vendredi 25 mars 2011

NASA Stardust Spacecraft Officially Ends Operations

NASA - Stardust-NexT Mission patch.

March 25, 2011

NASA's Stardust spacecraft sent its last transmission to Earth at 7:33 p.m. EDT Thursday, March 24, shortly after depleting fuel and ceasing operations. During an 11-year period, the venerable spacecraft collected and returned comet material to Earth and was reused after the end of its prime mission in 2006 to observe and study another comet during February 2011.

The Stardust team performed the burn to depletion, because the comet hunter was literally running on fumes. The depletion maneuver command was sent from the Stardust-NExT mission control area at Lockheed Martin Space Systems in Denver. The operation was designed to fire Stardust's rockets until no fuel remained in the tank or fuel lines. The spacecraft sent acknowledgment of its last command from approximately 194 million miles away in space.

"This is the end of the spacecraft's operations, but really just the beginnings of what this spacecraft's accomplishments will give to planetary science," said Lindley Johnson, Stardust-NExT and Discovery program executive at NASA Headquarters in Washington. "The treasure-trove of science data and engineering information collected and returned by Stardust is invaluable for planning future deep space planetary missions."

After completion of the burn, mission personnel began comparing the computed amount of fuel consumed during the engine firing with the anticipated amount based on consumption models. The models are required to track fuel levels, because there are no fully reliable fuel gauges for spacecraft in the weightless environment of space. Mission planners use approximate fuel usage by reviewing the history of the vehicle's flight, how many times and how long its rocket motors fired.

"Stardust's motors burned for 146 seconds," said Allan Cheuvront, Lockheed Martin Space Systems Company program manager for Stardust-NExT in Denver. "We'll crunch the numbers and see how close the reality matches up with our projections. That will be a great data set to have in our back pocket when we plan for future missions."

Stardust spacecraft

Launched Feb. 7, 1999, Stardust flew past the asteroid named Annefrank and traveled halfway to Jupiter to collect the particle samples from the comet Wild 2. The spacecraft returned to Earth's vicinity to drop off a sample return capsule eagerly awaited by comet scientists.

NASA re-tasked the spacecraft as Stardust-NExT to perform a bonus mission and fly past comet Tempel 1, which was struck by the Deep Impact mission in 2005. The mission collected images and other scientific data to compare with images of that comet collected by the Deep Impact mission in 2005. Stardust traveled approximately 13 million miles around the sun in the weeks after the successful Tempel 1 flyby. The Stardust-NExT mission met all mission goals, and the spacecraft was extremely successful during both missions. From launch until final rocket engine burn, Stardust travelled approximately 3.54 billion miles.

After the mileage logged in space, the Stardust team knew the end was near for the spacecraft. With its fuel tank empty and final radio transmission concluded, history's most traveled comet hunter will move from NASA's active mission roster to retired.

"This kind of feels like the end of one of those old western movies where you watch the hero ride his horse towards the distant setting sun -- and then the credits begin to roll," said Stardust-NExT project manager Tim Larson from NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Only there's no setting sun in space."

Stardust and Stardust-NExT missions were managed by JPL for NASA's Science Mission Directorate in Washington. The missions were part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Joe Veverka of Cornell University was the Stardust-NExT principal investigator. Don Brownlee of the University of Washington in Seattle was the Stardust principal investigator. Lockheed Martin Space Systems built the spacecraft and managed day-to-day mission operations.

For more information about Stardust and Stardust-NExT, visit:

Images, Text, Credit: NASA.


Tycho Supernova Remnant

NASA - Chandra X-Ray Observatory logo.


This image comes from a very deep Chandra observation of the Tycho supernova remnant, produced by the explosion of a white dwarf star in our Galaxy. Low-energy X-rays (red) in the image show expanding debris from the supernova explosion and high energy X-rays (blue) show the blast wave, a shell of extremely energetic electrons . These high-energy X-rays show a pattern of X-ray "stripes" never previously seen in a supernova remnant. Some of the brightest stripes can also directly be seen in the full color image, on the right side of the remnant pointing from the outer rim to the interior. The stellar background is from the Digitized Sky Survey and only shows stars outside the remnant.

These stripes may provide the first direct evidence that supernova remnants can accelerate particles to energies a hundred times higher than achieved by the most powerful particle accelerator on Earth, the Large Hadron Collider. The results could explain how some of the extremely energetic particles bombarding the Earth, called cosmic rays, are produced, and they provide support for a theory about how magnetic fields can be dramatically amplified in such blast waves.

