Spacecraft controllers have just awoken Rosetta from hibernation to prepare for its encounter with asteroid (2867) Steins on 5 September. ESA's comet chaser will study the relatively rare asteroid as it flies by on its way to comet 67/P Churyumov-Gerasimenko.
Launched in March 2004, Rosetta will reach its final destination only in 2014, after travelling a total of about 6500 million km. The distance between the spacecraft and the Sun as it approaches the comet will be about 600 million or 4 AU (1 AU or 1 Astronomical Unit is equal to 150 million km, the mean distance between Earth and the Sun).
Rosetta has swung by Earth twice and Mars once, performing gravity-assist manoeuvres, that gave it the necessary boost to continue on its journey. The third and last Earth swing-by is scheduled for November 2009. The spacecraft will also fly by two asteroids and study them on the way: (2867) Steins in September this year and (21) Lutetia in June 2010. As it closes in on (2867) Steins in September, Rosetta will have travelled about 3700 million km and will be 2.1 AU from the Sun.
Science & Technology
A Baby Is Born With A Head On Her Shoulders And A Mind Primed For Learning. But It Takes Years Of Experience--Looking, Listening, Playing, Interacting With Parents--To Wire The Billions Of Complex Neural Circuits That Govern Language, Math, Music, Logic And Emotions.
WASHINGTON - The solar system may not be a nice round shape, but rather a bit squashed and oblong, according to data from the Voyager 2 spacecraft exploring the solar system's outer limits, scientists said on Wednesday.
Launched in 1977, the Voyager 1 and Voyager 2 unmanned probes are now studying the edges of the heliosphere, the huge magnetic "bubble" around our solar system created by the solar wind as it runs up against the thin gas in interstellar space.
The solar wind is made up of electrically charged particles blown into space in all directions by the sun. The boundary between the heliosphere and the rest of interstellar space is known as the "termination shock."
Voyager 2 in August 2007 crossed this boundary 7.8 billion miles from the sun.
Voyager 1 had crossed the boundary in December 2004 about 10 billion miles away from Voyager 1 and almost a billion miles farther from the sun.
Scientists think this indicates that the bubble carved into interstellar space by the heliosphere, which extends well past the distant orbit of Pluto, is not perfectly round, and the solar system is shaped a bit like an oblong.
Launched in 1977, the Voyager 1 and Voyager 2 unmanned probes are now studying the edges of the heliosphere, the huge magnetic "bubble" around our solar system created by the solar wind as it runs up against the thin gas in interstellar space.
The solar wind is made up of electrically charged particles blown into space in all directions by the sun. The boundary between the heliosphere and the rest of interstellar space is known as the "termination shock."
Voyager 2 in August 2007 crossed this boundary 7.8 billion miles from the sun.
Voyager 1 had crossed the boundary in December 2004 about 10 billion miles away from Voyager 1 and almost a billion miles farther from the sun.
Scientists think this indicates that the bubble carved into interstellar space by the heliosphere, which extends well past the distant orbit of Pluto, is not perfectly round, and the solar system is shaped a bit like an oblong.
Thanks to salt and hot chili peppers, researchers have found a calculus-computing center that tells a roundworm to go forward toward dinner or turn to broaden the search. It's a computational mechanism, they say, that is similar to what drives hungry college students to a pizza.
These behavior-driving calculations, according to a paper published in the July 3 issue of the journal Nature, are done "in a tiny, specialized computer inside a primitive roundworm," says principal investigator Shawn Lockery, a University of Oregon biologist and member of the UO Institute of Neuroscience.
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| ©Shawn Lockery |
| A spike in salt concentration in ASEL (left neuron) activates expression that leads a worm to proceed in a straight line. A dip in salt levels in ASER (right neuron) turns on a negative reaction that tells a worm to change to a turning movement to look around. |
These behavior-driving calculations, according to a paper published in the July 3 issue of the journal Nature, are done "in a tiny, specialized computer inside a primitive roundworm," says principal investigator Shawn Lockery, a University of Oregon biologist and member of the UO Institute of Neuroscience.
