Archive for the ‘comet’ Category

67p-jets
Instruments on the Rosetta spacecraft have detected compounds critical to life, including the amino acid glycine and the element phosphorus, in the shroud of gases surrounding Comet 67P/Churyumov-Gerasimenko

For the first time, scientists have directly detected a crucial amino acid and a rich selection of organic molecules in the dusty atmosphere of a comet, further bolstering the hypothesis that these icy objects delivered some of life’s ingredients to Earth.

The amino acid glycine, along with some of its precursor organic molecules and the essential element phosphorus, were spotted in the cloud of gas and dust surrounding Comet 67P/Churyumov-Gerasimenko by the Rosetta spacecraft, which has been orbiting the comet since 2014. While glycine had previously been extracted from cometary dust samples that were brought to Earth by NASA’s Stardust mission, this is the first time that the compound has been detected in space, naturally vaporized.

The discovery of those building blocks around a comet supports the idea that comets could have played an essential role in the development of life on early Earth, researchers said.

“With all the organics, amino acid and phosphorus, we can say that the comet really contains everything to produce life — except energy,” said Kathrin Altwegg of the University of Bern in Switzerland, the principal investigator for the Rosetta mission’s ROSINA instrument.

“Energy is completely missing on the comet, so on the comet you cannot form life,” Altwegg told Space.com. “But once you have the comet in a warm place — let’s say it drops into the ocean — then these molecules get free, they get mobile, they can react, and maybe that’s how life starts.”

Getting a glimpse

Glycine, one of the simplest amino acids, is usually bound up as a solid, which means it’s difficult to detect from afar, Altwegg said.

While scientists have searched for glycine through telescopes in star-forming regions of the sky, the newly reported detection marks the first sighting of the compound in space. In this case, the orbiting Rosetta was close enough to pick up the glycine released by the comet’s dust grains as they heated up in the sun.

The study is a powerful confirmation of earlier, earth-bound detections of life’s building blocks in comet and meteor material.

“We know the Earth was pretty heavily bombarded both with asteroidal material and cometary material,” said Michael A’Hearn, a comet researcher at the University of Maryland who was not involved in the new study.

“There have been various claims of amino acids in meteorites, but all of them have suffered from this problem of contamination on Earth. The Stardust [samples] — which are from a comet, not an asteroid — are probably the least susceptible to the terrestrial contamination problem, but even there the problem is severe,” A’Hearn told Space.com. “I think they [Stardust] really did have glycine, but this is a much cleaner detection in many ways.”

Cooking up life
Amino acids form the basis of proteins, which are complexly folded molecules that are critical to life on Earth. Altwegg’s team searched for other amino acids around the comet as well, but located only glycine — the only one that can form without liquid water (as in the frigid reaches of space).

The glycine probably didn’t form on the comet itself, Altwegg said, but rather in the broad stretches of dust and debris that made up the solar system before planetary bodies formed.

“The solar system was made out of material which formed in a disk, in a solar nebula,” Altwegg said. “In these clouds, it’s pretty cold, so the chemistry you do there is catalytic chemistry on the dust surfaces. And these very small dust grains [1 micron in size] are very good to lead to organic chemistry. This is also done in the lab.” Earth itself was far too hot for similar delicate amino acids to survive its formation, Altwegg said; only the smallest solar system bodies stayed cold.

So glycine formed during that time could have provided a boost to newly forming life if it was delivered to Earth by comets.

“It’s not that it couldn’t have formed on Earth — it certainly could — it’s just that it didn’t have to,” A’Hearn said. “Basically, the Earth got a head start.”

Other, more complex amino acids require liquid water, and so would have likely formed on Earth itself, Altwegg said. This idea is supported by the fact that Rosetta has not identified any amino acids other than glycine near Comet 67P.

Phosphorus is also vital to life as we know it. Among other things, the element is a key constituent of DNA and adenosine triphosphate (ATP), a molecule that stores the chemical energy used by cells.

See more at: http://www.space.com/33011-life-building-blocks-found-around-comet.html#sthash.47SrU6BY.dpuf

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.

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Polonnaruwa%20meteorite

On 29 December 2012, a fireball lit up the early evening skies over the Sri Lankan province of Polonnaruwa. Hot, sparkling fragments of the fireball rained down across the countryside and witnesses reported the strong odour of tar or asphalt.

Over the next few days, the local police gathered numerous examples of these stones and sent them to the Sri Lankan Medical Research Institute of the Ministry of Health in Colombo. After noticing curious features inside these stones, officials forwarded the samples to a team of astrobiologists at Cardiff University in the UK for further analysis.

The results of these tests, which the Cardiff team reveal today, are extraordinary. They say the stones contain fossilised biological structures fused into the rock matrix and that their tests clearly rule out the possibility of terrestrial contamination.

In total, Jamie Wallis at Cardiff University and a few buddies received 628 stone fragments collected from rice fields in the region. However, they were able to clearly identify only three as possible meteorites.

