Author: Ian O'Neill

As computers become more advanced, the microprocessors inside them shrink in size and use less electrical current. These new, energy efficient chips can be crammed closer together, increasing the number of calculations that can be done per second, therefore making the computer more powerful. But even the mighty supercomputer has its Achilles heel: an increased sensitivity to interference from charged particles originating beyond your office. These highly energetic particles come from space and may cause critical hardware to miscalculate, possibly putting lives at risk.

Foreseeing this problem, microchip manufacturer Intel has begun devising ways to detect when a shower of charged particles may hit their chips, so when they do, calculations can be re-run to iron out any errors…

Cosmic rays originate from our Sun, supernovae and other unknown cosmic sources. Typically, they are very energetic protons that zip through space close to the speed of light. They could be so powerful that on impact with the upper atmosphere of the Earth it has been postulated that they may create micro black holes. Naturally these energetic particles can cause some damage. In fact, they may be a huge barrier to travelling beyond the safety of Earth’s magnetic field (the magnetosphere deflects most cosmic radiation, even astronauts in Earth orbit are well shielded), the health of astronauts will be severely damaged during prolonged interplanetary flight.

But what about on Earth, where we are protected from the full force of cosmic rays? Although a small portion of our annual radiation dose comes from cosmic rays (roughly 13%), they can have extensive effects over large volumes of the atmosphere. As cosmic rays collide with atmospheric molecules, a cascade of light particles is produced. This is known as an “air shower”. The billions of particles within the air shower from a single impact are often highly charged themselves (but of lesser energy than the parent cosmic ray), but the physics behind the air shower is beginning to grow in importance, especially in the realms of computing.

It seems computer microprocessor manufacturer Intel has been pondering the same question. They have just released a patent detailing their plans should a cosmic ray penetrate the atmosphere and hit one of their delicate microchips. The problem will come when computing becomes so advanced that the tiny chips may “misfire” when a comic ray impact event occurs. Should the unlucky chip be hit by a cosmic ray, a spike of electrical current may be exerted across the circuitry, causing a miscalculation.

This may sound pretty benign; after all, what’s one miscalculation in billions? Intel’s senior scientist Eric Hannah explains:

“All our logic is based on charge, so it gets interference. […] You could be going down the autobahn [German freeway] at 200 miles an hour and suddenly discover your anti-lock braking system doesn’t work because it had a cosmic ray event.” – Eric Hannah.

After all, computers are getting smaller and cheaper, they are being used everywhere including critical systems like the braking system described by Hannah above. As they are so small, many more chips can occupy computers, increasing the risk. Where a basic, one processor computer may only experience one cosmic ray event in several years (producing an unnoticed calculation error), supercomputers with tens of thousands of processors may suffer 10-20 cosmic ray events per week. What’s more, in the near future even humble personal laptops may have the computing power of today’s supercomputer; 10-20 calculation errors per week would be unworkable, there would be too high a risk of data loss, software corruption or hardware failure.

Orbital space stations, satellites and interplanetary spacecraft also come to mind. Space technology embraces advanced computing as you get far more processing power in a smaller package, reducing weight, size and cost. What happens when a calculation error occurs when a cosmic ray hits a satellite’s circuitry? A single miscalculation could spell the satellite’s fate. I’d dread to think what could happen to future manned missions to the Moon, Mars and beyond.

It is hoped that Intel’s plan may be the answer to this ominous problem. They want to manufacture a cosmic ray event tracker that would detect a cosmic ray impact, and then instruct the processor to recalculate the previous calculations from the point before the cosmic ray struck. This way the error can be purged from the system before it becomes a problem.

