vendredi 24 janvier 2014

Several Spacecraft Take Aim At Nearby Supernova





















NASA/ESA - Hubble Space Telescope patch / NASA - Chandra X-ray Observatory patch / NASA - NuStar Mission patch / NASA - Fermi Gamma-ray Space Telescope logo / NASA - Swift Mission patch.

Jan. 24, 2014

An exceptionally close stellar explosion discovered on Jan. 21 has become the focus of observatories around and above the globe, including several NASA spacecraft. The blast, designated SN 2014J, occurred in the galaxy M82 and lies only about 12 million light-years away. This makes it the nearest optical supernova in two decades and potentially the closest type Ia supernova to occur during the life of currently operating space missions.

To make the most of the event, astronomers have planned observations with the NASA/ESA Hubble Space Telescope and NASA's Chandra X-ray Observatory, Nuclear Spectroscopic Telescope Array (NuSTAR), Fermi Gamma-ray Space Telescope, and Swift missions.

As befits its moniker, Swift was the first to take a look. On Jan. 22, just a day after the explosion was discovered, Swift's Ultraviolet/Optical Telescope (UVOT) captured the supernova and its host galaxy.

Fig.1
Fig.2

Images above: These Swift UVOT images show M82 before (Fig.1) and after the new supernova (Fig.2). The pre-explosion view combines data taken between 2007 and 2013. The view showing SN 2014J (arrow) merges three exposures taken on Jan. 22, 2014. Mid-ultraviolet light is shown in blue, near-UV light in green, and visible light in red. The image is 17 arcminutes across, or slightly more than half the apparent diameter of a full moon. Image Credit: NASA/Swift/P. Brown, TAMU.

Remarkably, SN 2014J can be seen on images taken up to a week before anyone noticed its presence. It was only when Steve Fossey and his students at the University of London Observatory imaged the galaxy during a brief workshop that the supernova came to light.

"Finding and publicizing new supernova discoveries is often the weak link in obtaining rapid observations, but once we know about it, Swift frequently can observe a new object within hours," said Neil Gehrels, the mission's principal investigator at NASA's Goddard Space Flight Center in Greenbelt, Md.

Although the explosion is unusually close, the supernova's light is attenuated by thick dust clouds in its galaxy, which may slightly reduce its apparent peak brightness.

"Interstellar dust preferentially scatters blue light, which is why Swift's UVOT sees SN 2014J brightly in visible and near-ultraviolet light but barely at all at mid-ultraviolet wavelengths," said Peter Brown, an astrophysicist at Texas A&M University who leads a team using Swift to obtain ultraviolet observations of supernovae.


Image above: Swift UVOT images shows M82 before and after the new supernova. The pre-explosion view combines data taken between 2007 and 2013. The view showing SN 2014J (arrow) merges three exposures taken on Jan. 22, 2014. Mid-ultraviolet light is shown in blue, near-UV light in green, and visible light in red. Image Credit: NASA/Swift/P. Brown, TAMU.

However, this super-close supernova provides astronomers with an important opportunity to study how interstellar dust affects its light. As a class, type Ia supernovae explode with remarkably similar intrinsic brightness, a property that makes them useful "standard candles" -- some say "standard bombs" -- for exploring the distant universe.

Brown notes that X-rays have never been conclusively observed from a type Ia supernova, so a detection by Swift's X-ray Telescope, Chandra or NuSTAR would be significant, as would a Fermi detection of high-energy gamma rays.

A type Ia supernova represents the total destruction of a white dwarf star by one of two possible scenarios. In one, the white dwarf orbits a normal star, pulls a stream of matter from it, and gains mass until it reaches a critical threshold and explodes. In the other, the blast arises when two white dwarfs in a binary system eventually spiral inward and collide. 


Animation above: This animated GIF of Swift UVOT images shows M82 before and after the new supernova. The pre-explosion view combines data taken between 2007 and 2013. The view showing SN 2014J merges three exposures taken on Jan. 22, 2014. Mid-ultraviolet light is shown in blue, near-UV light in green, and visible light in red. Animation Credit: NASA/Swift/P. Brown, TAMU.

Either way, the explosion produces a superheated shell of plasma that expands outward into space at tens of millions of miles an hour. Short-lived radioactive elements formed during the blast keep the shell hot as it expands. The interplay between the shell's size, transparency and radioactive heating determines when the supernova reaches peak brightness. Astronomers expect SN 2014J to continue brightening into the first week of February, by which time it may be visible in binoculars.

M82, also known as the Cigar Galaxy, is located in the constellation Ursa Major and is a popular target for small telescopes. M82 is undergoing a powerful episode of star formation that makes it many times brighter than our own Milky Way galaxy and accounts for its unusual and photogenic appearance.

Related Links:

Download high-resolution images from NASA Goddard's Science Visualization Studio: http://svs.gsfc.nasa.gov/goto?11459

Supernova in Messier 82 Was Discovered by UCL Students: http://www.ucl.ac.uk/maps-faculty/maps-news-publication/maps1405/

List of young supernovae observed by NASA's Swift: http://people.physics.tamu.edu/pbrown/SwiftSN/swift_sn.html

"Dying Supergiant Stars Implicated in Hours-long Gamma-Ray Bursts" (04.16.2013): http://www.nasa.gov/mission_pages/swift/bursts/supergiant-stars.html

"NASA's Swift, Chandra Explore a Youthful 'Star Wreck'" (03.15.13): http://www.nasa.gov/mission_pages/swift/bursts/star-wreck.html

"NASA's Swift Narrows Down Origin of Important Supernova Class" (03.20.12): http://orbiterchspacenews.blogspot.ch/search?q=NASA%27s+Swift+Narrows+Down+Origin+of+Important+Supernova+Class

"Fermi Detects 'Shocking' Surprise from Supernova's Little Cousin" (08.12.10): http://orbiterchspacenews.blogspot.ch/search?q=Fermi+Detects+%27Shocking%27+Surprise+from+Supernova%27s+Little+Cousin

Images (mentioned), Animation (mentioned), Text, Credits: NASA's Goddard Space Flight Center / Francis Reddy.

