IT LOOKS like brushstrokes – it could almost be a Turner – but this is actually nature at its most dramatic. This snapshot from the shows the Tibesti mountains that straddle northern Chad and southern Libya – though a picture like this makes it easy to forget that borders exist.

The mountains, in blue and black at the centre, are a range of volcanoes. The grey and black peak in the bottom right is Emi Koussi, the tallest mountain in Chad at 3415 metres high. There aren’t any recorded instances of any of the Tibesti volcanoes erupting, though ToussidĂ©, the black spot on the far left, does have a reputation for spewing gases and creating hot springs in its crater floor. The white regions are accumulations of carbonate salts, while the orange is desert.

For all their beauty from overhead, plant life is sparse on these mountains, known locally as the “Mountains of Hunger” because they feed so few people. The semi-nomadic Toubou people inhabit the region as salt miners and date and grain farmers, while some cheetahs, gazelles and sheep do roam the region.

Life expectancy in Chad is the lowest in the world at 48 years. An estimated 210,000 people are living with HIV and AIDS – 3.4 per cent of the population – while malaria, typhoid fever and hepatitis A are all major health problems. Thirty-four per cent of under-5s are underweight, and it has the worst maternal mortality rate of any nation. It’s also home to 280,000 refugees from the Darfur conflict across the border in Sudan.

Rebellions frequently flare up in Chad, the most recent resulting in a four-year civil war that ended in 2010. Violent conflicts with Libya and Sudan have also plagued an already crippled country. Only from orbit do the borders not seem to matter.

NO, YOU haven’t slipped into a dream within a dream within a dream. This megacity, which you’d be forgiven for thinking is the dream-limbo city featured in the movie Inception, is . It is home to 8.7 million people. One of the main criteria for the prize is that the city must have a beautiful environment.

Chinese slang for urban sprawl is tan da bing, which means “spreading pancake”. The pancake sure has spread rapidly since the country’s economic reforms of the 1970s and 80s. These reforms have caused the middle class in China to steadily grow, and led to much of the rural population migrating to cities. By 2025, it is estimated that a total of 1 billion Chinese will live in urban areas. As of now, the country has at least 160 cities with over 1 million people. .

Of course this means more housing, more public transportation and consequently more pollution. It’s home to a number of cement and coal factories spewing filth into the atmosphere. (Qing, ironically, translates as “lush” or “green”.)

Only 1 per cent of China’s urban population is breathing air considered clean by European Union standards. because of horrendous air quality, with another 60,000 dying early due to unclean drinking water.

China aims to generate 20 per cent of its energy from renewable sources, so in August this year to help achieve that. The country is now the world’s largest maker of wind turbines and is increasingly focused on solar and nuclear energy. The goal is to clear the skies over the spreading pancake, not to stop the spread itself.

PICTURE the scene. It’s late in the Cretaceous period, 70 million years ago. A group of dinosaurs have gathered at the rim of what will become known as the Grand Canyon. They’re gawping over the edge, just as humans will in millennia to come.

That might not be complete fantasy. It had been thought that the canyon formed 6 million years ago. But now two geologists have evidence it is actually closer to 70 million years old.

Rebecca Flowers at the University of Colorado, Boulder, and Ken Farley at the California Institute of Technology calculated the canyon’s age by examining helium levels in the mineral apatite in the rocks under the western part of the canyon’s floor. Apatite contains uranium and thorium, which decay into helium over time. At high temperatures, like those found deep underground, helium can dissipate. But if surface erosion brings these rocks closer to the surface, as happened at the Grand Canyon, then the cooler temperatures they are exposed to can cause the mineral to hold on to its helium.

Based on higher than expected helium levels, Flowers’s team concluded that the erosion that shaped the canyon began 70 million years ago (Science, ). That will be debated among geologists, but if there is one thing that could add to the wonder of the canyon – up to 29 kilometres wide, 446 kilometres long, 1800 metres deep and very, very old – it is the thought of it filled with dinosaurs.

It’s not just people that have a penchant for cigarettes. Birds living in urban environments often use cigarette butts to line their nests. Unlike in humans, the cigarettes seem to have a beneficial effect – they cut the number of parasites in the nests.

