Latest news with #Near-EarthObject
Yahoo
21-05-2025
- Science
- Yahoo
US Representatives worry Trump's NASA budget plan will make it harder to track dangerous asteroids
When you buy through links on our articles, Future and its syndication partners may earn a commission. On Thursday (May 15), the U.S. House Committee on Space, Science and Technology convened with scientists to discuss a rather exciting topic: What can NASA do if we identify a dangerous asteroid on a collision course with Earth? It was an especially prudent subject given all the recent fuss about asteroid 2024 YR4, which had a notable chance of hitting our planet before scientists refined its position and deemed it harmless. Most of Thursday's conversation surrounded the agency's highly anticipated Near-Earth Object (NEO) Surveyor mission, which should greatly improve hazardous asteroid detection capabilities as a whole. However, there were also many efforts to address the elephant in the room: the Trump administration's recently announced intention to slash NASA's top-line funding by 24% for the upcoming fiscal year. The proposed cut to the agency's science programs — which includes its planetary defense work — is even deeper, at 47%. Outlined in the White House's "skinny budget proposal," as it's called, the top-line reduction would be the "largest single-year cut to NASA in American history." "If enacted, the Trump administration's skinny budget proposal risks putting NASA on a path to irrelevance," Rep. Valerie Foushee (D-North Carolina) said during the hearing. "It threatens our economic and national security, surrenders U.S. leadership and space to our adversaries, and jeopardizes our competitiveness and standing on the world stage. That's a strategic posture I simply cannot accept." The NEO Surveyor mission is the first space telescope that'll be dedicated to locating asteroids that could threaten Earth, NASA says. It's the agency's next big step in upping the nation's planetary defense game, which was really brought to the forefront for the public in 2022 with the DART mission. DART, which stands for Double Asteroid Redirection Test, sent a spacecraft to smash into an asteroid called Dimorpohos. Dimorphos orbits a larger asteroid, called Didymos. Neither threatened us, to be clear, as this was just a proof-of-concept mission. The goal was to see whether this impact would adjust Dimorphos' trajectory around Didymos; if so, it would suggest that a spacecraft can one day be sent to an actually threatening asteroid to knock it off a potential collision course with Earth. DART worked beautifully, but it could use a little help. NEO Surveyor is more of a prophylactic measure for planetary defense. It'll be the thing that spots the asteroid we may want to smash a future DART craft into. "We do not know of any sizable object that has a significant risk of impacting Earth in the next 100 years — however, there are a lot more to be found," Nicola Fox, the associate administrator for NASA's Science Mission Directorate, said during the hearing. "The mission will improve NASA's ability to discover and then define the sizes and the orbits of the NEOs to understand the hazard they actually pose to us," she added. "Finding those potentially hazardous asteroids remains a top priority for NASA's planetary defense program." One of the most promising aspects of NEO Surveyor is the fact that it'll be able to pinpoint NEOs by way of infrared detection. Infrared wavelengths aren't visible to human eyes and most human technology; they're usually thought of as heat signatures. Firefighters, for instance, can use infrared wavelengths to understand fire distribution in a burning building. This detection strategy should yield a higher target hit rate when compared to traditional methods, which are usually based on whether sunlight reflects off an NEO. In fact, an issue with relying purely on sunlight for NEO hunting was illustrated with the Chelyabinsk asteroid that exploded over Russia in 2013, which damaged many buildings and injured over 1,000 people. "The blast released energy equivalent to about 440 kilotons of TNT, more than 30 times the force of the Hiroshima bomb, shattering windows, injuring thousands and causing millions of dollars in property damage in Russia. Because the asteroid approached from the direction of the sun, it was undetectable by ground-based telescopes and went untracked," Rep. Brian Babin (R-Texas), who currently serves as the chairman of the House Committee on Space, Science and Technology, said during the hearing. Though NEO Surveyor still won't be able to detect a possibly hazardous asteroid coming straight from the direction of the sun, it'll enable observations of NEOs super-close to our star, Fox said. "It'll help us find the objects, including the dark fraction of the population, which we think is sort of roughly 35 to 40% or so of the population," Amy Mainzer, principal investigator for the NEO Surveyor mission and a professor at the University of California, Los Angeles, said during the hearing. "It will also help