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Science News Digest – 3rd December 2012

In the science news this week, frozen organic material found on Mercury, bread that can stay fresh for 60 days, hope for the giant tortoise, and finally… Pacman is found on another of Saturn’s moons.

Messenger reveals more of Mercury’s secrets

It’s probably one of the last places in the Solar System that you would expect to see ice, but NASA’s Messenger spacecraft has revealed that in the permanently shadowed craters of Mercury that is precisely what you find.

However, even more astonishing was the discovery of frozen organic material, reported the Guardian.

"It's not something we expected to see, but then of course you realise it kind of makes sense because we see this in other places", such as icy bodies in the outer solar system and in the nuclei of comets, the planetary scientist David Paige of the University of California, Los Angeles, told Reuters.

The Messenger spacecraft has been orbiting the tiny planet for the past two years, and has been collecting data by bouncing laser beams off the surface, counting particles in the planet’s thin atmosphere, and measuring gamma rays.

This latest discovery is the result of a year of painstaking work, based on computer models, experiments and deduction.

"The explanation that seems to fit all the data is that it's organic material," said the lead Messenger scientist Sean Solomon, of Columbia University in New York.

Paige added: "It's not just a crazy hypothesis. No one has got anything else that seems to fit all the observations better."

It’s likely that the organic material piggybacked on ice from comets or asteroids aeons ago.

The ice would have vapourised, and then re-solidified in the cold, dark craters on the planet’s surface.

Scientists do not believe that Mercury has ever been suitable for harbouring life, but the discovery of organics on the surface could be a clue into the origins of how life evolved on our own planet.

"Finding a place in the inner solar system where some of these same ingredients that may have led to life on Earth are preserved for us is really exciting," Paige said.

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Microwave technique that keeps bread fresh for 60 days

A new technique has been developed in the US that can make bread stay mould-free for 60 days, reported the BBC.

The company who have pioneered the process use a sophisticated microwave array that kills the mould spores which cause the problem.

The technique can also be used for other fresh foods, such as meat, fruit and vegetables.

The company believe that this technique could help dramatically reduce the amount of food waste in developed countries. Currently, the average American family throws away 40% of the food they purchase – which adds up to $165bn (£102bn) every year.

One of the major culprits is bread. As loaves are normally wrapped in plastic, this provides a perfect breeding ground for Rhizopus stolonifer – the fungus that leads to mould.

The researchers at the US company, called Microzap, originally built the microwave array to kill bacteria, such as MRSA and salmonella, but found that it had the added bonus of killing the mould spores in bread in around 10 seconds.

"We treated a slice of bread in the device, we then checked the mould that was in that bread over time against a control, " explained the CEO of the company, Don Stull.

"And at 60 days it had the same mould content as it had when it came out of the oven."

The array uses the same technology as you would find in your microwave at home, and there has already been interest shown by major bread manufacturers.

"We introduce the microwave frequencies in different ways, through a slotted radiator. We get a basically homogeneous signal density in our chamber - in other words, we don't get the hot and cold spots you get in your home microwave," said Stull.

However, the major setback may well be the public’s reaction to the bread. But Stull believes that if the feel and look of the zapped bread is the same as what we are used to – except that it stays that way for longer – then consumers will come around to the idea.

He also argues that if anything it could improve the taste of bread, as manufacturers currently use a number of preservatives in order to fight against the spread of mould. However, this means they also need to add a number of chemicals to the dough in order to mask the taste of the added preservatives.

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It’s not all over for the giant tortoise

Earlier this year, George the giant tortoise, who was the last of his sub-species, died. Although this marked the end of the Pinta Island tortoises, there has been much more encouraging news from one of the neighbouring islands, where a related sub-species has been saved from the brink of extinction, reported New Scientist.

The giant tortoise population on Espanola Island in the Galapagos Islands was just 14 in 1971. The tortoises reached this all-time low due to a number of factors, partly because so many were killed and eaten, but also because of the introduction of non-native species, like goats, which destroy the tortoises’ habitat.

"Goats are very problematic," says Michel Milinkovitch at the University of Geneva, Switzerland. "They eat everything."

Conservationists took drastic measures in 1971 and moved all the tortoises they could find to a neighbouring island, Santa Cruz, to breed in captivity. They were later joined by another tortoise from San Diego Zoo in California.

In the meantime, Espanola was cleared of goats allowing the tortoises’ natural habitat to flourish once again. Since the start of the scheme, over 1700 tortoises have been reintroduced to the island.

However, the true measure of success would be if the tortoises survived and bred when left to their own devices on the island. Because all the tortoises came from a population of just 15, genetic diversity was bound to be low. This can cause problems, as inbred animals tend to die younger, have poor fertility and are often more vulnerable to environmental changes.

However, following a genetic analysis of the tortoises on the island in 2007, the researchers have shown that roughly a quarter of the animals on the island are native, i.e. have been born on the island and not at the sanctuary on Santa Cruz.

"We're really excited," says Milinkovitch. "The habitat is restored, the species is thriving and the animals are breeding happily. We can now safely say that the species is saved."

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And finally…

Pacman seen on Saturn’s moons

A thermal image of one of Saturn’s moons, Tethys, has revealed a heat signature that has an uncanny resemblance to the eighties arcade game character Pac-Man, reported the BBC.

The image is not the first time that a Pac-Man shape has been spotted on a Saturnian moon. In 2010, a similar thermal image was revealed on the moon, Mimas.

It has been suggested that the effect could be caused by high-energy electrons bombarding the side of the moon that faces the direction of orbital travel. This then compacts the surfaces, making it hard and icy, and therefore it won’t heat or cool as quickly as the unaffected surface.

"Finding a second Pac-Man in the Saturn system tells us that the processes creating these 'Pac-Men' are more widespread than previously thought," said Carly Howett, of the Southwest Research Institute in Texas and lead author of the study.

"The Saturn system - and even the Jupiter system - could turn out to be a veritable arcade of these characters," she said.

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