Posted on by Fraser Cain

Closeup Look at Martian Soil

Image credit: NASA/JPL
This magnified look at the martian soil near the Mars Exploration Rover Opportunity’s landing site, Meridiani Planum, shows coarse grains sprinkled over a fine layer of sand. The image was captured by the rover’s microscopic imager on the 10th day, or sol, of its mission and roughly approximates the color a human eye would see. Scientists are intrigued by the perfectly round pebbles, which most likely were formed by one of two geologic processes. The first, accretion, is the same mechanism by which pearls take shape in oysters: concentric layers of material build up around a “seed.” The seed, in this case, may be either waterborne particles or volcanic ash. In the second process, droplets of material are sprayed into the air, by either volcanic eruptions or asteroid impacts. The examined patch of soil is 3 centimeters (1.2 inches) across. The large, circular pebble in the lower left corner is approximately 3 millimeters (.12 inches) across, or about the size of a sunflower seed. This color composite was obtained by merging images acquired with the orange-tinted dust cover in both its open and closed positions. The blue tint at the lower right corner is a tag used by scientists to indicate that the dust cover is closed.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Clouds of Hydrogen Swarm Around Andromeda

Image credit: NRAO
A team of astronomers using the National Science Foundation’s Robert C. Byrd Green Bank Telescope (GBT) has made the first conclusive detection of what appear to be the leftover building blocks of galaxy formation — neutral hydrogen clouds — swarming around the Andromeda Galaxy, located in the Andromeda constellation, the nearest large spiral galaxy to the Milky Way.

This discovery may help scientists understand the structure and evolution of the Milky Way and all spiral galaxies. It also may help explain why certain young stars in mature galaxies are surprisingly bereft of the heavy elements that their contemporaries contain.

“Giant galaxies, like Andromeda and our own Milky Way, are thought to form through repeated mergers with smaller galaxies and through the accretion of vast numbers of even lower mass ‘clouds’ — dark objects that lack stars and even are too small to call galaxies,” said David A. Thilker of the Johns Hopkins University in Baltimore, Maryland. “Theoretical studies predict that this process of galactic growth continues today, but astronomers have been unable to detect the expected low mass ‘building blocks’ falling into nearby galaxies, until now.”

Thilker’s research is published in the Astrophysical Journal Letters. Other contributors include: Robert Braun of the Netherlands Foundation for Research in Astronomy; Rene A.M. Walterbos of New Mexico State University; Edvige Corbelli of the Osservatorio Astrofisico di Arcetri in Italy; Felix J. Lockman and Ronald Maddalena of the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia; and Edward Murphy of the University of Virginia.

The Milky Way and Andromeda were formed many billions of years ago in a cosmic neighborhood brimming with galactic raw materials — among which hydrogen, helium, and cold dark matter were primary constituents. By now, most of this raw material has probably been gobbled up by the two galaxies, but astronomers suspect that some primitive clouds are still floating free.

Previous studies have revealed a number of clouds of neutral atomic hydrogen that are near the Milky Way but not part of its disk. These were initially referred to as high-velocity clouds (HVCs) when they were first discovered because they appeared to move at velocities difficult to reconcile with Galactic rotation.

Scientists were uncertain if HVCs comprised building blocks of the Milky Way that had so far escaped capture, or if they traced gas accelerated to unexpected velocities by energetic processes (multiple supernovae) within the Milky Way. The discovery of similar clouds bound to the Andromeda Galaxy strengthens the case that at least some of these HVCs are indeed galactic building blocks.

Astronomers are able to use radio telescopes to detect the characteristic 21-centimeter radiation emitted naturally by neutral atomic hydrogen. The great difficulty in analyzing these low-mass galactic building blocks has been that their natural radio emission is extremely faint. Even those nearest to us, clouds orbiting our Galaxy, are hard to study because of serious distance uncertainties. “We know the Milky Way HVCs are relatively nearby, but precisely how close is maddeningly tough to determine,” said Thilker.

Past attempts to find missing satellites around external galaxies at well-known distances have been unsuccessful because of the need for a very sensitive instrument capable of producing high-fidelity images, even in the vicinity of a bright source such as the Andromeda Galaxy.

One might consider this task similar to visually distinguishing a candle placed adjacent to a spotlight. The novel design of the recently commissioned GBT met these challenges brilliantly, and gave astronomers their first look at the cluttered neighborhood around Andromeda.

