Scientists Find Elusive Waves In Sun's Corona

Source:

http://www.sciencedaily.com/releases/2007/08/070830150113.htm

Science Daily — Scientists for the first time have observed elusive oscillations in the Sun's corona, known as Alfvén waves, that transport energy outward from the surface of the Sun. The discovery is expected to give researchers more insight into the fundamental behavior of solar magnetic fields, eventually leading to a fuller understanding of how the Sun affects Earth and the solar system.

The research, led by Steve Tomczyk of the National Center for Atmospheric Research (NCAR), is being published this week in Science.
"Alfvén waves can provide us with a window into processes that are fundamental to the workings of the Sun and its impacts on Earth," says Tomczyk, a scientist with NCAR's High Altitude Observatory.
Alfvén waves are fast-moving perturbations that emanate outward from the Sun along magnetic field lines, transporting energy. Although they have been detected in the heliosphere outside the Sun, they have never before been viewed within the corona, which is the outer layer of the Sun's atmosphere. Alfvén waves are difficult to detect partly because, unlike other waves, they do not lead to large-intensity fluctuations in the corona. In addition, their velocity shifts are small and not easily spotted.
"Our observations allowed us to unambiguously identify these oscillations as Alfvén waves," says coauthor Scott McIntosh of the Southwest Research Institute in Boulder. "The waves are visible all the time and they occur all over the corona, which was initially surprising to us."
Insights into the Sun
By tracking the speed and direction of the waves, researchers will be able to infer basic properties of the solar atmosphere, such as the density and direction of magnetic fields. The waves may provide answers to questions that have puzzled physicists for generations, such as why the Sun's corona is hundreds of times hotter than its surface.
The research also can help scientists better predict solar storms that spew thousands of tons of magnetized matter into space, sometimes causing geomagnetic storms on Earth that disrupt sensitive telecommunications and power systems. By learning more about solar disruptions, scientists may be able to better protect astronauts from potentially dangerous levels of radiation in space.
"If we want to go to the moon and Mars, people need to know what's going to happen on the Sun," Tomczyk says.
A powerful instrument
To observe the waves, Tomczyk and his coauthors turned to an instrument developed at NCAR over the last few years. The coronal multichannel polarimeter, or CoMP, uses a telescope at the National Solar Observatory in Sacramento Peak, New Mexico, to gather and analyze light from the corona, which is much dimmer than the Sun itself. It tracks magnetic activity around the entire edge of the Sun and collects data with unusual speed, making a measurement as frequently as every 15 seconds.
The instrument enabled the research team to simultaneously capture intensity, velocity, and polarization images of the solar corona. Those images revealed propagating oscillations that moved in trajectories aligned with magnetic fields, and traveled as fast as nearly 2,500 miles per second.
In addition to Tomczyk and McIntosh, the research team included scientists from the National Solar Observatory, University of Notre Dame, Framingham High School in Massachusetts, University of Michigan, and NCAR.
Article: S. Tomczyk, S.W. McIntosh, S.L. Keil, P.G. Judge, T. Schad, D.H. Seeley, J. Edmondson, "Alfvén Waves in the Solar Corona", Science, August 31, 2007
Note: This story has been adapted from a news release issued by National Center for Atmospheric Research.

Fausto Intilla

www.oloscience.com

Mars Exploration Rovers Resume Driving

Source:

http://www.sciencedaily.com/releases/2007/08/070829170103.htm

Science Daily — After six weeks of hunkering down during raging dust storms that limited solar power, both of NASA's Mars Exploration Rovers, Spirit and Opportunity, have resumed driving.

Opportunity advanced 13.38 meters (44 feet) toward the edge of Victoria Crater on Aug. 21. Mission controllers were taking advantage of gradual clearing of dust from the sky while also taking precautions against buildup of dust settling onto the rover.
"Weather and power conditions continue to improve, although very slowly for both rovers," said John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif, project manager for the rovers. With the improved energy supplies, both rovers are back on schedule to communicate daily. Opportunity had previously been conserving energy by going three or four days between communications.
No new storms have been lifting dust into the air near either solar-powered rover in the past two weeks. Skies are gradually brightening above both Spirit and Opportunity. "The clearing could take months," said rover Project Scientist Bruce Banerdt. "There is a lot of very fine material suspended high in the atmosphere."
As that material does settle out of the air, the powdery dust is accumulating on surfaces such as the rovers' solar panels and instruments. More dust on the solar panels lessens the panels' capacity for converting sunlight to electricity, even while more sunlight is getting through the clearer atmosphere.
Opportunity's daily supply of electricity from its solar panels reached nearly 300 watt-hours on Aug. 23. That is more than twice as much as five weeks ago, but still less than half as much as two months ago. It is enough to run a 100-watt bulb for three hours.
One reason the rover team chose to drive Opportunity closer to the crater rim was to be prepared, if the pace of dust accumulation on the solar panels increases, to drive onto the inner slope of the crater. This would give the rover a sun-facing tilt to maximize daily energy supplies. The drive was also designed to check performance of the rover's mobility system, so it included a turn in place and a short drive backwards.
The next day, a favorable wind removed some dust from Opportunity's solar panels, providing a boost of about 10 percent in electric output. This forestalled the need to hurry to a sun-facing slope. The team is still excited to get Opportunity inside Victoria Crater to examine science targets on the inner slope that were identified in June, shortly before dust storms curtailed rover activities. An estimate of how soon Opportunity will enter the crater will depend on assessments in coming days of how dust may be affecting the instruments and of how much energy will be available.
On Spirit, dust on the lens of the microscopic imager has slightly reduced image quality for that instrument, although image calibration can compensate for most of the contamination effects. The team is experimenting with ways to try dislodging the dust on the lens. Spirit's solar arrays are producing about 300 watt hours per day as dust accumulation on them offsets clearing skies. Spirit drove 42 centimeters (17 inches) backwards on Aug. 23 to get in position for taking images of a rock that it had examined with its Moessbauer spectrometer. The rover team is planning additional drives for Spirit to climb onto a platform informally named "Home Plate."
Note: This story has been adapted from a news release issued by NASA/Jet Propulsion Laboratory.

Fausto Intilla

www.oloscience.com

Pioneering NASA Spacecraft Mark Thirty Years Of Flight

Source:

http://www.sciencedaily.com/releases/2007/08/070829170339.htm

Science Daily — NASA's two venerable Voyager spacecraft are celebrating three decades of flight as they head toward interstellar space. Their ongoing odysseys mark an unprecedented and historic accomplishment.

Voyager 2 launched on Aug. 20, 1977, and Voyager 1 launched on Sept. 5, 1977. They continue to return information from distances more than three times farther away than Pluto.
"The Voyager mission is a legend in the annals of space exploration. It opened our eyes to the scientific richness of the outer solar system, and it has pioneered the deepest exploration of the sun's domain ever conducted," said Alan Stern, associate administrator for NASA's Science Mission Directorate, Washington. "It's a testament to Voyager's designers, builders and operators that both spacecraft continue to deliver important findings more than 25 years after their primary mission to Jupiter and Saturn concluded."
During their first dozen years of flight, the Voyagers made detailed explorations of Jupiter, Saturn, and their moons, and conducted the first explorations of Uranus and Neptune. The Voyagers returned never-before-seen images and scientific data, making fundamental discoveries about the outer planets and their moons. The spacecraft revealed Jupiter's turbulent atmosphere, which includes dozens of interacting hurricane-like storm systems, and erupting volcanoes on Jupiter's moon Io. They also showed waves and fine structure in Saturn's icy rings from the tugs of nearby moons.
For the past 18 years, the twin Voyagers have been probing the sun's outer heliosphere and its boundary with interstellar space. Both Voyagers remain healthy and are returning scientific data 30 years after their launches.
Voyager 1 currently is the farthest human-made object, traveling at a distance from the sun of about 15.5 billion kilometers (9.7 billion miles). Voyager 2 is about 12.5 billion kilometers (7.8 billion miles) from the sun. Originally designed as a four-year mission to Jupiter and Saturn, the Voyager tours were extended because of their successful achievements and a rare planetary alignment. The two-planet mission eventually became a four-planet grand tour. After completing that extended mission, the two spacecraft began the task of exploring the outer heliosphere.
"The Voyager mission has opened up our solar system in a way not possible before the Space Age," said Edward Stone, Voyager project scientist at the California Institute of Technology, Pasadena, Calif. "It revealed our neighbors in the outer solar system and showed us how much there is to learn and how diverse the bodies are that share the solar system with our own planet Earth."
In December 2004, Voyager 1 began crossing the solar system's final frontier. Called the heliosheath, this turbulent area, approximately 14 billion kilometers (8.7 billion miles) from the sun, is where the solar wind slows as it crashes into the thin gas that fills the space between stars. Voyager 2 could reach this boundary later this year, putting both Voyagers on their final leg toward interstellar space.
Each spacecraft carries five fully functioning science instruments that study the solar wind, energetic particles, magnetic fields and radio waves as they cruise through this unexplored region of deep space. The spacecraft are too far from the sun to use solar power. They run on less than 300 watts, the amount of power needed to light up a bright light bulb. Their long-lived radioisotope thermoelectric generators provide the power.
"The continued operation of these spacecraft and the flow of data to the scientists is a testament to the skills and dedication of the small operations team," said Ed Massey, Voyager project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. Massey oversees a team of nearly a dozen people in the day-to-day Voyager spacecraft operations.
The Voyagers call home via NASA's Deep Space Network, a system of antennas around the world. The spacecraft are so distant that commands from Earth, traveling at light speed, take 14 hours one-way to reach Voyager 1 and 12 hours to reach Voyager 2. Each Voyager logs approximately 1 million miles per day.
Each of the Voyagers carries a golden record that is a time capsule with greetings, images and sounds from Earth. The records also have directions on how to find Earth if the spacecraft is recovered by something or someone.
NASA's latest outer planet exploration mission is New Horizons, which is now well past Jupiter and headed for a historic exploration of the Pluto system in July 2015.
For a complete listing of Voyager discoveries and mission information, visit the Internet at:
http://www.nasa.gov/voyager and http://voyager.jpl.nasa.gov/
JPL manages the Voyager mission for NASA's Science Mission Directorate. NASA's Lewis Research Center (now Glenn Research Center) in Cleveland, Ohio, managed the launches of the Voyager spacecraft.
Note: This story has been adapted from a news release issued by NASA/Jet Propulsion Laboratory.

