Science Article

SPACE exploration may have a new direction. In the 1960s, humans did the exploring but since the last moon landing in 1972, NASA's only explorers beyond low Earth orbit have been semi-autonomous robots. Now the agency is pondering a third approach, sending astronauts who would remain in orbit around alien worlds and explore via robotic rovers.

Mars Rover

On Earth, human-controlled robots are used for tasks ranging from delicate surgery to exploration of the deep sea. But in space, robotic "telepresence" could be even more promising.

Telerobotics would be orders of magnitude more productive for exploration than semi-autonomous robots like the Mars rovers Spirit and Opportunity, says NASA's George Schmidt, an organiser of the Exploration Telerobotics Symposium earlier this month at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Nothing beats having human cognition and dexterity in the field," he says.

But there is a hitch in trying to control from Earth a robot that's exploring another planet: the huge time lag as the signals travel back and forth. Real-time reactions are needed for it to work. For example, surgeons can perform operations well as long as the robot responds to their actions within about half a second. Greater latencies cause problems.

Latency on Earth is no more than a few hundred milliseconds, but latency between the Earth and moon is about 3 seconds, and that delay is enough to slow telerobotics dramatically, says Daniel Lester of the University of Texas at Austin, another organiser of the symposium. "You could use telepresence to tie a knot in 30 seconds on Earth, but it would take 10 minutes to tie it with 3-second latency."

Latency for signals to Mars is much longer - from 8 to 40 minutes depending on the planets' positions - so real-time control from Earth is impossible. The most plausible way to have robotic telepresence on Mars would be to station astronauts in orbit around the planet.

The first step towards this might be testing out robotic telepresence on Earth with simulated latencies. Rovers on the moon controlled from lunar orbit might come next. Rovers could also be controlled in real-time to explore the far side of the moon, not visited by the Apollo missions. To do this, NASA would have to station astronauts at lunar Lagrangian point L2 - a gravitationally neutral area of space which lies about 60,000 kilometres beyond the moon, in line with Earth.

Mars is a bigger challenge, of course, as is Venus, which is usually considered beyond the scope of human exploration because of its boiling, corrosive atmosphere. A Venus mission could be shorter as it is closer to us than Mars. However, any robots would require extensive modification to survive in Venus's hostile environment and, even then, they would not last the years that a Mars rover might. Nevertheless, having human telepresence would make exploration much more productive than if autonomous robots had to await commands from Earth.

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BELIEVE me, I will try my hardest, but I cannot stop what is going to happen to you in the next 5 minutes. It might be a memory that takes you away... a place that you knew, or an idea you once had. It could be hunger. It could be sex. It could already be happening now.

As you read these sentences, your mind will almost certainly wander at least once - just as mine is drifting as I decide how best to phrase these words so that they hold your attention. In fact, according to some estimates, we may spend nearly 50 per cent of our lives drifting away from the present moment into the world inside our heads.

Sigmund Freud considered such zoning out "infantile"; others feared it could lead to psychosis. Today, we know it is instead the sign of a healthy mind, allowing us to plan for the future by imagining different events, for instance. One particular virtue might even transform how we work, teach children, operate business and nurture ideas.

Drifting, it seems, is a sure sign that our creative juices are flowing. When it comes to arriving at brilliant ideas, the ability to concentrate is overrated. If a person's mind is wandering, they outperform their peers in a range of tasks where flashes of insight are important, from imaginative word games to exercises in original thinking and invention.

The psychologists researching the benefits of daydreaming would never claim to have found a formula for all creative achievement. But their results suggest that learning how to tread the line between focusing in and zoning out could help you to arrive at a breakthrough you might otherwise have missed.

One of the first psychologists to turn their attention to mind wandering was Jonathan Schooler of the University of California in Santa Barbara. One day he was listening to a talk on consciousness when the speaker mentioned the wandering mind. Schooler was so intrigued that he found it tricky to focus. "My mind kept wandering about mind wandering," he says. He found it peculiar that we should enter the state so frequently. "It's the mind escaping from the present," he says, "and we're doing it all the time."

