Amateur photographer John Chumack took this picture of Spiral Galaxy NGC-253, which is located in the constellation of Sculptor. The telescope was a Takahashi Epsilon 250mm and ST8XE CCD camera, on a Software Bisque Paramount ME, taken on Mount Joy, New Mexico, New Mexico Skies Resort. John operated the telescope remotely from Dayton, Ohio using Arnie Rosner’s Rent-A-Scope setup. John has been imaging the sky for 2 decades, and has an amazing collection of pictures at his website: Galactic Images. If you’re an amateur astrophotographer, visit the Universe Today forum and post your pictures, we might feature it in the newsletter.
Life Might Have Started in Fresh Water
A geomicrobiologist at Washington University in St. Louis has proposed that evolution is the primary driving force in the early Earth’s development rather than physical processes, such as plate tectonics.
Carrine Blank, Ph.D., Washington University assistant professor of geomicrobiology in the Department of Earth & Planetary Sciences in Arts & Sciences, studying Cyanobacteria – bacteria that use light, water, and carbon dioxide to produce oxygen and biomass – has concluded that these species got their start on Earth in freshwater systems on continents and gradually evolved to exist in brackish water environments, then higher salt ones, marine and hyper saline (salt crust) environments.
Cyanobacteria are organisms that gave rise to chloroplasts, the oxygen factory in plant cells. A half billion years ago Cyanobacteria predated more complex organisms like multi-cellular plants and functioned in a world where the oxygen level of the biosphere was much less than it is today. Over their very long life span, Cyanobacteria have evolved a system to survive a gradually increasing oxidizing environment, making them of interest to a broad range of researchers.
Blank is able to draw her hypothesis from family trees she is drawing of Cyanobacteria. Her observations are likely to incite debate among biologists and geologists studying one of Earth’s most controversial eras – approximately 2.1 billion years ago, when cyanobacteria first arose on the Earth. This was a time when the Earth’s atmosphere had an incredible, mysterious and inexplicable rise in oxygen, from extremely low levels to 10 percent of what it is today. There were three – some say four – global glaciations, and the fossil record reflects a major shift in the number of organisms metabolizing sulfur and a major shift in carbon cycling.
“The question is: Why?” said Blank.
“My contribution is the attempt to find evolutionary explanations for these major changes. There were lots of evolutionary movements in Cyanobacteria at this time, and the bacteria were making an impact on the Earth’s development. Geologists in the past have been relying on geological events for transitions that triggered change, but I’m arguing that a lot of these things could be evolutionary.”
Blank presented her research at the 2004 annual meeting of the Geological Society of America, held, Nov. 7-10 in Denver.
Blank’s finding that Cyanobacteria emerged first in fresh water lakes or streams is counterintuitive.
“Most people have the assumption that Cyanobacteria came out of a marine environment – after all, they are still important to marine environments today, so they must always have been,” Blank said. “When Cyanobacteria started to appear, there was no ozone shield, so UV light would have killed most things. They either had to have come up with ways to deal with the UV light – and there is evidence that they made UV-absorbing pigments – or find ways of growing under sediments to avoid the light.”
To study the evolution of Cyanobacteria, Blank drew up a backbone tree using multiple genes from whole genome sequences. Additional species were added to the tree using ribosomal RNA genes. Morphological characters, for instance, the presence or absence of a sheath, unicellular or filamentous growth, the presence or absence of heterocysts ? a thick-walled cell occurring at intervals ? were coded and mapped on the tree. The distribution of traits was compared with those found in the fossil record.
Cyanobacteria emerging some two billion years ago were becoming complex microbes that had larger cell diameters than earlier groups – at least 2.5 microns. Blank’s tree shows that several morphological traits arose independently in multiple lines, among them a sheath structure, filamentous growth, the ability to fix nitrogen, thermophily (love of heat), motility and the use of sulfide as an electron donor.
“We will need lots of analyses of the micro-fossil record by serious paleobiologists to see how sound this hypothesis is,” Blank said. “This time frame is one of the biggest puzzles for biologists and geologists alike. A huge amount of things are happening then in the geological record.”