us measure the sizes, because we can quickly convert the infrared fluxes into a diameter as soon as we get an orbit from the Minor Planet Center … That's such an important component to the impact energy." "We track the orbits of all 38,000 currently known NEOs, including the more than two and a half thousand potentially hazardous ones, and an impact by any one of those would be devastating," Matthew Payne, director of the Minor Planet Center, said during the hearing. Fox said that NEO Surveyor should be ready to launch by 2028, perhaps sooner, but that is of course assuming the mission gets the funding it needs. "Passback documents" — a sort of preview of the White House's 2026 budget request— suggested that the proposed cuts could lead to the closure of NASA's Goddard Space Flight Center in Maryland. The prospect of shutting down such a key agency research facility worries scientists, and it came up during the hearing. Fox was asked, theoretically, what would happen if NASA's Ames Research Center in Silicon Valley, which plays a vital role in planetary defense, were to be shut down. "If [NASA Ames] were no longer able to do the the the assessment, what we would lose is really the ability to give our sort of early expert advice to [the Federal Emergency Management Agency], which is then responsible for deciding where the perimeter is and what the response is to protect as much human life as possible," Fox said. Payne said that, at present, the Minor Planet Center hasn't been affected by the proposed cuts; Mainzer said she's uncertain how the cuts might affect NEO Surveyor's operations. She also emphasized how expensive it can be to train scientists like herself to lead such an important mission. "We really do have to have the investment and the time that it takes to learn the science, to be able to do it well," Mainzer said. Fox echoed the uncertainty, responding to nearly all questions concerning Trump's skinny budget with the answer that she needs to see the finalized budget before coming to conclusions. "We await the full president's budget so we can see the priorities in the direction on which missions may be supported or not supported," she said. "It's clear that planetary defense leverages many of our federal [science and technology] agencies. Now, whether that federal agency continues — whether that expertise continues — I think, is now in question," Rep. Zoe Lofgren (D-California) said during the hearing. Other Trump-instigated orders, like widespread layoffs of probationary employees and deferred resignation programs, are creating a "brain drain," she added. Recent executive orders, for instance, have seen the rapid federal layoffs of over 800 workers at the National Oceanic and Atmospheric Administration (NOAA) who monitor natural disasters such as hurricanes and forecast daily weather patterns. The deferred resignation program is a sort of roundabout way of laying off employees, offering them payment through a certain month if they leave of their own accord. "A very reasonable question is whether NASA should, in fact, be spending more money on asteroid monitoring and defense given the catastrophic risk to our country and civilization," Rep. George Whitesides (D-California), who used to work at NASA in a leadership position, said during the hearing. "As several members have mentioned already, our leadership in this area, like so many areas of space and Earth science, are under threat now from the proposed cuts to NASA's budget, as well as the budgets of other science agencies." "We're talking about impacts that can actually wipe out an entire region, lay waste to a country or devastate the planet. And, you know, this is something that we can do something about. Actually, this is a natural disaster that is 100% preventable if we do our homework," Payne said. Related Stories: — Reshaping our return to the moon: Trump's 2026 budget gives Artemis a major facelift — Trump's 2026 budget plan would cancel NASA's Mars Sample Return mission. Experts say that's a 'major step back' — Trump administration cancels lease for NASA's Goddard Institute for Space Studies lab in New York City Of note, Rep. Foushee asked both Payne and Mainzer how much NEO tracking could improve if artificial intelligence could be implemented in the workflow. Both agreed that training systems with AI would lead to more accurate and more rapid results, but when Foushee inquired how much funding would be necessary to realistically perform such AI implementation, the question was deferred to Fox. "Adequate funding is certainly a major thing," Fox said. Exactly how our planetary defense strategies may be affected hinges on the details of Trump's budget, which have not yet been released. (And Congress still has to enact a budget, which remains a proposal until that happens.) If the White House indeed cuts back on funding for these efforts, Fox said NASA may be able to rely on global partners for hazardous NEO tracking. "If we can't all unite on a large chunk hurtling towards the planet, what are we going to unite on?" Fox said.
