May 11, 2008, 10:22 AM CT

Evolution of "gas giants"

By shooting the high-energy Omega laser onto precompressed samples of planetary fluids, researchers are gaining a better understanding of the evolution and internal structure of Jupiter, Saturn and extrasolar giant planets.

The properties of dense helium (He) - which happens to be a principal constituent of giant gas planets like Jupiter - at thermodynamic conditions between those of condensed matter and high-temperature plasmas are theoretically challenging and unexplored experimentally.

Laboratory researchers collaborating with scientists at the Laboratory for Laser Energetics, CEA France and UC Berkeley were able to determine the equation of state (EOS) for fluid He at pressures above 100 GPa (one million times more pressure than the Earth's atmosphere - one GPa (gigapascal) equals 10,000 atmospheres).

The only prior high temperature and pressure He EOS data available for constraining planetary models waccording toformed at LLNL by Bill Nellis and his team using a two-stage gas gun. However, those earlier experiments used cryogenic techniques at ambient pressure so their densities were significantly lower than those achieved with the precompressed samples. Also, the final pressures, 16 GPa for a single shock, were significantly lower than the new laser shock data......... Posted by: Kevin      Read more         Source

April 28, 2008, 8:27 PM CT

Satellite Mission To Map Earth's Water Cycle

MIT Professor Dara Entekhabi will lead the science team designing a NASA satellite mission to make global soil moisture and freeze/thaw measurements, data essential to the accuracy of weather forecasts and predictions of global carbon cycle and climate. NASA announced recently that the Soil Moisture Active-Passive mission (SMAP) is scheduled to launch December 2012.

At present, researchers have no network for gathering soil moisture data as they do for rainfall, winds, humidity and temperature. Instead, that data is gathered only at a few scattered points around the world.

"Soil moisture is the lynchpin of the water, energy and carbon cycles over land. It is the variable that links these three cycles through its control on evaporation and plant transpiration. Global monitoring of this variable will allow a new perspective on how these three cycles work and vary together in the Earth system," said Entekhabi, director of the Parsons Laboratory for Environmental Science and Engineering in MIT's Department of Civil and Environmental Engineering.

"Additionally because soil moisture is a state variable that controls both water and energy fluxes at the land surface, we anticipate that assimilation of the global observations will improve the skill in numerical weather prediction, particularly for events that are influenced by these fluxes at the base of the atmosphere," he said......... Posted by: Brooke      Read more         Source

March 9, 2008, 4:45 PM CT

GLAST Spacecraft Arrives in Florida

NASA's Gamma-ray Large Area Space Telescope, or GLAST, arrived Tuesday at the Astrotech payload processing facility near the Kennedy Space Center to begin final preparations for launch. Liftoff of GLAST aboard a Delta II rocket is currently targeted for 11:45 a.m. EDT on May 16.

GLAST is a collaborative mission with the U.S. Department of Energy, international partners from France, Gera number of, Italy, Japan and Sweden, and numerous academic institutions from the U.S. and abroad. The spacecraft will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts.

The milestones to be accomplished over the next two months include attaching the Ku-band communications antenna and the two sets of solar arrays, a complete checkout of GLAST's scientific instruments, installing the spacecraft's battery, and loading aboard the observatory's propellant. These activities will be performed by General Dynamics, builder of the spacecraft for NASA. GLAST currently is scheduled to be transported to Pad 17-B at Cape Canaveral Air Force Station on May 1.

The rocket that will launch GLAST is a Delta II 7920-H, manufactured and prepared for launch by United Launch Alliance. It is a heavier-lift model of the standard Delta II that uses larger solid rocket boosters. The first stage is scheduled to be erected on Pad 17-B the week of March 17......... Posted by: Brooke      Read more         Source

March 9, 2008, 4:43 PM CT

Canadian astronomers on hunt for meteor

Astronomers from The University of Western Ontario in London, Ontario, have captured rare video of a meteor falling to Earth.

