Asteroids | Universe Today

What would happen if we spot a Near-Earth Asteroid (NEO) heading straight for us? Assuming we had enough time, we might be able to pull together a group of brave astronauts (or oil drillers) and send them to the asteroid just in the nick of time to destroy it… oh hold on, that sounds like the storyline for a Hollywood blockbuster. Actually, NASA is planning a mission to an NEO, but not because it's aimed at us. An asteroid named 2000SG344 (which threatened the Earth in the year 2000) is being considered as the destination for the first manned asteroid mission. The asteroid astronauts will travel there, chasing the 28,000 mi/hr (45,000 km/hr) speeding body and then carry out experiments, living on it for up to two weeks. Why? To briefly establish a manned outpost, advancing science and technology toward the ultimate goal: Mars.
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There are just so many ways the Universe is out to get us. Astronomers have already considered the threat from our Sun's orbit around the center of the Milky Way. When our Sun rises up out of flat plane of the Milky Way, it appears we might be less protected from intergalactic radiation and cosmic rays. Well, it looks like passing through the middle of the galactic plane might have its own share of risks: an increased number of comets might be hurled towards the Earth because of gravitational interaction with the densest parts of our galaxy.
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When a large enough asteroid strikes the Earth, the devastation effects the entire globe. And the dinosaur-killing asteroid that smashed into the Yucatan peninsula 65 million years ago was no exception. According to researchers, just one outcome from the strike: carbon in the Earth's crust was liquified and formed tiny beads that rained back down across the entire planet.
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Question: How Big is Apophis?

Answer: In case you haven't heard, Asteroid 99942 Apophis is a near Earth asteroid that astronomers think will make a close flyby to the Earth in 2029. When its trajectory was first calculated back in 2004, it had one of the closest visits to Earth astronomers had seen, and had a 2.7% chance of hitting the Earth.

But follow-up observations brought that risk down to 1 in 45,000. Right now, astronomers think that Apophis is essentially no risk to the Earth. In April, 2008 media reported that a 13-year old German student had caught a math mistake made by NASA, and the risk of an Earth strike was actually 1-45. This later turned out to be a hoax.

Because of its close approach to Earth, space advocacy societies, including the Planetary Society think that Apophis would make an ideal target for a human mission, and allow engineers to test out strategies for moving asteroids away from dangerous Earth-crossing orbits.

So back to the original question, how big is Apophis? The best estimate puts it at 270 meters (885 feet across), and it has a mass of 2.1 x 10¹⁰ kg. To give you a sense of scale, the Eiffel Tower in Paris is 324 meters tall.

But now you know its mass and size, you're probably wondering: what would happen to the Earth if it struck? NASA estimated that a strike by Apophis would release the equivalent of 880 megatons of energy. Just as a comparison, the object that carved out Meteor Crater in Arizona probably released 3-10 megatons of energy.

If Apophis struck land, it would flatten thousands of square km of land, killing millions of people if it hit a densely populated area. But it wouldn't cause the kinds of long term climate destruction that 1 km and larger asteroids can do. If it hit an ocean, it would create devastating tsunamis in all directions.

Here's an article explaining techniques that might be used to move an asteroid. And here's NASA's official page on Apophis.

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Update: It turns out this story is a fabrication and AFP didn't check the facts with NASA as I suspected. According to the blog Cosmos4u, they talked with Don Yeomans at NASA's NEO office and this is what Yeoman's said about the news story of a 13-year old boy correcting NASA's estimates of Apohpis impacting earth: "We have not corresponded with this young man and this story is absurd, a hoax or both. During its 2029 Earth close approach, Apophis will approach the Earth to about 38,900 km, well inside the geosynchronous distance at 42,240 km. However, the asteroid will cross the equatorial belt at a distance of 51,000 km - well outside the geosynchronous distance. Since the uncertainty on Apophis' position during the Earth close approach is about 1500 km, Apophis cannot approach an Earth satellite. Apophis will not cross the moon's orbital plane at the Moon's orbital distance so it cannot approach the moon either."

Also, the scientist mentioned in AFP's story said he wasn't conferred with either by the news agency. So don't give any heed to this story that has been running amok around the internet.

But here's our story on this as it originally ran: Here’s a story that supports the value of science fairs. And it also makes one wonder where else NASA’s decimal points might be off by a couple of places. One caveat on this news piece, however: as far as I know there hasn’t been an official NASA press release on this.