The X-ray stripes are thought to be regions where the turbulence is greater and the magnetic fields more tangled than surrounding areas. Electrons become trapped in these regions and emit X-rays as they spiral around the magnetic field lines. Regions with enhanced turbulence and magnetic fields were expected in supernova remnants, but the motion of the most energetic particles -- mostly protons -- was predicted to leave a messy network of holes and dense walls corresponding to weak and strong regions of magnetic fields, respectively. Therefore, the detection of stripes was a surprise.

The size of the holes was expected to correspond to the radius of the spiraling motion of the highest energy protons in the supernova remnant. These energies equal the highest energies of cosmic rays thought to be produced in our Galaxy. The spacing between the stripes corresponds to this size, providing evidence for the existence of these extremely energetic protons.

The Tycho supernova remnant is named for the famous Danish astronomer Tycho Brahe, who reported observing the supernova in 1572. It is located in the Milky Way, about 13,000 light years from Earth. Because of its proximity and intrinsic brightness, the supernova was so bright that it could be seen during the daytime with the naked eye.

Read more/access larger images:

Images, Text, Credits: X-ray: NASA / CXC / Rutgers / K.Eriksen et al.; Optical: DSS.


jeudi 24 mars 2011

Suzaku Shows Clearest Picture Yet Of Perseus Galaxy Cluster

JAXA - NASA Suzaku / Astro-2e X-ray Telescopes logo.

March 24, 2011

X-ray observations made by the Suzaku observatory provide the clearest picture to date of the size, mass and chemical content of a nearby cluster of galaxies. The study also provides the first direct evidence that million-degree gas clouds are tightly gathered in the cluster's outskirts.

Suzaku is sponsored by the Japan Aerospace Exploration Agency (JAXA) with contributions from NASA and participation by the international scientific community. The findings will appear in the March 25 issue of the journal Science.

Galaxy clusters are millions of light-years across, and most of their normal matter comes in the form of hot X-ray-emitting gas that fills the space between the galaxies.

Artist's conception of Suzaku in orbit. Image credit: ISAS / JAXA

"Understanding the content of normal matter in galaxy clusters is a key element for using these objects to study the evolution of the universe," explained Adam Mantz, a co-author of the paper at NASA's Goddard Space Flight Center in Greenbelt, Md.

Clusters provide independent checks on cosmological values established by other means, such as galaxy surveys, exploding stars and the cosmic microwave background, which is the remnant glow of the Big Bang. The cluster data and the other values didn't agree.

NASA's Wilkinson Microwave Anisotropy Probe (WMAP) explored the cosmic microwave background and established that baryons -- what physicists call normal matter -- make up only about 4.6 percent of the universe. Yet previous studies showed that galaxy clusters seemed to hold even fewer baryons than this amount.

Suzaku images of faint gas at the fringes of a nearby galaxy cluster have allowed astronomers to resolve this discrepancy for the first time. The satellite's ideal target for this study was the Perseus Galaxy Cluster, which is located about 250 million light-years away and named for the constellation in which it resides. It is the brightest extended X-ray source beyond our own galaxy, and also the brightest and closest cluster in which Suzaku has attempted to map outlying gas.

"Before Suzaku, our knowledge of the properties of this gas was limited to the innermost parts of clusters, where the X-ray emission is brightest, but this left a huge volume essentially unexplored," said Aurora Simionescu, the study's lead researcher at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University.

Perseus Galaxy Cluster

In late 2009, Suzaku's X-ray telescopes repeatedly observed the cluster by progressively imaging areas farther east and northwest of the center. Each set of images probed sky regions two degrees across -- equivalent to four times the apparent width of the full moon or about 9 million light-years at the cluster's distance. Staring at the cluster for about three days, the satellite mapped X-rays with energies hundreds of times greater than that of visible light.

From the data, researchers measured the density and temperature of the faint X-ray gas, which let them infer many other important quantities. One is the so-called virial radius, which essentially marks the edge of the cluster. Based on this measurement, the cluster is 11.6 million light-years across and contains more than 660 trillion times the mass of the sun. That's nearly a thousand times the mass of our Milky Way galaxy.

The researchers also determined the ratio of the cluster's gas mass to its total mass, including dark matter -- the mysterious substance that makes up about 23 percent of the universe, according to WMAP. By virtue of their enormous size, galaxy clusters should contain a representative sample of cosmic matter, with normal-to-dark-matter ratios similar to WMAP's. Yet the outer parts of the Perseus cluster seemed to contain too many baryons, the opposite of earlier studies, but still in conflict with WMAP.