Greetings, Orbiter.ch

NASA's Opportunity Rover Yields More Data on Changes to Mars' Environment











NASA - Mars Exploration Rover (MER-B) "Opportunity" patch.

Jan. 24, 2014

New findings from rock samples collected and examined by NASA's Mars Exploration Rover Opportunity have confirmed an ancient wet environment that was milder and older than the acidic and oxidizing conditions told by rocks the rover examined previously.

In this week's edition of the journal Science, Opportunity Deputy Principal Investigator Ray Arvidson, a professor at Washington University in St. Louis, writes in detail about the discoveries made by the rover and how these discoveries have shaped our knowledge of the planet. According to Arvidson and others on the team, the latest evidence from Opportunity is landmark.

"These rocks are older than any we examined earlier in the mission, and they reveal more favorable conditions for microbial life than any evidence previously examined by investigations with Opportunity," said Arvidson.

While the Opportunity team celebrates the rover's 10th anniversary on Mars, they also look forward to what discoveries lie ahead and how a better understanding of Mars will help advance plans for human missions to the planet in the 2030s.


Image above: NASA's Mars Exploration Rover Opportunity recorded the component images for this self-portrait about three weeks before completing a decade of work on Mars. The rover's panoramic camera (Pancam) took the images during the interval Jan. 3, 2014, to Jan. 6, 2014. Image Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

Opportunity's original mission was to last only three months. On the day of its 10th anniversary on the Red Planet, Opportunity is examining the rim of the Endeavour Crater. It has driven 24 miles (38.7 kilometers) from where it landed on Jan. 24, 2004.  The site is about halfway around the planet from NASA's latest Mars rover, Curiosity.

To find rocks for examination, the rover team at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., steered Opportunity in a loop, scanning the ground for promising rocks in an area of Endeavour's rim called Matijevic Hill. The search was guided by a mineral-mapping instrument on NASA's Mars Reconnaissance Orbiter (MRO), which did not arrive at Mars until 2006, long after Opportunity's mission was expected to end.

Beginning in 2010, the mapping instrument, called the Compact Reconnaissance Imaging Spectrometer for Mars, detected evidence on Matijevic Hill of a clay mineral known as iron-rich smectite. The Opportunity team set a goal to examine this mineral in its natural context -- where it is found, how it is situated with respect to other minerals and the area's geological layers -- a valuable method for gathering more information about this ancient environment. Researchers believe the wet conditions that produced the iron-rich smectite preceded the formation of the Endeavor Crater about 4 billion years ago.

"The more we explore Mars, the more interesting it becomes. These latest findings present yet another kind of gift that just happens to coincide with Opportunity's 10th anniversary on Mars," said Michael Meyer, lead scientist for NASA's Mars Exploration Program. "We're finding more places where Mars reveals a warmer and wetter planet in its history. This gives us greater incentive to continue seeking evidence of past life on Mars."

Opportunity has not experienced much change in health in the past year and the vehicle remains a capable research partner for the team of scientists and engineers who plot each day's activities to be carried out on Mars.

Artist's view of the Mars Exploration Rover (MER-B) "Opportunity". Image Credit: NASA/JPL-Caltech

"We're looking at the legacy of Opportunity's first decade this week, but there's more good stuff ahead," said Steve Squyres of Cornell University, Ithaca, N.Y., the mission's principal investigator. "We are examining a rock right in front of the rover that is unlike anything we've seen before. Mars keeps surprising us, just like in the very first week of the mission."

JPL manages the Mars Exploration Rover Project for NASA's Science Mission Directorate in Washington. Opportunity's twin, Spirit, which worked for six years, and their successor, Curiosity, also contributed valuable information about the diverse watery environments of ancient Mars, from hot springs to flowing streams. NASA's Mars orbiters Odyssey and MRO study the whole planet and assist the rovers.

"Over the past decade, Mars rovers have made the Red Planet our workplace, our neighborhood," said John Callas, manager of NASA's Mars Exploration Rover Project, which built and operates Opportunity. "The longevity and the distances driven are remarkable. But even more important are the discoveries that are made and the generation that has been inspired."

Special products for the 10th anniversary of the twin rovers' landings, including a gallery of selected images, are available online at: http://mars.nasa.gov/mer10/

For more information about Spirit and Opportunity, visit: http://www.nasa.gov/rovers

You can follow the project on Twitter and on Facebook at: http://twitter.com/MarsRovers and http://www.facebook.com/mars.rovers

Images (mentioned), Text, Credits: NASA / Dwayne Brown / JPL / Guy Webster.


Cheers, Orbiter.ch

NASA Launches Third Generation Communications Satellite











NASA - TDRS-L Mission patch.


Jan. 24, 2014


Image above: NASA's Tracking and Data Relay Satellite L (TDRS-L) launches from Cape Canaveral Air Force Station in Florida on Jan. 23, 2014 aboard a United Launch Alliance Atlas V rocket. Image Credit: NASA/Kim Shiflett.

NASA's Tracking and Data Relay Satellite L (TDRS-L), the 12th spacecraft in the agency's TDRS Project, is safely in orbit after launching at 9:33 p.m. EST Thursday aboard a United Launch Alliance Atlas V rocket from Cape Canaveral Air Force Station in Florida.

