Category Archives: Planetary Collisions

Deflecting Killer Asteroids Away From Earth

Deflecting Killer Asteroids Away From Earth: How We Could Do It | Asteroid 2005 YU55, Asteroids & Near-Earth Objects | Asteroid Impact & Mass Extinction | Space.com.

An illustration of how solar sails might help deflect the asteroid Apophis.
CREDIT: Olivier Boisard

A huge asteroid’s close approach to Earth tomorrow (Nov. 8) reinforces that we live in a cosmic shooting gallery, and we can’t just sit around waiting to get hit again, experts say.

Asteroid 2005 YU55, which is the size of an aircraft carrier, will zip within the moon’s orbit tomorrow, but it poses no danger of hitting us for the foreseeable future. Eventually, however, one of its big space rock cousins will barrel straight toward Earth, as asteroids have done millions of times throughout our planet’s history.

If we want to avoid going the way of the dinosaurs, which were wiped out by an asteroid strike 65 million years ago, we’re going to have to deflect a killer space rock someday, researchers say. Fortunately, we know how to do it.

“We have the capability — physically, technically — to protect the Earth from asteroid impacts,” said former astronaut Rusty Schweickart, chairman of the B612 Foundation, a group dedicated to predicting and preventing catastrophic asteroid strikes. “We are now able to very slightly and subtly reshape the solar system in order to enhance human survival.”

 

In fact, we have several different techniques at our disposal to nudge killer asteroids away from Earth. Here’s a brief rundown of the possible arrows in our planetary defense quiver. [The 7 Strangest Asteroids in the Solar System ]

 

The gravity tractor

If researchers detect a potentially dangerous space rock in plenty of time, the best option may be to send a robotic probe out to rendezvous and ride along with it.

The spacecraft’s modest gravity would exert a tug on the asteroid as the two cruise through space together. Over months or years, this “gravity tractor” method would pull the asteroid into a different, more benign orbit.

“You can get a very precise change in the orbit for the final part of the deflection using a technology of this kind,” Schweickart said in late September, during a presentation at Caltech in Pasadena, Calif., called “Moving an Asteroid.”

Humanity has already demonstrated the know-how to pull off such a mission. Multiple probes have met up with faraway asteroids in deep space, including NASA’s Dawn spacecraft, which is currently orbiting the huge space rock Vesta.

And in 2005, the Japanese Hayabusa probe even plucked some pieces off the asteroid Itokawa, sending them back to Earth for analysis.

Smash ’em up

We could also be more aggressive with our asteroid rendezvous craft, relying on brute force rather than a gentle gravitational tug. That is, we could simply slam a robotic probe into the threatening space rock to change its orbit.

We know how to do this, too. In 2005, for example, NASA sent an impactor barreling into the comet Tempel 1 to determine the icy object’s composition.

The impactor approach would not be as precise as the gravity tractor technique, Schweickart said, but it could still do the job.

There’s also the possibility of blowing the asteroid to smithereens with a nuclear weapon. The nuclear option could come into play if the dangerous space rock is too big to knock around with a kinetic impactor,  but it would likely be a weapon of last resort.

For one thing, blasting an asteroid to bits might end up doing more harm than good, said fellow presentation panelist Bill Nye, executive director of the Planetary Society.

“Momentum is conserved,” Nye said. “If you blow it up, then the whole giant spray of rocks is coming at the Earth instead of one.”

The politics involved in mobilizing use of a nuke could also be a cause for concern, Schweickart said. It will likely be hard enough to convince the world to mount any sort of asteroid-deflection mission in time, and adding nuclear missiles to the equation would make things much stickier.

“The potential use of nuclear explosives for deflection cannot currently be ruled out,” Schweickart said. “But it is an extremely low probability that they will be needed.”