The Andromeda Galaxy was targeted because it is the nearest massive spiral galaxy. “In some sense, the rich get richer, even in space,” said Thilker. “All else being equal, one would expect to find more primordial clouds in the vicinity of a large spiral galaxy than near a small dwarf galaxy, for instance. This makes Andromeda a good place to look, especially considering its relative proximity — a mere 2.5 million light-years from Earth.”

What the GBT was able to pin down was a population of 20 discrete neutral hydrogen clouds, together with an extended filamentary component, which, the astronomers believe, are both associated with Andromeda. These objects, seemingly under the gravitational influence of Andromeda’s halo, are thought to be the gaseous clouds of the “missing” (perhaps dark-matter dominated) satellites and their merger remnants. They were found within 163,000 light-years of Andromeda.

Favored cosmological models have predicted the existence of these satellites, and their discovery could account for some of the missing “cold dark matter” in the Universe. Also, confirmation that these low-mass objects are ubiquitous around larger galaxies could help solve the mystery of why certain young stars, known as G-dwarf stars, are chemically similar to ones that evolved billions of years ago.

As galaxies age, they develop greater concentrations of heavy elements formed by the nuclear reactions in the cores of stars and in the cataclysmic explosions of supernovae. These explosions spew heavy elements out into the galaxy, which then become planets and get taken up in the next generation of stars.

Spectral and photometric analysis of young stars in the Milky Way and other galaxies, however, show that there are a certain number of young stars that are surprisingly bereft of heavy elements, making them resemble stars that should have formed in the early stages of galactic evolution.

“One way to account for this strange anomaly is to have a fresh source of raw galactic material from which to form new stars,” said Murphy. “Since high-velocity clouds may be the leftover building blocks of galaxy formation, they contain nearly pristine concentrations of hydrogen, mostly free from the heavy metals that seed older galaxies.” Their merger into large galaxies, therefore, could explain how fresh material is available for the formation of G-dwarf stars.

The Andromeda Galaxy, also known as M31, is one of only a few galaxies that are visible from Earth with the unaided eye, and is seen as a faint smudge in the constellation Andromeda. When viewed through a modest telescope, Andromeda also reveals that it has two prominent satellite dwarf galaxies, known as M32 and M110. These dwarfs, along with the clouds studied by Thilker and collaborators, are doomed to eventually merge with Andromeda. The Milky Way, M33, and the Andromeda Galaxy plus about 40 dwarf companions, comprise what is known as the “Local Group.”

Today, Andromeda is perhaps the most studied galaxy other than the Milky Way. In fact, many of the things we know about the nature of galaxies like the Milky Way were learned by studying Andromeda, since the overall features of our own galaxy are disguised by our internal vantage point. “In this case, Andromeda is a good analogue for the Milky Way,” said Murphy. “It clarifies the picture. Living inside the Milky Way is like trying to determine what your house looks like from the inside, without stepping outdoors. However, if you look at neighbors’ houses, you can get a feeling for what your own home might look like.”

The GBT is the world’s largest fully steerable radio telescope.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Original Source: NRAO News Release

Posted on by Fraser Cain

Satellites Could Help Predict Landslides

Image credit: ESA
As winter rains come, thousands of square kilometres of territory across Europe’s heart face a looming threat: steep slopes and waterlogged soils combine to trigger landslides.

A build-up of groundwater within a slope increases its weight and decreases its cohesiveness, weakening the slope’s ability to resist the remorseless pull of gravity. The heavy earth flows downward. For all in the path of a landslide the results are devastating, and frequently lethal.

“In Italy, landslides have claimed an average of 54 victims per year during the last half century,” says Nicola Casagli of Italy’s National Group for Hydro-geological Disaster Prevention (GNDCI),a research network working with Italy’s Civil Protection Department.

“The extreme rainfall of our climate, our mountainous geography and recent uncontrolled urbanisation of unstable land makes us one of the countries most affected by landslide hazards. The total cost of direct damage done by Italian landslides is estimated at between one and two thousand million Euro per year.”

Very gradual ground shifts are known to precede more major landslides. Often these are on a scale of millimetres ? too slight to even be noticed by local observers, but enough to be detected via satellite using a powerful technique called radar interferometry.