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Launch of NASA's New TDRS-L Spacecraft on Atlas V

Ground controllers report the satellite -- part of a network providing high-data-rate communications to the International Space Station, Hubble Space Telescope, launch vehicles and a host of other spacecraft -- is in good health at the start of a three-month checkout by its manufacturer, Boeing Space and Intelligence Systems of El Segundo, Calif. NASA will conduct additional tests before putting TDRS-L into service.

"TDRS-L and the entire TDRS fleet provide a vital service to America’s space program by supporting missions that range from Earth-observation to deep space discoveries," said NASA Administrator Charles Bolden. "TDRS also will support the first test of NASA’s new deep space spacecraft, the Orion crew module, in September. This test will see Orion travel farther into space than any human spacecraft has gone in more than 40 years."

Tracking and Data Relay Satellite Launch Lights Up the Night Sky

The mission of the TDRS Project, established in 1973, is to provide follow-on and replacement spacecraft to support NASA's space communications network. This network provides high data-rate communications. The TDRS-L spacecraft is identical to the TDRS-K spacecraft launched in 2013.

"This launch ensures continuity of services for the many missions that rely on the system every day," said Jeffrey Gramling, TDRS project manager at NASA's Goddard Space Flight Center, Greenbelt, Md.

The TDRS fleet began operating during the space shuttle era with the launch of TDRS-1 in 1983. Of the 11 TDRS spacecraft placed in service to date, eight still are operational. Four of the eight have exceeded their design life.

Boeing Space and Intelligence Systems completed the TDRS-L integration and testing at its satellite factory in El Segundo in November and launch processing began after the spacecraft arrived in Florida Dec. 6.

TDRS-M, the next spacecraft in this series, is on track to be ready for launch in late 2015.

Tracking and Data Relay Satellite L (TDRS-L)

NASA's Space Communications and Navigation Program, part of the Human Exploration and Operations Mission Directorate (HEOMD) at the agency's Headquarters in Washington, is responsible for the space network. The TDRS Project Office at Goddard manages the TDRS development program. Launch management of the launch service for TDRS-L is the responsibility of HEOMD’s Launch Services Program based at the agency's Kennedy Space Center in Florida.  United Launch Alliance provided the Atlas V rocket launch service.

To join the online conversation about TDRS on Twitter, use the hashtag #TDRS.

For more information about TDRS, visit: http://tdrs.gsfc.nasa.gov

To learn more about the many ways to connect and collaborate with NASA, visit: http://www.nasa.gov/connect

NASA / Joshua Buck / Kim Shiflett / Dan Casper / Goddard Space Flight Center / Dewayne Washington.

Greetings, Orbiter.ch

jeudi 23 janvier 2014

Extreme Power of Black Hole Revealed











NASA - Chandra X-ray Observatory patch.

Jan.23, 2014


Astronomers have used NASA's Chandra X-ray Observatory and a suite of other telescopes to reveal one of the most powerful black holes known. The black hole has created enormous structures in the hot gas surrounding it and prevented trillions of stars from forming.

The black hole is in a galaxy cluster named RX J1532.9+3021 (RX J1532 for short), located about 3.9 billion light years from Earth. The image here is a composite of X-ray data from Chandra revealing hot gas in the cluster in purple and optical data from the Hubble Space Telescope showing galaxies in yellow. The cluster is very bright in X-rays implying that it is extremely massive, with a mass about a quadrillion - a thousand trillion - times that of the sun. At the center of the cluster is a large elliptical galaxy containing the supermassive black hole.

The large amount of hot gas near the center of the cluster presents a puzzle. Hot gas glowing with X-rays should cool, and the dense gas in the center of the cluster should cool the fastest. The pressure in this cool central gas is then expected to drop, causing gas further out to sink in towards the galaxy, forming trillions of stars along the way. However, astronomers have found no such evidence for this burst of stars forming at the center of this cluster.

This problem has been noted in many galaxy clusters but RX J1532 is an extreme case, where the cooling of gas should be especially dramatic because of the high density of gas near the center. Out of the thousands of clusters known to date, less than a dozen are as extreme as RX J1532. The Phoenix Cluster is the most extreme, where, conversely, large numbers of stars have been observed to be forming.

What is stopping large numbers of stars from forming in RX J1532? Images from the Chandra X-ray Observatory and the NSF's Karl G. Jansky Very Large Array (VLA) have provided an answer to this question. The X-ray image shows two large cavities in the hot gas on either side of the central galaxy. The Chandra image has been specially processed to emphasize the cavities. Both cavities are aligned with jets seen in radio images from the VLA. The location of the supermassive black hole between the cavities is strong evidence that the supersonic jets generated by the black hole have drilled into the hot gas and pushed it aside, forming the cavities.

Shock fronts - akin to sonic booms - caused by the expanding cavities and the release of energy by sound waves reverberating through the hot gas provide a source of heat that prevents most of the gas from cooling and forming new stars.

The cavities are each about 100,000 light years across, roughly equal to the width of the Milky Way galaxy. The power needed to generate them is among the largest known in galaxy clusters. For example, the power is almost 10 times greater than required to create the well-known cavities in Perseus.

Artist's view of the Chandra X-ray Observatory

Although the energy to power the jets must have been generated by matter falling toward the black hole, no X-ray emission has been detected from infalling material. This result can be explained if the black hole is "ultramassive" rather than supermassive, with a mass more than 10 billion times that of the sun. Such a black hole should be able to produce powerful jets without consuming large amounts of mass, resulting in very little radiation from material falling inwards.