Close Encounters of the Comet Kind: A Brief History
This image of Comet Tempel 1 was taken by NASA’s Deep Impact spacecraft on July 4, 2005, 67 seconds after a probe crashed into the comet.
CREDIT: NASA/JPL-Caltech/UMD

‘Mirror bees’ and foil wrap

While we’re pretty sure that gravity tractors and kinetic impactor probes would work, researchers are also looking into several other ideas. [Photos: Asteroids in Deep Space]

There’s the “mirror bee” concept, for example, which would launch a swarm of small, mirror-bearing spacecraft to a dangerous asteroid. These mini-probes would aim reflected sunlight at one spot on the space rock, heating it up so much that rock is vaporized, creating propulsive jets.

“The reaction of that gas or material being ejected from the asteroid would nudge it off-course,” Nye said.

The Planetary Society is helping fund research into mirror bees, Nye said. And while he said the concept isn’t yet ready for deployment or demonstration, he stressed that it’s not too far off, either.

“Maybe five years,” Nye told SPACE.com. “It’s not 30 years.”

Nye also floated another, more speculative idea. It might be possible to move an asteroid, he said, by wrapping it in reflective foil, like a giant baked potato. Photons from the sun might then nudge the space rock away from Earth, in much the same way they propel spacecraft equipped with solar sails.

“This might work, even if the thing is rotating,” Nye said. “OK, make no promises. But it’s something to invest in.”

Passing the intelligent life test

The biggest key to deflecting dangerous asteroids, researchers say, is detecting them with plenty of lead time to take appropriate action. We’d like to have a least a decade of notice, NASA scientists have said.

It’ll take awhile, after all, to mobilize and launch a deflection mission, and for that mission to do its job, especially if we go the gravity tractor route.

We need to make sure we can rise to the challenge when a big, threatening asteroid shows up on our radar, Schweickart and Nye said. Civilization’s very survival depends on it.

“If there is a community of intelligent life out in the universe … those intelligent beings will have already conquered this challenge,” Schweickart said. “Our entrance exam to that community of intelligent life is to pass this test.”

You can follow SPACE.com senior writer Mike Wall on Twitter: @michaeldwall. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

Big Asteroid to Cross Earth-Moon Orbit Tuesday 11/8/11

Big Asteroid to Cross Earth-Moon Orbit Tuesday | Wired Science | Wired.com.

    By Mark Brown, Wired UK

    An asteroid the size of an aircraft carrier is to soar past the Earth this week and, while NASA is certain that the space rock will not hit us, it will be our closest encounter with such a large chunk of rock in three decades.

    The 400-yard-wide asteroid is called 2005 YU55and at the point of closest approach it will graze our planet at 201,700 miles — about 10 percent closer to Earth than the Moon’s typical orbit.It is the “closest approach by an asteroid, that large, that we’ve known about in advance,” said principal investigator Lance Benner, from NASA’s Jet Propulsion Laboratory, in an educational announcement. This gives the space agency an unprecedented view of such a rare flyby — and it will take full advantage.

     

    NASA will track 2005 YU55 from the Deep Space Network at Goldstone California, and provide radar observations from the Arecibo Planetary Radar Facility in Puerto Rico. This should reveal a wealth of detail about the asteroid’s surface features, shape, and dimensions.

    The Arecibo radar telescope spotted the asteroid back in April 2010, and those observations provided the ghostly image of YU55, above. NASA hopes to get higher resolution snaps — with details as fine as two meters per pixel — this month.

    But what about amateur astronomers, will they be able to see it? “Absolutely,” said NASA astronomer and YU55 investigator Marina Brozovic in the announcement. “8 November is when it becomes a nighttime object and that is when you can see it.”

    “400 meters, I’d say, is a moderate size asteroid, but it’s still small and very far away. You’ll need at least a six-inch telescope in order to be able to observe it. You’ll see it buzzing really fast along the sky,” said Brozovic.

    “The pass’ track is especially favorable for western Europe and North America. But you’ll need to know exactly where and when to look,” wrote Kelly Beatty, senior contributing editor of Sky and Telescope magazine.

    The when is 23:28 UK time on 8 November. As for the where, Beatty wrote that, “the object will traverse the 70 degrees of sky eastward from Aquila to central Pegasus in just 10 hours, clipping along at seven arcseconds per second.” A star chart is available here.