It involves mathematically combining multiple radar images of the same site – acquired using instruments such as the Synthetic Aperture Radar (SAR) aboard ESA’s ERS spacecraft – in such a way that tiny changes in the landscape occurring between images are highlighted.

This technique is the basis of a new project called Service for Landslide Monitoring (SLAM), enabling landslide susceptibility mapping across parts of Italy and Switzerland, two of the European countries most under threat. GNDCI is one of three national-level users working with SLAM, along with Italy’s Ministry of the Environment and Switzerland’s Federal Office for Water and Geology (FOWG).

“Surface movements assessed over wide areas are one of the best indicators of landslide activity, and can be employed for risk forecasting,” added Casagli. “Extremely slow movements usually occur for several weeks or months before a sudden collapse.”

Trial services are being provided across Italy’s Arno river basin as well as a section of the Campania region. In Switzerland the service covers the eastern Valais and Berne cantons.

“Our interest is to have a tool evaluate landslides and mass displacements all across the Swiss Alps,” explains Hugo Raetzo of FOWG. “About 8% of Swiss territory is vulnerable to landslides, making up thousands of square kilometres. The annual landslide frequency varies with the weather ? heavy rainfall can potentially re-accelerate existing landslides.”

Three different service products are available: a large-scale Landslide Motion Survey identifying areas affected by landslides across an entire river basin, a reduced-scale Landslide Displacement Monitoring measuring ground deformation over particular sites of interest, and Landslide Susceptibility Mapping which merges the previous data products with thematic maps of land use, slope, geomorphology and other relevant parameters to provide geological hazard maps.

More than a decade’s worth of ERS data archives are being exploited to derive SLAM products. These products disclose new and essential information to the institutions charged with landslide risk and hazard management. Benefits from the service include the identification and characterisation of displacements both known and previously unknown and the verification of remedial interventions performed in the past to stabilise particular landslides.

The SLAM service is being formally implemented in February and will run until the end of this year. It is entirely funded as part of ESA’s Data User Programme and is carried out by an international consortium led by Planetek Italia with five other partners: Tele-Rilevamento Europa, Gamma Remote Sensing, Spacebel, Geotest and Florence University.

Original Source: ESA News Release

Posted on by Fraser Cain

Columbia Astronauts Get Mountains on Mars

Image credit: NASA
NASA Administrator Sean O’Keefe today announced the martian hills, located east of the Spirit Mars Exploration Rover’s landing site, would be dedicated to the Space Shuttle Columbia STS-107 crew.

“These seven hills on Mars are named for those seven brave souls, the final crew of the Space Shuttle Columbia. The Columbia crew faced the challenge of space and made the supreme sacrifice in the name of exploration,” Administrator O’Keefe said.

The Shuttle Columbia was commanded by Rick Husband and piloted by William McCool. The mission specialists were Michael Anderson, Kalpana Chawla, David Brown, Laurel Clark; and the payload specialist was Israeli astronaut Ilan Ramon. On February 1, 2003, the Columbia and its crew were lost over the western United States during re-entry into Earth’s atmosphere.

The 28th and final flight of Columbia was a 16-day mission dedicated to research in physical, life and space sciences. The Columbia crew successfully conducted approximately 80 separate experiments during their mission.

NASA will submit the names of the Mars features to the International Astronomical Union for official designation. The organization serves as the internationally recognized authority for assigning designations to celestial bodies and their surface features.

An image taken by the Mars Global Surveyor Mars Orbiter Camera of the Columbia Memorial Station and Columbia Hills is available on the Internet at: http://www.jpl.nasa.gov/mer2004/rover-images/feb-02-2004/captions/image-10.html.

For information about NASA and the Mars mission on the Internet, visit: http://www.nasa.gov.

The Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Exploration Rover project for NASA’s Office of Space Science, Washington, D.C. Additional information about the project is available on the Internet at: http://marsrovers.jpl.nasa.gov.

Posted on by Fraser Cain

Rosetta Launch Date Approaching

Image credit: ESA
The countdown to Rosetta?s rendezvous in space began on 1 March 1997. At the end of February 2004, seven years and not a few headaches later, the European Space Agency (ESA) probe will at last be setting off on its journey to meet 67P/Comet Churyumov-Gerasimenko.

The long-planned get-together will not however take place until the middle of 2014. A few months after arriving at the comet, Rosetta will release a small lander onto its surface. Then, for almost two years it will investigate Churyumov-Gerasimenko from close up.

