vendredi 3 août 2012

Final cry of disrupted star points to site of oblivion












ESA - XMM-Newton Mission patch.

03 Aug 2012

Astronomers have detected tell-tale luminosity fluctuations in the X-ray signal from a star that was torn apart and devoured by the supermassive black hole at the centre of a distant galaxy. The fluctuations, which have a period of 200 seconds, originate from the innermost stable orbit around the black hole and represent the last signal sent by the debris of the disrupted star before disappearing beyond the black hole's event horizon. The discovery, based on data from ESA's XMM-Newton and the Japan/US Suzaku space observatories, has allowed astronomers to probe the details of matter accretion onto a supermassive black hole in the distant Universe for the first time.

Black holes exist on a variety of scales, from the stellar-mass ones that derive from the collapse of massive stars to the supermassive black holes that reside at the centre of most galaxies and have masses that are millions or even billions of times larger than the Sun's. Regardless of their mass, the phenomena that arise in the proximity of these extremely dense and compact objects due to their intense gravitational fields are quite similar. An effect of the accretion of the surrounding matter onto a black hole is the emission of radiation across the electromagnetic spectrum, which has been detected and studied extensively around stellar-mass and supermassive black holes alike. These observations allow astronomers to probe the behaviour of gravity in its strongest regime and to test general relativity in a wide range of environments, both in our Galaxy (the Milky Way) and in more distant galaxies.


Artist's impression of the debris of a disrupted star being accreted by a supermassive black hole. Credit: NASA's Goddard Space Flight Center.

 A small fraction of the supermassive black holes hosted at the centre of galaxies are undergoing 'active' accretion and feeding on a supply of gas at tremendous rates – these are the so-called active galactic nuclei (AGN). However, the majority of supermassive black holes, including the one at the centre of the Milky Way, are in a dormant state and only accrete matter on rare occasions, when a star happens to pass too close to it. In this case, matter on the side of the star facing the black hole experiences a stronger pull with respect to the other side, and this eventually tears the star apart. This phenomenon, referred to as tidal disruption, temporarily switches on the black hole's activity: debris from the shattered star starts orbiting around the black hole in a disc and part of it is rapidly accreted, causing a sudden boost in the luminosity of the galaxy's centre, especially at the highest energies.

Tidal disruption has been spotted in several galaxies in recent years, but the first case of such an event to be observed since its very onset was discovered only in 2011. Originally detected as a gamma-ray burst (GRB) by the NASA satellite Swift, the source, named Sw J1644+57, remained exceptionally bright for a few weeks after its discovery, unlike any other known GRB. After further observations, astronomers were able to link the flaring source to a star that was being disrupted and subsequently devoured by the supermassive black hole at the centre of a distant galaxy.

"The first observations of this intriguing object revealed that, besides being unusually bright, it also displayed rather curious variability," comments Rubens Reis from the University of Michigan, USA. Reis led a study of the luminosity fluctuations of Sw J1644+57, whose results are published online on 2 August 2012 in the journal Science. "We thus exploited target of opportunity observations on the ESA XMM-Newton and the Japan/US Suzaku X-ray observatories to study this source and investigate the origin of its variability," he adds. In particular, XMM-Newton was used to monitor the source for several months.

According to the data collected by Reis and his collaborators, Sw J1644+57 exhibits what astronomers call quasi-periodic oscillations: luminosity fluctuations that occur in a regular fashion but are only seen for a certain period of time before disappearing. In this particular case, the oscillations have a very short period – about 200 seconds – and were only detected in the first observations from both XMM-Newton and Suzaku, which were performed a few days after the discovery of the flare.

XMM-Newton Space Telescope

"When we see a cosmic source undergoing regular variations, it usually means that something exciting is taking place in its vicinity," explains Reis. In particular, quasi-periodic oscillations are known to arise in a very special site around a black hole: the so-called innermost stable circular orbit, which depends on the black hole's mass and spin and defines its range of action. At distances larger than this limiting orbit, matter can revolve around the black hole on stable trajectories, but anything located within this orbit will inexorably precipitate towards the black hole and be quickly accreted onto it. "The quasi-periodic oscillations we detected in Sw J1644+57 tell us that the flare was produced by matter on the edge of an accretion disc around the black hole. This was the last signal that we received from the debris of the disrupted star before being engulfed and disappearing beyond the black hole's event horizon," notes Reis.

