4 December 2010 | NewScientist | 7

survive where other species might not, such as mice and ryegrass, also happen to be the best reservoirs for infection, Keesing’s team found. She believes this is because weed species tend to live fast and die young, putting their energy into rapid growth and reproduction instead of immunity.

There are too many examples of both plants and animals for this to be just coincidence, she says.

Diseases of wildlife can jump to people. Keesing says we need to find landscapes that maintain enough biodiversity to keep a lid on them.

Meteorite lightningSPACE debris falling into the atmosphere may cause mysterious ball lightning.

Thousands of people have seen floating orbs of light, sometimes during thunderstorms, but their origin has never been established. The weather was clear when Don Vernon, a farmer in Queensland, Australia, spotted two green balls descending from the sky on 16 May 2006. Oddly, the second rolled down a hill, bounced and then vanished.

Stephen Hughes, an astrophysicist at the Queensland University of Technology in Brisbane, says the first was probably a bright meteor caused by debris from Comet 73P, which came closer to Earth at that time than any other comet in 20 years. The second, he says, was ball lightning triggered by the meteor.

The cometary debris ionised the atmospheric gas it passed through, boosting the current that normally flows between the ionosphere – an electrically charged region in the upper atmosphere – and the ground, Hughes believes. When this “supercharged” conduit hit the soil, it formed a plasma ball, he argues (Proceedings of the Royal Society A, DOI: 10.1098/rspa.2010. 0409). Impacting space junk might also produce the effect, he says.

Political rocketryPOLITICAL clout may play a role in the design of NASA’s next heavy-lift launcher.

Congressmen from Utah are pressuring NASA to promise that the rocket will use solid-fuel motors like those produced by the Utah firm ATK. They recently met with NASA chief Charles Bolden to “explain [our] interest in ensuring that Utah’s solid rocket motor industry is protected”, Senator Orrin Hatch said.

The delegation claims that the NASA authorisation bill that President Barack Obama signed

into law in October legally requires the use of the motors, but in fact the law leaves a significant loophole. It says NASA should use existing technology from the shuttle and the now-defunct Ares

launchers – both of which use solid rocket boosters – “to the extent practicable”.

The US’s previous heavy-lift launcher, the powerful Saturn V, did not use solid rockets.

“Utah Congressmen want NASA to promise that its next rocket will use solid-fuel motors”

CHOLERA in Haiti is spreading faster than expected, with the World Health Organization now predicting 400,000 cases before this outbreak subsides, half of these in the next three months. The count stood at less than 100,000 as New Scientist went to press.

Only 2.3 per cent of the sick are dying, partly because of prompt rehydration therapy. But, ominously, reports suggest doctors are already struggling to cope with the existing number of cases. United Nations’ officials and aid groups have issued pleas for more international aid.

The epidemic could be slowed if many Haitians could be given one of the three oral cholera vaccines available – but there are no plans for this as there are “too few

doses on hand”, says Peter Hotez at George Washington University in Washington DC. People in regions in which cholera is prevalent do not use much vaccine as vaccine immunity is brief. Vaccines are mostly used by travellers, so only small amounts are made. Hotez and others are calling for a global stockpile for emergencies.

Some scientists have suggested that Haiti’s cholera originated with natural populations of marine bacteria. Matt Waldor, a cholera specialist at Harvard Medical School in Boston, calls this “wrong”, and says “the genetic and epidemiologic evidence that human activities account for the introduction… is overwhelming”. See page 26 for more on the outbreak’s origins.

Haiti’s cholera set to soar

–Prompt therapy saves lives–

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Rise of the dinos The collapse of tropical rainforests 300 million years ago paved the way for the rise of the dinosaurs. As the forests died back, early reptiles evolved a host of new lifestyles to cope, including eating plants and hunting each other (Geology, vol 38, p 1079).

Toxic snow on EverestFollowing in Edmund Hillary’s footsteps? Don’t drink the water on your way up. Dangerous levels of arsenic and cadmium have been found in snow samples from Mount Everest, 7000 metres above sea level. Pollution from Asian industry is probably to blame (Soil Survey Horizons, vol 51, p 72).

Extreme HIV evolutionJust a century after making the leap from chimpanzees to humans, HIV-1 has evolved into an astonishing 48 new strains, according to a history of the virus. Substantially different forms of HIV could evolve in the future, making it more difficult to combat (The Lancet Infectious Diseases, DOI: 10.1016/S1473-3099(10)70186-9).

Red dwarf bountyThe universe contains three times as many stars as we thought. For the first time, astronomers at Yale University have identified the faint signature of red dwarfs outside the Milky Way. In eight nearby elliptical galaxies, the researchers found that the low-mass, dim stars were more bountiful than expected (Nature, DOI: 10.1038/nature09578).

Car bomb kills physicistMajid Shahriari, a nuclear physicist at Shahid Beheshti University in Tehran, Iran, has been killed in a bomb attack in the capital. In January, Masoud Ali Mohammadi, a particle physicist at the University of Tehran, was also killed in a car bomb attack. Iran says the killings are linked to its nuclear programme.

For daily news stories, visit www.NewScientist.com/news

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