Posted on by Fraser Cain

Close View of Epimetheus

Cassini view of Saturn’s moon Epimetheus, taken from 74,600 kilometers (46,350 miles) away. Image credit: NASA/JPL/SSI. Click to enlarge.
With this false-color view, Cassini presents the closest look yet at Saturn’s small moon Epimetheus (epp-ee-MEE-thee-uss).

The color of Epimetheus in this view appears to vary in a non-uniform way across the different facets of the moon’s irregular surface. Usually, color differences among planetary terrains identify regional variations in the chemical composition of surface materials. However, surface color variations can also be caused by wavelength-dependent differences in the way a particular material reflects light at different lighting angles. The color variation in this false-color view suggests such “photometric effects” because the surface appears to have a more bluish cast in areas where sunlight strikes the surface at greater angles.

This false color view combines images obtained using filters sensitive to ultraviolet, polarized green and infrared light. The images were taken at a Sun-Epimetheus-spacecraft, or phase, angle of 115 degrees, thus part of the moon is in shadow to the right. This view shows an area seen only very obliquely by NASA’s Voyager spacecraft. The scene has been rotated so that north on Epimetheus is up.

The slightly reddish feature in the lower left is a crater named Pollux. The large crater just below center is Hilairea, which has a diameter of about 33 kilometers (21 miles). At 116 kilometers (72 miles) across, Epimetheus is slightly smaller than its companion moon, Janus (181 kilometers, or 113 miles across), which orbits at essentially the same distance from Saturn.

The images for this color composite were obtained with the Cassini spacecraft narrow-angle camera on March 30, 2005, at a distance of approximately 74,600 kilometers (46,350 miles) from Epimetheus. Resolution in the original images was about 450 meters (1,480 feet) per pixel. This view has been magnified by a factor of two to aid visibility.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . For additional images visit the Cassini imaging team homepage http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Posted on by Fraser Cain

Dust Devils Spotted on Mars

NASA’s Mars Exploration Rover Spirit is taking movies of dust devils — whirlwinds carrying dust — scooting across a plain on Mars.

Clips consisting of a few frames of two different dust devils are available online at http://www.nasa.gov/vision/universe/solarsystem/mer_main.html and http://marsrovers.jpl.nasa.gov. These were taken on April 15 and April 18, and capture more movement as seen from the surface than any previous imaging of martian dust devils.

“This is the best look we’ve ever gotten of the wind effects on the martian surface as they are happening,” said Dr. Mark Lemmon, a rover team member and atmospheric scientist at Texas A&M University, College Station.

Spirit, operated from NASA’s Jet Propulsion Laboratory in Pasadena, Calif., has been using its navigation camera to routinely check for dust devils. It began seeing dust devils last month in individual frames from the camera. Lemmon said, “We’re hoping to learn about how dust is kicked up into the atmosphere and how the wind is interacting with the surface. It’s exciting that we now have a systematic way of capturing dust devils in movies rather than isolated still images.”

Spirit and its twin, Opportunity, successfully completed three-month primary missions in April, 2004, and have been exploring at increasing distances from their landing sites since then.

JPL, a division of the California Institute of Technology in Pasadena, manages NASA’s Mars Exploration Rover project for NASA’s Science Mission Directorate, Washington.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Space Elevator Group to Manufacture Nanotubes

LiftPort Group, the space elevator companies, today announced plans for a carbon nanotube manufacturing plant, the company’s first formal facility for production of the material on a commercial scale. Called LiftPort Nanotech, the new facility will also serve as the regional headquarters for the company, and represents the fruition of the company’s three years of research and development efforts into carbon nanotubes, including partnering work with a variety of leading research institutions in the business and academic communities.

Set to open in June of this year, LiftPort Nanotech will be located in Millville, New Jersey, a community with a history in glass and plastics production. Both the City of Millville and the Cumberland County Empowerment Zone are partnering to provide $100,000 in initial seed money for the new facility.

LiftPort Nanotech will make and sell carbon nanotubes to glass, plastic and metal companies, which will in turn synthesize them into other stronger, lighter materials (also known as composites) for use in their applications. Already being used by industries such as automotive and aerospace manufacturing, carbon nanotube composites are lighter than fiberglass and have the potential to be up to 100 times stronger than steel.