The Physics and Astronomy Department at Western has a network of all-sky cameras in Southern Ontario that scan the sky monitoring for meteors. Associate Professor Peter Brown, who specializes in the study of meteors and meteorites, says that Wednesday evening (March 5) at 10:59 p.m. EST these cameras captured video of a large fireball and the department has also received many calls and emails from people who actually saw the light.

Brown along with Wayne Edwards, a post doctorate student, hope to enlist the help of local residents in recovering one or more possible meteorites that may have crashed in the Parry Sound area.

Most meteoroids burn up by the time they hit an altitude of 60 or 70 kilometres from Earth, says Edwards. We tracked this one to an altitude of about 24 kilometres so we are pretty sure there are at least one, and possibly a number of meteorites, that made it to the ground.

Edwards says the lab can narrow the ground location where the meteorite would have fallen, to about 12 square kilometres and have created a map that may assist in locating the meteorite. The rock, or rocks, would probably weigh a kilogram or slightly more......... Posted by: Brooke      Read more         Source

February 24, 2008, 10:25 PM CT

The light and dark of Venus

Venus Express has revealed a planet of extraordinarily changeable and extremely large-scale weather. Bright hazes appear in a matter of days, reaching from the south pole to the low southern latitudes and disappearing just as quickly. Such 'global weather', unlike anything on Earth, has given researchers a new mystery to solve.

The cloud-covered world of Venus is all but a featureless, unchangeable globe at visible wavelengths of light. Switch to the ultraviolet and it reveals a truly dynamic nature. Transient dark and bright markings stripe the planet, indicating regions where solar ultraviolet radiation is absorbed or reflected, respectively.

Venus Express watches the behaviour of the planet's atmosphere with its Venus Monitoring Camera (VMC). It has seen some amazing things. In July 2007, VMC captured a series of images showing the development of the bright southern haze. Within days, the high-altitude veil continually brightened and dimmed, moving towards equatorial latitudes and back towards the pole again.

Such global weather suggests that fast dynamical, chemical and microphysical processes are at work on the planet. During these episodes, the brightness of the southern polar latitudes increased by about a third and faded just as quickly, as sulphuric acid particles coagulate......... Posted by: Brooke      Read more         Source

January 14, 2008, 3:19 PM CT

Pulses in Saturn's rings

In 2005, the Cassini spacecraft began a series of experiments to profile ring structure and measure the size distribution of particles in Saturn's rings. During these experiments, Cassini flew behind the ring plane and transmitted radio waves through ring particles to Earth. Researchers on Earth analyzed the signals' diffraction patterns to help determine properties of the rings. Thomson et al.

Typically study these data and find that in limited regions of rings a and b (a and b lie close to the outside of saturn's ring system), the diffraction pattern reveals the presence of fine-scale structures that are characterized by periodic radial variation in optical depth. They define specific periods of variation in optical depth for distinct regions of rings A and B. Past research suggests that the dynamic interplay of gravitational and collisional forces leads to the formation of viscous oscillations and gravity wakes in Saturn's rings. The authors speculate that the number density of ring particles contracts and relaxes to form periodic structures that affect the radio signals seen on Earth......... Posted by: Brooke      Read more         Source

November 29, 2007, 10:53 PM CT

Youngest solar systems detected

ANN ARBOR, Mich.---Astronomers at the University of Michigan have found what are thought to besome of the youngest solar systems yet detected.

The systems are around the young stars UX Tau A and LkCa 15, located in the Taurus star formation region just 450 light years away. Using a telescope that measures levels of infrared radiation, the scientists noticed gaps in the protoplanetary disks of gas and dust surrounding these stars. They say those gaps are most likely caused by infant planets sweeping those areas clear of debris.

A paper on the findings by astronomy doctoral student Catherine Espaillat, professor Nuria Calvet, and their colleagues is reported in the Dec. 1 issue of Astrophysical Journal Letters.

"Previously, astronomers were seeing holes at the centers of protoplanetary disks and one of the theories was that the star could be photoevaporating that material," said Espaillat, first author of the paper.

Photoevaporation refers to the process of heating up the dust and gas in the surrounding cloud until it evaporates and dissipates.