The general properties of these three stones immediately mark them out as unusual. One stone, for example, had a density of less than 1 gram per cubic centimetre, less than all known carbonaceous meteorites. It had a partially fused crust, good evidence of atmospheric heating, a carbon content of up to 4 per cent and contained an abundance of organic compounds with a high molecular weight, which is not unknown in meteorites. On this evidence, Wallis and co think the fireball was probably a small comet.

The most startling claims, however, are based on electron microscope images of structures within the stones (see above). Wallis and co say that one image shows a complex, thick-walled, carbon-rich microfossil about 100 micrometres across that bares similarities with a group of largely extinct marine dinoflagellate algae.

They say another image shows well-preserved flagella that are 2 micrometres in diameter and 100 micrometres long. By terrestrial standards, that’s extremely long and thin, which Wallis and co interpret as evidence of formation in a low-gravity, low-pressure environment.

Wallis and co also measured the abundance of various elements in the samples to determine their origin. They say that low levels of nitrogen in particular rule out the possibility of contamination by modern organisms which would have a much higher nitrogen content. The fact that these samples are also buried within the rock matrix is further evidence, they say.

Wallis and co are convinced that the lines of evidence they have gathered are powerful and persuasive. “This provides clear and convincing evidence that these obviously ancient remains of extinct marine algae found embedded in the Polonnaruwa meteorite are indigenous to the stones and not the result of post-arrival microbial contaminants,” they conclude.

There’s no question that a claim of this kind is likely to generate controversy. Critics have already pointed out that the stones could have been formed by lightning strikes on Earth although Wallis and co counter by saying there was no evidence of lightning at the time of the fireball and that in any case, the stones do not bear the usual characteristics of this kind of strike. What’s more, the temperatures generated by lightning would have destroyed any biological content.

Nevertheless, extraordinary claims require extraordinary evidence and Wallis and co will need to make their samples and evidence available to the scientific community for further study before the claims will be taken seriously.

If the paper is taken at face value, one obvious question that arises is where these samples came from. Wallis and co have their own ideas: “The presence of fossilized biological structures provides compelling evidence in support of the theory of cometary panspermia first proposed over thirty years ago,” they say.

This is an idea put forward by Fred Hoyle and Chandra Wickramasinghe, the latter being a member of the team who has carried out this analysis.

There are other explanations, of course. One is that the fireball was of terrestrial origin, a remnant of one of the many asteroid impacts in Earth’s history that that have ejected billions of tonnes of rock and water into space, presumably with biological material inside. Another is that the structures are not biological and have a different explanation.

Either way, considerably more work will have to be done before the claims from this team can be broadly accepted. Exciting times ahead!

http://www.technologyreview.com/view/512381/astrobiologists-find-ancient-fossils-in-fireball-fragments/

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.

The Ural Mountains were shaken by some pretty dramatic explosions on Friday, as a meteorite burst in midair and showered Russia with the remnants.

The Chelyabinsk region of Russia, in the Ural Mountains about 930 miles east of Moscow, was pelted by at least one meteorite on Friday, freaking out residents with bright streaks across the sky and loud, window-shaking explosions. No serious injuries have been reported from the blasts, and Russian authorities are providing slightly different explanations for what happened. The growing consensus is that a meteorite exploded about 32,000 feet in the air, scattering smaller chunks around the region. “Verified information indicates that this was one meteorite which burned up as it approached Earth and disintegrated into smaller pieces,” Russian Emergency Ministries official Elena Smirnykh tells Russia’s RIA Novosti.

 

A new comet has been discovered that is predicted to blaze incredibly brilliantly in the skies during late 2013. With a perihelion passage of less than two million kilometres from the Sun on 28 November 2013, current predictions are of an object that will dazzle the eye at up to magnitude —16. That’s far brighter than the full Moon. If predictions hold true then C/2012 S1 will certainly be one of the greatest comets in human history, far outshining the memorable Comet Hale-Bopp of 1997 and very likely to outdo the long-awaited Comet Pan-STARRS (C/2011 L4) which is set to stun in March 2013.

The new comet, named C/2012 S1 (ISON) was found by the International Scientific Optical Network (ISON) in Russia on 21 September when astronomers Vitali Nevski and Artyom Novichonok captured it on CCD images taken through a 0.4-metre reflector. Its near-parabolic orbit suggests that it has arrived fresh from the Oort Cloud, a vast zone of icy objects orbiting the Sun, pristine remnants of the formation of the Solar System.

C/2012 S1 currently resides in the northwestern corner of Cancer. At magnitude +18 it is too dim to be seen visually but it will be within the reach of experienced amateur astronomers with CCD equipment in the coming months as it brightens. It is expected to reach binocular visibility by late summer 2013 and a naked eye object in early November of that year. Northern hemisphere observers are highly favoured. Following its peak brightness in late November it will remain visible without optical aid until mid-January 2014.

Comet brightness predictions sometimes exceed their performance. Amateur astronomers of a certain age may remember the Comet Kohoutek hype of 1973 – not quite the ‘damp squib’ it has been portrayed, since it reached naked eye visibility! Even if C/2012 S1 takes on the same light curve as Kohoutek it is certain to be spectacular, quite possibly a once-in-a-civilisation’s-lifetime event.

http://www.astronomynow.com/news/n1209/25comet/