His subsequent experiments helped to show just how often our minds stray off-piste. In one study, volunteers had to read extracts of Leo Tolstoy's War and Peace in his lab. Besides asking them to report whenever they noticed themselves drifting, he would also ask them what they were thinking about at random intervals, and at the end, he tested their comprehension of the text. These measures revealed that people's minds wandered from the words for more than 20 per cent of the time, often without them realising. When faced with other tasks, our capacity for distraction seems even greater; a recent study asking people to report their state of mind at random intervals during the day - via a smartphone app - showed that their attention was wandering from the task at hand a whopping 47 per cent of the time (Science, vol 330, p 932).

Flashes of inspiration

For a long time, this kind of mind wandering would have been considered a serious failing. Instead, the ability to filter out distractions and focus on a task - dubbed executive control - was considered to lie behind smart thinking. Since keeping your train of thought on track is necessary to remember information from moment to moment, short-term "working-memory" capacity is often used to gauge executive control. By this measure, a host of studies have shown that people who can focus well tend to ace analytical problems: they are whizzes at arithmetic and verbal reasoning tasks, and often have a higher IQ. If you wanted to be clever, it seemed that you would need to learn how to concentrate.

Yet there were hints that concentration wasn't all it was cracked up to be. While people with a high level of working memory are good at analytical problems, they tend to struggle on tasks that require flashes of inspiration. "Often the best way to solve a problem is to not focus," says Jennifer Wiley at the University of Illinois in Chicago, who recently reviewed the research (Psychology of Learning and Motivation, vol 56, p 185).

Consider the following brain-teaser, which represents one of the types of puzzle used in these studies. What single word can be added to "High, book and sour" to make another word or phrase? To solve it, you can't simply apply an analytical approach since that would involve crunching through every word in your vocabulary, says Wiley. Instead, the answer often comes out of the blue. Various studies show that people with high working-memory capacity, and therefore good executive control, can find it more difficult to solve these problems than people who are more easily distracted. (The answer, by the way, is "note".)

Update: NuSTAR was successfully launched over the Pacific Ocean at 9 am Pacific Standard Time on 13 June and is now in low Earth orbit

You don't have to be big to hunt black holes. NASA's telescope NuSTAR, which was due to take off from an island in the South Pacific on 13 June, is small enough to fit beneath the belly of an aircraft, even including its launch rocket. Once in orbit, it will unfold to the length of a school bus.

The Nuclear Spectroscopic Telescope Array will be the first telescope to bring high-energy X-rays into focus, letting astronomers map and study the extreme physics around black holes and the explosions of massive stars. Its images of these objects will be 10 times crisper and 100 times more sensitive than those of previous telescopes.

To make such sharp images, the telescope needs to focus X-rays with energies of up to 100 kiloelectronvolts – 10 times as energetic as those sought by previous X-ray telescopes – onto a small area. Visible light telescopes can manage this with a focusing lens relatively close to the eyepiece. But because the X-rays are so energetic, NuSTAR's camera needs to be 10 metres away from the focusing lens.

Ingenious model

NuSTAR is on a tight budget: the whole mission should cost only $170 million. As the team could not afford to launch a 10-metre-long telescope, NuSTAR got scrunched up.

"It's no ordinary-looking telescope," says NuSTAR's principal investigator, Fiona Harrison of the California Institute of Technology in Pasadena. Its "lens" is made up of 133 nested shells of fingernail-thin glass. At launch, the cameras will sit right next to the lenses. A week after it settles into orbit, NuSTAR will push the lenses away from the camera on a thin scaffold.

Harrison, who conceived of NuSTAR in the 1990s, thinks the cheap, ingenious scope could be a new model for budget-bedevilled NASA.

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IT SMELLS, it buzzes, it even dances like a honeybee. In a field in Germany, RoboBee is making its first attempts at speaking to the insects in their own language.

Bees are famous for communicating using the waggle dance - walking forward while rapidly vibrating their rear. In the 1940s, biologist Karl von Frisch realised that the length and angle of the dance correlated with the distance and direction of the food source the bee had just visited. Since then, most apiologists have held that dancers tell their fellows where to find food.