Another possible explanation is that the black hole has a mass only about a billion times that of the sun but is spinning extremely rapidly. Such a black hole can produce more powerful jets than a slowly spinning black hole when consuming the same amount of matter. In both explanations the black hole is extremely massive.

A more distant cavity is also seen at a different angle with respect to the jets, along a north-south direction. This cavity is likely to have been produced by a jet from a much older outburst from the black hole. This raises the question of why this cavity is no longer aligned with the jets. There are two possible explanations. Either large-scale motion of the gas in the cluster has pushed it to the side or the black hole is precessing, that is, wobbling like a spinning top.

A paper describing this work was published in the November 10th, 2013 issue of The Astrophysical Journal and is available online (http://arxiv.org/abs/1306.0907). The first author is Julie Hlavacek-Larrondo from Stanford University. The Hubble data used in this analysis were from the Cluster Lensing and Supernova survey, led by Marc Postman from Space Telescope Science Institute: http://www.stsci.edu/~postman/CLASH/Home.html

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Mass., controls Chandra's science and flight operations.

For more information about Chandra X-ray Observatory, visit: http://www.nasa.gov/mission_pages/chandra/main/

Chandra on Flickr: http://www.flickr.com/photos/nasamarshall/sets/72157606205297786/

Images, Text, Credits: X-ray: NASA/CXC/Stanford/J.Hlavacek-Larrondo et al, Optical: NASA/ESA/STScI/M.Postman & CLASH team.

Greetings, Orbiter.ch

mercredi 22 janvier 2014

Herschel discovers water vapour around dwarf planet Ceres










ESA / NASA - Herschel Exploring the Clod Universe patch.

22 January 2014

Artist’s impression of Ceres

ESA’s Herschel space observatory has discovered water vapour around Ceres, the first unambiguous detection of water vapour around an object in the asteroid belt.

With a diameter of 950 km, Ceres is the largest object in the asteroid belt, which lies between the orbits of Mars and Jupiter. But unlike most asteroids, Ceres is almost spherical and belongs to the category of ‘dwarf planets’, which also includes Pluto.

It is thought that Ceres is layered, perhaps with a rocky core and an icy outer mantle. This is important, because the water-ice content of the asteroid belt has significant implications for our understanding of the evolution of the Solar System.

When the Solar System formed 4.6 billion years ago, it was too hot in its central regions for water to have condensed at the locations of the innermost planets, Mercury, Venus, Earth and Mars. Instead, it is thought that water was delivered to these planets later during a prolonged period of intense asteroid and comet impacts around 3.9 billion years ago.

Water detection on Ceres

While comets are well known to contain water ice, what about asteroids? Water in the asteroid belt has been hinted at through the observation of comet-like activity around some asteroids – the so-called Main Belt Comet family – but no definitive detection of water vapour has ever been made.

Now, using the HIFI instrument on Herschel to study Ceres, scientists have collected data that point to water vapour being emitted from the icy world’s surface.

“This is the first time that water has been detected in the asteroid belt, and provides proof that Ceres has an icy surface and an atmosphere,” says Michael Küppers of ESA’s European Space Astronomy Centre in Spain, lead author of the paper published in Nature.

Although Herschel was not able to make a resolved image of Ceres, the astronomers were able to derive the distribution of water sources on the surface by observing variations in the water signal during the dwarf planet’s 9-hour rotation period. Almost all of the water vapour was seen to be coming from just two spots on the surface.

Artist’s impression of Ceres with water detection details for 11 October 2012

“We estimate that approximately 6 kg of water vapour is being produced per second, requiring only a tiny fraction of Ceres to be covered by water ice, which links nicely to the two localised surface features we have observed,” says Laurence O’Rourke, Principal Investigator for the Herschel asteroid and comet observation programme called MACH-11, and second author on the Nature paper.

The most straightforward explanation of the water vapour production is through sublimation, whereby ice is warmed and transforms directly into gas, dragging the surface dust with it, and thus exposing fresh ice underneath to sustain the process. Comets work in this fashion.

The two emitting regions are about 5% darker than the average on Ceres. Able to absorb more sunlight, they are then likely the warmest regions, resulting in a more efficient sublimation of small reservoirs of water ice.

An alternative possibility is that geysers or icy volcanoes – cryovolcanism – play a role in the dwarf planet’s activity.

Much more detailed information on Ceres is expected soon, as NASA’s Dawn mission is currently en route there for an arrival in early 2015. It will provide close-up mapping of the surface and monitor how the water activity is generated and varies with time.

“Herschel’s discovery of water vapour outgassing from Ceres gives us new information on how water is distributed in the Solar System. Since Ceres constitutes about one fifth of the total mass of asteroid belt, this finding is important not only for the study of small Solar System bodies in general, but also for learning more about the origin of water on Earth,” says Göran Pilbratt, ESA’s Herschel Project Scientist.

More information:

“Localised sources of water vapour on dwarf planet (1) Ceres,” by M. Küppers et al. is published in Nature 23 January 2014.

Ceres was observed on four occasions between November 2011 and March 2013 initially as part of the MACH-11 (Measurements of 11 Asteroids and Comets with Herschel) Guaranteed Time Programme, and complemented by two additional Director’s Discretionary Time observations that confirmed the tentative detection and measured the variation in water vapour as a function of rotation period.

Related links:

Herschel overview: http://www.esa.int/Our_Activities/Space_Science/Herschel_overview

Online Showcase of Herschel Images OSHI: http://oshi.esa.int/

Herschel in depth: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=16

Herschel Science Centre: http://herschel.esac.esa.int/

NASA’s Dawn mission: http://dawn.jpl.nasa.gov/

Images, Text, Credits: ESA / ATG medialab / Küppers et al.

