7 May 2008

65-MILLION-YEAR-OLD ASTEROID IMPACT TRIGGERED A GLOBAL HAIL OF CARBON BEADS

The asteroid presumed to have wiped out the dinosaurs struck the Earth with such force that carbon deep in the Earth's crust liquefied, rocketed skyward, and formed tiny airborne beads that blanketed the planet, say scientists from the U.S., U.K., Italy, and New Zealand in this month's Geology.

The beads, known to geologists as carbon cenospheres, cannot be formed through the combustion of plant matter, contradicting a hypothesis that the cenospheres are the charred remains of an Earth on fire. If confirmed, the discovery suggests environmental circumstances accompanying the 65-million-year-old extinction event were slightly less dramatic than previously thought.

"Carbon embedded in the rocks was vaporized by the impact, eventually forming new carbon structures in the atmosphere," said Indiana University Bloomington geologist Simon Brassell, study coauthor and former adviser to the paper's lead author, Mark Harvey.

The carbon cenospheres were deposited 65 million years ago next to a thin layer of the element iridium -- an element more likely to be found in Solar System asteroids than in the Earth's crust. The iridium-laden dust is believed to be the shattered remains of the 200-km-wide asteroid's impact. Like the iridium layer, the carbon cenospheres are apparently common. They've been found in Canada, Spain, Denmark and New Zealand.

But the cenospheres' origin presented a double mystery. The cenospheres had been known to geologists only as a sign of modern times -- they form during the intense combustion of coal and crude oil. Equally baffling, there were no power plants burning coal or crude oil 65 million years ago, and natural burial processes affecting organic matter from even older ages -- such as coals from the 300-million-year-old Carboniferous Period -- had simply not been cooked long or hot enough.

"Carbon cenospheres are a classic indicator of industrial activity," Harvey said. "The first appearance of the carbon cenospheres defines the onset of the industrial revolution."

The scientists concluded the cenospheres could have been created by a new process, the violent pulverization of the Earth's carbon-rich crust.

Geologists do believe the Earth burned in spots as molten rock and super-hot ash fell out of the sky and onto flammable plant matter. But the charcoal-ized products of these fires only appear in some places on Earth, and are more often found near the asteroid impact site of Chicxulub Crater, just west of Mexico's Yucatan Peninsula. Some geologists had thought all carbon particles resulting from the impact was ash from global scale forest fires, but the present research strongly contradicts that assumption.

The scientists examined rock samples from eight marine locations in New Zealand, Italy, Denmark and Spain. They also examined carbon-rich particles from five non-marine locations in the U.S. and Canada. Following chemical and microscopic analysis, the researchers concluded the particles were carbon cenospheres, similar to the ones produced by industrial combustion.

The scientists also found that the farther the sample site was from the Chicxulub Crater, the smaller the cenospheres tended to be. That observation is consistent with the expectation that particles were produced by the asteroid impact, since once the particles are ejected, heavier particles should fall back to Earth sooner (and travel shorter distances) than lighter particles.

Last, the scientists estimated the total mass of carbon cenospheres ejected by the asteroid collision, assuming a global distribution, to be perhaps as much as 900 quadrillion kilograms. Whether or not the carbon cenospheres are truly ubiquitous, however, needs further corroboration.

"There are still clues to unravel about the events occurring around the time of the impact," Brassell said. "And there are aspects of the Earth's natural carbon cycle that we didn't previously consider."

Harvey is interested in the unique properties of the cenospheres themselves. "Perhaps we can generate and study carbon cenospheres to better understand them," he said. "We also need to look for the cenospheres in other parts of the world and also around the time of other extinction events."

5 May 2008

CANADIAN SATELLITE TO DETECT EARTH HITS

Canadian researchers are working on a tiny satellite that will alert the world to the potential of asteroid strikes.

"This is the first space-based asteroid-searching telescope," said Alan Hildebrand of the University of Calgary (Alberta), one of two principal scientists for the satellite.

He told the Canwest News Service the Near Earth Object Surveillance Satellite, set to be launched within two years is "the first space-based asteroid-searching telescope."

Once completed, the NEOSSat device will weigh only 135 pounds, and will be the size of a small suitcase, the report said.

"I think the most exciting thing about this mission is we are going to find asteroids that are accessible from our planet," Hildebrand said.

He said the mini-satellite would also help define celestial origins.

"We've been to the moon. There's always more you can do (there), but asteroids have so much more to teach us about the origins of the solar system," Hildebrand told the news agency.

5 May 2008

DID THE SOLAR SYSTEM BOUNCE AND KILL OFF THE DINOSAURS

The sun's movement through the Milky Way regularly sends comets hurtling into the inner solar system - coinciding with mass life extinctions on earth, a new study claims. Scientists at the Cardiff Centre for Astrobiology built a computer model of our solar system's movement and found that it "bounces" up and down through the plane of the galaxy.

As we pass through the densest part of the plane, gravitational forces from the surrounding giant gas and dust clouds dislodge comets from their paths. The comets plunge into the solar system, some of them colliding with the earth.