To solve the problem, researchers had to understand the distribution of hot gas in the cluster, the researchers say. In the central regions, the gas is repeatedly whipped up and smoothed out by passing galaxies. But computer simulations show that fresh infalling gas at the cluster edge tends to form irregular clumps.

Not accounting for the clumping overestimates the density of the gas. This is what led to the apparent disagreement with the fraction of normal matter found in the cosmic microwave background.

"The distribution of these clumps and the fact that they are not immediately destroyed as they enter the cluster are important clues in understanding the physical processes that take place in these previously unexplored regions," said Steve Allen at KIPAC, the principal investigator of the Suzaku observations.

Goddard supplied Suzaku's X-ray telescopes and data-processing software, and it continues to operate a facility that supports U.S. astronomers who use the spacecraft.

Suzaku (Japanese for "red bird of the south") is the fifth Japanese X-ray astronomy satellite. It was launched as Astro-E2 on July 10, 2005, and renamed in orbit. The observatory was developed at JAXA's Institute of Space and Astronautical Science in collaboration with NASA and other Japanese and U.S. institutions.

For more information and images about this finding, visit:

Images, Text, Credts: NASA / JAXA / ISAS / Goddard.


Integral spots matter a millisecond from doom

ESA - Integral Mission patch.

24 March 2011

ESA’s Integral gamma-ray observatory has spotted extremely hot matter just a millisecond before it plunges into the oblivion of a black hole. But is it really doomed? These unique observations suggest that some of the matter may be making a great escape.

No one would want to be so close to a black hole. Just a few hundred kilometres away from its deadly surface, space is a maelstrom of particles and radiation. Vast storms of particles are falling to their doom at close to the speed of light, raising the temperature to millions of degrees.

An artist's impression of the Cygnus X-1 black hole system

Ordinarily, it takes just a millisecond for the particles to cross this final distance but hope may be at hand for a small fraction of them.

Thanks to the new Integral observations, astronomers now know that this chaotic region is threaded by magnetic fields.

This is the first time that magnetic fields have been identified so close to a black hole. Most importantly, Integral shows they are highly structured magnetic fields that are forming an escape tunnel for some of the doomed particles.

Philippe Laurent, CEA Saclay, France, and colleagues made the discovery by studying the nearby black hole, Cygnus X-1, which is ripping a companion star to pieces and feeding on its gas.

 Integral's IBIS imager sees Cygnus X-1

Their evidence points to the magnetic field being strong enough to tear away particles from the black hole’s gravitational clutches and funnel them outwards, creating jets of matter that shoot into space. The particles in these jets are being drawn into spiral trajectories as they climb the magnetic field to freedom and this is affecting a property of their gamma-ray light known as polarisation.

A gamma ray, like ordinary light, is a kind of wave and the orientation of the wave is known as its polarisation. When a fast particle spirals in a magnetic field it produces a kind of light, known as synchrotron emission, which displays a characteristic pattern of polarisation. It is this polarisation that the team have found in the gamma rays. It was a difficult observation to make.

“We had to use almost every observation Integral has ever made of Cygnus X-1 to make this detection,” says Laurent.

Integral, artist’s impression

Amassed over seven years, these repeated observations of the black hole now total over five million seconds of observing time, the equivalent of taking a single image with an exposure time of more than two months. Laurent’s team added them all together to create just such an exposure.

“We still do not know exactly how the infalling matter is turned into the jets. There is a big debate among theoreticians; these observations will help them decide,” says Laurent.

Jets around black holes have been seen before by radio telescopes but such observations cannot see the black hole in sufficient detail to know exactly how close to the black hole the jets originate. That makes these new observations invaluable.

"This discovery of polarized emission from a black hole jet is a unique result demonstrating that Integral, which is covering the high-energy band in ESA's wide spectrum of scientific missions, continues to produce key results more than eight years after its launch," says Christoph Winkler, ESA Integral Project Scientist.

Notes for editors:

Polarized Gamma-ray Emission from the Galactic Black Hole Cygnus X-1 by P. Laurent et al. is published online by Science today and will appear in a future issue of the printed journal.

Science today:

Images, Text, Credits: ESA / (Images 2) Original image by the Integral IBIS team. Image processing by ESA / ECF.


JAXA supports disaster measures following Tohoku Region Pacific Ocean Coastal Earthquake

JAXA logo labeled.