Best regards, Orbiter.ch

Sneak Preview of Survey Telescope Treasure Trove












ESO - European Southern Observatory logo.

22 January 2014

VST images the Lagoon Nebula

The VLT Survey Telescope (VST) at ESO's Paranal Observatory in Chile has captured this richly detailed new image of the Lagoon Nebula. This giant cloud of gas and dust is creating intensely bright young stars, and is home to young stellar clusters. This image is a tiny part of just one of eleven public surveys of the sky now in progress using ESO telescopes. Together these are providing a vast legacy of publicly available data for the global astronomical community.

The star formation region Messier 8 in the constellation of Sagittarius

The Lagoon Nebula is an intriguing object located around 5000 light-years from us in the constellation of Sagittarius (The Archer). Also known as Messier 8, it is a giant cloud 100 light-years across, where new stars are forming within its plumes of gas and dust [1]. This new 16 000-pixel-wide image is from the VLT Survey Telescope (VST), one of two dedicated survey telescopes at ESO's Paranal Observatory in northern Chile. A zoomable version of the image allows the viewers to explore the many nooks and crannies of this fascinating object.

Wide-field view of the Lagoon Nebula

The VST was not pointed at the Lagoon deliberately, it simply was included as part of a huge imaging survey called VPHAS+ that covered a much larger region of the Milky Way. VPHAS+ is just one of three imaging surveys using visible light with the VST. These are complemented by six infrared surveys with the VISTA survey telescope.

Excerpts from a VST image of the Lagoon Nebula

The surveys are addressing many important questions in modern astronomy. These include the nature of dark energy, searching for brilliant quasars in the early Universe, probing the structure of the Milky Way and looking for unusual and hidden objects, studying the neighbouring Magellanic Clouds in great detail, and many other topics. History shows that surveys often find things that are unexpected and these surprises are crucial for the progress of astronomical research.

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Zooming in on a new image of the Lagoon Nebula from the VST

As well as the nine imaging surveys with VISTA and the VST there are also two additional surveys that are in progress using other ESO telescopes. One, the Gaia-ESO Survey, is using the Very Large Telescope at Paranal to map the properties of more than 100 000 stars in the Milky Way, and another (PESSTO) is following up on transient objects such as supernovae using the New Technology Telescope at La Silla [2].

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Panning across a new image of the Lagoon Nebula from the VST

Some of these surveys began back in 2010, and some much more recently, but data from all of them are now being made public and are accessible to astronomers around the world through ESO's archive [3].

Although they are still in progress, the surveys are already allowing astronomers to make many discoveries. Just a few of these new results include new star clusters found in the VVV survey (eso1128, eso1141), the best map yet of the central parts of our Milky Way (eso1242, eso1339), a very deep view of the infrared sky (eso1213) and, very recently, some of the most distant quasars discovered so far (from the VISTA VIKING survey).

The ESO Public Surveys will continue for many years, and their astronomical legacy value will stretch many decades into the future.

Notes:

[1] ESO has produced several stunning views of this object before — most notably a huge 370-megapixel image as part of the GigaGalaxy Zoom project (eso0936) — and has also provided a completely different view from the VISTA (the Visible and Infrared Survey Telescope for Astronomy) VVV survey, which explored the Lagoon's mysteries in the infrared (eso1101).

[2] More information about all eleven surveys are available here and a comprehensive description of their current status and results is given in a dedicated section of the latest ESO Messenger.

[3] An overview of the data releases from the eleven ESO public survey projects is also available.

More information:

ESO is the foremost intergovernmental astronomy organisation in Europe and the world's most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world's largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world's biggest eye on the sky”.

Links:

Photos of VST: http://www.eso.org/public/images/archive/search/?adv=&subject_name=VLT%20Survey%20Telescope

Photos of VISTA: http://www.eso.org/public/images/archive/search/?adv=&subject_name=Visible%20and%20Infrared%20Survey%20Telescope%20for%20Astronomy

Images, Text, Credits: ESO/VPHAS+ team/IAU and Sky & Telescope/ESO/Digitized Sky Survey 2/Acknowledgement: Davide De Martin. Videos: ESO/VPHAS+ team/Digitized Sky Survey 2/Nick Risinger (skysurvey.org). Music: movetwo.

Greetings, Orbiter.ch

mardi 21 janvier 2014

Rock That Appeared in Front of Opportunity on "Murray Ridge"












NASA - Mars Science Laboratory (MSL) patch.

Jan. 21, 2014


This before-and-after pair of images of the same patch of ground in front of NASA's Mars Exploration Rover Opportunity 13 days apart documents the arrival of a bright rock onto the scene. The rover had completed a short drive just before taking the second image, and one of its wheels likely knocked the rock -- dubbed "Pinnacle Island" -- to this position. The rock is about the size of a doughnut.

The images are from Opportunity's panoramic camera (Pancam). The one on the left is from 3,528th Martian day, or sol, of the rover's work on Mars (Dec. 26, 2013). The one on the right, with the newly arrived rock, is from Sol 3540 (Jan. 8, 2014). Much of the rock is bright-toned, nearly white. A portion is deep red in color. Pinnacle Island may have been flipped upside down when a wheel dislodged it, providing an unusual circumstance for examining the underside of a Martian rock.

Artist's view of the Opportunity Rover

The site is on "Murray Ridge," a section of the rim of Endeavour Crater where Opportunity is working on north-facing slopes during the rover's sixth Martian winter.

For more information about Opportunity, visit  http://www.nasa.gov/rovers and http://marsrovers.jpl.nasa.gov

Images, Text, Credits: NASA / JPL-Caltech / Cornell Univ. / Arizona State Univ.