“We are pleased that LiftPort has selected Millville as the location for its new manufacturing facility and regional headquarters,” said Sandra Forosisky, Executive Director of the Cumberland Empowerment Zone. “Millville has a strong history in manufacturing, and we believe it is ideally suited for the emerging carbon nanotube industry.” Mayor James Quinn from the City of Millville added, “LiftPort’s presence will give Millville a competitive advantage in the emerging use of nanotube composites within our existing manufacturing base and its ability to attract additional manufacturing companies resulting in the creation of many new well paying jobs for our community.”

“We selected Millville due both to its central location to key business centers on the East Coast, as well as its experienced workforce,” said Michael Laine, president of LiftPort Group. “In addition, we selected the area because of its growing reputation for supporting the development of cutting edge technologies in a variety of arenas, such as low-cost, green energy.”

Today’s announcement represents the second major facility and first East Coast presence to be established by LiftPort Group, the Seattle-based company dedicated to the development of the first commercial elevator to space. The company was founded by Laine, one of the pioneers of the modern Space Elevator concept and the creator of the modern business model for building a commercial space elevator.

“We see the development of carbon nanotubes as critical to the building of the space elevator,” said Laine. “Opening a commercial production facility enables us to generate revenues in the shorter term by meeting the growing market need for this material. At the same time, it enables us to conduct research and development in this arena for our longer term goal of a commercial space elevator.”

A revolutionary way to send cargo into space, the space elevator (as proposed by LiftPort) will consist of a carbon nanotube composite ribbon stretching some 62,000 miles from earth to space. The elevator will be anchored to an offshore sea platform near the equator in the Pacific Ocean, and to a small counterweight in space. Mechanical lifters will move up and down the ribbon, carrying such items as satellites and solar power systems into space. More information can be obtained at the company’s web site at www.liftport.com.

Original Source: Liftport News Release

Posted on by Fraser Cain

Strange Dust Cloud Found Around Enceladus

The Cassini spacecraft has discovered intriguing dust particles around Saturn’s moon Enceladus. The particles might indicate the existence of a dust cloud around Enceladus, or they may have originated from Saturn’s outermost ring, the E-ring.

“We are making measurements in the plane of the E-ring,? said Dr. Thanasis Economou, a senior scientist at the University of Chicago’s Enrico Fermi Institute. Economou is the lead researcher on the high rate detector, part of a larger instrument on Cassini called the cosmic dust analyzer. “It will take a few more flybys to distinguish if the dust flux is originating from the E-ring as opposed to a source at Enceladus.”

Enceladus is rapidly becoming a very interesting target for Cassini. So much so that scientists and engineers are planning to revise the altitude of the next flyby to get a closer look. Additional Cassini encounters with Enceladus are scheduled for July 14, 2005, and March 12, 2008. The July 14 flyby was to be at an altitude of 1,000 kilometers (620 miles), but the mission team now plans to lower that altitude to about 175 kilometers (109 miles). This will be Cassini’s lowest-altitude flyby of any object during its nominal four-year tour.

Earlier this year Cassini completed two flybys of Enceladus. On February 17, Cassini encountered Enceladus at an altitude of 1,167 kilometers (725 miles). On that date, the cosmic dust analyzer with its high rate detector recorded thousands of particle hits during a period of 38 minutes. Cassini executed another flyby of Enceladus on March 9 at an altitude of 500 kilometers (310 miles). “Again we observed a stream of dust particles,” said Economou. The largest particles detected measure no more than the diameter of a human hair — too small to pose any danger to Cassini.

Scientists have speculated that Enceladus is the source of Saturn’s E ring, the planet’s widest, stretching 302,557 kilometers (188,000 miles). It’s possible, the scientists say, that tidal interactions between Enceladus and Mimas, two other moons of Saturn, have heated Enceladus’ interior causing water volcanism.

“These measurements are extremely important in order to understand the role of Enceladus as the source of the water ice particles in the E ring,” said Dr. Ralf Srama, of the Max Planck Institute for Nuclear Physics, Heidelberg, Germany. Srama is principal investigator of the cosmic dust analyzer science team. This study requires precise measurements of dust densities near the Enceladus region, “but without the high rate detector this would not be possible,” said Srama.

