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Black glass holds first Mars soil sample on Earth
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tim fitzharris/flpa
THE Chinese soft-shelled turtle’s mild-mannered nature hides a potty mouth like no other. The reptile may be the only animal to urinate through its oral cavity. The turtle (Pelodiscus sinensis) has a mouth lined with tiny protrusions that boost the surface area for gas exchange, allowing the animal to breathe underwater. Alex Yuen Kwong Ip of the National University of Singapore thinks the protrusions serve an additional purpose. His team kept four turtles in tanks of water. Each turtle had a tube attached to its cloaca, where urine would normally exit the body. Ip found that the cloaca accounted for just 6 per cent of the urea – a major component of urine – that turned up in the water. When the turtles were kept on land, with access to buckets of water, they would dunk their heads, fill their mouths with water and then spit it out – at which point the urea level in the water rose. Ip quickly came to certain conclusions. “I know of no other animals that can excrete urea through the mouth,” says Ip. Proteins in the unusual mouth lining actively transport urea out of the bloodstream, he says. The protrusions are also key, helping the turtle’s toilet mouth work efficiently (Journal of Experimental Biology, doi.org/jhh).
Existential blow for ghostly quantum supersolid A GHOSTLY material is facing an existential crisis. One of the physicists who first claimed to have glimpsed a “supersolid” says the original experiment was flawed. Normally the atoms of a solid form a regular lattice, giving them a rigid structure. But quantum theory says this can change: when solids get ultracold, some atoms should pass through the lattice, flowing like a frictionless liquid. In 2004, Moses Chan of Pennsylvania State University and his erstwhile colleague Eunseong
Kim repeatedly spun a chamber containing a chunk of porous glass saturated with helium, first one way, then the other. As they cooled the set-up, the rotation sped up, hinting that less and less helium was travelling with the spinning glass. Instead, it appeared that some helium was standing still inside the glass, a telltale sign of the lack of friction characteristic of a supersolid. Then in 2007 it emerged that a chunk of solid helium, known as “bulk” helium, gets stiffer than expected at low temperatures.
This could explain the faster oscillations without the need to invoke supersolidity. Though bulk helium was not part of the 2004 experiment by design, some may have formed in the gap between the glass and its chamber. Chan has now repeated the experiment, after sealing the glass to rule out the presence of bulk helium. The changes in oscillation rate vanished, suggesting that the changes seen in 2004 were due to the stiffening of bulk helium, not supersolidity after all (Physical Review Letters, doi.org/jhz). Nick Cobbing/Greenpeace/eyevine
Turtle with a foulmouthed habit
Martian soil crashlands on Earth BLACK glass in a meteorite that crashed in the Moroccan desert contains the first confirmed traces of Martian soil brought to Earth. The find represents a rare chance to look closely at ancient surface conditions on Mars. The space rock, called Tissint, was most likely ejected from Mars about 700,000 years ago by an asteroid impact. People witnessed its fall to Earth in 2011 and quickly retrieved the fragments. The rock’s pristine interior is laced with a large amount of bubbly black glass, says Hasnaa Chennaoui Aoudjehane of Hassan II University in Casablanca, Morocco. This glass contains relatively high amounts of light rare-earth elements, some of which seem to have been oxidised (Science, doi.org/jh2). Conditions that would oxidise these elements are most likely to exist close to Mars’s surface. The team says weakly acidic water may have leached rareearth elements from Martian soil and deposited them in fractures in surface rocks. Heat from the asteroid impact that ejected Tissint melted the material in the fractures, which crystallised as it cooled, forming the black glass.
Greenland melt disturbs the Atlantic FRESHER isn’t always better. Cold, fresh water pouring into the Atlantic from Greenland could interfere with currents and even the ocean’s ability to store carbon. Jonathan Bamber of the University of Bristol, UK, and his colleagues have reconstructed the amount of meltwater running off from Greenland’s glaciers (pictured) between 1958 and 2010. The losses have sped up since the early 1990s, with the south-east of the island seeing losses rise by 50 per cent in less than 20 years (Geophysical Research Letters, doi.org/jg6).
The inflow of fresh water will mix with seawater to form a relatively buoyant surface layer that is less likely to sink. This weakens the Atlantic Meridional Overturning Circulation (AMOC), the current that carries tropical water to northern Europe. The weaker AMOC is also less able to replace the surface water once it is saturated with carbon dioxide from the air. “If you slow the AMOC, you’re decreasing the ability of the ocean to take up carbon dioxide,” says Ruth Curry of the Woods Hole Oceanographic Institution in Massachusetts.