    2005 YU55 is trapped in an orbit that frequently brings it back to Earth and our nearby neighboring planets — but the 2011 encounter with Earth is the closest this space rock has come for at least the last 200 years. NASA is certain that it will miss us, and “the gravitational influence of the asteroid will have no detectable effect on anything here on Earth, including our planet’s tides or tectonic plates.”

    Plus, “we have a very good idea about its orbit for the following hundred years and there is no chance of impact,” said Brozovic in the announcement. “We believe with these upcoming measurements at Arecibo and Goldstone we will remove this threat even further — probably for many centuries.”

    Updated: Nov. 7, 2011; 12:40 p.m. EST

    Image: NASA/Cornell/Arecibo/JPL-Caltech

    Asteroid Yu55 on course for close encounter with Earth

    Asteroid Yu55

    An image of asteroid Yu55, made from radar data taken in April 2010. Photograph: AP

    Astronomers around the world have readied their telescopes to catch a glimpse of a speeding ball of rock that will hurtle past the Earth on Tuesday night.

    Scientists say the asteroid, which is about a quarter of a mile wide, will pass inside the moon’s orbit and come within 198,000 miles (319,000km) of Earth at 23.28GMT. This is the closest a tracked object this size has come to the planet.

    Nasa calculates the 400-metre (1,312ft) wide asteroid, known as 2005 YU55, has roughly a one in 10m chance of hitting Earth in the next century. Were it to strike, the collision would unleash the equivalent of several thousand megatonnes of TNT.

    Even with clear skies the asteroid will not be visible to the naked eye, but professional and amateur astronomers will turn their telescopes on the rock to learn about its surface and chemical composition.

    Because the asteroid is approaching from the sun’s direction, there will be too much glare to observe the rock with optical or infra-red telescopes until the day of closest approach.

    “Most of the asteroids we see are so far out that we only get a small amount of information from the light reflected off them,” said Kevin Yates, at the Near Earth Objects Information Centre at the National Space Centre in Leicester. “Because this one is coming in so close we’ll be able to get more radar observations, which will give us a detailed surface map, and be able to get more of a chemical signature on the minerals it’s made up from.”

    The Arecibo telescope in Puerto Rico last year revealed the asteroid to be remarkably spherical while its surface is very dark, suggesting it is rich in carbon.

    Observatories at Nasa’s Goldstone Deep Space Communications Complex, in the Mojave desert of California, and at Green Bank, West Virginia, will join forces with Arecibo to watch the asteroid pass this week. Operators have called on scores of amateur astronomers to help with observations, using 10-12in telescopes with special filters.

    A similar flyby will not happen until 2028 when asteroid 2001 WN5 swings past the Earth at a distance of 143,000 miles.

    “We are finding a whole variety of unusual shapes out there and this asteroid is particularly spherical. If we can characterise them more and understand them more, then if we ever do have a threat from one, understanding the structure and the materials they’re made from would better equip us to divert one. It may be that there are materials on board that could be used as a fuel to drive an engine that would push it into a different orbit over 20 years,” Yates added.

    The asteroid is among the most ancient objects in the solar system, having formed from the dust and gas disc that surrounded the sun 4.5bn years ago. Though born in the asteroid belt between Mars and Jupiter the rock was pulled by gravity or nudged by collisions on to its new orbital course.

    “These are the building blocks left over from when the solar system formed and this particular carbonaceous asteroid is one of the most primitive types,” Yates said. “Understanding its chemical composition is like looking into the ingredients book to see how it was put together.”

    The asteroid will pass close to Venus in 2029, which will disturb its orbit to mean its next passage past Earth, in 2041, could be between 198,000 miles and nearly 30m miles from the planet. The close encounter after that will be with Mars in 2072.

     

     

    NASA finds 90 percent of largest near-Earth asteroids

    NASA finds 90 percent of largest near-Earth asteroids; finds fewer medium-sized asteroids – The Washington Post.