Another of Cassini’s instruments, the magnetometer, recently discovered water ions which could be part of a very thin atmosphere around Enceladus. Enceladus is a relatively small moon. The amount of gravity it exerts is not enough to hold an atmosphere very long. Therefore a strong, continuous source is required to maintain the atmosphere.

Enceladus measures 500 kilometers (310 miles) in diameter and reflects nearly 100 percent of the light that hits its ice- covered surface. It orbits Saturn at a distance of approximately 237,378 kilometers (147,500 miles), about two-thirds the distance from Earth to the Moon.

The cosmic dust analyzer provides direct observations of small ice or dust particles in the Saturn system in order to investigate their physical, chemical and dynamical properties. It is made up of two detectors. The University of Chicago built the high rate detector, which made these observations. With further analysis, the cosmic dust analyzer might be able to determine whether the particles are made of ice or dust.

For images and information on the Cassini mission visit http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL.

Original Source: NASA/JPL News Release

Posted on by Nancy Atkinson

Has Spirit Found Bedrock in Columbia Hills?

In December of 2004, the mission scientists for the Mars Exploration Rover Spirit spied a ridge near the top of Husband Hill, one of the seven Columbia Hills located near the middle of Mars? Gusev Crater. Steve Squyres, Principal Scientific Investigator for the MER Mission, started calling the ridge ?Larry?s Lookout? and the mission team decided to send Spirit to that ridge to determine what it was and use it as a ?perch? to take a panorama of the valley that it overlooked. They knew it would be a challenge given the sand, steep slope, and rocks in the area, but the scientists are now discovering that the arduous climb was well worth it. According to one geologist, what Spirit is finding at Larry?s Lookout could turn out to be one of the highlights of the MER mission.

The ?Larry? of Larry?s Lookout is Dr. Larry Crumpler; field geologist, volcanologist, and Research Curator at the New Mexico Museum of Natural History and Science in Albuquerque, New Mexico. He is also a mission scientist for MER.

Spirit had originally approached and climbed Larry?s Lookout from the rear, and from that perspective the Lookout appeared to be just a knob on the hill.

But then the rover moved around to the side of Larry?s Lookout, and took a picture that caught the immediate attention of Squyres and other mission scientists. The image looks north along the ridge of the Columbia Hills with Spirit sitting on Husband Hill, and the camera pointed at Clark Hill. The hills are strewn with rocks, and in the foreground are two tilting rocks. The big outcrop just behind the rocks is Larry?s Lookout.

Dr. Crumpler explained the image and the questions it provoked: ?From this perspective, we can see that the outcrop has a tilted look. The two boulders in front of the outcrop appear to be orientated in the same direction. And in the hill in the distance to the right you can see layers that appear to be oriented at the same angles. And to the left, there are outcrops that are oriented at exactly the same angle. The overall impression is that there is some sort of organized layering or structure to the hills. Our big question is, is it just something draped over top of the hills, like ash fall draped over it like snow, or is it an indication of the internal arrangement of the bedding planes in the hills? Did the hills originally form by bulging up, and were the beds originally horizontal? Or did some sort of weathering occur? Any of those interpretations are interesting because it says something has happened subsequent to the original formation of the rocks and hills themselves.?

Crumpler said that this is one of the most interesting areas that Spirit has yet encountered, and the first indication of extensive bedrock. ?For the first time we have started to feel hopeful that we can make sense of the Columbia Hills,? he said. ?I think it is going to be a highlight of the mission.?

Crumpler says they are seeing evidence of finely bedded materials in the rocks, with very fine laminations that signify bedded, sediment-like materials. ?This all indicates that we?re not just looking at volcanic rocks or old broken up rocks, but there is some sort of organized layering,? he said. ?We?re going to do a full scale campaign to try to understand all of these things.? Although the MER science team still has a plethora of unanswered questions about this area of the Columbia Hills, from the evidence so far, water is likely to be at least part of the final equation.

Spirit is just about to begin studying the rock outcrop informally dubbed ?Methuselah,? just to the left of the rover tracks in the image. ?Spirit is looking at this outcrop that is dipping to the northwest and looks like it is laminated with bedding planes,? said Crumpler. ?It is a foot-high outcrop with an odd angle that indicates structure or a deposition that took place on a slope.?

