Saturday, February 28, 2009
Friday, February 27, 2009
And even the most basic space rockets require multiple stages, whose weight is mostly taken up by oxidisers needed to burn fuel. Rockets launch vertically to minimise the time they spend where Earth's gravity is strongest and shed stages to reduce their weight as they climb.
For decades, engineers have dreamed of a better way: a single-stage-to-orbit vehicle that would be lighter, cheaper, and easy to reuse. A fleet of these vehicles, supporters say, could be almost as easy to maintain as conventional jet planes, reducing the preparation time before each launch from months to days or even hours.
Since most of a rocket's weight is taken up by oxidiser, one logical approach is to save weight by developing an engine that can use oxygen from the atmosphere to burn fuel at least part of the way.
Are we getting any closer to this goal? Last week, the UK firm Reaction Engines announced they had received €1 million from the European Space Agency to develop three key parts for an air-breathing rocket engine. The firm hopes those components could one day help fulfill a decades-old plan to build a space plane called Skylon, which could take off and land on a runway like a conventional jet.
But Skylon isn't the only game in town. Take a look at air-breathing technology and what it could mean for the future of spaceflight.
How do air-breathing engines work?
The basic air-breathing engine uses inlets at the front of the vehicle to suck in air. What happens after that depends on the design.
One common engine is the ramjet, which uses the geometry of the engine to slow air down. But ramjets are only useful at relatively low speeds. At hypersonic speeds - above 5 times the speed of sound, or Mach 5 - the slowed air is too hot to be useful for combustion.
A popular solution to this problem is the scramjet, which does not slow air down very much, but instead quickly mixes the fast-flowing air with fuel together to create thrust. But scramjets are only useful above Mach 5, meaning another system, perhaps a conventional rocket, is needed to propel the plane to hypersonic speeds.
How fast can air-breathing engines travel?
The answer is not yet clear, since the technology has not undergone many tests. But at a certain speed, researchers believe air can't be mixed fast enough with fuel to combust it. That puts a limit on how fast air-breathing engines can go and suggests they will need to depend on rocket power to get that last boost into orbit.
Estimates for the speed limit of scramjets, for example, range from Mach 12 to Mach 20 (depending largely on the type of fuel used), says Mark Lewis, an aerospace engineer at the University of Maryland in College Park. That's still short of the Mach 25 or so needed to reach orbit and means scramjet flights would begin and end with a rocket phase.
What is Skylon's approach?
Skylon's proposed engine would use a heat exchanger to cool incoming air from 1000 °C at Mach 5 to less than -100 °C. Once cooled, the air is mixed with liquid hydrogen and burned.
Unlike scramjets, Skylon is designed to run in air-breathing mode directly from launch up to a speed of Mach 5.5. At an altitude of 26 kilometres, the engine would switch to conventional rocket power and use onboard oxygen to propel the plane into space.
"It's a pretty unique concept," says Mark Hempsell, director of future programmes at Reaction Engines. "I think at the moment it's the only realistic way to make aircraft vehicles that go into space."
The design should be sufficient to power a 43-tonne plane that can loft 12 tonnes of payload into low-Earth orbit, about half what the space shuttle can carry, the firm says.
How far along is the technology?
The most well-developed hypersonic air-breathing engines are small ones that are easily adapted to act as missile propulsion systems.
Two of the longest and fastest hypersonic air-breathing flights on record were made by NASA's X-43, a 5-metre-long scramjet-powered vehicle that accomplished two powered flights lasting roughly 10 seconds at Mach 7 and Mach 10 in 2004.
But that might change soon. Later in 2009, the US Air Force plans to begin test flights of a scramjet called the X-51. A B-52 bomber jet will be used to carry the vehicle to an altitude of 15 km, where it will be released and run for 4 to 5 minutes, accelerating to Mach 6.
Given the range of options, what's the best engine to use?
"As with all these things, the devil is in the details," says propulsion expert Aaron Auslander of NASA's Langley Research Center in Hampton, Virginia.
There may be multiple ways to get to orbit. Picking the best design requires a better understanding of how cost effective and reliable the vehicles will be, Auslander says.