Fausto Intilla

www.oloscience.com

Supersonic 'Rain' Falls On Newborn Star

Source:

http://www.sciencedaily.com/releases/2007/08/070829143703.htm

Science Daily — Astronomers at the University of Rochester have discovered five Earth-oceans' worth of water that has recently fallen into the planet-forming region around an extremely young, developing star.

Dan Watson, professor of physics and astronomy at the University of Rochester, believes he and his colleagues are the first to see a short-lived stage of protoplanetary disk formation, and the manner in which a planetary system's supply of water arrives from the natal envelope within which its parent star originally formed.
The findings, published in Nature, are the first-ever glimpse of material directly feeding a protoplanetary disk.
The embryonic star in question, called IRAS 4B, lies in a picturesque nebula called NGC 1333, about 1000 light years from Earth. It is one of an initial list of 30 of the youngest "protostars" known, which Watson and his team examined with the Spitzer Space Telescope's infrared spectrograph for signs of very dense, warm material at their cores. It is also the only one of the thirty to show signs of such material, signaled by the infrared spectrum of water vapor.
The watery characteristics of IRAS4B's infrared spectrum can best be explained by material falling from the protostar's envelope onto a surrounding, dense disk. This setup, called by astronomers a "disk-accretion shock," is the formative mechanism of the disks within which all planetary systems are thought to originate.
"Icy material from the envelope is in free-fall, reaching supersonic speeds and crashing into the protoplanetary disk." says Watson. "The ice vaporizes on impact, and the warm water vapor emits a distinctive spectrum of infrared light. That light is what we measured. From the details of the measured spectrum we can tease out the physical details of this brand-new, pre-planetary disk"
Among the details derived so far are the rate of "rainfall" onto the disk – about 23 Earth masses per year – and the characteristics of the "puddle" on the disk's surface: The surface is 170 degrees Kelvin (153 degrees below zero Fahrenheit), and at that temperature there is about an Earth's mass worth of material, including enough water to fill Earth's oceans about five times. The area of the "puddle" is such that, if circular and centered on the Sun, its perimeter would be just beyond the orbit of Pluto. Results such as this will help astronomers assess the early planet-forming potential of IRAS4B's disk, and by inference learn about the earliest stages of our solar system's life.
There are astro-chemical implications of the observations as well. "There are lots of primitive icy bodies in our solar system, and the ice they carry is often thought to descend directly from the interstellar medium, so that by studying one we could learn about the other," says Watson. "But in NGC 1333 IRAS 4B's disk, it is clear that the water is received as vapor and will be re-frozen under different conditions, and this means that the oxygen and hydrogen chemistry of its disk is reset from interstellar conditions. It's not getting pristine, interstellar ice."
Astronomers at the University of Rochester, including Watson and co-author professor William Forrest, helped design the "eyes" of Spitzer specifically to look for objects like IRAS4B and its water because such objects sit in an astronomer's blind spot. Called "Class Zero Protostars" for their extreme youth, these objects radiate substantial light only at long infrared wavelengths, which our atmosphere inconveniently blocks from ground-based telescopes.
When Watson and his team first planned their Spitzer observations, only 50 class-zero protostars were known, and the team selected the 30 brightest. But Watson says that's just the beginning. Astronomers now know of hundreds of such objects, and Watson expects to have thousands to investigate in the coming years.
Another characteristic makes the otherwise un-noteworthy IRAS4B a rarity. It is oriented with its axis pointed almost directly at Earth, splaying out its entire disk to our view and simplifying the process of plumbing its secrets. Only a small fraction of the future candidates are expected be similarly oriented, keeping the search for lots more "raining protostars" a challenge.
This work was supported in part by NASA through the Spitzer-IRS Instrument Team, Origins and Astrobiology programs, and by the National Science and Technology Council of Mexico.
Note: This story has been adapted from a news release issued by University of Rochester.

Fausto Intilla

www.oloscience.com

Mars Reconnaissance Orbiter's Camera Returns More Than 3,000 Images

Source:

http://www.sciencedaily.com/releases/2007/08/070829165453.htm

Science Daily — Diagnostic tests and months of stable, successful operation have resolved concerns raised early this year about long-term prospects for the powerful telescopic camera on NASA's Mars Reconnaissance Orbiter.

The High Resolution Imaging Science Experiment (HiRISE) camera on the orbiter has now taken more than 3,000 images of Mars, resolving features as small as a desk in targeted areas covering thousands of square miles of the Martian surface. Already, this is the largest Mars data set ever acquired by a single experiment. The camera is one of six instruments on the orbiter.
During the first three months after the orbiter's primary science phase began in November, researchers saw an increase in noise and pixel dropouts in data from seven of the camera's 14 detectors. The effects on image quality were small in all but two detectors, but the trend raised concerns noted in a Feb. 7 news release .
Tests have yielded an explanation for the earlier pattern, and the camera's performance record shows the noise stopped getting worse after about three to four months of the science phase.
Alfred McEwen of the University of Arizona, Tucson, principal investigator for the camera, said, "I'm happy to report that there has been no detectable degradation over the past five months."
A team at Ball Aerospace & Technologies Corp., Boulder, Colo., designer and builder of the instrument, has used an engineering model of the camera's focal-plane system to successfully duplicate the problem. This has helped in understanding causes and in testing a procedure for warming the focal-plane electronics prior to each image. One cause is that an electrical interface lacked extra capability beyond minimum requirements. Another cause is an unexpected change in performance of another electronic component over the course of the first thousand or so large images. With pre-warming, the camera acquires good data from all detectors, though minor noise remains an issue in data from one of two channels of one detector collecting infrared imagery.
McEwen said, "Given the stability we've seen and understanding the nature of the problem, we now expect HiRISE to return high-quality data for years to come."
Images from the High Resolution Imaging Science Experiment are online at http://hirise.lpl.arizona.edu/ .
The Mars Reconnaissance Orbiter mission is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, Colo., is the prime contractor and built the spacecraft.
Additional information about the Mars Reconnaissance Orbiter is online at http://www.nasa.gov/mro .
Note: This story has been adapted from a news release issued by NASA/Jet Propulsion Laboratory.

Fausto Intilla

www.oloscience.com

Could Enceladus's Icy Plumes Pose A Hazard To Cassini?

Source:

http://www.sciencedaily.com/releases/2007/08/070824132240.htm

Science Daily — On 12th March 2008, Cassini will swing by Saturn's moon Enceladus at an altitude of less than 100 kilometres at the point of closest approach. This will give scientists and unprecedented opportunity to study the plumes of water vapour emanating from the "tiger stripe" fissures near the moon's south pole, but it has also given the Cassini team pause for thought as to whether ice grains lofted by the jets could damage the spacecraft.

