A Nasa spacecraft has detected oxygen around one of Saturn's icy moons, Dione.
The discovery supports a theory that suggests all of the moons near Saturn and Jupiter might have oxygen around them.
Researchers say that their finding increases the likelihood of finding the ingredients for life on one of the moons orbiting gas giants.
The study has been published in Geophysical Research Letters.
According to co-author Andrew Coates of University College London, Dione has no liquid water and so does not have the conditions to support life. But it is possible that other moons of Jupiter and Saturn do.
"Some of the other moons have liquid oceans and so it is worth looking more closely at them for signs of life," Prof Coates said.
The discovery was made using the Cassini spacecraft, which flew by Dione nearly two years ago. Instruments on board the unmanned probe detected a thin layer of oxygen around the moon, so thin that scientists prefer to call it an "exosphere" rather than an atmosphere.
But the discovery is important because it suggests there is a process at work around the solar system's gas giants, Saturn and Jupiter, in which oxygen is released from their icy satellites.
It seems that highly charged particles from the planets' powerful radiation belts split the water in the ice into hydrogen and oxygen.
Dione's sister moon, Enceladus is thought to harbour a liquid ocean below its icy surface. The same is thought to be true of Europa, Callisto and Ganymede which orbit Jupiter.
Prof Coates is among a group of scientists lobbying the European Space Agency to send an orbiter to explore Jupiter's icy moons - known as the Juice mission.
"These are fascinating places to look for signs of life," he said.
As is Titan, Saturn's largest satellite. Its nitrogen and methane atmosphere is reminiscent of the early Earth, according to Prof Coates.
"It may be an Earth waiting to happen as the outer Solar System warms up," he said.
Nasa is developing a proposal to send a landing craft, or lander, to float on one of the planet's oily lakes.
Monday, March 05, 2012
Dinosaurs had fleas too _ giant ones, fossils show
Handout photo released by the Nature magazine and obtained on Feburary 28, 2012 shows a female flea from the early Cretaceous period. The giant dinosaurs that roamed the world some 150 million years ago shared the planet with equally daunting parasites: blood-gobbling fleas that were up two centimetres (almost an inch) long. –AFP PHOTO / Nature / D. Huang
WASHINGTON: In the Jurassic era, even the flea was a beast, compared to its minuscule modern descendants. These pesky bloodsuckers were nearly an inch (25 millimeters) long.
New fossils found in China are evidence of the oldest fleas _ from 125 million to 165 million years ago, said Diying Huang of the Nanjing Institute of Geology and Paleontology. Their disproportionately long proboscis, or straw-like mouth, had sharp weapon-like serrated edges that helped them bite and feed from their super-sized hosts, he and other researchers reported Wednesday in the journal Nature.
Scientists figure about eight or more of today’s fleas would fit on the burly back of their ancient ancestor.
‘‘That’s a beast,’’ said study co-author Michael Engel, entomology curator at the Natural History Museum at the University of Kansas. ‘‘It was a big critter. I can’t even imagine coming home and finding my miniature schnauzer with one or more of these things crawling around on it.’’
The ancient female fleas were close to twice the size of the males, researchers found, which fits with modern fleas.
Engel said it is not just the size, however, that was impressive about the nine flea fossils. It was their fearsome beak capable of sticking into and sucking blood from the hides of certain dinosaurs, probably those that had feathers.
These flea beaks ‘‘had almost like a saw running down the side,’’ Engel said. ‘‘This thing was packing a weapon. They were equipped to dig into something.’’
While the ancient fleas were big, they had one disadvantage compared to modern ones: Their legs were not well developed. Evolving over time, fleas went from crawling to jumping, Huang said.
‘‘Luckily for the land animals of the Mesozoic, these big flat fleas lacked the tremendous jumping capacity that our common fleas have,’’ said Joe Hannibal of the Cleveland Museum of Natural History. He was not involved in the study, but he praised it as useful and interesting.
Just finding the fleas was a stroke of luck, Huang said. He first found one in a Chinese fossil market and mentioned it to someone at his hotel. The other guest showed him a photo of another fossilized flea, telling him it was from Daohugou in northeastern China, where there is a famous fossil bed from about 165 million years ago. Huang went there and found fleas preserved in a brownish film of volcanic ash. The grains of rock were so fine you could see antennae and other details of the fleas, he said.
Modern fleas get engorged after they feast on blood, but these did not seem engorged, Engel said.
It should not seem very surprising that large fleas existed more than 100 million years ago. If you go back even farther in time, ancestors of dragonflies and damsel flies had 3-foot-long (1 meter-long) wingspans, Engel said.
WASHINGTON: In the Jurassic era, even the flea was a beast, compared to its minuscule modern descendants. These pesky bloodsuckers were nearly an inch (25 millimeters) long.
New fossils found in China are evidence of the oldest fleas _ from 125 million to 165 million years ago, said Diying Huang of the Nanjing Institute of Geology and Paleontology. Their disproportionately long proboscis, or straw-like mouth, had sharp weapon-like serrated edges that helped them bite and feed from their super-sized hosts, he and other researchers reported Wednesday in the journal Nature.
Scientists figure about eight or more of today’s fleas would fit on the burly back of their ancient ancestor.
‘‘That’s a beast,’’ said study co-author Michael Engel, entomology curator at the Natural History Museum at the University of Kansas. ‘‘It was a big critter. I can’t even imagine coming home and finding my miniature schnauzer with one or more of these things crawling around on it.’’
The ancient female fleas were close to twice the size of the males, researchers found, which fits with modern fleas.
Engel said it is not just the size, however, that was impressive about the nine flea fossils. It was their fearsome beak capable of sticking into and sucking blood from the hides of certain dinosaurs, probably those that had feathers.
These flea beaks ‘‘had almost like a saw running down the side,’’ Engel said. ‘‘This thing was packing a weapon. They were equipped to dig into something.’’
While the ancient fleas were big, they had one disadvantage compared to modern ones: Their legs were not well developed. Evolving over time, fleas went from crawling to jumping, Huang said.
‘‘Luckily for the land animals of the Mesozoic, these big flat fleas lacked the tremendous jumping capacity that our common fleas have,’’ said Joe Hannibal of the Cleveland Museum of Natural History. He was not involved in the study, but he praised it as useful and interesting.
Just finding the fleas was a stroke of luck, Huang said. He first found one in a Chinese fossil market and mentioned it to someone at his hotel. The other guest showed him a photo of another fossilized flea, telling him it was from Daohugou in northeastern China, where there is a famous fossil bed from about 165 million years ago. Huang went there and found fleas preserved in a brownish film of volcanic ash. The grains of rock were so fine you could see antennae and other details of the fleas, he said.
Modern fleas get engorged after they feast on blood, but these did not seem engorged, Engel said.
It should not seem very surprising that large fleas existed more than 100 million years ago. If you go back even farther in time, ancestors of dragonflies and damsel flies had 3-foot-long (1 meter-long) wingspans, Engel said.
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