Nicotine-based sprays are already used on some crops to repel insects. To see whether cigarette butts might have a similar effect in urban birds’ nests, from the National Autonomous University of Mexico in Mexico City and colleagues lured parasites to these nests.

The team set up thermal traps in the nests of 27 house finches and 28 house sparrows, species commonly found in cities. The traps had electrical resistors placed on either side of the nest to generate heat, attracting parasites – such as mites – which then got stuck to a strip of adhesive tape attached to the resistor. The team also placed cellulose fibres from smoked or unsmoked cigarettes on top of each resistor to see whether the mites had a preference for either.

Once any chicks had left, the nests were collected for analysis. The team found that the more cigarette fibres the nest contained, the fewer parasites moved in.

Nicotine nest

What’s more, traps containing cellulose from used cigarettes butts attracted 60 per cent fewer mites, on average, than ones with unsmoked cigarettes. This suggests it is indeed the nicotine and other chemicals in a cigarette that repel mites, since these substances are only released once it has been smoked.

Does that mean birds line their nests with cigarette butts to repel parasites? Not necessarily, says Macías Garcia. “One possibility is that the birds are using the cellulose from smoked cigarettes for its thermal properties, as a substitute for other materials such as feathers, down or fur,” he says.

“Much of the work on urban environments has focused on the negative impacts of human activities on birds and other animals,” says Paige Warren of the University of Massachusetts, Amherst, who was not involved in the study. “But there are also many resources that humans provide for animals in the city.”

The team’s next step is to determine whether birds that had a choice between spent butts and unsmoked cigarettes would prefer the former. Birds can distinguish between the two by their smell, and if they prefer to line their nests with spent butts, that would suggest they are aware of the butts’ ability to deter parasites. The team also plan to investigate whether the chemicals in spent cigarettes harm the birds.

Dave Shutler, a biologist at Acadia University in Wolfville, Nova Scotia, Canada, described the study as “very interesting”, but says its results are only vaguely suggestive.

As for the birds’ preferred brand, the nests contained more Marlboro Red butts than any other brand. Montserrat Suárez Rodriguez, who co-authored the study, says she doesn’t know if that’s because the birds prefer Reds or because the students do.

, DOI: 10.1098/rsbl.2012.0931

Editorial: “Space exploration for the history books“

With all the excitement surrounding Curiosity’s first full chemical analysis of Martian soil this week, it’s easy to forget about another, much more distant robotic explorer. Voyager 1 could soon leave our solar system and cross over into interstellar space, the first time any human-made object has left the cosy confines of our planetary neighbourhood.

Yesterday, NASA announced that on its way out, Voyager 1 – which has been travelling through our solar system since 1977 – has encountered a new region of the solar system. It has been dubbed a “magnetic highway”.

The solar wind blows charged particles from the sun’s upper atmosphere around the solar system, creating an enormous “bubble” known as the heliosphere. Charged particles travel along magnetic field lines, and the magnetic highway is thought to be the result of the sun’s magnetic field connecting up with field lines in the clouds of gas and dust of interstellar space.

The highway allows particles with low energy from the heliosphere to jet into interstellar space at high speed and high energy particles from the outside to rush in, an interaction that has been observed around other stars by the Hubble Space Telescope.

Cosmic-ray clue

The magnetic highway was identified when Voyager encountered intense cosmic radiation. The obvious interpretation would be that this happened because Voyager had finally reached interstellar space, yet its instruments did not detect any change in the direction of the magnetic field, which we would expect to see when leaving the heliosphere. This led researchers to conclude that Voyager was in a hitherto unknown region representing a bridge between the solar system and interstellar space.

Cosmic rays routinely enter the heliosphere, but we are shielded from their potentially damaging effects by the Earth’s magnetic field. “The magnetic highway gives us an insight into how the cosmic rays get in,” says Timothy Horbury of Imperial College London.

“Everything we’ve seen [from Voyager] is not what we expected to see,” Horbury says. “People have been working on this for a long time. Just about every expectation we’ve had has been confounded so far.”