Original Source: WUSTL News Release
Mighty Ariane 5 Readied for Launch
Preparations are well underway for the qualification flight of Europe?s latest launcher, the Ariane 5 ECA, from Europe’s Spaceport in French Guiana. The launch window opens on the evening of 12 February at 16:49 (20:49 CET) and will extend until 18:10 (22:10 CET).
Ariane 5 ECA will be able to place heavy payloads of up to 10 tonnes into geostationary transfer orbit (GTO) in comparison to the 6-tonne payloads placed into GTO by the Ariane 5 Generic launchers. The increased performance of the Ariane 5 ECA is due to two main differences:
* a more powerful Vulcain-2 first stage engine developed from the Ariane 5 generic Vulcain 1 engine
* a cryogenic upper stage (ESCA) using the tried and tested Ariane 4 HM7B engine that made over 130 successful launches
Since the failure of the first Ariane 5 ECA Flight in December 2002, the Vulcain-2 nozzle extension has been redesigned and tested, and an exhaustive review of the whole launcher has been conducted.
Flight 164 will carry three payloads on its journey into space:
* an XTAR-EUR telecommunications satellite: to be placed into GTO
* Sloshsat-FLEVO, an experimental mini-satellite to investigate the dynamics of fluids in weightlessness, jointly developed by ESA and NIVR, the Dutch Agency for Aerospace Programmes: to be placed into GTO
* Maqsat B2 telemetry/video imaging package: to remain mated to the upper stage of the launcher for recording flight data
A successful rehearsal of the entire launch countdown – including final fuelling and countdown but stopping short of ignition – took place on 12 January. This enabled mission team members to validate launch procedures, and test all launcher equipment and ground facilities.
Original Source: ESA News Release
Air Pollution Linked to Growth of Life in Oceans
A surprising link may exist between ocean fertility and air pollution over land, according to Georgia Institute of Technology research reported in the Feb. 16 issue of the Journal of Geophysical Research – Atmospheres. The work provides new insight into the role that ocean fertility plays in the complex cycle involving carbon dioxide and other greenhouse gases in global warming.
When dust storms pass over industrialized areas, they can pick up sulfur dioxide, an acidic trace gas emitted from industrial facilities and power plants. As the dust storms move out over the ocean, the sulfur dioxide they carry lowers the pH (a measure of acidity and alkalinity) level of dust and transforms iron into a soluble form, said Nicholas Meskhidze, a postdoctoral fellow in Professor Athanasios Nenes’ group at Georgia Tech’s School of Earth and Atmospheric Sciences and lead author of the paper “Dust and Pollution: A Recipe for Enhanced Ocean Fertilization.”
This conversion is important because dissolved iron is a necessary micronutrient for phytoplankton – tiny aquatic plants that serve as food for fish and other marine organisms, and also reduce carbon dioxide levels in Earth’s atmosphere via photosynthesis. Phytoplankton carry out almost half of Earth’s photosynthesis even though they represent less than 1 percent of the planet’s biomass.
In research funded by the National Science Foundation, Meskhidze began studying dust storms three years ago under the guidance of William Chameides, Regents’ Professor and Smithgall Chair at Georgia Tech’s School of Earth and Atmospheric Sciences and co-author of the paper.
“I knew that large storms from the Gobi deserts in northern China and Mongolia could carry iron from the soil to remote regions of the northern Pacific Ocean, facilitating photosynthesis and carbon-dioxide uptake,” Meskhidze said. “But I was puzzled because the iron in desert dust is primarily hematite, a mineral that is insoluble in high-pH solutions such as seawater. So it’s not readily available to the plankton.”
Using data obtained in a flight over the study area, Meskhidze analyzed the chemistry of a dust storm that originated in the Gobi desert and passed over Shanghai before moving onto the northern Pacific Ocean. His discovery: When a high-concentration of sulfur dioxide mixed with the desert dust, it acidified the dust to a pH below 2 – the level needed for mineral iron to convert into a dissolved form that would be available to phytoplankton.
Expanding on this discovery, Meskhidze studied how variations in air pollution and mineral dust affect iron mobilization.
