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October 16, 2006, 9:30 PM CT

New Details of Mars, Young and Old

New Details of Mars, Young and Old Diverse materials and morphologies in the region south of Mawrth Vallis on Mars
During its first week of observations from low orbit, NASA's newest Mars spacecraft is already revealing new clues about both recent and ancient environments on the red planet.

Scientists hope the Mars Reconnaissance Orbiter will answer questions about the history and distribution of Mars' water by combining data from the orbiter's high-resolution camera, imaging spectrometer, context camera, ground-penetrating radar, atmospheric sounder, global color camera, radio and accelerometers.

Between Sept. 29 and Oct. 6, science instruments on the spacecraft viewed dozens of sites that reflect different episodes in Mars' history. The diverse sites provide a good test for the capabilities of the spacecraft instruments. The orbiter will begin its primary science mission phase in early November when Mars re-emerges from passing nearly behind the sun.

The instruments are seeing details in the shapes and icy composition of geologically young layering near the Martian north pole. Other views offer details of a mid-latitude valley whose upper layers have been eroded away, revealing an underlying clay layer that formed a few billion years ago, when wet conditions produced the clay. Observations of a southern-hemisphere crater show fine-scale details of more recent gullies, adding evidence that they were carved by flowing water.........

Posted by: Edwin      Permalink         Source


October 15, 2006, 8:41 PM CT

Complex Meteorology At Venus

Complex Meteorology At Venus

In its relentless probing of Venus's atmosphere, ESA's Venus Express keeps revealing new details of the Venusian cloud system. Meteorology at Venus is a complex matter, researchers say.

New night-side infrared images gathered by the Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) in July 2006, clearly show new details of a complex cloud system.

The first (false colour) view - the composite of three infrared images acquired by VIRTIS, was taken on 22 July when the spacecraft was flying around the apocentre of its orbit (point of maximum distance from the planet surface) at about 65 000 kilometres altitude. Venus was in the night side.

Using its capability to observe at 1.7-micrometre wavelenght, VIRTIS could probe at about 15-20 kilometres altitude, below the thick cloud deck situated at about 60 kilometres from the surface. The thermal radiation coming from the oven-hot surface of Venus is represented by the intensity of the colours: the brighter the colour (towards white), the more radiation comes from the surface, so the less cloudy the region in the line of sight between the view and the spacecraft is.

The edge of the images, taken at a time interval of about 30 minutes from each other, do not precisely match. This is due to the fact that clouds on Venus move very rapidly and constantly vary their shape. Venus's atmosphere is certainly the most dynamic among the terrestrial planets that have one, taking only four days to completely rotate around the planet.........

Posted by: Edwin      Permalink         Source


October 12, 2006, 8:16 PM CT

Closer to the Edge of a Black Hole

Closer to the Edge of a Black Hole
NASA scientists and their international partners using the new Japanese Suzaku satellite have collected a startling new set of black hole observations, revealing details of twisted space and warped time never before seen with such precision.

The observations include clocking the speed of a black hole's spin rate and measuring the angle at which matter pours into the void, as well as evidence for a wall of X-ray light pulled back and flattened by gravity.

The findings rely on a special feature in the light emitted close to the black hole, called the "broad iron K line," once doubted by some scientists because of poor resolution in earlier observations, now unambiguously revealed as a true measure of a black hole's crushing gravitational force. This technique can be exploited in future X-ray missions.

"Across the board, we are finding the broad iron K line to be an incredibly robust measure of black hole properties," said Andrew Fabian of Cambridge University, England, who led one of the teams. "We are entering the era of precision black hole measurements".

Fabian is the team leader on Suzaku's black hole spin and light-bending observations. James Reeves of NASA's Goddard Space Flight Center, Greenbelt, Md., and Johns Hopkins University, Baltimore, led a second team that observed the first accurate measurement of the angle of a disk of material swirling around a black hole.........

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October 12, 2006, 8:10 PM CT

Headcount Of Local Black Holes

Headcount Of Local Black Holes
NASA researchers using the Swift satellite have conducted the first complete census of galaxies with active, central black holes, a project that scanned the entire sky several times over a nine-month period.

The all-sky survey contains more than 200 supermassive black holes called Active Galactic Nuclei, or AGN, and provides a definitive census of black hole activity in the local universe. The team uncovered a number of new black holes that were previously missed, even in well-studied galaxies, and other surprises as well.