Over the weekend of April 23-24, Spirit was ordered to take a panoramic image of the outcrop in order to give the scientists an overview of the overall pattern and layout of the area.

Crumpler noted that there is a considerable age difference between the Columbia Hills and the lava plain that Spirit crossed to reach the Hills. He likened the Hills to a sandstone butte surrounded by fresh, young lava flows, similar to the landscape that is found in the United States? Southwest. ?The Hills are much, much older,? Crumpler said. ?You can actually see the contact between the two where the lava flows sort of lapped up on the edges of the Hills. When you cross that boundary you go from the basalts which show only small amounts of weathering and alteration to the rocks on the Columbia Hills that are totally ?grunged-up? and altered, and basically water-soaked at some time in their history.?

?We?re still trying to figure out what?s going on here,? Crumpler added, ?but the outcrop we are looking at is giving us some good clues.?

Crumpler has had extensive experience in field geology, and said he has spent a lot of his time walking across New Mexico?s lava flows, just as Spirit trekked across the lava flow in Gusev Crater. He?s always had an intense interest in the geologic exploration of other planets and has been involved in some of the mapping programs of Mars, Venus and Io. But he says the MER program is the most exciting mission of which he?s been a part.

?Everyday there has been something different that we hadn?t seen the day before, or some new perspective of the terrain, so I always say that ?today? is the most exciting part of the mission.?

?When you?re in the field,? he continued, ?you keep moving because you?re always curious about what you?re going to find at the next outcrop that will tell you more about what you are trying to figure out. But we are very likely to be here (at Larry?s Lookout) for a long time giving this outcrop our full attention.?

So, it appears Larry?s Lookout will be keeping Spirit and the MER scientists busy for awhile, as they try to unravel the mysteries of the Columbia Hills.

Written by Nancy Atkinson

Posted on by Fraser Cain

200,000 Quasars Confirm Einstein’s Prediction

Applying cutting edge computer science to a wealth of new astronomical data, researchers from the Sloan Digital Sky Survey (SDSS) reported today the first robust detection of cosmic magnification on large scales, a prediction of Einstein’s General Theory of Relativity applied to the distribution of galaxies, dark matter, and distant quasars.

These findings, accepted for publication in The Astrophysical Journal, detail the subtle distortions that light undergoes as it travels from distant quasars through the web of dark matter and galaxies before reaching observers here on Earth.

The SDSS discovery ends a two decade-old disagreement between earlier magnification measurements and other cosmological tests of the relationship between galaxies, dark matter and the overall geometry of the universe.

“The distortion of the shapes of background galaxies due to gravitational lensing was first observed over a decade ago, but no one had been able to reliably detect the magnification part of the lensing signal”, explained lead researcher Ryan Scranton of the University of Pittsburgh.

As light makes its 10 billion year journey from a distant quasar, it is deflected and focused by the gravitational pull of dark matter and galaxies, an effect known as gravitational lensing. The SDSS researchers definitively measured the slight brightening, or “magnification” of quasars and connect the effect to the density of galaxies and dark matter along the path of the quasar light. The SDSS team has detected this magnification in the brightness of 200,000 quasars.

While gravitational lensing is a fundamental prediction of Einstein’s General Relativity, the SDSS collaboration’s discovery adds a new dimension.

“Observing the magnification effect is an important confirmation of a basic prediction of Einstein’s theory,” explained SDSS collaborator Bob Nichol at the University of Portsmouth (UK). “It also gives us a crucial consistency check on the standard model developed to explain the interplay of galaxies, galaxy clusters and dark matter.”

Astronomers have been trying to measure this aspect of gravitational lensing for two decades. However, the magnification signal is a very small effect — as small as a few percent increases in the light coming from each quasar. Detecting such a small change required a very large sample of quasars with precise measurements of their brightness.

“While many groups have reported detections of cosmic magnification in the past, their data sets were not large enough or precise enough to allow a definitive measurement, and the results were difficult to reconcile with standard cosmology,” added Brice Menard, a researcher at the Institute for Advanced Study in Princeton, NJ.