Best regards, Orbiter.ch

Alphasat’s pioneering high-frequency hosted payload set for experiments








ESA - AlphaSat Mission logo.

21 January 2014

Alphasat's TDP 5 measures the impact of cloud coverage on its signal

European scientists can now begin probing unexplored frequencies, as mega telecom satellite Alphasat’s ‘Aldo Paraboni Q/V Band’ hosted payload has been given the green light to begin experiments.

Six months after launch, the payload has undergone many commissioning and in-orbit tests before receiving the go-ahead to start operations. The Q/V-band mission, named after the late Italian scientist Aldo Paraboni who inspired it, is one of four technology demonstration payloads carried by Alphasat. It is dedicated to exploring the higher-frequency Q- and V-bands at 38 and 48 GHz.

Alphasat's hosted payloads before launch

It is necessary to look into using the higher frequencies for carrying data because our current information highways – the Ku- and Ka-bands from 12 to 18 GHz and 26.5 to 40 GHz, respectively – are becoming increasingly congested. Expanding the range of frequencies we can use means more bandwidth availability.

With all tests now complete confirming the payload is healthy and performing well, the scientists can start conducting their experiments. They will be analysing the data from the two independent packages that make up the Aldo Paraboni payload.

Firstly, the communication experiment receives and relays broadband data between stations in the Q/V-bands and allows their performance to be tested. This is important, because one of the challenges that these frequencies have presented in the past is their susceptibility to atmospheric conditions. Turbulent weather conditions can cause strong signal fading.

Alphasat's TDP 5 Comex experiment in orbit

The complementary propagation payload transmits two beacon signals across Europe, allowing scientists to collect the two sets of data, compare their performance and determine how they are affected by weather.

Scientists can now begin analysing the data produced by the payload, and model future broadband communications from geostationary satellites on their discoveries.

The Aldo Paraboni payload is the first to carry communications at such high frequency bands on a commercial geostationary satellite over Europe. Developed by Italian companies Thales Alenia Space and Space Engineering and supported by Italy’s ASI space agency, the Aldo Paraboni mission paves the way for future telecom satellites operating at Q/V frequencies. This will result in more available bandwidth and the possibility of smaller user terminals, as more research will eradicate the need for oversized links to compensate for fading.

Close up of TDP 5's propagation experiment

“The Aldo Paraboni payload is the Q/V Band programme’s space segment,” said Enrico Russo, ASI Head of Telecommunications and Integrated Applications Unit, “and it is in line with the long-standing ASI goal to pioneer the use of the higher frequency bands for satellite telecommunications.”

The payload is carried on Inmarsat’s Alphasat, the largest European telecom satellite ever built at 6.6 tonnes when launched on 25 July 2013. The satellite is now in its final orbital position at 25°E, having completed testing.

Alphasat and its hosted payloads are also the result of one of ESA’s biggest public–private partnerships to date, involving ESA, Inmarsat and around a dozen institutional and industrial partners from all over Europe.

Stephane Lascar, Head of Telecommunications Satellite Programmes of ESA, added: “The Aldo Paraboni payload is an important and sophisticated piece of technology hosted on Alphasat that will pave the way to future telecom applications. We are pleased to start its operations.

“Alphasat also embodies the next step in satcom as a true feat of engineering and partnership; we are looking forward to the unique results of this payload’s experiments.”

More information:

Bulletin 148: Alphasat TDPs: http://www.esa.int/About_Us/ESA_Publications/ESA_Publications_Bulletin/ESA_i_Bulletin_i_148_November_2011

TDP 5 factsheet: http://esamultimedia.esa.int/docs/technology/TDP5_factsheet.pdf

Partners:

Thales Alenia Space: http://www.thalesgroup.com/space/

Space Engineering: http://www.space.it/

ASI: http://www.asi.it/en

Images, Text, Credits: ESA / Astrium.

Greetings, Orbiter.ch

Infrared Image of Saturn's Rings












NASA  - Cassini Mission to Saturn patch.

Jan. 21, 2014

Infrared Image of Saturn's Rings

Although it may look to our eyes like other images of the rings, this infrared image of Saturn's rings was taken with a special filter that will only admit light polarized in one direction. Scientists can use these images to learn more about the nature of the particles that make up Saturn's rings.

The bright spot in the rings is the "opposition surge" where the Sun-Ring-Spacecraft angle passes through zero degrees. Ring scientists can also use the size and magnitude of this bright spot to learn more about the surface properties of the ring particles.

This view looks toward the sunlit side of the rings from about 19 degrees above the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on Aug. 18, 2013 using a spectral filter sensitive to wavelengths of near-infrared light centered at 705 nanometers.

Cassini spacecraft

The view was acquired at a distance of approximately 712,000 miles (1.1 million kilometers) from Saturn and at a Sun-rings-spacecraft, or phase, angle of 7 degrees. Image scale is 43 miles (68 kilometers) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory manages the mission for NASA's Science Mission Directorate, Washington, D.C. JPL is a division of Caltech. For more information on Cassini, visit http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov and http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Images, Text, Credits: NASA / JPL-Caltech / Space Science Institute.

Cheers, Orbiter.ch

CryoSat detects hidden Antarctic pattern







ESA - CryoSat Mission logo.

21 January 2014

Near the centre of Antarctica, measurements from CryoSat show an unusual pattern in the ice sheet’s elevation. Scientists have now found the reason for this pattern – and the discovery is leading to even more accurate measurements from ESA’s ice mission.

CryoSat carries a radar altimeter that can ‘see’ through clouds and in the dark, providing continuous measurements over areas like central Antarctica that are prone to bad weather and long periods of darkness.