The Cardiff team found that we pass through the galactic plane every 35 to 40 million years, increasing the chances of a comet collision tenfold. Evidence from craters on Earth also suggests we suffer more collisions approximately 36 million years. Professor William Napier, of the Cardiff Centre for Astrobiology, said: "It's a beautiful match between what we see on the ground and what is expected from the galactic record."

The periods of comet bombardment also coincide with mass extinctions, such as that of the dinosaurs 65 million years ago. Our present position in the galaxy suggests we are now very close to another such period.

While the "bounce" effect may have been bad news for dinosaurs, it may also have helped life to spread. The scientists suggest the impact may have thrown debris containing micro-organisms out into space and across the universe.

Centre director Professor Chandra Wickramasinghe said: "This is a seminal paper which places the comet-life interaction on a firm basis, and shows a mechanism by which life can be dispersed on a galactic scale."

2 May 2008

COULD JUPITER WRECK THE SOLAR SYSTEM?

Written by Ian O'Neill

Scientists have expressed their concern that the Solar System may not be as stable as it seems. Happily orbiting the Sun, the eight planets (plus Pluto and other minor planets) appear to have a high degree of long-term gravitational stability. But Jupiter has a huge gravitational influence over its siblings, especially the smaller planets. It appears that the long-term prospects for the smallest planet are bleak. The huge gravitational pull of Jupiter seems to be bullying Mercury into an increasingly eccentric death-orbit, possibly flinging the cosmic lightweight into the path of Venus. To make things worse, there might be dire consequences for Earth…

Jupiter appears to be causing some planetary trouble. This gas giant orbits the Sun at a distance of approximately 5 AU (748 million km), that's five times further away from the Sun than the Earth. Although the distance may be huge, this 318 Earth-mass planet's gravitational pull is very important to the inner solar system planets, including tiny Mercury. Mercury orbits the Sun in an elliptical orbit, ranging between 0.47 AU (at aphelion) to 0.31 AU (at perihelion) and is only 0.055 Earth masses (that's barely five-times the mass of our Moon).

Running long-term simulations on the orbits of our Solar System bodies, scientists in France and California have discovered something quite unsettling. Jacques Laskar of the Paris Observatory, as well as Konstantin Batygin and Gregory Laughlin of the University of California, Santa Cruz have found that Jupiter's gravity may perturb Mercury's eccentric orbit even more. So much so their simulation predicts that Mercury's orbit may extend into the path of Venus; or it might simply fall into the Sun. The researchers formulate four possible scenarios as to what may happen as Mercury gets disturbed:

Mercury will crash into the Sun
Mercury will be ejected from the solar system altogether
Mercury will crash into Venus
Mercury will crash into Earth

The last option is obviously the worst case scenario for us, but all will be bad news for Mercury, the small planet's fate appears to be sealed. So what's the likelihood Mercury could crash into the Earth? If it did, the asteroid that most likely wiped out the dinosaurs will seem like a drop in the ocean compared with a planet 4880 km in diameter slamming into us. There will be very little left after this wrecking ball impact.

But here's the kicker: There is only a 1% chance that these gravitational instabilities of the inner Solar System are likely to cause any kind of chaos before the Sun turns into a Red Giant and swallows Mercury, Venus, Earth and Mars in 7 billion years time. So, no need to look out for death-wish Mercury quite yet… there's a very low chance that any of this will happen. But some good news for Mars; the researchers have also found that if the chaos does ensue, the Red Planet may be flung out of the Solar System, possibly escaping our expanding Sun.

These results will be published by Batygin and Laughlin will be published in The Astrophysical Journal.

17 April 2008

PLANETARY PROTECTION: HOW MUCH SHOULD WE SPEND TO ADDRESS NEO IMPACT RISK?

Seed Magazine, by Lee Billings

Until very recently, the devastating 1908 explosion of a space rock over the isolated Tunguska region of Siberia was thought to be a once-in-a-millennium event. Based on comparisons to nuclear weapon blast effects, many experts estimated the Tunguska object to be 50 to 100 meters. But new simulations by Mark Boslough at Sandia National Laboratories suggest the Tunguska object was much smaller than previously believed. And since smaller near-Earth objects (NEOs) are more common than larger ones, the implication is that the gap between such impacts may be centuries rather than millennia.

"Chances are we're not going to discover one of these before it hits," Boslough says, pointing out that the vast number of small NEOs far outweighs the capabilities of the few surveys currently seeking them. "The good news is most of the Earth is either sparsely populated or uninhabited, so the probability a city or populated area will be hit is small. The big ones, 1 kilometer or larger, are the ones we should worry about."