Obtaining in-flight data from two different Gobi-desert storms – one occurring on March 12, 2001, and the other on April 6, 2001 — Meskhidze analyzed the pollution content and then modeled the storms’ trajectory and chemical transformation over the North Pacific Ocean. Using satellite measurements, he determined whether there had been increased growth of phytoplankton in the ocean area where the storms passed.
The results were surprising, he said. Although the April storm was a large one, with three sources of dust colliding and traveling as far as the continental United States, there was no increased phytoplankton activity. Yet the March storm, albeit smaller, significantly boosted the production of phytoplankton.
The differing results can be attributed to the concentration of sulfur dioxide existing in dust storms, Meskhidze said. Large storms are highly alkaline because they contain a higher proportion of calcium carbonate. Thus, the amount of sulfur dioxide picked up from pollution is not enough to bring down the pH below 2.
“Although large storms can export vast amounts of mineral dust to the open ocean, the amount of sulfur dioxide required to acidify these large plumes and generate bioavailable iron is about five to 10 times higher than the average springtime concentrations of this pollutant found in industrialized areas of China,” Meskhidze explained. “Yet the percentage of soluble iron in small dust storms can be many orders of magnitude higher than large dust storms.”
So even though small storms are limited in the amount of dust they transport to the ocean and may not cause large plankton blooms, small storms still produce enough soluble iron to consistently feed phytoplankton and fertilize the ocean. This may be especially important for high-nitrate, low-chlorophyll waters, where phytoplankton production is limited because of a lack of iron.
Natural sources of sulfur dioxide, such as volcanic emissions and ocean production, may also cause iron mobilization and stimulate phytoplankton growth. Yet emissions from human-made sources normally represent a larger portion of the trace gas. Also, human-made emission sites may be closer to the storm’s course and have a stronger influence on it than natural sulfur dioxide, Meskhidze said.
This research deepens scientists’ understanding of the carbon cycle and climate change, he added.
“It appears that the recipe of adding pollution to mineral dust from East Asia may actually enhance ocean productivity and, in so doing, draw down atmospheric carbon dioxide and reduce global warming,” Chameides said.
“Thus, China’s current plans to reduce sulfur dioxide emissions, which will have far-reaching benefits for the environment and health of the people of China, may have the unintended consequence of exacerbating global warming,” he added. “This is perhaps one more reason why we all need to get serious about reducing our emissions of carbon dioxide and other greenhouse gases.”
Original Source: Georgia Tech News Release
Diamond Worlds Could Exist
Image credit: NASA
Some extrasolar planets may be made substantially from carbon compounds, including diamond, according to a report presented this week at the conference on extrasolar planets in Aspen, Colorado. Earth, Mars and Venus are “silicate planets” consisting mostly of silicon-oxygen compounds. Astrophysicists are proposing that some stars in our galaxy may host “carbon planets” instead.
“Carbon planets could form in much the same way as do certain meteorites in our solar system, the carbonaceous chondrites,” said Dr. Marc J. Kuchner of Princeton University, making the report in Aspen together with Dr. Sara Seager of the Carnegie Institute of Washington. “These meteorites contain large quantities of carbon compounds such as carbides, organics, and graphite, and even the occasional tiny diamond.” Imagine such a meteorite the size of a planet, and you are picturing a carbon planet.
Planets like the Earth are thought to condense from disks of gas orbiting young stars. In gas with extra carbon or too little oxygen, carbon compounds like carbides and graphite condense out instead of silicates, possibly explaining the origin of carbonaceous chondrites and suggesting the possibility of carbon planets. Any condensed graphite would change into diamond under the high pressures inside the carbon planets, potentially forming diamond layers inside the planets many miles thick.
Some of the already known low- and intermediate-mass extrasolar planets may be carbon planets, which should easily survive at high temperatures near a star if they have the mass of Neptune. Carbon planets would probably consist mostly of carbides, thought they may have iron cores and substanial atmospheres. Carbides are a kind of ceramic used to line the cylinders of motorcycle engines among other things.
The planets orbiting the pulsar PSR 1257+12 are good candidates for carbon planets; they may have formed from the disruption of a star that produced carbon as it aged. So are planets located near the center of the Galaxy, where stars are more carbon-rich than the sun, on average. Slowly, the galaxy as a whole is becoming more carbon-rich; in the future, all planets formed may be carbon planets.