Antarctic artefacts

The radar measures the surface height variation of ice by timing the interval between the transmission and reception of very short radar pulses as the satellite orbits Earth.

CryoSat collects data over Antarctica while passing on northbound and southbound orbits. But the data show an unusual pattern of height differences where these orbit cross, radiating from the South Pole. 

“When this static pattern in the CryoSat measurements emerged, alarm bells started to ring,” said Tom Armitage from University College London, who led the study.

Artefact: close-up

“At first, we thought that there could be an issue with the satellite itself, such as a miscalculation of the altitude, a timing error or a problem with one of the corrections we apply to the measurements.”

After eliminating the possibility of these errors through careful experimentation, scientists discovered that the pattern was caused by the way the satellite signal is scattered from the ice sheet surface.

Antarctica has some of the strongest and most persistent winds on Earth, which leave permanent erosional and depositional features on the surface and in the snow pack. The scientists found that that these wind-driven features modify CryoSat’s radar measurements in such a way as to produce the pattern that has been detected.

“The pattern is not an ‘error’, but an artefact arising from the interaction of the polarisation of CryoSat’s antenna with the structure of the ice surface induced by wind,” said Tommaso Parrinello, CryoSat Mission Manager.

CryoSat

It has long been known that wind-driven directional properties of the ice sheet surface can affect the signal received by radar altimeters, but has never been seen so clearly. The most striking feature of the pattern – the diamond ring pattern close to the pole – had not been seen by past altimeter missions because they did not fly far enough south.

Since the pattern appears to be stable over time, the data can easily be corrected, ensuring that CryoSat’s past and future measurements of Antarctica are precise. The discovery also helps scientists better understand the interaction between radar waves and ice sheet surfaces.

For more information about CryoSat Mission, visit: http://www.esa.int/Our_Activities/Observing_the_Earth/CryoSat

Images, Text, Credits: ESA / MSSL / UCL / IEEE.

Greetings, Orbiter.ch

lundi 20 janvier 2014

Fifty years of quarks












CERN - European Organization for Nuclear Research logo.

Jan. 20, 2014

In 1964, two physicists independently proposed the existence of the subatomic particles known as quarks.

Physicists Murray Gell-Mann and George Zweig were working independently on a theory for strong interaction symmetry in particle physics. Within this framework, they proposed that important properties of the strongly interacting particles – hadrons – could be explained if they were made up of constituent particles.


Image above: Murray Gell-Mann visited CERN and the ATLAS experiment in January last year (Image: Maximilien Brice/CERN).

In 1961 Gell-Mann had introduced a symmetry scheme he called the Eightfold Way, which was based on the mathematical symmetry known as SU(3). The scheme (for which he received the Nobel prize in physics in 1969) classified the hadrons into two main groups, rather as the Periodic Table classifies the chemical elements.

Gell-Mann built upon this work in a new model that could successfully describe – among other things – the magnetic properties of protons and neutrons. But Gell-Mann's model required the existence of three new elementary particles, which he called "quarks."

Gell-Mann says that he first came up with the sound "quork", and later chanced upon the phrase "Three quarks for Muster Mark" in James Joyce's Finnegans Wake. As Joyce presumably intended the word to rhyme with "Mark", people have been divided on the pronunciation ever since.

Physicist George Zweig made his contribution to the field while he was a visitor to CERN in a paper dated 17 January 1964, in which he proposed: "Both mesons and baryons are constructed from a set of three fundamental particles called aces." Though Zweig's name for the particles did not stick, he showed that some properties of hadrons could be explained by treating them as triplets of other constituent particles.


Image above: George Zweig visited CERN and the ALICE cavern in September last year (Image: Panagiotis Charitos).

Both Gell-Mann’s quarks and Zweig’s aces had to have electrical charges equal to 1/3 or 2/3 that of an electron or proton, suggesting that an experimental search for these constituents would reveal whether or not they existed.

In 1968, a series of electron-proton scattering experiments by the MIT-SLAC collaboration at the Stanford Linear Accelerator Center (SLAC) in the US revealed the first signs that nucleons have an inner structure. The team fired electrons at protons and observed how the electrons bounced off. The scattering patterns were identified as being caused by point-like particles inside the protons. In the subsequent years, by combining these results with others from neutrino-scattering in the Gargamelle bubble chamber at CERN, it became clear that these constituents really do have charges of 1/3 and 2/3.

Quarks are now a key part of the Standard Model. In numerous experiments at CERN including those at the Large Hadron Collider (LHC), physicists are measuring the properties of Gell-Mann and Zweig's particles with ever-greater precision.

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 20 Member States.

More on quarks:

Watch George Zweig's technical account the history of quarks (Recorded at CERN in September 2013): http://cds.cern.ch/record/1602433

Related links:

Large Hadron Collider (LHC): http://home.web.cern.ch/about/accelerators/large-hadron-collider

ATLAS experiment: http://home.web.cern.ch/about/experiments/atlas

Stanford Linear Accelerator Center (SLAC): https://www6.slac.stanford.edu/about/slac-history.aspx

Image (mentioned), Text, Credits: CERN / Cian O'Luanaigh.

Cheers, Orbiter.ch

ESA’s ‘sleeping beauty’ wakes up from deep space hibernation












ESA - Rosetta Mission patch.

20 January 2014

It was a fairy-tale ending to a tense chapter in the story of the Rosetta space mission this evening as ESA heard from its distant spacecraft for the first time in 31 months.

Rosetta is chasing down Comet 67P/Churyumov-Gerasimenko, where it will become the first space mission to rendezvous with a comet, the first to attempt a landing on a comet’s surface, and the first to follow a comet as it swings around the Sun.