Dr Gerhard Schwehm, lead scientist for the Rosetta project, explains that, ?With this mission we will be breaking new ground – this will be the first protracted cometary encounter.? The trip to the meeting place in space will certainly be a long one, located as it is some 4.5 astronomical units from the Sun, which translates into something like 675 million kilometres. Rosetta will be on the road for ten years, during which time it will clock up in excess of five billion kilometres.

Launch in February 2004
Rosetta will be waved off on 26 February when it lifts off from the space centre in Kourou, French Guiana, aboard an Ariane 5 launcher. Shortly after the spacecraft?s release, its solar panels will be deployed and turned towards the Sun to build up the necessary power reserves. Its various systems and experiments will be gradually brought into operation and tested. Just three months into the mission the first active phase will be over, followed by final testing of the experiments in October 2004. Rosetta will then spend the following years flying a lonely path to the comet, passing by the Earth, Mars, the Earth and the Earth again.

There is no alternative to this detour, for even Ariane 5, the most powerful launcher on the market today, lacks the power to hurl the probe on a direct route to the comet. To get the required momentum, it will rely on swing-by man?uvres, using the gravitation pull of Mars (in 2007) and the Earth (three times, in 2005, 2007 and 2008) to pick up speed.

Asteroids for company
A change is as good as a rest, and a meeting with at least one asteroid should help break the monotony for Rosetta. The spacecraft will come close to an asteroid at the end of 2008. Asteroids are, it will be remembered, rocky bodies, some as large as mountains, some even larger, that orbit the Sun in much the same way as planets.

?These ?brief encounters? are a scientific opportunity and also a chance to test Rosetta?s instrument payload,? says Gerhard Schwehm. But asteroid exploration also serves an entirely practical purpose: ?The more we find out about them, the better the prospect of being able one day to avert a possible collision.? Following a period of low-activity cruising, the probe?s course will be adjusted one last time in May 2011. From July 2011, a further two-and-a-half years’ radio silence will be observed, and Rosetta, left entirely to its own resources, will fly close to the Jupiter orbit.

Link-up in 2014
Finally, in January 2014, the probe will be reactivated and will, by October 2014, be only a few kilometres distant from Churyumov-Gerasimenko. This is where the dream of so many scientists becomes reality. Having deposited its precious lander cargo on the comet?s surface, Rosetta will continue to orbit Churyumov-Gerasimenko and together they will spend the next seventeen months flying towards the Sun.

Rosetta was built by an international consortium led by Astrium. The lander probe was developed in Cologne under the aegis of the DLR, Germany?s space agency, with contributions from ESA and research centres in Austria, Finland, France, Hungary, Ireland, Italy and Great Britain.

The comet explorer carries ten scientific instruments. Their job is to draw out the secrets of the comet?s chemical and physical composition and reveal its magnetic and electrical properties. Using a specially designed camera, the lander will take pictures in the macro and micro ranges and send all the data thus acquired back to Earth, via Rosetta.

?This will be our first ever chance to be there, at first hand, so to speak, as a comet comes to life,? Schwehm goes on to explain. When Churyumov-Gerasimenko gets to within about 500 million kilometres of the Sun, the frozen gases that envelop it will evaporate and a trail of dust will be blown back over hundreds of thousands of kilometres. When illuminated by the Sun, this characteristic comet tail then becomes visible from Earth. In the course of the mission, the processes at work within the cometary nucleus will be studied and measured more precisely than has ever before been possible, for earlier probes simply flew past their targets.

?As we will be accompanying Churyumov-Gerasimenko for two years, until the comet reaches its closest point to the Sun and travels away from it, we can at long last hope to acquire new knowledge about comets. We are confident we will come a step nearer to understanding the origins and formation of our solar system and the emergence of life on Earth.?

More information on the Rosetta launch can be found on: http://www.esa.int/rosetta

More on ESA Science Programme at: http://www.esa.int/science

Original Source: ESA News Release

Posted on by Fraser Cain

Twin Rovers Examining at the Same Time

Image credit: NASA/JPL
Each of NASA’s two Mars Exploration Rovers is using its versatile robotic arm for positioning tools at selected targets on the red planet.

Also, a newly completed 360-degree color panorama from Opportunity shows a trail of bounce marks coming down the inner slope of the small crater where the spacecraft came to rest when it landed on Mars nine days ago.