“There’s no reason to think that extrasolar planets will be just like the planets in the solar system.” says Kuchner. “The possibilities are startling.”
Kuchner added, “NASA’s future Terrestrial Planet Finder (TPF) mission may be able to spot these planets.” The spectra of these planets should lack water, and instead reveal carbon monoxide, methane, and possibly long-chain carbon compounds synthesized photochemically in their atmospheres. The surfaces of carbon planets may be covered with a layer of long-chain carbon compounds–in other words, something like crude oil or tar.
The first TPF telescope, an optical telescope several times the size of the Hubble Space Telescope is scheduled to launch in 2015. The TPF missions are designed to search for planets like the Earth and determine whether they might be suitable for life.
Original Source: NASA Astrobiology Story
Black Holes Manage Galactic Growth
Using a new computer model of galaxy formation, researchers have shown that growing black holes release a blast of energy that fundamentally regulates galaxy evolution and black hole growth itself. The model explains for the first time observed phenomena and promises to deliver deeper insights into our understanding of galaxy formation and the role of black holes throughout cosmic history, according to its creators. Published in the Feb. 10 issue of Nature, the results were generated by Carnegie Mellon University astrophysicist Tiziana Di Matteo and her colleagues while at the Max Planck Institut fur Astrophysik in Germany. Di Matteo?s collaborators include Volker Springel at Max-Planck Institut for Astrophysics and Lars Hernquist at Harvard University.
“In recent years, scientists have begun to appreciate that the total mass of stars in today?s galaxies corresponds directly to the size of a galaxy?s black hole, but until now, no one could account for this observed relationship,” said Di Matteo, assistant professor of physics at Carnegie Mellon. “Using our simulations has given us a completely new way to explore this problem.”
The key to the researchers? breakthrough was incorporating calculations for black hole dynamics into a computational model of galaxy formation.
As galaxies formed in the early universe, they likely contained small black holes at their centers. In the standard scenario of galaxy formation, galaxies grow by coming together with one another by the pull of gravity. In the process, the black holes at their center merge together and quickly grow to reach their observed masses of a billion times that of the Sun; hence, they are called supermassive black holes. Also at the time of merger, the majority of stars form from available gas. Today?s galaxies and their central black holes must be the result of a series of such events.
Di Matteo and her colleagues simulated the collision of two nascent galaxies and found that when the two galaxies came together, their two supermassive black holes merged and initially consumed the surrounding gas. But this activity was self-limiting. As the remnant galaxy?s supermassive black hole sucked up gas, it powered a luminescent state called a quasar. The quasar energized the surrounding gas to such a level that it was blown away from the vicinity of the supermassive black hole to the outside of the galaxy. Without nearby gas, the galaxy?s supermassive black hole could not “eat” to sustain itself and became dormant. At the same time, gas was no longer available to form any more stars.
“We?ve discovered that the energy released by black holes during a quasar phase powers a strong wind that prevents material from falling into the black hole,” Springel said. “This process inhibits further black hole growth and shuts off the quasar, just as star formation stops inside a galaxy. As a result, the black hole mass and the mass of stars in a galaxy are closely linked. Our results also explain for the first time why the quasar lifetime is such a short phase compared to the life of a galaxy.”
In their simulations, Di Matteo, Springel and Hernquist found that the black holes in small galaxies self-limit their growth more effectively than in those in larger galaxies. A smaller galaxy contains smaller amounts of gas so that a small amount of energy from the black hole can quickly blow this gas away. In a large galaxy, the black hole can reach a greater size before its surrounding gas is energized enough to stop falling in. With their gas quickly spent, smaller galaxies make fewer stars. With a longer-lived pool of gas, larger galaxies make more stars. These findings match the observed relation between black hole size and the total mass of stars in galaxies.
“Our simulations demonstrate that self-regulation can quantitatively account for observed facts associated with black holes and galaxies,” said Hernquist, professor and chair of astronomy in Harvard?s Faculty of Arts and Sciences. “It provides an explanation for the origin of the quasar lifetime and should allow us to understand why quasars were more plentiful in the early universe than they are today.”