"We observed that in some stars, including these two, instead of a hole, there's a gap," Espaillat said. "It's more like a lane has been cleared within the disk. That is not consistent with photoevaporation. The existence of planets is the most probable theory that can explain this structure"......... Posted by: Brooke      Read more         Source

November 13, 2007, 9:28 PM CT

Regional variation in warming from sun

A NASA satellite designed, built and controlled by the University of Colorado at Boulder is expected to help researchers resolve wide-ranging predictions about the coming solar cycle peak in 2012 and its influence on Earth's warming climate, as per the chief scientist on the project.

Senior Research Associate Tom Woods of CU-Boulder's Laboratory for Atmospheric and Space Physics said the brightening of the sun as it approaches its next solar cycle maximum will have regional climatic impacts on Earth. While some researchers predict the next solar cycle -- expected to start in 2008 -- will be significantly weaker than the present one, others are forecasting an increase of up to 40 percent in the sun's activity, said Woods.

Woods is the principal investigator on NASA's $88 million Solar Radiation and Climate Experiment, or SORCE, mission, launched in 2003 to study how and why variations in the sun affect Earth's atmosphere and climate. In August, NASA extended the SORCE mission through 2012. The extension provides roughly $18 million to LASP, which controls SORCE from campus by uploading commands and downloading data three times daily to the Space Technology Building in the CU Research Park.

Solar cycles, which span an average of 11 years, are driven by the amount and size of sunspots present on the sun's surface, which modulate brightness from the X-ray to infrared portion of the electromagnetic spectrum. The current solar cycle peaked in 2002......... Posted by: Tyler      Read more         Source

November 1, 2007, 8:26 PM CT

Phoenix:Tasks En Route to Mars Include Course Tweak, Gear Checks

NASA's Phoenix Mars Lander, launched on Aug. 4 and headed to Mars, fired its four trajectory correction thrusters Wednesday for only the second time. The 45.9-second burn nudged the spacecraft just the right amount to put it on a course to arrive at the red planet seven months from today.

At Mars, Phoenix will face a challenging 7-minute descent through the atmosphere to land in the far north on May 25, 2008. After landing, it will use a robotic digging arm and other instruments during a three-month period to investigate whether icy soil of the Martian arctic could have ever been a favorable environment for microbial life. The solar-powered lander will also look for clues about the history of the water in the ice and will monitor weather as northern Mars' summer progresses toward fall.

The second course adjustment had been postponed a week to allow time for carefully returning the spacecraft to full operations after a cosmic-ray strike disrupted a computer memory chip Oct. 6. Experiences with prior spacecraft have shown hits by cosmic rays are a known hazard in deep space. The Phoenix spacecraft properly followed its onboard safety programming by putting itself into a precautionary standby state when the event occurred. Mission controllers then followed step-by-step procedures to understand the cause and resume regular operations......... Posted by: Brooke      Read more         Source

October 28, 2007, 4:18 PM CT

Mars With Ice, Shaken, Not Stirred

Mars, like Earth, is a climate-fickle water planet. The main difference, of course, is that water on the frigid Red Planet is rarely liquid, preferring to spend almost all of its time traveling the world as a gas or churning up the surface as ice. That's the global picture literally and figuratively coming into much sharper focus as various Mars-orbiting cameras send back tomes of unprecedented super high-resolution imagery of ever vaster tracts of the planet's surface.

What were just a few years ago small hints about Mars' water and climate, as seen in a few "postage-stamp" high-resolution images and topography, have given way to broader theory that explains not only the features seen on the planet today, but imply a dynamic history of Martian climate change.

"When you have postage stamps, it's like studying a hair on an arm instead of the whole arm," said Mars researcher James Head III of Brown University. Head will present the latest integrated global view of Martian surface features and how they fit with Martian climate models on Sunday, 28 October 2007, at the Geological Society of America Annual Meeting in Denver.

The pictures now reveal a range of ice-made features that show a strong preference to certain latitudes, Head explains. As on Earth, latitude-dependent features can mean only one thing: latitude-dependent climate......... Posted by: Brooke      Read more         Source

October 24, 2007, 7:31 PM CT

First-Known Belt Of Moonlets In Saturn Rings

A narrow belt harboring moonlets as large as football stadiums discovered in Saturn's outermost ring probably resulted when a larger moon was shattered by a wayward asteroid or comet eons ago, as per a University of Colorado at Boulder study.