"We are confident that we are seeing every active, supermassive black hole within 400 million light years of Earth," said Jack Tueller of NASA's Goddard Space Flight Center, Greenbelt, Md., who led the effort. "With each passing month, we are able to probe deeper into the universe, and the census becomes richer."

AGN have a mass of millions to billions of suns, which are confined within a region about the size of our solar system. The term "active" refers to the process of actively pulling in gas and whole stars and generating copious amounts of energy from a tiny galactic core in the process. Examples include quasars and Seyfert galaxies.

Swift was built primarily to study gamma-ray bursts. During waiting times between bursts, Swift's Burst Alert Telescope, which is sensitive to the highest-energy X-rays, scans the sky. AGN generate X-rays as well as a number of other forms of light. A number of AGN, however, are hidden behind dust and gas, which block lower-energy light, such as visible light. Because higher-energy X-rays are so penetrating, Swift can detect AGN missed by other surveys, allowing for an unbiased count.........

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October 12, 2006, 8:00 PM CT

Secrets Of Black Hole Jets

Secrets Of Black Hole Jets

NASA and Italian scientists using Swift have for the first time determined what the particle jets streaming from black holes are made of.

Black hole particle jets are commonly seen in quasars and other celestial objects, shooting off at nearly light speed. According to the Swift team, these jets appear to be made of protons and electrons, solving a mystery as old as the discovery of jets themselves in the 1970s. The jets observed by Swift contain about the mass of Jupiter if it were pulverized and blasted out into intergalactic space.

Black hole particle jets typically escape the confines of their host galaxies and flow for hundreds of thousands of light years. They are a primary means of redistributing matter and energy in the universe. They are a key to understanding galaxy formation and are tied to numerous cosmic mysteries, such as the origin of ultrahigh-energy cosmic rays.

"Black hole jets are one of the great paradoxes in astronomy," said Rita Sambruna of NASA's Goddard Space Flight Center, Greenbelt, Md. "How is it that black holes, so efficient at pulling matter in, can also accelerate matter away at near light speed? We still don't know how these jets form, but at least we now have a solid idea about what they're made of".

The composition of black hole jets has been the topic of heated debate for several decades. Scientists generally agree that the jets must be made either of electrons and their antimatter partners, called positrons, or an even mix of electrons and protons. Recent theoretical and observational advances have pointed in the direction of the latter. The Swift data provides the most compelling evidence to date that the jets must have protons.........

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October 12, 2006, 4:59 AM CT

Cassini Finds More Rings

Cassini Finds More Rings
Images taken by NASA's Cassini spacecraft, looking in the direction of the Sun, have provided researchers fresh insights into the dynamic nature of the rings and, in particular, the creation of new rings made from tiny particles released from larger bodies.

Cassini findings being presented this week at the Division for Planetary Sciences Meeting of the American Astronomical Society held in Pasadena, Calif. include several new faint ring structures formed by processes acting on and within Saturn's moons and main rings.

A series of unique observations gathered in mid-September by NASA's Saturn-orbiting Cassini spacecraft as it drifted slowly through Saturn's shadow, allowed the entire ring system to be seen from a perspective that highlights microscopic ring particles: in a number of cases, particles only recently released into Saturn orbit. While observing from this locale, Cassini spotted, a single faint new ring, announced previously, in the shared orbit of the moons Janus and Epimetheus.

Researchers are now ecstatic to find even more rings. A second new diffuse but narrow ring is coincident with the orbit of the tiny moon Pallene, also discovered by Cassini's imaging cameras and only 4 kilometers (2.5 miles) across. Curiously, another similar-sized moon called Methone, discovered earlier in the mission in roughly the same region, does not seem to sport a ring.........

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October 10, 2006, 10:04 PM CT

Gems Of Knowledge

Gems Of Knowledge
By processing vast amounts of data, computers helped astronomers make new discoveries about the universe. Now they're helping banks and other companies learn more about their customers.

As telescopes scan the heavens they generate huge amounts of data. Take the Hubble Space Telescope, for example. It produces about 1,000 gigabytes of data each year - enough to fill more than 200 million pages. Newer telescopes generate even more.

So what does all this data tell us? That's the question PPARC asked scientists at the University of Edinburgh more than 10 years ago.

All and nothing.

The answer is both all and nothing.

Like other scientific instruments, telescopes only give us the basic facts. They report everything they find - the positions of the objects in space, their brightness and more. And they report it all as accurately as they are able.