Astronomers have identified quasi-periodic oscillations in several stellar-mass black holes across the Galaxy, but so far they had only spotted them once in the vicinity of a supermassive black hole. The discovery of quasi-periodic oscillations in the nearby, AGN-hosting galaxy RE J1034+396, in 2008, was also made with XMM-Newton. "With its large collecting area, XMM-Newton provides us with high signal-to-noise data, thus making it possible to unambiguously identify fluctuations and to detect quasi-periodic oscillations even in the faint light from other galaxies," comments Norbert Schartel, XMM-Newton Project Scientist at ESA.

Sw J1644+57 is the second supermassive black hole in the proximity of which quasi-periodic oscillations have been seen, and the first one hosted in a galaxy that is at a cosmologically significant distance from us – its light having travelled for over 3 billion years before reaching us. "The discovery confirms once more the scale-invariant nature of accretion onto black holes: no matter what their mass is, these compact objects give rise to the same physical processes," says Reis. Besides, having observed the same phenomenon both in a nearby and a distant galaxy indicates that the mechanisms underlying black hole accretion have not changed across the past few billion years of cosmic history. "With this finding, we are finally able to probe the predictions from general relativity in great detail beyond the local Universe," Reis concludes.

Notes for editors:

The findings presented here are based on a series of 12 observations of the source Sw J1644+57 performed with ESA's XMM-Newton X-ray observatory, as well as on one observation performed with the Japan/US Suzaku X-ray observatory .

Sw J1644+57 was discovered on 28 March 2011 by the Burst Alert Telescope (BAT) on board NASA's Swift space observatories and was originally identified as a gamma-ray burst (GRB). However, unlike any other known GRB, the source remained exceptionally bright and highly variable for several weeks. Further observations across the electromagnetic spectrum associated the event with the centre of a small, star-forming galaxy at redshift z~0.35. The flare appears to be due to a tidal disruption event, during which the dormant supermassive black hole at the centre of the galaxy has torn apart and accreted a star.

The XMM-Newton monitoring began about 19 days after the detection of the source and consisted of 12 bi-weekly observations at energies between 0.2 and 10 keV. The team of astronomers also used one Suzaku observation, performed in the same energy range about 9 days after the source was detected.

Related publications:

R. Reis, et al., "A 200-s quasi-periodicity following the tidal disruption of a star by a dormant black hole", 2012, Science, published online on 2 August 2012; DOI: 10.1126/science.1223940.

Related links:

XMM-Newton Science Operations Centre: http://xmm.esac.esa.int/ and http://sci.esa.int/science-e/www/area/index.cfm?fareaid=23

Images, Text, Credit: ESA / Norbert Schartel / University of Michigan / Rubens C. Reis / NASA's Goddard Space Flight Center.

Greetings, Orbiter.ch

Mars Express marks the spot for Curiosity landing












ESA - Mars Express Mission patch.

3 August 2012

 Gale Crater

Much like a treasure map branded with an ‘X’ to mark the site of buried bounty, NASA’s rover Curiosity will be targeting its very own ‘X’ inside Gale Crater, to seek out the signs of past water – and maybe even life – on the Red Planet.

Mars Express will play an important role in monitoring the spectacular delivery of Curiosity to the martian surface during the ‘seven minutes of terror’ that describe the entry, descent and landing of the car-sized rover.

But the ESA spacecraft has already provided information that led to refinements of the rover’s landing ellipse last month. 

Revised landing target for Curiosity

Part of NASA’s Mars Science Laboratory (MSL) mission, Curiosity was initially aiming for a 20 x 25 km landing ellipse, already much smaller than the landing target area for any previous Mars mission thanks to MSL’s techniques for improved landing precision.

