Your body may use it to catch a tan, but now the skin pigment melanin has been repurposed for the first time to make batteries. These may one day offer a safer way to power electronic devices that can be swallowed or inserted into the human body for drug delivery or internal monitoring.

Rechargeable lithium-ion batteries are widely used in electronics because they are very efficient and can hold their charge for long periods. But because they contain lithium, these batteries are potentially toxic if used long-term inside the body. So at Carnegie Mellon University in Pittsburgh, Pennsylvania, wanted to find a way to build batteries from biological materials.

“If we could safely ingest devices, then we could overcome a lot of the issues we have with current implanted devices, such as infection and inflammation,” says Bettinger. “So we started with substances that are biologically derived and occur in the human body naturally, like sodium, water and melanin.”

Skin power

To make the bio-battery, Bettinger and his team engineered positively charged anodes out of a mixture containing high levels of melanin, the substance that creates pigment in humans and many other animals. They then introduced sodium ions and loaded the anodes into a steel mesh structure. Melanin’s uniform chemical structure means it can pack in plenty of ions, which is key to determining how much charge a battery can hold. This battery could discharge for up to 5 hours, although at a lower power output than standard batteries.

Other biomaterials such as plant matter have been tested as potential electrodes, but they require extra chemical modifications to hold a charge. By contrast, melanin can be used in its natural form, and it is very possible that it could be simply harvested from human skin, says Bettinger. However, using a source with a much higher density of the pigment – the ink sac of a squid, for example – would be more efficient.

“This paper describes a really clever route to producing batteries out of biodegradable materials,” says at the University of Illinois at Urbana-Champaign. Although the current version isn’t fully biodegradable, it shows how batteries could one day be made to dissolve harmlessly in the body.

“The idea is that such technologies could be used as power sources for systems that go into the body, monitor a wound-healing process, deliver therapy as necessary and then naturally disappear after the wound is completely healed. Similar sorts of systems might be designed to treat cancerous tumours, or to treat bone fractures or torn ligaments.”

The researchers also found that natural melanin is better at holding charge than synthetic versions. But the melanin battery is not as efficient as the lithium-ion variety, partly because natural melanin is usually found in very dense granules, says Bettinger. Finding a way to make it spongy would help it soak up more sodium ions and pack in even more charge.

Journal reference: ,

Astrophile is our weekly column on curious cosmic objects, from the solar system to the far reaches of the multiverse

Object: Europa’s subsurface ocean
Interesting property: Intense turbulence

As moons go, Europa is doing pretty well in the looks department. While other wrinkled and pockmarked planetary bodies look their age, Jupiter’s moon, despite being billions of years old, is one of the smoothest objects in our solar system.

However, this moon is far from flawless. Europa is suspected to have a perpetually dark, liquid water ocean enclosed beneath a thick shell of water ice – around 40 per cent of which is covered with long, dark scratches and scars.

The prospect of liquid water places Europa near the top of the list of places in our solar system that might host alien life. However, it is hard to know what’s actually going on in the sub-surface ocean. Does it teem with alien microbes – perhaps even bigger creatures – or is it a vast, inky, sterile wasteland?

The only window we have on the ocean is its icy surface, so scientists try to read its criss-cross scars for clues. But whether this so-called chaos terrain can tell us about what’s going on underneath such a thick layer of ice is hotly disputed.

Oceanic chaos

The criss-cross pattern is likely to be caused by warmer and thinner regions of ice breaking and refreezing. It is much more abundant around the moon’s equatorial regions than at its poles – but why should this be the case?

Unlike on Earth, the temperature difference between the equator and poles cannot be explained by the effects of the sun because its light is too faint and Europa’s surface too reflective.

Another theory involves Jupiter’s gravitational pull, which would produce tectonic forces and heat up Europa’s ocean – but models have shown that this would heat the poles more than the equator.

The latest study suggests that turbulence in Europa’s ocean sculpts the chaos terrain on the icy surface. It was previously assumed that an effect caused by the moon’s rotation – known as the Coriolis force – dominates the ocean’s flow, funnelling heat to high latitudes. The new model instead relies on ocean currents caused by convection of the moon’s internal heat.

Mix for life

The team found that this produces a chaos terrain very similar to the one seen on Europa. “The resulting flow is less organised, but more vigorous in the equatorial region,” says researcher of the Max Planck Institute for Solar System Research in Lindau, Germany. “This correlates nicely with the distribution of chaos terrain.”

