February 20, 2007, 8:45 PM CT

Formation of auroras

Giant electrical circuits power the magical open-air light show of the auroras, forming arcs in high-latitude regions like Scandinavia. New results obtained thanks to ESA's Cluster satellites provide a new insight into the source of the difference between the two types of electrical circuits currently known to be associated to the auroral arcs.

The deep mechanisms that rule the creation of the beautiful auroras, or polar lights, have been the subject of studies that are keeping solar and plasma scientists busy since years. While early rockets and ground-observations have already provided a few important clues for the understanding of these phenomena, the real break-throughs in our knowledge have started with dedicated auroral satellites, such as S3-3, Dynamics Explorer, Viking, Freja and FAST, and have now come to full fruition with ESA's multi-point mission Cluster.

The basic process generating auroras is similar to what happens in an old TV tube. In the TV tube, accelerated electrons hit the screen and make its phosphore glow; electrons in the atmosphere get accelerated in an 'acceleration region' situated between about 5000 and 8000 kilometres altitude, and rush down to the Earth's ionosphere - a region of the upper atmosphere. Here, they crash into ionospheric atoms and molecules, transfer to them some of their energy and so cause them to glow, creating aurorae......... Posted by: Sean      Read more         Source

February 20, 2007, 8:38 PM CT

Universe contains more calcium than expected

The universe contains one and a half times more calcium than previously assumed. This conclusion was drawn by astronomers of the SRON Netherlands Institute for Space Research, after observations with ESA's XMM-Newton X-ray observatory.

This research offers researchers new insights in the formation history of the elemental building blocks of the cosmos in which supernovae play a crucial role.

The iron in our blood, the oxygen we breathe, the calcium in our bones, the silicon in the sand box, all the atoms we are made of are released during the violent final moments of massive stars in the act of dying. These so-called supernova explosions eject newly made chemical elements into space where they become the building blocks for new stars, planets, or even life. However, a number of questions concerning the very formation of elements and the way they get distributed across the universe still remain open.

As per Jelle de Plaa, space researcher at SRON, a number of answers can be found in distant clusters of galaxies. "Clusters are in a number of ways the big cities of the universe", he says.

"They consist of hundreds of galaxies, each containing thousands of millions of stars. The galaxies are embedded in a gigantic cloud of hot gas that fills this cluster like a smog. Due to their enormous size and numbers, clusters contain a large fraction of the total amount of matter in the universe. During the past thousand-millions of years supernova explosions have enriched the surrounding hot gas with heavier elements, like oxygen, silicon and iron."........ Posted by: Sean      Read more         Source

February 19, 2007, 8:25 PM CT

All Set For Mars Swing-by

UK researchers from 10 institutions are involved in the instruments on both the Rosetta orbiter and lander some of which will be operating during the flyby. UK industry is also heavily involved in the mission, having provided key components, including the mission control system (SciSys UK Ltd) and the orbit control and propulsion system (EADS Astrium, UK). SciSys staff will be closely monitoring events at ESA's European Space Operations Centre (ESOC) in Gera number of where the manoeuvre is being co-ordinated.

Launched in March 2004 the three tonne spacecraft could not be sent on its correct trajectory by the launcher and so on its journey it will make a series of planned gravity assist manoeuvres past the Earth and Mars.

Professor Keith Mason, Chief Executive of PPARC said, "With Rosetta now 3 years into its epic 10 year journey this flyby is an important milestone for the spacecraft. Not only will it help set it on its correct path but it provides a further opportunity to find out more about Mars from a different perspective".

Rosetta's closest approach to Mars will be made at 0153 GMT on 25th February 2007, 1090 days since launch.The distance from Rosetta to the surface of Mars will be around 250 km, and at its closest approach the spacecraft will be travelling at around 10.1 km/s (~36,400 kph ~22,700 mph) relative to the centre of Mars......... Posted by: Sean      Read more         Source

February 13, 2007, 9:29 PM CT

The colourful demise of a Sun-like star

A brand new image taken with Hubble's Wide Field Planetary Camera 2 shows the planetary nebula NGC 2440 - the chaotic structure of the demise of a star.

This image, just taken by the NASA/ESA Hubble Space Telescope, shows the colourful "last hurrah" of a star like our Sun. The star is ending its life by casting off its outer layers of gas, which formed a cocoon around the star's remaining core. Ultraviolet light from the dying star makes the material glow. The burned-out star, called a white dwarf, is the white dot in the centre. Our Sun will eventually burn out and shroud itself with stellar debris, but not for another 5 billion years.

