magma ocean ( if it wasn’t already melted ). After this point, Earth had no more major additions of mass, said Simone Marchi , a planetary scientist at the Southwest Research Institute who creates computer models of the early Solar System and its planetary bodies, including Earth. “But you still have this debris flying about,” he said. This later phase of accretion may have lacked another lunar-scale impact, but likely featured large incoming asteroids. Predictions of the size and frequency distributions of this space flotsam indicate “that there has to be a substantial number of objects larger than, say, 1,000 kilometers in diameter,” Marchi said.

Enlarge / The dusty debris from the DART collision dominates this image, but there are boulders present, too. (credit: NASA, ESA, David Jewitt (UCLA) )

NASA's Double Asteroid Redirect Test (DART) mission was a success from the perspective of planetary defense, as it successfully shifted the orbit of an asteroid . But the mission had a scientific element to it, and we're still sifting through the debris of the collision to determine what the impact tells us about the asteroid. That's difficult due to the distance to the asteroid and the low amounts of light that reflect off the debris.

Today, a paper was released by a team that analyzed images of the aftermath using the Hubble Space Telescope. They've spotted dozens of boulders that collectively would have originally made up 0.1 percent of the mass of Dimorphos, DART's target. And while they're all moving very slowly from the site of the collision, some of them should be able to escape the gravity of the double asteroid system.

Knocking rocks

The images taken by DART immediately prior to its demise suggest that Dimorphos was a rubble pile, a mixture of boulders, small rocks, and dust barely held together by their mutual gravitational pull. So what happens when a relatively solid object, like the DART spacecraft, hammers an asteroid at high speed?

Enlarge / An artist's illustration of NASA's two Janus spacecraft as they would have appeared in space. (credit: Lockheed Martin )

Two small spacecraft should have now been cruising through the Solar System on the way to study unexplored asteroids, but after several years of development and nearly $50 million in expenditures, NASA announced Tuesday the probes will remain locked inside a Lockheed Martin factory in Colorado.

That’s because the mission, called Janus, was supposed to launch last year as a piggyback payload on the same rocket with NASA’s much larger Psyche spacecraft , which will fly to a 140-mile-wide (225-kilometer) metal-rich asteroid—also named Psyche—for more than two years of close-up observations. Problems with software testing on the Psyche spacecraft prompted NASA managers to delay the launch by more than a year.

An independent review board set up to analyze the reasons for the Psyche launch delay identified issues with the spacecraft’s software and weaknesses in the plan to test the software before Psyche’s launch. Digging deeper, the review panel determined that NASA’s Jet Propulsion Laboratory, which manages the Psyche mission, was encumbered by staffing and workforce problems exacerbated by the COVID-19 pandemic.

Enlarge / The Geminids put on quite a show each year. (credit: NASA.gov )

Each year, skywatchers get to gaze at the spectacle of the Geminids streaking through the night sky from mid-November through late December. However, this meteor shower is highly unusual, and not only because it is one of the easiest to view.

Meteor showers usually originate from comets that fly close to the Sun. Comets are made of frozen gasses, dust, and rock, and the Sun’s heat vaporizes some of that gas and releases it into space, dislodging debris that eventually falls to Earth. But the Geminids are exceptional because they originate from an asteroid instead of a comet . Asteroid 3200 Phaeton is the source of this trail of debris, but asteroids are not affected by solar heat the same way as comets, so it’s unclear why Phaeton has left a trail of debris.

NASA scientists who analyzed data from the space agency’s Parker Solar Probe have now finally found the most likely answer to the mystery of how the Geminids formed: a catastrophic event. “The Geminids may have formed via a more violent, catastrophic destruction of bodies that transited very near to the Sun,” the scientists said in a study recently published in The Planetary Science Journal .

Enlarge / Artist’s illustration shows the ejection of a cloud of debris after NASA’s DART spacecraft collided with the asteroid Dimorphos. (credit: ESO/M. Kornmesser)

Last September, the Double Asteroid Redirect Test, or DART, smashed a spacecraft into a small binary asteroid called Dimorphos, successfully altering its orbit around a larger companion. We're now learning more about the aftermath of that collision, thanks to two new papers reporting on data collected by the European Southern Observatory's Very Large Telescope . The first, published in the journal Astronomy and Astrophysics, examined the debris from the collision to learn more about the asteroid's composition. The second, published in the Astrophysical Journal Letters, reported on how the impact changed the asteroid's surface.

As we've reported previously , Dimorphos is less than 200 meters across and cannot be resolved from Earth. Instead, the binary asteroid looks like a single object from here, with most of the light reflecting off the far larger Didymos. What we can see, however, is that the Didymos system sporadically darkens. Most of the time, the two asteroids are arranged so that Earth receives light reflected off both. But Dimorphos' orbit sporadically takes it behind Didymos from Earth's perspective, meaning that we only receive light reflected off one of the two bodies—this causes the darkening. By measuring the darkening's time periods, we can work out how long it takes Dimorphos to orbit and thus how far apart the two asteroids are.

Before DART, Dimorphos' orbit took 11 hours and 55 minutes; post-impact, it's down to 11 hours and 23 minutes. For those averse to math, that's 32 minutes shorter (about 4 percent). NASA estimates that the orbit is now "tens of meters" closer to Didymos. This orbital shift was confirmed by radar imaging. Earlier this month , Nature published five papers that collectively reconstructed the impact and its aftermath to explain how DART's collision had an outsize effect. Those results indicated that impactors like DART could be a viable means of protecting the planet from small asteroids.

Enlarge / A look at an alternate reality where vector displays never died.

Atari's new 50th-anniversary compilation is stuffed with historical filler, but one new game contained in the package won't let me go. I'm talking about Vctr Sctr , a retro-style arcade shooter that melds the addictive gameplay of classics like Asteroids and Tempest with modern gameplay concepts.

As a package, Atari 50: The Anniversary Collection sets a new high-water mark for retro video game compilations. The collection's "timeline" feature deftly weaves archival materials like design documents and manuals, explanatory context and contemporary quotes from the game's release, and new video interviews with game creators into an engaging, interactive trip through gaming history.

But while the presentation shines, the games contained within Atari 50 often don't. Sure, there are a few truly replayable classics on offer here, especially in the games from Atari's glorious arcade era. That said, the bulk of Atari 50 's selection of over 100 titles feels like filler that just doesn't hold up from a modern game design perspective. Dozens of "classic" Atari games—from 3-D Tic-Tac-Toe on the Atari 2600 to Missile Command 3D on the Jaguar—boil down to mere historical curiosities that most modern players would be hard-pressed to tolerate for longer than a couple of minutes.