Opportunity extended its arm early today for the first time since pre-launch testing. “This was a great confirmation for the team,” said Joe Melko of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. Melko is mechanical systems engineer for the arm, which is also called the instrument deployment device.

Mission controllers at JPL are telling Opportunity to use two of the instruments on the arm overnight tonight to examine a patch of soil in front of the rover. A microscope on the arm will reveal structures as thin as a human hair and a Moessbauer Spectrometer will collect information to identify minerals in the soil, according to plans. Tomorrow, the rover will be told to turn the turret at the end of the arm in order to examine the same patch of soil with another instrument, the alpha particle X-ray spectrometer, which reveals the chemical elements in a target.

Spirit is now in good working order after more than a week of computer-memory problems. It is brushing dust off of a rock today with the rock abrasion tool on its robotic arm. After the brushing, Spirit will use the microscope and two spectrometers on the arm to examine the rock.

“We’re moving forward with our science on the rock Adirondack,” said JPL’s Jennifer Trosper, Spirit mission manager. Reformatting of Spirit’s flash memory was postponed from today to tomorrow. The reformatting is a precautionary measure against recurrence of the problem that prevented Spirit from doing much science last week.

Later in the week, Spirit will grind the surface off of a sample area on Adirondack with the rock abrasion tool to inspect the rock’s interior. After observations of Adirondack are completed, the rover will begin rolling again. “We are already strategizing how to drive far and fast,” Trosper said.

Observations by each rover’s panoramic camera help scientists choose where to drive and what to examine with the instruments on each rover’s arm. Dr. Jeff Johnson, a rover science team member from the U.S. Geological Survey’s Astrogeology Team, Flagstaff, Ariz., said that 14 filters available on each rover’s panoramic camera allow the instrument to provide much more information for identifying different types of rocks than can be gleaned from color images such as the new panoramic view.

“By looking at the brightness values in each of these wavelengths, we can start to get an idea of the things we’re interested in, especially to unravel the geological history of these landing sites,” Johnson said.

The main task for both rovers in coming weeks and months is to find clues in rocks and soil about past environmental conditions, particularly about whether the landing areas were ever watery and possibly suitable for sustaining life.

Each martian day, or “sol” lasts about 40 minutes longer than an Earth day. Spirit begins its 31st sol on Mars at 1:23 a.m. Tuesday, Pacific Standard Time. Opportunity begins its 11th sol on Mars at 1:44 p.m. Tuesday, PST. The two rovers are halfway around Mars from each other.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA’s Office of Space Science, Washington, D.C. Images and additional information about the project are available from JPL at http://marsrovers.jpl.nasa.gov and from Cornell University, Ithaca, N.Y., at http://athena.cornell.edu.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Spirit is Fully Recovered

Image credit: NASA/JPL
NASA’s Mars Exploration Rover Spirit is healthy again, the result of recovery work by mission engineers since the robot developed computer-memory and communications problems 10 days ago.

“We have confirmed that Spirit is booting up normally. Tomorrow we’ll be doing some preventive maintenance,” Dr. Mark Adler, mission manager at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., said Sunday morning.

Spirit’s twin, Opportunity, which drove off its lander platform early Saturday, will be commanded tonight to reach out with its robot arm early Monday, said JPL’s Matt Wallace, mission manager. Opportunity will examine the soil in front of it over the next few days with a microscope and with a pair of spectrometer instruments for determining what elements and minerals are present.

For Spirit, part of the cure has been deleting thousands of files from the rover’s flash memory — a type of rewritable electronic memory that retains information even when power is off. Many of the deleted files were left over from the seven- month flight from Florida to Mars. Onboard software was having difficulty managing the flash memory, triggering Spirit’s computer to reset itself about once an hour.

Two days after the problem arose, engineers began using a temporary workaround of sending commands every day to put Spirit into an operations mode that avoided use of flash memory. Now, however, the computer is stable even when operating in the normal mode, which uses the flash memory.

“To be safe, we want to reformat the flash and start again with a clean slate,” Adler said. That reformatting is planned for Monday. It will erase everything stored in the flash file system and install a clean version of the flight software.

Today, Spirit is being told to transmit priority data remaining in the flash memory. The information includes data from atmospheric observations made Jan. 16 in coordination with downward-looking observations by the European Space Agency’s Mars Express orbiter. Also today, Spirit will make new observations coordinated with another Mars Express overflight and will run a check of the rover’s miniature thermal emission spectrometer.