Images taken by a camera onboard the NASA Cassini spacecraft revealed a series of eight propeller-shaped "wakes" in a thin belt of the outermost "A" ring, indicating the presence of corresponding moonlets, said CU-Boulder Research Associate Miodrag Sremcevic, lead author of the study reported in the Oct. 25 issue of Nature. The propeller wakes highlight tiny areas of the belt where ring material has been perturbed by the gravitational forces caused by individual moonlets, Sremcevic said.

The team calculated that there likely are thousands of moonlets ranging in size from semi-trailers to sports arenas embedded in the "A" ring's thin moonlet belt that circles the planet. At about 2,000 miles across, the belt of moonlets is only about 1/80th the diameter of Saturn's total ring system, which at roughly 155,000 miles across would stretch about two-thirds of the way from Earth to the moon.

"This is the first evidence of a moonlet belt in any of Saturn's rings," said Sremcevic of CU-Boulder's Laboratory for Atmospheric and Space Physics. "We have firmly established these moonlets exist in a relatively narrow region of the "A" ring, and the evidence indicates they are remnants of a larger moon that was shattered by a meteoroid or comet."........ Posted by: Brooke      Read more         Source

October 8, 2007, 9:28 AM CT

Satellite methods for monitoring volcanic activity

The central part of the Andes situated between southern Peru and Chile bears 50 active or potentially volcanoes, spread along a 1500 km-long arc. These volcanic structures mostly rise to between 4000 and 7000 m, are very remote with abrupt slopes and are often cloaked in snow. Few studies have been made on them as such conditions make field surveying extremely difficult. A team of IRD scientists working in partnership with the University of Chile (Santiago) and the Observatoire de Physique du Globe of Clermont-Ferrand (1) focused special attention on the Lastarria-Cordon del Azufre volcanic complex. With a surface area of 1600 km, it is situated in the central Andes Cordillera at the border between Argentina and Chile near Antofagasta.

Research projects on deformations of the earth crust, conducted in this region between 1992 and 2000 by a North American team, had led to the detection of a long wavelength signal over the areas topography, extracted from analysis of data collected by the European Space Agency (ESA) satellite ERS-1. This deformation would correspond to crustal inflation affecting the whole Lastarria-Cordon del Azufre complex. Eventhough this volcano is not considered as active, as the last eruption dates back 9000 years, such inflation could express an underlying activity correlation to the dynamics of a functioning magma chamber......... Posted by: Tyler      Read more         Source

October 2, 2007, 10:22 PM CT

Light on mysterious 'dark matter'

Weve all been taught that our bodies, the Earth, and in fact all matter in the universe is composed of tiny building blocks called atoms. Now imagine if this werent the case. This mind-bending concept is at the core of the scientific research that one Florida State University professor -- and hundreds of his colleagues all over the world -- are pursuing.

Recent scientific breakthroughs have shown that most of the matter in the universe -- about four-fifths -- is not made up of atoms, but of something else, called dark matter, said Howard Baer, FSUs J.D. Kimel Professor of Physics. The evidence for dark matter is now overwhelming, and the mandatory amount of dark matter is becoming precisely known.

Baer explained that dark matter is believed to exist in the form of tiny particles that do not interact with light. Because they dont emit or reflect electromagnetic radiation the way atomic, or baryonic, matter does, these dark matter particles havent been directly observed. However, researchers have long theorized their existence based on their gravitational effects on visible matter throughout the universe.

For example, the gravitational effect of dark matter makes galaxies spin faster than one would otherwise expect, Baer said. Also, dark matters gravitational field distorts the light of objects behind it -- creating the so-called lensing effect. By measuring these sorts of phenomena, we can tell that the universe is full of some sort of stuff that we just cant see......... Posted by: Brooke      Read more         Source

October 1, 2007, 10:21 PM CT

The dark matter of the universe has a long lifetime

New research from the Niels Bohr Institute presents new information that adds another piece of knowledge to the jigsaw puzzle of the dark mystery of the universe dark matter. The research has just been reported in the scientific journal Physical Review Letters.

