Science: fellowship of the rings

The discovery of two thin rings around a modest-sized asteroid has astonished astronomers, whose theories of planetary formation and dynamics had previously suggested that rings would only adorn giant planets such as Saturn.

Chariklo, a coal-black object just 250km in diameter, lies in the outer solar system between Saturn and Uranus. The discovery of its dense and well-defined rings – reported in Nature – was an unexpected outcome of a co-ordinated observation campaign, involving seven telescopes across South America, carried out by astronomers who were puzzled by some features of this asteroid or miniature planet.

“We weren’t looking for a ring and didn’t think small bodies like Chariklo had them at all, so the discovery – and the amazing amount of detail we saw in the system – came as a complete surprise,” says Felipe Braga-Ribas of Brazil’s National Observatory, who led the campaign.

The observations were timed to coincide with a predicted “occultation”, when Chariklo passed in front of a star, making it vanish for a few seconds. To the astronomers’ surprise, there were two short dips in the starlight just before the main occultation and two more afterwards.

“The entire passage only lasted five seconds but we could determine incredible details about the rings,” says Uffe Gråe Jørgensen of the University of Copenhagen. “There are two separate thin rings, which are comprised of ice particles and pebbles. They have been measured at a distance of two billion kilometres with an accuracy of plus or minus a few hundred metres. It is really impressive.”

The discovery explains a puzzle about Chariklo. After its first detection in 1997 it gradually became darker and apparently less icy until 2008, when it began mysteriously to look brighter and icier again. “The identification of Chariklo’s rings now explains these puzzling decreases in brightness,” says Joseph Burns of Cornell University. “They occur as ice-rich rings, which have 15 per cent of Chariklo’s surface area but three times its reflectivity, and become edge-on when viewed from Earth. Like so many baffling observations in science, the answer is obvious once its explanation is known.”

The dynamics of the rings’ formation is unclear, though they are believed to consist of debris left over from a collision long ago. They are probably kept in place by the gravitational effect of small (and unseen) moons orbiting Chariklo.

“The detection of rings around Chariklo will startle many planetary theorists,” says Burns. “But so it has always been in planetary exploration: theoretical ideas rarely generate searches that lead to discovery – rather, discoveries such as this prompt us to new understandings.”

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The gene research pool

GlaxoSmithKline, the largest UK-based drug company, is setting up a scientific collaboration with Britain’s leading genomic research labs, the Wellcome Trust Sanger Institute and the European Bioinformatics Institute.

The partners say that their “pioneering public-private initiative”, the Centre for Target Validation, will use genetic research and data analysis – now advancing at unprecedented speed – to improve success rates in discovering new medicines.

Target validation means proving that a drug candidate’s molecular target in patients actually plays a key role in the disease being treated. So far the pharmaceutical industry’s record has been poor, given that 90 per cent of compounds entering clinical trials fail because they are not safe or effective enough.

Researchers in the UK and US have used X-ray sources to analyse a 50-million-year-old fossil leaf – and show that it was eaten by caterpillars, which left traces of their trumpet-shaped feeding tubes.

“Research has just reached the stage where associations of genetic variations with disease are firm enough to provide a secure base for drug discovery,” says Patrick Vallance, president of pharmaceuticals R&D at GSK. “Now we can base our decisions on a real knowledge of human biology.”

The new centre, housed on the Wellcome Trust Genome Campus outside Cambridge, will be a substantial operation, with 50 researchers and more than £10m initial funding from GSK.

Perhaps the most remarkable aspect of the collaboration is its openness – its data will be published without restriction. Though GSK will gain some competitive advantage by having its scientists on the spot, guiding the programme, it does not have the first right to exploit discoveries that is normally a feature of academic-industry partnerships.

“It is enlightened self-interest by GSK,” says Ewan Birney of the European Bioinformatics Institute, interim head of the new centre. “This is a pre-competitive problem best solved in the public domain.”

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Diagnosis at a distance

Much of the high-tech equipment being developed to monitor patients’ health depends on instruments implanted in them or stuck on to their skin. But progress is also being made with technology that tracks patients from a distance, with cameras attached to a powerful image-processing system.

A good example is being developed by Xerox, the US imaging company. Its scientists believe that contact-free video monitoring, combined with data analytics, can be more acceptable to patients because it avoids wires, discomfort and risk of infection. Working with Manipal University Hospital in India, the Xerox researchers use algorithms to convert data collected by the cameras into vital signs. The system picks up subtle changes that may be invisible to the human eye, such as a slight reddening of the skin as the heart pumps more oxygenated blood.

“Our initial work at Manipal was in the neonatal unit, evaluating the algorithms to monitor infant vital signs with cameras, but that has quickly expanded into other areas,” says Lalit Mestha, project leader.

The team is also working with the University of Rochester Medical Center in New York on a project that uses cameras to detect atrial fibrillation, an irregular heartbeat that can increase the risk of stroke by a factor of five.

In the longer term, cameras open up the possibility of diagnosing patients in their homes and in places far from medical specialists.

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Microbes blamed for prehistoric extinction

Researchers at the Massachusetts Institute of Technology have identified a new culprit for the world’s greatest mass extinction, which wiped out more than 90 per cent of species on land and sea some 252 million years ago. They say that the primary cause of “the Great Dying” was neither an asteroid impact nor changes in the atmosphere caused by supervolcanic activity, as others have suggested, but the explosive growth of methane-generating microbes.

The MIT team published evidence in Proceedings of the National Academy of Sciences that microbes called Methanosarcina bloomed suddenly in the oceans, spewing out gigantic amounts of methane. This radically changed the chemistry of the atmosphere and oceans, as the methane reacted with oxygen to form carbon dioxide. The consequences were extreme climate change and acidification of seawater, which most species could not survive.

The scientists’ argument has several parts: the geological record shows an exponential build-up of CO2, which fits microbial growth rather than volcanism; and genomic analysis of Methanosarcina descendants alive today shows that the microbes acquired the ability to generate methane rapidly through a genetic change about 250 million years ago.

But volcanic activity did make one essential contribution to the Great Dying, according to the MIT analysis. It provided nickel – an essential mineral nutrient for Methanosarcina, without which the bacteria would have stopped their explosive growth more quickly.