    LOS ANGELES — If you’re worried about a killer asteroid wiping out Earth, NASA has some good news.

    The space agency said Thursday it has identified more than 90 percent of giant near-Earth asteroids, including ones as big as the one thought to have killed the dinosaurs eons ago. None poses a danger to the planet in the next several centuries.

    Comments

    (no/Associated Press) – In this undated artist’s rendition released Thursday Sept. 29,2011 by NASA/Jet Propulsion Laboratory, showing WISE, (Wide-field Infrared Survey Explorer), NASA on Thursday Sept. 29,2011 said its sky-mapping spacecraft called WISE has discovered 911 of 981 of the largest asteroids and has found more than 90 percent of the biggest asteroids that might pose a threat to Earth.

    “We know now where most of them are and where most of them are going. That really has reduced our risk” of an impact, said Amy Mainzer of the NASA Jet Propulsion Laboratory.

    NASA researchers also downgraded their estimate of the number of medium-sized asteroids, saying there are 44 percent fewer than previously believed. The downside is that scientists have yet to find many of these mid-sized asteroids, which could destroy a metropolitan city.

    “Fewer does not mean none,” Mainzer said. “There are still tens of thousands out there that are left to find.”

    The updated census comes from data from NASA’s sky-mapping spacecraft named Wide-field Infrared Survey Explorer, or WISE, which launched in 2009 to seek out near-Earth objects, galaxies, stars and other cosmic targets.

    Unlike previous sky surveys, WISE has sensitive instruments that can pick out both dark and light objects, allowing it to get the most accurate count yet of near-Earth asteroids. The spacecraft takes a small sample of asteroids of varying sizes and then estimates how large the population would be.

    For the largest asteroids — bigger than 3,300 feet across — NASA said 911 of the 981 thought to exist have been found. None poses a threat to Earth in the near future, the space agency said.

    Previous estimates put the number of medium-sized asteroids at 35,000, but WISE data indicate there are about 19,500 between 330 and 3,300 feet wide. Only about 5,200 have been found and scientists said there is still a lot of work left to identify the potentially hazardous ones.

    Results were published in the Astrophysical Journal.

    WISE is not equipped to detect the more than a million smallest asteroids that could cause damage if they impact Earth. The spacecraft recently ran out of coolant and is currently in hibernation.

    By locating most of the giant asteroids, NASA has fulfilled a goal set by Congress in 1998. More recently, the space agency has been asked to find 90 percent of asteroids that are at least 460 feet in diameter — slightly smaller than the Superdome in New Orleans — by 2020.

    Don Yeomans, who heads NASA’s Near-Earth Object Program Office, said that goal is about 35 percent complete.

    NASA satellite to Crash to Earth Today

    Heads up! NASA satellite descends toward fiery doom | The Space Shot – CNET News.

    NASA’s decommissioned Upper Atmosphere Research Satellite, out of gas and out of control, is not descending toward re-entry as rapidly as expected, officials say, likely delaying the satellite’s kamikaze plunge to Earth by a few hours, to late Friday or early Saturday.

    Experts expect more than two dozen chunks of debris to survive re-entry and hit the ground in a 500-mile-long footprint somewhere along the satellite’s orbital track. But given the bus-size 6.3-ton’s satellite’s trajectory and the vast areas of ocean and sparsely populated areas UARS passes over, experts say it is unlikely any falling debris will result in injuries or significant property damage.

    Additional radar tracking is required to pinpoint when–and where–the satellite will make its final descent.

     

    A chart showing the latest predicted entry point for the Upper Atmosphere Research Satellite, based on data from U.S. Strategic Command. Because of uncertainty about the satellite’s behavior as it approaches the discernible atmosphere, the timing of the re-entry could change by several hours either way.