"I think all approaches are on the table," Lewis said. Reaction Engines is "looking at one possible combination of engine system, and there's really a much broader range of options we need to explore before we know what to fly up to orbit," he adds.
Because scramjets might operate over the widest range of speeds, possibly up to Mach 20, Lewis says, they might be the most effective choice: "The farther you can go in the atmosphere, the greater the advantage will be."
But because scramjets would need a rocket to launch, and rockets accelerate too fast for tires, a scramjet plane would either have to launch vertically or on some sort of rail system, says Lewis.
Thursday, February 26, 2009
Spacenet, a provider of network connectivity services via satellites orbiting Earth, has launched a new services program designed to give its channel partners an additional revenue stream and its end users better support during critical need.
Spacenet, whose ConnexStar Reseller channel program is aimed at the small- to med-sized enterprise market, developed the Enhanced Support Program after noticing that certain industries were in need of higher touch support services, said Steve D’Argenio, vice president of small-to-medium enterprise sales at Spacenet.
“Some of our higher-end resellers were starting to have a demand, especially in certain industries, in which our standard support services didn’t meet their critical needs,” he said. “The typical response time for standard support is three days, but in certain industries such as oil and gas, for example, there are critical services needs that require immediate support.”An oil platform in the ocean is one example, he said. “If you’ve got a fire on the rig, you need support immediately, not three days from now.”
The Enhanced Support Program, available now, offers two levels of service levels. Both offer dedicated customer engineering support from 8 a.m. to 6 p.m. Eastern time, dedicated customer network engineering path escalation during non-business hours, access to network utilization reports and a remote annual network health check.
The Silver level includes customer network changes within eight hours, a 10-day remote dispatch service and a 24-month warranty on all hardware.
The Gold level offers customer network changes within two hours, next-business-day provisioning of voice and fax lines, same-day maintenance dispatch service and a 36-month warranty on all hardware.
Channel partners are able to resell the enhanced services as an add-on service to their ConnectStar customers, D’Argenio said.
“The key to this program is this really shows the evolution of how far satellite service has come,” he said. “It can do anything terrestrial networking services can do. It can be the primary connection for any and all applications.
“A few years ago, we wouldn’t even be having a conversation about different service levels. Today, however, it’s a whole new story,” he said.
Wednesday, February 25, 2009
The failure of NASA's Orbiting Carbon Observatory (OCO) is a loss to climate science, but that loss could be doubly compounded if engineers can't correct what went wrong in time for NASA's next climate satellite to fly later this year.
That satellite, known as the Glory mission, is currently set to launch in November, but it's now on hold pending the results of the OCO investigation. Whereas OCO was build to measure greenhouse gases, Glory is designed to study the effects of aerosols on clouds. This has been called the "missing link" of climate science, and it's information that is needed as soon as possible to refine global climate models.
It's well known that clouds reflect sunlight, which has a net effect of making the Earth cooler. It's also known that minute particles called aerosols often become the nuclei around which water droplets form in clouds. But what nobody understands is exactly how much humans are affecting the clouds with all the aerosols we generate through combustion, agriculture and other dust-raising activities.
So a delay in getting Glory off the ground means a delay in filling in this crucial piece of the climate puzzle. But wait - it gets worse.
One of the instruments on Glory is the "Total Irradiance Monitor" (TIM). Its job is to measure the total light output of the Sun to a degree of precision that is simply unachievable on the ground. This is important because sunlight is the key input into global climate and it drives the whole system. The fact that some climate sceptics still site changes in the Sun's energy output as responsible for climate change speaks to the fact that we don't have a good handle on what the Sun is likely to be doing long-term and more data are urgently needed.
Solar irradiance has been measured continuously from space for about the last 30 years. But during the 1980's coverage was insufficient and the calibration is not good between instruments that measured the Sun before and after this period. The deficit has led to disputes and to opposite conclusions about the long-term trend in solar irradiance.
Right now the best instrument for measuring solar irradiance is on the SORCE satellite, which was launched in 2003 and is now well past its nominal mission lifetime.
