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Scientists find meteorite that came from innermost asteroid belt between Mars and Jupiter

September 19, 2009 By admin Leave a Comment

Washington, September 18 (ANI): In a very rare finding, scientists have discovered an unusual kind of meteorite in the Western Australian desert and have uncovered that it came from the innermost main asteroid belt between Mars and Jupiter.

Meteorites are the only surviving physical record of the formation of our Solar System.

However, information about where individual meteorites originated, and how they were moving around the Solar System prior to falling to Earth, is available for only a dozen of around 1100 documented meteorite falls over the past two hundred years.

According to Dr Phil Bland from the Department of Earth Science and Engineering at Imperial College London, the lead author of the study, “We are incredibly excited about our new finding. Meteorites are the most analysed rocks on Earth, but it’s really rare for us to be able to tell where they came from.”

The new meteorite, which is about the size of cricket ball, is the first to be retrieved since researchers from Imperial College London, Ondrejov Observatory in the Czech Republic, and the Western Australian Museum, set up a trial network of cameras in the Nullarbor Desert in Western Australia in 2006.

The researchers aim to use these cameras to find new meteorites, and work out where in the Solar System they came from, by tracking the fireballs that they form in the sky.

The new meteorite was found on the first day of searching using the new network, by the first search expedition, within 100m of the predicted site of the fall.

The meteorite appears to have been following an unusual orbit, or path around the Sun, prior to falling to Earth in July 2007, according to the researchers’ calculations.

The team believes that it started out as part of an asteroid in the innermost main asteroid belt between Mars and Jupiter.

It then gradually evolved into an orbit around the Sun that was very similar to Earth’s.

The new meteorite is also unusual because it is composed of a rare type of basaltic igneous rock.

According to the researchers, its composition, together with the data about where the meteorite comes from, fits with a recent theory about how the building blocks for the terrestrial planets were formed.

This theory suggests that the igneous parent asteroids for meteorites like today’s formed deep in the inner Solar System, before being scattered out into the main asteroid belt.

Asteroids are widely believed to be the building blocks for planets like the Earth, so the new finding provides another clue about the origins of the Solar System. (ANI)

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Jupiter made comet its temporary moon for 12 years in mid-20th century

September 14, 2009 By admin Leave a Comment

Washington, September 14 (ANI): An international team of astronomers has discovered that Jupiter had captured the comet 147P/Kushida-Muramatsu as its temporary moon in the mid-20th century, in an irregular orbit for about twelve years.

There are only a handful of known comets where this phenomenon of temporary satellite capture has occurred and the capture duration in the case of Kushida-Muramatsu, which orbited Jupiter between 1949 and 1961, is the third longest.

The phenomenon was detected by an international team led by Dr. Katsuhito Ohtsuka that modeled the trajectories of 18 “quasi-Hilda comets”, objects with the potential to go through a temporary satellite capture by Jupiter that results in them either leaving or joining the “Hilda” group of objects in the asteroid belt.

Most of the cases of temporary capture were flybys, where the comets did not complete a full orbit.

However, Dr. Ohtsuka’s team used recent observations tracking Kushida-Muramatsu over nine years to calculate hundreds of possible orbital paths for the comet over the previous century.

In all scenarios, Kushida-Muramatsu completed two full revolutions of Jupiter, making it only the fifth captured orbiter to be identified.

According to Dr. David Asher, “Our results demonstrate some of the routes taken by cometary bodies through interplanetary space that can allow them either to enter or to escape situations where they are in orbit around the planet Jupiter.”

Asteroids and comets can sometimes be distorted or fragmented by tidal effects induced by the gravitational field of a capturing planet, or may even impact with the planet.

The most famous victim of both these effects was comet D/1993 F2 (Shoemaker-Levy 9), which was torn apart on passing close to Jupiter and whose fragments then collided with that planet in 1994.

Previous computational studies have shown that Shoemaker-Levy 9 may well have been a quasi-Hilda comet before its capture by Jupiter.