    (Credit: William Harwood/MacDoppler Pro)

    “As of 10:30 a.m. EDT on Sept. 23, 2011, the orbit of UARS was 100 miles by 105 miles (160 km by 170 km),” NASA said in a brief update. “Re-entry is expected late Friday, Sept. 23, or early Saturday, Sept. 24, Eastern Daylight Time. Solar activity is no longer the major factor in the satellite’s rate of descent. The satellite’s orientation or configuration apparently has changed, and that is now slowing its descent.

    Related story
    Track NASA’s crashing satellite to avoid getting hit by space junk

    “There is a low probability any debris that survives re-entry will land in the United States, but the possibility cannot be discounted because of this changing rate of descent. It is still too early to predict the time and location of re-entry with any certainty, but predictions will become more refined in the next 12 to 18 hours.”

    A subsequent update from U.S. Strategic Command, which operates a global radar network used to monitor more than 20,000 objects in low-Earth orbit, predicted the satellite would re-enter sometime around 11:34 p.m. EDT Friday as the spacecraft flies over the southern Indian Ocean. But the prediction was uncertain by several hours and at orbital velocities of 5 miles per second, just 10-minutes of uncertainty translates into 3,000 miles of uncertainty in position.

    For comparison, some 42.5 tons of wreckage from the shuttle Columbia hit the ground in a footprint stretching from central Texas to Louisiana when the orbiter broke apart during re-entry in 2003. No one on the ground was injured and no significant property damage was reported.

    Tracking data is expected to improve as the day wears on, and subsequent updates should be more precise.

    The centerpiece of a $750 million mission, the Upper Atmosphere Research satellite was launched from the shuttle Discovery in September 1991. The solar-powered satellite studied a wide variety of atmospheric phenomena, including the depletion of Earth’s ozone layer 15 to 30 miles up.

    The long-lived satellite was decommissioned in 2005 and one side of its orbit was lowered using the last of its fuel to hasten re-entry and minimize the chances of orbital collisions that could produce even more orbital debris. No more fuel is available for maneuvering and the satellite’s re-entry will be “uncontrolled.”

    Nick Johnson, chief scientist with NASA’s Orbital Debris Program at the Johnson Space Center in Houston, told reporters last week he expects most of the satellite to burn up as it slams into the dense lower atmosphere at more than 17,000 mph. But computer software used to analyze possible re-entry outcomes predicts 26 pieces of debris will survive to impact the surface in a 500-mile-long down-range footprint.

    “We looked at those 26 pieces and how big they are and we’ve looked at the fact they can hit anywhere in the world between 57 north and 57 south and we looked at what the population density of the world is,” he said. “Numerically, it comes out to a chance of 1-in-3,200 that one person anywhere in the world might be struck by a piece of debris. Those are obviously very, very low odds that anybody’s going to be impacted by this debris.”

    For comparison, some 42.5 tons of wreckage from the shuttle Columbia hit the ground in a footprint stretching from central Texas to Louisiana when the orbiter broke apart during re-entry in 2003. No one on the ground was injured and no significant property damage was reported.

    'Dinosaur Killer' Asteroid Parent Now Doubted

    Was the ‘Dinosaur Killer’ Unfairly Charged? – ScienceNOW.

     

     

    Wanting to bring the master evildoer, not just a henchman, to justice is human enough. So when planetary scientists traced the asteroid that wiped out the dinosaurs 65 million years ago back to a rampaging rock named Baptistina in the asteroid belt there was palpable satisfaction that the ultimate culprit seemed to have been nailed.

    But now a group of astronomers is challenging that claim. Baptistina did blast another asteroid to smithereens, sending a devastating shower of debris into the inner solar system, but that cataclysmic collision probably came too late to have sent the dino killer to Earth, they argue.

    The original CSI-like case against Baptistina involved an odd link between an asteroid’s size and the ability of sunlight to move it across the asteroid belt. In their 2007 Nature paper, planetary scientists William Bottke, David Vokrouhlický, and David Nesvorný of the Southwest Research Institute (SwRI) in Boulder, Colorado, identified asteroids whose similar orbits mean they are members of the “family” of asteroids formed in a collision between asteroids 170 and 60 kilometers in diameter, 40-kilometer-diameter Baptistina being the largest survivor.