Dr Larry Esposito, who is presenting results of a study at the second European Planetary Science Congress in Potsdam on Thursday 23rd August, said, "These plumes were only discovered two years ago and we are just beginning to understand the mechanisms that cause them. A grain of ice or dust less than two millimetres across could cause significant damage to the Cassini spacecraft if it impacted with a sensitive area. We have used measurements taken with Cassini's UVIS instrument during a flyby of Enceladus in 2005 to try and understand the shape and density of the plumes and the processes that are causing them."
Cassini's UVIS instrument was used to measure how much light from a star was absorbed when the star was obscured by the plumes, and this data used to calculate the amount of water vapour present in the column. Dr Esposito, who leads the UVIS instrument team, and colleagues at the University of Colorado developed simulations of the speeds and densities of particles in the plumes, based on emissions from multiple jets along each tiger stripe.
By comparing the results to the UVIS observations, they were able to calculate the average size of particles at the point where the plumes will be most dense during Cassini's March '08 encounter. Dr Esposito said, "Our results indicated that the average sized particle in the plume was less than a thousandth of the size that would cause damage, but we still needed to find out if high-pressure vents could send larger particles into the mix."
For a dangerous particle to be lofted by the plume, the mass of the particle must be equalled by the mass of the supporting column of water vapour. Dr Esposito has used two independent searches of the plumes, which could spot jets just 50 metres across with opacity of 10 percent.
Dr Esposito said, "In both these searches, we have seen no evidence for high-pressure jets. We estimate that the chance of Cassini being hit by a dangerously large particle appears to be no more than one in five hundred. Better measurements of the size distribution and its opacity would improve the model, but we think this is a conservative estimate. The chances are that Cassini should be unharmed by the flyby."
Note: This story has been adapted from a news release issued by European Planetology Network.

Fausto Intilla

www.oloscience.com

Space-time Distorts Near Neutron Stars As Einstein Predicted

Source:

http://www.sciencedaily.com/releases/2007/08/070827112825.htm

Science Daily — Using European and Japanese/NASA X-ray satellites, astronomers have seen Einstein’s predicted distortion of space-time around three neutron stars, and in doing so they have pioneered a groundbreaking technique for determining the properties of these ultradense objects.

Neutron stars contain the most dense observable matter in the universe. They cram more than a sun’s worth of material into a city-sized sphere, meaning a few cups of neutron-star stuff would outweigh Mount Everest. Astronomers use these collapsed stars as natural laboratories to study how tightly matter can be crammed under the most extreme pressures that nature can offer.
"This is fundamental physics," says Sudip Bhattacharyya of NASA’s Goddard Space Flight Center in Greenbelt, Md. and the University of Maryland, College Park. "There could be exotic kinds of particles or states of matter, such as quark matter, in the centers of neutron stars, but it’s impossible to create them in the lab. The only way to find out is to understand neutron stars."
To address this mystery, scientists must accurately and precisely measure the diameters and masses of neutron stars. In two concurrent studies, one with the European Space Agency’s XMM-Newton X-ray Observatory and the other with the Japanese/NASA Suzaku X-ray observatory, astronomers have taken a big step forward.
Using XMM-Newton, Bhattacharyya and his NASA Goddard colleague Tod Strohmayer observed a binary system known as Serpens X-1, which contains a neutron star and a stellar companion. They studied a spectral line from hot iron atoms that are whirling around in a disk just beyond the neutron star’s surface at 40 percent the speed of light.
Previous X-ray observatories detected iron lines around neutron stars, but they lacked the sensitivity to measure the shapes of the lines in detail. Thanks to XMM-Newton’s large mirrors, Bhattacharyya and Strohmayer found that the iron line is broadened asymmetrically by the gas’s extreme velocity, which smears and distorts the line because of the Doppler effect and beaming effects predicted by Einstein’s special theory of relativity. The warping of space-time by the neutron star’s powerful gravity, an effect of Einstein’s general theory of relativity, shifts the neutron star’s iron line to longer wavelengths.
"We've seen these asymmetric lines from many black holes, but this is the first confirmation that neutron stars can produce them as well. It shows that the way neutron stars accrete matter is not very different from that of black holes, and it gives us a new tool to probe Einstein’s theory," says Strohmayer.
A group led by Edward Cackett and Jon Miller of the University of Michigan, which includes Bhattacharyya and Strohmayer, used Suzaku’s superb spectral capabilities to survey three neutron-star binaries: Serpens X-1, GX 349+2, and 4U 1820-30. This team observed a nearly identical iron line in Serpens X-1, confirming the XMM-Newton result. It detected similarly skewed iron lines in the other two systems as well.
"We’re seeing the gas whipping around just outside the neutron star’s surface," says Cackett. "And since the inner part of the disk obviously can’t orbit any closer than the neutron star’s surface, these measurements give us a maximum size of the neutron star’s diameter. The neutron stars can be no larger than 18 to 20.5 miles across, results that agree with other types of measurements."
"Now that we’ve seen this relativistic iron line around three neutron stars, we have established a new technique," adds Miller. "It’s very difficult to measure the mass and diameter of a neutron star, so we need several techniques to work together to achieve that goal."
Knowing a neutron star’s size and mass allows physicists to describe the "stiffness," or "equation of state," of matter packed inside these incredibly dense objects. Besides using these iron lines to test Einstein’s general theory of relativity, astronomers can probe conditions in the inner part of a neutron star’s accretion disk.
The XMM-Newton paper appeared in the August 1 Astrophysical Journal Letters. The Suzaku paper has been submitted for publication in the same journal.
Note: This story has been adapted from a news release issued by NASA/Goddard Space Flight Center.

Fausto Intilla

www.oloscience.com

Flares From Sun's Far Side May Affect Space Weather Of Inner Planets

Source:

http://www.sciencedaily.com/releases/2007/08/070824131445.htm

Science Daily — Observations of solar flares by spacecraft at Mars, Venus and the Earth show that eruptions on the far side of the Sun may affect our "space weather" back on Earth.

In December 2006, a series of solar flares produced in a single active region were observed from three different points, each approximately 120 degrees apart. The results of these observations are now presented at the European Planetary Sciences Congress, Potsdam, on Thursday 23rd August by a team of scientists from the Swedish Institute of Space Physics.
Although solar flares and solar energetic particles (SEP) have been reported many times based on Earth-orbiting satellites or other planetary spacecraft, this time scientists achieved simultaneous plasma observations using instruments aboard Mars Express, Venus Express , the SOHO solar orbiter and a GOES environmental satellite, which is in geostationary orbit around the Earth.
"These observations indicate that flare activities on the far side of the Sun may affect terrestrial space weather as a result of travelling more than 90° in both azimuthal directions in the heliosphere", said Dr Yoshifumi Futaana, one of the investigators in this study.
Another important consequence of the analysis of SEP events is the insight they can provide into the process of planetary atmospheric evolution.
During the December 2006 event, Mars Express observed an enhancement of ion (oxygen) outflow flux from the Martian atmosphere. This is the first observation of this kind and suggests that the solar extreme ultraviolet flux levels significantly affect the atmospheric loss from unmagnetized planets.
Dr Futaana explained, "This is of interest for planetary scientists because the ion outflow should play an important role on the evolution of planetary atmosphere if the flux is integrated over a geological time scale (billions of years)."
This violent solar flare event also gives us a hint to solve a mystery of missing water on Mars. Mars is believed to have possessed a large amount of water approximately 3.5-4.0 billion years ago. However, no one knows where the water has gone now. One plausible idea is that the water has escaped to space, in the evolution of the planet’s atmosphere. One of the main scientific aims of Mars Express is to measure exactly how much of this water has been lost to space.
Note: This story has been adapted from a news release issued by European Planetology Network.

Fausto Intilla

www.oloscience.com

Amateur Astronomers Help Professionals Unveil The Atmosphere Of Venus

Source:

http://www.sciencedaily.com/releases/2007/08/070824120456.htm

Science Daily — Results from an ongoing collaboration between amateur astronomers and the European Space Agency to support the Venus Express mission will be presented at the European Planetary Science Congress in Potsdam on Wednesday 22nd August.

Silvia Kowollik, from the Zollern-Alb Observatory in Germany and one of the participants in the project, said, "This is the first time there’s been a European collaboration between amateur astronomers and scientists. In the United States, they have a long tradition and a lot of experience in this kind of work. In Europe we are just starting."
Since its launch in 2006, ESA’s Venus Amateur Observing Project (VAOP) has invited amateur astronomers to submit scientifically useful images and data to support scientists working on the Venus Express mission. The amateur images, taken in the infrared, visible and ultraviolet bands, give a different, global perspective on features observed by the spacecraft, show a comparative view of the planet in various parts of the spectrum covered by instruments aboard Venus Express, and can also capture views of Venus that are hidden to the spacecraft in its orbit. The highly elliptical orbit of Venus Express means that the spacecraft moves slowly around the planet’s south pole but whips over the northern latitudes, so the ground-based images are especially important for observing features north of the equator.
Dr Thomas Widemann, who is participating in a parallel professional campaign of ground-based observations to support Venus Express said, "There have been huge advances in relatively cheaply available equipment, which means that amateurs can take images in wavelengths from infrared through to ultraviolet with impressive accuracy and content. These amateur observations are the last link in a chain that starts with Venus Express and continues with the professional ground-based activities. When joined together, all these observations will all help to peel back the atmosphere of Venus and reveal her mysteries."
Developments in video astronomy have meant that amateurs can select and combine thousands of rapidly exposed video frames in order to cancel out the distorting effects of atmospheric turbulence.
Ms Kowollik said, "This has been a great experience for amateurs. Several observers in Germany have taken part and have gained considerable expertise in image processing. We are now looking forward to future Venus observation campaigns."
The ultraviolet observations are of particular interest because scientists still do not know the chemical constituent of Venus’s atmosphere that causes the planet’s yellowish tinge. Dr Widemann said, "Something is absorbing the blue end of the visible spectrum. There are many theories – it could be material derived from meteorites that contains iron, it could be molecules of carbon monoxide dissolved in sulphuric acid droplets, or molecules made of several sulphur atoms. Perhaps it’s a combination of all of these. The amateur ultraviolet observations may assist in this investigation. To know for sure, we need measurements taken within the Venusian atmosphere, perhaps by instruments carried by a balloon."
"The next ground-based observing campaign will begin in September, when Venus increases its angular distance to the Sun in the morning sky", Dr Widemann said, "By participating in the VAOP, amateurs can receive proper recognition for their skill from the professional community. It should be a great boost for amateurs across Europe and will give them a just reward for their enthusiasm.
Note: This story has been adapted from a news release issued by European Planetology Network.