March 24, 2011 (JST)

Japan now faces unprecedented damage in a broad area not only due to the Tohoku Region Pacific Ocean Coastal Earthquake but also from the following huge tsunami tidal wave. JAXA has been actively engaging in support activities for disaster-stricken areas. We are carrying out emergency observations of the regions using the Advanced Earth Observing Satellite"DAICHI" and providing analyzed data to the government in cooperation with other international organizations.

The Wideband Internetworking Engineering Test and Demonstration Satellite "KIZUNA" (WINDS) and the Engineering Test Satellite VIII "KIKU No. 8" (ETX-VIII) are also being utilized to establish a communication environment to support disaster measures. At the International Space Station, astronauts took images of the disaster-stricken areas.

JAXA would like to express our deepest sympathy to those who are suffering from the Tohoku Region Pacific Ocean Coastal Earthquake.

Related links:

ALOS Research and Application Project:

Satellite Communications Using the KIKU No. 8 to Support Disaster Measures following the Tohoku Region Pacific Ocean Coastal Earthquake

The Japan Aerospace Exploration Agency (JAXA) began a satellite communication connection using the Engineering Test Satellite VIII "KIKU No. 8" (ETS-VIII) to support disaster measures following the Tohoku Region Pacific Ocean Costal Earthquake.

KIKU No. 8 ground antenna installed at Ofunato City Hall

On March 24, JAXA set up a ground antenna and the movable test communication terminal for the KIKU No. 8 at the Ofunato City Hall to connect the communication line of up to 768 Kbps between the City Hall and the Tsukuba Space Center via KIKU No. 8 in cooperation with the National Institution of Information and Communications Technology (NICT) based on a request from the Ministry of Education, Culture, Sports, Science and Technology, which received a petition from Ofunato City, Iwate Prefecture.

With this communication line installation, Ofunato City Hall workers began collecting information by PCs through the Internet. Apart from city hall, local fire departments and other offices can also now use the Internet and IP telephones to share information for strengthening their cooperative activities.

In addition, as one of the special features of the KIKU No. 8 is communications with a small movable test terminal, which was installed at Ofunato City, information dispatch from evacuation centers and other places through the Internet became possible, because it is easy to move around and install it. Therefore, the connection this time is expected to further contribute to a smooth recovery from the disaster.

KIKU No. 8 movable test communication terminal installed at Ofunato City Hall

A movable antenna for the Wideband Internetworking Engineering Test and Demonstration Satellite "KIZUNA" (WINDS) has already been installed at the Iwate Prefectural Office (Disaster measures headquarters) in Morioka City and in Kamaishi City (Iwate costal broad area promotion office.) In addition, another movable ground antenna for the KIZUNA was set up in Ofunato City (Iwate costal broad area promotion office) according to a request from Iwate Prefecture.

Conseptual diagram of communication system

JAXA has been carrying out technological development of satellite communications that can assist in disaster measures using the KIKU No. 8 and KIZUNA, and we would like to continue our support activities for recovery from the disaster as part of our development efforts.

Mission website:

Engineering Test Satellite VIII "KIKU No.8" (ETS-VIII):

Images, Text, Credit: Japan Aerospace Exploration Agency (JAXA).


Hylas-1 ready for service

ESA - Hylas-1 Satellite logo.

24 March 2011

It’s all systems go for Hylas-1, the first satellite created specifically to deliver broadband access to European consumers. Since its launch in November, Hylas has performed well throughout its testing in orbit and is now ready for commercial service.

An extensive series of tests has checked the performance of its communications payloads. Conducted from ESA’s new testing facilities in Redu, Belgium, the tests have confirmed that the payload, including the antennas, is in good health, operating correctly and shows no ill effects from space.


“The test plan included a very wide range of different checks,” explained Andrew Murrell, ESA’s Hylas-1 Payload Manager. “We also demonstrated the payload’s unique ‘highly flexible’ capabilities.”

The innovative ‘highly adaptable’ payload was developed by Astrium (UK), with the assistance of ESA’s Advanced Research in Telecommunication Systems (ARTES) programme. ESA has devoted years to developing satellite broadband technologies through ARTES, and now several of these innovations are being put to work on Hylas-1.

The Hylas-1 Payload In Orbit Test (IOT) programme was conducted at ESA's centre at Redu, Belgium

“We've helped to develop and demonstrate in-orbit an entirely new architecture of communications payload, using a range of 'first-flight' technologies,” said Andrew.

“Of the 66 active units forming the payload, 48 were developed under this project.“

Providing European broadband coverage as well as TV distribution and other services, Hylas-1 is the first European satellite specifically designed to provide interactive broadband services, as ESA’s first public–private partnership in a full satellite system.