    By assuming how reflective Baptistina family members are, the SwRI group could estimate the size of each asteroid from the amount of visible light they reflected. Their sizes, in turn, determined how quickly sunlight could ease debris away from the collision. As each fragment absorbs solar energy, it radiates the heat away to give an ever-so-gentle rocketing effect. That nudging could have driven fragments toward a known orbital spot from which Jupiter’s gravity could fling them toward Earth. Judging by how far from the collision Baptistina family members have gotten, the group estimated that the collision occurred about 160 million years ago, early enough for the solar-driven rocketing to drive a 5- or 10-kilometer fragment to the jumping-off point to Earth by 65 million years ago.

    But now team members on the Wide-Field Infrared Survey Explorer (WISE) mission dispute this line of evidence in a paper just out in The Astrophysical Journal. Joseph Masiero of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, and colleagues report that WISE has returned estimates of the size of 100,000 asteroids, the Baptistina family among them. These estimates are more accurate than those the SwRI group had because WISE detects infrared light, not the visible spectrum. The SwRI group had to assume a reflectivity, but the WISE infrared measurements yielded actual measurements of reflectivity that are four times larger than the SwRI group had assumed. That in turn gave smaller sizes, faster moving fragments, and therefore a younger collision time—about 80 million years ago—than the SwRI group had calculated.

    “This doesn’t give the remnants from the collision very much time to … get flung down to Earth 65 million years ago,” says Amy Mainzer, a co-author and the principal investigator of the asteroid phase of WISE at JPL. So instead of the Baptistina collision being ultimately responsible, another, as-yet-undated collision may have been responsible. Or the dino killer was a random asteroid that happened to wander out of the asteroid belt then.

    Bottke doesn’t see a problem. Indeed, the WISE results “if anything … make our story stronger,” he writes in an e-mail. The SwRI group’s 2007 calculations show that “lots of things escape from the Baptistina family right away … decreasing the age of the Baptistina family is not a problem.”

    Before, the collision was so early that the dino killer would have had to have been among the sparse debris that reached Earth long after the collision, Bottke says; with a more recent collision, far more Baptistina fragments would have been raining toward Earth 65 million years ago. Bottke’s argument “provides a good counterpoint to the conclusions reached by the WISE team,” writes dynamicist Derek Richardson of the University of Maryland, College Park. Now perhaps the prosecution and the defense can work on a settlement.

    Shoemaker Impact Structure, Western Australia

    Shoemaker Impact Structure, Western Australia : Image of the Day.

    Shoemaker Impact Structure, Western Australia

    acquired July 5, 2011 download large image (529 KB, JPEG)

    The Shoemaker (formerly Teague) Impact Structure—located in Western Australia in a drainage basin south of the Waldburg Range—presents an other-worldly appearance in this astronaut photograph. The Shoemaker impact site is approximately 30 kilometers (19 miles) in diameter and clearly defined by concentric ring structures formed in sedimentary rocks (brown to dark brown, image center). The rocks were deformed by the impact event approximately 1.63 billion years ago (as reported by the Earth Impact Database). Other age-dating analyses of granitic rocks at the core of the structure call this age into question (Pirajno et al. 2003).

    Several saline and ephemeral lakes—Nabberu, Teague, Shoemaker, and numerous smaller ponds—occupy the land surface between the ring structures. Differences in color result from both water depth and from suspended sediments, with some bright salt crusts visible around the edges of smaller ponds (image center). A Landsat 7 view of the Shoemaker structure illustrates the extent of these ephemeral lakes, or playas, in the region.

    The Teague Impact Structure was renamed Shoemaker in honor of Dr. Eugene M. Shoemaker (1928-1997), a pioneer in impact crater studies and planetary geology, as well as the founder of the Astrogeology Branch of the U.S. Geological Survey.

    1. Reference

    2. Pirajno F., Hawke, P., Glikson, A.Y., Haines, P.W., and Uysal, T. (2003). Shoemaker impact structure, Western Australia. Australian Journal of Earth Sciences, 50:775-796.

