Tag Archives: space collision

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.

‘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.



    Space Junk Collision Could Set Off Catastrophic Chain Reaction, Disable Earth Communications

    Pentagon: A Space Junk Collision Could Set Off Catastrophic Chain Reaction, Disable Earth Communications | Popular Science.


    Orbital Debris The dots on this NASA-generated chart represent known pieces of large orbital debris. NASA

    Every now and again someone raises a stern warning about the amount of space junk orbiting Earth. Those warnings are usually met with general indifference, as very few of us own satellites or travel regularly to low Earth orbit. But the DoD’s assessment of the space junk problem finds that perhaps we should be paying attention: space junk has reached a critical tipping point that could result in a cataclysmic chain reaction that brings everyday life on Earth to a grinding halt.

    Our reliance on satellites goes beyond the obvious. We depend on them for television signals, the evening weather report, and to find our houses on Google Earth when we’re bored at work. But behind the scenes, they also inform our warfighting capabilities, keep track of the global shipping networks that keep our economies humming, and help us get to the places we need to get to via GPS.

    According to the DoD’s interim Space Posture Review, that could all come crashing down. Literally. Our satellites are sorely outnumbered by space debris, to the tune of 370,000 pieces of junk up there versus 1,100 satellites. That junk ranges from nuts and bolts lost during spacewalks to pieces of older satellites to whole satellites that no longer function, and it’s all whipping around the Earth at a rate of about 4.8 miles per second.

    The fear is that with so much junk already up there, a collision is numerically probable at some point. Two large pieces of junk colliding could theoretically send thousands more potential satellite killers into orbit, and those could in turn collide with other pieces of junk or with satellites, unleashing another swarm of debris. You get the idea.

    To give an idea of how quickly a chain reaction could get out hand consider this: in February of last year a defunct Russian satellite collided with a communications satellite, turning 2 orbiting craft into 1,500 pieces of junk. The Chinese missile test that obliterated a satellite in 2007 spawned 100 times more than that, scattering 150,000 pieces of debris.

    If a chain reaction got out of control up there, it could very quickly sever our communications, our GPS system (upon which the U.S. military heavily relies), and cripple the global economy (not to mention destroy the $250 billion space services industry), and whole orbits could be rendered unusable, potentially making some places on Earth technological dead zones.

    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.


    (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.

    Space Junk Problem Is Waxing Threat

    Space Junk Problem Is More Threatening Than Ever, Report Warns | NASA’s Micrometeoroid and Orbital Debris Programs | National Research Council Report | Space.com.

    An artist's illustration of a satellite collision that destroys a spacecraft in orbit.
    An artist’s illustration of a satellite collision from space debris in orbit. Space traffic accidents only beget more such accidents.
    CREDIT: European Space Agency

    There is so much junk in space that collisions could start to increase exponentially, leading to a continuously growing pile of rubble in orbit, a new report warns.

    The independent report, released today (Sept. 1), surveyed NASA’s work to meet the threat of space debris. It was sponsored by NASA, and conducted by the National Research Council, a nonprofit science policy organization.

    Space debris — an accumulation of broken satellites, spent rocket stages and other junk in orbit — is dangerous because it could hit and damage working satellites, as well as spacecraft like the International Space Station. [Worst Space Debris Events of All Time]


    Furthermore, when two pieces of junk collide, they can break apart into many smaller pieces, significantly increasing the amount of debris in space. This happened, for example, in the 2009 crash of a U.S. Iridium communications satellite and a broken Russian spacecraft.

    It’s a problem that will likely become more visible, and urgent, over time.


    Kessler Syndrome

    “Space is becoming essential to our current civilization,” Donald Kessler, chairman of the report committee and retired head of NASA’s Orbital Debris Program Office, told SPACE.com. “If for any reason we weren’t able to use satellites as easily as we do today, there would be a reduction in the standard of living.”

