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Back within the early Nineties, Dave Tholen, an astronomer on the College of Hawaii, had an mental itch he couldn’t fairly scratch. His specialty was discovering and mapping asteroids—he had even served on an early “detection committee” that NASA had helped arrange. The committee had really helpful that Tholen seek for asteroids in what’s often called the “opposition area” of the sky—the half reverse the solar, with Earth in between—as a result of that’s the place their fashions had steered most asteroids could be discovered.
Tholen, nevertheless, had different concepts. “It appeared like round reasoning,” he instructed me. “You’re principally saying that the very best place to look within the sky is the place we now have been wanting.” What if, he questioned, he have been to seek for asteroids whose orbits lay between the Earth and solar? “One thing like Venus or Mercury, however on a extra eccentric orbit,” he described it to me. If it turned an influence hazard, he mentioned, “we’d by no means see it coming, as a result of it’s all the time within the daytime aspect of the sky.”
After years of struggling to safe funding, in 2004 he lastly obtained the chance to carry out his survey with the Subaru Telescope atop Hawaii’s Mt. Mauna Kea. On his final evening on the telescope, he and a colleague noticed one thing shifting rapidly, sometimes the lifeless giveaway of a near-Earth object. They instantly flew to Arizona, the place they continued their observations on Kitt Peak. However as a substitute of choosing up what they’d seen within the higher left quadrant of their instrument’s viewing display screen—the place they anticipated it—they noticed one thing within the decrease proper. The subsequent evening, additional statement confirmed their preliminary suspicions: It was the identical object they’d noticed in Hawaii. The 2 despatched their information to the Minor Planet Heart, which christened the asteroid “2004 MN4.”
If the massive one comes, and we cease it, we are able to hint saving the world to the hobbyists.
As extra observations got here in, and extra computations have been made, a realization dawned, Tholen mentioned. “Hey, that is going to come back actually shut in 2029, so shut it might hit.” The asteroid was rechristened “Apophis”—the Greek identify for an evil Egyptian deity. It was an estimated 1,300 miles in width, larger than the thing that streaked into Russian skies in 1908, unleashing 550 kilotons of downburst and obliterating 772 sq. miles of Siberian forest (the atmospheric stress in Britain was affected). If Apophis have been to hit, the blast drive could possibly be on the order of 1,000 megatons of TNT—the equal of many nuclear weapons, felt without delay—flattening a whole bunch of sq. miles and, if it have been to land in a densely populated area, killing thousands and thousands.
Apophis, projected to have a 1 in 62 likelihood of placing the planet, surged to degree 4 on the Torino Scale, a system developed to measure the chance posed by asteroids to Earth. This degree signifies “a detailed encounter, meriting consideration by astronomers”—just about panic stations within the Close to-Earth Object world. Astronomers globally scrambled to make calculations, whereas The New York Occasions questioned if “Apophis deserves to be added to our common record of doomsday worries.” Quickly, although, the menace started to decrease, as additional calculations with optical and radar telescopes decided that its influence trajectory was merely a “shut method.”
Apophis was downgraded to degree zero, turning into only one rock amongst many, orbiting the solar. Like an getting older pop star, it fell off the “Threat Checklist” of the European Area Company’s Close to-Earth Objects Coordination Centre—the Billboard charts of potential inter-planetary hazard. However in 2029, on Friday, April 13, Apophis will move inside 19,794 miles of Earth—that’s nearer than the satellites that deliver you your cable TV. It’s the largest, closest asteroid to ever come our means with advance discover, seen to the bare eye. Tholen mentioned that whereas Apophis’s present trajectory is just not a trigger for concern, its final course is ceaselessly tinged with cosmic uncertainty, because of fluctuations in daylight that give slight pushes to an asteroid, and different unpredictable gravitational phenomena.
Which suggests the asteroid will perpetually lurk on the margins of consideration for the following generations of astronomers. “Can the tidal pull of the Earth change the form of the asteroid? Can it change the spin state of the asteroid?” Tholen asks. “I’m going to take a wait-and-see perspective.”
This has been the narrative that the majority of us know of contemporary near-Earth-object analysis. An asteroid is detected—it could possibly be new, it could possibly be one thing outdated, displaying up in a brand new place. Its trajectory, deemed to come back uncomfortably near Earth, offers it an alarming-sounding rating on a scale none of us actually perceive. The media responds with provocative headlines and pictures from motion pictures like Deep Influence. Step by step, science does its factor and determines the chance to be marginal. The world, like all of the objects floating round it in house, strikes on.
However monitoring asteroids is much less a recreation of absolute uncertainty than lowering uncertainty. Apophis was a false alarm this time, however possibly on its subsequent method—if you and I and Dave Tholen may have shuffled off this mortal coil—the numbers in our cosmic on line casino will are available in another way. As somebody who has really dreamt of an asteroid placing the Earth (it’s not as unusual a dream as you may suppose), I discover this lengthy recreation deeply fascinating.
In 2023, I got down to meet the individuals who spend a very good a part of their day fascinated with an issue that appears fairly far down within the world “hierarchy of wants.” Which it’s—till it isn’t. What number of different threats within the fashionable world, artifical or pure, could be mentioned to be extinction-level occasions? After years of fevered dialogue in small rooms, drafting out-there concepts through back-of-the-napkin sketches, scientists are discovering a option to handle this menace, actually, head-on. I wasn’t certain if this was sci-fi wargaming—fantasy soccer for the interstellar-minded—or an finally hopeful signal that the world, within the face of this, and different, imminent threats, might pool its collective intelligence to save lots of itself.
Currently, based on NASA, there are 1,351,594 identified asteroids in our photo voltaic system. The quantity, detailed on an company internet web page, will increase slowly however repeatedly, like a type of “Days Since Final Accident” indicators in a manufacturing unit, as astronomers proceed to select them out of the heavens. The majority of those “rocky, airless remnants,” as NASA phrases them, are dispersed all through what’s often called the “fundamental asteroid belt,” the torus-shaped sea of historic flotsam between Mars and Jupiter.
Round 30,000 asteroids are designated “Close to-Earth Objects,” which means they’ve a trajectory that brings them inside 0.03 astronomical items—round 28,000 miles—of Earth. Most of those asteroids will sail harmlessly by; and but, over the past 100 years, there have been two meteor-caused atmospheric blasts that, had the geography and inhabitants density been a bit totally different, might have flattened whole cities and killed a whole bunch of 1000’s of individuals. Then there are all these house rocks which might be too small to rely. Some 100 of those palm-sized objects—name it house hail—survive their fiery descent and hit terra firma day-after-day. Christian Köberl, a professor of influence analysis and planetary geology on the College of Vienna, instructed me that Earth, owing to its gravitational pull, is “in the course of a cosmic taking pictures gallery.”
And but, it wasn’t way back that the specter of asteroids was barely on NASA’s radar. In 1980, the group was conscious of solely 51 near-Earth asteroids. Asteroid detection and protection might by no means have gotten off the bottom have been it not for a handful of scientists and others within the aerospace group who have been obsessed by the evening sky flotsam. Sometime, if the massive one comes, and we cease it, we are able to hint saving the world to the hobbyists.
That very same yr, Lindley Johnson graduated with a level in astronomy from the College of Kansas. Right now, Johnson is the pinnacle of NASA’s Planetary Protection Coordination Workplace. Once I met Johnson, he wore a blue pullover marked by an attention-grabbing embroidered badge that depicts a determine standing atop a citadel tower, holding a telescope pointed on the evening sky. Under have been the phrases Hic Sevare Diem: “Right here to save lots of the day.” It was designed, Johnson instructed me, by Michael Okuda, the longtime designer for Star Trek. “NASA’s not actual large on logos,” Johnson mentioned, smiling. “However they made an exception.”
After school, Johnson joined the Air Power, the place he labored on house surveillance methods. Within the early Nineties, he was approached by Tom Gehrels, an astronomer on the College of Arizona, about leveraging new digital imaging expertise to assist hunt asteroids. Conversations with Gehrels and different asteroid hunters like astronomers Gene and Caroline Shoemaker additional piqued his curiosity in monitoring asteroids. “This actually is a nationwide safety subject,” he recalled considering on the time. “Being impacted by an asteroid could possibly be a foul day not just for a specific nation, however for the world.”
Not lengthy afterward, the Air Power wished to fee a research of what new capabilities it wanted by the yr 2020. Johnson stepped ahead and mentioned it wanted to be ready for the menace from an asteroid. Air Power employees have been nonplussed. However Johnson persevered and wrote “Getting ready for Planetary Protection.” “I virtually didn’t get permission to jot down that paper,” he mentioned. His colleagues “thought it was too summary.”
Earth is in the course of a cosmic taking pictures gallery.
In July 1994, the nascent motion had a foundational second, when the comet Shoemaker-Levy 9 slammed into Jupiter in a damaging rain of fragments. It was the primary dwell viewing of an object from house colliding with a planet. One of many items of the comet (“Fragment G”) left an Earth-sized crater. The concept of a momentous influence from house immediately didn’t look like one thing for the archaeological file (just like the dinosaur-killing influence, 65 million years in the past, within the Yucatan Peninsula). “A Risk to the Earth is No Longer a Joke,” declared The New York Occasions.
Later that yr, Congress directed NASA to seek for and monitor near-Earth objects bigger than 1 kilometer. In 1998, the temporary was expanded, tasking NASA to create a program “to detect, monitor, catalog, and characterize” not less than 90 p.c of near-Earth objects bigger than 460 toes in diameter by the yr 2020. Johnson helped lead the search effort. However because the deadline handed, the company had solely discovered a fraction of the asteroids that fashions steered existed. “We’re solely 42 p.c full after 25 years of looking out,” Johnson mentioned. “On the present price it’ll take one other 30 to 40 years to finish the catalog.”
Asteroid, in Greek, means “star-like,” which is how they have a look at an awesome distance. Discovering them is a bit like the youngsters’s recreation of “spot the distinction.” You are taking repeated footage of the identical piece of sky, and “you search for what has moved,” mentioned Richard Binzel, a professor of astronomy at MIT. From that blurred hint of sunshine, he defined, you attempt to decide the asteroid’s “orbital components”—a six-part set of coordinates that reveals not solely the place it’s going, however, by “linking” these coordinates with earlier surveys, the place it’s been. And the longer you watch an asteroid, for months, or higher but years, the higher you’ll be able to decide the place it’s going. Binzel in contrast it to a baseball outfielder attempting to catch a fly ball. “The ball first comes off the bat and the middle fielder’s going, ‘Do I are available, do I come out?’ After which as you see increasingly of the trail, you’re increasingly sure.”
In 1999, Binzel helped design the Torino Scale. As with the Richter or Saffir-Simpson scale, the concept was to offer scientists a jargon-free means of speaking severity. The vary goes from degree zero to Stage 10—zero means no likelihood of collision or will dissipate even when it sneaks into our environment; 10 signifies that you shouldn’t even hassle working for the hills, which is able to in all probability be underwater anyway. Yearly, a handful of asteroids get a degree 1 designation, which can begin your pulse racing, but it surely merely means: “A routine discovery by which a close to move is predicted that poses no uncommon degree of hazard.”
As extra information are available, these asteroids are sometimes downgraded to degree zero. However typically not earlier than a level of alarmist information consideration, exasperating scientists like Binzel. “Mainly, a Tesla-sized asteroid passes by the Earth-moon system a number of instances per week,” he mentioned. “It’s simply the character of the enterprise.” The asteroids have all the time been there, however “we’re simply now more and more capable of see them.”
Mario Juric is among the world’s main asteroid hunters. A professor of astronomy on the College of Washington, Juric instructed me asteroids are the rationale he’s an astronomer immediately. As a highschool physics pupil in Zagreb, Croatia, he chanced upon an area DIY astronomy program whose mantra, as Juric described it, was “let’s go construct telescopes, let’s go discover asteroids.” Earlier than lengthy, he was writing software program to robotically discover near-Earth objects. “By the point I obtained to my senior yr I’d already discovered 1000’s,” he says, and what had been a passion turned a profession.
When Juric began recognizing asteroids within the Nineties, there have been solely 10,000 or so identified. The primary, Ceres, had been found in 1801 by the star-cataloging Italian priest Guiseppe Piazzi (Ceres is so large that astronomers have since reclassified it as a dwarf planet). “It took us a few centuries to get to the primary 10,000,” he mentioned. “It took a further 30 or so years to get to 1.3 million.”
Within the subsequent few years, that quantity will seemingly soar to five million, largely because of an effort—by which Juric has been a primary mover—to construct a sky-sweeping telescope on the Vera C. Rubin Observatory in Chile (named for the pioneering American astronomer identified for locating darkish matter, amongst different issues). The state-of-the-art telescope makes use of the best decision digital digicam on this planet. It is going to scan and file your complete evening sky each three days, as a part of the Observatory’s 10-year Legacy Survey of Area and Time. (The Observatory reviews science operations will start in late 2025.) The brand new telescope will permit Juric to catalog near-Earth objects with unprecedented scope and acuity.
On this work, Juric is getting an help from The Asteroid Institute, a venture of the B612 Basis. B612, named for the asteroid house of Antoine de Saint-Exupery’s Little Prince, is a nonprofit cofounded by ex-astronauts Ed Lu and Russell “Rusty” Schweickart in 2002 to function a type of planetary watchdog towards threats from house. Alongside the best way, B612 has picked up supporters like Queen guitarist Brian Could, an astrophysicist who helped begin “Asteroid Day,” which is well known annually on June 14.
Lu, who labored for Google Maps as soon as his house days have been over, instructed me that the hassle to construct correct road maps—to make use of in, say, self-driving automobiles—isn’t so totally different from monitoring near-Earth objects. “Mapping must be continually up to date,” he mentioned. “At some degree, most issues don’t change, however each every now and then, one thing does. It’s the identical factor within the photo voltaic system.” In contrast to floor mapping, nevertheless, in house, “every part is shifting—you must speak about trajectories, not areas.”
Additional complicating issues is the truth that asteroids can go lacking. Lu mentioned it isn’t as a result of “they’re altering course drastically,” however somewhat that “in some instances, we don’t have an excellent estimate of the orbit as a result of we don’t have observations of these asteroids over a protracted sufficient time frame.” And as soon as an asteroid has slipped out of view, the “longer it has been since we’ve final noticed that asteroid, the extra unsure our prediction is of the place to look.” There are some asteroids that have been as soon as identified, he mentioned, however now “we couldn’t even level a telescope at them.”
Lu mentioned, “quite a bit have been misplaced, those that weren’t effectively tracked to start with.” B612 goals to resolve this downside by stitching collectively the previous and current observations of the world’s telescopes into “one big unified information set.” The longer you’ve been watching an asteroid, the additional into the longer term you’ll be able to predict its motion. Asteroid monitoring is the final word lengthy recreation.
Finding and monitoring a doubtlessly hazardous near-Earth object is one factor. However what if, to paraphrase Marx, you wished not simply to grasp the world, however to vary it? Or not less than change its orbit.
For many years, scientists, engineers, and others within the planetary protection group have been theorizing on methods to interrupt the journey of an Earth-bound asteroid. One of many theoretical weapons within the quiver is the so-called “gravity tractor,” which entails directing a spacecraft towards an asteroid—to not destroy it, however to journey alongside of it, counting on its gravitational attraction to drag it to a brand new orbit, like an outer house model of a tugboat shepherding a container ship by New York Harbor. One other is an ion beam “shepherd,” by which a spacecraft would direct a high-velocity ion beam (a expertise already used to assist maintain satellites on their correct orbit) towards an asteroid, hitting it with sufficient drive as if the asteroid itself have been geared up with an ion booster. Some have proposed blasting asteroids with lasers—to not demolish them, per the online game, however to deflect them. A extra low-tech method includes blasting the asteroid with giant “paintballs”—altering the reflectivity of the asteroid which, over time, modifications its rotation. Even getting a direct hit on an asteroid that’s spinning is usually a problem, which is why one analysis staff advocates a “tethered photo voltaic sail,” which, when hooked up to an asteroid, would successfully seize it.
None of those approaches—broadly grouped into “excessive impulse” and “gradual push” options—have made it previous the theoretical stage. That every one modified in 2021 when the primary rocket to deflect an asteroid was launched. The goal was Dimorphos, a 5-billion-kilogram asteroid moonlet known as Dimorphos, orbiting a bigger asteroid known as Didymos. Dimorphos was the proper Goldilocks asteroid: sufficiently far-off that it posed no precise danger to Earth, however shut sufficient for a spacecraft to achieve comparatively rapidly.
A Tesla-sized asteroid passes by the Earth-moon system a number of instances per week.
Almost a yr after it launched, on Sept. 26, 2022, to be actual, the rocket, known as DART, for Double Asteroid Redirection Take a look at, smashed into Dimorphos. It was a recreation of cosmic billiards. NASA shot its cue ball throughout the photo voltaic system at exactly on the proper angle to knock Dimorphos off its trajectory. That shot represented a colossal human achievement. “Humanity first moved an asteroid,” as Nancy Chabot, a planetary scientist with Johns Hopkins College Utilized Physics Laboratory, sums it up. This was, she says, no small process: “It was an enormous problem hitting a small asteroid, which you’ve by no means seen earlier than, that’s 7 million miles away and shifting at 6.1 kilometers per second.”
However DART has its limitations. The nearer an asteroid involves Earth, the better the required angle of deflection, the larger the drive wanted to deflect. After which there’s the scale of DART itself: It weighed lower than the famed defensive position of the 1985 Chicago Bears. What if an asteroid larger than Dimorphos, and nearer than Dimorphos, was headed our means? “We would wish 100 DARTs,” defined Andy Rivkin, an engineer with the Utilized Physics Laboratory. Or extra as a result of a few of the DARTS “would in all probability fail.”
Caleb Scharf, senior scientist for astrobiology at NASA’s Ames Analysis Heart, has written in Nautilus that even a comparatively small-scale effort like DART—the “first important, focused engineering of the basic construction of our photo voltaic system in 4 billion years”—might result in some “totally unforeseeable emergency issues within the refined chaos of orbital dynamics.” Like a high-order recreation of billiards, you may sink the eight ball, however find yourself scratching the cue ball.
Asteroid deflection is now a technological actuality. However might we—and by we I primarily imply rich international locations with house capabilities—summon the collective organizational and political will to mount a thoroughgoing protection within the face of a identified menace? The specter of local weather change means that scientific consensus of an precise hazard doesn’t robotically translate into nations taking efficient countermeasures.
Regardless of the technical talents we’d possess to deflect or destroy an incoming asteroid, a number of things, not the least of that are political, would have to be resolved briskly, and with worldwide cooperation. To recreation out this situation, a bunch known as the Planetary Protection Convention—everybody calls it “the PDC”—has gathered biannually since 2004 to consider an issue that’s statistically unlikely and completely believable.
In spring 2023, I traveled to Vienna, Austria, the positioning of the newest PDC assembly. In Boardroom D on the United Nations headquarters, Kelly Quick, head of NASA’s Close to-Earth Objects Observations Program, knowledgeable the assembled viewers that the company had detected an asteroid—recognized as 2023 PVC—that had a 1 p.c likelihood of impacting the Earth on Oct. 22, 2036.
The viewers—comprised of 150 scientists, catastrophe response managers, authorized specialists, former astronauts, ethicists—grew quiet, save for the frenetic dance of fingers on laptops. They have been seated at lengthy tables that radiated outward in a semi-circular arc, every station geared up with a simultaneous translation headset, some bearing nation placards. The room, paneled in Scandinavian blonde wooden, exuded a procedural air, possibly the faint whiff of some previous war-crimes trial. Via a excessive window within the nook of the room, a bunch of badge-wearing guests regarded down.
The danger hall, Quick famous, prolonged from the South Pacific to the Southern Indian Ocean, with big swaths of North America, Europe, and Africa sitting within the influence zone. The harm will likely be “regional to continental.” She added, as if by comfort, “1 p.c means there’s a 99 p.c likelihood it wouldn’t influence.”
However what has put NASA on alert—in addition to a complete constellation of affiliated governmental companies and consortiums, starting from the Worldwide Asteroid Warning Community to the United Nations Workplace for Outer Area Affairs to the Area Mission Planning Advisory Group—is the scale of 2023 PVC. Paul Chodas, who heads the NASA Earth Commentary program on the Jet Propulsion Laboratory, chimed in. “It could possibly be within the vary of 220 to 660 meters. If it’s a darkish object, it could possibly be a lot bigger,” he mentioned. The influence drive, Chodas continued, could possibly be within the vary of “54 megatons to 5 and a half gigatons.” To place that into context, the atomic bomb dropped on Hiroshima had a blast yield of 15 kilotons—virtually a rounding error in comparison with 2023 PVC.
Lorien Wheeler, who research asteroid influence danger at NASA’s Ames Analysis Heart, instructed the room to anticipate “a big floor influence or low airbust inflicting a extremely damaging blast wave and fireplace.” Given the scale of PVC 2023, she added, “the harm severities are anticipated to achieve unsurvivable ranges.” Issues hardly get higher from there, as gasses, aerosols, and supplies are lofted into the environment. “The local weather suggestions loops can be virtually instantaneous,” mentioned Lara Mani, with the College of Cambridge’s Heart for Existential Threat. “Influence winter,” she known as it.
In case your imaginative and prescient for planetary protection features a nuclear weapon, you will have an issue.
The tip of the world ends with a espresso break. As we sipped darkish roast within the hallway, Planetary Protection Convention founder Invoice Ailor instructed me the convention was launched on a whim. Ailor was working for the Aerospace Company again within the early 2000s when, he mentioned, “an Air Power common got here and principally mentioned, ‘suppose an asteroid is headed for Earth? What are we going to do about it?’ ” On the inaugural convention, somebody requested the query of the best way to notify the White Home within the occasion a critical menace was detected. “There was no path on the time,” Ailor mentioned (there now could be).
Again in Boardroom D, attendees hashed out a response to 2023 PVC. Brent Barbee, an engineer with NASA’s Goddard Area Heart, famous that an asteroid deflection mission might, owing to the scale of 2023 PVC, require the launch of as much as 1,300 “Falcon Heavies”—SpaceX’s signature rocket—to place the asteroid off an Earth trajectory. Something lower than a full deflection might dump the asteroid in an ocean, the place it might set off huge tsunamis.
Noting that something lower than a full deflection could possibly be catastrophic, Detlef Kochny, a planetary protection specialist with the ESA, known as for the “nuclear choice”—utilizing the blast drive of a weapon to shift the asteroid. Individuals had been fascinated with utilizing nuclear weapons towards asteroids for the reason that peak of the Chilly Warfare. In 1967, for an train in “methods engineering,” an MIT professor carried out a seminar that theorized a nuclear counterstrike on an asteroid—1566 Icarus—that was due for a “shut move” of Earth in 1968 (a detailed move nonetheless being 38 instances farther than the moon). The researchers steered that the six Saturn rockets then in manufacturing, every bearing 100 megatons of nuclear explosives, can be required to cease the asteroid—a bit problematic, as the biggest nuke within the U.S. arsenal was 25 megatons. There’s one other downside with the nuclear method. It’s unlawful.
“In case your imaginative and prescient for a planetary protection mission consists of the usage of a nuclear weapon, you will have an issue,” mentioned David Koplow, a legislation professor at Georgetown College. “Don’t transcend this level with out your legal professional.”
Nonetheless, after a long time of relative inertia, “planetary protection,” mentioned Matt Daniels, assistant director on the White Home Workplace of Science and Expertise Coverage, “has hit an inflection level.” This yr, the European Area Company will launch “HERA,” a spacecraft that may autonomously rendezvous with Dimorphos to carry out a autopsy on DART’s bullseye and “flip the grand-scale experiment right into a well-understood and repeatable planetary protection approach.” This yr additionally sees the launch of NASA’s Close to-Earth Object Surveyor infrared house telescope, in addition to the completion of the survey telescope in Chile—two long-awaited devices that may dramatically quicken the documentation of potential asteroid threats. Spacecraft from the U.S. and Japan are presently returning to Earth, laden with asteroid samples. What may need as soon as appeared a fringe gathering within the small rooms of nationwide laboratories now appeared extra like some heady Davos of the near-Earth object scene.
So are the planetary defenders able to Hic Sevare Diem—save the day? “The danger hasn’t modified,” mentioned Johnson, director of NASA’s Planetary Protection Coordination Workplace. “The identical asteroids which might be there now have been there a millennia in the past.” What has modified, he steered, “is our understanding of the chance.” And it takes a very long time, he mentioned, for that understanding to permeate by society. “The lights don’t immediately go on and folks perceive that is one thing that the taxpayer’s cash needs to be spent on,” he mentioned. It doesn’t harm that the universe, every now and then, throws up a reminder.
Just a few weeks after I returned to my house, in Madison, New Jersey, from the convention in Vienna, a meteor—a “mango-sized rock” as one outlet dubbed it—tore by the roof of a home in Hopewell, New Jersey, with such drive that its rebound off the ground tore one other gap by the roof. The 4.5-billion-year-old “hammer stone,” as such fragments are dubbed after they strike human-made issues, landed lower than an hour away from me—a mere Planck size within the scale of the universe. It appeared just a little coda to the convention, a footnote from outer house: For all our elevated energy in patrolling the heavens, you’ll be able to by no means fairly make sure that nothing goes to fall out of the sky. 
Lead illustration by Mark Belan
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