By combining elevation data from the High Resolution Stereo Camera on Mars Express, image data from the Context Camera on NASA's Mars Reconnaissance Orbiter, and colour information from Viking Orbiter imagery, the target ellipse was adjusted to just 20 x 7 km.

Curiosity targets ellipse near Gale's mountain

This shifts the centre of the ellipse closer to the mountain inside the 154 km-wide Gale Crater.

Rover delivered by skycrane

The central mound – known informally as Mount Sharp – rises 5.5 km above the crater floor and is the prime destination of Curiosity.

Orbiting spacecraft have already identified minerals and clays there that suggest water may have once filled the area, and as Curiosity slowly makes its ascent, it will analyse samples of these materials with its onboard laboratory in search of its own treasure: the building blocks of life.

Timeline: ESA tracks MSL arrival at Mars

The highlight of ESA’s support for NASA’s Curiosity landing happens at 06:29 on Monday, 6 August, when the Mars Express Lander Communication (MELACOM) system is switched on.

Mars Express

Recording of the radio signals transmitted by the Mars Science Laboratory (MSL) is planned to begin at 07:09 and end at 07:37 (all times shown as ground event time in CEST).

ESA’s ground tracking station in New Norcia, Australia, will also listen and record signals from the NASA mission at the same time.

New Norcia station

At 08:15, Mars Express will contact Earth via ESA’s 35 m deep space station at New Norcia, and begin transmitting the recorded information, which should take about 11 minutes to download; signals will take nearly 14 minutes to cover the 248 million km distance to Earth.

The transfer will be complete by about 08:26; the data will be transferred in real time to ESOC, and made immediately available to NASA’s MSL mission team at the Jet Propulsion Lab in California.

Notes:

CEST = UTC + 2 hours
Earth time = Mars time + 13min:48sec
MEX: Mars Express
MSL: Mars Science Laboratory
NNO: ESA New Norcia station
AOS: Acquisition of signal
S/C: Spacecraft
All times subject to change


More information:

NASA MSL mission at JPL: http://marsprogram.jpl.nasa.gov/msl/

NASA - Mars Science Laboratory: http://www.nasa.gov/mission_pages/msl/index.html

Video: Curiosity's Seven Minutes of Terror: http://www.nasa.gov/multimedia/videogallery/index.html?media_id=146903741

Mars Express: http://www.esa.int/SPECIALS/Mars_Express/index.html

Mars Express blog: http://blogs.esa.int/mex

Mars Webcam: http://www.esa.int/vmc

Credits: ESA / Alex Lutkus / DLR / FU Berlin (G. Neukum) / NASA / JPL-Caltech / lMSSS.

Best regards, Orbiter.ch

Star Formation in a Dwarf Galaxy














NASA - SPITZER Space Telescope patch / ESA - HERSCHEL Mission patch.

August 3, 2012


This image shows the Small Magellanic Cloud galaxy in infrared light from the Herschel Space Observatory, a European Space Agency-led mission, and NASA's Spitzer Space Telescope. Considered dwarf galaxies compared to the big spiral of the Milky Way, the Large and Small Magellanic Clouds are the two biggest satellite galaxies of our home galaxy.

In combined data from Herschel and Spitzer, the irregular distribution of dust in the Small Magellanic Cloud becomes clear. A stream of dust extends to the left in this image, known as the galaxy's "wing," and a bar of star formation appears on the right.

The colors in this image indicate temperatures in the dust that permeates the Cloud. Colder regions show where star formation is at its earliest stages or is shut off, while warm expanses point to new stars heating surrounding dust. The coolest areas and objects appear in red, corresponding to infrared light taken up by Herschel's Spectral and Photometric Imaging Receiver at 250 microns, or millionths of a meter. Herschel's Photodetector Array Camera and Spectrometer fills out the mid-temperature bands, shown here in green, at 100 and 160 microns. The warmest spots appear in blue, courtesy of 24- and 70-micron data from Spitzer.

For more information about HERSCHEL, visit: http://www.esa.int/SPECIALS/Herschel/index.html

For more information about SPITZER, visit: http://www.nasa.gov/mission_pages/spitzer/main/index.html

Image, Text, Credits: ESA / NASA / JPL-Caltech / STScI.