Fausto Intilla

www.oloscience.com

Discovering Distant Galaxies: HAWK-I Takes Off

Source:

http://www.sciencedaily.com/releases/2007/08/070823094814.htm

Science Daily — Europe's flagship ground-based astronomical facility, the ESO VLT, has been equipped with a new 'eye' to study the Universe. Working in the near-infrared, the new instrument - dubbed HAWK-I - covers about 1/10th the area of the Full Moon in a single exposure. It is uniquely suited to the discovery and study of faint objects, such as distant galaxies or small stars and planets.

After three years of hard work, HAWK-I (High Acuity, Wide field K-band Imaging) saw First Light on Yepun, Unit Telescope number 4 of ESO's VLT, on the night of 31 July to 1 August 2007. The first images obtained impressively demonstrate its potential.
"HAWK-I is a credit to the instrument team at ESO who designed, built and commissioned it," said Catherine Cesarsky, ESO's Director General. "No doubt, HAWK-I will allow rapid progress in very diverse areas of modern astronomy by filling a niche of wide-field, well-sampled near-infrared imagers on 8-m class telescopes."
"It's wonderful; the instrument's performance has been terrific," declared Jeff Pirard, the HAWK-I Project Manager. "We could not have hoped for a better start, and look forward to scientifically exciting and beautiful images in the years to come."
During this first commissioning period all instrument functions were checked, confirming that the instrument performance is at the level expected. Different astronomical objects were observed to test different characteristics of the instrument. For example, during one period of good atmospheric stability, images were taken towards the central bulge of our Galaxy. Many thousands of stars were visible over the field and allowed the astronomers to obtain stellar images only 3.4 pixels (0.34 arcsecond) wide, uniformly over the whole field of view, confirming the excellent optical quality of HAWK-I.
HAWK-I takes images in the 0.9 to 2.5 micron domain over a large field-of-view of 7.5 x 7.5 arcminutes. This is nine times larger than that of ISAAC, another near-infrared imager on the VLT that went into operation in late 1998. ISAAC has shown how deep near-infrared images can contribute uniquely to the discovery and study of large, distant galaxies, and to the study of discs around stars or even very low mass objects, down to a few Jupiter masses.
HAWK-I will build on this experience by being able to study much larger areas with an excellent image quality. HAWK-I has four 2k x 2k array detectors, i.e. a total of 16 million 0.1 arcsecond pixels.
"Until the availability of the James Webb Space Telescope in the next decade, it is clear that 8-m class telescopes will provide the best sensitivity achievable in the near-infrared below 3 microns," explained Mark Casali, the ESO scientist responsible for the instrument.
Given the wide field, fine sampling and the high sensitivity of HAWK-I, the deepest scientific impact is expected in the areas of faint sources. "With its special filter set, HAWK-I will allow us to peer into the most distant Universe," said Markus Kissler-Patig, the Instrument Scientist. "In particular, with HAWK-I, we will scrutinise the very first objects that formed in the Universe."
HAWK-I will also be very well suited for the search for the most massive stars and for the least massive objects in our Galaxy, such as hot Jupiters. But HAWK-I will also be a perfect instrument for the study of outer Solar System bodies, such as distant, icy asteroids and comets. HAWK-I is the eleventh instrument to be installed at ESO's VLT. It bridges the gap between the first and the second generation instruments to be installed on this unique facility.
Note: This story has been adapted from a news release issued by ESO.

Fausto Intilla

www.oloscience.com

Hinode Helps Unravel Long-standing Solar Mysteries

Source:

http://www.sciencedaily.com/releases/2007/08/070822084643.htm

Science Daily — A year after launch, scientists working with Hinode, a Japanese mission with ESA participation, are meeting at Trinity College, Dublin, to discuss latest findings on solar mysteries - including new insights on solar flares and coronal heating.

Highlights include new insights on the workings of solar flares and on the mechanism behind coronal heating.
Hinode (Sunrise in Japanese) was launched to study magnetic fields on the Sun and their role in powering the solar atmosphere and driving solar eruptions. With its Extreme Ultraviolet Imaging Spectrometer (EIS), effectively a solar speed camera, it is now possible to pinpoint the source of eruptions during solar flares and to find new clues about the heating processes of the corona.
The speed camera is a spectrometer, an instrument that splits the light coming from solar plasma, a tenuous and highly variable gas, into its distinct colours (or spectral lines), providing detailed information about the plasma. The velocity of the gases in a solar feature is measured by the Doppler effect - the same effect that is used by police radars to detect speeding motorists.
“Hinode is an impressive example of international cooperation and is now helping us solve the mysteries of the Sun with spectacular new data,” says Bernhard Fleck, ESA’s Hinode and SOHO project scientist.
Keith Mason, of the Science and Technology Facilities Council (STFC) said, “Our Sun is a dynamic and violent entity and European astronomers have played a crucial role in understanding it; right from the first observation of a solar flare to present-day work to predict and protect against the Sun’s outbursts.”
Solar flares, massive energetic explosions that rise up from the Sun, can damage manmade satellites and pose a radiation hazard to astronauts. Despite decades of study, many aspects of this phenomenon are not well-understood. Hinode’s observations are now shedding light on possible mechanisms that accelerate solar particles in flares.
Louise Harra at the Mullard Space Science Laboratory, University College London, leading the EIS team says, “We knew that solar flares can impact a vast area on the Sun, sometimes leaving behind mysterious ‘dark patches’. Using Hinode, for the first time we have been able to train a speed camera on the material in these dark areas – which can be twenty times the diameter of the Earth."
"We have witnessed material flowing from the dark patch in the wake of the flare, feeding the particle flow that can be hazardous for anything in its path as it hurtles through space at 2000 times the speed of a fighter plane.”
These dark areas fade away after the flare, over several days. “In the long term, understanding solar storms in this new level of detail will allow us to make better predictions of ‘space weather’ storms. This is critical for satellite telecommunications, which we now take for granted”, she adds.
Ichiro Nakatani, JAXA Project Manager for Hinode commented, “We are delighted that nearly a year after launch, we are discovering new things about our nearest star, with many more discoveries to come. The years of hard work that went into developing the satellite were definitely worth it.”
Note: This story has been adapted from a news release issued by European Space Agency.

Fausto Intilla

www.oloscience.com

Saturn's Skewed Ring Current

Source:

http://www.sciencedaily.com/releases/2007/08/070824130101.htm

Science Daily — Images taken by Cassini’s Magnetospheric Imaging Instrument (MIMI) show that Saturn’s ring current is a warped disc that balloons out of the equatorial plane on the planet’s dayside and remains a thin disk that rises above the plane at larger distances on the nightside.

Dr Stamatios "Tom" Krimigis, the Principal Investigator for the instrument, who is presenting images at the European Planetary Science Congress in Potsdam on Thursday 23rd August, said, "Ring currents surround planets sort of like the brim of a hat.
Uniquely in Saturn’s case, that brim has been crushed at the front and tipped up at the back, so it’s pretty bent out of shape!"
The presence of a ring current around Saturn was first suggested in the early 1980s following magnetic anomalies observed by the Pioneer 11 and Voyager 1 and 2 spacecraft. Ring currents are also found around Earth and Jupiter. They are caused when plasma becomes trapped between mirror points on magnetic field lines, similar to the Van Allen radiation belts surrounding Earth, and gradually drifts around the planet. The aggregate motion of all of the hot ions distributed around the equator generates an electric current.
On Saturn, the source of the plasma is material from the rings and gas vented by geysers on the moon Enceladus, which is subsequently ionized and accelerated. The MIMI images show that the ring current occupies a region of the equatorial plane between 540 000 kilometres and 1 080 000 kilometres from the centre of Saturn. They also show that Saturn’s ring current is persistently asymmetric (unlike Earth’s), and that the asymmetry rotates nearly rigidly with Saturn.
MIMI, which was developed by an international team led by the Johns Hopkins University Applied Physics Laboratory (APL), Laurel, Maryland, has three distinct sensors that allow it to "visualize the invisible" and show the plasma and radiation belts in Saturn’s environment in an image. The MIMI instrument includes an Ion and Neutral Camera developed by APL, a spectrometer built by the University of Maryland, and a low energy particle detector developed by the Max-Planck-Institut fuer Sonnensystemforschung and a number of co-investigator institutions including CESR in Toulouse.
Ring currents
A ring current at Earth was proposed by Chapman and Ferraro in the 1930s to explain the decrease in the equatorial magnetic field during geomagnetic storms; the detailed nature in terms of composition and energy content was not determined until the mid-eighties by the Active Magnetospheric Particle Tracer Explorers (AMPTE) mission, a joint programme by the US, Germany and the UK. The Principal Investigator for the AMPTE mission was Dr Krimigis.
In the case of Earth, ionospheric sources dominate the formation of the ring current.
Jupiter’s ring current was first measured partially by Voyager. The Galileo mission to Jupiter added considerably to the understanding of Jupiter’s ring current, showing thatat Jupiter, Io’s volcanoes provide the gas that is subsequently ionized and accelerated
Note: This story has been adapted from a news release issued by European Planetology Network.