Geological evidence found in Ohio and Indiana in recent weeks is strengthening the case to attribute what happened 12,900 years ago in North America -- when the end of the last Ice Age unexpectedly turned into a phase of extinction for animals and humans - to a cataclysmic comet or asteroid explosion over top of Canada.
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| ©University of Cincinnati |
| Ken Tankersley |
A complete mandible of Homo erectus was discovered at the Thomas I quarry in Casablanca by a French-Moroccan team co-led by Jean-Paul Raynal, CNRS senior researcher at the PACEA laboratory (CNRS/Université Bordeaux 1/ Ministry of Culture and Communication). This mandible is the oldest human fossil uncovered from scientific excavations in Morocco. The discovery will help better define northern Africa's possible role in first populating southern Europe.
A Homo erectus half-jaw had already been found at the Thomas I quarry in 1969, but it was a chance discovery and therefore with no archeological context. This is not the case for the fossil discovered May 15, 2008, whose characteristics are very similar to those of the half-jaw found in 1969.
The morphology of these remains is different from the three mandibles found at the Tighenif site in Algeria that were used, in 1963, to define the North African variety of Homo erectus, known as Homo mauritanicus, dated to 700,000 B.C.
A Homo erectus half-jaw had already been found at the Thomas I quarry in 1969, but it was a chance discovery and therefore with no archeological context. This is not the case for the fossil discovered May 15, 2008, whose characteristics are very similar to those of the half-jaw found in 1969.
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| ©Jean-Paul Raynal |
| Photograph of the fossil human mandible discovered May 15, 2008 at the Thomas I quarry site in Casablanca. |
The morphology of these remains is different from the three mandibles found at the Tighenif site in Algeria that were used, in 1963, to define the North African variety of Homo erectus, known as Homo mauritanicus, dated to 700,000 B.C.
Collisions have consequences. Everyone knows that. Whether it's between trains, planes, automobiles or atoms, there are always repercussions. But while macroscale collisions may have the most obvious effects - mangled steel, bruised flesh - sometimes it is the tiniest collisions that have the most resounding repercussions.
Such may be the case with the results of new experimental research on collisions between a single hydrogen atom and a lone molecule of deuterium - the smallest atom and one of the smallest molecules, respectively - conducted by a team led by Richard Zare, a professor of chemistry at Stanford University.
When an atom collides with a molecule, traditional wisdom said the atom had to strike one end of the molecule hard to deliver energy to it. People thought a glancing blow from an atom would be useless in terms of energy transfer, but that turns out not to be the case, according to the researchers.
Such may be the case with the results of new experimental research on collisions between a single hydrogen atom and a lone molecule of deuterium - the smallest atom and one of the smallest molecules, respectively - conducted by a team led by Richard Zare, a professor of chemistry at Stanford University.
When an atom collides with a molecule, traditional wisdom said the atom had to strike one end of the molecule hard to deliver energy to it. People thought a glancing blow from an atom would be useless in terms of energy transfer, but that turns out not to be the case, according to the researchers.
A University of Chicago expedition at Tell Edfu in southern Egypt has unearthed a large administration building and silos that provide fresh clues about the emergence of urban life. The discovery provides new information about a little understood aspect of ancient Egypt - the development of cities in a culture that is largely famous for its monumental architecture.
The archaeological work at Tell Edfu was initiated with the permission of the Supreme Council of Antiquities, headed by Zahi Hawass, under the direction of Nadine Moeller, Assistant Professor at the Oriental Institute, University of Chicago. Work late last year revealed details of seven silos, the largest grain bins found in ancient Egypt as well as an older columned hall that was an administration center.
Long fascinated with temples and monuments such as pyramids, scholars have traditionally spent little time exploring the residential communities of ancient Egypt. Due to intense farming and heavy settlement over the years, much of the record of urban civilization has been lost. So little archaeological evidence remains that some scholars believe Egypt did not have a highly developed urban culture, giving Mesopotamia the distinction of teaching people how to live in cities.