Greetings, Orbiter.ch

jeudi 2 août 2012

Arianespace makes history by orbiting Intelsat 20 and HYLAS 2 on Ariane 5’s 50th consecutive success





















ESA / ARIANESPACE - Flight VA208 mission poster / ARIANESPACE - Ariane 5 - 50 Successes in a Row patch.

August 2, 2012

Ariane Flight VA208

Ariane 5 ECA ready for launch

Arianespace’s mission that orbited the Intelsat 20 and HYLAS 2 satellites today marked the milestone 50th consecutive success for its Ariane 5 heavy-lift launcher, confirming this vehicle’s role as the launch services industry reference in reliability, flexibility and performance.

video
Ariane 5 ECA flight VA208 launch

With the deployment of its latest two passengers during a flight of 34 minutes from the Spaceport in French Guiana, Ariane 5’s combined lift performance in the 50 straight successes totals more than 434,000 kg., delivering payloads to geostationary transfer orbit, low Earth orbit, Sun-synchronous polar orbit and Earth escape trajectories.

HYLAS 2 satellite

Payloads carried by Ariane 5 have included civilian and defense telecommunications satellites, TV broadcast relay platforms, resupply vessels for the International Space Station, civilian and military Earth observation systems, meteorology and environmental spacecraft and deep-space exploration probes; along with auxiliary and piggyback payloads for scientific and industrial experiments, for defense early warning, electronic intelligence (ELINT) and climate research.

Intelsat 20 satellite

Recognizing those who contribute to Ariane 5’s success

In post-launch comments from the Spaceport, Arianespace Chairman & CEO Jean-Yves Le Gall paid homage to all who contribute to Ariane 5’s successes, from the mission personnel in Europe and the launch teams in French Guiana to Europe’s industrial suppliers, as well as the European Space Agency and France’s CNES space agency – which have played key roles in the launcher’s development and operation.

“Thanks to all you in Europe and French Guiana, Ariane 5 is something that works…works very well…and will continue to work for a long time,” he added.  “Following tonights launch, and with all of the contracts we’ve signed since the start of this year, our order book effectively covers no less than 19 firm Ariane 5 launches, which guarantees us more than three years of activity.  Therefore, thank you and bravo to everyone!”

The numbers from Ariane 5’s unbroken string of 50 mission successes are impressive.

In its most frequent role as the launcher of choice for telecommunications and TV broadcast satellite operators and manufacturers worldwide, Ariane 5 has delivered platforms with a total equivalent relay capacity of well over 3,200 transponders, channels and beams for both civil and military users.

Ariane 5 on the launch-pad

The largest payload lofted by Ariane 5 is Europe’s Automated Transfer Vehicle for servicing of the International Space Station, with the heaviest of the three orbited so far weighing more than 19,700 kg.; while the smallest were piggyback satellites such as Spain's Nanosat, with had a liftoff mass of less than 20 kg.

Le Gall said today’s mission also was historic from another aspect, as its lift performance of nearly 10.2 metric tons beat the world’s record for total mass launched to geostationary transfer orbit.  “We captured the previous record last year with just over 10 tons, and this demonstrates the pertinence of our improvement strategy, which – step-by-step – enables us to increase the capacity of our launcher while retaining its extraordinary reliability.”

Intelsat 20 was installed as the upper payload on this latest Ariane 5 launch, and was released first during the mission at 28 minutes into the flight.  Built for international satellite operator Intelsat by Space Systems/Loral of Palo Alto, California based on its 1300-series platform, Intelsat 20 weighed approximately 6,090 kg. at liftoff, and is configured with Ku-band, C-band and Ka-band transponders.  Intended to replace the Intelsat 7 and Intelsat 10 satellites in orbit, Intelsat 20 is to provide video, telephone and data transmission services for Europe, Africa, Russia, Asia and the Middle East.     