Fausto Intilla

www.oloscience.com

The Highs And Lows Of Martian Water Vapour

Source:

http://www.sciencedaily.com/releases/2007/08/070824132747.htm

Science Daily — Recent observations by instruments aboard Mars Express show peculiar behaviour by water vapour in the highest and lowest regions of Mars.

Measurements of water vapour in the atmosphere of Mars by the PFS (Planetary Fourier Spectrometer) and OMEGA (Observatoire pour la Minéralogie, l’Eau, les Glaces, at l’Activité) instruments, both onboard Mars Express, give us a clear view on the seasonal behaviour of water vapour in the atmosphere of Mars. The study shows irregularities in the behaviour of water vapour, different from the global trend on Mars, in the atmosphere surrounding the Big Volcanoes and the Hellas Basin, which are respectively the highest and lowest regions on Mars.
There have been regular measurements of the behaviour of water vapour during the Martian year since the 1970s, but the complementary characteristics of these two instruments allow a comprehensive analysis of the Martian water cycle with unprecedented detail.
"For most of the year, the atmosphere on the summit of the big volcanoes is enriched in water vapour – the ratio of water vapour is much higher compared to the surrounding areas. This can be explained by upslope currents activated by the extreme topography of the region that bring up a lot of material, water vapour included, from the bottom to the summit," said Luca Maltagliati, a scientist at the Max Planck Institute for Solar System Research.
In the Hellas Basin region, the observations also showed a peculiar seasonal behaviour. While the north seems to present the same quantity of water vapour through the Martian year, the interior of the basin seems to be depleted of it in some seasons, especially if compared to the south region.
The causes for this are still being investigated but it is believed that, in this case, local circulation of the atmosphere plays an important role. In fact, Hellas itself is known to have an important part in driving the circulation of the whole Southern hemisphere of Mars. The presence of surface ice was also observed during local winter.
Results from the study will be presented by Luca Maltagliati at the European Planetary Science Congress in Potsdam on Wednesday 22nd August.
These results mark the importance of local influence on the global water cycle.
Mars Express
Mars Express is the European Space Agency's first mission to Mars. The spacecraft, which has been in orbit since December 2003, is investigating the history of water on Mars and mapping the planet in unprecedented detail.
Big Volcanoes on Mars
Tharsis Montes is a range of three volcanoes in the Tharsis region of Mars.
It consists of Ascraeus Mons (whose summit is about 18 km above Mars' mean surface level, and is 460 km in diameter), Pavonis Mons (14 km above Mars'
mean surface level) and Arsia Mons (almost 19 km high and 435 km in diameter). Another volcano, Olympus Mons (22 km high and 600km in diameter), is the tallest known mountain in the Solar System and is located northwest of the Tharsis volcanoes.
The Hellas Impact Basin
The Hellas Impact Basin, also known as the Hellas Planitia is a roughly circular impact crater located in the southern hemisphere of the planet Mars. It is the largest impact structure on the planet, with a diameter of about 2,300 km and a depth of 8 km in its lowest point) The basin is thought to have been formed during the Late Heavy Bombardment period of the Solar System, over 3.9 billion years ago, when a large asteroid impacted Mars.
Note: This story has been adapted from a news release issued by European Planetology Network.

Fausto Intilla

www.oloscience.com

Jupiter: Friend Or Foe?

Source:

http://www.sciencedaily.com/releases/2007/08/070824133636.htm

Science Daily — The traditional belief that Jupiter acts as a celestial shield, deflecting asteroids and comets away from the inner Solar System, has been challenged by the first in a series of studies evaluating the impact risk to the Earth posed by different groups of object.

On Friday 24th August at the European Planetary Science Congress in Potsdam, Dr Jonathan Horner presented a study of the impact hazard posed to Earth by the Centaurs, the parent population of the Jupiter Family of comets (JFCs). The results show that the presence of a Jupiter-like planet in the Solar System does not necessarily lead to a lower impact rate at the Earth.
Dr Horner, from the UK's Open University (OU), said, "The idea that a Jupiter-like planet plays an important role in lessening the impact risk on potentially habitable planets is a common belief but there has only really been one study done on this in the past, which looked at the hazard due to the Long Period Comets. We are carrying out an ongoing series of studies of the impact risks in planetary systems, starting off by looking at our own Solar System, since we know the most about it!"
The team at the OU developed a computer model that could track the paths of 100,000 Centaurs around the Solar System over 10 million years. The simulation was run five times: once with Jupiter at its current mass, once without a Jupiter, and then with planets of three-quarters, a half and a quarter the mass of Jupiter (for comparison, Saturn is about a third of the mass of Jupiter). The team found that the impact rate in a Solar System with a planet like our Jupiter is about comparable to the case where there is no Jupiter at all. However, when the mass of Jupiter was between these two extremes, the Earth suffered an increased number of impacts from the JFCs.
Dr Horner said, "We've found that if a planet about the mass of Saturn or a bit larger occupied Jupiter's place, then the number of impacts on Earth would increase. However if nothing was there at all, there wouldn't be any difference from our current impact rate. Rather than it being a clear cut case that Jupiter acts as a shield, it seems that Jupiter almost gives with one hand and takes away with the other!"
The study shows that if there is no giant planet present, the JFCs will not be diverted onto Earth-crossing orbits, so the impact rate at the Earth is low. A Saturn-mass planet would have the gravitational pull to inject objects onto Earth-crossing orbits, but would not be massive enough to easily eject objects from the Solar System. This means that there would be more objects on Earth-crossing orbits at any given time, and therefore more impacts.
However, a planet with Jupiter's vast mass can give objects the gravitational boost to eject them from the Solar System. Therefore, if Jupiter deflects JFCs to an Earth-crossing orbit, it may well later sweep them right out of the Solar System and off the collision course with the Earth.
The group is now assessing the impact risk posed to the Earth by the Asteroids and will go on to study the Long Period Comets, before examining the role of the position of Jupiter within our system.
Jupiter family of comets
The Jupiter Family of Comets (JFCs) are short period comets with an orbital period of less than 20 years. Their orbits are controlled by Jupiter and they are believed to originate from the Kuiper Belt, a vast population of small icy bodies that orbit just beyond Neptune. Famous JFCs include Comet 81P/Wild 2, which was encountered by the Stardust spacecraft in January 2004 and Comet Shoemaker Levy-9, which broke up and collided with Jupiter in July 1994.
Note: This story has been adapted from a news release issued by European Planetology Network.

Fausto Intilla

www.oloscience.com

Astronomers Baffled By Basalt In The Outer Asteroid Belt

Source:

http://www.sciencedaily.com/releases/2007/08/070824130652.htm

Science Daily — 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 thought 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.
Dr Duffard, of the Instituto de Astrofisica de Andalucia in Spain, and his colleague, Dr Fernando Roig, from the Observatorio Nacional in Rio de Janeiro, Brazil, selected the two asteroids, (7472) Kumakiri and (10537) 1991 RY16, for investigation by from a group of six candidate V-type asteroids identified using photometric data from the Sloan Digital Sky Survey (SDSS).
The reflectance spectra of the two bodies seem to show the characteristics of a V-type asteroid. However, there is a shallow absorption band around the wavelength of red visible light, which has never been observed before in other V-type spectra. This means that these objects have a slightly different chemical composition and do not fit into any existing category of asteroid. The unexpected dip in the spectra could have two sources: it could be due to impacts with other asteroids or comets "shocking" iron-rich compounds into a oxidized state, or it could indicate the presence of olivine, a green mineral that is also known as the semi-precious gemstone.
Dr Duffard said, "We need now to observe both objects in the near-infrared range to confirm whether they have a basaltic surface. If they do, we will need to try and work out where they came from and the fate of their parent objects. If they do not, we will have to come up with a new class of asteroid."
Note: This story has been adapted from a news release issued by European Planetology Network.