Spirit will resume examination of a rock nicknamed Adirondack later this week and possibly move on to a lighter-colored rock by week’s end.

Each martian day, or “sol” lasts about 40 minutes longer than an Earth day. Spirit begins its 30th sol on Mars at 12:44 a.m. Monday, Pacific Standard Time. Opportunity begins its 10th sol on Mars at 1:05 p.m. Monday, PST. The two rovers are halfway around Mars from each other.

The main task for both Spirit and Opportunity in coming weeks and months is to find geological clues about past environmental conditions at their landing sites, particularly about whether the areas were ever watery and possibly suitable for sustaining life.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA’s Office of Space Science, Washington, D.C. Images and additional information about the project are available from JPL at http://marsrovers.jpl.nasa.gov and from Cornell University, Ithaca, N.Y., at http://athena.cornell.edu.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Progress Docks with Station

Image credit: NASA
An unmanned Russian resupply ship smoothly linked up to the International Space Station this morning, delivering 2-1/2 tons of food, fuel, spare parts and supplies to the two residents on board.

With Expedition 8 Commander and NASA Science Officer Mike Foale and Flight Engineer Alexander Kaleri looking on, the ISS Progress 13 docked to the aft port of the Zvezda Service Module at 7:13 a.m. CST (1313 GMT) as the two craft flew 230 statute miles above Central Asia.

Foale and Kaleri were in Zvezda, prepared to take over manual control of the operation if it had been necessary, but the Progress craft automatically docked to the module through pre-programmed computer command with no problem.

The Progress was the first ship to arrive at the ISS since Foale and Kaleri were launched more than 100 days ago. They are well past the midway mark of a planned 6-? month mission on the complex. The next ship to reach the Station will be the Soyuz TMA-4 capsule in April, carrying a new crew to replace Foale and Kaleri.

After leak checks are completed to insure a tight seal between Progress and the ISS, Kaleri will open up the ship?s hatch later today so he and Foale can begin unloading its cargo on Sunday. The cargo includes spare parts for environmental systems and a new flex hose to help vent condensation and air from the Destiny Laboratory?s optically pure viewing window. A small leak in an identical flex hose was found to have caused a slight pressure decay in the ISS earlier this month.

Information on the crew’s activities aboard the Space Station, future launch dates, as well as Station sighting opportunities from anywhere on the Earth, is available on the Internet at:

http://spaceflight.nasa.gov/

Details on Station science operations can be found on an Internet site administered by the Payload Operations Center at NASA’s Marshall Space Flight Center in Huntsville, Ala., at:

http://scipoc.msfc.nasa.gov/

Original Source: NASA News Release

Posted on by Fraser Cain

Are Galaxy Clusters Corrupting Our View of the Big Bang?

Image credit: RAS
In recent years, astronomers have obtained detailed measurements of the cosmic microwave background radiation – the ‘echo’ from the birth of the Universe during the Big Bang.

These results appear to indicate with remarkable precision that our Universe is dominated by mysterious ‘cold dark matter’ and ‘dark energy’. But now a group of UK astronomers has found evidence that the primordial microwave echoes may have been modified or ‘corrupted’ on their 13 billion year journey to the Earth.

The results from a team at the University of Durham, led by Professor Tom Shanks, are based on a new analysis of data from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) satellite.

The team has found that nearby galaxy clusters appear to lie in regions of sky where the microwave temperature is lower than average. This behaviour could be accounted for if the hot gas in the galaxy clusters has interacted with the Big Bang photons as they passed by and corrupted the information contained in this echo of the primordial fireball. Russian physicists R. A. Sunyaev and Ya. B. Zeldovich predicted such an effect in the early 1970’s, shortly after the discovery of the cosmic microwave background radiation.

This Sunyaev-Zeldovich effect has previously been seen in the cases of detailed observations of the microwave background in the vicinity of a few rich galaxy clusters and the WMAP team themselves have reported seeing the effect in their own data, close to cluster centres.

Now the Durham team has found evidence that hot gas in the clusters may influence the microwave background maps out to a radius of nearly 1 degree from the galaxy cluster centres, a much larger area than previously detected. This suggests that the positions of “clusters of clusters” or “superclusters” may also coincide with cooler spots in the pattern of microwave background fluctuations.