Yahoo
26-03-2025
- Science
- Yahoo
Earth 1, asteroids 0: The next generation of planetary defense takes shape at JPL
There is a non-zero chance that somewhere in the nearby solar system is a rock that might kill us all. This stony assassin may well be orbiting the sun at this very moment, careening down a celestial path that could, one day, intersect with ours. And if that rock is big enough and hits in the right place — boom. Fire and smoke and death and extinction. Homo sapiens goes the way of T. rex. To save ourselves from a killer asteroid, first we have to find it. A spacecraft now under construction at NASA's Jet Propulsion Laboratory may be our best hope. The Near-Earth Object (NEO) Surveyor is a $1.4-billion infrared telescope with a single mission: to hunt asteroids and comets that could pose a danger to Earth. Astronomers have already identified roughly 2,500 asteroids larger than 140 meters that could come worryingly close. Statistical models suggest that there could be as many as 25,000 such objects in the solar system, in addition to countless smaller asteroids that could also do considerable damage, said Amy Mainzer, a UCLA professor of planetary science who is leading the NEO Surveyor mission for NASA. 'We still don't know everything that's in our own backyard,' Mainzer said. And if we do need to mount a defense against an incoming threat from space, she said, 'it all starts with knowing that there's something there and having enough time to really make an informed plan.' Asteroids are essentially construction debris left over from the formation of the solar system. A collapsed cloud of gas and dust condensed in places to create planets, including the one we're on right now. It also produced smaller rocks that never achieved planet size or status. The NEO Surveyor fulfills a 2005 act of Congress ordering NASA to catalog 90% of near-Earth objects larger than 459 feet (140 meters), which is roughly the size at which an asteroid could take out a city, or 'vaporize the L.A. basin,' said Tom Hoffman, JPL's project manager for the mission. Within the first five years after its planned Sept. 13, 2027, launch from Cape Canaveral, Fla., the mission is tasked with identifying at least two-thirds of the estimated 25,000 asteroids larger than that size believed to be circling Earth. Within its first decade, astronomers expect to have tracked at least 90%, Mainzer said. Most of what we know about the asteroids in our celestial neighborhood comes from ground-based telescopes. When viewed here on Earth, the most elusive asteroids look like ink spots traveling through a dark sky, Hoffman said. But those dark objects absorb enough energy from the sun to raise their temperature. Through an infrared telescope, they glow like red Christmas lights. The telescope's destination is the first Lagrange point, or L1, one of five known places in the solar system where the balanced gravitational forces of the sun and Earth tend to hold objects in place. From a fixed distance of roughly 1 million miles above Earth — five times the distance from here to the moon — it will follow our planet around the sun, taking in an exponentially broader view of the field around Earth's orbit than existing telescopes do. The more images it captures of a potentially hazardous object, the more accurately astronomers can plot the object's future movements and calculate the risk. The most famous collision between Earth and one of these objects took place 66 million years ago, when a rock 7.5 miles wide smashed into what is now the Yucatan Peninsula. The impact incinerated everything in the vicinity, and sparked massive fires. Toxic clouds of pulverized rock, sulfate aerosols and wildfire soot soon blanketed the planet, blocking all but a tiny fraction of the sun's energy and bringing photosynthesis to a virtual halt for the only known time in history. Much smaller rocks can still wreak havoc. In 2013, an asteroid approximately 60 feet in diameter entered the atmosphere near the city of Chelyabinsk, Russia. It exploded before hitting the ground — a common fate for smaller asteroids that can't withstand the compression of entry — and shattered enough windows to send roughly 1,600 people to the hospital with minor injuries. 'Anything bigger than that — it's not just going to be broken glass,' Mainzer said. Real-life asteroids don't come hurtling toward Earth from the outer reaches of space the way they do in the movies. They tend to orbit elliptical paths around the sun, passing within sight of our telescopes years, decades or even centuries before any potential collision. Technology has, fortunately, come a long way since the late Cretaceous. The sooner we find these asteroids, the more time we have to figure out the right way to prevent a catastrophe, and the less work it takes to successfully pull that off. 'It all comes down to doing things as early as you can, because then you barely have to do anything,' said Kathryn Kumamoto, head of the planetary defense program at Lawrence Livermore National Laboratory. 