“Fortunately for us Jupiter, as the most massive planet with the greatest gravity, sucks objects towards it more readily than other planets and we expect to observe large impacts there more often than on Earth,” said Dr. Asher.

“Comet Kushida-Muramatsu has escaped from the giant planet and will avoid the fate of Shoemaker-Levy 9 for the foreseeable future”, he added. (ANI)

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NASA all set to launch infrared eye to hunt for dark asteroids

September 3, 2009 By admin Leave a Comment

Sydney, September 3 (ANI): NASA is preparing to launch an infrared telescope that will hunt down dark asteroids that have slipped beneath our radar.

According to a report by ABC Science, the Wide-field Infrared Survey Explorer (WISE) spacecraft recently arrived at Vandenberg Air Force Base in California ahead of its launch later this year.

With a quartet of infrared sensors and a wide view, WISE is designed to survey the whole sky in infrared light.

It’s not the first telescope to do so, but scientists expect WISE’s observations will be 500 times sharper than a survey conducted in 1980s by IRAS, the Infrared Astronomical Satellite, according to astronomer Martin Cohen of the University of California at Berkeley.

The data will be complied into an all-sky infrared atlas, a tome that is expected to include about 300 million objects, including around 100,000 asteroids.

Many of the asteroids seen by WISE will be known objects.

Scientists hope to use the new observations to nail down details, such as an asteroid’s diameter and surface reflectivity.

“With ground-based scopes, it’s just a point source. You can’t tell size directly,” said University of Texas astronomer Dr Robert McMillan who leads Spacewatch, an asteroid-survey project.

“A big object that is dark and a small object that is bright are going to look like they have the same brightness,” he added.

The solar system contains several million asteroids, most of which reside in the main asteroid belt between Mars and Jupiter.

About 7000 asteroids have been identified that cross or come close to Earth’s orbit.

WISE will be able to spot asteroids emitting heat due to direct exposure from the Sun, as opposed to visible-light searches that find asteroids that are reflecting sunlight.

“Those are two different physical effects,” said McMillan. “An asteroid that has very dark colour in invisible light is going to get heated up more, just like a black car in a parking lot is going to get heated up more than a white car,” he added.

Scientists hope to get enough positioning information to follow up targets with ground-based observations.

McMillan expects that WISE will discover a few hundred new asteroids.

The information will be folded into ongoing surveys to map asteroids that could impact Earth and cause widespread damage.

Other WISE targets include brown dwarfs, which are Jupiter-sized stars that never got their nuclear fusion engines running, and ultra-luminous galaxies, which pump out the equivalent of about 1000 Sun-sized stars every year. (ANI)

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Comets, not asteroids, scarred Moon’s face about 4 billion years ago

July 29, 2009 By admin Leave a Comment

London, July 28 (ANI): A new study of ancient rocks in Greenland has suggested that icy comets – not rocky asteroids – launched a dramatic assault on the Earth and moon around 3.85 billion years ago, thus causing the lunar surface to become scarred.

“We can see craters on the moon’s surface with the naked eye, but nobody actually knew what caused them – was it rocks, was it iron, was it ice?” Uffe Grae Jorgensen, an astronomer at the Niels Bohr Institute in Copenhagen, Denmark, told New Scientist.

“It’s exciting to find signs that it was actually ice,” he said.

Evidence suggests that the Earth and moon had both formed around 4.5 billion years ago.

But, almost all the craters on the moon date to a later period, the “Late Heavy Bombardment” 3.8 to 3.9 billion years ago, when around 100 million billion tonnes of rock or ice crashed onto the lunar surface.

To find out whether asteroids or comets were the main culprits for the bombardment, Jorgensen decided to measure levels of the element iridium in ancient terrestrial rocks.

Iridium is rare on the Earth’s surface because almost all of it bound to iron and sank into the Earth’s core soon after the planet had formed. But iridium is relatively common in comets and meteorites.

His team calculated the amount of iridium that asteroids would leave on the Earth and moon compared to comets.