The universe consists not just of visible celestial bodies, stars, planets and galaxies. It also has a mystical fellow player dark matter. The astronomers can measure that the dark matter exists in big quantities but no one knows what it is, nobody has seen it. It does not emit light and it does not reflect light. It is invisible. It is a mystery and the scientists have a number of theories.

The dark matter has caused the scientists headaches for decades since it was detected in the 1970s, and there is intense research into the phenomena. It is invisible but it has got mass, and thus it has got gravitation that can be measured. By analysing the galaxies it is possible to weigh them, and it turns out that by far the greatest matter of the collective mass of the galaxy is dark matter.

Just like stars get together in galaxies, the galaxies get together in clusters of galaxies of up to several thousand galaxies. The astrophysicist Signe Riemer-Srensen, PhD student at the Niels Bohr Institute, has analysed two clusters of galaxies that collide......... Posted by: Brooke      Read more         Source

Fri, 28 Sep 2007 01:42:16 GMT

The Moon in Hypersaturated Color

Via ApodVia Apod- Quoted - The Moon in Hypersaturated Color Posted by: Zinzi      Read more     Source

September 18, 2007, 5:33 AM CT

Satellites witness lowest Arctic ice coverage in history

The area covered by sea ice in the Arctic has shrunk to its lowest level this week since satellite measurements began nearly 30 years ago, opening up the Northwest Passage - a long-sought short cut between Europe and Asia that has been historically impassable.

In the mosaic image above, created from nearly 200 images acquired in early September 2007 by the Advanced Synthetic Aperture Radar (ASAR) instrument aboard ESA's Envisat satellite, the dark gray colour represents the ice-free areas while green represents areas with sea ice.

Leif Toudal Pedersen from the Danish National Space Centre said: "We have seen the ice-covered area drop to just around 3 million sq km which is about 1 million sq km less than the prior minima of 2005 and 2006. There has been a reduction of the ice cover over the last 10 years of about 100 000 sq km per year on average, so a drop of 1 million sq km in just one year is extreme.

"The strong reduction in just one year certainly raises flags that the ice (in summer) may disappear much sooner than expected and that we urgently need to understand better the processes involved."

Arctic sea ice naturally extends its surface coverage each northern winter and recedes each northern summer, but the rate of overall loss since 1978 when satellite records began has accelerated......... Posted by: Tyler      Read more         Source

September 12, 2007, 8:09 PM CT

The mysterious ridges at the mouth of Tiu Valles

These images taken by the High Resolution Stereo Camera (HRSC) on board Mars Express show the mouth of the Tiu Valles channel system on the red planet.

The pictures were taken in orbit 3103 on 10 June 2006 with a ground resolution of approximately 16 metres per pixel.

The mouth of Tiu Valles is an estuary-like landform. On Earth, an estuary is the tidal mouth of a river valley, or the end that meets the sea and fresh water comes into contact with seawater. In such an area, tidal effects are evident.

Tiu Valles is located at approximately 27 degree North and 330 degree East. The sun illuminates the scene from the North West, the lower left-hand side in the image.

Tiu Valles originates in the equatorial chaotic terrains at the mouth, at the eastern end of Valles Marineris. The morphology of this chaotic terrain is dominated by large-scale remnant massifs, which are large relief masses that have been moved and weathered as a block. These are randomly oriented and heavily eroded.

From there, the region extends to the north over a distance of 1500 km before terminating in Chryse Planitia. Along with Kasei Valles and Ares Valles, Tiu Valles is one of the major outflow channels entering the Chryse Planitia plain.

The scene in the images covers an area of approximately 140 by 80 km at the mouth of Tiu Valles. The region was made famous in 1997 when rover Sojourner of NASA's Pathfinder mission landed about 600 km south-west of the mapped area......... Posted by: Brooke      Read more         Source

August 27, 2007, 9:16 PM CT

Hot Spots And Fires From Space

Hot spots across Southeastern Europe from 21 to 26 August have been detected with instruments aboard ESA satellites, which have been continuously surveying fires burning across the Earth's surface for a decade.