Our Milky Way Galaxy is littered with these stellar relics, called planetary nebulae. The objects have nothing to do with planets. Eighteenth- and nineteenth-century astronomers called them the name because through small telescopes they resembled the disks of the distant planets Uranus and Neptune. The planetary nebula in this image is called NGC 2440. The white dwarf at the centre of NGC 2440 is one of the hottest known, with a surface temperature of more than 200,000 degrees Celsius. The nebula's chaotic structure suggests that the star shed its mass episodically. During each outburst, the star expelled material in a different direction. This can be seen in the two bowtie-shaped lobes. The nebula also is rich in clouds of dust, some of which form long, dark streaks pointing away from the star. NGC 2440 lies about 4,000 light-years from Earth in the direction of the constellation Puppis......... Posted by: Sean      Read more         Source

February 12, 2007, 8:50 PM CT

Rocket Launches From Poker Flat

This morning, a NASA suborbital sounding rocket launched from Poker Flat Research Range into an aurora display over northern Alaska at 3:45 a.m. Alaska Standard Time, allowing scientists to gather more data about the power source behind pulsating auroras.

Marc Lessard of the physics department at the University of New Hampshire was the principle investigator for the experiment to investigate various aspects of pulsating aurora. The 662 pound experiment housed in the nose cone of a 65-foot Black Brant XII rocket arced above the atmosphere 408 miles above northern Alaska. Pulsating aurora is a subtle type of aurora that seems to blink on and off in large round patches.

Lessard's experiment, called ROPA (Rocket Observations of Pulsating Aurora), was complex even by rocket-science standards. It had a main instrument cluster, known as a payload, and three sub-payloads, which separated early after the rocket cleared the upper atmosphere at an altitude of 140 miles. Two of the sub-payloads had their own rocket motors, propelling them away from the main payload where they obtained measurements of the pulsating aurora, which occurred near the latitude of Toolik Lake on Alaska's North Slope. Dirk Lummerzheim of the University of Alaska Fairbanks' Geophysical Institute was on the ground at Toolik Lake. During the launch, he identified what looked like pulsating aurora in the all-sky camera at the research station there......... Posted by: Sean      Read more         Source

February 8, 2007, 9:53 PM CT

Closest Gravitational Lensing Galaxy

A giant elliptical galaxy seen in an image from the Hubble Space Telescope is the closest gravitational lens yet known, as per information released by the Hubble Heritage Project.

John Blakeslee, an assistant professor with the Department of Physics and Astronomy at Washington State University, working with colleagues from the University of Hawaii and the University of Durham in England, targeted the galaxy for a closer look by Hubble.

"The galaxy was well-known, but the Hubble images reveal so much more detail about it, including the unexpected finding that it's the nearest gravitational lens," said Blakeslee.

A gravitational lens is a celestial object so huge that it has enough mass to deflect, magnify and focus light emitted by an object that is on the opposite side of it from Earth. The result is that when viewed from Earth, the more distant object appears as an arc or ring rather than a spot or spiral. Such images are known as "Einstein rings" because Albert Einstein first predicted them.

Despite the huge number of galaxies in the universe, said Blakeslee, "gravitational lensing is a rare occurrence because it requires an almost perfect alignment of a distant galaxy with an intervening one that has enough mass to gravitationally focus the light."........

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February 8, 2007, 8:46 PM CT

Enceladus is a 'cosmic graffiti artist'

Astronomers from the University of Virginia and other institutions have observed that Enceladus, the sixth-largest moon of Saturn, is a "cosmic graffiti artist," pelting the surfaces of at least 11 other moons of Saturn with ice particles sprayed from its spewing surface geysers. This ice sandblasts the other moons, creating a reflective surface that makes them among the brightest bodies in the solar system (Enceladus, itself a ball of mostly ice, is the single most reflective body in our solar system).

"Enceladus' art is a work-in-progress, constantly altering the surfaces of other moons orbiting within this moon's beautiful swirl of ice particles," said Anne Verbiscer, a research scientist in the astronomy department at the University of Virginia and the study's lead investigator. "We've dubbed Enceladus a graffiti artist because of its ability to alter the appearance of the other moons".

A paper about her and her colleagues' findings appears in the Feb. 9 issue of the journal Science.