Two key customers on Ariane 5’s milestone mission

According to Le Gall, today marks the 53rd time Intelsat has placed its confidence in Arianespace’s launch services.  “In fact, more than one payload in six launched by Ariane vehicles from the beginning have been for Intelsat,” he continued.  “This proves, more than any words, the quality and intensity of our relationship.  And with a satellite as powerful as Intelsat 20, built by Space Systems/Loral, we are certain that Intelsat will be able to respond to the growing demands of its customers – in particular for the African continent.”

The HYLAS 2 satellite orbited by Ariane 5 on today’s flight was deployed 34 minutes after liftoff, and will be used by European satellite operator Avanti Communications.  Produced by Orbital Sciences Corporation of Dulles, Virginia using the Star 2.4E platform, HYLAS 2 is equipped with Ka-band transponders for data capacity offered to telecommunications, enterprise and government customers in Europe, the Middle East and portions of Africa.

Photo collage highlighting the 50 consecutive Ariane 5 successes

Le Gall noted that Arianespace orbited Avanti Communications’ first satellite – HYLAS 1 – on an Ariane 5 mission in 2010.  “We are very proud that to have been chosen by Avanti in contributing to the development of very high-speed data services,” he added.

The Arianespace mission pace will continue with its next two flights announced for September: the September 21 launch of another Ariane 5 from the Spaceport with the Astra 2F and GSAT-10 telecommunications relay platforms; and the September 16 mission of a Soyuz from Baikonur Cosmodrome in Kazakhstan, performed by Arianespace's Starsem affiliate and carrying Eumetsat's MetOp-B meteorological satellite.

    See the photo collage highlighting the 50 consecutive Ariane 5 successes:
http://www.arianespace.com/news-feature-story/2012/8-2-2012-50th-success-launch.asp

    See the Arianespace launch kit for further details:
http://www.arianespace.com/news-launch-kits/2011-present-archive.asp

    Related links:

    Avanti Communications HYLAS 2 launch website: http://www.avantiplc.com/hylas2/#

    Avanti Communications corporate website: http://www.avantiplc.com/

    Orbital Sciences Corporation website: http://www.orbital.com/

    Intelsat website: http://www.intelsat.com/

    Space Systems/Loral website: http://www.ssloral.com/

Images, Video, Text, Credits: Arianespace / Intelsat / Orbital.

Greetings, Orbiter.ch

ATLAS and CMS submit Higgs-search papers












CERN - European Organization for Nuclear Research logo.

2 August 2012


Graphic above: Protons collide in the CMS detector at 8 TeV, forming Z bosons which decay into electrons (green lines) and muons (red). Such an event is compatible with the decay of a Standard Model Higgs boson (Image: CMS).

The ATLAS and CMS collaborations today submitted papers to the journal Physics Letters B outlining the latest on their searches for the Higgs boson. The teams report even stronger evidence for the presence of a new Higgs-like particle than announced on 4 July.


Graphic above: Protons collide in the ATLAS detector, producing two pairs of electrons (red and blue). Such an event is compatible with the decay of a Higgs boson (Image: ATLAS).

On 4 July the experiments reported indications for the presence of a new particle, which could be the Higgs boson, in the mass region around 126 gigaelectronvolts (GeV). Both ATLAS and CMS gave the level of significance of the result as 5 sigma. On the scale that particle physicists use to describe the certainty of a discovery, one sigma means the results could be random fluctuations in the data, 3 sigma counts as evidence and a 5-sigma result is a discovery.

video
Video: What is the Higgs boson?

The CMS results reported today reach a significance of 5.0 sigma, and the ATLAS team's results reach 5.9 sigma. The value corresponds to a one-in-550 million chance that in the absence of a Higgs such a signal would be recorded.

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.

Find out more:

    ATLAS paper: http://arxiv.org/abs/1207.7214

    CMS paper: http://arxiv.org/abs/1207.7235

    About the Higgs boson: http://press.web.cern.ch/press/background/B01-Higgs_en.html

    Symmetrybreaking: Physicists show strengthened signals of Higgs-like particle: http://www.symmetrymagazine.org/breaking/2012/08/01/physicists-show-strengthened-signals-of-higgs-like-particle-in-publications/

Graphics, Video, Text, Credit: CERN.