The breakthrough came earlier this year using a precisely calibrated sample of 13 million galaxies and 200,000 quasars from the SDSS catalog. The fully digital data available from the SDSS solved many of the technical problems that plagued earlier attempts to measure the magnification. However, the key to the new measurement was the development of a new way to find quasars in the SDSS data.

“We took cutting edge ideas from the world of computer science and statistics and applied them to our data,” explained Gordon Richards of Princeton University.

Richards explained that by using new statistical techniques, SDSS scientists were able to extract a sample of quasars 10 times larger than conventional methods, allowing for the extraordinary precision required to find the magnification signal. “Our clear detection of the lensing signal couldn’t have been done without these techniques,” Richards concluded.

Recent observations of the large-scale distribution of galaxies, the Cosmic Microwave Background and distant supernovae have led astronomers to develop a ‘standard model’ of cosmology. In this model, visible galaxies represent only a small fraction of all the mass of the universe, the remainder being made of dark matter.

But to reconcile previous measurements of the cosmic magnification signal with this model required making implausible assumptions about how galaxies are distributed relative to the dominant dark matter. This led some to conclude that the basic cosmological picture was incorrect or at least inconsistent. However, the more precise SDSS results indicate that previous data sets were likely not up to the challenge of the measurement.

“With the quality data from the SDSS and our much better method of selecting quasars, we have put this problem to rest,” Scranton said. “Our measurement is in agreement with the rest of what the universe is telling us and the nagging disagreement is resolved.”

“Now that we’ve demonstrated that we can make a reliable measurement of cosmic magnification, the next step will be to use it as a tool to study the interaction between galaxies, dark matter, and light in much greater detail,” said Andrew Connolly of the University of Pittsburgh.

Original Source: SDSS News Release

Posted on by Fraser Cain

Hydrocarbons High in Titan’s Atmosphere

Image credit: NASA/JPL/SSI
During its closest flyby of Saturn’s moon Titan on April 16, the Cassini spacecraft came within 1,027 kilometers (638 miles) of the moon’s surface and found that the outer layer of the thick, hazy atmosphere is brimming with complex hydrocarbons.

Scientists believe that Titan’s atmosphere may be a laboratory for studying the organic chemistry that preceded life and provided the building blocks for life on Earth. The role of the upper atmosphere in this organic “factory” of hydrocarbons is very intriguing to scientists, especially given the large number of different hydrocarbons detected by Cassini during the flyby.

Cassini’s ion and neutral mass spectrometer detects charged and neutral particles in the atmosphere. It provides scientists with valuable information from which to infer the structure, dynamics and history of Titan’s atmosphere. Complex mixtures of hydrocarbons and carbon- nitrogen compounds were seen throughout the range of masses measured by the Cassini ion and neutral mass spectrometer instrument. “We are beginning to appreciate the role of the upper atmosphere in the complex carbon cycle that occurs on Titan,” said Dr. Hunter Waite, principal investigator of the Cassini ion and neutral mass spectrometer and professor at the University of Michigan, Ann Arbor. “Ultimately, this information from the Saturn system will help us determine the origins of organic matter within the entire solar system.”

Hydrocarbons containing as many as seven carbon atoms were observed, as well as nitrogen- containing hydrocarbons (nitriles). Titan’s atmosphere is composed primarily of nitrogen, followed by methane, the simplest hydrocarbon. The nitrogen and methane are expected to form complex hydrocarbons in a process induced by sunlight or energetic particles from Saturn’s magnetosphere. However, it is surprising to find the plethora of complex hydrocarbon molecules in the upper reaches of the atmosphere. Titan is very cold, and complex hydrocarbons would be expected to condense and rain down to the surface.

“Biology on Earth is the primary source of organic production we are familiar with, but the key question is: what is the ultimate source of the organics in the solar system?” added Waite.

Interstellar clouds produce abundant quantities of organics, which are best viewed as the dust and grains incorporated in comets. This material may have been the source of early organic compounds on Earth from which life formed. Atmospheres of planets and their satellites in the outer solar system, while containing methane and molecular nitrogen, are largely devoid of oxygen. In this non-oxidizing environment under the action of ultraviolet light from the Sun or energetic particle radiation (from Saturn’s magnetosphere in this case), these atmospheres can also produce large quantities of organics, and Titan is the prime example in our solar system. This same process is a possible pathway for formation of complex hydrocarbons on early Earth.