There will of course be many technical difficulties to overcome before a fast detector is developed; in fact Eric Hannah admits that it will be hard to say when such a device may become a practical reality. Regardless, the problem has been identified and scientists are working on a solution, at least it’s a start…

Source: BBC

They look like pockmarks caused by shrapnel from a huge explosion. Actually they are surface features on Mars as seen by the High Resolution Imaging Science Experiment (HiRISE) on board the Mars Reconnaissance Orbiter (MRO). But what are they? They’re not potholes formed by geological processes, they’re not openings to ancient lava tubes, they are impact craters… but not like any impact crater you’ve seen before…

Most meteorite impact craters are roughly circular. If they are fairly new, ejected debris will be obvious emanating from the impact site. However, recent images by the HiRISE instrument appear to show tiny impact craters, in a swarm, each looking like they have been chiselled roughly out of the Martian regolith (pictured left).

The area of the image covers roughly 0.5×1.5 kilometres (25cm/pixel; features down 85cm can be resolved) of a large outflow channel in the Chryse Planitia region. The craters are actually secondary impact craters caused by large chunks of Martian rock being thrown up into the air after an energetic impact from a meteorite. To give an idea of size, the largest craters are about 40 meters across, a little smaller than an Olympic-sized swimming pool. It is not clear where the primary impact crater is in relation to the debris craters in the full-resolution image.

There appears to be dark material inside these small craters, possibly from the debris digging into layered deposits of different minerals just below the surface. Ripples of sand and dust are also evident. As these small craters are quite shallow, they will fill up and level out with wind-blown material quickly, so these secondary craters are fairly young when compared with geological timescales.

Source: HiRISE mission site

Earth, four billion years ago, was a lifeless, hot and violent place. Not exactly a world where you’d expect life to form. But this was the scene where the first life-forming amino acids appeared. And how did this happen? According to new research, a lump of rock floating though space may have been irradiated by neutron star emissions, chemically altering amino acids hitching a ride on it. This rock then impacted the Earth and injected these altered chemicals into the desert wastes, possibly seeding the beginning of life on our planet… and this life was left-handed…

We’ve heard about this possibility before: life on Earth being seeded by some extra-terrestrial body, like a comet, meteorite or asteroid impact. In fact the prime reason for analysing comets and objects in the Oort Cloud (hovering around the outer reaches of our solar system) is to look for pre-life chemicals and organic compounds such as amino acids. Indeed, the discovery of organic compounds by the recent Cassini flyby of Saturn’s moon last month is another piece in the puzzle toward understanding the extent of life-giving chemicals on planets other than Earth.

Amino acids are a type of protein found in all life forms on Earth, it seems reasonable to search for the presence of these proteins on bodies other than our planet, possibly giving us more information about how life formed and where life came from.

There are two forms of amino acids, one left-handed and one right-handed, giving an indication of the orientation of the acid. For life to be seeded, these proteins must contain only one “chirality” (i.e. either left or right), it’s no good having mixed chirality.

At the 235th national meeting of the American Chemical Society, new research has been presented describing how our amino acid signature may have come from outer space. Ronald Breslow, a university professor at Columbia University points out that the vast majority of life on Earth has a “left chirality”. And his reason for this? The polarized light emitted from neutron stars many billions of years ago irradiated rocky bodies, with amino acid compounds on their surface, selectively destroying most of the “right-hand” acids. Although this theory may sound outlandish, it does give a possible reason for the prevalence of left-hand proteins in amino acids on Earth.

The irradiated meteorite will have impacted the Earth carrying amino acids with a dominance of left chirality which dropped into the “primordial soup”, evolving into the first forms of life. All life as we know it will have the same chirality as this soup of pre-biotic life.

“These meteorites were bringing in what I call the ‘seeds of chirality’ […] If you have a universe that was just the mirror image of the one we know about, then in fact, presumably it would have right-handed amino acids. That’s why I’m only half kidding when I say there is a guy on the other side of the universe with his heart on the right hand side.” – Ronald Breslow.

Breslow and his team simulated the events after such a meteorite hit the surface. As the left-hand dominated amino acids from space combined with existing amino acids (of mixed chirality) on Earth, the desert-like temperatures and a dash of water amplified the left-hand proteins, giving them dominance, thus sparking the basic building blocks of life. He argues that these acids were most likely brought to Earth via meteorite, and not chemically altered by radiation in-situ, “…the evidence that these materials are being formed out there and brought to us on meteorites is overwhelming,” said Breslow.