The model suggests that the ocean is extremely turbulent, with three strong ocean jets. So despite the thickness of Europa’s icy shell, it seems that properties of its ocean are writ in the ice. “We may be able to understand Europa’s ocean just by looking at the surface,” says Wicht’s colleague of the Georgia Institute of Technology in Atlanta.

A turbulent ocean would be beneficial for any life there because it would help shift nutrients from the sea floor into the rest of the ocean, says Schmidt’s other colleague, of the University of Texas at Austin. Microbes can live in stagnant water, but knowing the ocean is turbulent makes life much more likely.

Upcoming missions such as the European Space Agency’s , will map Europa’s chaos terrain via fly-bys in 2030, and potentially , will find out more – although it is just a concept at the moment.

Studies of Europa’s chaos terrain may have relevance beyond Jupiter’s moon. “Icy subsurface oceans may be commonplace in the outer solar system,” says of the University of Oxford, a member of the ESA Science Working Team for JUICE. “JUICE will also search for any active plumes and vents, just like on Saturn’s moon Enceladus, to offer a glimpse into this icy ocean. This will be a great test of this sort of model for the icy worlds of our solar system.”

Journal reference: Nature Geoscience Letters,

MOMENTS after the big bang, the primordial soup of subatomic particles congealed into a few light elements, such as hydrogen, helium and lithium. But there’s a problem: models of the big bang indicate that there should be much more lithium than we see today. Are our theories wrong?

The latest search has turned up more lithium than ever before, but not enough to fit the models. That strongly hints that some unknown physics may have come into play right after the big bang.

Earlier research probed the atmospheres of stars near the edge of the Milky Way for lithium-7, the most common isotope. These stars are very old, and the amount of lithium they contain is related in a predictable way to the composition of the early universe. The observations focused on the stars’ outer layers because they don’t mix with material from the core, where lithium can be produced.

The amount of lithium-7 these studies found is about a third of what big bang models say it should be. One possible reason is that lithium is sinking into the stars’ interior and being destroyed by high temperatures.

Christopher Howk of the University of Notre Dame in Indiana and colleagues have expanded the search to gas clouds in a nearby satellite galaxy, the Small Magellanic Cloud. Using the Very Large Telescope (VLT) in northern Chile, they discovered nearly as much lithium in these clouds as big bang models predict (Nature, ).

The shortfall remains significant, though. That’s because lithium is also produced by natural particle collisions and in supernovae. The new finding only deepens the mystery, says Howk. “Only if there is no change in the lithium abundance since the big bang is this problem solved,” he says.

“Only if there is no change in the lithium abundance since the big bang is this problem solved”

Other recent work also complicates things by hinting that the accretion disks of black holes can produce large amounts of lithium-7. Until recently, this idea had always been applied to the supermassive black holes found in the cores of galaxies. Now of the Technical University of Munich, Germany, and Fabio Iocco of Stockholm University in Sweden have shown that even stellar-mass black holes can generate lithium as they swallow material from an orbiting companion star (). Such systems, called microquasars, are very common, so their small yields of lithium can contribute significantly to the element’s abundance, says Pato.

All this suggests that the amount of lithium we see represents an even bigger shortfall from what should have been created after the big bang. Howk wonders whether exotic physics just after the big bang could be to blame. One speculation is that reactions involving dark matter – the enigmatic stuff thought to account for much of the universe’s mass – could have suppressed lithium production.

Howk and colleagues plan to test this idea at the VLT in November with more observations of the Small Magellanic Cloud.

Iran isn’t a country with a high profile in space tourism – but that could soon change. On Wednesday, the (ISA) announced its intention to launch a live Rhesus monkey into space. But can it bring the animal back?

A previous attempt to launch a craft carrying a monkey failed last October, stalling Iran’s space ambitions. Now the mission is back on track, with a launch planned for mid-August, after the Islamic month of Ramadan ends.

It is not the first time Iran has shown interest in launching animals into orbit. In 2010, the ISA’s carried worms, a mouse and two turtles as passengers. More significantly, .

It would be a major advance in Iran’s space programme if the country is able to successfully return a monkey to Earth. “This would show its capability to return scientific payloads from orbit,” says of King’s College London, who studies the military use of space. “However, to launch a human may take some time.”

Iranian forays into space exploration have surprised international onlookers due to their speed and secrecy. Iran has launched three domestically made satellites in as many years, and a fourth is to be launched in the next few months. Iran is the ninth country to put domestically built satellites into orbit, and the sixth to send animals into space.

Military milestone?