Working like thermometers in the sky, the Along Track Scanning Radiometer (ATSR) on ESA's ERS-2 satellite and the Advanced Along Track Scanning Radiometer (AATSR) on ESA's Envisat satellite measure thermal infrared radiation to take the temperature of Earth's land surfaces.

Temperatures exceeding 312ºK (38.85ºC) are classed as burning fires by AATSR, which is capable of detecting fires as small as gas flares from industrial sites because of their high temperature. Worldwide fire maps based on this data are available to users online in near-real time through ESA's ATSR World Fire Atlas (WFA).

Smoke from some of the fires included in the WFA fire map was detected during the same period by Envisat's Medium Resolution Imaging Spectrometer (MERIS) optical instrument. While working in Full Resolution mode to provide a spatial resolution of 300 metres, MERIS captured smoke plumes arising from fires raging across Greece's southern Peloponnese peninsula, where fires have claimed the lives of at least 60 people since they began four days ago.

These images are available on ESA's MIRAVI website, which gives access to Envisat's most recently acquired images. MIRAVI, short for MERIS Images RApid VIsualisation, tracks Envisat - the world's largest Earth Observation satellite - around the globe, generates images from the raw data collected by MERIS and provides them online within two hours. MIRAVI is free and requires no registration......... Posted by: Brooke      Read more         Source

August 26, 2007, 10:40 AM CT

Martian Soil Samples Could Have Biological Origin

A new interpretation of data from NASA's Viking landers indicates that 0.1% of the Martian soil tested could have a biological origin.

Dr Joop Houtkooper of the University of Giessen, Gera number of, believes that the subfreezing, arid Martian surface could be home to organisms whose cells are filled with a mixture of hydrogen peroxide and water. In a presentation at the European Planetary Science Congress in Potsdam on Friday 24th August, Dr Houtkooper will describe how he has used data from the Gas Exchange (GEx) experiment, carried by NASA's Viking landers, to estimate the biomass in the Martian soil.

Dr Houtkooper said, "The GEx experiment measured unexplained rises in oxygen and carbon dioxide levels when incubating samples. If we assume these gases were produced during the breakdown of organic material together with hydrogen peroxide solution, we can calculate the masses needed to produce the volume of gas measured. From that, we can estimate the total biomass in the sample of Martian soil. It comes out at little more than one part per thousand by weight, comparable to what is found in some permafrost in Antarctica. This might be detectable by instruments on the Phoenix lander, which will arrive at Mars in May next year".

Dr Houtkooper and his colleague, Dr Schulze-Makuch from Washington State University, suggest that a hydrogen peroxide-water based organism would be quite capable of surviving in the harsh Martian climate where temperatures rarely rise above freezing and can reach -150 degrees Celsius at the poles......... Posted by: Brooke      Read more         Source

August 26, 2007, 10:37 AM CT

Basalt In The Outer Asteroid Belt

Analysis of the chemical make up of two asteroids in the outer asteroid belt has thrown the classification system for these small bodies, which orbit between Mars and Jupiter, into disorder.

Dr Rene Duffard, who is presenting results at the European Planetary Science Congress in Potsdam on Wednesday 22nd August, said, "We appear to have detected basalt on the surface of these asteroids, which is very unusual for this part of the asteroid belt. We do not know whether we have discovered two basaltic asteroids with a very particular and previously unseen mineralogical composition or two objects of non basaltic nature that have to be included in a totally new taxonomic class".

The presence of basalt means that the asteroid must have melted partially at some time in the past, which implies that it was once part of a larger body which had internal heating processes. However, there do not appear to be other basaltic fragments in the region and, from spectral analysis, it is not clear whether the two are fragments of the same parent body or not.