While space agencies, governments, and individuals worldwide work to develop new means to detect, and eventually prevent, an NEO disaster, the US government-though it provides the global majority of NEO research funding-is mostly paying lip-service to a risk that could threaten the survival of civilization. In 2005, the US Congress built off mandates from the 1990s, directing NASA to catalog 90 percent of potentially hazardous NEOs greater than 140 meters in diameter by the year 2020. Congress also asked NASA to study ways to deflect threatening NEOs. But burdened with completing the International Space Station and replacing the Space Shuttle fleet, NASA has yet to allot funds to the project. Stagnant science budgets also threaten the Arecibo radio telescope in Puerto Rico, the top facility for studying NEOs. Citing budgetary limitations, NSF announced last year it will defund Arecibo's operation after 2010.

"Most Americans have faith that the federal government is doing what's necessary to protect us against threats that could destroy our country or leave large numbers of Americans dead," says US Representative Dana Rohrabacher, who introduced legislation last December calling for NASA to devote more resources to NEO research. "The fact that we haven't even formulated what our reaction would be to a potential threat from space is disturbing, considering the magnitude of the risk involved. You'd think there would be a plan ready, but there isn't."

Increasingly, coordinated private efforts are working to fill the gap in Earth's NEO defenses. Motivated in part by the upcoming US presidential election, leading space scientists recently attended an invite-only workshop at Stanford University to discuss shifting NASA's priorities away from a return to the Moon and toward manned missions to NEOs. And the B612 Foundation, a group co-founded by Apollo astronaut Rusty Schweickart, is gathering funds to test deflection strategies on an NEO by 2015. Earlier this year, Microsoft alumni Bill Gates and Charles Simonyi donated a combined $30 million to the Large Synoptic Survey Telescope (LSST), keeping it on track for first light in 2014. One of LSST's chief missions is to detect and catalog NEOs. As for Arecibo, Jim Cordes, a Cornell astronomer who frequently works at the observatory, says that in the absence of government funding, a consortium of universities may have to step in to fund the facility's operations beyond 2010.

Schweickart summarized what's at stake in a prepared statement at a November 2007 Capitol Hill hearing, where NASA and Congress clashed over how to address the NEO threat: "If we live up to our responsibility, if we wisely use our amazing technology, and if we are mature enough, as a nation and as a community of nations, there may never again be a substantially damaging asteroid impact on the Earth. We have the ability to make ourselves safe from cosmic extinction. If we cannot manage to meet this challenge, we will, in my opinion, have failed to meet our evolutionary responsibility."

16 April 2008

APOPHIS RISK NOT INCREASED

First the story appeared on April 4 in Germany's 'leading' tabloid ("I have calculated the end of the world ... and NASA says, I'm right"), later in more serious papers ("Nico and the end of the world") - and today, thanks apparently to an AFP story where the writer hadn't found it necessary to check anything, it has taken off around the world. Alas: it's absolute nonsense! The claim is that a 13-year old German schoolbody "discovered" - while working on an entry for a major German science competition - that the 2036 impact probability of asteroid Apophis is not 1:45,000 as the NASA calculation says but actually 100 times higher. Because during the 2029 approach the asteroid would hit a geostationary satellite and be deflected into a much more dangerous orbit. The newspapers also claimed that this boy not only was awarded several prizes for his paper but that NASA had "conceded" that he got it right and they were wrong. We're all doomed, right?

Well, here's what NASA's NEO guru Don Yeomans said yesterday: "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."

And here's how one of the German scientists mentioned in the first story, celestial dynamics expert Frank Spahn from Potsdam University, explained events today: "I indeed had contact with this engaged boy - he asked me which perturbations/forces determine Apophis' orbit and especially during the close flybys. You know that I deal with kinetic theory & celestial mech. in the context of planetary rings, preplanetary disks etc. I explained him the 3 and 4 body problem and gravitational interactions in general. He did not tell me about his idea to consider a collision. This was in January or February. The next time when I heard of him was in the boulevard journal "Bild" - together with my name.

I asked him to meet me (last Friday), he told me about the asteroid - satellite collision thing (after I asked him how he calculated and "corrected" the NASA result). Then I showed him at the black board about the extremely small collision probability (frequency) with such an object. Seeing the arising problems I attended the set of [German TV news station] N24 and explained the leading responsible person that I appreciate the engagement of that young student but simultaneously I express that one has to mention the low probability of such a collision plus expressing that this is not a correction to NASA. The filming session went on and I had to leave for another meeting. The I saw yesterday that nonsens in TV - and I am shocked. By the way - I haven't seen that paper and the work sofar, Nico told me that his computer disk had a virus so that only hard copies are available which are with the referees of the contest at the moment. So - I do not know how he could have won the competition, obviously the referees were no experts."

Nor were the writers for the German newspapers or AFP - none of which bothered to ask NASA directly or just consult the impact risk page for Apophis. This is clearly the most used and abused Near Earth Asteroid in many years: Still called 2004 MN4 it briefly reached a record high impact probability for 2029 in late 2004 which quickly evaporated (as always in these cases - so far) when radar data nailed down its orbit in early 2005. And in the following months the remaining impact improbability for 2036 also continued to dwindle, to the present 1 in 45,000: You can follow the real science - and the triumph of radar astrometry - on this dedicated NASA website. Which certain Jugend Forscht judges and journalists should have consulted, too ...