June 1, 2006, 6:43 PM CT

Huge Crater Found Under Ice

Planetary scientists have found evidence of a meteor impact much larger and earlier than the one that killed the dinosaurs -- an impact that they believe caused the biggest mass extinction in Earth's history.

The 300-mile-wide crater lies hidden more than a mile beneath the East Antarctic Ice Sheet. And the gravity measurements that reveal its existence suggest that it could date back about 250 million years -- the time of the Permian-Triassic extinction, when almost all animal life on Earth died out.

Its size and location -- in the Wilkes Land region of East Antarctica, south of Australia -- also suggest that it could have begun the breakup of the Gondwana supercontinent by creating the tectonic rift that pushed Australia northward.

Scientists believe that the Permian-Triassic extinction paved the way for the dinosaurs to rise to prominence. The Wilkes Land crater is more than twice the size of the Chicxulub crater in the Yucatan peninsula, which marks the impact that may have ultimately killed the dinosaurs 65 million years ago. The Chicxulub meteor is thought to have been 6 miles wide, while the Wilkes Land meteor could have been up to 30 miles wide -- four or five times wider.

"This Wilkes Land impact is much bigger than the impact that killed the dinosaurs, and probably would have caused catastrophic damage at the time," said Ralph von Frese, a professor of geological sciences at Ohio State University.........

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June 1, 2006, 6:38 PM CT

From Dark To Bright And Red To White

Cassini's landmark investigation of Saturn's yin-yang moon Iapetus, with its bright and dark hemispheres, continues to provide insights into the nature of this intriguing body.

These two views of Iapetus primarily show terrain in the southern part of the moon's dark leading hemisphere -- the side of Iapetus that is coated with dark material. The bright south pole of Iapetus is visible, along with some terrain (at the bottom) that lies on the bright trailing hemisphere.

The dark terrain known as Cassini Regio is uniformly dark between the equator and about 30 degrees south latitude. From there down to about 50 to 60 degrees south latitude, the dark material looks "patchy" because south-facing crater walls are bright (being largely devoid of the dark material). South of this region, only some northward-facing crater walls are still dark, while the bright terrain has a somewhat reddish color.

See Dark-stained Iapetus for an up-close view of this transition in the northern hemisphere.

Beyond 90 degrees south (i.e., on the trailing side), the reddish color becomes white. The region at the bottom of the color view presented here shows this "color boundary" in the bright terrain, which also marks the boundary between the leading and trailing hemispheres.........

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May 30, 2006, 11:53 PM CT

Finding Fourth Dimension of Space

Researchers at Duke and Rutgers universities have developed a mathematical framework they say will enable astronomers to test a new five-dimensional theory of gravity that competes with Einstein's General Theory of Relativity.

Charles R. Keeton of Rutgers and Arlie O. Petters of Duke base their work on a recent theory called the type II Randall-Sundrum braneworld gravity model. The theory holds that the visible universe is a membrane (hence "braneworld") embedded within a larger universe, much like a strand of filmy seaweed floating in the ocean. The "braneworld universe" has five dimensions -- four spatial dimensions plus time -- compared with the four dimensions -- three spatial, plus time -- laid out in the General Theory of Relativity.

The framework Keeton and Petters developed predicts certain cosmological effects that, if observed, should help researchers validate the braneworld theory. The observations, they said, should be possible with satellites scheduled to launch in the next few years.

If the braneworld theory proves to be true, "this would upset the applecart," Petters said. "It would confirm that there is a fourth dimension to space, which would create a philosophical shift in our understanding of the natural world".

The scientists' findings appeared May 24, 2006, in the online edition of the journal Physical Review D. Keeton is an astronomy and physics professor at Rutgers, and Petters is a mathematics and physics professor at Duke. Their research is funded by the National Science Foundation.........

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May 30, 2006, 6:45 AM CT

A Fleet Of Solar Observatories

New funding, to extend the mission of ESA's venerable solar watchdog SOHO, will ensure it plays a leading part in the fleet of solar spacecraft scheduled to be launched over the next few years.

Since its launch on 2 December 1995, The Solar and Heliospheric Observatory (SOHO) has provided an unprecedented view of the Sun - and not just the side facing the Earth. Two teams have now developed techniques for using SOHO to recreate the conditions on the far side of the Sun. The new funding will allow its mission to be extended from April 2007 to December 2009.