Until recently, most of the known basaltic asteroids, which are classified as V-type, were believed to be fragments of Vesta, the second largest object in the asteroid belt. Since 2001, several V-type asteroids have been identified as not belonging to this Vesta family, including (1459) Magnya, the first basaltic object to be detected in the outer asteroid belt......... Posted by: Brooke      Read more         Source

August 21, 2007, 5:49 PM CT

Hurricane Dean tracked from space

ESA satellites are tracking the path of Hurricane Dean as it rips across the Caribbean Sea carrying winds as high as 260 km/h. The hurricane, which has already claimed eight lives, is forecast to slam into Mexico's Yucatan Peninsula on Tuesday morning.

Dean was upgraded early Tuesday to a Category 5 - the highest on the Saffir-Simpson scale - before pummelling the peninsula. Knowing the strength and path of hurricanes is critical for issuing timely warnings; satellites are the best means of providing data on the forces that power the storm, such as cloud structure, wind and wave fields, sea surface temperature and sea surface height.

Instruments aboard ESA's Envisat and ERS-2 satellites allow them to peer through hurricanes. Envisat carries both optical and radar instruments, enabling scientists to observe high-atmosphere cloud structure and pressure in the visible and infrared spectrum.

The Medium Resolution Imaging Spectrometer (MERIS) optical instrument shows the swirling cloud-tops of a hurricane, while radar instruments such as the Advanced Synthetic Aperture Radar (ASAR) pierce through the clouds to show how the wind fields shape the sea surface and estimate their likely destructive extent.

ERS-2 uses its radar scatterometer to observe the hurricane's underlying wind fields. The scatterometer instrument works by firing a trio of high-frequency radar beams down to the ocean, then analysing the pattern of backscatter reflected up again. Wind-driven ripples on the ocean surface modify the radar backscatter, and as the energy in these ripples increases with wind velocity, backscatter increases as well. Scatterometer results enable measurements not only of wind speed but also of direction across the water surface......... Posted by: Brooke      Read more         Source

August 3, 2007, 10:27 PM CT

Sensors Help Africa Tackle Water Shortage

Zambian water authorities are integrating information based on satellite imagery to alleviate water shortages. With inadequate information causing a number of water-related problems, an ESA project has generated a variety of environmental maps to provide local policy makers with the necessary tools for effective water resource management.

As part of the IWAREMA (Integrated Water Resource management for Zambia) project, funded through ESA's Data User Element, data from ESA's multispectral MERIS sensor aboard Envisat was used to create maps depicting existing water resources, suitable dam locations and land cover. The project is carried out by the Belgium Company GIM (Geographic Information Management) in partnership with the University of Zambia and the Zambian water authorities.

"The results of the IWAREMA project can be used to protect Zambia's ecosystems especially in the Kafue flats where wildlife, agricultural activities, fisheries and tourism compete for regulated water resources," Jack Nkhoma of Zambia's Department of Water Affairs said.

Having access to these maps allows authorities to determine the expansion of urban areas and loss of forest and agricultural areas as well as calculate the risk of erosion, change in water availability and percentage of surface water, which will allow for early flood warnings......... Posted by: Tyler      Read more         Source

August 3, 2007, 10:24 PM CT

The Planet, the Galaxy and the Laser

On the night of 21 July, ESO astronomer Yuri Beletsky took images of the night sky above Paranal, the 2600m high mountain in the Chilean Atacama Desert home to ESO's Very Large Telescope. The amazing images bear witness to the unique quality of the sky, revealing not only the Milky Way in all its splendour but also the planet Jupiter and the laser beam used at Yepun, one of the 8.2-m telescopes that make up this extraordinary facility.

"The images are not composite", emphasises Yuri Beletsky. "The camera was being tracked on the stars, which can be easily noticed if you look at the telescope domes on the image (they look a little fuzzy). The colour of the laser beam on the first image actually looks pretty close to what one can see on the sky with the unaided eye."

Most striking in the images is the wide band of stars called the Milky Way. Spanning more than 100 degrees in the first of these images, it shows the dust and stars that are part of our own Galaxy, a spiral galaxy containing about 100 billion stars.

In the middle of this image, two bright objects are also seen. The brighter of the two is the planet Jupiter. The other is the bright star Antares. Another bright star, Alpha Centauri, one of the closest stellar neighbours to the Sun, is visible at the middle-left edge of the image......... Posted by: Brooke      Read more         Source