Voyager reached the termination shock – the region of the outer solar system where the solar wind starts to slow – in 2003, but it may be several months to a couple of years before the craft fully escapes the solar system. NASA scientists now say .

THESE Algerian oases start looking like footprints on a beach as they stretch out toward the horizon, but the water is underground, not up ahead.

“It’s like the Earth with its living skin pulled away,” says photographer .

Steinmetz found the Adjder oasis, about 100kilometres north-west of the small town of Timimoun, on Google Earth. As he does with most of his photos, he took this while paragliding. “We had a hard time finding the place,” he says. “We couldn’t get a permit to fly in Algeria, so we got there really early. I was flying at sunrise and there were no cops there to give us a hard time.” Five minutes after he snapped the photo, his paraglider’s motor died and he was forced to make an emergency landing.

Buried in the sand are water pumps, powered by electricity brought in by the pylons seen to the left of the photo. The water is used to nourish the palms, under which vegetables are grown. The water table was once an easily accessible 5metres beneath the surface; now it’s about 20metres down, having been depleted by rising demand for water from an increasing population. The sharp edges along the rim of the oases are sand fences built to keep the mobile dunes from burying the gardens.

Deserts have always fascinated Steinmetz. He first visited Algeria when he was 21, after dropping out of Stanford University in California, where he was studying geophysics (he later returned and finished his degree). “I was getting a little bored and frisky,” he says. He has also travelled to deserts in Niger, Kenya, Yemen and Antarctica. These are, he says, “the last great wildernesses”.

A healthy breakfast of half a grapefruit? Not advisable if you are taking certain prescription drugs – the interaction with the fruit could result in an inadvertent overdose.

To find out the extent of the effect, David Bailey of the University of Western Ontario in London, Canada, reviewed the literature and prescribing information of various drugs for any mention of a reaction. He found that of the 85 drugs known to interact with grapefruit, 43 can result in severe adverse effects. The number has increased by 24 per cent since 2008 because new drugs have come onto the market.

Chemicals in the fruit destroy an enzyme in the body that normally breaks down substances such as drugs. That means the drug keeps circulating in the body, which can lead to overdose. A glass of the juice is enough, even if drunk hours before taking a drug, says Bailey.

The most serious adverse effect is a condition known as torsade de pointes, which can cause cardiac arrest and death. It can occur if you mix grapefruit and anticancer drugs.

“Care should definitely be taken with certain drugs,” says Bill Widmer of the US Horticultural Research Laboratory in Fort Piece, Florida, but he adds that there are people who “believe the problem is overstated”.

Journal reference:

You needn’t fry on Mars. Readings from NASA’s Curiosity rover suggest radiation levels on the Red Planet are about the same as those in low Earth orbit, where astronauts hang out for months on the International Space Station. A Mars visit would still be dangerous though, due to the years-long return trip.

Unlike Earth, Mars has no magnetosphere shielding it from solar and galactic radiation. But it does have a thin atmosphere, and readings from two of Curiosity’s instruments suggest this provides some protection.

“This is the first ever measurement of the radiation environment on any planet other than Earth,” Curiosity team member said at a press briefing on 15 November. “Astronauts can live in this environment.”

The rover’s weather station recorded evidence of what is known as a thermal tide on Mars. Sunlight heats the planet’s atmosphere on the side facing the sun, causing it to expand upwards and triggering a decrease in air pressure. But things chill quickly on the other side, so that the atmosphere deflates and becomes denser.

As Mars rotates, the bulge of heated air travels with the “day” side from east to west. Curiosity feels this effect as changes in air pressure over the course of a Martian day, rover scientist Claire Newman of Ashima Research in California said during the briefing.

Radiation shield

At the same time, the rover’s radiation monitor saw daily dips in charged particles that match the increases in air pressure that come with a denser atmosphere. “The atmosphere is acting as a shield to radiation,” Hassler said.

The scientists were not ready to put numbers to the daily radiation dose people would experience on Mars. But the overall levels are lower than those the spacecraft carrying Curiosity recorded during its interplanetary flight, and about what astronauts see on the ISS.