'If we did want to, say, deflect the asteroid, we only have to nudge it a very little bit if we can get to it very far in advance,' Kumamoto said. 'A change of a millimeter per second over decades will add up to thousands of kilometers, and that can be enough to make the asteroid miss the Earth entirely.' NASA's Double Asteroid Redirection Test, or DART, confirmed in 2022 that it's possible to successfully change the trajectory of a near-Earth object when it deliberately crashed a spacecraft into a tiny asteroid 7 million miles away. But brute force isn't our only option. Other proposals include painting part of the object with a light-colored coating that would redistribute its heat and eventually change its spin and orbit, Mainzer said, or parking a large spacecraft nearby whose gravity would reshape the object's trajectory. 'It all starts with knowing that there's something there and having enough time to really make an informed plan,' Mainzer said. This story originally appeared in Los Angeles Times.
Yahoo
25-02-2025
- Science
- Yahoo
NASA Awards SpaceX $100 Million Contract To Launch Asteroid Hunting Telescope
Remember just last week when we were all excitedly reading about the record one in 32 chance that a giant asteroid was on a collision course with Earth? Well, it isn't anymore but that doesn't mean there aren't more massive space rocks up there that could smash into the planet without much notice. To prepare for this, NASA awarded SpaceX a $100 million contract to launch a new satellite that could monitor extraterrestrial threats to the Earth. NASA began developing a special telescope that can scan the night sky for asteroids almost five years ago. The craft, called the Near-Earth Object (NEO) Surveyor, comprises an infrared telescope that will search space for potentially threatening asteroids, reports Production of the specially-designed satellite kicked off in January 2023 and NASA is now preparing to set out a plan to launch the Surveyor into space to start work protecting the planet. The task of transporting the craft into orbit will now fall on Elon Musk-backed SpaceX, as reports: The agency announced on Friday (Feb. 21) that it has selected Elon Musk's company to launch its NEO Surveyor spacecraft, which will hunt for asteroids and comets that could pose a threat to Earth. NEO Surveyor will lift off atop a Falcon 9 rocket from Florida's Space Coast no earlier than September 2027. The total value of the newly announced firm, fixed-price contract is about $100 million, which covers the launch and related services, NASA officials said. SpaceX will transport the Surveyor to a point about 930,000 miles away from Earth. From there, it will scan space using telescopes that can pick up two infrared wavelengths to spot threatening asteroids. Read more: Even SpaceX Would Apparently Rather Use A Ford F-150 Lightning Than Tesla Cybertruck NASA awarded the $100 million contract to SpaceX to cover the launch of the craft, but not its construction or operation. The costs of designing, developing and assembling the probe fall on NASA, which is already knee-deep in the production of the new telescope. SpaceX will just be tasked with getting the probe to its destination onboard one of the company's Falcon 9 rockets. The rocket will launch "no earlier" than September 2027, reports NASA and there isn't yet a timeline on how long it will take for the probe to begin scanning for threats once it's in space. Musk's private space company regularly works with NASA, providing rockets to launch all kinds of tech into orbit when the American space agency requires. NASA previously called on SpaceX to run supply missions to the International Space Station and the company could even be tasked with transporting a new lunar rover to the surface of the moon one day. Once deployed to a site that scientists call the Sun-Earth Lagrange Point 1, NEO Surveyor will form part of our planetary defense system to scan for asteroids that are at least 460 feet across, explains. The program launched in 2021, but its importance was highlighted over the past few weeks when the world watched to see if a city-killing asteroid would hit Earth. The new probe aims to give advanced warnings of similarly enormous space rocks, and will also help scientists map the paths of such asteroids to see if they could hit our home. The program remains an important one, despite it emerging that the near-Earth object, designated 2024 YR4, probably won't hit Earth in 2032 after all, reports Ars Technica. To hunt out future risks to our planet, the NEO Surveyor will work alongside probes like the Nancy Grace Roman Space Telescope, which will also launch in 2027, and the Large Synoptic Survey Telescope, which is currently under construction in Chile. Now, NASA will just have to hope that the team responsible for delivering the NEO Surveyor isn't gutted as part of Musk's never-ending cuts to the U.S. Government. At least the fact that SpaceX will make $100 million off the back of the project should mean that it's safe for now. Read the original article on Jalopnik.