Hylas during Integrated System Tests

The bulk of the mission is financed by commercial operator Avanti Communications.

“The in-orbit testing of Hylas-1 has been a complete success and puts us in a strong position for future growth,” said David Williams, Chief Executive of Avanti Communications.

"With Europe’s first fully operational broadband satellite, Avanti will now provide a range of satellite data communications services to consumers, enterprise and governmental organisations across the UK and Europe.

Hylas-1 during final antenna tests in the ISRO Test Range

"With Europe’s first fully operational broadband satellite, Avanti will now provide a range of satellite data communications services to consumers, enterprise and governmental organisations across the UK and Europe.

Arianespace Hylas-1 Launch Poster

“In such a vast market with so much growth in data demand, and a strong customer base already committed, we are highly confident of achieving rapid commercial success for this powerful and flexible satellite.”

For more information, see the links in the links below:

Telecommunications and Integrated Applications:

Hylas-1 launch:

Images, Text, Credits: ESA / ISRO / Arianespace.


Einstein's Theory Fights Off Challengers

NASA - Chandra X-Ray Observatory logo.

March 24, 2011

Two new studies have put Einstein's General Theory of Relativity to the test like never before, using observations of galaxy clusters to study the properties of gravity on cosmic scales. These results, made using data from NASA's Chandra X-ray Observatory, show Einstein's theory is still the best game in town. Such studies are crucial for understanding the evolution of the universe, both in the past and the future, and for probing the nature of dark energy, one of the biggest mysteries in science.

This composite image of the Abell 3376 galaxy cluster shows X-ray data from the Chandra X-ray Observatory and the ROSAT telescope in gold, an optical image from the Digitized Sky Survey in red, green and blue, and a radio image from the VLA in blue. The bullet-like appearance of the X-ray data is caused by a merger, as material flows into the galaxy cluster from the right side. The giant radio arcs on the left side of the image may be caused by shock waves generated by this merger.

Chandra observations of galaxy clusters have previously been used to show that dark energy has stifled the growth of these massive structures over the last 5 billion years and to provide independent evidence for the existence of dark energy by offering a different way to measure cosmic distances.

Image, Text, Credits: X-ray (NASA / CXC / SAO / A. Vikhlinin; ROSAT), Optical (DSS), Radio (NSF / NRAO / VLA / IUCAA / J.Bagchi).


mercredi 23 mars 2011

Radioactivity in Switzerland: Swiss Air Force Tiger has made upper-air measurements

Swiss Air Force - F-5E Tiger patch.

March 24, 2011

Since the military airfield of Payerne, the jet climbed to 6000 meters to measure the radioactivity as the cloud from Japan might contain. Particle filters will be analyzed by the Federal Office of Public Health. The results will be announced Friday morning.

The F-5E Swiss Air Force, returning to the base of Payerne

At 11 h 15 this morning, an F-5E Tiger Swiss Army landed on the runway at Payerne front swiss TV camera. For Colonel Thierry Goetschmann, yet it is a routine flight. Six times per year, from April to October, it is flying at the request of the Federal Office of Public Health (BAG) to measure the presence of radioactive particles into the air. At the announcement of the arrival in Europe of the radioactive cloud Japanese, FOPH organized special flights until Friday and possibly next week.

The plane is heading toward a hangar where mechanics are expecting remove the two tubes attached under his wings. Bare hands, the two men out of metal mesh cylinders on which are fixed two blotters: they are particle filters. The simplest way, they bend over backwards and slipped in two large envelopes they then submit to Philip Steinmann, Deputy Head of Section Environmental Radioactivity in the BAG.

Video below: Story of Christian Doninelli for Swiss Television (in French):


This afternoon, in his laboratory Oberland (Canton of Bern), the scientist will submit these two filters on a gamma detector, for 24 h Journal: "We may find traces of Cesium 137 from the central Japan. Or perhaps in the upper-air measurements that we do tomorrow and Friday, said Philippe Steinmann. But I do not expect dangerous results for the population. "Then why are these measures? "Especially knowing the dispersion of the cloud and see where it goes."

The BAG will publish the results of measurements on his site:

Images, Text, Credits: Jean-Paul Guinnard / 24 Heures / TSR.

Article original en français:


A Very Cool Pair of Brown Dwarfs

ESO - European Southern Observatory logo.

23 March 2011

The coolest pair of brown dwarfs

Observations with the European Southern Observatory’s Very Large Telescope, along with two other telescopes, have shown that there is a new candidate for the coldest known star: a brown dwarf in a double system with about the same temperature as a freshly made cup of tea — hot in human terms, but extraordinarily cold for the surface of a star. This object is cool enough to begin crossing the blurred line dividing small cold stars from big hot planets.

