Update: RadioAstron successfully blasted into orbit from Baikonur at 6.31 am local time on Monday morning

Original article, 22:14 16 July 2011

A Russian space telescope conceived during the Cold War is set to launch on Monday. When it reaches an orbit that will extend almost as far as the moon, the mission will sync up with radio antennas on the ground, effectively forming the biggest telescope yet built, with a “dish” spanning almost 30 times the Earth’s diameter.

¸é˛ą»ĺľ±´Ç´ˇ˛őłŮ°ů´Ç˛Ô’s roots extend back more than three decades, but the mission lost momentum when the Soviet Union collapsed in 1991. “For 20 years it was always five years away,” says collaborator of the National Radio Astronomy Observatory in Charlottesville, Virginia.

Now, at long last, the spacecraft is poised to launch from Kazakhstan’s Baikonur cosmodrome at 0231 GMT on Monday.

At 10 metres, ¸é˛ą»ĺľ±´Ç´ˇ˛őłŮ°ů´Ç˛Ô’s antenna is small compared to Earth’s , which span 100 metres or more. But when its signals are combined with those of telescopes on the ground – a technique called interferometry – the resulting observations are as sharp as those produced by a single telescope with a dish as wide as the maximum distance between the component antennas.

Eagle eye

This strategy has been used for decades to create radio telescopes the size of the Earth, and in 1997 the Japanese Space Agency launched the first space telescope dedicated to radio interferometry, .

With an orbit that will extend more than 10 times as far from Earth as HALCA, out to some 350,000 kilometres, RadioAstron promises to capture detail that is more than 10 times as fine. At its best, RadioAstron will be able to resolve points separated by an angle of just 7 microarcseconds, about 10,000 times the resolution of the Hubble Space Telescope.

“There has never been a radio telescope that has been sent so far from the Earth,” says Yuri Kovalev, a team leader at the in Moscow, Russia, which is managing the mission.

Unfolding petals

If all goes well, a Zenit-2SB rocket will help carry the spacecraft into an oblong orbit that will extend from 10,000 kilometres to more than 300,000 kilometres from Earth. Once in orbit, 27 “petals” made of carbon fibre will unfold to create the 10-metre-wide antenna. Over the course of the telescope’s five-year mission, the moon’s gravity will tug on the telescope, pulling it up to 390,000 kilometres from Earth.

After a few months of check-out, the team will begin to coordinate observations with telescopes on the ground, including two 100-metre radio telescopes – in , West Virginia, and , Germany, and the 305-metre in Puerto Rico.

RadioAstron will zoom in with unprecedented detail on objects such as the nearby galaxy M87, which is spewing relativistic particles from a colossal black hole at its core. By some estimates, the telescope could be used to image near the black hole’s event horizon – the boundary around which nothing can escape the black hole’s gravity. This could reveal new information about how supermassive black holes accelerate matter to near light speed.

Precision cosmology

The telescope will also be able to register the radio waves emitted by water masers, clouds of water molecules that emit microwave radiation, in the discs of galaxies. This motion can be used to study the rotation rate of the galaxies and measure their distance from Earth. When combined with observations of how fast the galaxies are moving, astronomers can use the galaxy distances to calculate the present-day expansion rate of space and the . RadioAstron may be able to pinpoint the masers’ positions more precisely than previous measurements, says of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

The telescope will also use the lighthouse-like radio emission from pulsars, the spinning remains of exploded stars, to reveal how dust and gas is distributed around the stars.

The project faces some challenges, chief among them the flood of data – some 144 megabits per second – that the dish will collect. “There’s so much data coming to RadioAstron that you can’t store it on board. The data needs to be transported continuously to the ground,” says Kellermann, who co-chairs ¸é˛ą»ĺľ±´Ç´ˇ˛őłŮ°ů´Ç˛Ô’s International Advisory Committee.

So far, only one antenna, a 22-metre dish in the town of Pushchino, south of Moscow, has been set up to receive signals from the spacecraft. Unless other receiver stations can be set up, a good fraction of data the telescope will collect will be lost. The team hopes more receiving stations will be set up as the mission moves forward.