This was Cassini’s sixth flyby of Titan, but its exploration has just begun. Thirty-nine more flybys of this strange, remote world are planned during Cassini’s nominal mission. The next Titan flyby is August 22.

The latest images from the Titan flyby are available at: http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini . The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA’s Science Mission Directorate, Washington, D.C.

Original Source: NASA/JPL/SSI News Release

Posted on by Fraser Cain

DIRECTV Satellite Lofted From Sea Launch

Sea Launch Company today successfully delivered DIRECTV?s Spaceway F1 satellite to orbit, completing the launch of the heaviest commercial satellite to date. Early data indicate the spacecraft is in excellent condition.

The Sea Launch Zenit-3SL rocket lifted off at 12:31:30 am PDT (07:31:30 GMT), precisely on schedule, from the Odyssey Launch Platform, positioned at 154 degrees West Longitude. All systems performed nominally throughout the flight. The Block DM-SL upper stage inserted the 6,080 kg (13,376 lb) Spaceway satellite into geosynchronous transfer orbit, on its way to a final orbital position of 102.8 degrees West Longitude. A ground station in South Africa acquired the spacecraft?s first signal less than an hour after liftoff, as planned.

The Boeing 702 model spacecraft, with a design life of 12 years, was manufactured at Boeing?s Satellite Development Center in El Segundo, Calif. It includes a flexible payload with a fully steerable downlink antenna that can be reconfigured on orbit to seamlessly address market conditions.

Following acquisition of the spacecraft?s signal, Jim Maser, president and general manager of Sea Launch, congratulated Boeing and DIRECTV. ?Successfully launching the heaviest commercial satellite to date is a tremendous achievement for everyone involved,? Maser said. It was extremely satisfying for us to provide another great launch for DIRECTV and for Boeing and we look forward to many more in the future. And, once again, our accomplished Sea Launch team has raised the bar ? not only for Sea Launch ? but also for the entire launch industry. We are all especially proud of this latest success. We are the commercial heavy weight champions of the world!?

Sea Launch Company, LLC, headquartered in Long Beach, Calif., and marketed through Boeing Launch Services (www.boeing.com/launch), is the world?s most reliable heavy-lift commercial launch service. This international partnership offers the most direct and cost-effective route to geostationary orbit. With the advantage of a launch site on the Equator, the reliable Zenit-3SL rocket can lift a heavier spacecraft mass or provide longer life on orbit, offering best value plus schedule assurance. For additional information and images of this successfully completed mission, visit the Sea Launch website at: www.sea-launch.com

Original Source: Sea Launch News Release

Posted on by Fraser Cain

Global Warming Could Be Risky for Satellites Too

Image credit: NASA
Climate change is widely attributed to the build-up of greenhouse gases, such as carbon dioxide, in the Earth’s atmosphere. However, scientists from the School of Engineering Sciences at the University of Southampton have shown that the impact of carbon dioxide is being felt in space too.

Dr Hugh Lewis from the School will present a paper to the Fourth European Conference on Space Debris at the European Space Operations Centre (ESOC) in Germany this week indicating that increasing levels of CO2 are causing the amount of space debris orbiting the Earth to increase faster than previously thought.

Whilst CO2 is causing a global rise in temperature at the Earth’s surface, it has the opposite effect in the upper part of the atmosphere known as the thermosphere. Here, in a region of space that contains the International Space Station and many other satellites, the temperature and the atmospheric density are falling rapidly.

Evidence from the Naval Research Laboratory in the USA suggests that the atmospheric density at these heights could be halved in the next 100 years. At first glance, this is good news for satellite operators: it will take longer for their satellites to re-enter the atmosphere. However, the research conducted at the University of Southampton in collaboration with QinetiQ shows that in the later half of this century satellites would be at greater risk from collisions with orbiting debris.

Collisions between objects orbiting the Earth can release as much energy as ten sticks of dynamite because of the enormous speeds involved, around ten kilometres per second. These events can subsequently produce hundreds of thousands of objects larger than 1cm – each one a collision risk to satellites and used rocket stages.