The TIM instrument on Glory is a descendant of this device and scientists involved with the mission say it's vital for the two instruments to observe the Sun together for at least six months to preserve the continuity of the 30-year solar record. If not, says TIM instrument scientist Greg Kopp of the University of Colorado, "it puts the whole record in jeopardy".
Glory will be launched on the same model of Taurus XL rocket that failed to place OCO into orbit today. The likely cause of the failure - a fairing that decided not to separate - has been established. What is not clear is whether this will require changes that could push back the launch of Glory into 2010 or beyond. Obviously scientists are hoping this will not be the case, and that any changes can be made in parallel with their own preparations for launch. On the other hand, another failure would be disastrous.
Monday, February 16, 2009
The first detailed map of the gravity fields on the Moon's far side shows that the craters are different than those on our side, the near side. The results could reveal more about the Moon as it was billions of years ago, when magma flowed across its surface.
The new gravity map was collected by the Japanese lunar satellite Kaguya, which released two small probes into orbit around the Moon in 2007.
The motions of the three spacecraft, which are sensitive to variations in the Moon's gravity field, were measured by tracking their radio signals.
Crucially, while the main Kaguya spacecraft was on the far side of the Moon and therefore out of direct contact with Earth, one of the small probes relayed its signals to Earth.
The resulting map - the first detailed one completed of the Moon's far side - shows that craters on the far side have a markedly different gravity signature from those on the side that always faces Earth.
That suggests that billions of years ago, there might have been large differences in the temperature or thickness of the Moon's two halves.
"It's fabulous new data," says Walter Kiefer, a planetary geophysicist with the Lunar and Planetary Institute in Houston, Texas, who was not part of the study. "We haven't been able to get a good look at the far side until now."
Most of the large craters on the Moon formed more than 3.8 billion years ago. These were partly filled in by magma that flowed on the surface before the Moon cooled and its geological activity died down.
But a number of craters also seem to have been filled in from below. Researchers believe material from the mantle also rose up in craters, since these are sites where impacts had thinned the Moon's crust.
The new Kaguya measurements reveal some craters on the far side that seem to have been filled only with mantle. These craters have higher-than-normal gravity at the centre, surrounded by a thick ring of low gravity that closely matches the original low elevation of the crater.
It is not yet clear what these new crater measurements suggest about the early Moon. In order for these structures to survive, the lunar far side must have been too cool and stiff to allow the mantle at the craters' centres to smooth out much over time, says team leader Noriyuki Namiki, of Japan's Kyushu University. "The surface had to be very rigid to support these structures," Namiki says.
But Keifer says the low gravity rings could argue for the opposite scenario. The structures in the centres of the craters might be narrow because the top layer of the Moon's far side was too thin and warm to be able to hold up anything larger. Comparing the Kaguya observations with models could help settle the question, Kiefer says.
The Moon's two halves also show other striking differences. NASA's Lunar Prospector, which operated in the late 1990s, found that radioactive elements seem to be concentrated on the near side. The far side also shows less evidence of past volcanic activity.
Sunday, February 15, 2009
The principles of life on Earth may also be applied to life on other planets, with some exceptions. I am including here an extract from Marc D Hauser's book on Moral Minds. He is influenced in turn by the work of Eduard Tinkelpaugh, the 1920's psychologist, famous for his work with examining the intelligence levels of primates and monkeys.
'We do not know what it is like to have a primate experience of expectation, satisfaction and dissatisfaction. Tinkelpaugh proposed that the primate brain has evolved to respond to actions and events and set up expectations about, the causes and consequences to detect violations, using mimicry, learned behaviour and experiences.
I have listed the 5 principles of living as a primate, emanating from the studies of Tinkelpaugh, Darwin and others. These studies involved intelligent animals, primarily primates but occasionally dolphins and birds (Ravens and Jays).
Principle 1 - If an object moves on its own, it is an animal or part of an animal
Principle 2 - If an object moves in a particular direction towards another object or location, the targeted direction picks out or implies the object's goal
Principle 3 - If an object moves 'flexibly', changing direction in response to environmental objects or events, then it is rational
Principle 4 - If one object's action is followed closely by a second object's action, the second object's action is perceived as a socially intelligent response
Principle 5 - If an object is self-propelled, goal-directed and flexibly responsive to environmental constraints and events, then the object has the potential to cause harm or comfort to other similar objects.