The problem is just the latest blow for NASA’s ultra-sensitive (JWST), which is expected to launch late and run over-budget.

JWST has a 6.5-metre mirror, which is nearly three times as wide as the mirror on the . The telescope could glimpse the universe’s first stars and galaxies.

But in December of the University of Arizona in Tucson and colleagues found that roughly 2 per cent of pixels in a detector destined for JWST’s Near Infrared Camera (NIRCam) were transmitting signals although no light was hitting them. That’s four times as many “hot pixels” as there were when the detector was analysed in 2008.

The researchers later found that the problem affects four of the camera’s five long-wavelength detector arrays. “We don’t know what is happening, and we don’t know if there’s a way to reverse it or slow it down,” says Rieke, principal investigator for the NIRCam. “Until we understand the root cause, I think we’re all going to be quite nervous.”

Latest setback

NASA allows no more than 5 per cent of a detector’s pixels to be hot by the end of the telescope’s five-year space mission. At this rate, the detectors may exceed this limit before the telescope even leaves the ground, says Rieke.

The pixel problem follows a series of setbacks for JWST. In November 2010, an independent review panel predicted that JWST is unlikely to launch before September 2015, more than a year later than planned, and will cost $1.5 billion more than expected.

NASA has set up a review board to analyse the detector problem and discuss solutions. “It’s too early to speculate on what the root cause is or what we’re going to do to fix it,” says JWST programme director Rick Howard. He says it may be a month or more before the expert board comes to a conclusion.

The bizarre bouncing arises because quantum particles behave like waves rather than single, defined points. When the wave-like particles approach a surface, they swim into the surface’s electric field. Even if they are attracted by this field electrically, the sudden change in environment can cause them to rebound before actually hitting the surface, like water waves ramming together in front of a speeding boat’s hull.

“Physics students learn this quantum reflection in their quantum mechanics course, but they might doubt that it’s happening in the real world,” says Bum Suk Zhao of the Fritz Haber Institute in Berlin, Germany.

Zhao and colleagues have shown that the effect does happen with molecules.

Dimers and trimers

The team cooled helium to about 0.001° C above absolute zero. At that temperature, some of the atoms in the gas clumped together to form fragile molecules containing two or three helium atoms, called dimers and trimers, respectively. A stream of these cooled atoms and molecules was then shot at a piece of aluminium-coated glass at a speed of 300 metres per second.

Although the helium moved quickly, it was sent towards the target at a glancing angle – just 0.02° – meaning it would impact with very little energy. The team found that the dimers and trimers rebounded when they were still tens of nanometres away from the target’s surface.

They also stayed intact afterwards, without breaking up into individual helium atoms. “When we saw the dimer reflection we were surprised, because it is very fragile,” Zhao says. The helium atoms in a dimer are bound together with 100 million times less energy than two bound hydrogen atoms, a connection so tenuous it has been dubbed “the weakest bond”.

Molecules such as helium dimers could act as test particles to help physicists better understand the physics of surfaces. That could help refine “atom optics” devices like atomic clocks that exploit the wave nature of atoms, and could help develop “chips” that would use cold atoms for quantum computing.

“These are tough experiments to do, and these are the experiments that one has to do in order to further develop the technology related to cold atoms,” says of the University of Vermont in Burlington.

Journal reference: , vol 331, p 892

The device is part of a growing family of metamaterials – structures designed to steer light along curved paths. They have already been used to make objects appear invisible and to .

Wei Xiang Jiang and Tie Jun Cui at Southeast University in Nanjing, China, have created a structure that changes the way radio waves interact with a copper cylinder so that it appears to be composed of another material altogether.

Copper conducts electricity well and reflects incoming radio waves, giving it a bright radar signature. To alter this behaviour, the team built a device made of 11 concentric rings of circuit boards etched with small metal-lined channels that prevent electromagnetic waves reflecting away. Instead, they guide the waves in a direction that the researchers choose specifically to make the hidden object appear to have different electrical properties.