“With these computations, we now see that black holes must have an enormous impact on the way galaxies form and evolve,” Di Matteo said. “The successes obtained so far will allow us to implement these models within larger simulated universes, so that we can understand how large populations of black holes and galaxies influence each other in a cosmological context.”
The team ran their simulations with the extensive computing resources of the Center for Parallel Astrophysical Computing at the Harvard-Smithsonian Center for Astrophysics and at the Rechenzentrum der Max-Planck-Gesellschaft in Garching.
Original Source: Max Planck Institute News Release
Death Star Mimas’ Herschel Crater
Saturn’s moon Mimas has many large craters, but its Herschel crater dwarfs all the rest. This large crater 130 kilometers wide (80 miles) has a prominent central peak, seen here almost exactly on the terminator. This crater is the moon’s most prominent feature, and the impact that formed it probably nearly destroyed Mimas. Mimas is 398 kilometers (247 miles) across.
This view is predominantly of the leading hemisphere of Mimas. The image has been rotated so that north on Mimas is up.
This image was taken with the Cassini spacecraft narrow angle camera on Jan. 16, 2005, at a distance of approximately 213,000 kilometers (132,000 miles) from Mimas and at a Sun-Mimas-spacecraft, or phase, angle of 84 degrees. Resolution in the original image was about 1.3 kilometers (0.8 miles) per pixel. A combination of spectral filters sensitive to ultraviolet and polarized light was used to obtain this view. Contrast was enhanced and the image was 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 images visit the Cassini imaging team home page http://ciclops.org .
Original Source: NASA/JPL/SSI News Release
What Did Galileo See?
By the time Galileo took eye to eyepiece in Padua Italy in 1609, he had already begun a life-long quest to understand the natural world around him. At his father’s behest, Gailieo gave up his youthful aspirations to join the Camaldolese Order as a monk and began training in medicine. Before completing his medical studies however, Galileo’s strong interest in the laws of nature (along with a little intercession by one of his teachers in mathematics) overcame his fathers insistence and he embraced mathematics.
Over the next quarter century Galileo made numerous investigations into the mechanics of motion and weight. Early on he was intrigued by Archimedes investigations into specific gravity and published a work entitled: “La Balancitta” (or “The Little Weight”). Galileo’s bent was as scientific as mathematical, he suggested methods of testing the behavior of falling bodies using inclined planes. (Although it is unlikely that he ever dropped objects from the famed “Leaning Tower of Pisa”.)
By the year 1609 Galileo had spent nearly two decades ensconced as a lecturer on mathematics and physical sciences at the University of Padua. He is said to have described this period as one of the most personally fulfilling years of his life. But the quiet joys of teaching and raising a family of three children were poised for change. And that change came in the form of a fateful letter describing a spyglass demonstrated by a Dutchman visiting Venice (located some 40 kms west of the university).
Based on a scant description of the spyglass workings, Galileo concluded that its main principle was that of refraction. Obtaining “off-the-shelf” lenses normally for spectacle use, he soon possessed a 4x instrument and it wasn’t long thereafter that he had personally ground a lens set and crafted a telescope of twice that magnification. By the Spring of 1610, Galileo had published the first telescopic “observing reports” describing denizens of the night sky. And in that report (Sidereus Nuncius – The Starry Messenger) Galileo himself lists a few of his most startling discoveries:
“With the aid of this new instrument one looks upon the face of the Moon, the expanse of the Milky Way, innumerable fixed stars, faint nebulosities and asterisms, and the four wandering stars attending Jupiter never before seen.”-1
Recognizing the significance of these discoveries Galileo goes on to say:
“Great things embodying the spirit of truth based on observation and contemplation of nature do I propose in this short treatise. Large, I say, and for the clarification of truth, based on an innovation never heard throughout the centuries, and finally I extoll the instrument by which means these same things have been revealed to our perception.”