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| ©N. Moeller, Tell Edfu Project |
| Excavation area at Tell Edfu showing superimposed settlement layers dating to various phases, with some of the silos of the 17th Dynasty (ca. 1650-1520 BC) covered by a thick ash layer on top into which several storage compartments were built which are of a later date. |
The archaeological work at Tell Edfu was initiated with the permission of the Supreme Council of Antiquities, headed by Zahi Hawass, under the direction of Nadine Moeller, Assistant Professor at the Oriental Institute, University of Chicago. Work late last year revealed details of seven silos, the largest grain bins found in ancient Egypt as well as an older columned hall that was an administration center.
Long fascinated with temples and monuments such as pyramids, scholars have traditionally spent little time exploring the residential communities of ancient Egypt. Due to intense farming and heavy settlement over the years, much of the record of urban civilization has been lost. So little archaeological evidence remains that some scholars believe Egypt did not have a highly developed urban culture, giving Mesopotamia the distinction of teaching people how to live in cities.
A delicate ribbon of gas floats eerily in our galaxy. A contrail from an alien spaceship? A jet from a black-hole? Actually this image, taken by NASA's Hubble Space Telescope, is a very thin section of a supernova remnant caused by a stellar explosion that occurred more than 1,000 years ago.
On or around May 1, 1006 A.D., observers from Africa to Europe to the Far East witnessed and recorded the arrival of light from what is now called SN 1006, a tremendous supernova explosion caused by the final death throes of a white dwarf star nearly 7,000 light-years away. The supernova was probably the brightest star ever seen by humans, and surpassed Venus as the brightest object in the night time sky, only to be surpassed by the moon. It was visible even during the day for weeks, and remained visible to the naked eye for at least two and a half years before fading away.
It wasn't until the mid-1960s that radio astronomers first detected a nearly circular ring of material at the recorded position of the supernova. The ring was almost 30 arcminutes across, the same angular diameter as the full moon. The size of the remnant implied that the blast wave from the supernova had expanded at nearly 20 million miles per hour over the nearly 1,000 years since the explosion occurred.
On or around May 1, 1006 A.D., observers from Africa to Europe to the Far East witnessed and recorded the arrival of light from what is now called SN 1006, a tremendous supernova explosion caused by the final death throes of a white dwarf star nearly 7,000 light-years away. The supernova was probably the brightest star ever seen by humans, and surpassed Venus as the brightest object in the night time sky, only to be surpassed by the moon. It was visible even during the day for weeks, and remained visible to the naked eye for at least two and a half years before fading away.
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| ©NASA, ESA, and the Hubble Heritage Team (STScI/AURA) |
| A delicate ribbon of gas floats eerily in our galaxy. A contrail from an alien spaceship? A jet from a black-hole? Actually this image, taken by NASA's Hubble Space Telescope, is a very thin section of a supernova remnant caused by a stellar explosion that occurred more than 1,000 years ago. |
It wasn't until the mid-1960s that radio astronomers first detected a nearly circular ring of material at the recorded position of the supernova. The ring was almost 30 arcminutes across, the same angular diameter as the full moon. The size of the remnant implied that the blast wave from the supernova had expanded at nearly 20 million miles per hour over the nearly 1,000 years since the explosion occurred.
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| ©Josep Renalias/Wikipedia |
British scientists have solved an important mystery; how traces of the element mercury with volcanic signatures ends up in polar ice cores far away from any volcanoes.
"It has always been a mystery how trace metals, like mercury, with a volcanic signature find their way into polar ice in regions without nearby evidence of volcanic activity," said Dr David Pyle of Oxford University's Department of Earth Sciences who led the research team with colleague Dr Tamsin Mather. "These traces only appear as a faint 'background signal' in ice cores but up until now it has still been difficult to explain."