Broadcast Pro
25-02-2025
- Science
- Broadcast Pro
NASA selects SpaceX to launch NEO Surveyor mission
NEO Surveyor will launch on a Falcon 9 from Florida as soon as September 2027. NASA has awarded SpaceX a contract to provide launch services for the Near-Earth Object (NEO) Surveyor mission, a space telescope designed to detect and track asteroids and comets that could pose a threat to Earth. The mission is set to launch no earlier than September 2027 aboard a SpaceX Falcon 9 rocket from Florida. The contract, valued at approximately $100m, falls under NASAs Launch Services II agreement and covers all mission-related costs. NEO Surveyor will carry a nearly 20-inch (50 cm) infrared telescope capable of detecting both bright and dark asteroidsespecially those difficult to identify with current observation methods. The mission aims to advance NASAs planetary defence strategy by identifying and studying potentially hazardous near-Earth objects (NEOs) within 30m miles of Earth's orbit. Over a five-year survey, the mission seeks to locate at least two-thirds of undiscovered NEOs larger than 140 meters (460 ft), which are large enough to cause significant regional damage if they were to impact Earth. By utilising infrared imaging, the telescope will provide precise measurements of asteroid sizes, compositions, shapes, rotation patterns, and orbits. The mission is managed by NASAs Planetary Science Division and the Planetary Defense Coordination Office, with programme oversight from NASAs Marshall Space Flight Center. NASAs Jet Propulsion Laboratory (JPL) is leading development, with contributions from various aerospace and research organizations, including BAE Systems SMS, Space Dynamics Laboratory and Teledyne. The University of Colorado Boulder will oversee operations, while Caltechs Infrared Processing and Analysis Center will manage survey data. NASAs Launch Services Programme at Kennedy Space Center will oversee the launch, marking another significant step in the agencys efforts to enhance planetary defence and mitigate potential asteroid impact risks. Tags: NASASpaceXFalcon 9NEO SurveyorNEO Surveyor missionEarth's orbit
The Independent
13-02-2025
- Science
- The Independent
How to stop an asteroid hitting Earth: Would people co-operate to face a global peril?