Friday, February 13, 2009
Thursday, February 12, 2009
'Dark' comets may pose threat to Earth
A composite of images from NASA's Deep Space 1 spacecraft shows features of comet Borrelly's nucleus, dust jets escaping the nucleus and the cloud-like "coma" of dust and gases surrounding the nucleus. False colour is used to reveal details of the jets and coma (Image: JPL / NASA)
SWATHES of dark comets may be prowling the solar system, posing a deadly threat to Earth.
Hazardous comets and asteroids are monitored by various space agencies under an umbrella effort known as Spaceguard. The vast majority of objects found so far are rocky asteroids. Yet UK-based astronomers Bill Napier at Cardiff University and David Asher at Armagh Observatory in Northern Ireland claim that many comets could be going undetected. "There is a case to be made that dark, dormant comets are a significant but largely unseen hazard," says Napier.
In previous work, Napier and Janaki Wickramasinghe, also at Cardiff, have suggested that when the solar system periodically passes through the galactic plane, it nudges comets in our direction (New Scientist, 19 April 2008, p 10).
These periodic comet showers appear to correlate with the dates of ancient impact craters found on Earth, which would suggest that most impactors in the past were comets, not asteroids.
Now Napier and Asher warn that some of these comets may still be zipping around the solar system. Other observations support their case. The rate that bright comets enter the solar system implies there should be around 3000 of them buzzing around, and yet only 25 are known.
We may not see them, say the pair, simply because they are too dark.
Such dark comets are not unheard of. They occur when an "active" comet's reflective water ice has evaporated away, leaving behind an organic crust that only reflects a small fraction of light.
In 1983, Comet IRAS-Araki-Alcock passed by Earth at a distance of 5 million kilometres, the closest known pass by any known comet for 200 years. It was spotted only two weeks ahead of its closest approach. "It had only 1 per cent of its surface active," says Napier. Comet Borrelly, visited by NASA's Deep Space 1 probe in 2001, was found to have extremely dark patches over much of its surface.
"There may be merit to this idea," says Steve Larson of the University of Arizona's Catalina Sky Survey in Tucson, one of the main contributors to Spaceguard.
Clark Chapman at the Southwest Research Institute in Boulder, Colorado, is sceptical, but points out that such dark comets "would absorb sunlight very well" and so could be detected by the heat they would emit.
Satellite collision creates copious space junk
Two space satellites smashed into each other on Tuesday in an unprecedented orbital accident. Government agencies are still assessing the aftermath, but early radar measurements have detected hundreds of pieces of debris that could pose a risk to other spacecraft.
As first reported by CBS News, a defunct Russian Cosmos satellite and a communication satellite owned by the US firm Iridium collided some 790 kilometres above northern Siberia on Tuesday.
"This is the first time that two intact spacecraft have accidentally run into each other," says Nicholas Johnson, chief scientist of NASA's Orbital Debris Program Office in Houston, Texas.
Thursday, February 5, 2009
Auroras: What powers the greatest light show on Earth?
See New Scientist's gallery of auroras
A few times a day, a gigantic explosion shakes the Earth's magnetic shield, triggering a chain of events that lights up the polar skies with dazzling auroras. These explosions are substorms, and how they happen has long been a mystery. Until now, no one has been able to explain how they gather the energy to create such spectacular displays, or what happens to trigger them.
Now a flotilla of NASA satellites is finally providing answers. They could help us understand not only one of nature's greatest spectacles, but also help predict more serious space weather, which can endanger satellites and astronauts, and even scramble electrical systems on Earth.
The northern and southern lights have fascinated people throughout human history, and there has been no shortage of attempts to explain them. Galileo described these auroras as sunlight reflected in vapours rising from the Earth, while Descartes proposed reflections from ice crystals instead. In the late 1600s, Edmond Halley was the first to correctly link the aurora to the Earth's magnetic field, though it wasn't until the 1950s that scientists confirmed that the display is created when electrons are funnelled by magnetic fields into the upper atmosphere.