There can be no doubt that Galileo’s early adoption of the recently invented spyglass for astronomical purposes marked a major departure toward the way we now view the world. For before Galileo’s era the heavens and the Earth were not in accord. The bulk of the thinking going on prior to Galileo was scholastic in nature. Truth depended on the words of the ancients – words which carried greater weight of authority than natural law and behavior. It was the era of faith – not science – that Galileo was born into. But his observations built a bridge between Terrum et Coelum. Earth and sky became part of a single natural order. The telescope could demonstrate to anyone with an open mind that there was more to all things than could be conceived of by the great minds of the past. Nature had begun to instruct the hearts and minds of humanity…
But let us speak no more of Earth-shaking events. What did Galileo actually see in the early months of the year 1610?
Lacking a background in Latin is no hindrance to furthering our investigation, for “the Starry Messenger” himself left many fine sketches (a few which are seen in the above composite image).
Of course, any amateur astronomer of the today can do no better than to begin with the Moon. Using a telescope is no easy matter. Sweeping the sky unsteadily at high magnifications to find anything in the heavens can be very frustrating to the neophyte to our High Art and Science. Of course, Galileo’s first telescope was very low power and this simplified things. But his later instruments always included a second smaller “finder scope” to simplify astro-navigation. Here are some of Galileo’s descriptions of the Moon:
“Most beautiful and admirable is it to see the Moon’s luminous form,… At nearly thirty diameters – some 900 times greater in region – anyone can perceive that the Moon is not covered with a smooth and uniform surface but in fact reveals great mountainous shelves, deep cavities, and gorges just like those of the Earth.”
Even during the winter the Milky Way can be seen – a faint gossamer of light attending Cassiopeia and Perseus to the north then plummeting south east of Orion – the Hunter, into Monoceros – the Unicorn. Again The Starry Messenger speaks:
“Moreover let us not underestimate the questions surrounding the Milky Way. For it has revealed to the senses its essence (through the turning of our instrument upon it). And in so doing out of its cloudy substance numerous stars are called forth.”
But in terms of Galileo’s own estimation his observations of the four Jupiterean satellites evoked the greatest of significances:
“By far and exceeding every other wonder, and mainly promoted for the contemplation of all astronomers and philosophers, is the discovery of four wandering stars. For I propose that they – like Venus and Mercury around the Sun – have revolutions around a conspicuous star among the known wanderers. And in their lesser wanderings they may precede the greater – sometimes before it and sometimes after – never going beyond some pre-determined limits.”
Galileo also went on to detect sun spots and the phases of Venus. The Venusian phases, in particular conclusively demonstrated the heliocentrism conceived by Copernicus and mathematically described by Johan Kepler of Galileo’s own time and correspondence.
Of course Galileo was large enough in his perception to realize that these few initial discoveries were but only the beginnings of a beginning for the telescope as an instrument and astronomy as a whole for he goes on to say:
“Perhaps other miraculous things from both myself and others will be discovered in the future aided by this instrument…”
Galileo was wrong – there was no “perhaps” about it…
-1 This and later quotations ascribed to Galileo are re-interpretations of an Italian to English Babelfish translation of Siderius Nuncius by the author.
About The Author:
Inspired by the early 1900’s masterpiece: “The Sky Through Three, Four, and Five Inch Telescopes”, Jeff Barbour got a start in astronomy and space science at the age of seven. Currently Jeff devotes much of his time observing the heavens and maintaining the website Astro.Geekjoy.
Huygens Wind Data Released
Image credit: ESA
Using a global network of radio telescopes, scientists have measured the speed of the winds faced by Huygens during its descent through the atmosphere of Titan.
This measurement could not be done from space because of a configuration problem with one of Cassini?s receivers. The winds are weak near the surface and increase slowly with altitude up to about 60 km, becoming much rougher higher up where significant vertical wind shear may be present.
Preliminary estimates of the wind variations with altitude on Titan have been obtained from measurements of the frequency of radio signals from Huygens, recorded during the probe?s descent on 14 January 2005. These ?Doppler? measurements, obtained by a global network of radio telescopes, reflect the relative speed between the transmitter on Huygens and the receiver on the Earth.
Winds in the atmosphere affected the horizontal speed of the probe?s descent and produced a change in the frequency of the signal received on Earth. This phenomenon is similar to the commonly heard change in pitch of a siren on a speeding police car.