Placed around a copper cylinder, the arrangement created the illusion that the cylinder was made of a dielectric, a class of materials including porcelain and glass that do not conduct electricity and are more transparent to radio waves.

The illusion only worked when the cylinder was viewed from the side; what’s more, the imaginary object it generated was the same size as the original. Future designs would have to account for all three dimensions, and might produce an illusion quite different from the object they disguise.

“In principle, this technology could be used to make an illusion of an arbitrary shape and size,” says Cui, whose team created an electromagnetic “black hole” for light in 2009. Similar illusion devices could eventually be used for stealth technology: for example, to “convert the radar image of an aircraft into a flying bird”, Cui says.

The work, which is published in Physical Review E, is still at an early stage, however. At 45 millimetres, the team’s illusion device is three times as wide as the cylinder it disguised. “Their device is still fairly bulky relative to the original object, so further work needs to be done before a real device can be deployed,” says of Imperial College London.

Although invisibility devices were invented first, the illusion technology might win the race to be put to practical use. “It is easier to falsify something than to hide it,” Pendry says.

The team next plans to explore ways to design devices with more complex shapes.

Journal reference: (DOI:10.1103/PhysRevE.83.026601)

How does a nose generate the signals that the brain registers as smell? The conventional theory says it’s down to the different shapes of smelly molecules. But fruit flies have now distinguished between two molecules with identical shapes, providing the first experimental evidence to support a controversial theory that the sense of smell can operate by detecting molecular vibrations.

The noses of mammals, and the antennae of flies, are lined with different folded proteins that form pocket-shaped “receptors”. It has been generally assumed that a smell arises when an odour molecule slides into a receptor like a key in a lock, altering the receptor’s shape and triggering a cascade of chemical events that eventually reach the brain. But this “shape” theory has limitations. For one, it can’t easily explain why different molecules can have very similar smells.

In 1996, Luca Turin, a biophysicist now at the Massachusetts Institute of Technology, proposed a solution. He revived a theory that the way a molecule vibrates can dictate it odour, and came up with a mechanism to explain how this might work.

His idea was that electrons might only be able to pass across a receptor if it was bound to a molecule that vibrated at just the right frequency. Ordinarily, the energy needed for the electron to make this journey would be too great, but the right vibrational energy could prompt a quantum effect in which the electron “tunnels” through this energy barrier, and this would then be detected and registered as a particular smell (see diagram).

Perfumed maze

If this is correct, animals should be able to distinguish between molecules of the same shape but with bonds that vibrate at different frequencies. That is the case for chemicals in which atoms of deuterium – a hydrogen isotope whose nucleus contains a neutron as well as the normal proton – replace ordinary hydrogen atoms. The extra neutrons don’t change the molecule’s shape, but they double the mass of the hydrogen atoms and so alter the frequencies at which the molecule vibrates.

Past tests on humans failed to turn up strong evidence that people can distinguish normal odour molecules from their “deuterated” counterparts. But now Turin has teamed up with of the Alexander Fleming Biomedical Sciences Research Center in Vari, Greece, to test the idea on fruit flies, which can easily be trained to recognise different odours.

Their team initially placed fruit flies in a simple maze that let them choose between two arms, one containing a fragrant chemical such as acetophenone, a common perfume ingredient, the other containing a deuterated version. If the flies were sensing odours using shape alone, they should not be able to tell the difference between the two. In fact, the researchers found that flies preferred ordinary acetophenone. They also showed a preference for ordinary versions of octanol and benzaldehyde over deuterated versions.

The team also found they could use mild electric shocks to either reinforce or reverse this preference for non-deuterated molecules in general. This suggests the flies may be able to sense the vibrations characteristic of the bonds linking deuterium to carbon atoms.

Quantum detectors

“At the outset, I thought this could never work,” Skoulakis says. “During the course of the experiment we convinced ourselves.”