Now Tim Landgraf of the Free University of Berlin in Germany and colleagues have programmed their foam RoboBee, to mimic the dance. RoboBee is stuck to the end of a rod attached to a computer, which determines its "dance" moves. The rod is also connected to a belt which makes it vibrate. Like a real bee, it can spin, buzz its wings, carry scents and droplets of sugar water, and give off heat.

To program RoboBee, Landgraf took high-speed video of 108 real waggle dances, and put the footage through software that analysed the dances in detail (PLoS One, DOI: 10.1371/journal.pone.0021354). The outcome is "the most detailed description so far of the waggle dance", says Christoph Grüter of the University of Sussex in Brighton, UK, who was not involved in the study.

What do real bees think of RoboBee's skills? In a field outside Berlin, Landgraf trained groups of honeybees to use a feeder, which he then closed. The bees stopped foraging and stayed in their hives. There they met RoboBee, which had been programmed with Landgraf's best guess at a waggle dance pointing to another feeder, which the bees had never visited.

The bees responded by leaving the hive, but returned to their old feeders. For now, it looks like RoboBee persuaded them to forage, but failed to communicate where to go. The team is confident RoboBee didn't just scare away the foragers, as honeybees respond to intruders by stinging, not fleeing.

Bees don't always pay attention to the waggle dance, says Grüter. He recently showed that bees become more responsive to other's waggle dances if their private food sources have dried up (Animal Behaviour, DOI: 10.1016/j.anbehav.2011.01.014). This suggests bee communication is even more sophisticated than von Frisch thought: the bees' responses depend on the circumstances.

Lars Chittka of Queen Mary, University of London says previous attempts to make waggle-dancing robots have not panned out, but he is keen to see how RoboBee's more sophisticated dancing fares. Its Achilles heel, though, may be a lack of legs: some studies suggest there is a tap-dance element to the dance.

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LIKE PCs, robots may soon become a key part of our everyday lives, but they present unique communication challenges that PCs do not. So roboticists are turning to people who have already solved many of these problems - actors, animators and dancers.

Nao Robot (France)

MASKED THEATRE The 50-centimetre-tall, white plastic Nao humanoid (see photo) looks adorable. But with such a plain, rigid face - just two big lights for eyes and a pinhole of a mouth - how does the bot do it? Julien Gorrias, a "behavioural architect" at Aldebaran Robotics in Paris, France, which makes the Nao, had solved the same problem in his former life as a masked actor by using expressive body movements. "The whole body was involved in making the mask live," he says. His insights have helped give Nao a tangible personality. "You have to feel like it is someone," he says. "Not a human, but someone."

HRP-4C Robot (Japan)

CARTOONS Humans can often guess what another human is about to do. Pixar's animated characters seem to anticipate their own actions: staring hungrily at a piece of cheese before grabbing it, say, creates the illusion of a thought process that makes a character believable. When the team created animations of the PR2 carrying out a task, onlookers were more certain of their interpretation of the robot's behaviour if its actions portrayed forethought. They also described the robot as more approachable.

INTELLIGENCE The lowest level of robot 'intelligence' is a simple automaton device. My definition of an automatoIn is a device where there is absolutely zero decisions made no matter the given environment. They are simple devices where the action it does is repetitive and automatic. A simple circuit with a motor or a combination of gears and a spring could easily be an automaton.

DANCE Humans naturally move in subtly different ways depending on their emotions and intentions, but unravelling how we do this in order to program it into a robot is tricky. The most important is describe how the timing, strength and angle of a dancer's movement will convey a different inner intention or emotion.

Our braininess is one of our species' defining features. With a volume of 1200 to 1500 cubic centimetres, our brains are three times the size of those of our nearest relative, the chimpanzee. This expansion may have involved a kind of snowball effect, in which initial mutations caused changes that were not only beneficial in themselves but also allowed subsequent mutations that enhanced the brain still further. "You have some changes and that opens opportunities for new changes that can help," says John Hawks at the University of Wisconsin-Madison.

In comparison to that of a chimp, the human brain has a hugely expanded cortex, the folded outermost layer that is home to our most sophisticated mental processes, such as planning, reasoning and language abilities. One approach to finding the genes involved in brain expansion has been to investigate the causes of primary microcephaly, a condition in which babies are born with a brain one-third of the normal size, with the cortex particularly undersized. People with microcephaly are usually cognitively impaired to varying degrees.