Auroras, substorms and more hazardous kinds of space weather all begin with the solar wind - a thin, hot gas of charged particles ejected from the sun, laced with magnetic fields and threaded with electric currents. This magnetic hurricane is blowing over the planet at 1.6 million kilometres per hour, but we don't feel so much as a breeze. That's because most of it is deflected by the Earth's magnetic field, which maintains a zone of relatively calm weather around the planet, called the magnetosphere. As the solar wind blows past the Earth, it pushes and stretches this protective shield out on the night side of the planet, like hair blown in the wind.
Despite this protection, the solar wind buffets and stirs up the magnetosphere, sending high-energy particles showering into the Earth's upper atmosphere. There they light up the gases like a neon tube, creating an aurora that appears as a slowly shifting curtain of green light as the charged particles smash into oxygen atoms. These "quiet auroral arcs" are usually quite faint. "People will often not realise there's an aurora. The sky will look a bit weird maybe, with a diffuse glow," says Eric Donovan of the University of Calgary, Alberta, who monitors the aurora borealis in Canada.
When a substorm rips through the magnetosphere, though, unleashing the energy of a few megatons of TNT, the effects are unmistakable. Magnetic fields whip through space, the electrical currents that circle the magnetosphere thrash wildly, and the aurora is transformed into a much brighter and more dynamic display that sweeps across the sky for 10 to 15 minutes. "It is not uncommon to get a hundred or thousandfold increase in brightness," says Donovan. The aurora also becomes more colourful, as high-energy electrons smash into molecules of the air, exciting red and green light from oxygen and blue from nitrogen.
During a substorm, it is not uncommon to get a hundred or thousandfold increase in brightness
It was already known that what makes the difference between subtle auroral arcs and the dazzling light shows caused by substorms is the direction of magnetic field in the solar wind. Most of the time the field aligns with that of the Earth, which allows the solar wind to flow uninterrupted around the planet. When the two fields point in opposite directions, though, they can become connected, and that loads the magnetosphere with the energy needed to create a substorm. It was not clear exactly how this happened, however.
Satellites such as the Geotail mission, led by the Japan Aerospace Exploration Agency, have helped tell part of the story. Since 1992, Geotail has ranged around the long tail of the Earth's magnetic field, studying its interaction with the solar wind. But a single spacecraft can only tell what's happening at one point; it can't get a big picture of the rapid and complex changes that shake the whole magnetosphere. "In the past, we only had 'pinprick' observations," says David Sibeck of NASA's Goddard Space Flight Center in Greenbelt, Maryland.
To broaden this view, NASA launched a flotilla of satellites, collectively named THEMIS, in February 2007 to catch substorms as they happen. The five small spacecraft orbit the Earth like juggled balls, each following a different looping path, so when something interesting happens in the magnetosphere there's a good chance that they will be in a suitable arrangement to see it.
Three months after launch, THEMIS encountered the beginnings of a substorm. "We had five spacecraft lined up in a row perpendicular to the outer boundary of Earth's magnetic field, some just inside, some just outside," says Sibeck.
This position turned out to be the perfect spot to answer one of the mission's questions: how the solar wind pumps energy into the magnetosphere to power a substorm.
THEMIS's recordings revealed changes in the Earth's magnetic field as the solar wind connected with the magnetosphere. A bulge of twisted magnetic fields formed and slid along its boundary, towards the night side of the Earth. The team recognised this as a phenomenon called a flux rope, which some researchers had suggested would be linked to substorms.
Flux ropes connect the magnetic fields in the solar wind with those of the magnetosphere and the two become entwined, linking Earth's domain with that of the sun. This allows high-energy particles to stream in, loading the magnetosphere with pent-up energy
As the solar wind blows over the Earth, it pulls on its end of the flux rope, dragging the rope and its magnetic fields away from Earth's day side and out into the tail of the magnetosphere.