Turin sees the results as a “vindication” of his theory, at least in flies. “My theory was described as impossible physically, implausible biologically, not supported by evidence,” he says. “This is a clear indication that some component of fruit fly olfaction is sensing vibrations.”

The experiment “really supports this idea that fruit flies have the ability to be quantum detectors”, says of the University of Houston in Texas, whose lab just started studying isotope detection in fruit flies.

How large a role molecular vibration sensing plays is unclear. of Rockefeller University in New York City agrees that the experiment suggests fruit flies can distinguish one isotope from another but says the assumption that this is due to vibrations is an “over-interpretation”.

Dog sniffing

Turin’s original tunnelling idea was based on a type of odour receptor in humans that fruit flies don’t appear to have. “The logic of using the fly to test the vibration theory escapes me,” she says.

Turin and Skoulakis are now planning genetic studies that might help pinpoint the amino acids on receptors that play a key role in isotope detection. This could help piece together a specific tunnelling mechanism for flies.

Could humans also differentiate between isotopes? In 2004, Vosshall and Andreas Keller found that . But Skoulakis says flies might be more sensitive to the effects of quantum vibrations. He says that giving mild shocks to humans, which wasn’t done in the previous experiment, may help their brains pick up on differences.

Experiments are planned in another type of mammal. Several years ago John Sagebiel of the University of Nevada, Reno and of the Desert Research Institute in Reno, Nevada, found that their pet dog, an Australian shepherd, seemed to be able to tell apart ordinary acetophenone and a deuterated version. They are now applying for funding to see if these informal results hold up in other dogs.

Journal reference: , DOI: 10.1073/pnas.1012293108

The dense core of a nearby collapsed star is undergoing a rapid chill, providing the first direct evidence that such stars can produce a superfluid of neutrons – a state of matter that cannot be created in laboratories on Earth.

Neutron stars are the remnants of exploded stars. Their cores are so dense that atomic nuclei dissolve, and protons and electrons combine to form a soup dominated by neutrons.

If conditions are right, these neutrons ought to be able to pair up to form a superfluid – a substance with quantum properties that mean it flows with zero friction. Superfluids formed in laboratories can do bizarre things such as creep up the walls of a cup, or remain still even while their container is made to spin.

It has long been assumed that neutrons in the cores of neutron stars become superfluid, but without any direct evidence that they do so. That changed in 2010, when astrophysicists Craig Heinke and Wynn Ho of the 330-year-old neutron star at the heart of the dusty supernova remnant Cassiopeia A.

Neutrino release

These measurements show the star has dimmed by 20 per cent since it was discovered in 1999, corresponding to an estimated temperature drop of 4 per cent. “It’s enormously fast cooling,” says Dany Page of the National Autonomous University of Mexico in Mexico City.

Now Page and colleagues have calculated that if a fraction of the neutrons in the core are undergoing a transition to superfluidity.

When neutrons pair up to form a superfluid they release neutrinos which should pass easily through the star, carrying significant amounts of energy with them. This would cause the star to cool rapidly, argue Page’s team.

A second group that includes Heinke and Ho has also attributed the neutron star’s rapid drop in temperature to .

Cooling slows

of the University of Maryland in College Park finds this reasoning convincing, but points out that both groups of astronomers relied on particularly complex models to estimate the temperature of a star from its brightness, rather than measuring the temperature directly . “Although I would personally bet that these two groups have the correct interpretation, we might not have enough information to say this with certainty,” he says.

Astronomers could get firmer evidence for superfluidity by monitoring the neutron star over the coming decades. As a greater fraction of it becomes superfluid, its rate of cooling should slow.

There is little chance of creating a soup of superfluid neutrons on Earth. Although particle colliders can create dense fireballs of matter, the temperatures are too high to mimic the interiors of neutron stars. Superfluids made in laboratories are usually composed of chilled helium atoms.

Page and his team’s conclusions are due to be published in , while Heinke, Ho and colleagues will be publishing their work in .

References: and

If you thrill at the discovery of new exoplanets, hold tight. A sextuplet alien solar system has been glimpsed in exquisite detail, revealing six planets of varying mass, five of which are packed closer to one another than in any planetary system seen before.