“It’s roughly what we were expecting,” astrobiologist of University College London told żìĂš¶ÌÊÓÆ”.

The biggest threat to Mars voyagers would be the cumulative radiation exposure during the long trip. NASA estimates that a return human mission to Mars would take three years. During that time astronauts might receive more than they get during six months on the ISS.

Setting limits

Building up radiation exposure increases the risk of developing various cancers, so NASA has set limits on how much total radiation astronauts can experience over the course of their careers. Figuring out the exact risk on Mars is crucial to understanding the total dose a human mission would face and whether it is within safe limits, Hassler said.

Solar flares would also be a problem. On Earth these eruptions of charged particles from the sun are largely deflected by the magnetosphere. But Mars enjoys no such protection, and since Curiosity has yet to see a flare, it is unclear how much shielding the thin atmosphere would provide. ‘

Dartnell suggests that a base or colony on Mars could be built underground to avoid surface radiation. Or, with enough advance warning, astronauts could retreat to protective shelters during a flare. But is all that trouble worth it just to send humans where robots already thrive?

“An astronaut or geologist that’s trained in science that has a brain and a pair of hands and pair of eyes with a rock hammer can do a lot more on the surface on Mars before breakfast than a robot can do in weeks,” says Dartnell.

WHY do people say “don’t look down”? Just imagine what you would be missing if the photographer had had similar qualms.

The ants on the ground are working on a Siemens SWT-6.0-154 offshore wind turbine, a giant new machine that is being put through its paces at a wind turbine testing facility in Østerild, Denmark.

The turbine boasts the world’s largest rotor with blades 75 metres long, each as big as the wings of the world’s largest aircraft, the Airbus 380. The machine’s ground-to-tip height is 197 metres, more than twice that of the Big Ben clock tower in London.

The rationale for building bigger turbines is simple: longer blades harvest more energy from the wind. Siemens says the new turbine can generate 6 megawatts, enough to power 5500 households. That is 1000 times more energy per year than the firm’s first generation of wind turbines, which it built 30 years ago with rotor blades just 5 metres long.

British homes may benefit more than most. The UK government is investing £75 billion in offshore power in the hope that it will generate more than a quarter of the nation’s electricity by 2020. Siemens expects the SWT-6.0-154 to play a part. It hopes to install 300 of these turbines in the waters around the UK in the coming years.

It’s not quite “Avengers, assemble!”, but it does the trick. A species of Fijian coral sends out distress signals to gobies to protect itself from encroaching seaweed.

When small staghorn corals () are at risk of being annihilated by turtle weed (), they send out a chemical distress signal. This calls the cavalry – in this case, broad-barred gobies () and redhead gobies () – to come to their aid. The gobies eat the seaweed, protecting the corals.

“I don’t think it’s something that the coral and gobies discovered 50 years ago,” says of the Georgia Institute of Technology in Atlanta. “I suspect it’s been going on for some time.”

To determine what prompted the gobies to eat the seaweed, Hay and colleagues placed them in tanks with only the turtle weed. The gobies were indifferent to the turtle weed until the coral was introduced, at which point they sprang into action.

In return for taking out the seaweed, the coral provide the gobies with shelter. Hay also found that the gobies’ skin secretions became more toxic to predatory fish after eating the seaweed.

Coral saviours

Land plants have similar tricks up their sleeves. Tobacco plants under attack from hungry caterpillars release chemicals that summon predatory insects to eat the caterpillars.

“It really underscores how very little we know about biological interactions on coral reefs, even when processes so integral to the resilience of reefs are considered,” says of the University of Queensland in Brisbane, Australia.

Coral populations have fallen by around 50 per cent in the Great Barrier Reef and 80 per cent in the Caribbean, so they can do with all the help they can get. But of James Cook University in Townsville, Australia, says it is unlikely the gobies will make much difference.

“Certainly, this relationship between one coral species, two fish species and one algal species cannot save the Great Barrier Reef, or any other reef, from decline,” says Figueiredo. Pollution, sediments and climate change pose a far greater threat.

Journal reference: , DOI: 10.1126/science.1225748