Reportedly, a 13-year-old German schoolboy doing research for a science competition found errors in NASA's estimates on the chances of the asteroid Apophis colliding with Earth. The boy, Nico Marquardt used data from the Institute of Astrophysics in Potsdam to calculate that there was a 1 in 450 chance that the Apophis asteroid will collide with Earth. NASA had previously estimated the chances at only 1 in 45,000, but according to an AFP news release, NASA now acknowledges the kid is right. (Actually, no they don't.)
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Way back in the beginning of the solar system, about 4.5 billion years ago, the first materials began to condense from gasses into solid particles. These materials were rich in calcium and aluminum. Astronomers have thought that at least some of the solar system’s oldest asteroids should have plenty of these two elements, but no asteroids had ever been found that were particularly rich in them. Until now. A team of scientists recently identified three previously unknown asteroids that appear to be among the oldest objects in our solar system.
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Yesterday we talked about the discovery of amino acids in meteorites. And then today comes news that there was an explosion of life (pardon the pun) after meteorites rained down more than 400 million years ago. Even though the Earth was struck by more than 100 1-km meteorites in a short period of time, life not only survived, it thrived.
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Does this mean that, perhaps, we can go home again? If an asteroid or comet impacted Earth, the resulting ejection of materials could contain life forms. According to a study published in the journal Astrobiology, these life forms could survive and then seed another planet or moon with life. Additionally, Earth could also be re-seeded with life by those same life forms. Ah, there’s no place like home.
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The Near Earth Asteroid (NEO) Apophis is expected to flyby the Earth in 2029. However, this flyby will be more of a "fly-very-close" as the lump of rock will miss the Earth by only a few thousand kilometers. This near-miss isn't worrying scientists too much, but should the asteroid tumble through a 400 meter gravitational "keyhole", there is concern that the asteroid could swing by and risk another collision in 2036. Although the odds are fairly slim, astronomers need better precision in calculating Apopis's orbital trajectory.

How can this be done? Why not send a spaceship to shadow the asteroid on its journey? The Planetary Society has announced just that. The winning design of the Apophis Mission Design Competition will send a probe and tag Apophis to gain more details about this interplanetary vagabond, and has been awarded a healthy $25,000 to help the development of the US "Foresight" mission…
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Primordial black holes (PBHs) are getting mischievous again. These artefacts from the Big Bang could be responsible for hiding inside planets or stars, they may even punch a neat, radioactive hole through the Earth. Now, they might start playing interplanetary billiards with asteroids in our solar system.

Knocking around lumps of rock may not sound very threatening when compared with the small black holes' other accolades, but what if a large asteroid was knocked off course and sent in our direction? This could be one of the most catastrophic events yet to come from a PBH passing through our cosmic neighborhood…
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Although the chances of an asteroid hitting Earth appear to be small for any given year, the consequences of such an event would be monumental. The science community has come up with some ideas and proposals for ways to mitigate the threat of an incoming asteroid hitting the Earth. Some proposals suggest almost Hollywood type theatrics of launching nuclear weapons to destroy the asteroid, or slamming a spacecraft into a Near Earth Object to blow it apart. But other ideas employ more simple and elegant propositions to merely alter the trajectory of the space rock. One such plan uses a two-piece solar sail called a solar photon thruster that draws on solar energy and resources from the asteroid itself.
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Since asteroids have mass, they have gravity. And if you've got gravity, you can have moons. Several asteroids have been discovered in the outer Solar System with smaller asteroidlets circling them. But now the Arecibo radio telescope in Puerto Rico has turned up the closest example - a triple system just a mere 11 million km (7 million miles) from Earth.
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On Tuesday, February 5, 2008 an SUV sized asteroid passed between the Earth and the moon. Asteroid 2008 CT1 came within135,000 kilometers ( 84,000 miles) of Earth, only a third of the distance to the moon. The asteroid was discovered only two days before its close approach to Earth, spotted by the Lincoln Near Earth Asteroid Research (LINEAR) project, using robotic telescopes located at New Mexico’s White Sands Missile Range. The asteroid’s size is estimated between 8 - 15 meters.
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At the time I'm writing this, asteroid 2007 TU24 has nearly passed the Earth. As we've been hammering on here on Universe Today, the Earth is completely safe. Only if you have a telescope and know exactly where to look, will you stand a chance of spotting the flyby.

Even though he posted a video last week, debunking the collision claims, Bad Astronomer and (former) friend Phil Plait seems to have recanted.

Lowest form of life? Ouch.

Thanks to IronmanAustralia for the laugh. I'm still wiping the tears out of my eyes.

On another note, this is the first time I've tried embedding a YouTube video in Universe Today. I'm sure I've messed it up somehow. Let me know if you like this, and want more.

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In case you had any doubts, it’s now official: Asteroid 2007 TU 24 will not impact or have any affect on Earth. Astronomers have obtained the first images of the near earth asteroid using high-resolution radar data. "With these first radar observations finished, we can guarantee that next week's 1.4-lunar-distance approach is the closest until at least the end of the next century," said Steve Ostro, Jet Propulsion Laboratoy astronomer and principal investigator for the project. "It is also the asteroid's closest Earth approach for more than 2,000 years."
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Just so it's clear in your mind: comets are dirty snowballs, asteroids are rocks. Got the difference? Wait… not so fast. Scientists studying the cometary dust picked up by NASA's Stardust spacecraft, and they're finding it's surprisingly asteroid like.
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An asteroid between 150-160 meters in diameter will pass within 540,000 kilometers (334,000 miles) of Earth on January 29 at 08:33 UT (3:33 EST). Hopefully this news won’t cause any alarmist cries of doom, as the asteroid has no chance of hitting Earth (yeah, right, the alarmists are already out in full force). But there is one reason to get excited about this close approach by an asteroid: it will be close enough to likely be visible to amateur astronomers.
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One of the most spectacular sights in the night sky is a fireball; a rock from space impacts the atmosphere and blazes a trail that can last seconds or even minutes. These burn up harmlessly, but when do they turn dangerous? When do asteroids get large enough that they can actually get through the atmosphere and cause some destruction here on the ground?
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Sorry to disappoint those of you hoping for some Martian fireworks the end of this month. NASA’s Near Earth Object (NEO) Program office has effectively ruled out the possibility of Asteroid 2007 WD5 impacting Mars. The probability of such an event has dropped dramatically, to approximately 0.01% or 1 in 10,000 odds of an impact. Observers also say the asteroid has no possibility of impact with either Mars or Earth anytime in the next century.
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A 164-foot (50 meter) wide asteroid will be crossing the orbit of Mars at the end of January 2008. Currently, there is a 1-in-75 chance of the "Mars Crosser" hitting the Red Planet, and if it does, the 30,000 mile per hour speeding mass would generate a three megaton explosion (approximately the size of the terrestrial Tunguska impact over Siberia in 1908) and create a crater half-a-mile wide somewhere north of Meridiani Planum. So, the Mars Rover Opportunity will get a ringside seat should this once-in-a-thousand-year event occur…
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When astronomers first made the connection between asteroid impacts and extinction events on Earth, it was kind of frightening. There are hundreds of thousands of those things out there zipping around! But dedicated asteroid hunters have located many of the largest planet smashers, and new programs are in the works to find the rest. But now it seems that even the smaller asteroids could be more destructive than previously believed.
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Remember when I mentioned that ESA's Rosetta was inbound to make a flyby of the Earth on November 13th? Well, another group of astronomers were watching this "unknown" object, and thought that it was actually an asteroid that was going to be making a close flyby of our planet. The astronomers realized their mistake, but not after an alert was sent out to the astronomical community. Oops.
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It's a cosmic whodunit: a meteorite exploded in the air near a remote part of Russia called Tunguska in 1908, and the meteorite that caused the event all but disappeared. Where did it come from? Was it an asteroid or part of a comet? Astronomers have taken up the case, using mathematical simulations to track down the perpetrator. They even think they might even know a few of its siblings.
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A team of undergrad astronomers at the University of Washington figured out how to turn an annoyance into a major discovery, uncovering 1,300 new asteroids; nearly 1 out of every 250 known objects in the Solar System. How did they pull of this feat? It was actually a side project to their actual research: searching for supernovae. The asteroids were getting in the way.
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The big day arrived, and nothing could keep that spacecraft on the ground. At 7:34 am EDT NASA's Dawn spacecraft was lofted into space atop a Boeing Delta 2 rocket, beginning a 3 billion km (1.7 billion mile) journey to meet with two different large asteroids. If all goes well, the spacecraft will make its first encounter with Vesta in October, 2011, and then Ceres in February, 2015.
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