Because comets have more volatile elements and higher impact speeds due to their more elongated orbits around the sun, they would create giant plumes on impact, allowing more iridium to escape into space than during asteroid impacts.

The team predicted that asteroid bombardment would leave iridium levels of 18,000 and 10,000 parts per trillion in rocks on the Earth and moon respectively, while the same figures for comet bombardment would be about 130 and 10.

Ancient moon rocks returned by NASA’s Apollo missions have already confirmed that the lunar iridium levels are 10 parts per trillion or less.

To find out the terrestrial value, Jorgensen’s team sampled some of the world’s oldest rocks from Greenland, aged 3.8 billion years, and asked a Japanese laboratory to assess their iridium levels more accurately than ever before.

They contained iridium levels of 150 parts per trillion, which strongly suggests comets, rather than asteroids, caused the violent bombardment. (ANI)

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Space rock yields important “ingredient in kitchen” on Earth before life began

May 27, 2009 By admin Leave a Comment

London, May 27 (ANI): Scientists have found formic acid, a molecule implicated in the origins of life, has been found at record levels on a meteorite that fell into the Tagish Lake in Canada in the year 2000.

According to a report by BBC News, cold temperatures on the lake prevented the volatile chemical from dissipating quickly.

The researchers told a meeting of the American Geophysical Union that the formic acid was extraterrestrial.

Formic acid is one of a group of compounds dubbed “organics”, because they are rich in carbon.

“We are lucky that the meteorite was untouched by humans hands, avoiding contamination by organic compounds that we have on our fingers,” said Dr Christopher Herd, the curator of the University of Alberta’s meteorite collection.

Samples of the meteorite, totalling 850 grams, were collected from Tagish Lake in Canada.

The scientists found levels of formic acid four times higher than had previously been recorded on a meteorite.

“This has for a while been overlooked as we concentrated predominantly on the Murchison meteorite, but now we’ve got another fresh sample and we can start to analyze a different portion of the asteroid belt and therefore a different portion of the Solar System,” said Mark Sephton, a meteorite and geochemistry professor at Imperial College London.

The particular types, or isotopes, of hydrogen that are found in the formic acid show that it most likely formed in the cold regions of space before our Solar System existed.

On Earth, formic acid is commonly found in the stings of insects such as ants, but Professor Sephton said that it is likely to have been an important “ingredient in the kitchen” on Earth before life began.

The acid is known to act as a “reducing agent” – acting as a magnet for oxygen atoms during chemical reactions – and facilitate the conversion of some amino acids into others.

It may also be implicated in the transformation of the more primitive RNA into DNA.

Only one of the four “nucleobases” that make up RNA and DNA is different between the two: uracil is present in RNA while thymine takes its place in DNA.

Professor Sephton’s team found uracil in the Murchison meteorite, but no measurable amount of thymine.

However, formic acid is known to help along the reaction that converts the uracil into thymine.

“The reaction is one of the ways in which you can take some simple molecules and increase the chemical diversity of the pool of pre-biotic molecules,” said Professor Sephton. (ANI)

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Asteroids may have boosted life on Earth 3.9 billion years ago

May 21, 2009 By admin Leave a Comment

Washington, May 21 (ANI): A new study has indicated that the bombardment of Earth by asteroids 3.9 billion years ago may have enhanced early life rather then wipe it out.

The study, by University of Colorado at Boulder researchers, determined that the bombardment of Earth nearly 4 billion years ago by asteroids as large as the US state of Kansas would not have had the firepower to extinguish potential early life on the planet and may even have given it a boost.

Impact evidence from lunar samples, meteorites and the pockmarked surfaces of the inner planets paints a picture of a violent environment in the solar system during the Hadean Eon 4.5 to 3.8 billion years ago, particularly through a cataclysmic event known as the Late Heavy Bombardment about 3.9 million years ago.

Although many believe the bombardment would have sterilized Earth, the new study shows it would have melted only a fraction of Earth’s crust, and that microbes could well have survived in subsurface habitats, insulated from the destruction.