Leading the list of large radio antennas involved in the programme were the NRAO Robert C. Byrd Green Bank Telescope (GBT) in West Virginia, USA, and the CSIRO Parkes Radio Telescope in Australia. Special instrumentation designed for detection of weak signals was used to measure the ?carrier? frequency of the Huygens radio signal during this unique opportunity.
The initial detection, made with the ?Radio Science Receivers? on loan from NASA?s Deep Space Network, provided the first unequivocal proof that Huygens had survived the entry phase and had begun its radio relay transmission to Cassini.
The very successful signal detection on Earth provided a surprising turnabout for the Cassini-Huygens Doppler Wind Experiment (DWE), whose data could not be recorded on the Cassini spacecraft due to a commanding error needed to properly configure the receiver.
?Our team has now taken a significant first step to recovering the data needed to fulfil our original scientific goal, an accurate profile of Titan’s winds along the descent trajectory of Huygens,? said DWE?s Principal Investigator Dr Michael Bird (University of Bonn, Germany).
The ground-based Doppler measurements were carried out and processed jointly by scientists from the NASA Jet Propulsion Laboratory (JPL, USA) and the Joint Institute for VLBI in Europe (JIVE, The Netherlands) working within the DWE team.
Winds on Titan are found to be flowing in the direction of Titan’s rotation (from west to east) at nearly all altitudes. The maximum speed of roughly 120 metres per second (430 km/h) was measured about ten minutes after the start of the descent, at an altitude of about 120 km. The winds are weak near the surface and increase slowly with altitude up to about 60 km.
This pattern does not continue at altitudes above 60 km, where large variations in the Doppler measurements are observed. Scientists believe that these variations may arise from significant vertical wind shear. That Huygens had a rough ride in this region was already known from the science and engineering data recorded on board Huygens.
?Major mission events, such as the parachute exchange about 15 minutes into the atmospheric flight and impact on Titan at 13:45 CET, produced Doppler signatures that we can clearly identify in the data,? Bird said.
At present, there exists an approximately 20-minute interval with no data between the measurements at GBT and Parkes. This gap in Doppler coverage will eventually be closed by data from other radio telescopes which are presently being analysed. In addition, the entire global set of radio telescopes performed Very Long Baseline Interferometry (VLBI) recordings of the Huygens signal to determine the probe?s precise position during the descent.
?This is a stupendous example of the effectiveness of truly global scientific co-operation,? said Jean-Pierre Lebreton, ESA Huygens Project Scientist. ?By combining the Doppler and VLBI data we will eventually obtain an extremely accurate three-dimensional record of the motion of Huygens during its mission at Titan,? he concluded.
Original Source: ESA News Release
Northern Saturn is a Little Blue
Colorful new images from the Cassini spacecraft show that Saturn’s northern hemisphere has a case of the blues.
In the first image, the icy moon Mimas is set against a dazzling and dramatic portrait of Saturn’s azure northern hemisphere and the shadows of its rings. A second image shows Saturn’s northern polar region is a dim blue.
The new images are available at http://www.nasa.gov/cassini, http://saturn.jpl.nasa.gov and http://ciclops.org.
The blue color of Saturn’s northern latitudes may to be linked to the apparently cloud-free nature of the upper atmosphere there. A precise understanding of the phenomenon may come from further study by Cassini imaging scientists.
In the first of these colorful views, Mimas moves in its orbit against the blue backdrop of Saturn’s atmosphere, which is draped by sweeping shadows cast by the rings. A few large craters are visible on Mimas, giving the icy moon a dimpled appearance.
The second view shows Saturn’s northern polar region, where shadows cast by the rings surrounding the pole appear as dark bands. The ring shadows at higher latitudes correspond to locations on the ring plane that are farther from the planet – in other words, the northernmost ring shadow in this view is cast by the outer edge of Saturn’s A ring. Spots of bright clouds also are visible throughout the region.
The view of Saturn and Mimas was taken by the Cassini spacecraft’s narrow angle camera on Jan. 18, 2005, at a distance of approximately 1.4 million kilometers (870,000 miles) from Saturn. The view of Saturn’s northern polar region was taken with Cassini’s wide angle camera on Dec. 14, 2004, at a distance of 719,200 kilometers (446,900 miles) from Saturn.
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 and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.
Original Source: NASA/JPL News Release