Fausto intilla

www.oloscience.com

Martian Life? Small Percentage Of Martian Soil Samples Could Have Biological Origin

Source:

http://www.sciencedaily.com/releases/2007/08/070824122441.htm

Science Daily — 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, Germany, 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.
A 60% solution of hydrogen peroxide has a freezing point of - 56.5 degrees Celsius, and the supercooling properties of such mixtures could mean that metabolic activity could survive at even lower temperatures. In addition, hydrogen peroxide-water solutions tend to attract water, which means that organisms could scavenge water molecules from the Martian atmosphere.
The downside of the water-scavenging biochemistry is that if the organisms were exposed to liquid water or warm atmospheres with high humidity, they could die through over hydration. In this case, the cell would break down, releasing oxygen. Any organic compounds could then react with the hydrogen peroxide, releasing carbon dioxide, water vapour and traces of nitrogen and minor constituents.
Dr Houtkooper said, "This hydrogen peroxide-water hypothesis could provide answers for several aspects of the Viking results that remain unexplained thirty years on. The concept of this type of life is also interesting for planners of future missions searching for life on Mars. With the long timescales involved in planning and launching Mars landers, there is a dire necessity to anticipate what kind of life we should expect to find and where we should be looking. Organisms with the hydrogen peroxide-water biochemistry would be more likely to be active in colder areas on Mars with high water vapour concentrations, as would be expected along the polar ice fringe. Looking further ahead, a sample return mission would mean that we could use all that present technology affords to analyse signs of life.
However, if the organisms were to have the chemistry we are proposing, they may well decompose completely into gases during the journey back to Earth, without leaving even a smudge behind."
The existence of organisms with the hydrogen peroxide-water chemistry would raise interesting questions about the origins of life on Earth. Dr Houtkooper does not think that it would necessarily imply independent origins for terrestrial and Martian life. "A detailed study of the biochemistry and genetics would be needed to determine whether the life forms were related. The transfer of terrestrial organisms to Mars or vice versa is a possibility given favorable conditions for the origin and persistence of life on both planets early in solar system history. The transfer of terrestrial organisms by early spacecrafts to Mars that either landed or crashed is a possibility, but it is not plausible that these organisms evolved in a few years."
Hydrogen peroxide is not unknown in the metabolic processes of terrestrial organisms. The Bombardier beetle, Brachinus Crepitans, uses a 25% solution of hydrogen peroxide to produce a steam explosion in the face of pursuing predators.
Dr Houtkooper said, "There does not appear to be any basic reason why hydrogen peroxide could not be used by living systems. While organisms on Earth have found it advantageous to include salt in their intracellular fluids, hydrogen peroxide may have been more suitable for organisms adapting to the cold, dry environment of Mars."
Background Information
NASA's Viking Mission to Mars was composed of two spacecraft, Viking 1 and Viking 2, each consisting of an orbiter and a lander. TheViking 1 Lander touched down on 20th July 1976, followed by the Viking 2 Lander 3rd September.
Each lander conducted four experiments intended to detect the presence of microbiological life on the Martian surface. Soil samples were retrieved by the landers' extendible arms.
The Gas Exchange Experiment (GEX) looked for changes in the makeup of gases in a test chamber, changes that would indicate biological activity.
The Labeled Release Experiment (LR) was set up to detect the uptake of a radioactively-tagged liquid nutrient by microbes and then analyse gases emitted by any microbes for signs of the tagging.
The Pyrolytic Release Experiment (PR) heated soil samples that had been exposed to radioactively-tagged carbon dioxide to see if the chemical had been used by organisms to make organic compounds.
The Gas Chromatograph -- Mass Spectrometer Experiment (GCMS) heated a soil sample and revealed an unexpected amount of water but failed to detect organic compounds.
Note: This story has been adapted from a news release issued by European Planetology Network.

Fausto Intilla

www.oloscience.com

Astronomers Get First Look At Uranus's Rings As They Swing Edge-on To Earth

Source:

http://www.sciencedaily.com/releases/2007/08/070823141039.htm

Science Daily — As the rings of Uranus swing edge-on to Earth - a short-lived view we get only once every 42 years - astronomers observing the event are getting an unprecedented, glare-free view of the rings and the fine dust that permeates them.

The rings were discovered in 1977, so this is the first opportunity astronomers have had to observe a Uranus ring crossing and perhaps to discover a new moon or two.
While the Keck II telescope and the Hubble Space Telescope have been looking at the planet for years in anticipation of this event, ground-based telescopes in Chile and southern California have targeted the planet during the actual ring crossing.
Based on the Keck observations, a team of astronomers led by Imke de Pater of University of California, Berkeley, reports Thursday, Aug. 23 in Science Express, the online edition of Science magazine, that the rings of micron-sized dust have changed significantly since the Voyager 2 spacecraft photographed the Uranus system 21 years ago. She will discuss the results during a talk August 23 at the European Planetary Science Congress 2007 meeting in Potsdam, Germany.
The inner rings are much more prominent than expected, revealing material in otherwise empty regions of the system of rings.
"People tend to think of the rings as unchanging, but our observations show that not to be the case," said de Pater, a UC Berkeley professor of astronomy. "There are a lot of forces acting on small dust grains, so it is not that crazy to find that the arrangement of rings has changed."
Using the near infrared camera (NIRC2) and adaptive optics on the Keck II telescope on May 28, the team took striking images of the nearly edge-on ring appearing as a bright line bisecting a dim Uranus, which appears dark in the infrared. The observations were conducted during an engineering run by Marcos van Dam, adaptive optics scientist at the W. M. Keck Observatory, after the installation of a new wavefront sensor.
"The improvements to the adaptive optics systems allowed us to capture unbelievably crisp images of Uranus; it was as if the Keck telescope was orbiting in space," said van Dam.
On Aug. 14, the Hubble Space Telescope also imaged the planet very near the moment when the rings were perfectly aligned with Earth, showing similar features but also including some recently-discovered outer rings. The image was released today by the Space Telescope Science Institute.
"The outermost ring is not visible in our infrared images," said de Pater's co-author, Heidi B. Hammel of the Space Science Institute in Boulder, Colo. "This ring is very blue, and therefore harder to see in the infrared. We may detect it when the rings are fully edge-on and when we can observe it for several hours."
With further analysis of the Hubble data, astronomer Mark Showalter of the SETI Institute hopes to detect some of the small moons, and perhaps some not seen before, that shepherd the debris into distinct rings.
"Two little satellites called Cordelia and Ophelia straddle the brightest ring, the epsilon ring, and keep it in place, but people have always assumed there must be a bunch more of these satellites that are confining the nine other narrow rings," Showalter said. "This is the unique viewing geometry that only comes along once in 42 years, when we have a chance of imaging these tiny satellites, because normally they are lost in the glare of the rings. Now, the rings are essentially invisible."
Astronomers at the Very Large Telescope (VLT) in Chile, run by the European Southern Observatory (ESO), and at the Palomar Observatory in southern California operated by the California Institute of Technology, also observed Uranus during the current crossing.
"The VLT took data at the precise moment when the rings were edge-on to Earth," said de Pater, who worked with two team members observing in Chile: Daphne Stam of the Technical University of Delft in the Netherlands and Markus Hartung of ESO. Meanwhile, astronomers Philip Nicholson of Cornell University in New York and Keith Matthews of Caltech observed from atop Mt. Palomar.
Until Voyager flew by in January 1986, the rings were only known from the way they temporarily blocked the light of stars passing behind Uranus. Earth-based images have been too blurry until recently, with the advent of Keck adaptive optics and the Advanced Camera for Surveys of the Hubble telescope. Nevertheless, when the sunlit side of Uranus's rings are in full view of Earth, the densely-packed rings reflect so much light that their glare completely dominates the fainter glow from micron-sized dust.
Earth's orbit around the sun permits three opportunities to view the rings edge-on: Uranus made its first ring crossing as seen from Earth on May 3, it made its second crossing on Aug. 16, and will cross for the third and last time on Feb 20, 2008. Though the last ring crossing relative to Earth will be hidden behind the sun, most of Earth's premier telescopes, including Keck, Hubble, VLT and Palomar, plan to focus on the planet again in the days following Dec. 7.
"December 7 is the Uranian equinox, when the rings are perfectly edge-on to the sun, and after that, there is a brief period again when we will view the dark side of the rings, before they become illuminated again for another 42 years," Hammel said.
The advantage of observations at a ring-plane crossing is that it becomes possible to look at the rings from the shadowed side. From that vantage, the normally-bright outer rings grow fainter because their centimeter- to meter-sized rocks obscure one another, while the dim inner rings get brighter as their material merges into a thin band along the line of sight.
The dust belts that Voyager saw differ radically from today's dust distribution, according to coauthors de Pater and Showalter. Most interesting is a broad, inner ring called zeta, whose position today is several thousand kilometers farther from the planet than when it was discovered by Voyager.
"The ring may have moved, or it may be an entirely new ring," noted Showalter.
Similar, dramatic changes in dust distribution have also been observed recently in Saturn's and Neptune's rings. This is not surprising, because gravity keeps the larger ring particles in orbit, but other smaller forces can nudge the tiny dust grains around, de Pater said. These forces include pressure from sunlight, drag produced as the dust plows through ionized plasma around Uranus, and even drag from the planet's magnetic field.
"Impacts into the larger bodies in the system also could knock dust off and create new rings," de Pater said.
"With further observations, the time scales over which these variations occur should provide new insight into the physical processes at work," the authors concluded.
Support for the Keck observations came from the National Science Foundation, the National Aeronautics and Space Administration, the Keck Observatory and the UC Santa Cruz Technology Center for Adaptive Optics.
Note: This story has been adapted from a news release issued by University of California - Berkeley.