The ring of ice particles Enceladus forms around Saturn is known as the E-ring. At least 11 other moons orbit within the E-ring and are constantly subjected to high velocity collisions with Enceladus's icy wake.

A series of geysers at Enceladus's south pole continually erupt, ejecting ice particles, spewing a swirling wispy trail in the moon's wake and ultimately forming a cloudy ring of ice particles. The ring is added to over and over as Enceladus repeats its orbit. The particles may persist for thousands of years, until they collide with one of the embedded moons, including Enceladus as it flows through its own emissions.........

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February 5, 2007, 8:48 PM CT

Our tempest not even breeze here

Earth's inhabitants are used to temperatures that vary, sometimes greatly, between day and night. New measurements for three planets outside our solar system indicate their temperatures remain fairly constant -- and blazing hot -- from day to night, even though it is likely one side of each planet always faces its sun and the other is in permanent darkness.

The reason apparently is supersonic winds, perhaps as strong as 9,000 miles an hour, that constantly churn the planets' atmospheres and keep temperatures on the dark side from plunging.

The planets, gas giants similar in size to Jupiter, were discovered in the last decade orbiting stars about the same size as our sun and less than 150 light years from Earth. All of them orbit within about 5 million miles of their stars, far less than Mercury's distance from our sun.

Astronomers have wondered whether planets orbiting so close to their stars but with one side in constant daylight and the other permanently dark would exhibit sharp temperature differences between the day side and the night side. For the three planets in this study, the temperatures appear to be constant, likely because of the strong winds that mix the atmosphere planetwide, said Eric Agol, a University of Washington assistant professor of astronomy and co-author of a poster presenting the findings today at the American Astronomical Society national meeting in Seattle.........

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February 4, 2007, 8:18 PM CT

mammoth cloud engulfing Titan's North Pole

A giant cloud half the size of the United States has been imaged on Saturn's moon Titan by the Cassini spacecraft. The cloud may be responsible for the material that fills the lakes discovered last year by Cassini's radar instrument.

Cloaked by winter's shadow, this cloud has now come into view as winter turns to spring. The cloud extends down to 60 degrees north latitude, is roughly 2400 kilometers in diameter and engulfs almost the entire north pole of Titan.

The new image was acquired on 29 December 2006, by Cassini's visual and infrared mapping spectrometer (VIMS). Scientific models predicted this cloud system but it had never been imaged with such details before.

"We knew this cloud had to be there but were amazed at its size and structure," said Dr. Christophe Sotin of the University of Nantes, France, a member of the visual and infrared mapping spectrometer team and distinguished visiting scientist at NASA's Jet Propulsion Laboratory, Pasadena, California. "This cloud system may be a key element in the global formation of organics and their interaction with the surface."

The same cloud system seen on 29 December 2006, was still there two weeks later during the flyby which took place on 13 January 2007, even though observing conditions were slightly less favorable than in December.........

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January 30, 2007, 4:36 AM CT

Dig Deeper To Find Martian Life

Probes designed to find life on Mars do not drill deep enough to find the living cells that researchers believe may exist well below the surface of Mars, as per research led by UCL (University College London). Eventhough current drills may find essential tell-tale signs that life once existed on Mars, cellular life could not survive the radiation levels for long enough any closer to the surface of Mars than a few metres deep - beyond the reach of even state-of-the-art drills.

The study, reported in the journal 'Geophysical Research Letters' (GRL), maps out the cosmic radiation levels at various depths, taking into account different surface conditions on Mars, and shows that the best place to look for living cells is within the ice at Elysium, the location of the newly discovered frozen sea on Mars.

The lead author, Lewis Dartnell, UCL Centre for Mathematics and Physics in the Life Sciences & Experimental Biology (CoMPLEX), said: "Finding hints that life once existed - proteins, DNA fragments or fossils - would be a major discovery in itself, but the Holy Grail for astrobiologists is finding a living cell that we can warm up, feed nutrients and reawaken for studying.

"It just isn't plausible that dormant life is still surviving in the near-subsurface of Mars - within the first couple of metres below the surface - in the face of the ionizing radiation field. Finding life on Mars depends on liquid water surfacing on Mars, but the last time liquid water was widespread on Mars was billions of years ago. Even the hardiest cells we know of could not possibly survive the cosmic radiation levels near the surface of Mars for that long".........

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