There have been a few near misses over the years, but what would we do in the event of an actual meteor strike? Earlier this year, while war and chaos continued to unfold further east, scientists gathered on the outskirts of Rome to discuss another sort of catastrophe. Astronomers and physicists from some of the world's top institutions grappled with a dire scenario: an asteroid up to 1,300ft in diameter – big enough to cause epochal damage – was hurtling towards Earth, and the countries likely to be hit included some of the poorest and most unstable in the world. Policymakers bickered over whether to try to blow it up or move it, and nations nearly went to war over whether deflecting it would make the fiery rock more likely to land on them… Relax. It was only a drill. Had it been a real emergency, you would have been instructed to kiss the world – or a large chunk of it – goodbye. Watching this five-day asteroid war game from the wings were two Americans, one from the scientific world and one from the military. These elder statesmen of what's called planetary defence have been responsible for reminding policymakers that the planet and all life on it have been shaped by big rocks from outer space slamming into it. Dave Morrison was one of the first researchers to suggest that, unlike the dinosaurs made extinct by an asteroid impact, we might be able to defend ourselves. Former US Air Force Lieutenant Colonel Lindley Johnson was eventually put in charge of Nasa 's Near-Earth Object (NEO) division after first suggesting in the 1990s that the Air Force track asteroids. These men, along with all the world's dedicated planetary defenders, are proud (and relieved) that the Big Question has evolved from what if a cataclysm-inducing space rock is aiming for us – we now know an impact is inevitable – to what will we do about it. That question was the main topic of that mid-April meeting held in a conference hall in Rome. The European Space Agency had invited astronomers, physicists, nuclear engineers and mathematicians to discuss the slim possibility of a space rock smashing into Earth and causing regional damage or maybe even the end of civilization. Scientists today can tell us, with various degrees of certainty, that an object will smash into the planet in, say, 200 years, and they believe we can probably stop it. But nobody knows how people could or would cooperate to face a global peril – and in an age when many politicians deny climate change, can we even count on them to believe the hazard is real? Morrison was, in 1989, one of the first scientists to warn the public about asteroids, with Cosmic Catastrophes, a book he co-wrote with astronomer Clark Chapman. Since then, the field has grown to include national space agencies, the US Congress, the United Nations and labs filled with specialists. Thanks to their efforts, more than 150,000 asteroids are now registered with the Smithsonian's Minor Planet Center. However, the defenders estimate there are tens to hundreds of thousands more out there that we cannot see, many hidden by the sun. Meanwhile, about 12,700 of those identified are categorised as NEOs, with orbits that come within 121 million miles of the sun, of which about 1,000 NEOs are civilisation-enders – larger than a half mile in diameter. None of the behemoths seems to be a likely threat, but about 1,600 other mapped NEOs may be headed our way, and an impact could kill millions. Asteroid impact was first identified by the late geologist Gene Shoemaker when he was examining lunar craters in the 1950s for the US space programme. Eventually, with another scientist called Edward Chao, he discovered coesite, a type of silica produced in a violent impact. But his most important find – in terms of planetary defence – was Comet Shoemaker-Levy 9, which smashed into Jupiter in 1994. It was the first extra-terrestrial impact human beings had predicted and then observed in real time. This gave scientists confidence that similar calculations could be made for Earth. Around the same time that Shoemaker was compiling his notes on coesite, geologist Walter Alvarez discovered a layer of iridium-infused clay at the geological strata separating the era of the dinosaurs and our epoch – and iridium is extremely rare on Earth but common in meteorites. Geologists soon found a similar iridium layer at the same geological strata in other parts of the world and postulated that a catastrophic impact had occurred around the time the dinosaurs became extinct. (Scientists even know where – just off the Yucatan Peninsula, at Chicxulub). In the decades since, they have learned more about how extra-terrestrial impacts have changed our planet. They believe our moon is the result of a collision between two planets the size of Mars and Venus. And numerous smaller objects, with diameters in the five to 10-mile range (like the one that caused the dinosaur extinction) have also slammed into the planet. When Chapman and Morrison published their 1989 book about cosmic catastrophes, they covered a broad range of menacing events, including comets, asteroids and supernovas. But both men thought the asteroid impact scenario was the most intriguing because mankind could theoretically do something to prevent