“The photons in the microwave background radiation are scattered by electrons in nearby clusters,” said Professor Shanks. “This causes important changes to the radiation by the time it reaches us.”

“If the galaxy clusters located several billion light years from Earth also have the same effect, then we must consider whether it is necessary to modify our interpretation of the satellite maps of the microwave background radiation.”

If the Durham result is confirmed, then the consequences for cosmology could be highly significant. The signature for dark energy and dark matter lies in the detailed structure of the ripples detected in the microwave background, tiny temperature variations that were created at a time when the radius of the Universe was a thousand times smaller than it is today.

If this primordial pattern has been corrupted by processes taking place in the recent past, long after galaxies and galaxy clusters formed, then it will, at best, complicate the interpretation of the microwave echo and, at worst, begin to undermine the previous evidence for both dark energy and cold dark matter.

“The power of this wonderful WMAP data is that it indicates that interpreting the microwave background ‘echo’ may be less straightforward than previously thought,” said team member Sir Arnold Wolfendale (previously Astronomer Royal).

The WMAP team has already reported that their measurements of the Big Bang’s microwave echo may have been compromised by the process of galaxy formation at an intermediate stage in the Universe’s history. They presented evidence that gas heated by first-born stars, galaxies and quasars may have also corrupted the microwave signal when the Universe was 10 or 20 times smaller than at the present day. Thus both the WMAP and Durham results suggest that the microwave echo of the Big Bang may have had to come through many more obstacles on its journey to the Earth than had previously been thought, with consequent possible distortion of the primordial signal.

“Our results may ultimately undermine the belief that the Universe is dominated by an elusive cold dark matter particle and the even more enigmatic dark energy,” said Professor Shanks.

Although the observational evidence for the standard model of cosmology remains strong, the model does contain very uncomfortable aspects. These arise first because it is based on two pieces of “undiscovered physics” – cold dark matter and dark energy – neither of which has been detected in the laboratory. Indeed, the introduction of these two new components greatly increases the complication of the standard Big Bang inflationary model.

The problems of dark energy run particularly deep: for example, its observed density is so small that it may be quantum mechanically unstable. It also creates problems for the theories of quantum gravity, which suggest that we may live in a Universe with 10 or 11 dimensions, all of them shrunk, with the exceptions of three in space and one in time.

Many theorists would therefore like an escape route from today’s standard model of cosmology and it remains to be seen how far these observations discussed by the Durham group will go in this direction. But if correct, they suggest that the rumours that we are living in a “New Era of Precision Cosmology” may prove to be premature!

Original Source: RAS News Release

Posted on by Mark Mortimer

Interview with Michael Benson

Michael Benson, author of Beyond: Visions of the Interplanetary Probes (read Universe Today’s review) took some time from his busy schedule, and nasty cold, to answer some of our questions about his book and interest in astronomy and space exploration. Benson was interviewed by Mark Mortimer.

Universe Today: You say this book is the cumulation of sifting through tens of thousands of image files on computers. What was your selection criteria for the few that made it into the book?

Michael Benson: Well, to start off with, the jaw-drop factor, of course. Stuff that was incredible, I tried my best to get in. After that, though, of course you have the inevitable limitations of the book medium, with its fixed number of pages, plus then I had to divide the solar system up into chapters and try to give each one at least its due if not more, pretty soon I realized I had to winnow the available images down to not as many as I would have liked. And then there was the color versus B&W question — I wanted to get in as many good color shots as I could, though I have a real weakness for black and white photography. Essentially, though, whatever really made me gaze in amazement got in. I have to say, though, that I have a lot of really first-rate processed pictures on my hard drive that I’d love to use elsewhere sometime. Some of it has never been seen before, except for by a small cadre of planetary scientists, and then usually in black and white.

UT: As an artist did you feel like an outsider when discussing these images or did you feel like a member of the group of technicians?

MB: Neither. I always approached them as an aesthetic challenge — how to get them to “pop” — to reveal that they weren’t shot through a digitized grid but through optically pure glass, as it were. And much of the work behind getting them to the right place was technical — using photoshop or other programs — but this is also the tool of a photographer, or ‘artist’ if you will. And even when working with Dr. Paul Geissler, who is an eminent planetary scientist and remote imaging expert, I didn’t feel like an outsider — we had a good collaboration — nor like I belonged to some group of techies either. (I don’t think he feels like the latter either, come to think of it, though he recently took a job at the US Geological Survey — which makes highly accurate maps of all the planets based on space imaging! Which is about as technical as it gets.)