Brown dwarfs are essentially failed stars: they lack enough mass for gravity to trigger the nuclear reactions that make stars shine. The newly discovered brown dwarf, identified as CFBDSIR 1458+10B, is the dimmer member of a binary brown dwarf system located just 75 light-years from Earth [1].

The brown dwarf binary CFBDSIR 1458+10

The powerful X-shooter spectrograph on ESO’s Very Large Telescope (VLT) was used to show that the composite object was very cool by brown dwarf standards. "We were very excited to see that this object had such a low temperature, but we couldn’t have guessed that it would turn out to be a double system and have an even more interesting, even colder component," said Philippe Delorme of the Institut de planétologie et d’astrophysique de Grenoble (CNRS/Université Joseph Fourier), a co-author of the paper. CFBDSIR 1458+10 is the coolest brown dwarf binary found to date.

The dimmer of the two dwarfs has now been found to have a temperature of about 100 degrees Celsius — the boiling point of water, and not much different from the temperature inside a sauna [2]. “At such temperatures we expect the brown dwarf to have properties that are different from previously known brown dwarfs and much closer to those of giant exoplanets — it could even have water clouds in its atmosphere," said Michael Liu of the University of Hawaii’s Institute for Astronomy, who is lead author of the paper describing this new work. "In fact, once we start taking images of gas-giant planets around Sun-like stars in the near future, I expect that many of them will look like CFBDSIR 1458+10B."

Wide-field view of the sky around the brown dwarf binary CFBDSIR 1458+10

Unravelling the secrets of this unique object involved exploiting the power of three different telescopes. CFBDSIR 1458+10 was first found to be a binary using the Laser Guide Star (LGS) Adaptive Optics system on the Keck II Telescope in Hawaii [3]. Liu and his colleagues then employed the Canada–France–Hawaii Telescope, also in Hawaii, to determine the distance to the brown dwarf duo using an infrared camera [4]. Finally the ESO VLT was used to study the object’s infrared spectrum and measure its temperature.

ESO - Zooming in on the brown dwarf binary CFBDSIR 1458+10
The hunt for cool objects is a very active astronomical hot topic. The Spitzer Space Telescope has recently identified two other very faint objects as other possible contenders for the coolest known brown dwarfs, although their temperatures have not been measured so precisely. Future observations will better determine how these objects compare to CFBDSIR 1458+10B. Liu and his colleagues are planning to observe CFBDSIR 1458+10B again to better determine its properties and to begin mapping the binary's orbit, which, after about a decade of monitoring, should allow astronomers to determine the binary’s mass.


[1] CFBDSIR 1458+10 is the name of the binary system. The two components are known as CFBDSIR 1458+10A and CFBDSIR 1458+10B, with the latter the fainter and cooler of the two. They seem to be orbiting each other at a separation of about three times the distance between the Earth and the Sun in a period of about thirty years.

[2] By comparison the temperature of the surface of the Sun is about 5500 degrees Celsius.

[3] Adaptive optics cancels out much of Earth’s atmospheric interference, improving the image sharpness by a factor of ten and enabling the very small separation binary to be resolved.

[4] The astronomers measured the apparent motion of the brown dwarfs against the background of more distant stars caused by Earth's changing position in its orbit around the Sun. The effect, known as parallax, allowed them to determine the distance to the brown dwarfs.
More information

This research was presented in a paper, “CFBDSIR J1458+1013B: A Very Cold (>T10) Brown Dwarf in a Binary System”, Liu et al. to appear in the Astrophysical Journal.

The team is composed of Michael C. Liu (Institute for Astronomy [IfA], University of Hawaii, USA), Philippe Delorme (Institut de planétologie et d’astrophysique de Grenoble, CNRS/Université Joseph Fourier, France [IPAG]), Trent J. Dupuy (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), Brendan P. Bowler (IfA), Loic Albert (Canada-France-Hawaii Telescope Corporation, Hawaii, USA), Etienne Artigau (Université de Montréal, Canada), Celine Reylé (Observatoire de Besançon, France), Thierry Forveille (IPAG) and Xavier Delfosse (IPAG).

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. 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 VISTA, the world’s largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.


    * Research paper:
    * Photos of the VLT:

Images, Text, Credits: ESO / L. Calçada / Michael Liu, University of Hawaii / Digitized Sky Survey 2. Acknowledgement: Davide de Martin / Video: ESO / A. Fujii/Digitized Sky Survey 2. Music: John Dyson (from the album Moonwind).