Genetic studies of families affected by primary microcephaly have so far turned up seven genes that can cause the condition when mutated. Intriguingly, all seven play a role in cell division, the process by which immature neurons multiply in the fetal brain, before migrating to their final location. In theory, if a single mutation popped up that caused immature neurons to undergo just one extra cycle of cell division, that could double the final size of the cortex.

Take the gene ASPM, short for "abnormal spindle-like microcephaly-associated". It encodes a protein found in immature neurons that is part of the spindle - a molecular scaffold that shares out the chromosomes during cell division. We know this gene was undergoing major changes just as our ancestors' brains were rapidly expanding. When the human ASPM sequence was compared with that of seven primates and six other mammals, it showed several hallmarks of rapid evolution since our ancestors split from chimpanzees (Human Molecular Genetics, vol 13, p 489).

Other insights come from comparing the human and chimp genomes to pin down which regions have been evolving the fastest. This process has highlighted a region called HAR1, short for human accelerated region-1, which is 118 DNA base pairs long (Nature, vol 443, p 167). We do not yet know what HAR1 does, but we do know that it is switched on in the fetal brain between 7 and 19 weeks of gestation, in the cells that go on to form the cortex. "It's all very tantalising," says Katherine Pollard, a biostatistician at The Gladstone Institutes in San Francisco, who led the work.

Equally promising is the discovery of two duplications of a gene called SRGAP2, which affect the brain's development in the womb in two ways: the migration of neurons from their site of production to their final location is accelerated, and the neurons extrude more spines, which allow neural connections to form (Cell, vol 149, p 192). According to Evan Eichler, a geneticist at the University of Washington in Seattle who was involved in the discovery, those changes "could have allowed for radical changes in brain function".

Chimps and other large primates subsist mainly on fruits and leaves. These are such low-calorie foods that the animals have to forage for most of their waking hours. Modern humans get most of their energy from starchy grains or plant roots. Over the past 6 million years our diet must have undergone several shifts, when we started using stone tools, learned to cook with fire, and settled down as farmers.

Some of these changes are hard to date. There is an ongoing debate over what constitutes the first evidence for cooking hearths. And digging sticks, used to unearth tubers and bulbs, do not fossilise. An alternative way of tracking dietary changes is to look at the genes involved in digestion.

A digestive enzyme called salivary amylase plays a key role in breaking down starch into simple sugars so it can be absorbed in the gut. Humans have much higher levels of amylase in their saliva than chimpanzees, and recently it was discovered how this came about.

While chimps have only two copies of the salivary amylase gene (one on each of the relevant chromosome pair), humans have an average of six, with some people having as many as 15 (Nature Genetics, vol 39, p 1256). DNA copying errors during the production of sperm and eggs must have led to the gene being repeatedly duplicated.

To find out when the duplications happened, the gene was sequenced in people from several countries, as well as in chimps and bonobos. "We were hoping to find a signature of selection about 2 million years ago," says Nathaniel Dominy, a biological anthropologist now at Dartmouth College in Hanover, New Hampshire, who led the work. That is around the time our brains underwent significant growth, and one theory is that it was fuelled by a switch to a starchier diet.

But the team found the gene duplications had happened more recently - some time between 100,000 years ago and the present day. The biggest change in that period was the dawn of agriculture, so Dominy thinks the duplications happened when we started farming cereals. "Agriculture was a signal event in human evolution," he says. "We think amylase contributed to it."

It was the advent of agriculture that allowed us to live in larger settlements, which led to innovation, the cultural explosion and, ultimately, modern life. If we consider all the mutations that led to these pivotal points in our evolution, human origins begin to look like a trail of unfeasible coincidences. But that is only because we do not see the harmful mutations that were weeded out, points out John Hawks at the University of Wisconsin-Madison. "What we're left with is the ones that were advantageous." It is only from today's viewpoint that the mutations that give us our current physical form appear to be the "right" ones to have. "It's hindsight," says Hawks. "When we look back at the whole process, it looks like a stunning series of accidents."