    The situation we’re in now is called the Kessler Syndrome, a term named after Kessler, in which the amount of debris has reached a critical threshold. There is now enough orbital debris that collisions will cause a continual cascade, with each adding to the total amount of debris and increasing the chances of further collisions, according to several studies, Kessler said.

    “Even if we add nothing else to orbit, the amount of debris could continue to increase as a result of random collisions between fairly large objects,” Kessler said. “You’d generate debris faster than the natural decay process could return it.”

    Budget woes

    But while the dangers posed by growing orbital detritus are increasing, NASA’s budget and management structure has not kept pace, the new report found.

    “The program really started from the ground up and has expanded over the last 35 years considerably, and has a lot more facets to it,” Kessler said. “Its responsibility keeps increasing, but the management and funding just has not kept up with the program.”

    Another complication is the fact that most of NASA’s space debris programs consist of a single staff member.

    “If anyone retires or moves you have a pretty large gap,” Kessler said. “There’s usually just one civil servant that’s been charged with a whole bunch of things.”

    Primary among the report’s recommendations is for NASA to come up with a strategic plan to prioritize the areas within its micrometeoroid and orbital debris program that deserve the most funding and attention.

    This computer illustration depicts the density of space junk around Earth in low-Earth orbit.
    This computer illustration depicts the density of space junk around Earth in low-Earth orbit.

    Crunching the numbers

    The report also highlighted the need for NASA to spearhead the gathering of urgently needed data in several areas to improve scientific models and predictions of the effect of debris collisions. For example, the committee recommended that NASA study the differences in how various types of spacecraft behave and break up during a collision.

    The report also recommends that NASA help establish a better database of information about spacecraft anomalies. Too often companies don’t share details about problems that occur on their satellites, often for proprietary reasons. But this information is important for calculations about how spacecraft fail and become uncontrollable.

    Kessler suggested that an anonymous registry would allow companies to share information without attaching their names to the data.

    Currently, NASA’s programs focus on studying and tracking orbital debris. At some point, however, it will likely become necessary to somehow remove especially risky pieces of junk from orbit. That will require technology that doesn’t exist yet.

    “The program has been very good at identifying the need to clean space, but in terms of the how-you-do-it part, the technology required is going to require quite a lot of work,” Kessler said.

    You can follow SPACE.com senior writer Clara Moskowitz on Twitter @ClaraMoskowitz. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

    NASA Tracking Potentially Dangerous Space Junk Near Shuttle & ISS

    NASA Tracking Potentially Dangerous Space Junk Near Shuttle, Space Station | Atlantis’ STS-135 Mission | International Space Station & Space Debris | Space.com.

    Again, a bit tardy in posting….

    HOUSTON – NASA is tracking a piece of space junk that could fly close to the International Space Station and the connected shuttle Atlantis, officials announced today (July 10).

    Mission managers were notified of the potentially threatening piece of space trash this morning, and are continuing to observe the object to determine whether they need to take any action to avoid a collision. [Video: Space Junk Threat Grows]


    “We will work through our normal procedures and processes for dealing with that,” LeRoy Cain, chair of Atlantis’ mission management team, said in a news briefing today. “What we were told today was very preliminary.”

    This potentially threatening piece of space junk is debris from a defunct Russian satellite that was launched in 1970, and is part of a known catalog of derelict objects in orbit. After further analysis, NASA will better understand the size and orbit of the debris, and whether or not it poses a threat to the shuttle and station.

    Based on initial assessments, the object is expected to make its closest approach at 12:59 p.m. EDT (1659 GMT) on Tuesday (July 12), during a scheduled spacewalk by station astronauts Ron Garan and Mike Fossum.

    If deemed necessary, mission managers will use small thrusters aboard Atlantis to maneuver the shuttle and station out of harm’s way, and allow both the shuttle and station crews to press ahead with their mission objectives.

    “In all likelihood, it would not interfere with what we’re doing on the spacewalk,” Cain said.

