2 July 2011| NewScientist | 5

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NEVER have old leftovers made so many scientists salivate. After a four year journey, NASA’s Dawn spacecraft is nearing the giant asteroid Vesta, a relic of planet

building that could hold clues to how Earth formed.

“Vesta is a window into the early origins of our solar system,” says Carol Raymond of NASA’s Jet Propulsion Laboratory in Pasadena, California.

At 530 kilometres across, Vesta is one of the biggest denizens of the asteroid belt, the junkyard of leftover planetary building blocks found between Mars and Jupiter.

The pictures snapped by Dawn since mid-May are blurry, showing only tantalising hints of craters. But as the craft slips into orbit around Vesta in mid-July, its topography and chemical composition should be revealed. Scientists think Vesta finished growing long before Earth and the other planets, so might preserve clues to what that era of early planet formation was like.

After a year in orbit, Dawn will head to Ceres, the solar system’s biggest asteroid, to help explain why Ceres, unlike Vesta, seems to contain a lot of water-ice.

Protoplanet probe

TRAPPED gas could prove problematic for the energy industry. Despite the money being poured into efforts to extract natural gas from shale, the economic benefits are unclear.

Studies into shale gas extraction are typically supported by industry bodies. Because their reports are not peer-reviewed, economist Thomas Kinnaman of Bucknell University in Lewisburg, Pennsylvania, decided to review

six of them himself. Three were written by academics at major universities, while three were written by private consultants. All support extracting shale gas, arguing that it creates new jobs and revenue.

Kinnaman found that they all contained flaws that exaggerated the benefits of shale gas extraction to local economies. Most rely on an economic model called IMPLAN, which supposes, say, that local services such as hotel rooms are going unused until the gas industry comes along to spend money on them. In fact, such spending may displace other consumers, creating no net benefit. Kinnaman

also claims that none of the studies measured all the costs and benefits of extracting shale gas, so could not determine if it really offers a net gain (Ecological Economics, DOI: 10.1016/j.ecolecon.2011.02.005).

This week The New York Times published hundreds of gas industry emails, many of which claim that the amount of gas being produced is exaggerated.

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Out for the panda countBy collecting panda droppings, a team of 70 trackers hopes to discover how many of the animals still live in the wild in China, as part of the country’s fourth decadal census of panda numbers. The trackers began their work on Sunday, reports Xinhua, the Chinese news agency, adding that 1596 wild pandas were recorded last time.

Salmonella slayerChickens have been purged of food-poisoning bacteria by inoculating their guts with a rival predatory bacterial species which invades and kills salmonella. Called Bdellovibrio, the bacterium is safe to humans and reduced salmonella by 90 per cent in treated birds, says project leader Liz Sockett of the University of Nottingham, UK (Applied and Environmental Microbiology, in press).

Crow mob rulesA group of crows has learned to recognise an apparently dangerous human, and to harass that person, simply because their neighbours and parents harassed them too. Learning from each other helps the crows respond to unfamiliar threats (Proceedings of the Royal Society B, DOI: 10.1098/rspb.2011.0957).

Los Alamos fireThe US military’s centre for nuclear research, Los Alamos National Laboratory in New Mexico, was threatened by a major wildfire as New Scientist went to press. A spokesman said radioactive materials at the site are stored in partially buried vaults made of hardened concrete and steel, protecting them from fire damage.

Asteroid skims EarthAn asteroid between 8 and 18 metres across buzzed Earth – at a distance of about 12,000 kilometres – on 27 June. Named 2011 MD, it posed no danger but was at least double the size of asteroids previously seen so close.

–Is gas from shale viable?–

Shale or returns

Babies left on hold

“Vesta finished growing long before Earth so might preserve clues to the era of early planet formation”

“Studies into shale gas extraction are typically supported by industry and are not peer-reviewed”

FEAR of getting fired has forced many couples in Europe and the US to abandon plans to have babies.

The uncertain economic climate since the crash in 2008 brought to an end steady increases in birth rates that were seen in almost all European countries since around 2000, according to a report on birth rates in rich countries.

Many factors influence birth rates, “but a main one is economic uncertainty”, says Vegard Skirbekk of the International Institute for Applied Systems Analysis in Laxenburg, Austria, one of the authors of the report (Population and Development Review, DOI: 10.1111/ j.1728-4457. 2011.00411.x).

Recovery may be slow. “Even if you have an economic boom, it could take time before there’s enough confidence, secure enough jobs and high enough salaries for fertility rates to recover,” he says.

60 SEcondS

–Gale crater beckons–

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