Best regards,

mardi 22 mars 2011

Disappearing Act

NASA - Spitzer Space Telescope logo.

March 22, 2011

This swirling landscape of stars is known as the North America Nebula. In visible light, the region resembles North America, but in this new infrared view from NASA's Spitzer Space Telescope, the continent disappears.

Where did the continent go? The reason you don't see it in Spitzer's view is due, in part, to the fact that infrared light can penetrate dust whereas visible light cannot. Dusty, dark clouds in the visible image become transparent in Spitzer's view. In addition, Spitzer's infrared detectors pick up the glow of dusty cocoons enveloping baby stars.

Clusters of young stars (about one million years old) can be found throughout the image. Slightly older but still very young stars (about 3-5 million years) are also liberally scattered across the complex. Some areas of this nebula are still very thick with dust and appear dark even in Spitzer's view and are likely to be the youngest stars in the complex (less than a million years old).

Images, Text, Credits: NASA / JPL-Caltech.


lundi 21 mars 2011

Mars500 video diary 12: It is finally (and it was) Mars!

ESA -  ROSCOSMOS Mars500 Mission patch.

21 March 2011

The highlight of the Mars500 was landing to Mars. Diego and Romain are showing in this long video all what happened during exiting February at the Mars500 modules.

The Mars500 crew arrived virtually at Mars on 1 February and - as the mission description goes - docked there with a lander, found it full of cargo and transferred it to their spacecraft. After careful preparations three crewmembers (Diego Urbina, Alexandr Smoleevskiy and Wang Yue) entered the lander on 8 February and they 'landed' on Mars. Romain Charles, Alexey Sitev and Sukhrob Kamolov continued to 'orbit' Mars and followed their friends as they made three 'Marswalks', then rejoined them on 27 February after 'docking' with the orbital vehicle.

This video is a compilation of the material they recorded during this key period of the Mars500 isolation study.

Related links:

Mars500 quick facts:

Mars500 crew:


Institute of Biomedical Problems (IBMP):

Mars500 (IMBP):

Image, Video, Text, Credits: ESA / ESA on Youtube.


Simulations of atmospheric dispersion of the plume formed by the release of the Fukushima Daiichi Nuclear Power Station

IRSN logo labeled.

March 21, 2011, (March 19 release).

Simulations of atmospheric dispersion of the plume formed by the release of the Fukushima Daiichi Nuclear Power Station, between March 12 and March 20, 2011

1 - What is known radioactive releases issued since March 12, 2011?

The IRSN has no direct measurement data on the composition and extent of radioactive releases, but has technical information on facilities rugged.

The interpretation of this information has enabled the IRSN to develop likely scenarios of degradation of three reactors since March 12, ensuring their consistency with the measurements of dose rate obtained on the site. IRSN also retained the assumption that these discharges will continue until March 20.

The radioactive elements released during various episodes of rejection are rare gases (radioactive elements chemically very reactive, remaining in the atmosphere without being deposited on the ground) and volatile elements, mainly from radioactive iodine, including iodine-131 which has a half life of 8 days, and radioactive cesium, which cesium 137.

2 - The dispersion of radioactive releases into the atmosphere

IRSN simulated atmospheric dispersion of releases estimated between 12 and 22 March, using its numerical model applicable to long distance (scale of several hundred kilometers), using observations and weather forecasts provided by Weather France.

This simulation was applied to the cesium 137, as a tracer of the plume during this period. The modeling results are expressed in becquerels of cesium-137 per cubic meter of air (Bq / m 3):

Watch the simulation of the plume

This modeling performed throughout Japan shows that the plume has led in directions that have varied over time: first north-east until March 14, then south and southeast west toward Tokyo, March 15, then east toward the Pacific Ocean.

IRSN compared the simulation results with the results of measurements of air contamination carried in Tokyo. They are the same order of magnitude as the values ​​measured in this city, as shown in the charts below for iodine 131 and cesium 137.

This comparison allows us to consider that the air dispersion modeling performed by IRSN to produce satisfactory results for the agglomeration of Tokyo and the doses calculated by IRSN from this modeling are representative of the doses may have been received by the population exposed to the radioactive plume.