    Space junk, which consists mostly of spent rocket parts and pieces of broken satellites ranging in size, is an ongoing threat to spacecraft and satellites in orbit. Today, more than 22,000 pieces of space junk are constantly being tracked in Earth orbit.

    NASA and its space station partners have procedures in place to deal with potentially threatening pieces of orbital debris if they fly within a preset safety perimeter around the station and any attached spacecraft. With advance notice, thrusters on the space station itself, or any attached vehicles such as the shuttle or Russian Soyuz spacecraft, can be used to move the complex to a higher orbit to get out of the way, for example.

    NASA maintains a pizza box-shaped safety zone that measures just over 15 miles (25 kilometers) around the space station and about a half-mile (0.75 km) above and below the outpost.

    “It’s not uncommon,” Cain explained. “There’s a lot of junk in orbit. We have a very good process for knowing where they are and how to avoid them in cases where we need to avoid them. It’s not unusual to have to deal with it.”

    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.

    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.”


    Space Station's Brush with Space Junk Highlights Growing Threat | Space Debris Threat & Orbital Debris Problem

    Space Station’s Brush with Space Junk Highlights Growing Threat | Space Debris Threat & Orbital Debris Problem | International Space Station & Astronaut Risk | Space.com.

    Sunlight glints off the International Space Station.
    Sunlight glints off the International Space Station with the blue limb of Earth providing a dramatic backdrop in this photo taken by an astronaut on the shuttle Endeavour just before it docked after midnight on Feb. 10, 2010 during the STS-130 mission.

    The near-miss yesterday (June 28) between the International Space Station and a piece of space junk highlights the growing threat posed by the huge cloud of debris whizzing around Earth.

    The piece of space debris zipped uncomfortably close to the orbiting lab Tuesday at 8:08 a.m. EDT (1208 GMT), forcing the outpost’s six astronauts to take shelter in two docked Russian Soyuz lifeboats for only the second time ever. The spaceflyers would have attempted a speedy escape in the craft had a collision occurred and severely damaged the space station.

    The station’s shielding protects it from a near-constant pelting by tiny motes of fast-moving debris. But those defenses would likely have been breached had the object slammed into the orbiting lab yesterday. The piece was large enough to be tracked, meaning it was at least 4 inches (10 centimeters) in diameter, NASA officials said.


    It was a close call, and was the closest a dangerous piece of debris has ever come to hitting the station, NASA officials said. [Worst Space Debris Events of All Time]

    “We tracked the object after it came past station,” Bill Gerstenmaier, NASA’s space operations chief, said in a news briefing on Tuesday. It “came within 335 meters of space station on best estimate.”

    Massive cloud of debris

    Pieces of space trash — which may be defunct spacecraft, abandoned launch vehicles or fragments from satellite collisions — zip around Earth at speeds up to 17,500 mph (28,163 kph).

    This computer illustration depicts the density of space junk around Earth in low-Earth orbit.
    This computer illustration depicts the density of space junk around Earth in low-Earth orbit.

    That’s so fast that even orbiting paint flecks can damage a spacecraft. And there’s a lot of this stuff, much of it larger and far more dangerous than paint flecks. For example, NASA estimates that there are at least 20,000 pieces at least 4 inches wide — as big as a softball — and more than 500,000 bigger than a marble.

    NASA and the Space Surveillance Network operated by the Department of Defense track the debris, but the huge numbers make this a daunting challenge. And the numbers just keep growing, as more material is launched and more orbiting objects crash into each other.

    Sometimes this happens by accident, as was the case of a 2009 collision between a defunct Russian satellite and a U.S. Iridium communications satellite. This smash-up added at least 2,000 pieces of space junk to the total, NASA officials said.

    But sometimes collisions occur by design. A 2007 Chinese anti-satellite test, for example, added about 3,000 pieces of space junk to the orbiting population.