Fausto Intilla

www.oloscience.com

Observations Of Asteroid Itokawa Will Aid In Assessing Risks From Future Asteroids

Source:

http://www.sciencedaily.com/releases/2007/08/070823092953.htm

Science Daily — The space-borne infrared observatory AKARI, observed asteroid Itokawa last month with its Infrared Camera. The data will be used to refine estimates of sizes of potentially hazardous asteroids in the future.

The data collected by AKARI, a JAXA mission with ESA participation, complements that from JAXA’s asteroid explorer Hayabusa in late April this year.
As AKARI observed Itokawa on 26 July it was in the constellation of Scorpius, and was about 19 magnitudes bright in visible light. The asteroid and Earth were closest to each other, at a distance of about 42 million km (for comparison, Earth is 150 million km from the Sun). Given how close it was, Itokawa moved a significant distance on the sky over the short observing time.
Using observational data of asteroids such as Itokawa in combination with data from the explorer, models that estimate asteroid sizes can be made more accurate. This is especially useful for estimating the size of potentially hazardous asteroids which may be discovered in the future.
Before Hayabusa arrived at Itokawa, many observations to determine the asteroid's approximate size had already been attempted. Among the many different methods of measurement, the most accurate estimate was achieved by mid-infrared observations.
With AKARI, it was possible to observe Itokawa at several different wavelengths in the mid-infrared range, obtaining a much more comprehensive set of data. This data is very important, not only for the study of the asteroid’s infrared properties, but also for use as a template and source of comparison with other asteroids, to improve the estimates of their sizes.
Most sunlight falling on Itokawa is absorbed, heating the asteroid up. It then re-emits this energy as bright infrared light, which was in turn observed by AKARI. Only a small fraction of the incident sunlight is reflected from Itokawa, making it a very faint object when observed in visible light. It is very hard to observe using telescopes of sizes similar to that of AKARI from ground.
Asteroid size is one of the most sought-after pieces of information. For asteroids that are not explored directly, their sizes can be estimated based on various observations from Earth. The temperature of asteroids is determined by the balance between the energy input from incident sunlight, and the output, emitted as infrared radiation.
Existing computer models estimate the temperature distribution in asteroids by considering their shape, rotational motion, and surface conditions.
Observational data in the mid-infrared gives information on the infrared light emitted by the asteroid. Asteroid size can be derived by comparing observational data in the mid-infrared, with that expected from the calculations of the model. The models can further be improved by using the infrared observational data of well-studied asteroids, such as Itokawa.
AKARI has also made observations of possible candidates for future asteroid exploration. It is expected that this detailed information will help greatly further our knowledge of these interesting relics of our Solar System.
Note: This story has been adapted from a news release issued by European Space Agency.

Fausto Intilla

www.oloscience.com

New Information On Geological And Volcanic Activity On The Moon

Source:

http://www.sciencedaily.com/releases/2007/08/070822132131.htm

Science Daily — Owing to SMART-1’s high resolution and favourable illumination conditions during the satellite’s scientific operations, data from Europe’s lunar orbiter is helping put together a story linking geological and volcanic activity on the Moon.

The combination of high-resolution data from SMART-1’s AMIE micro-camera and data from the US Clementine mission is helping scientists determine the tectonics of the Moon’s giant basins and the history of volcanic flooding of mid-sized craters, inside and around the lunar basins.
“Thanks to low-elevation solar illumination on these high-resolution images”, says SMART-1 Project Scientist Bernard Foing, “it is now possible to study fine, small-scale geological features that went undetected earlier.”
The study provides new information on the thermal and tectonic history of the Moon and the processes following the formation of the large basins. There are approximately 50 recognizable lunar basins more than 300 km in diameter. They are believed to be created by the impact of asteroids or comets during the Lunar Late Heavy Bombardment period, 350-750 million years after the formation of the Moon. Some of these basins (mostly on the near side) were then filled in by lava originating from volcanic activity.
Combining information from SMART-1 and Clementine makes it possible to assess the link between fine geological structures, identified for the first time with AMIE’s high resolution, and the chemical composition of the study area.*
The Humorum basin is an ‘ideal’, circular, compact and moderately thick basin that was created by a simple impact event, showing a thin crust and mass concentration within a small area (from Clementine topography and gravity data).*
The Procellarum basin, or Oceanus Procellarum, is a large, extended, complex basin that is moderately thick and shows no mass concentration. It may have been formed by faulting associated with the formation of the adjacent Imbrium crater (3.84 thousand million years ago), rather than by a ‘gargantuan’ impact.*
The Humorum basin shows concentric graben, or elongated, trench-like erosional features around the edge of the basin. These are formed as the crust is deformed due to the presence of a mascon (mass concentration or ‘local overweight’).*
“Lunar crust is like a fragile skin, wrinkled due to local mascons or its thermal history”, says Bernard Foing, “as doctors, we searched for these skin-imprints but some may be masked underneath the last layers of basalt.”
For the first time, strike-slip faults have been observed with SMART-1 in the Humorum basin. These are faults where the rupture is vertical and one side slides past the other. An example is the San Andreas fault along the western United States. However, there is no multi-plate tectonic activity on the Moon.
Procellarum is an extended basin, where the crust is thin enough to allow magma to arise from under the surface, 4 to 2 thousand million years ago. SMART-1 images do not show geological faults, or surfaces where the rock ruptures due to differential movement, in the Procellarum basin.
Procellarum shows wrinkle ridges that are not distributed radially around the basin. Due to their location, they do not seem associated with mascon tectonics, but are mostly results of thermal and mechanical deformation resulting from volcanic activity - basalt extruded by the lava causes compression in the area. The Procellarum basin contains the youngest basalt found on the Moon so far, up to 2 thousand million years old.
Different ‘pulses’ of volcanic activity in lunar history created units of lava on the surface. The flooding of mid-sized craters with lava due to volcanic activity in the region is reflected in the mineralogical map. Differences in the mineralogical composition provide a tool to study the geological history of the region. Flooded as well as unflooded craters are found in the region, reflecting the evolution of volcanic activity with time.
“This analysis shows the potential of the AMIE camera”, says Jean-Luc Josset, Principal Investigator for the AMIE camera, “and we are still analysing other datasets that make use of the varying illumination conditions during the operation of SMART-1 over one and half years”.
The results reflected in the article appear in ‘Coupling between impacts and lunar volcanism for Humorum and Procellarum basins’ by S. Peters, B. Foing, D. Koschny, A. Rossi and the SMART-1 AMIE team, presented at the European Planetary Science Congress on 22 August 2007.
*Images: http://www.esa.int/esaSC/SEMCXRWZK5F_index_0.html
Note: This story has been adapted from a news release issued by European Space Agency.

Fausto Intilla

www.oloscience.com

Astronomers Find Gaping Hole In The Universe

Source:

http://www.sciencedaily.com/releases/2007/08/070823164846.htm

Science Daily — University of Minnesota astronomers have found an enormous hole in the Universe, nearly a billion light-years across, empty of both normal matter such as stars, galaxies and gas, as well as the mysterious, unseen "dark matter." While earlier studies have shown holes, or voids, in the large-scale structure of the Universe, this new discovery dwarfs them all.