“These new results push back the possible beginnings of life on Earth to well before the bombardment period 3.9 billion years ago,” said CU-Boulder Research Associate Oleg Abramov.

“It opens up the possibility that life emerged as far back as 4.4 billion years ago, about the time the first oceans are thought to have formed,” he added.

The researchers used data from Apollo moon rocks, impact records from the moon, Mars and Mercury, and previous theoretical studies to build three-dimensional computer models that replicate the bombardment.

Abramov and CU-Boulder geological sciences Professor Stephen Mojzsis plugged in asteroid size, frequency and distribution estimates into their simulations to chart the damage to the Earth during the Late Heavy Bombardment, which is thought to have lasted for 20 million to 200 million years.

The 3-D models allowed Abramov and Mojzsis to monitor temperatures beneath individual craters to assess heating and cooling of the crust following large impacts in order to evaluate habitability.

The study indicated that less than 25 percent of Earth’s crust would have melted during such a bombardment.

“Even under the most extreme conditions we imposed, Earth would not have been completely sterilized by the bombardment,” said Abramov.

Instead, hydrothermal vents may have provided sanctuaries for extreme, heat-loving microbes known as “hyperthermophilic bacteria” following bombardments, said Mojzsis.

Even if life had not emerged by 3.9 billion years ago, such underground havens could still have provided a “crucible” for life’s origin on Earth, Mojzsis added. (ANI)

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Comets may have provided key ingredients for life on Earth

May 2, 2009 By admin Leave a Comment

Tel Aviv, April 29 (ANI): A new study by researchers at Tel Aviv University in Israel has suggested that comets might have provided the elements for the emergence of life on our planet.

While investigating the chemical make-up of comets, Professor Akiva Bar-Nun of the Department of Geophysics and Planetary Sciences at Tel Aviv University found they were the source of missing ingredients needed for life in Earth’s ancient primordial soup.

“When comets slammed into the Earth through the atmosphere about four billion years ago, they delivered a payload of organic materials to the young Earth, adding materials that combined with Earth’s own large reservoir of organics and led to the emergence of life,” said Professor Bar-Nun.

It was the chemical composition of comets that allowed them to kickstart life, he added.

Using a one-of-a-kind machine built at Tel Aviv University, researchers were able to simulate comet ice, and found that comets contain ingredients necessary for providing the basic nutrients of life.

Specifically, Prof. Bar-Nun looked at the noble gases Argon, Krypton and Xenon, because they do not interact with any other elements and are not destroyed by Earth’s oxygen.

These elements have maintained stable proportions in the Earth’s atmosphere throughout the lifetime of the planet, he explained.

“Now, if we look at these elements in the atmosphere of the Earth and in meteorites, we see that neither is identical to the ratio in the sun’s composition. Moreover, the ratios in the atmosphere are vastly different than the ratios in meteorites which make up the bulk of the Earth,” said Bar-Nun.

“So we need another source of noble gases which, when added to these meteorites or asteroid influx, could change the ratio. And this came from comets,” he added.

During the comets’ formation, the porous ice trapped gases and organic chemicals that were present in outer space.

“The pattern of trapping of noble gases in the ice gives a certain ratio of Argon to Krypton to Xenon, and this ratio – together with the ratio of gases that come from rocky bodies – gives us the ratio that we observe in the atmosphere of the Earth,” said Bar-Nun.

Thus, the arrival on Earth of comets and asteroids led to the necessary ratio of materials for organic life, “which eventually were dissolved in the ocean and started the long process leading to the emergence of life on Earth,” he added. (ANI)

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Asteroids age quickly because of a ‘sun tan’

April 23, 2009 By admin Leave a Comment

Munich, April 23 (ANI): A new study has revealed that asteroid surfaces age and redden much faster than previously thought – in less than a million years, all thanks to solar winds.

“Asteroids seem to get a ‘sun tan’ very quickly,” said lead author Pierre Vernazza. “But not, as for people, from an overdose of the Sun’s ultraviolet radiation, but from the effects of its powerful wind,” he added.

It has long been known that asteroid surfaces alter in appearance with time.

The observed asteroids are much redder than the interior of meteorites found on Earth, but the actual processes of this “space weathering” and the timescales involved were controversial.

Thanks to observations of different families of asteroids using ESO’s New Technology Telescope at La Silla and the Very Large Telescope at Paranal, as well as telescopes in Spain and Hawaii, Vernazza’s team have now solved the puzzle.

When two asteroids collide, they create a family of fragments with “fresh” surfaces.

The astronomers found that these newly exposed surfaces are quickly altered and change color in less than a million years – a very short time compared to the age of the Solar System.

“The charged, fast moving particles in the solar wind damage the asteroid’s surface at an amazing rate,” said Vernazza.

Unlike human skin, which is damaged and aged by repeated overexposure to sunlight, it is, perhaps rather surprisingly, the first moments of exposure (on the timescale considered) – the first million years – that causes most of the aging in asteroids.

By studying different families of asteroids, the team has also shown that an asteroid’s surface composition is an important factor in how red its surface can become.

After the first million years, the surface “tans” much more slowly. At that stage, the color depends more on composition than on age.

Moreover, the observations reveal that collisions cannot be the main mechanism behind the high proportion of “fresh” surfaces seen among near-Earth asteroids.

Instead, these “fresh-looking” surfaces may be the results of planetary encounters, where the tug of a planet has “shaken” the asteroid, exposing unaltered material.

Thanks to these results, astronomers will now be able to understand better how the surface of an asteroid, which often is the only thing we can observe, reflects its history. (ANI)

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“Noise” from space may help reveal mass of near-Earth asteroids

April 5, 2009 By admin Leave a Comment

Washington, April 4 (ANI): Planetary scientists are all set to turn “noise” from the data obtained by NASA/ESA LISA satellites’ mission into useful information about the mass of near-Earth asteroids.

LISA is on a mission to detect gravitational waves – a warping of the space/time continuum that scientists hope to see directly for the first time.

Slated for launch no earlier than 2018, LISA will include three satellites connected by laser beams. The distance between the satellites should change as a gravitational wave passes.

Einstein’s General Theory of Relativity predicts that gravitational waves from exploding stars or colliding black holes ripple across the universe, causing other bodies to wobble like driftwood in a motorboat’s wake.

In 2006, planetary scientists realized that Near Earth Asteroids (NEAs) also would make the spacecraft wobble as they passed nearby, creating a distinct signature in the data being collected.

Pasquale Tricarico, a scientist at the Tucson-based Planetary Science Institute, expanded on that work to predict the number of asteroid encounters LISA can expect and how those encounters can be used to determine the mass of passing asteroids.

According to Tricarico, LISA can expect to see one or two known near-Earth asteroids a year, and a total of around ten during the expected mission lifetime.

When an encounter with a known asteroid shows up in the data, scientists will already know its trajectory.

“So from the signal, we can indirectly measure the asteroid’s mass because that’s the only uncertainty in the equation,” Tricarico said.

“These mass measurements are important because we only know the mass of asteroids that have been visited by spacecraft or the mass of a few binary asteroids observed from Earth,” he added.

“We always wonder about the porosity, the density, and this will give us measurements from additional asteroids,” he explained.

If a known asteroid passes one of the satellites and doesn’t leave a signature, “that allows us to put an upper limit on the mass of that asteroid,” Tricarico added.

Tricarico also has predicted the number of potential encounters with smaller, unknown NEAs.

If LISA starts detecting five asteroids a year instead of two or three, this could modify theories concerning the distribution of sizes in the NEA population. (ANI)

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A large size and a fast bite made some fish go extinct 65 million years ago

March 29, 2009 By admin Leave a Comment

Washington, March 27 (ANI): A new study has unraveled why certain fishes went extinct 65 million years ago, attributing the reason of their decline to a large size and a fast bite.