According to the research team’s initial predictions a process known as ‘collision cascading’ – where the number of collisions in orbit increases exponentially – could occur much more quickly in the region of space between 200 km and 2,000 km above the Earth in response to rising CO2 levels. Simulations of a ‘business as usual’ scenario, where satellites are launched and destroyed at the rate they are now, show a 17 per cent increase in the number of collisions and a 30 per cent increase in the number of objects larger than 1cm by the end of the 21st century.

Dr Lewis stresses that steps are already being taken to diminish the threat posed by orbiting debris. The Inter-Agency Space Debris Coordination Committee (IADC), an international governmental forum that coordinates activities related to the issues of debris in space, has produced a set of guidelines that identify mitigation options. Whilst Dr Lewis’ research has implications for these guidelines, he believes that they will remain effective measures: ‘We are only now beginning to understand the impact that polluting the atmosphere is having on space, but our knowledge of the problems posed by space debris is reliable,’ he commented.

The research was undertaken by Dr Lewis, with Dr Graham Swinerd and Charlotte Ellis of the School of Engineering Sciences, and Dr Clare Martin of QinetiQ.

Original Source: University of Southampton News Release

Posted on by Fraser Cain

What’s Up This Week – Apr 25 – May 1, 2005

Image credit: NOAO/AURA/NSF
Monday, April 25 – Today marks the 15th anniversary of the deployment of Hubble Space Telescope. While everyone in the astronomical community is well aware of what this magnificent telescope “sees”, did you know that you can see it with just your eyes? The HST is a satellite that can be tracked and observed. Visit Heaven’s Above and enter your location. This page will provide you with a list of visible passes for your area. Although you can’t see details of the scope itself, it’s great fun to track with binoculars or see the Sun glinting off its surface in a scope.

Before the Moon rises tonight, let’s use our binoculars and telescopes to hunt down one of the best globular clusters for the northern hemisphere – M3. You can locate it easily by identifying last week’s study stars, Cor Caroli and Arcturus. Sweep your binoculars in a line between the two and you will discover this ancient beauty about halfway between the pair just east of Beta Comae. The more aperture you use – the more stars you will resolve.

Discovered by Charles Messier on May 3, 1764, this ball of approximately a half million stars is one of the oldest formations in our galaxy. At around 35-40,000 light years away, this awesome globular cluster spans about 220 light years and is believed to be as much as 10 billion years old. To get a grasp on that concept – our own Sun is less than half that age!

Keep a watch on the skies tonight as the Mu Virginid meteor shower reaches its peak at 7 to 10 per hour. Although the rising Moon will hamper observations, you still might catch one of these medium speed meteors radiating from a point near the constellation of Libra.

Tuesday, April 26 – This morning Mercury will reach its greatest western elongation. Southern hemisphere views are highly favoured for this apparition, and you may spot the swift inner planet just before dawn about a handspan above the east/northeast horizon.

On this date in 1920, the Shapely-Curtis debate raged in Washington on the nature and distance of spiral nebula. Shapely claimed they were part of one huge galaxy to which we all belonged, while Curtis maintained they were distant galaxies of their own. Thirteen years later on the same date, Arno Penzias was born. He went on to become a Nobel Prize winner for his part in the discovery of the cosmic microwave background radiation through a simple horn antenna. His discovery helped further our understanding of cosmology in ways that Shapely and Curtis could have never dreamed.

Before the Moon rises tonight, why not take the telescopic challenge to view one of the largest and finest of face-on spiral galaxies? Located about a fist’s width east of last week’s study – Mizar and Alcor – you will find the large, diffuse M101 to be easily within range of the average mid-sized scope. At magnitude 9, you can spot it in larger binoculars, but will require at least a 10″ scope to detect its knotted arms.

For all of Europe and northeastern Africa, the Moon will occult Antares tonight. Be sure to check IOTA for precise times in your area. On this same universal date, it will also occult bright Sigma Scorpii for those in northwestern Australia.

Wednesday, April 27 – Let’s return to the binoculars and small telescopes tonight to find a fantastic galactic cluster known as the M67. Easily located by either going about a fist’s width south of the M44 or a thumb’s width west of Alpha Cancri – this rich, 2500 light year distant open cluster has a stellar population unlike any other. Located about 1500 light years above the plane of the galaxy, the M67 defies the rules by residing in an area not known for galactic clusters – and double defies them by containing population stars similar to a globular cluster. These stars are an indicator of great age, and the M67 may very well be near 10 million years old. For very small binoculars, this beautiful open cluster will appear almost galaxy-like, while progressively larger instruments will resolve it completely.