Some countries are wary of an Iranian space presence, concerned that the technology used to carry satellites, animals and potentially humans into space could also be used to transport weaponry. A successful round-trip for the monkey could have “worrying implications”, says Jasani. “This launch would be a major milestone in a military sense. Iran, like many other spacefaring nations, is developing a space programme not only for the sake of prestige but also for national security reasons.”

Iran has repeatedly denied that there are any military intentions behind their space programme, instead stating reasons including earthquake monitoring, imaging and improvement of telecommunications. Their space programme remains ambitious, with the aim of launching a human into space by 2020, and landing an astronaut on the moon by 2025.

of the Secure World Foundation, which promotes ideas about the use of outer space, says it is interesting to compare Iran’s space programme with that of North Korea. “The world community hasn’t tried to stop Iran’s rocket program like they have North Korea’s because overall Iran is doing things that demonstrate it is serious about having a space programme. Although North Korea says they have a space programme, their actions lead many to conclude that it’s really just a way to legitimise their development of ballistic missile technology.”

Weeden says Iran’s motivation is more likely to be to improve its national image rather than develop military capability in space.

“I think prestige is the most likely because it’s the main reason why most countries pursue human spaceflight. You can demonstrate your country’s technical and scientific prowess with robotic satellites, but those are hard to show off because they stay in space. A living, breathing organism is much easier for the public to identify with and, if you can bring it back down safely, much easier to publicise.”

It seems an excess of “left-handed” molecules, long assumed to be a signature of life, can be created inside asteroids through a non-biological process. That puts a damper on missions that intended to look for this chemical signature as evidence of biological activity on other worlds.

Molecules have handedness, or chirality, if their mirror-images cannot be superimposed upon each other, rather like your right and left hands. Life on Earth is built almost exclusively on left-handed amino acids, so scientists have assumed that a strong left-handed bias is a fundamental part of biochemistry.

Instruments on the European Space Agency’s ExoMars and Rosetta missions are designed to search for an excess of left-handed molecules as an indicator of life.

But a new study found that meteorites collected from Canada’s Tagish Lake also have a excesses of left-handed aspartic and glutamic acids, two amino acids that are common in terrestrial life.

Natural path

The researchers propose that, in the solar system’s early days, heating as a result of radioactivity could have melted ice trapped deep inside asteroids. Liquid water then dissolved already present amino acids, which crystallised into mostly left-handed groupings.

Previous studies had seen small chiral excesses in amino acids from meteorites. But the new study is the first to propose a natural path for large left-handed enrichments in nonbiological materials, says team leader of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

“As evidence mounts that [left-handed] excess occurs naturally across bodies in the solar system, any strategies designed to search for life based on looking for this excess require serious rethinking,” says of the SETI Institute in Mountain View, California.

Even without chirality, though, the search for extra-terrestrial life can continue. “A swimming pool full of [left-handed] amino acids is not alive,” says Harald Steininger, a project scientist for the on ExoMars. “Life shows in many different aspects, and chirality is only one of them.”

Journal reference: Meteoritics & Planetary Science, DOI: 10.1111/j.1945-5100.2012.01400.x

Video: How a star couple evolves

For massive stars, connecting with a partner is about more than just romance: it’s a matter of life and death. Now it seems that pairing up is the norm among the universe’s heftiest, most influential stars.

That in turn suggests that inter-star relationships have a bigger role to play in galactic evolution and dynamics than previously thought – with important implications for explaining stellar behaviour, evolution and history.

Though rare compared with stars like our sun, the heft of massive stars, many times bigger than our sun, means they have a disproportionate effect on the chemical make-up of galaxies.

Very massive stars end their lives in huge explosions, seeding the universe with heavier elements, such as iron and oxygen, forged in their nuclear cores. “Massive stars alone evolve to liberate elements that have undergone advanced stages of nuclear fusion,” says of University College London. “They are of central importance in determining the chemistry of the universe.”

Unimportant singleton

Until now, most models used to study galactic evolution have assumed that these influential behemoths are single. Star pairs orbiting close together in a system known as a binary, meanwhile, were thought to be unusual, and the contribution of their interactions has been difficult to determine reliably, says Howarth.

To establish whether these assumptions are accurate, of the University of Amsterdam and colleagues looked at 71 residing in six loosely bound, or “open”, star clusters within the Milky Way. Searing hot O-type stars have masses greater than 15 times that of our sun.

The team found that more than 70 per cent of these behemoths dance closely around nearby companions to form binaries – a number far higher than expected.