20 October 2012 | NewScientist | 15
tim fitzharris/flpa
THE Chinese soft-shelled turtle’s mild-mannered nature hides a potty mouth like no other. The reptile may be the only animal to urinate through its oral cavity. The turtle (Pelodiscus sinensis) has a mouth lined with tiny protrusions that boost the surface area for gas exchange, allowing the animal to breathe underwater. Alex Yuen Kwong Ip of the National University of Singapore thinks the protrusions serve an additional purpose. His team kept four turtles in tanks of water. Each turtle had a tube attached to its cloaca, where urine would normally exit the body. Ip found that the cloaca accounted for just 6 per cent of the urea – a major component of urine – that turned up in the water. When the turtles were kept on land, with access to buckets of water, they would dunk their heads, fill their mouths with water and then spit it out – at which point the urea level in the water rose. Ip quickly came to certain conclusions. “I know of no other animals that can excrete urea through the mouth,” says Ip. Proteins in the unusual mouth lining actively transport urea out of the bloodstream, he says. The protrusions are also key, helping the turtle’s toilet mouth work efficiently (Journal of Experimental Biology, doi.org/jhh).
Existential blow for ghostly quantum supersolid A GHOSTLY material is facing an existential crisis. One of the physicists who first claimed to have glimpsed a “supersolid” says the original experiment was flawed. Normally the atoms of a solid form a regular lattice, giving them a rigid structure. But quantum theory says this can change: when solids get ultracold, some atoms should pass through the lattice, flowing like a frictionless liquid. In 2004, Moses Chan of Pennsylvania State University and his erstwhile colleague Eunseong
Kim repeatedly spun a chamber containing a chunk of porous glass saturated with helium, first one way, then the other. As they cooled the set-up, the rotation sped up, hinting that less and less helium was travelling with the spinning glass. Instead, it appeared that some helium was standing still inside the glass, a telltale sign of the lack of friction characteristic of a supersolid. Then in 2007 it emerged that a chunk of solid helium, known as “bulk” helium, gets stiffer than expected at low temperatures.
This could explain the faster oscillations without the need to invoke supersolidity. Though bulk helium was not part of the 2004 experiment by design, some may have formed in the gap between the glass and its chamber. Chan has now repeated the experiment, after sealing the glass to rule out the presence of bulk helium. The changes in oscillation rate vanished, suggesting that the changes seen in 2004 were due to the stiffening of bulk helium, not supersolidity after all (Physical Review Letters, doi.org/jhz). Nick Cobbing/Greenpeace/eyevine
Turtle with a foulmouthed habit
Martian soil crashlands on Earth BLACK glass in a meteorite that crashed in the Moroccan desert contains the first confirmed traces of Martian soil brought to Earth. The find represents a rare chance to look closely at ancient surface conditions on Mars. The space rock, called Tissint, was most likely ejected from Mars about 700,000 years ago by an asteroid impact. People witnessed its fall to Earth in 2011 and quickly retrieved the fragments. The rock’s pristine interior is laced with a large amount of bubbly black glass, says Hasnaa Chennaoui Aoudjehane of Hassan II University in Casablanca, Morocco. This glass contains relatively high amounts of light rare-earth elements, some of which seem to have been oxidised (Science, doi.org/jh2). Conditions that would oxidise these elements are most likely to exist close to Mars’s surface. The team says weakly acidic water may have leached rareearth elements from Martian soil and deposited them in fractures in surface rocks. Heat from the asteroid impact that ejected Tissint melted the material in the fractures, which crystallised as it cooled, forming the black glass.
Greenland melt disturbs the Atlantic FRESHER isn’t always better. Cold, fresh water pouring into the Atlantic from Greenland could interfere with currents and even the ocean’s ability to store carbon. Jonathan Bamber of the University of Bristol, UK, and his colleagues have reconstructed the amount of meltwater running off from Greenland’s glaciers (pictured) between 1958 and 2010. The losses have sped up since the early 1990s, with the south-east of the island seeing losses rise by 50 per cent in less than 20 years (Geophysical Research Letters, doi.org/jg6).
The inflow of fresh water will mix with seawater to form a relatively buoyant surface layer that is less likely to sink. This weakens the Atlantic Meridional Overturning Circulation (AMOC), the current that carries tropical water to northern Europe. The weaker AMOC is also less able to replace the surface water once it is saturated with carbon dioxide from the air. “If you slow the AMOC, you’re decreasing the ability of the ocean to take up carbon dioxide,” says Ruth Curry of the Woods Hole Oceanographic Institution in Massachusetts.
20 October 2012 | NewScientist | 15