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Earth in near miss asteroid encounter
« on: 2009-03-03 15:15:52 » |
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His aim is getting better !
Cheers
Fritz
Source: The Tech Herald
Author: Stevie Smith
Date: Mar 2 2009, 18:08
Note: This is not DD45 2009. It's a comet from 2007. Image: wonderferret/Flickr.
While most of the world nonchalantly went about its business on Monday, March 02, a few twitchy stargazers were intently following the path of a near-Earth asteroid carrying the potential to create significant damage to the planet’s surface.
Although the snappily named DD45 2009 narrowly avoided a collision with Earth, passing by harmlessly at a distance of around 40,000 miles, space rock experts believe the 200ft asteroid was a significant event and something of a fanfare-free near miss.
Speaking with Canadian publication the Ontario Citizen, astronomer Peter Brown of the University of Western Ontario said DD45 2009 was equivalent in size to the Tunguska asteroid that exploded above Siberia in 1908 and obliterated thousands of square miles of remote forestry.
According to Brown, “the last rock as large or larger than this to come this close was in 1973 and the next time will be in 2029 when Apophis makes its close approach.”
The Apophis asteroid initially caused some consternation with scientists when its plotted course revealed it to be on a collision trajectory with Earth. However, further investigation has since shown it will pass harmlessly by.
That being said, there are only a select amount of experts with their eyes trained to the heavens and many other potentially dangerous space objects could yet take the planet by surprise. Case in point, DD45 2009 was only discovered and tracked on February 27.
In order to provide increased coverage when searching
space for asteroids and comets in the future, Canada is planning to launch its NEOSSat satellite (Near Earth Object Surveillance Satellite) into orbit in 2010.
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Re:Earth in near miss asteroid encounter
« Reply #1 on: 2009-03-25 21:23:09 » |
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First-Ever Asteroid Tracked From Space to Earth
Source: Wired
Author: Betsy Mason
Date: March 25, 2009
For the first time, scientists were able to track an asteroid from space to the ground and recover pieces of it. The bits are unlike anything ever found on Earth.
The asteroid was spotted entering Earth's atmosphere over Sudan in October and was believed to have fully disintegrated, but an international team found almost 280 pieces of meteorite in a 11-square-mile section of Sudan's Nubian Desert. The largest was the size of an egg. Lab analysis showed that the rocks belong to a rare class of asteroid that has never been sampled in such a pristine state, so it could fill some gaps in our understanding of the solar system's early history.
"It's the first time we've been able to track something through the air and watch it fly apart and then find pieces of it," microbial ecologist Rocco Mancinelli of SETI, a co-author of a study on the meteorite pieces Wednesday in Nature, told Wired.com.
Finding the meteorites was a long shot, but because the rocks would be so important, meteor astronomer Peter Jenniskens of SETI, lead author of the study, took a bus loaded with 45 students and staff from the University of Khartoum deep into the desert to hunt for them. A 10-hour bus ride and an 18-mile trek through the sand took them to the remote area where scientists thought the rocks, if they existed, would be. The group began sweeping the desert in a line and two hours later the first meteorite was found by a student.
"It was very, very exciting. Everybody was celebrating," Jenniskens said. "You have to remember how important it is to find a piece linked to an asteroid we have seen in space."
Scientists use asteroids to learn about the early solar system because they are among the oldest objects in the universe and can remained relatively unchanged from when they formed, providing a historical snapshot. It is estimated that hundreds of meteorites fall to Earth each year, but only a few end up in the hands of scientists.
 Because asteroids are typically surrounded by a shroud of dust as they travel through space, they reflect light differently in flight than they do in the lab, making it difficult to connect meteorites found on Earth with particular types of asteroids. But because the car-sized Sudan asteroid was spotted 20 hours before it hit Earth's atmosphere, scientists were able to determine that it was an unusual type of asteroid that falls between the two most common types.
For the first time, scientists can begin to connect the light signatures of asteroids in space to signatures of meteorites in the lab.
"This is like the first step toward a Rosetta Stone for classifying asteroids," said study co-author, cosmic mineralogist Michael Zolensky, at a press conference at NASA's Johnson Space Center Wednesday.
The team, led by Jenniskens, hopes the intermediate meteorites will reveal details about how planets formed in the early solar system.
"It gives a window on the past," Jenniskens told Wired.com. "You see a little piece of early history coming into focus."
The Sudan meteorites are from a rare class of asteroids known as ureilites, which contain a lot of carbon, much of it in the form of graphite, as well as diamonds produced by shock. The Sudan specimens show evidence of volcanic activity, which means they came from a parent body that was almost big enough to call a planet.
"It's showing us that this asteroid had planet-like activity on it," said astronomer Lucy McFadden of the University of Maryland, who was not involved in the study. "We're lucky that the Earth was in the right place and placed itself in front of this new meteorite."
But that planet shut down, lost its heat source and quit growing, Zolensky said. This gives scientists a glimpse of a specific stage in the evolution of planets.
"What this does is give us first-hand knowledge of what happens when planetesimals form from one that fell apart and failed to become a planet," Mancinelli said. "It really tells you what happens when these rocks bang into each other and some actually stick to each other and form a planetesimal."
There's nowhere else to find this sort of information, he said, because you need the planet forming process to stop before it becomes a full-fledged planet.
"This is highly unusual," Mancinelli said. "It is key to understanding the early solar system."
Space scientist Ted Bunch at Northern Arizona University studies these rare meteorites. "Of the tens of thousands of meteorites that have been found, there's probably only 100 that are ureilites," he said.
Ureilites are interesting in that they have a very primitive composition, Bunch said. And the Sudan ureilite pieces are even more rare because they were picked up so soon after they fell. Meteorites that have been lying around on Earth for a long time can become contaminated.
"To see something which is pristine, the chance of contamination is pretty low," Bunch said. "Whatever you see in the stone is what came from outer space, with no contribution from Earth."
Image 1: The contrail left by the asteroid's passage through the atmosphere.Credit: Muawia Shaddad.
Image 2: Typical meteorite fragment. Credit: Muawia Shaddad.
Image 3: This space-based view of the Nubian Desert shows altitude in kilometers (in white circles) and meteor locations in red. Credit: NASA Ames/SETI/JPL.
Image 4: Students from the University of Khartoum line up to go meteorite hunting in the Nubian desert. Credit: Muawia Shaddad.
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Where there is the necessary technical skill to move mountains, there is no need for the faith that moves mountains -anon-
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MoEnzyme
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Re:Earth in near miss asteroid encounter
« Reply #2 on: 2009-03-26 10:06:18 » |
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Quote from: Fritz on 2009-03-03 15:15:52 His aim is getting better !
Cheers
Fritz |
"His aim" has always been stochastic. Its like the gambler at the slot machine who comes to believe it is "due" for a payout when in fact any pull of the handle is as likely as any other pull to payout. In any case it is at least as important to develop a deflection strategy for potential asteroid/comet impacts as it is to get the buildup of greenhouse gas under some control. In that respect it may help for motivational purposes to imagine "his aim getting better", because even though we are never "due" we can still be certain of the inevitability of future catastropic impacts. We know simply by looking at our planet's past that his aim has always been good enough - we just weren't around to appreciate it at the time. Thanks for the thread; it is certainly as important in the long run as "the flipping point".
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I will fight your gods for food,
Mo Enzyme
(consolidation of handles: Jake Sapiens; memelab; logicnazi; Loki; Every1Hz; and Shadow)
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Hermit
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Re:Earth in near miss asteroid encounter
« Reply #3 on: 2009-03-26 15:21:58 » |
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Bad news for the stochastically inclined. Slot machines are no longer driven by random numbers and have not been since the 1970s.
Modern one armed bandits are very competent money-extractors, far more competent than mere chance would suggest. Payouts are driven on a mathematical basis of predetermined amounts at predetermined intervals across a cluster of machines, carefully tuned to maximize income while ensuring that payouts are always happening within sight of the losers playing them as this encourages the idea that they will "win" if they ignore their losses and continue to feed the machines.
As for the rest, Mo is completely correct, but in my opinion, if we seek long-term relevance for ourselves or our ideas, I don't think he goes nearly far enough. We need to distribute off planet and out of the solar system, preferably out of the galaxy, but at least over 6000 light years, as soon as may be, because there is total certainty that life as we know it will become impossible at some time in the not too distant future.
How long we have is not known, but many theories suggest that we may be "overdue" for a serious die-off event. To learn more, http://en.wikipedia.org/wiki/Extinction_event might be a good place to begin.
Kindest Regards
Hermit&Co
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With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. - Steven Weinberg, 1999
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Fritz
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Re:Earth in near miss asteroid encounter
« Reply #4 on: 2009-03-26 19:49:34 » |
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Quote:[Mo]<snip>Its like the gambler at the slot machine who comes to believe it is "due" for a payout<snip>
[Hermit]Bad news for the stochastically inclined. Slot machines are no longer driven by random numbers and have not been since the 1970s.<snip> |
MoEnzyme some days I not sure what we are going to do with Hermit. He has shattered so many sacredly held self evident truths, that I fear with spring solstice coming he will tell us there is no Easter bunny and the joy of biting off the ears off of chocolate bunnies before the grand kids get to them will be compromised; and I may have to go back to sacrificing small barnyard animals. :-)
Cheers
Fritz
Flying Up to Meet Asteroids
Soource: POPSCI
Author:Rebecca Boyle
Date: 03.25.2009
A proposed NASA mission to intercept an ill-omened rock in the sky
Asteroid Ida and Its Moon, Dactyl: NASA
Partly to help explain solar eclipses, the ancient Egyptians had a story about the serpent god Apep, the Uncreator, who tried to swallow the sun god Ra as he crossed the sky.
Apep -- the Greeks called him Apophis -- personified death, destruction and chaos. His opponent was the goddess Ma'at, who represented all that was light and truth.
Now, a group of NASA scientists is hoping Ma'at will once again help humans ward off the harbinger of destruction.
The MAAT satellite -- Measurement and Analysis of Apophis Trajectory, a conveniently descriptive acronym -- is still just an idea. But if it's built, the modestly priced probe could help illuminate one of the solar system's most famous and most misunderstood asteroids.
A few months after its discovery in June 2004, asteroid 99942 Apophis was briefly thought to pose a serious threat to Earth in either 2029 or 2036. But further calculations showed it is unlikely to hit the planet, unless it passes through a gravitational "keyhole" that might send it swinging Earthward seven years after its initial visit.
This would be bad, explained David Morrison, director of the Lunar Science Institute at NASA's Ames Research Center at Moffett Field, Calif.
Apophis is about 1,000 feet across and roughly the size of a 25-story building. The 1908 Tunguska meteoroid, which caused a massive fireball and flattened a forest in Siberia, was about 10 times smaller and about 1,000 times weaker in terms of energy. "Where Tunguska would have destroyed a city, something like Apophis is rather worse. It would ruin your whole day," Morrison said. "That's big enough to destroy a state in the U.S., or a small country. It's not something that you would want to sit back and (ignore)."
Thankfully, Apophis is not likely to hit Earth, but it's worth studying because it comes so close and there are many other asteroids like it, Morrison said.
It does seem like a good starting point for missions to understand these sub-kilometer asteroids," he said.
As of Saturday, March 21, there were 6,163 known near-Earth asteroids, about 770 of which are a dangerous half-mile in diameter or wider, according to the Near Earth Object Office at NASA's Jet Propulsion Laboratory. Their paths around the sun occasionally bring them across Earth's orbit. With enough warning -- and so long as we know about the asteroid's existence, we'd have some warning -- humans could send a spacecraft to a threatening rock and kick it away by slightly altering its trajectory.
The MAAT probe would be designed to match Apophis' orbit and tell us if we need to move it. More cost studies are needed before NASA has a price tag, but Morrison said the mission is intended to be relatively inexpensive, around $100 million. It will piggyback onto a satellite going up to a geosynchronous orbit, about 18,000 to 22,000 miles above Earth, and continue until it hooks up with the asteroid. It won't land or crash, unlike previous asteroid missions such as Deep Impact, but it will shed some light on the space rock by flying in formation with it.
It would carry several cameras, a radio system and a laser range system to measure the distance between MAAT and Apophis so scientists can determine the asteroid's mass and trajectory. "If we ever face one that will hit us, the first question they are going to ask is its trajectory. It's only in Hollywood that asteroids change orbit. Once you determine the orbit carefully, then you can predict where it will be in the future," Morrison said.
Scientists hope a refined understanding of Apophis' path around the sun will erase lingering worries about its odds of striking Earth. "It would be nice to have a press conference and tell you for sure it's not going to happen," Morrison said.
Scientists' level of certainty has varied wildly since the asteroid was discovered in June 2004. That December, observations from some amateur astronomers set off alarms at JPL's Sentry asteroid-watching program. Around Christmas 2004 -- when most of the world was reacting to an Earth-based disaster, the Sumatra tsunami -- the odds of Apophis hitting Earth in 2029 peaked at 2.7 percent, a frightening statistical possibility.
The number was soon revised down after a flurry of observations; as of now, the chances of Apophis hitting Earth in 2029 are about 1 in 45,000. In 2029, it will pass within about 18,000 miles of Earth, well within the range of geosynchronous satellites, but scientists at JPL say its trajectory won't endanger the satellites.
That's where it gets interesting, however. Earth's gravity will dramatically affect Apophis' orbit, leaving scientists to estimate where it will end up next.
If Apophis passes at 18,893 miles above Earth, it will pass through a gravitational "keyhole" about half a mile wide, which would nudge it just enough to send it on a course for collision with Earth seven years later, on April 13, 2036. MAAT will provide more data to check these estimates and tell us whether we should do something to move Apophis from that keyhole using a solar sail, some added weight or a space tugboat of sorts. It's also a way to test a type of asteroid- tracker that might be really important someday.
We don't know exactly where Apophis is going to go, but it's very unlikely that it will end up on an impact trajectory," Morrison said. "But it is a prototype of the type of object that we might have to deal with."
Scientists at JPL are confident further observation will show Apophis will pass about 49 million miles from Earth on April 13, 2036, which happens to be Easter Sunday.
That date is one of many numerological coincidences that have helped make the asteroid famous: For one thing, Apophis is Near Earth Object 99942 -- 999 upside down is 666, the "number of the beast," a number associated with the end-times prophecy in the New Testament chapter Revelation. It is expected to pass Earth the first time on April 13, 2029 -- a Friday the 13th. What's more, 2 + 0 + 2 + 9 = 13.
Feeling unlucky yet? Maybe the probe named for goodness and light will be able to help illuminate this dark nomad of the sky.
Near-Earth Asteroid Talk
Interested in space rocks? Log on to a chat with NASA's asteroid hunters Wednesday, March 25, at 7:30 p.m. Eastern. Participants include Don Yeomans, manager of NASA's Near-Earth Object Office at the Jet Propulsion Laboratory, and two NEO office scientists, Steve Chesley and Paul Chodas. Join the discussion at http://www.ustream.tv/channel/nasajpl
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Fritz
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Re:Earth in near miss asteroid encounter
« Reply #5 on: 2009-03-26 20:02:35 » |
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"Things that go Bump in the Night" or "Splish, Splash, we're all having a Bath"
Cheers
Fritz
Impact Risk Tables
http://neo.jpl.nasa.gov/risk/
Source: ucsc
Author: Tim Stephens (831) 459-2495; stephens@ucsc.edu
Date: May 27, 2003
Massive tsunami sweeps Atlantic Coast in asteroid impact scenario for March 16, 2880
If an asteroid crashes into the Earth, it is likely to splash down somewhere in the oceans that cover 70 percent of the planet's surface. Huge tsunami waves, spreading out from the impact site like the ripples from a rock tossed into a pond, would inundate heavily populated coastal areas. A computer simulation of an asteroid impact tsunami developed by scientists at the University of California, Santa Cruz, shows waves as high as 400 feet sweeping onto the Atlantic Coast of the United States.
The researchers based their simulation on a real asteroid known to be on course for a close encounter with Earth eight centuries from now. Steven Ward, a researcher at the Institute of Geophysics and Planetary Physics at UCSC, and Erik Asphaug, an associate professor of Earth sciences, report their findings in the June issue of the Geophysical Journal International.
March 16, 2880, is the day the asteroid known as 1950 DA, a huge rock two-thirds of a mile in diameter, is due to swing so close to Earth it could slam into the Atlantic Ocean at 38,000 miles per hour. The probability of a direct hit is pretty small, but over the long timescales of Earth's history, asteroids this size and larger have periodically hammered the planet, sometimes with calamitous effects. The so-called K/T impact, for example, ended the age of the dinosaurs 65 million years ago.
"From a geologic perspective, events like this have happened many times in the past. Asteroids the size of 1950 DA have probably struck the Earth about 600 times since the age of the dinosaurs," Ward said.
Ward and Asphaug's study is part of a general effort to conduct a rational assessment of asteroid impact hazards. Asphaug, who organized a NASA-sponsored scientific workshop on asteroids last year, noted that asteroid risks are interesting because the probabilities are so small while the potential consequences are enormous. Furthermore, the laws of orbital mechanics make it possible for scientists to predict an impact if they are able to detect the asteroid in advance.
"It's like knowing the exact time when Mount Shasta will erupt," Asphaug said. "The way to deal with any natural hazard is to improve our knowledge base, so we can turn the kind of human fear that gets played on in the movies into something that we have a handle on."
Although the probability of an impact from 1950 DA is only about 0.3 percent, it is the only asteroid yet detected that scientists cannot entirely dismiss as a threat. A team of scientists led by researchers at NASA's Jet Propulsion Laboratory reported on the probability of 1950 DA crossing paths with the Earth in the April 5, 2002, issue of the journal Science.
"It's a low threat, actually a bit lower than the threat of being hit by an as-yet-undiscovered asteroid in the same size range over the same period of time, but it provided a good representative scenario for us to analyze," Asphaug said.
For the simulation, the researchers chose an impact site consistent with the orientation of the Earth at the time of the predicted encounter: in the Atlantic Ocean about 360 miles from the U.S. coast. Ward summarized the results as follows:
The 60,000-megaton blast of the impact vaporizes the asteroid and blows a cavity in the ocean 11 miles across and all the way down to the seafloor, which is about 3 miles deep at that point. The blast even excavates some of the seafloor. Water then rushes back in to fill the cavity, and a ring of waves spreads out in all directions. The impact creates tsunami waves of all frequencies and wavelengths, with a peak wavelength about the same as the diameter of the cavity. Because lower-frequency waves travel faster than waves with higher frequencies, the initial impulse spreads out into a series of waves.
"In the movies they show one big wave, but you actually end up with dozens of waves. The first ones to arrive are pretty small, and they gradually increase in height, arriving at intervals of 3 or 4 minutes," Ward said.
The waves propagate all through the Atlantic Ocean and the Caribbean. The waves decay as they travel, so coastal areas closest to the impact get hit by the largest waves. Two hours after impact, 400-foot waves reach beaches from Cape Cod to Cape Hatteras, and by four hours after impact the entire East Coast has experienced waves at least 200 feet high, Ward said. It takes 8 hours for the waves to reach Europe, where they come ashore at heights of about 30 to 50 feet.
Computer simulations not only give scientists a better handle on the potential hazards of asteroid impacts, they can also help researchers interpret the geologic evidence of past events, Ward said. Geologists have found evidence of past asteroid impact tsunamis in the form of inland sediment deposits and disturbed sediment layers in the seafloor that correlate with craters, meteorite fragments, and other impact evidence. An important feature of Ward's simulation is that it enabled him to calculate the speed of the water flows created by the tsunami at the bottom of the ocean--more than 3 feet per second out to distances of several hundred miles from the impact.
"That's like a raging river, so as these waves cross the ocean they're going to stir up the seafloor, eroding sediments on the slopes of seamounts, and we may be able to identify more places where this has happened," Ward said.
He added that the waves may also destabilize undersea slopes, causing landslides that could trigger secondary tsunamis. Ward has also done computer simulations of tsunamis generated by submarine landslides. He showed, for example, that the collapse of an unstable volcanic slope in the Canary Islands could send a massive tsunami toward the U.S. East Coast.
A tsunami warning system has been established for the Pacific Ocean involving an international effort to evaluate earthquakes for their potential to generate tsunamis. Ward said that asteroid impact tsunamis could also be incorporated into such a system.
"Tsunamis travel fast, but the ocean is very big, so even if a small or moderate-sized asteroid comes out of nowhere you could still have several hours of advance warning before the tsunami reaches land," he said. "We have a pretty good handle on the size of the waves that would be generated if we can estimate the size of the asteroid."
Planetary scientists, meanwhile, are getting a better handle on the risks of asteroid impacts. A NASA-led campaign to detect large asteroids in near-Earth orbits is about half way toward its goal of detecting 90 percent of those larger than 1 kilometer in diameter (the size of 1950 DA) by 2008.
"Until we detect all the big ones and can predict their orbits, we could be struck without warning," said Asphaug. "With the ongoing search campaigns, we'll probably be able to sound the 'all clear' by 2030 for 90 percent of the impacts that could trigger a global catastrophe."
Rogue comets visiting the inner solar system for the first time, however, may never be detected very long in advance. Smaller asteroids that can still cause major tsunami damage may also go undetected.
"Those are risks we may just have to live with," Asphaug said.
_____
Notes for reporters (movies, images, additional information):
A movie of the tsunami simulation can be viewed at http://es.ucsc.edu/~ward/1950-DA(5).mov.
Images can be downloaded from the web at http://www.ucsc.edu/news_events/download/.
Reporters may contact Ward at (831) 459-2480 or ward@uplift.ucsc.edu, and Asphaug at (831) 459-2260 or asphaug@es.ucsc.edu.
Additional information about the asteroid 1950 DA is available at:
http://neo.jpl.nasa.gov/1950da/.
The article by Ward and Asphaug in the Geophysical Journal International is available online at:
http://es.ucsc.edu/~ward/papers/gji_final_35N.pdf.
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Where there is the necessary technical skill to move mountains, there is no need for the faith that moves mountains -anon-
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Re:Earth in near miss asteroid encounter
« Reply #7 on: 2009-03-27 12:02:22 » |
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Quote from: DJ_dAndroid on 2009-03-27 01:51:51
I would hit it like the fist of an angry god.
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Now that's the way to own the anthropomorphism! 
:::Mo fistbumps DJ_dAndroid:::
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I will fight your gods for food,
Mo Enzyme
(consolidation of handles: Jake Sapiens; memelab; logicnazi; Loki; Every1Hz; and Shadow)
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Fritz
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Re:Earth in near miss asteroid encounter
« Reply #8 on: 2009-03-27 21:44:27 » |
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Quote:[Quote ]from: DJ_dAndroid on Today at 01:51:51
I would hit it like the fist of an angry god.
[Mo]Now that's the way to own the anthropomorphism!
:::Mo fistbumps DJ_dAndroid::: |
[Fritz]You young punks will be first to whine and complain when there is no planet left .... :::Fritz hi-5s himself:::
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Where there is the necessary technical skill to move mountains, there is no need for the faith that moves mountains -anon-
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