As more and more flux ropes form and are pulled into the tail, the day side of the Earth loses more and more of its magnetic field. That does not go on forever, of course. "It would completely deplete the day-side magnetic field", says Vassilis Angelopoulos of the University of California in Los Angeles, who heads the THEMIS mission. Earth's shield would disappear, leaving us exposed to carcinogenic cosmic rays. Over geological timescales, the atmosphere might even be stripped away by the solar wind.
Clearly, and luckily for us, that doesn't happen. Instead, after a few hours of building magnetic tension, a substorm strikes. Several things happen almost simultaneously: the tail snaps, hurling plasma towards the Earth, and the electric current that girdles the Earth is disrupted. But which of these triggers the substorm and the resulting aurora? To find out, the THEMIS researchers needed to know which happens first.
There are two competing theories. One school of thought has it that the impetus must come from the powerful electric current that flows around the magnetosphere about 60,000 kilometres up. The motion of magnetic fields drives this current, as in a dynamo, and it is known to be boosted when magnetic field is added to the tail. Does it get so strong that it becomes unstable and showers the atmosphere with high-energy electrons?
The other theory is that the trigger comes from the tail itself. As more magnetic field is added to it, the tail gets compressed tighter and tighter. Around the pinched core of the tail, these magnetic fields point in opposite directions, one running outwards from the north pole and the other running in towards the south pole. As these two field lines are stretched and squeezed by the solar wind, perhaps the two opposing fields spontaneously reconnect, cutting the tail in half and sparking a substorm
As luck would have it, on 26 February 2008, a substorm hit while the THEMIS flotilla was strung out on the night side of the Earth, straddling the region where the current would be disrupted and also where the tail would be expected to snap and reconnect. It was the perfect opportunity to settle the argument.
The first thing the satellites recorded was the tail of the magnetic field snapping off and reconnecting, suggesting that substorms do start with changes in this area. Case closed? Not quite. There was also a big surprise for the THEMIS team. Angelopoulos expected that the break in the tail would first destabilise the current encircling the planet, which in turn would spray electrons down to Earth to cause the aurora. Instead, the aurora began to intensify about a minute after reconnection in the tail, and, crucially, before the disruption of the ring current. "I was shocked," says Angelopoulos. "We never expected that within a minute you would see the aurora light up."
Not everyone is convinced that the team's findings, settle the matter, however. Indeed, Anthony Lui of Johns Hopkins University in Baltimore, Maryland, disputes the whole sequence of events. He thinks that Angelopoulos and his team have misinterpreted the THEMIS data and that reconnection in the tail happens later. "Then the sequence would be opposite to that stated in the Science article, implying that current disruption is the trigger of substorms instead," Lui says.
Although the THEMIS team have since recorded several more substorms, with the same results, Lui maintains that the spacecraft have never been in quite in the right positions to give definitive results. Angelopoulos has decided to alter their orbits to address this problem. Over the coming months, that may remove any remaining controversy about what sparks substorms and perhaps explain how their auroras appear so quickly.
The mission might also illuminate the link between substorms and full-blown geomagnetic storms, which can cause more than a pretty display. These storms are caused by violent outbursts from the sun and can play havoc with satellites, scramble GPS signals, endanger astronauts and even blow power lines on Earth. During a geomagnetic storm there are typically several substorms, but how the two are connected is unclear. So far during the mission, solar activity has been low, but it should increase over the coming year or so, giving THEMIS a chance to watch a much larger storm unfold.
Angelopoulos will be looking forward to it, and not just for the scientific opportunities. Perhaps surprisingly for someone who spends much of his time pondering substorms, Angelopoulos has seen very few with his own eyes. That is part of his motivation to understand them. "I want to go and watch them, so I'm working on predictive models," he says. "With a good model of how the trigger mechanism works, it should be possible to predict the onset of a substorm to within minutes, he says. "Then I can run outside."
Scott Wiltermuth of Stanford University in California and colleagues have found that activities performed in unison, such as marching or dancing, increase loyalty to the group. "It makes us feel as though we're part of a larger entity, so we see the group's welfare as being as important as our own," he says.
