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Lightning strikes fling high-energy electrons into space
Research news and discovery
NICK MOIR/OCULI/VU
In brief– Antimatter factory
Even in space, you won’t be safe from lightning strikes SATELLITES and astronauts orbiting the Earth have little to fear from the wind and rain of a storm far below – but the lightning might be a different matter. Bolts of lightning are already known to produce X-rays and gamma rays. Now Joseph Dwyer of the Florida Institute of Technology and colleagues have discovered that lightning in the lower atmosphere also flings a shower of high-energy electrons towards space (Geophysical Research Letters, DOI: 10.1029/2007GL032430). According to the team’s satellite measurements, each electron is 100 times more
energetic than the photons of X-rays used for medical imaging. This means they would easily penetrate the radiation shielding fitted to satellites or the space shuttle. Dwyer thinks these electrons are produced when gamma rays from the lightning hit gas molecules in the atmosphere. If this happens at altitudes of 40 kilometres or more, the electrons could slip through the thin air and escape into space, he says. Once there, our planet’s magnetic field whips them around the globe. A few lightning flashes are unlikely to produce enough electrons to disrupt satellite or spacecraft electronics, but the particles might pose a threat if the Earth’s magnetic field turns out to trap them for months, allowing them to accumulate, says Dwyer.
Biofuel needs fertiliser to pay its way THE future of biofuels just got brighter. Yields from farm-scale plantings of the switchgrass Panicum virgatum suggest that producing ethanol from the cellulose in these crops will be about twice as energy-efficient as previously estimated. Researchers led by Ken Vogel of the US Agricultural Research Service in Lincoln, Nebraska, paid farmers in Nebraska, North 14 | NewScientist | 12 January 2008
Dakota and South Dakota to grow switchgrass for five years in plots ranging from 3 to 9 hectares. They measured the energy needed to grow the crops, including that used to make fertilisers and the diesel consumed by farmers’ vehicles. From the biomass of grasses harvested, they calculated that ethanol derived from them should yield 5.4 times as much
energy as all these inputs combined (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0704767105). Vogel’s results will not please ecologists who want to restore prairie ecosystems by growing mixtures of grasses without fertilisers, and use the cellulose they produce to make ethanol. “It just takes too much land,” argues Vogel, who calculated that fertilised switchgrass monocultures will give higher yields per hectare.
WHERE does the antimatter in our galaxy come from? We know there is antimatter within the Milky Way because of the telltale gamma radiation produced when electrons collide with their antiparticles. But where these particles, called positrons, come from is less well understood. Now astronomer Gerry Skinner of the University of Maryland, College Park, and colleagues say that neutron stars and black holes might be leaking positrons into space (Nature, vol 451, p 159). They infer this from their observations of the telltale gamma-ray emissions, which turn out to be stronger on one side of the galaxy. This region also holds more of a certain kind of binary star, in which a neutron star or a black hole is consuming gas from an ordinary stellar companion. The team made their measurements using Integral, the European Space Agency’s orbiting gamma-ray observatory.
Garlic helps fight arsenic poisoning GARLIC may provide some relief for millions of Bangladeshis and Indians whose drinking water is contaminated with arsenic. Keya Chaudhuri of the Indian Institute of Chemical Biology in Kolkata, and her colleagues gave rats daily doses of arsenic in their water, in levels equivalent to those found in groundwater in Bangladesh and West Bengal. Rats which were also fed garlic extracts had 40 per cent less arsenic in their blood and liver, and passed 45 per cent more arsenic in their urine (Food and Chemical Toxicology, DOI: 10.1016/j.fct.2007.09.108). Chaudhuri says that sulphurcontaining substances in garlic scavenge arsenic from tissues and blood. She advises people in at-risk areas to eat one to three cloves of garlic per day as a preventative. www.newscientist.com
NICK MOIR/OCULI/VU
In brief– Antimatter factory
Even in space, you won’t be safe from lightning strikes SATELLITES and astronauts orbiting the Earth have little to fear from the wind and rain of a storm far below – but the lightning might be a different matter. Bolts of lightning are already known to produce X-rays and gamma rays. Now Joseph Dwyer of the Florida Institute of Technology and colleagues have discovered that lightning in the lower atmosphere also flings a shower of high-energy electrons towards space (Geophysical Research Letters, DOI: 10.1029/2007GL032430). According to the team’s satellite measurements, each electron is 100 times more
energetic than the photons of X-rays used for medical imaging. This means they would easily penetrate the radiation shielding fitted to satellites or the space shuttle. Dwyer thinks these electrons are produced when gamma rays from the lightning hit gas molecules in the atmosphere. If this happens at altitudes of 40 kilometres or more, the electrons could slip through the thin air and escape into space, he says. Once there, our planet’s magnetic field whips them around the globe. A few lightning flashes are unlikely to produce enough electrons to disrupt satellite or spacecraft electronics, but the particles might pose a threat if the Earth’s magnetic field turns out to trap them for months, allowing them to accumulate, says Dwyer.
Biofuel needs fertiliser to pay its way THE future of biofuels just got brighter. Yields from farm-scale plantings of the switchgrass Panicum virgatum suggest that producing ethanol from the cellulose in these crops will be about twice as energy-efficient as previously estimated. Researchers led by Ken Vogel of the US Agricultural Research Service in Lincoln, Nebraska, paid farmers in Nebraska, North 14 | NewScientist | 12 January 2008
Dakota and South Dakota to grow switchgrass for five years in plots ranging from 3 to 9 hectares. They measured the energy needed to grow the crops, including that used to make fertilisers and the diesel consumed by farmers’ vehicles. From the biomass of grasses harvested, they calculated that ethanol derived from them should yield 5.4 times as much
energy as all these inputs combined (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0704767105). Vogel’s results will not please ecologists who want to restore prairie ecosystems by growing mixtures of grasses without fertilisers, and use the cellulose they produce to make ethanol. “It just takes too much land,” argues Vogel, who calculated that fertilised switchgrass monocultures will give higher yields per hectare.
WHERE does the antimatter in our galaxy come from? We know there is antimatter within the Milky Way because of the telltale gamma radiation produced when electrons collide with their antiparticles. But where these particles, called positrons, come from is less well understood. Now astronomer Gerry Skinner of the University of Maryland, College Park, and colleagues say that neutron stars and black holes might be leaking positrons into space (Nature, vol 451, p 159). They infer this from their observations of the telltale gamma-ray emissions, which turn out to be stronger on one side of the galaxy. This region also holds more of a certain kind of binary star, in which a neutron star or a black hole is consuming gas from an ordinary stellar companion. The team made their measurements using Integral, the European Space Agency’s orbiting gamma-ray observatory.
Garlic helps fight arsenic poisoning GARLIC may provide some relief for millions of Bangladeshis and Indians whose drinking water is contaminated with arsenic. Keya Chaudhuri of the Indian Institute of Chemical Biology in Kolkata, and her colleagues gave rats daily doses of arsenic in their water, in levels equivalent to those found in groundwater in Bangladesh and West Bengal. Rats which were also fed garlic extracts had 40 per cent less arsenic in their blood and liver, and passed 45 per cent more arsenic in their urine (Food and Chemical Toxicology, DOI: 10.1016/j.fct.2007.09.108). Chaudhuri says that sulphurcontaining substances in garlic scavenge arsenic from tissues and blood. She advises people in at-risk areas to eat one to three cloves of garlic per day as a preventative. www.newscientist.com