Evolution of the activity of Cesium 137 and Iodine 131 measured in air of Tokyo March 15 to 17 (local time)

Concentration of Cesium 137 and Iodine-131 in the air of Tokyo calculated by IRSN by modeling the long-range atmospheric dispersion

3 - Estimation of doses likely to be received by persons exposed to the radioactive plume

IRSN said the doses likely to be received by a person exposed to the radioactive plume, assuming it stays in one place and unprotected (outside) from March 12 to 22. For these dose calculations, the SNRIs considered a child of a year which is most sensitive to iodine 131 (thyroid dose).

The following simulations show the evolution of doses over time, the simulation period. If new releases were to occur in the future, these rates may increase further in the absence of protection for those most at risk.

Whole body dose may be received by a child of 1 year in the absence of protection for releases:

Watch the simulation

In case of accident, the values ​​of whole-body doses from which protective actions are recommended are 10 mSv for sheltering in place and 50 mSv for evacuation. Below 10 mSv, the health risk is considered low enough not to make the necessary protective actions. For comparison, the average annual dose received in France due to natural radioactivity and medical exposure is 3.7 mSv.

Thyroid doses could be received by a child of 1 year in the absence of protection for releases:

Watch the simulation

In case of accident, the dose values ​​from which the ingestion of stable iodine is recommended in Japan is 100 mSv.

4 - Modeling the dispersion of radioactive releases into the atmosphere on a global scale

From the estimated releases from IRSN, Meteo France has simulated the dispersion of radioactive releases from great distances, projected until March 26:


According to this simulation, the plume would now reached the north-eastern Siberia, the United States and western Atlantic. It should reach France from 23 or 24 March.

Merger expected to run from this model could be of the order of 0,001 Bq / m 3 in France and the overseas departments of the northern hemisphere. As expected, the southern hemisphere is not significantly affected by this large-scale dispersal.

For comparison, values ​​measured in the days following the Chernobyl accident had exceeded 100 000 Bq / m 3 in the first few kilometers around the plant and they were in the range of 100 to 1000 Bq / m 3 in the country most affected by the plume (Ukraine, Belarus); France, values ​​measured in the east were the order of 1 to 10 Bq/m3 (May 1, 1986). Today, a very low activity of cesium-137 remains in the air, on the order of 0.000001 Bq/m3.

Monitoring of radioactivity in the air in France

IRSN provides several maps to obtain the results of measurement of radioactivity in air:

   - In France:
   - To Saint Pierre et Miquelon:
   - Tahiti:
   - Guyana:
   - Guadeloupe:
   - In Martinique:
   - La Reunion
   - In New Caledonia:

For more informations about IRSN, visit (in French):

Images, Animations, Text, Credit: Institute of Radiation Protection and Nuclear Safety (IRSN) / Météo France / Translation:

NB: The IRSN is not responsible for any incorrect translations.


dimanche 20 mars 2011

KIZUNA's Support Activities for Disaster-stricken Areas after Tohoku Region Pacific Ocean Coastal Earthquake

JAXA logo labeled.

March 20, 2011 (JST)

The Japan Aerospace Exploration Agency (JAXA) has established a broadband environment using the wideband Internetworking Engineering Test and Demonstration Satellite "KIZUNA" (WINDS) as support for disaster measures for areas stricken by the Tohoku Region Pacific Ocean Coastal Earthquake.

The National Institution of Information and Communications Technology (NICT) has set up a high definition teleconference system using the KIZUNA between Kesennuma City (Fire Department Headquarters), Miyagi Prefecture, and the Tokyo Fire Department (TFD, at its Headquarters' strategy room), following TFD's request. High definition teleconferences, which enable real-time information sharing that is necessary for support activities in disaster-stricken areas, have been conducted since March 15.

Based on a request from the Ministry of Education, Culture, Sports, Science and Technology, which received a petition from Iwate Prefecture, JAXA installed a movable ground antenna for the KIZUNA at the Iwate Prefectural Office (Disaster measures headquarters) and also in Kamaishi City (Local disaster measures office). Broadband lines were connected on March 20, and high definition teleconference systems, IP telephones, and radio LANs became available.

The following is the current status

JAXA and NICT will continue to work to establish broadband environments in disaster-stricken areas for swift information sharing of current conditions and the needs of each area. JAXA and NICT has been engaging in the technological development of broadband satellite communications using the KIZUNA that can assist in disaster measures, and the support activity this time is part of our development efforts.

Image above: Ground antenna (movable VSAT) installed at the Iwate Prefectural Office (Antenna diameter 1.0 m).

Mission website:

Wideband InterNetworking engineering test and Demonstration Satellite "KIZUNA" (WINDS):

Images, Text, Credits: Japan Aerospace Exploration Agency (JAXA) / National Institution of Information and Communications Technology (NICT).