Wiltermuth's team separated 96 people into four groups who performed these tasks together: listening to a song while silently mouthing the words, singing along, singing and dancing, or listening to different versions of the song so that they sang and danced out of sync. In a later game, when asked to decide whether to stick with the group or strive for personal gain, those in the non-synchronised group behaved less loyally than the rest (Psychological Science, vol 20, p 1).
Meanwhile, the powerful unifying effects of propaganda images are being explored by Charles Seger at Indiana University at Bloomington. His team primed students with pictures of their university - college sweatshirts or the buildings themselves - then asked how highly they scored on different emotions, such as pride or happiness. The primed students gave a strikingly similar emotional profile, in contrast with non-primed students (Journal of Experimental Social Psychology, DOI: 10.1016/j.jesp.2008.12.004).
Interest in the idea of a herd mentality has been renewed by work into mirror neurons - cells that fire when we perform an action or watch someone perform a similar action. It suggests that our brains are geared to mimic our peers. "We are set up for 'auto-copy'," says Haidt. Interest in the idea of a herd mentality has been renewed by research into mirror neurons
Neurological evidence seems to back this idea. Vasily Klucharev, at the Donders Centre for Cognitive Neuroimaging in Nijmegen, the Netherlands, found that the brain releases more of the reward chemical dopamine when we fall in line with the group consensus (Neuron, vol 61, p 140). His team asked 24 women to rate more than 200 women for attractiveness. If a participant discovered their ratings did not tally with that of the others, they tended to readjust their scores. When a woman realised her differing opinion, fMRI scans revealed that her brain generated what the team dubbed an "error signal". This has a conditioning effect, says Klucharev: it's how we learn to follow the crowd
Wednesday, February 4, 2009
Images from past and current Mars probes are combined to create a global, three-dimensional exploration tool in the new version of Google Earth (Illustration: Google)
Mars enthusiasts can fly from the towering peak of Olympus Mons to Mars Pathfinder's peaceful resting place in an add-on to the latest version of the desktop application Google Earth, which was released on Monday.
The new Mars map amasses some 1000 gigabytes of data from a range of Mars probes, including NASA's Viking orbiters, Europe's Mars Express orbiter, and six landers, such as NASA's twin rovers, to create a three-dimensional view of the planet at a wide range of scales.
"What we've done is bring all that information into one single, easy-to-use platform," says Matthew Hancher of NASA's Ames Research Center in Moffett Field, California. "Everything that's ever gone to Mars has been put together to give us this unified view of the planet."
The new tool is accessible enough to appeal to a wide audience, but Hancher hopes the tool will also help researchers by allowing them to determine what data is available - such as infrared images and mineral maps made by orbital spectrometers - for particular regions of interest.
The software is intended to be interactive, allowing users to draw lines, add text, embed videos, and add images. Researchers may also add new content, which must be encoded in a language called KML in order to be properly overlaid on the globe.
So far adding new data to the Mars layer is not automated, and only a few hundred images from the HiRISE camera aboard NASA's Mars Reconnaissance Orbiter - the most powerful camera ever sent to another planet - have been added, Hancher says.
The new software is an outgrowth of Google Mars, an online tool that allows users to view two-dimensional maps of the Red Planet, pieced together from images taken by Mars Global Surveyor and Mars Odyssey.
Read more about how to use the new Mars features in the Google Earth Blog.
Sunday, February 1, 2009
Tapetails (pictured, top) live in shallow waters and are named for the long streamers that trail behind them. Whalefish and bignoses are both deep-sea fish, but while whalefish (middle) lack scales and have huge jaws, bignoses (bottom) have long nasal organs and immobile jaws, and live off energy stored in their gigantic livers.
Nobody thought these groups were related. "The differences were so extreme," says marine biologist David Johnson of the Smithsonian Institution in Washington DC.
Then a study found that whalefish and tapetail mitochondrial DNA is virtually identical, prompting Johnson to re-examine museum specimens. This revealed one in the process of changing from a tapetail into a whalefish. Specimens intermediate between tapetails and bignoses were collected in 2007, and together with more DNA analysis this proved that the three families are really one.
A "tapetail" larva grows up to be a "whalefish" female or "bignose" male. Johnson claims this is the most extreme metamorphosis ever seen in a vertebrate.