This suggests that an “astonishing” number of massive stars pair up and go through significant physical changes – not accounted for in previous models – before they die, says Sana. Single stars, meanwhile, are a “relatively unimportant part of the population”, says Sana’s colleague Chris Evans of in the UK.

Vampire stars

This new understanding may already be leading to a more accurate interpretation of stellar behaviour and evolution.

In 40 to 50 per cent of the O-type stars in the team’s sample, the companion is a “vampire star” that siphons material off its partner. By sucking up the larger star’s outer layer of hydrogen, the vampire rejuvenates itself and can live longer than other stars of similar mass. The stripped star, meanwhile, often ends up exploding as an unusually hydrogen-poor supernova.

Previously, astronomers had noticed that around a third of stars that explode as supernovae are observed to have surprisingly little hydrogen but could not explain why. The newly-observed dominance of massive star binaries could explain the lack of hydrogen, especially as the researchers report that the proportion of hydrogen-poor supernovae closely matches the proportion of vampire stars found by this study.

A vampire-victim dynamic is not the fate of all massive binaries, however. The researchers calculate that one-third of O-type stars are in partnerships where the mass exchange prompts the two stars to spiral towards each other and violently merge to form a much larger star.

Journal reference: , DOI: 10.1126/science.1223344

WE ARE not alone – in one sense at least. A trio of planets orbiting a sun-like star has the most similar layout to our solar system yet seen.

The discovery supports the idea that planets emerge from relatively flat discs of material encircling stars and, at first, orbit neatly in the same plane, just as our eight planets circle the sun. This long-held notion has recently been called into question by a haul of planetary systems with wildly skewed orbits.

Most of these chaotic systems contain hot Jupiters, massive gas giants that circle their stars in a tight embrace. These behemoths frequently have dramatically tilted and sometimes even backward orbits. The big question is whether hot Jupiters form from slanted discs of material or if the planets scatter into odd positions when a tidy system is somehow disrupted by gravitational interactions among its multiple worlds.

Using data from NASA’s Kepler space telescope, a team led by Roberto Sanchis Ojeda of the Massachusetts Institute of Technology examined a star system called Kepler 30 and measured how well the planets’ orbits line up with the star’s rotational plane, something known as obliquity.

They found that the orbits of all three planets nearly align with the star’s equator (Nature, ). The planets are about four, nine and 12 times the size of Earth and circle far enough from their star that none is considered a hot Jupiter.

Finding more aligned systems free of hot Jupiters would suggest that games of planetary pinball are the primary cause of planets in skewed orbits, say the authors. That would back the idea “that wild, scattered systems are in the minority”, says of the University of Florida, Gainsville, who wasn’t on the team.

From launch to splashdown, all in under half an hour: not bad for an inflatable spacecraft.

This morning NASA’s IRVE-3 – the third and heaviest of a series of – successfully launched from NASA’s Wallops Flight Facility in Virginia at 7:01 am local time. It landed in the Atlantic Ocean, off the coast of North Carolina, just 20 minutes later.

Like IRVE and IRVE-2 before it, IRVE-3 has an inflatable outer shell, which slows and protects the craft as it enters an atmosphere at hypersonic speeds.

In order to test the possibility of carrying heavier payloads through planetary atmospheres, IRVE-3 carried more than twice the payload of its predecessors and was installed with a heat shield, testing its ability to withstand atmospheric re-entry. The team also tweaked the craft’s centre of gravity to see if this would lead to more precise manoeuvres than in previous tests.

‘Perfect launch’

The vehicle travelled some 450 kilometres over the Atlantic Ocean, outside Earth’s atmosphere. The 308-kilogram inflatable heat shield – or aeroshell – separated from the nose cone of its launch vehicle and was then inflated with nitrogen into a mushroom shape before falling through Earth’s atmosphere.

“The launch went perfectly,” says of NASA’s IRVE-3 team.

Planned initially to enable the exploration of higher-altitude terrain on Mars, the IRVE-3 team is also anticipating its use as a link between here and the International Space Station, transferring waste and other cargo.

While the launch of IRVE-3 was not intended to show off a finished product, “it demonstrates that the technology is valid, and can be scaled up for future mission applications”, says Hughes.

There’s a new bond in town, and this secret agent works best in extreme situations.

The bond, of the chemical variety, occurs in the presence of very strong magnetic fields, such as those found around ultra-dense white dwarf stars. Its discovery not only demonstrates the existence of an unfamiliar and exotic type of chemistry, it may also give insight into the behaviours of these mysterious stellar bodies.