one. In 1990, US congressional staffers invited Morrison to present his findings on space rock hazards. A year later, Congress authorised Nasa to study asteroids and how to deflect them. Chapman and Morrison gathered together a team, which concluded that the most dangerous asteroids were about one mile in diameter. Such a rock could have civilisation-ending effects, mainly because weather alterations would result in the starvation of billions of people. So they recommended sky surveys to find all objects of that size. Meanwhile, the planetary defender "community" was attracting nuclear weapons designers, about to be left unemployed by the end of the Cold War, who argued that their technology could save us from an asteroid. And on 24 December 2004, they captured the world's attention with an alarming calculation: it turned out an 885ft-diameter hunk of dark space rock was heading our way, with a one in 25 chance of smashing into Earth in 2036. The ominous spinning rock was soon named "Apophis", after an Egyptian god, "the Uncreator". And while the experts at the Jet Propulsion Laboratory (JPL) in Pasadena, California – which tracks NEO orbits – soon refined the prediction down to a much less threatening one in 250,000, that still means Apophis will pass between us and our satellites and be visible to the naked eye. Canadian-born astronomer Paul Chodas manages Nasa's NEO office at the JPL. There, he feeds an asteroid's many variables – spin, mass, the way it reflects and absorbs light and radiates heat, and the gravitational pull of other asteroids nearby – into a supercomputer that spits out an orbit prediction (filled with variables that sometimes involve plus or minus 18 million miles). One October morning in 2008, his mobile rang as he was dropping off his son at school. It was the Minor Planet Center at Harvard, reporting that an object was speeding towards Earth. Chodas plugged the coordinates into his computer and was soon able to predict an impact time and location – just 20 hours hence, in the Middle East. The JPL then contacted Nasa, who called the White House – because Johnson at Nasa was especially concerned that governments in the volatile region be notified. "For a while, we had predicted it heading towards Mecca," he says, drily. "And that was a concern." At the JPL, Chodas and his colleague, Steve Chesley, drilled into the numbers and soon had a precise impact point, near a fly-specked outpost, population 10 people, deep in the Sudanese desert. JPL scientists were able to direct a team of university students from Khartoum there – and even Chodas was surprised when they found remnants right where his equations had led them to look. Still, frightening uncertainties remain. The last significant asteroid event was one that nobody saw coming. In 2013, a bus-sized space rock blew up in the sky near the town of Chelyabinsk, Siberia, with a force similar to a nuclear bomb. Windows were blasted, and one thousand people went to hospital. Because many drivers in Russia mount video cameras on their dashboards, scientists had a plethora of YouTube images of a streaking light, followed by a blinding explosion in the sky, which they used to pinpoint the object's trajectory. Chelyabinsk gave them another lesson: what even a relatively small asteroid, bursting not on impact but in the air, can do. And they know it's only a matter of time before something like that happens over New York, London, Delhi or Tokyo. Between "Apophis" and Chelyabinsk, a US law in 2005 instructed Nasa to detect, track, catalogue and characterise the physical characteristics of asteroids larger than about 460ft across. In other words, to do what Morrison had suggested 15 years earlier: try and find them all. The mapping program involved three main elements – telescopes in Arizona and Hawaii, and a fairly small, space-based telescope operating at infrared wavelengths. And by late 2011, it was announced that Earth is – for now – not a target for any huge, civilisation-ending mass. But hundreds of thousands of unmapped smaller objects are winging around nearby: apparently, only one per cent of NEOs above 60ft in diameter have been mapped – and because they're harder to find, they're more likely to hit us. Objects as small as 450ft across would cause severe regional damage, and the mapping project has identified only an estimated quarter of them. Geologists believe objects between about 150 and 450ft in diameter hit Earth every 100 to 300 years, and some have wreaked havoc. Nasa is considering a proposal to build a new space-based telescope that will find and measure many more asteroids; and if approved, it could be operational by 2020. Deflecting an asteroid is an embryonic science. There are three schemes, roughly classified as Nuke, Kick or Tug. The Nuke option would aim an explosive device or, more likely, many – at an asteroid on a collision course. Despite its Hollywood-grade visual potential, the planetary defence community regards it as a last-ditch effort. The other two options are the Kick (aiming a "kinetic impactor" at an asteroid to knock it slightly off orbit) and the Tug (shooting an unmanned spacecraft into the orbit of the asteroid to operate as a "gravity tractor" with enough mass to pull