"Not only has no one ever found a void this big, but we never even expected to find one this size," said Lawrence Rudnick of the University of Minnesota astronomy professor. Rudnick, along with grad student Shea Brown and associate professor Liliya Williams, also of the University of Minnesota, reported their findings in a paper accepted for publication in the Astrophysical Journal.
Astronomers have known for years that, on large scales, the Universe has voids largely empty of matter. However, most of these voids are much smaller than the one found by Rudnick and his colleagues. In addition, the number of discovered voids decreases as the size increases.
"What we've found is not normal, based on either observational studies or on computer simulations of the large-scale evolution of the Universe," Williams said.
The astronomers drew their conclusion by studying data from the NRAO VLA Sky Survey (NVSS), a project that imaged the entire sky visible to the Very Large Array (VLA) radio telescope, part of the National Science Foundation's National Radio Astronomy Observatory (NRAO). Their study of the NVSS data showed a remarkable drop in the number of galaxies in a region of sky in the constellation Eridanus, southwest of Orion.
"We already knew there was something different about this spot in the sky," Rudnick said. The region had been dubbed the "WMAP Cold Spot," because it stood out in a map of the Cosmic Microwave Background (CMB) radiation made by the Wilkinson Microwave Anisotopy Probe (WMAP) satellite, launched by NASA in 2001. The CMB, faint radio waves that are the remnant radiation from the Big Bang, is the earliest "baby picture" available of the Universe. Irregularities in the CMB show structures that existed only a few hundred thousand years after the Big Bang.
The WMAP satellite measured temperature differences in the CMB that are only millionths of a degree. The cold region in Eridanus was discovered in 2004.
Astronomers wondered if the cold spot was intrinsic to the CMB, and thus indicated some structure in the very early Universe, or whether it could be caused by something more nearby through which the CMB had to pass on its way to Earth. Finding the dearth of galaxies in that region by studying NVSS data resolved that question.
"Although our surprising results need independent confirmation, the slightly lower temperature of the CMB in this region appears to be caused by a huge hole devoid of nearly all matter roughly 6-10 billion light-years from Earth," Rudnick said.
How does a lack of matter cause a lower temperature in the Big Bang's remnant radiation as seen from Earth"
The answer lies in dark energy, which became a dominant force in the Universe very recently, when the Universe was already three-quarters of the size it is today. Dark energy works opposite gravity and is speeding up the expansion of the Universe. Thanks to dark energy, CMB photons that pass through a large void just before arriving at Earth have less energy than those that pass through an area with a normal distribution of matter in the last leg of their journey.
In a simple expansion of the universe, without dark energy, photons approaching a large mass -- such as a supercluster of galaxies -- pick up energy from its gravity. As they pull away, the gravity saps their energy, and they wind up with the same energy as when they started.
But photons passing through matter-rich space when dark energy became dominant don't fall back to their original energy level. Dark energy counteracts the influence of gravity and so the large masses don't sap as much energy from the photons as they pull away. Thus, these photons arrive at Earth with a slightly higher energy, or temperature, than they would in a dark energy-free Universe.
Conversely, photons passing through a large void experience a loss of energy. The acceleration of the Universe's expansion, and thus dark energy, were discovered less than a decade ago. The physical properties of dark energy are unknown, though it is by far the most abundant form of energy in the Universe today. Learning its nature is one of the most fundamental current problems in astrophysics.
This research at the University of Minnesota is supported by individual investigator grants from the NSF and NASA.
Note: This story has been adapted from a news release issued by University of Minnesota.

Fausto Intilla

www.oloscience.com

In Search Of Interstellar Dragon Fire

Source:

http://www.sciencedaily.com/releases/2007/08/070821172205.htm

Science Daily — Ancient explorers set sail expecting to encounter dragons on the world's unknown oceans. NASA's twin Voyager spacecraft are searching for dragons of a different sort as they enter the boundary of our solar system – cosmic "dragons" that breathe a strange fire of high-speed atomic fragments called cosmic rays.

Just as mythical dragons were expected to inhabit stormy seas, these cosmic dragons could be found among turbulent magnetic fields powered by the colliding winds of stars, including our sun. The winds clash at the edge of our solar system, and space physicists wonder if these dragons may be found there, or if they are even more distant in interstellar space.
"Does a great dragon, in the form of a cosmic-ray accelerator, lurk within the turbulent boundary of our solar system to breathe out the fire of cosmic rays, or do these rays arise from even more powerful dragons somewhere in deep space?" asks Dr. John Cooper of NASA's Goddard Space Flight Center in Greenbelt, Md.
Cosmic rays can cause cancer in unprotected astronauts, and a better understanding of where and how cosmic rays are accelerated will improve predictions of how many will be encountered as astronauts set sail on the new ocean of space.
This ocean is not empty. The sun exhales a thin, hot wind of electrically conducting gas, called plasma, into space at many hundreds of miles per second. This solar wind forms a large plasma bubble, called the heliosphere, in space around the Sun. Beyond the orbit of Pluto, the solar wind gradually slows as it interacts with inflowing neutral gases from interstellar space, and then abruptly drops in speed to about 30 miles per second (50 kilometers/second) at a thin, invisible boundary around our solar system called the termination shock.
A simple kitchen experiment illustrates how this shock forms. When water runs at high speed from a kitchen faucet down to the bottom surface of the sink, the water hitting this surface first flows quickly and smoothly away from the impact point, but then runs into a circular boundary with slower, more turbulent flow beyond this boundary.
In the kitchen sink experiment, the circular boundary is the termination shock. The turbulent region beyond the shock boundary corresponds to a layer in the outer heliosphere of turbulent plasma flows and magnetic fields called the heliosheath. The boundary of this turbulent layer with the interstellar plasma environment, not so easily seen in the kitchen sink experiment because of the turbulence, is called the heliopause.
Our solar system is engulfed in a "dragon fire" of cosmic rays with a wide range of energy levels (the faster the cosmic ray, the greater its energy). Some are from known dragons like explosive flares on the sun. Astronomers believe the rays with the highest energy come from the largest dragons in the universe, including exploding stars called supernova, fast-rotating collapsed objects called neutron stars with incredibly strong magnetic fields, the heaviest collapsed stars called black holes that voraciously feed on infalling matter and spit out accelerated particles, and huge magnetic shock structures ejected far into interstellar space from these stellar sources. The energy for cosmic ray acceleration in all these sources comes from twisting, writhing motions of lower-energy charged particles in turbulent magnetic fields.
Nearer our solar system, Cooper is seeking the smaller dragons that breathe out lower energy fire, the so-called "suprathermal" cosmic rays. This suprathermal zone of fire spans a huge range in energy between that of the flowing plasma and the higher-energy cosmic rays. These suprathermal cosmic rays have been measured within the known heliosphere and theoretically modeled by Dr. Len Fisk and his collaborators at the University of Michigan.
Cooper's new idea is that similar energy distributions of such particles may be found in interstellar space. If the Voyager spacecraft eventually cross the heliopause and find this same suprathermal fire in interstellar space, it would mean that the fire breathers live outside the heliosphere.
Most space plasma scientists had expected the termination shock, traversed by Voyager 1 on December 16, 2004, to be the primary energy source for these suprathermal cosmic rays, but nothing was found. "I propose that that the fabled dragon of the termination shock breathes no fire and is a kinder and gentler creature, more like Puff the Magic Dragon," said Cooper. "I believe that the suprathermal cosmic rays we see within our solar system instead arise from even more powerful 'dragons' somewhere in interstellar space."
Cooper suggests that the zone of fire extends higher in energy within interstellar space and that Voyager 1 measurements are gradually revealing this expanded energy range during outward movement through the heliosheath towards the heliopause. He recently presented a paper on his new theory at the 2007 International Cosmic Ray Conference at Merida, Mexico. This conference took place on the Yucatan peninsula where an asteroid impact ended the long earthy reign of real dragons, the dinosaurs, sixty-five million years ago.
Cooper's idea was surprising at first, because the magnetic field carried by the solar wind into the heliosheath was expected to deflect both the incoming interstellar plasma and the suprathermal cosmic rays away from the heliosphere on approach to the heliopause boundary. Current theory is that the suprathermal cosmic rays are found inside the solar system because they sneak across the heliopause into the heliosphere as electrically neutral atoms, which are not deflected by magnetic force. Once inside the solar system, they become electrically charged as the sun's radiation strips electrons off of them. Once charged, they feel magnetic force and are carried out of the solar system by the magnetic field embedded in the solar wind. When they reach the termination shock, they are accelerated by the clashing magnetic fields there and shot back into the solar system, where we detect them as suprathermal cosmic rays.
However, since Voyager 1 has not yet found fully definitive evidence that the termination shock accelerates cosmic rays, Cooper thinks that instead they come from interstellar space. "The magnetic 'shield' formed by the solar wind is probably not smooth. Instead, as the solar wind crashes into the plasma found in interstellar space, it may roll and billow like a cloud, distorting the magnetic field carried with it. I believe interstellar suprathermal cosmic rays can slip between these folds to enter our solar system."
Another possibility is that the dragon lies somewhere between the termination shock and interstellar space, in the vast, teardrop-shaped region around the solar system called the heliosheath. This is where the low-speed solar wind piles up against the interstellar plasma. It forms a teardrop shape as our solar system moves through the galaxy. "However, Voyager 1 has sailed through the heliosheath for two and a half years since crossing the termination shock, and no other local acceleration source has been detected," said Cooper.
Cooper's theory will be tested again soon as the second Voyager spacecraft crosses the termination shock. "If Voyager 2 also finds no evidence of local cosmic ray acceleration as it crosses the termination shock, it will strengthen the case for more remote dragons in interstellar space, perhaps very far beyond in the galaxy, as the source of suprathermal cosmic rays," said Cooper. The first direct traces of these fiercer dragons may be found when the two Voyager spacecraft eventually cross the heliopause into local interstellar space.
Note: This story has been adapted from a news release issued by National Aeronautics And Space Administration.

Fausto Intilla
www.oloscience.com