White dwarfs are the remnant cores of low-mass stars that have exhausted all their fuel. They are thought to be the final state for most of the stars in our galaxy. Though they have masses comparable to that of our sun, white dwarfs only occupy the same amount of space as a small planet like Earth, making them incredibly dense.

They also exhibit super-strong magnetic fields on the order of 100,000 tesla – 10 billion times greater than Earth’s magnetic field, and 10 million times greater than that of an average refrigerator magnet. This intense field can affect the behaviour of the electrons that make up chemical bonds.

Exclusion principle

On Earth, atoms usually bond either covalently, by sharing electrons with neighbouring atoms, or ionically, via electrostatic attractions created by the transferral of electrons.

The electrons that give rise to these bonds are governed by the Pauli exclusion principle: two cannot occupy the same quantum state simultaneously. To avoid this scenario, electrons in bonds normally pair up in couples of opposing spin. But under the intense magnetic field of a white dwarf, “this spin interacts with the external field, acting like a little magnet,” says lead author at the University of Oslo in Norway.

As a result, the spins of both electrons align with the external field, forcing one of the electrons to move into a different position known as an anti-bonding orbital. Normally, this would spell the end of any chemical bonds. “In a normal molecule these anti-bonding orbitals are not occupied by electrons,” says Lange. “If they are occupied, the atoms are no longer bound together and the molecule breaks apart.”

Unfamiliar chemistry

Lange and his colleagues wondered if things might be different around white dwarfs. “Chemistry and molecular physics become very different in the presence of a strong magnetic field,” says , Lange’s colleague. “Even very simple systems behave in exotic and unfamiliar ways compared to what we are used to under normal conditions.”

With this in mind, the researchers used quantum chemical simulations to model chemical bonding in hydrogen and helium atoms in the magnetic field of a white dwarf. In both cases, the atoms were drawn into strongly bonded pairs.

Because the electrons in these bonded atoms occupied anti-bonding orbitals – which is forbidden in both types of known chemical bond – the researchers say this is a new type of bond. They have dubbed it “perpendicular paramagnetic bonding”.

The work shows that “molecules that don’t exist under normal conditions can exist in a sufficiently large magnetic field,” says Lange.

of the University of Oxford, who was not involved in the study, called the research “excellent”, adding that “the results show that a magnetic field can stabilise molecules”.

Reading the stars

Although the authors say that replicating the new bonds on Earth isn’t feasible, the finding highlights how molecular chemistry may change in the presence of extreme conditions.

“I think there are probably other weird or unfamiliar types of bonding to be discovered,” says Tellgren.

Such work will also help to further our knowledge of astrophysical objects like white dwarfs. By understanding how matter behaves around these objects, it may be possible to interpret their observed spectra more easily and accurately, and to better unravel what is happening in their atmospheres.

Journal reference: , DOI: 10.1126/science.1219703

Whether a tree branch or a computer mouse is the target, reaching for objects is fundamental primate behaviour. Neurons in the brain prepare for such movements, and this neural activity can now be deciphered, allowing researchers to predict what movements will occur. This discovery could help us develop prosthetic limbs that can be controlled by thought alone.

To find out what goes on in the brain when we reach for things, biomedical engineers and Thomas Pearce at Washington University in St Louis, Missouri, trained two rhesus macaques to participate in a series of exercises. When the monkeys reached for items, electrodes measured the activity of neurons in their dorsal premotor cortex, a region of the brain that is involved in the perception of movement.

The monkeys were trained to reach for a virtual object on a screen to receive a reward. In some tasks the monkeys had to reach directly for an object, in others they had to reach around an obstacle to get to the target.

Impulsive grab

Moran and Pearce managed to identify the neural activity corresponding with several aspects of the planned movement, such as angle of reach, hand position and the final target location.

The findings could one day allow the design of prosthetic limbs that can be controlled with thought alone, which is “one of the reasons we did the study”, says Moran.

“The two subjects actually used different strategies to perform the task, and we were able to see this in their neural activity,” Moran says. One monkey waited to receive all the information before reaching, but the other reached immediately, even though there was a good chance that an obstacle might appear and the reaching action would need to be rethought.

“If the decoding strategy is a robust finding, then this has wider consequences concerning mind-reading – particularly if we can get equivalent results for more complex strategic differences at higher cognitive levels,” says , a cognitive researcher at Birkbeck, University of London. “However, this is all very speculative.”

Journal reference: Science, DOI: 10.1126/science.1220642