Since its launch in 2004, Rosetta has made three flybys of Earth and one of Mars to help it on course to its rendezvous with 67P/Churyumov-Gerasimenko, encountering asteroids Steins and Lutetia along the way.

Rosetta Wake-up signal

Operating on solar energy alone, Rosetta was placed into a deep space slumber in June 2011 as it cruised out to a distance of nearly 800 million km from the warmth of the Sun, beyond the orbit of Jupiter.

Now, as Rosetta’s orbit has brought it back to within ‘only’ 673 million km from the Sun, there is enough solar energy to power the spacecraft fully again.

Thus today, still about 9 million km from the comet, Rosetta’s pre-programmed internal ‘alarm clock’ woke up the spacecraft. After warming up its key navigation instruments, coming out of a stabilising spin, and aiming its main radio antenna at Earth, Rosetta sent a signal to let mission operators know it had survived the most distant part of its journey.

Rosetta calls home

The signal was received by both NASA’s Goldstone and Canberra ground stations and at 18:18 GMT/ 19:18 CET, during the first window of opportunity the spacecraft had to communicate with Earth. It was immediately confirmed in ESA’s space operations centre in Darmstadt and the successful wake-up announced via the @ESA_Rosetta twitter account, which tweeted: “Hello, World!”

“We have our comet-chaser back,” says Alvaro Giménez, ESA’s Director of Science and Robotic Exploration. “With Rosetta, we will take comet exploration to a new level. This incredible mission continues our history of ‘firsts’ at comets, building on the technological and scientific achievements of our first deep space mission Giotto, which returned the first close-up images of a comet nucleus as it flew past Halley in 1986.” 

“This was one alarm clock not to hit snooze on, and after a tense day we are absolutely delighted to have our spacecraft awake and back online,” adds Fred Jansen, ESA’s Rosetta mission manager.

video
How Rosetta wakes up from deep space hibernation

Comets are considered the primitive building blocks of the Solar System and likely helped to ‘seed’ Earth with water, perhaps even the ingredients for life. But many fundamental questions about these enigmatic objects remain, and through its comprehensive, in situ study of Comet 67P/Churyumov-Gerasimenko, Rosetta aims to unlock the secrets contained within.

“All other comet missions have been flybys, capturing fleeting moments in the life of these icy treasure chests,” says Matt Taylor, ESA’s Rosetta project scientist. “With Rosetta, we will track the evolution of a comet on a daily basis and for over a year, giving us a unique insight into a comet’s behaviour and ultimately helping us to decipher their role in the formation of the Solar System.”

But first, essential health checks on the spacecraft must be completed. Then the eleven instruments on the orbiter and ten on the lander will be turned on and prepared for studying Comet 67P/Churyumov-Gerasimenko.

“We have a busy few months ahead preparing the spacecraft and its instruments for the operational challenges demanded by a lengthy, close-up study of a comet that, until we get there, we know very little about,” says Andrea Accomazzo, ESA’s Rosetta operations manager.

Rosetta and Philae at comet

Rosetta’s first images of 67P/Churyumov-Gerasimenko are expected in May, when the spacecraft is still 2 million km from its target. Towards the end of May, the spacecraft will execute a major manoeuvre to line up for its critical rendezvous with the comet in August.

After rendezvous, Rosetta will start with two months of extensive mapping of the comet’s surface, and will also make important measurements of the comet’s gravity, mass and shape, and assess its gaseous, dust-laden atmosphere, or coma. The orbiter will also probe the plasma environment and analyse how it interacts with the Sun’s outer atmosphere, the solar wind.

Using these data, scientists will choose a landing site for the mission’s 100 kg Philae probe. The landing is currently scheduled for 11 November and will be the first time that a landing on a comet has ever been attempted.

In fact, given the almost negligible gravity of the comet’s 4 km-wide nucleus, Philae will have to use ice screws and harpoons to stop it from rebounding back into space after touchdown.

 Rosetta Wake Up! Rosetta arrives at Comet 67P

 Video above: This video was made ​​with Orbiter Space Flight Simulator 2010, reproduced in accelerated half of the film, the arrival of Rosetta comet 67P Churyumov-Gerasimenko, its orbit and dropping the Philae probe that landed on the comet and deploys its instruments. This video participate to the contest "Wake Up Rosetta."

Among its wide range of scientific measurements, Philae will send back a panorama of its surroundings, as well as very high-resolution pictures of the surface. It will also perform an on-the-spot analysis of the composition of the ices and organic material, including drilling down to 23 cm below the surface and feeding samples to Philae’s on-board laboratory for analysis.

The focus of the mission will then move to the ‘escort’ phase, during which Rosetta will stay alongside the comet as it moves closer to the Sun, monitoring the ever-changing conditions on the surface as the comet warms up and its ices sublimate.

The comet will reach its closest distance to the Sun on 13 August 2015 at about 185 million km, roughly between the orbits of Earth and Mars. Rosetta will follow the comet throughout the remainder of 2015, as it heads away from the Sun and activity begins to subside.

“We will face many challenges this year as we explore the unknown territory of comet 67P/Churyumov-Gerasimenko and I’m sure there will be plenty of surprises, but today we are just extremely happy to be back on speaking terms with our spacecraft,” adds Matt Taylor.

For more information about Rosetta Mission, visit:http://www.esa.int/Our_Activities/Space_Science/Rosetta

Images, Text, Credits: ESA / C.Carreau / J. Huart / Videos: ESA / ATG medialab; music: B. Lynne. / Orbiter.ch Aerospace Studio. Musics: Greg Baumont / Blue Star - Wood / Czech Symphony Orchestra / Dead Zone - Movie theme.

Greetings, Orbiter.ch