    NASA, DARPA and other researchers have been studying potential ways to clean up space debris , including looking at ways to reduce the amount of junk created during new rocket launches.

    Danger to spacecraft and astronauts

    The space station’s armor can generally withstand impacts by debris up to 0.8 inches (2 cm) in diameter, NASA researchers have said. But the huge numbers of large objects mean that a collision with a dangerous piece of space junk is a real possibility.

    In fact, the chances of having to evacuate some of the space station’s crew and send them home to Earth due to orbital debris is about 1-in-100 during every six-month period, NASA spokesman Kelly Humphries told SPACE.com. The average length of a station crew’s mission is about six months.

    NASA does what it can to minimize those risks. If it detects a dangerous piece of space debris soon enough, the station can be directed to make evasive maneuvers. That didn’t happen in yesterday’s near-miss, which came with just 14 hours of notice instead of the necessary three days or so.

    The orbiting lab has made a dozen such maneuvers since 1999, including one this past April when space trash spawned by the 2009 satellite collision posed a threat.

    But spacecraft aren’t the only objects potentially in the line of fire. Even pieces just a few millimeters wide could be deadly to astronauts out on spacewalks (also known as extravehicular activity, or EVAs).

    That’s a cause for real concern, and a driving force in the effort to better track space junk and micrometeoroids — tiny chunks of rock that whiz through space.

    “In the lifetime of the International Space Station, up to 2020, there’s a 1-in-12 chance we will lose an astronaut on an EVA” because of micrometeoroids or space junk, Bill Cooke, chief of the Meteoroid Environment Office at NASA’s Marshall Space Flight Center, said last month at the 2011 International Space Development Conference in Huntsville, Ala.

    Countries 'most at risk' from an asteroid strikes

    Britain ‘most at risk’ from an asteroid strikes, days after UFO’s seen over BBC London office – International Business Times.

    Experts at Southampton University have drawn up a league table of countries most likely to suffer severe loss of life or catastrophic damage should a large asteroid hit Earth. The news comes days after UFOs were apparently spotted flying over the BBC building in London. (EDITOR’S NOTE: this has been proven a hoax)

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    The countries most at risk from an asteroid strike are Brazil, Britain, China, India, Indonesia, Italy, Japan, Nigeria, The Philippines and The U.S.

    Coincidently, most of the list is made up of developed nations including China, Japan, the United States and Italy, on the basis that the size of their populations would mean millions of deaths.

    The US, China, Indonesia, India and Japan are most in danger on this basis. Canada, the US, China, Japan and Sweden are rated most at risk in terms of potential damage to their infrastructure.

    The report comes after a rock the size of a house came within 7,500 miles of Earth earlier this week.

    The list has been compiled using software called NEOimpactor, using data from NASA’s Near Earth Object programme.

    “The threat of Earth being hit by an asteroid is increasingly being accepted as the single greatest natural disaster hazard faced by humanity,” said Nick Bailey, of the University of Southampton, who developed the NEOimpactor software.

    “The consequences for human populations and infrastructure as a result of an impact are enormous.”

    Mr Bailey also pointed out that an asteroid which landed in a remote spot near the Tunguska River in Russia in 1908 devastated very large perimeter and the impacts would have been catastrophic if the place had been populated.  “While it only flattened unpopulated forest, had it exploded over London it could have devastated everything within the M25,” he said.

    “Our results highlight those countries that face the greatest risk from this most global of natural hazards and thus indicate which nations need to be involved in mitigating the threat.”

    Scientists think that, 65 million years ago, an asteroid was responsible for the extinction of the dinosaurs as a rock up to 10 miles in diameter hit Earth at 25,000 an hour with a force of 100 megatons, the equivalent of one Hiroshima bomb for everyone on the planet.

    Many also insist that if Earth has until now managed to avoid being hit by such a large asteroid, it is partly due to Jupiter’s gravitational field which limits our exposure to space rocks and thus protect us unintentionally.