Thursday, April 28 – Now is your chance to get a first look at the returning Venus. Immediately after sunset, look for it very low on the west/northwest horizon. Try using binoculars to assist you.

Today was a very busy day in astronomy history. Newton published his Principia in 1686 on April 28. In 1774, Francis Baily was born – who went on to revise star catalogs and explain the phenomenon at the beginning and ending of a total solar eclipse which we know as “Baily’s Beads”. 1900 saw the birth of Jan Hendrick Oort, who quantified the Milky Way’s rotation characteristics and envisioned the vast, spherical area of comets outside our solar system that we call the Oort Cloud. Last, but not least was the birth of Bart Jan Bok in 1906 who studied the structure and dynamics of the Milky Way.

Tonight let’s take a look at a visitor from the Oort Cloud, comet 9P/Temple 1. Located just north of Epsilon Virginis, this 10th magnitude comet could be within range of large binoculars, but I would suggest a telescope since there will be many nearby galaxies that could resemble a cometary signature in such a wide field. Even at the eyepiece, this comet will strongly resemble a faint, face-on spiral – but don’t worry – it’s by far brighter than anything nearby. As 9P/Temple 1 is nearing it’s closest approach to the Earth, this will be an outstanding comet to watch in the weeks ahead. Think “Deep Impact”….

For skywatchers, no equipment is necessary to enjoy the Alpha Bootid meteor shower. Pull up a comfortable seat and face orange Arcturus as it climbs the sky in the east. These slow meteors have a fall rate of 6 to 10 per hour and leave very fine trails, making an evening of quiet contemplation most enjoyable.

Friday, April 29 – The Moon is at perigee, its closest approach to Earth – and as luck would have it, reaches maximum libration at 21:00 UT, tipping the north pole our way. If this doesn’t sound very exciting, think of SMART-1 currently up there looking for eternal sunlight! Although the Moon won’t rise until around local midnight, if you’re up late have a go at extreme northern features like Peary, Byrd, Gioja, Main, Challis and Scoresby.

Saturday, April 30 – Frederich Gauss was born on this day in 1777, Known as the “Prince of Mathematics”, Gauss contributed to the field of astronomy in many ways – from computing asteroid orbits to inventing the helioptrope. Out of Gauss’ many endeavors, he is most recognized for his work in magnetism. We understand the term “gauss” as a magnetic unit – a refrigerator magnet carries about 100 gauss while an average sunspot might go up to a 4000. On the most extreme ends of the magnetic scale, the Earth produces about 0.5 gauss at its poles, while a magnetar can produce as much as 10 to the 15th power in gauss units!

While we cannot directly observe a magnetar, those living in the Southern Hemisphere can view a region of the sky where magnetars are known to exist – the Large Magellanic Cloud. Located in the constellation of Dorado, this unaided eye gem is visible even during full moonlight. Stuffed with wonderful features such as the “Tarantula Nebula” – the largest diffuse nebula known in the Universe – and many star clusters, I urge you to get out your telescopes and binoculars and explore…

For southwestern Europe, the Moon will occult 4.5 magnitude star, 59 Saggitarius, on this universal date. Please check the IOTA webpage for details specific to your area.

Sunday, May 1 – On this day in 1949 Gerard Kuiper discovered Nereid, a satellite of Neptune. If you’re up before dawn, you can easily find Neptune less than 2 degrees northwest of bright Mars. While it can be see in binoculars as a bluish “star”, it takes around a 150mm telescope and some magnification to resolve its disc. Today’s imaging technology can even reveal its moons!

Tonight will mark the peak of the Phi Bootid meteor shower whose radiant is near the constellation of Hercules. While the best time to view a meteor shower is around 2:00 a.m. local time, you will have best success watching for these meteors during the late evening before moonrise. The average fall rate is about 6 per hour.

Keep those scopes warm – dark skies are on their way back again! May all your travels be at Light Speed…. ~Tammy Plotner