Unfortunately telescopes don't explain anything. Why are the stars where they are? What makes them move? Which stars are in which galaxy? And why does their brightness change? Telescopes haven't a clue.

To answer questions like these, astronomers have to put the facts together. Patterns in the data give them vital clues about how the universe works. The problem is that there is so much data to look through.........

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October 10, 2006, 9:25 PM CT

Nobelists' Work Supports Big-bang Theory

Nobelists' Work Supports Big-bang Theory
MIT alumnus George F. Smoot has been awarded the 2006 Nobel Prize in physics, together with John C. Mather, for work that looks back into the infancy of the universe and attempts to gain some understanding of the origin of galaxies and stars.

The work, based on measurements of the cosmic microwave background radiation made with NASA's COBE satellite, provides increased support for the big-bang theory of the origin of the universe. The COBE (Cosmic Background Explorer) measurements also mark the inception of cosmology as a precise science. For the first time, cosmological calculations could be compared with data from real measurements.

As per the big bang scenario, the cosmic microwave background radiation is a relic of the earliest phase of the universe. Immediately after the big bang itself, the universe can be in comparison to a glowing body emitting radiation at a temperature of almost 3,000 degrees Celsius.

Since then, the radiation has cooled as the universe has expanded. The background radiation we can measure today corresponds to a temperature that is barely 2.7 degrees above absolute zero. The new Nobel laureates were able to calculate this temperature thanks to the COBE measurements.

COBE also had the task of seeking small variations of temperature in the cosmic background radiation in different directions. Extremely small differences of this kind--in the range of a hundred-thousandth of a degree--offer an important clue to how the galaxies came into being. The variations in temperature measured by COBE show us how the matter in the universe began to "aggregate." This was necessary if the galaxies, stars and ultimately life forms like us were to be able to develop.........

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October 9, 2006, 9:19 PM CT

Disks Around Stars

Disks Around Stars
The NASA/ESA Hubble Space Telescope, in collaboration with ground-based observatories, has at last confirmed what philosopher Emmanuel Kant and scientists have long predicted: that planets form from debris disks around stars.

More than 200 years ago, the philosopher Emmanuel Kant first proposed that planets are born from disks of dust and gas that swirl around their home stars. Though astronomers have detected more than 200 extrasolar planets and have seen many debris disks around young stars, they have yet to observe a planet and a debris disk around the same star. Now, the NASA/ESA Hubble Space Telescope, in collaboration with ground-based observatories, has at last confirmed what Kant and scientists have long predicted: that planets form from debris disks around stars.

The Hubble observations by an international team of astronomers led by G. Fritz Benedict and Barbara E. McArthur of the University of Texas, Austin, USA, show for the first time that a planet is aligned with its star's circumstellar disk of dust and gas. The planet, detected in year 2000, orbits the nearby Sun-like star Epsilon Eridani, located 10.5 light-years from Earth in the constellation Eridanus. The planet's orbit is inclined 30 degrees to Earth, the same angle at which the star's disk is tilted. The results will appear in the recent issue of the Astronomical Journal.........

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October 8, 2006, 6:43 PM CT

Detailed view of Victoria Crater

Detailed view of Victoria Crater
With stunningly powerful vision, the HiRISE camera on NASA's Mars Reconnaissance Orbiter has taken a remarkable picture that shows the exploration rover Opportunity poised on the rim of Victoria crater on Mars.

The High Resolution Imaging Science Experiment (HiRISE) camera detailed the entire 800-meter (roughly half-mile) Victoria crater and the rover -- down to its rover tracks and shadows -- in a single high-resolution image taken Wednesday (Oct. 3).

Alfred S. McEwen of the University of Arizona Lunar and Planetary Laboratory released portions of the image that show views of the rover and crater at a NASA press conference in Washington, D.C., today. McEwen is principal investigator for HiRISE, which is operated from UA's Lunar and Planetary Laboratory in Tucson.

"We're poised to have a fantastic mission, and we're not even at prime science mission yet," McEwen said at NASA press briefing this morning. "This was our very first attempt to image 'off-nadir' (at an angle as opposed to straight down), and it worked fabulously well," McEwen added. "It's been an exciting week".

The HiRISE images for Victoria crater are available online at http://hiroc.lpl.arizona.edu/images/TRA/TRA_000873_1780/........

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