Source: Physorg.com

It’s a bit like trying to find a needle in a haystack when looking for a star in a galaxy. Although hard to do, astronomers using images from the Hubble Space Telescope (HST) are doing just that, trying to find stars before they explode as supernovae. In 2006, supernova SN 2006bc was spotted in spiral galaxy NGC 2397, so astronomers got to work, sifting through previous images taken by the HST. They found that star, in the rising stage of brightness as it exploded. Usually we don’t get to see this stage of a supernova, as we can’t predict which star is going to blow. But retracing years of HST observational data, scientists are able to piece together the cosmic forensic evidence and see the star before it died…

SN 2006bc was seen in the spiral galaxy NGC 2397, located nearly 60 million light years from the Milky Way, back in 2006. There was no warning or any indication that that star was going to blow in that galaxy (after all, there’s a lot out there), but Hubble’s Advanced Camera for Surveys (ACS) captured the galaxy after it happened. So astronomers watched the afterglow of the event. While a lot of good science can be done by analysing the remnants of a supernova, wouldn’t it be great to see a star before it explodes? Perhaps then we can analyse the emissions from an unstable star before it dies…

Predicting cosmic events is no new thing, and much effort is being put into various forecasting techniques. A few examples include:

• Solar radiation: The main focus for solar physicists is to predict “space weather” to help protect us against the dangerous onslaught of high energy particles (particularly solar flares).
• Detecting supernova neutrinos: An “early warning” system is already in place to detect the neutrinos that are blasted from a star’s core at the moment of a star’s collapse (leading to a supernova). The SuperNova Early Warning System (SNEWS) has been set up to detect these neutrinos.
• Gamma ray bursts (GRBs): The Polish “Pi of the Sky” GRB detector is an array of cameras looking out for optical flashes (or transients) in the night sky above the Chilean mountains. Combined with NASA’s Swift gamma ray observatory in orbit, the burst is detected, immediately signalling other observatories to watch the event.

The above examples usually detect the sudden event of a solar flare, GRB or surge of neutrinos right at the point of initiation. Fortunately for solar physicists, we have a vast amount of high-spatial and high-temporal resolution data about our closest star. Should a flare be launched, we can “rewind the tape” and see the location of flare initiation and work out the conditions before the flare was launched. From this, we are able to be better informed and possibly predict where the next flare will be launched from. Supernova astronomers aren’t so lucky. The cosmos is a big place after all, only a tiny proportion of the night sky has been observed in any great detail, and the chances that the same region has been imaged more than once at high resolution are few and far between.

Although the chances are slim, researchers from Queen’s University Belfast in Northern Ireland, led by Professor Stephen J. Smartt used Hubble Space Telescope (HST) images to “rewind the tape” before supernova SN 2006bc occurred. By confining their search for “pre-supernova” stars in local galaxies, there was a better chance of studying galaxies that have been imaged at high resolution and imaged more than once in the past. SN 2006bc turned out to be the perfect candidate.

The group has done this before. Of the six precursor stars discovered to date, Smartt’s team found five of them. From their analysis, it is hoped that the characteristics of a star before it dies can be worked out as the conditions for a supernova to occur is poorly understood.

After ten years of surveying, the group presented their discoveries of supernova precursor stars at this year’s National Astronomy Meeting 2008 in Belfast, last week. It appears that stars with masses as low as seven times the size of our Sun can explode as supernovae. They go on to hypothesise that the massive stars may not explode as supernovae and may just die through collapse and form as a black hole. The emission from such an event may be too faint to observe and the most energetic supernovae may be restricted to the smaller stars.

However, six supernova precursor stars are not a large number to make any big conclusions quite yet, but it is a big step in the right direction to better understand the mechanisms at work in a star just about to explode…

Source: ESA