Despite being over ten years old now, SOHO just keeps on working, monitoring the activity on the Sun and allowing researchers to see inside the Sun by recording the seismic waves that ripple across the surface of our nearest star.

More than 2300 researchers have used data from the solar observatory to forward their research, publishing over 2400 scientific papers in peer-reviewed journals. During the last two years, at least one SOHO paper has been accepted for publication every working day.

"This mission extension will allow SOHO to cement its position as the most important spacecraft in the history of solar physics," says Bernhard Fleck, SOHO's project scientist, "There is a lot of valuable work for this spacecraft still to do."........

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May 27, 2006, 10:29 AM CT

Discovery Moves to Launch Pad

The Space Shuttle Discovery stands at its launch pad at NASA's Kennedy Space Center, Fla. The shuttle arrived at 8:30 p.m. EDT Friday on top of a giant vehicle known as the crawler transporter.

"Rollout of Space Shuttle Discovery signifies the last major processing milestone in preparation for our next mission, STS-121," said Space Shuttle Program Manager Wayne Hale. "The entire team has worked tremendously hard to ensure we were prepared to move to the pad, and we are excited to continue moving toward a July launch."

The crawler transporter began carrying Discovery out of Kennedy's Vehicle Assembly Building at 12:45 p.m. Friday. The crawler's maximum speed during the 4.2-mile journey was less than 1 mph.

While at the pad, the shuttle will undergo final testing and hardware integration previous to launch, as well as a "hot fire" test of the auxiliary power units to ensure they are properly functioning. The rotating service structure then will be moved back around the vehicle to protect it from potential damage and the elements.

Discovery's launch to the International Space Station is targeted for July 1, with a launch window that extends until July 19. During the 12-day mission, Discovery's crew will test new hardware and techniques to improve shuttle safety, as well as deliver supplies and make repairs to the station.........

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May 24, 2006, 6:32 PM CT

Generations Of Astronomers Survey The Stars

The speeds of stars reveal where they were born," said George Seabroke, a graduate student at the Institute of Astronomy in Cambridge. "We're trying to find out whether stars in our own Milky Way galaxy were actually made here or whether some of them existed in other galaxies, before becoming part of our Galaxy. Such a large survey wasn't possible in my great-great-grandfather's era."

Current galaxy formation theories predict that some of these other galaxies were cannibalised by the Milky Way a long time ago as it was growing, leaving their very old stars where we see them today. Uncovering these fossil remains will reveal the history of our Galaxy - a practice known as Galactic Archaeology.

In order to undertake a survey of this scope, astronomers are participating in the RAdial Velocity Experiment (RAVE). This ambitious spectroscopic survey is intended to measure, over the next few years, radial velocities and stellar atmosphere parameters (temperature, metallicity, surface gravity) of up to one million stars passing near the Sun.

For the last three years, RAVE has been using the unique capabilities of the 'six degree field' (6dF) multi-object spectrograph on the 1.2-m UK Schmidt Telescope of the Anglo-Australian Observatory, sited at Siding Spring Observatory in New South Wales, Australia.........

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May 23, 2006, 8:43 PM CT

Moonrocks that Breath

An early, persistent problem noted by Apollo astronauts on the Moon was dust. It got everywhere, including into their lungs. Oddly enough, that may be where future Moon explorers get their next breath of air: The moon's dusty layer of soil is nearly half oxygen.

"All you have to do is vaporize the stuff," says Eric Cardiff of NASA's Goddard Space Flight Center. He leads one of several teams developing ways to provide astronauts oxygen they'll need on the Moon and Mars. (See the Vision for Space Exploration.).

Lunar soil is rich in oxides. The most common is silicon dioxide (SiO2), "like beach sand," says Cardiff. Also plentiful are oxides of calcium (CaO), iron (FeO) and magnesium (MgO). Add up all the O's: 43% of the mass of lunar soil is oxygen.

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Cardiff is working on a technique that heats lunar soils until they release oxygen. "It's a simple aspect of chemistry," he explains. "Any material crumbles into atoms if made hot enough." The technique is called vacuum pyrolysis--pyro means "fire", lysis means "to separate".

"Many factors make pyrolysis more attractive than other techniques," Cardiff explains. "It requires no raw materials to be brought from Earth, and you don't have to prospect for a particular mineral." Simply scoop up what's on the ground and apply the heat.........