UT: How would you compare the artistic qualities and values of colour to black and white in this medium?

MB: I like both for different reasons. It also depends on the planetary body being represented, to an extent. Black and white pictures of Jupiter’s implacably volcanic, sulphurously yellow-orange moon Io, for example, practically don’t make any sense in a book of this type. They make perfect sense when it comes to conducting science, but would’ve been a bit hard to justify having them in my book, given that Io is by far the most lurid object in the Solar System. And by the same token Europa, Io’s closest neighboring moon, which is a spherical iceberg of fissured, chaotic ice, doesn’t really need to be in color — though it also looks awesome in color. But you get the essence of its story in black and white, if I can put it that way. (Though part of that essence is in fact its mystery — what’s going on under that global ice-cap?)

UT: Do you have a favourite/most photogenic planet? For example Venus seems to be heavily weighed in the book.

MB: Actually, Venus gets fewer pages than either Mars or Jupiter. Jupiter may be the most complex and compelling, though Saturn is a close second, because of its perfect rings. Saturn could scarcely be _more_ photogenic — we’re very lucky to have it in the solar system, because it shows what cosmic perfection really is. And as for Jupiter, as I said in my book, it’s a solar system in miniature — it’s endlessly fascinating and kinetic. The last quality is hard to show with stills, but not impossible.

UT: How were you able to convince a publisher to go for a book of images freely available on the web?

MB: Many of the images were available in raw form at specialized planetary science sites, not “freely available,” in the sense that they required substantial processing and mosacking, rendering into color or what have you. Plus even the images that are more readily available — for example, at NASA’s outreach site A Planetary Photojournal — still required substantial processing, most of them, to get them to work at the resolution quality we have available on the page, as opposed to the screen, where lower resolutions still work.

But the premise of the question is a bit flawed. Publishers are delighted if they can base a book on public domain images, because then they don’t have to pay for it!

UT: Considering the forward, do you think a living carbon based life form will explore our solar system? Other star systems? Do you think humans will do this?

MB: I do. We suffer a bit of temporal tunnel vision as a species. Even if we don’t do it for a hundred or two hundred years in the case of the solar system — and much later for the stars — I still think we’ll do it. Our current hesitation about it has to do with the sluggish pace of crewed exploration after Apollo and also the sense that the environments are so hostile that it might not be desirable to do it. But technology will march onwards and make these such things easier. And then, as soon as it is possible for tourists to actually go to, for example, Jupiter, there will be a huge rush to go there. Or Mars, of course. Or the Moon…

UT: Considering the afterward, where do you think people fit into the universal schema of things?

MB: Oh, I tend to agree with Ren — Lawrence Weschler — that for now at least we seem to be the only creatures that can experience that sense of awe that is ultimately one of the roots of our sentience. My discussion with him had to do with whether machines could ever experience this. I believe one day they will, he’s not so sure. Wasn’t it Asimov who, when asked if he really believed machines would one day think, said “well, I’m a machine, and I think”?

But in the end I think Ren’s daughter Sara is right in saying that the universe in a sense needs us, because we are capable of appreciating its beauty. Another way of putting it, I suppose, is that we are one of the ways in which the universe can appreciate its own splendor. And of course we are pieces of work ourselves, just to coin a phrase!

UT: No 3D images are in the book though we are presently getting some from Mars. What is your opinion of the artistic value of 3D images for this subject and media?

MB: Well, as someone who has barely pried my 3-D glasses of my nose for the last couple weeks, as I peer in fascination at the images from the Spirit and Opportunity rovers, I don’t know how objective I can be on the question. I really like it — though more for that “you are there” sensation than for aesthetic reasons I suppose. But there is no reason why 3-D images can’t be savored for their aesthetic qualities as well. I’ll be able to answer with more conviction on the question after this whole rover experiment is over, because there will really be many thousands of 3-D pictures to go through by then, and no doubt some of them will work on the multiple levels required to be considered art. So the jury — not that I consider myself a jury — is out on the question, but not for too long. Personally, I’d love to see a purple-orange cactus appear on the lip of a crater one of these days — though the artistic qualities of the shot will be the last thing on anyone’s mind if that happens!