the rock off its trajectory). While all three schemes depend on man's ability to navigate a craft to an asteroid – achieved when the Rosetta craft landed the Philae probe on a comet last November – none of the asteroid mitigation techniques has been tested. However, Nasa hopes to demonstrate the Tug method as part of a 2020 mission, which would launch a robotic spacecraft to break off and grab a chunk of an asteroid. The craft and its cargo will remain in the asteroid's orbit for 100 days, and scientists believe its enhanced mass will eventually pull it off-course. The device would then drag the asteroid chunk back to the moon's orbit and leave it there, allowing future experiments on it. The idea of giving the moon a satellite still sounds like science fiction, but planetary defenders want nations and space agencies to put real money behind testing it; and for policymakers, journalists and scientists to discuss the threat calmly and realistically, somewhere between the poles of mass panic and dubious hilarity. The public will be hearing with increasing frequency about objects veering relatively close or even speeding toward us – particularly today, when a motley crew of astronomers, physicists, rock stars and filmmakers get behind the world's first "Asteroid Day". The date was selected because on 30 June 1908, an asteroid flattened thousands of square miles of remote Siberian forest, in what's known as "The Tunguska Event". The organisers and participants include Brian May, the Queen guitarist and astrophysicist, and Lord Martin Rees, the Astronomer Royal; events are planned in cities around the world; and live presentations will be beamed from London and San Francisco. The Asteroid Day organisers are also circulating an online petition called "The 100X Declaration" calling for a hundredfold increase in the mapping and tracking of asteroids. Meanwhile, after eight years of deliberating, in March the UN finally announced the creation of a global early-warning system to protect the planet from a potentially city-destroying, tsunami-causing or, worse, civilisation-ending large space object. And in mid-April the planetary defenders tested the concept in Frascati. Their mission: save the planet from an asteroid possibly four times the size of a football field. The scenarios were so realistic that their press releases had to be emblazoned with bright red boxes proclaiming, "Exercise. Exercise. Not a Real World Event." At the beginning of the game, participants learned that an asteroid, estimated to be somewhere between 460 and 1,300ft in diameter, was apparently on course to smash into Earth on 3 September 2022. They divided into three groups – national and international policymakers, the media and scientists – and played out over five days what humans might do. In the first year after the asteroid's discovery (days one and two), the participants heard that scientists had estimated a long "risk corridor" from south-east Asia to Turkey. As the asteroid moved through its orbit, the experts refined their predictions, homed in on its size and likely damage point, and advised policymakers on the options. By August 2019 (day four), the participants learnt global policymakers had agreed to fire six kinetic impactors, and they reached their target six months later. However, a debris cloud then prevented participants from knowing what had worked until January 2021 (day five), when it was announced that two of the six KIs had missed, one had hit and fractured the asteroid, and another had broken off a chunk that remained on a path towards Earth but was hidden from view by sunlight. Two others hit the remains of the now-broken asteroid, deflecting the largest piece of it. The following year (later on day five), the participants learnt that the broken fragment was still hurtling toward Earth and remained a significant hazard. It would arrive on time, somewhere in India, Bangladesh or Myanmar. And about a "month" before its impact, scientists were able to pinpoint the object's size (about 261ft in diameter), as well as the likely time (9am) and precise location (Dhaka, Bangladesh, population 15 million). They predicted that the explosion would release 18 megatons of energy: similar to that explosion in 1908 that flattened thousands of miles of Siberian forest. Chodas says: "The number one lesson I took away is that we need infrared, in-space telescopes to tell us more about the sizes of these objects." Johnson says that the exercise proved that humans can mount an asteroid response – and it can be affordable, a key element when trying to prevent disasters that might not occur in our lifetimes. ("A few hundred experts and a few hundred million dollars per year," he says.) The astronaut Russell "Rusty" Schweickart says: "I fear there's not enough of a collective survival instinct to really overcome the centrifugal political forces. That is, in a nutshell, the reason we'll get hit…" But the exercise ended on a cliffhanger, with a massive, flaming rock closing in on a teeming, impoverished Asian city. Having done the best they could, the planetary defenders hung up their hero lanyards, packed their suitcases, checked out of their hotels and headed for the airport, leaving the planet forewarned.