    Astronaut photograph ISS028-E-14782 was acquired on July 6, 2011, with a Nikon D2Xs digital camera using a 200 mm lens, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 28 crew. The image has been cropped and enhanced to improve contrast. Lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by William L. Stefanov, Jacobs/ESCG at NASA-JSC.

    Instrument: 
    ISS – Digital Camera

    Will Apophis Hit Earth in 2036?

    Will Apophis Hit Earth in 2036? | Asteroid & Space Rock Collisions | Space.com.

     

    2 Recent Asteroid Near Misses

    Earth’s Gravity Warped Asteroid’s Orbit | Asteroid 2011 CQ1, Tiny Asteroids & Space Rocks | NEOs, Near-Earth Objects | Space.com.

    This NASA graphic depicts the new flight path and trajectory of asteroid 2011 CQ1 after its Feb. 4, 2011 encounter with Earth. The tiny asteroid flew within 3,400 miles (5,471 kilometers) of Earth – a new record.
    This NASA graphic depicts the new flight path and trajectory of asteroid 2011 CQ1 after its Feb. 4, 2011 encounter with Earth. The tiny asteroid flew within 3,400 miles (5,471 kilometers) of Earth – a new record.
    CREDIT: NASA/JPL

    A tiny asteroid that zipped by Earth this month made the closest-ever approach to our planet without hitting it, an encounter that changed its place in our solar system forever, NASA scientists say.

    The asteroid, called 2011 CQ1, came within 3,400 miles (5,471 kilometers) of Earth on Feb. 4. Astronomers with NASA’s Near-Earth Object office now say the flyby set a record for a space rock.

    “This object, only about 1 meter in diameter, is the closest non-impacting object in our asteroid catalog to date,” wrote astronomers Don Yeomans and Paul Chodas in a post-flyby analysis. Both scientists work in the NEO office, at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

     

    Asteroid 2011 CQ1 was discovered only 14 hours before its close approach, which occurred over the mid-Pacific Ocean, but it never posed a threat to the planet because of its small size: 4 feet (1.3 meters) wide. Had it entered Earth’s atmosphere, it would have broken apart before reaching the ground, NASA scientists said.

    Record-setting asteroid encounter

    The asteroid’s flyby of Earth has changed its orbit, according to Yeomans and Chodas.

    Before its Earth encounter, asteroid 2011 CQ1 was one of the solar system’s so-called Apollo-class asteroids, whose orbits around the sun are mostly outside the orbit of Earth. [5 Reasons to Care About Asteroids]

    But during the Feb. 4 flyby, Earth’s gravitational pull warped the flight path of 2011 CQ1. Now the asteroid will spend “almost all of its time inside the Earth’s orbit” in what scientists call an Aten-class orbit, explained Yeomans and Chodas.

    The Earth’s gravity pulled asteroid 2011 CQ1 about 60 degrees off its original flight path, they added.

    February’s asteroid flybys

    Asteroid 2011 CQ1 was the first of two asteroids to zip past Earth within a span of six days. Another space rock – the car-size asteroid 2011 CA7 – came within 64,300 miles (103,480 km) of Earth when it passed by on Feb. 9.

    Astronomer Richard A. Kowalski of the Catalina Sky Survey discovered asteroid 2011 CQ1 just before its flyby, and scientists at Remanzacco Observatory in Italy snapped a photo of the object ahead of the close pass.

    NASA and other scientists monitor the skies for asteroids or comets with orbits that cross that of the Earth in order to track near-Earth objects that could pose an impact threat to our planet. Tiny asteroids like 2011 CQ1 are difficult to spot but pose no threat to Earth.

    “There is likely to be nearly a billion objects of this size and larger in near-Earth space, and one would expect one to strike Earth’s atmosphere every few weeks on average,” Yeomans and Chodas wrote. “Upon striking the atmosphere, small objects of this size create visually impressive fireball events but only rarely do even a few small fragments reach the ground.”