“We think this is the biggest thing in exoplanets since the discovery of 51 Pegasi b, the first exoplanet, back in 1995,” of NASA’s Ames Research Center in Moffett Field, California, told reporters earlier this week.

The six newly found planets orbit a star dubbed Kepler-11, which sits some 2000 light years from Earth. They were glimpsed by NASA’s Kepler telescope, which has been staring at the same patch of sky since its launch in March 2009.

The Kepler telescope captured periodic dips in Kepler-11’s brightness, created when planets pass between the star and Earth. These “transits” allow astronomers to measure a planet’s size.

But Kepler-11’s inner five planets – which all orbit closer to their host than Mercury does the sun – are close enough to one another to exert gravitational tugs that continually alter the length of time it takes for each planet to orbit the star. These timing variations allowed Lissauer and a team of colleagues to estimate the planets’ masses, which range from 2 to 14 times the mass of the Earth (shown in the bottom row of this image).

Planetary puzzle

The researchers then used this information to estimate the density of the innermost planets and found that all are less dense than the Earth. Some may have massive hydrogen atmospheres, they say, while others may contain significant amounts of water.

Future observations should pin down the planets’ densities, which could help astronomers discern whether they formed close to or far from their present locations. Either scenario could present a challenge for planet formation models, says of the University of Colorado, Boulder.

These models suggest the region close to Kepler-11 might have been hot enough to keep ice vaporised and blow away nearby gas, preventing the growing planets from capturing as much gas and ice as they seem to have.

Conversely, if the planets formed farther out, models suggest they would have exerted strong tugs on their neighbours as they migrated inwards, sending the six planets into orbits on differing planes. Yet Kepler-11’s planets all seem to orbit in a single plane. “That certainly makes for a puzzle about how the system was set up,” Armitage says.

Testing laboratory

Solving that puzzle could refine our understanding of how planets form. “It’s a pretty big deal,” says of Columbia University in New York. “I think this will be one of the best laboratories for testing planetary formation theories.”

The discovery of the Kepler-11 planets comes against a backdrop of recent exoplanet excitement.

Researchers just announced a fresh haul of data on exoplanets, including 54 planet candidates in the habitable zones of their stars, also captured by the Kepler telescope. And last September, the first alien planet capable of hosting life on its surface was glimpsed.

Although its existence has yet to be confirmed by further data, scientists have been using climate models to figure out whether its climate is life friendly. An even bigger prize would be the discovery of an Earth twin – a planet the size and temperature of our own.

Journal reference:

This article has been updated since it was first posted.

Can the way the universe behaves at the tiniest scales be recreated in the laboratory?

Physicist Igor Smolyaninov of the University of Maryland in College Park has a recipe for cooking up a lab-scale version of a “quantum foam”, the choppy substance that constitutes space-time in some theories of quantum gravity.

According to these theories, space-time may appear smooth and curved, but zoom in, and it is actually made of virtual black holes, each just 10^-35 metres wide, which flit in and out of existence.

To mimic this structure, Smolyaninov suggests exploiting “critical opalescence”. At certain temperatures, some combinations of fluids can roil and form a rough mixture of separate patches. As photons travel at different speeds through each fluid, light is refracted, or bent, at the boundaries between the patches and the mixture ends up opaque.

Transient patches

Immersing a mesh of metal wires into such a mixture accentuates these speed differences. Smolyaninov calculates that the differences could be made so great that incoming light would bounce repeatedly around the interior of the patches, . Dependent on fluctuations in heat, such “black holes” would be transient like those in a quantum foam.

It’s not clear what this artificial foam could tell us about quantum gravity, but Smolyaninov says that, at the very least, it could allow physicists to “ask more intelligent questions about how to detect the real thing”.

Materials with properties that are engineered by manipulating their structure, rather than their chemical composition, are known as metamaterials. Previously, these have been used to create longer-lived, artificial black holes, which might be used to harvest solar energy, as well as invisibility cloaks.

Reference: