Posted on by Fraser Cain

Deep Impact Has Its Target in View

Deep Impact’s first view of Comet Temple 1 from a distance of 64 million kilometers (39.7 million miles). Image credit: NASA/JPL. Click to enlarge.
Sixty-nine days before it gets up-close-and-personal with a comet, NASA’s Deep Impact spacecraft successfully photographed its quarry, comet Tempel 1, from a distance of 64 million kilometers (39.7 million miles).

The image, the first of many comet portraits it will take over the next 10 weeks, will aid Deep Impact’s navigators, engineers and scientists as they plot their final trajectory toward an Independence Day encounter. “It is great to get a first glimpse at the comet from our spacecraft,” said Deep Impact Principal Investigator Dr. Michael A’Hearn of the University of Maryland, College Park, Md. “With daily observations beginning in May, Tempel 1 will become noticeably more impressive as we continue to close the gap between spacecraft and comet. What is now little more than a few pixels across will evolve by July 4 into the best, most detailed images of a comet ever taken.”

The ball of dirty ice and rock was detected on April 25 by Deep Impact’s medium resolution instrument on the very first attempt. While making the detection, the spacecraft’s camera saw stars as dim as 11th visual magnitude, more than 100 times dimmer than a human can see on a clear night.

“This is the first of literally thousands of images we will take of Tempel 1 for both science and navigational purposes,” said Deputy Program Manager Keyur Patel at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “Our goal is to impact a one-meter long (39-inch) spacecraft into about a 6.5-kilometer wide (4-mile) comet that is bearing down on it at 10.2 kilometers per second (6.3 miles per second), while both are 133.6 million kilometers (83 million miles) away from Earth. By finding the comet as early and as far away as we did is a definite aid to our navigation.”

To view the comet image on the Internet, visit http://www.nasa.gov/deepimpact or http://deepimpact.jpl.nasa.gov/.

Deep Impact is comprised of two parts, a “flyby” spacecraft and a smaller “impactor.” The impactor will be released into the comet’s path for a planned high-speed collision on July 4. The crater produced by the impact could range in size from the width of a large house up to the size of a football stadium and from 2 to 14 stories deep. Ice and dust debris will be ejected from the crater, revealing the material beneath.

The Deep Impact spacecraft has four data collectors to observe the effects of the collision – a camera and infrared spectrometer comprise the high resolution instrument, a medium resolution instrument, and a duplicate of that camera on the impactor (called the impactor targeting sensor) that will record the vehicle’s final moments before it is run over by comet Tempel 1 at a speed of about 37,000 kilometers per hour (23,000 miles per hour).

The overall Deep Impact mission management for this Discovery class program is conducted by the University of Maryland. Deep Impact project management is handled by the Jet Propulsion Laboratory. The spacecraft was built for NASA by Ball Aerospace & Technologies Corporation, Boulder, Colo.

For more information about Deep Impact on the Internet, visit NASA Deep Impact.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

ESA Astronaut Will Visit Station for Months

ESA astronaut Thomas Reiter from Germany, will be the first to do a long-duration spaceflight. Image credit: ESA. Click to enlarge.
This July, ESA astronaut Thomas Reiter from Germany is about to become the first European to live and work on the International Space Station (ISS) on a long-duration mission.

ESA Director of Human Spaceflight, Microgravity and Exploration, Daniel Sacotte, recently signed an agreement on the mission with the Head of the Russian Federal Space Agency (Roscosmos), Anatoli Perminov. “The agreement covers the ESA astronaut?s flight in a crew position originally planned for a Russian cosmonaut”, explained Sacotte, “and he will perform all the tasks originally allocated to the second Russian cosmonaut on board the ISS and, in addition, an ESA experimental programme.”

The agreement forms part of a set of bilateral understandings between Roscosmos and NASA and between ESA and NASA, enabling the implementation of the mission.

Thomas Reiter, the astronaut assigned to the mission, is a member of the European Astronaut Corps, based at ESA’s European Astronaut Centre (EAC) in Cologne, Germany. L?opold Eyharts, from France, a member of the same Corps, will be the back-up for this mission.

Reiter will reach the ISS on Space Shuttle flight STS-121 currently planned for next July, and return to Earth on flight STS-116 in February.

This will be Reiter’s second long-duration mission on board a space station, following his six-month stay on the Russian Mir, ten years ago, during the ESA Euromir 1995 mission.

“With the maiden flight of the Automated Transfer Vehicle (ATV) and the launch of the European laboratory Columbus, both in 2006, ESA is making important contributions to the ISS and its scientific capabilities and, consequently, we are assuming significant operational responsibilities in this programme. I am confident that this mission will give Europe a lot of operational experience and scientific results which will further prepare us for the exciting and challenging times ahead,” said Thomas Reiter.

“Moreover,” L?opold Eyharts pointed out, “as the back-up astronaut for this mission, I am receiving the same training as Thomas Reiter, which will be an excellent preparation for my tasks as prime astronaut for a future ESA mission to the ISS in connection with Columbus.”

Both astronauts are already in training for the mission in the various ISS training facilities at Houston, Moscow and Cologne, together with their Russian and American astronaut colleagues.

“For the first time, and as a test for later European long-duration missions to the ISS, mission preparation, training, operations and multilateral coordination will be carried out as far as possible through the multilateral decision-making and management structures established for ISS exploitation,” underlined ESA’s Mission Manager Aldo Petrivelli.

“This will be an excellent opportunity for testing coordination and cooperation between ground control and support centres like the Houston and Moscow Mission Control Centres, the Columbus Control Centre in Oberpfaffenhofen, near Munich (*), the European Astronaut Centre in Cologne and the various User Support and Operations Centres throughout Europe that will be involved in the mission. The operational teams from ESA, national space agencies, industry and research institutions in Europe will thus gain very useful operational experience, also for future Columbus system, subsystems and payload operations.”

Original Source: ESA News Release

Posted on by Fraser Cain

Chandra Sees a Bridge Between Stars

Chandra X-Ray view of Mira AB; a red giant star probably orbiting a white dwarf. Image credit: Chandra. Click to enlarge.
For the first time an X-ray image of a pair of interacting stars has been made by NASA’s Chandra X-ray Observatory. The ability to distinguish between the interacting stars – one a highly evolved giant star and the other likely a white dwarf – allowed a team of scientists to observe an X-ray outburst from the giant star and find evidence that a bridge of hot matter is streaming between the two stars.

“Before this observation it was assumed that all the X-rays came from a hot disk surrounding a white dwarf, so the detection of an X-ray outburst from the giant star came as a surprise,” said Margarita Karovska of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and lead author article in the latest Astrophysical Journal Letters describing this work. An ultraviolet image made by the Hubble Space Telescope was a key to identifying the location of the X-ray outburst with the giant star.

X-ray studies of this system, called Mira AB, may also provide better understanding of interactions between other binary systems consisting of a “normal” star and a collapsed star such as a white dwarf, black hole or a neutron star, where the stellar objects and gas flow cannot be distinguished in an image.

The separation of the X-rays from the giant star and the white dwarf was made possible by the superb angular resolution of Chandra, and the relative proximity of the star system at about 420 light years from Earth. The stars in Mira AB are about 6.5 billion miles apart, or almost twice the distance of Pluto from the Sun.

Mira A (Mira) was named “The Wonderful” star in the 17th century because its brightness was observed to wax and wane over a period of about 330 days. Because it is in the advanced, red giant phase of a star’s life, it has swollen to about 600 times that of the Sun and it is pulsating. Mira A is now approaching the stage where its nuclear fuel supply will be exhausted, and it will collapse to become a white dwarf.

The internal turmoil in Mira A could create magnetic disturbances in the upper atmosphere of the star and lead to the observed X-ray outbursts, as well as the rapid loss of material from the star in a blustery, strong, stellar wind. Some of the gas and dust escaping from Mira A is captured by its companion Mira B.

In stark contrast to Mira A, Mira B is thought to be a white dwarf star about the size of the Earth. Some of the material in the wind from Mira A is captured in an accretion disk around Mira B, where collisions between rapidly moving particles produce X-rays.

One of the more intriguing aspects of the observations of Mira AB at both X-ray and ultraviolet wavelengths is the evidence for a faint bridge of material joining the two stars. The existence of a bridge would indicate that, in addition to capturing material from the stellar wind, Mira B is also pulling material directly off Mira A into the accretion disk.

Chandra observed Mira with its Advanced CCD Imaging Spectrometer on December 6, 2003 for about 19 hours. NASA’s Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate, Washington. Northrop Grumman of Redondo Beach, Calif., was the prime development contractor for the observatory. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

Additional information and images are available at:

http://chandra.harvard.edu and http://chandra.nasa.gov

Original Source: Chandra News Release

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