Today, those same features characterize large predatory bony fishes, such as tuna and billfishes, that are currently in decline and at risk of extinction themselves, according to Matt Friedman, author of the study and a graduate student in evolutionary biology at the University of Chicago.

“The same thing is happening today to ecologically similar fishes,” he said. “The hardest hit species are consistently big predators,” he added.

Studies of modern fishes demonstrate that large body size is linked to large prey size and low rates of population growth, while fast-closing jaws appear to be adaptations for capturing agile, evasive prey-in other words, other fishes.

The fossil record provides some remarkable evidence supporting these estimates of function: fossil fishes with preserved stomach contents that record their last meals.

When an asteroid struck the earth at the end of the Cretaceous about 65 million years ago, the resultant impact clouded the earth in soot and smoke.

This blocked photosynthesis on land and in the sea, undermined food chains at a rudimentary level, and led to the extinction of thousands of species of flora and fauna, including dinosaurs.

Scientists had speculated that during that interval large predatory fishes might have been more likely than other fishes to go extinct because they tended to have slowly increasing populations, live more spread out, take longer to mature, and occupy precarious positions at the tops of food chains.

Today, ecologically similar fishes appear to be the least able to rebound from declining numbers due to overfishing.

To build the database he needed to test this prediction, Friedman traveled around the world measuring the body size and jaw bones of 249 genera of fossil fishes that lived during the late Cretaceous.

These kinds of direct measurements are possible in fossil fishes because many are represented by complete, articulated individuals.

This is unlike the fossil record of most other vertebrates, where bones, teeth and other parts of the skeleton are often scattered and found in isolation.

This study is the first to test this theory with hard data and to quantify the relationship between body size, jaw function and vulnerability of fishes during the Cretaceous extinction, according to Friedman.

“Anyway you sliced it, the data showed that if you were a big fish with a fast bite you were toast,” he said. (ANI)

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Life may have survived Earth’s early pounding 3.9 billion years ago

March 11, 2009 By admin Leave a Comment

London, March 11 (ANI): A new analysis has suggested that microbes living deep underground could have survived the massive barrage of impacts that blasted the Earth 3.9 billion years ago.

This means that today’s life might be descended from microbes that arose as far back as 4.4 billion years ago, when the oceans formed.

Around 3.9 billion years ago, shifts in the orbits of the gas giant planets are thought to have disrupted other objects in the solar system, sending many hurtling into the inner planets.

Geologists call that time the Hadean Eon, and thought its fiery hell of impacts would have sterilised the Earth.

But, according to a report in New Scientist, a new study by Oleg Abramov and Steve Mojzsis of the University of Colorado in Boulder suggests hardy life-forms could have survived if they were buried underground.

Using a computer model, they sent 200 million billion tonnes of mass – in rocks with the same mass distribution as those in today’s asteroid belt – slamming into the planet.

The biggest impacts would have done the most damage – a 500-kilometre-wide blockbuster would have spread a 350-metre-deep layer of 1200 degrees Celsius ejecta over the planet.

Yet, heat from the impacts would not have penetrated very deeply into the underlying solid crust.

The layer heated to the sterilization point, about 110 degrees C, would be only about 300 meters thick.

High-temperature ‘extremophile’ microbes, like those in the hot springs of Yellowstone National Park, US, would have survived at greater depths, down to their limit of about 4 km.

Moreover, the impacts might have helped provide a refuge for these heat-loving microbes by creating cracks in the rocky crust that water could flow into.

As to how far back could life have originated, the oldest isotopic evidence of life comes from rocks that formed 3.83 billion years ago, soon after the “late heavy bombardment” that battered the planet in the Hadean period.

But, heat-loving microbes appear to be among the Earth’s earliest life-forms, and may have developed as early as 4.4 billion years ago.

That’s when the hot young Earth, whose top few hundred kilometers had probably been vaporized 100 million years before, in the impact that formed the Moon, would have cooled enough for seas to form.

According to Mojzsis, “For all intents and purposes, life could have started 4.4 billion years ago, and the late heavy bombardment pruned, rather than frustrated, life.” (ANI)

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