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May 22, 2006, 11:17 PM CT

Spitzer Spies Remnants of a Shy Star

Big stars commonly aren't shy about anything, not even death. At the end of their lives, they throw explosive tantrums, called supernovae, flinging abundant amounts of hot gas and radiation into space. Remnants of this cosmic fury can last for several thousand years and be easily detected by most telescopes used by professional astronomers.

But not all stars like attention. Thirty thousand light-years away in the Cepheus constellation, astronomers think they've found a massive star whose death barely made a "peep." Remnants of this shy star's supernova would have gone completely unnoticed if the infrared eyes of NASA's Spitzer Space Telescope hadn't accidentally stumbled upon them.

"This source is really trying to avoid detection," said Dr. Patrick Morris of NASA's Herschel Science Center at the California Institute of Technology in Pasadena, Calif. He is the lead author of a paper on the discovery, which was reported in the April 2006 Astrophysical Journal Letters.

What makes this lone star so unusual? Morris suspects that it sits away from the mobs of stars that occupy the main disk of our Milky Way galaxy. Our galaxy's disk is a crowded and dusty place, whereas the regions above and below are comparatively dust free. It is this dust that allows exploding stars to be readily detected. Expelled material violently collides with surrounding dust, giving off bright light of various wavelengths. The putative supernova remnant discovered by Spitzer did not have enough dust around it to amplify its final death throes.........

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May 18, 2006, 8:50 PM CT

Explosions In Gigantic Dusty Potato Crisp

ESO's Very Large Telescope, equipped with the multi-mode FORS instrument, took an image of NGC 3190, a galaxy so distorted that astronomers gave it two names. And as if to prove them right, in 2002 it fired off, almost simultaneously, two stellar explosions, a very rare event.

This beautiful edge-on spiral galaxy with tightly wound arms and a warped shape that makes it resemble a gigantic potato crisp lies in the constellation Leo ('the Lion') [1] and is approximately 70 million light years away. It is the dominant member of a small group of galaxies known as Hickson 44, named after the Canadian astronomer, Paul Hickson. In addition to NGC 3190 [2], Hickson 44 consists of one elliptical and two spiral galaxies. These are, however, slightly out of the field of view and therefore not visible here.

In 1982, Hickson published a catalogue of over 400 galaxies found in compact, physically-related groups of typically 4 to 5 galaxies per group (see the image of Robert's Quartet in ESO PR Photo 34/05 as another example). Such compact groups allow astronomers to study how galaxies dynamically affect each other, and help them test current ideas on how galaxies form. One idea is that compact groups of galaxies, such as Hickson 44, merge to form a giant elliptical galaxy, such as NGC 1316 (see ESO PR 17/00).........

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May 18, 2006, 8:36 PM CT

Looking Beyond The Birth Of The Universe

As per Einstein's general theory of relativity, the Big Bang represents The Beginning, the grand event at which not only matter but space-time itself was born. While classical theories offer no clues about existence before that moment, a research team at Penn State has used quantum gravitational calculations to find threads that lead to an earlier time. "General relativity can be used to describe the universe back to a point at which matter becomes so dense that its equations don't hold up," says Abhay Ashtekar, Holder of the Eberly Family Chair in Physics and Director of the Institute for Gravitational Physics and Geometry at Penn State. "Beyond that point, we needed to apply quantum tools that were not available to Einstein." By combining quantum physics with general relativity, Ashtekar and two of his post-doctoral researchers, Tomasz Pawlowski and Parmpreet Singh, were able to develop a model that traces through the Big Bang to a shrinking universe that exhibits physics similar to ours.

In research published in the current issue of Physical Review Letters, the team shows that, previous to the Big Bang, there was a contracting universe with space-time geometry that otherwise is similar to that of our current expanding universe. As gravitational forces pulled this prior universe inward, it reached a point at which the quantum properties of space-time cause gravity to become repulsive, rather than attractive. "Using quantum modifications of Einstein's cosmological equations, we have shown that in place of a classical Big Bang there is in fact a quantum Bounce," says Ashtekar. "We were so surprised by the finding that there is another classical, pre-Big Bang universe that we repeated the simulations with different parameter values over several months, but we found that the Big Bounce scenario is robust".........

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