Greetings, Orbiter.ch

Transport cargo ship Progress M-16M successfully docks with ISS










ROSCOSMOS - Russian Vehicles patch.

08/02/2012

On August 2, 5.18 cet carried out docking cargo vehicle (THC) Progress M-16M to the International Space Station (ISS).

Progress M-16M approaching ISS

THC docked to a docking bay (CO) Pirs. Convergence process was carried out in automatic mode controlled by the Mission Control Center specialists of FSUE TsNIIMash and Russian crew members of ISS cosmonauts Space Agency Gennady Padalka, Sergei and Yuri Malenchenko Revina.

video
Successful Fast Docking of Progress 48 (M-16M)

The ship delivered cargo to the station needed to keep the ISS in manned mode and the program of applied research on its board.

Among the goods - fuel, oxygen, water, equipment for scientific experiments ("Vizir", "MATI-75", "Relax," "SLS", "Vector-T", "Typology", "Aseptic", "Ginseng- 2 "," Cascade "," Biodegradation "," Coulomb crystal "), equipment for the Russian and American segments of the station, the means of medical support, as well as containers of food, expendables, etc.

Progress-M cutaway description

The total weight of all cargo delivered was 2639 kg.

The ISS crew continues to work 32/33-y long expedition in the commander Gennady Padalka, flight engineers Sergei Revina and Yuri Malenchenko (Federal Space Agency), NASA astronauts Joseph Acaba and Sanita Williams, Akihiko Hoshide (JAXA).

The launch of "truck" - the third this year. The previous were also successfully carried out January 26 (TGC "Progress M-14M") and April 20 (TGC "Progress M-15M").

Original text in Russian: http://www.federalspace.ru/main.php?id=2&nid=19383

Images, Video, Text, Credits: Press Service of the Russian Space Agency (Roscosmos PAO) / NASA TV / Mars Center, G. De Chara / Translation: Orbiter.ch.

Best regards, Orbiter.ch

The fractured features of Ladon basin












ESA - Mars Express Mission patch.

2 August 2012

 Ladon basin in full colour

ESA’s Mars Express has observed the southern part of a partially buried approx. 440-km wide crater, informally named Ladon basin. The images, near to where Ladon Valles enters this large impact region reveal a variety of features, most notably the double interconnected impact craters Sigli and Shambe, the basins of which are criss-crossed by extensive fracturing.

This region, imaged on 27 April by the high-resolution stereo camera on Mars Express is of great interest to scientists since it shows significant signs of ancient lakes and rivers.

Both Holden and Eberswalde Craters were on the final shortlist of four candidate landing sites for NASA’s Mars Science Laboratory, which is due now to land in Gale Crater on 6 August.

Large-scale overview maps show clear evidence that vast volumes of water once flowed from the southern highlands. This water carved Ladon Valles, eventually flowing into Ladon basin, an ancient large impact region. 

Sigli and Shambe perspective view

Elliptical craters like this 16 km-wide example are formed when asteroids or comets strike the surface of the planet at a shallow angle.

Scientists have suggested that a fluidised ejecta pattern indicates the presence of subsurface ice which melted during the impact. Subsequent impacts have created a number of smaller craters in the ejecta blanket.

Ladon basin in context

The interconnected craters Sigli and Shambe are thought to have formed later when an incoming projectile split into two pieces just before impact. The joined craters were then partly filled with sediments at some later epoch.

Ladon Basin perspective view

Deep fractures can be seen within the craters whilst in the central and right part of the image, smaller craters and more subtle curved fractures appear. These fractures on the basin floor extend beyond the image borders and form concentric patterns. The fractures are believed to have evolved by compaction of the huge sediment loads deposited within the impact basin.

Topographical view

The outflow of Ladon Valles in to Ladon basin is located towards the east of Sigli and Shambe Craters, towards the bottom of this image. Here, and in several other parts of the image, lighter-toned layered deposits can be seen. Researchers have detected clay minerals within these deposits, suggesting a relatively long-lasting presence of liquid water in the region’s past.

3D anaglyph view

In addition, winding, valley-like dendritic structures running into the larger basin can be seen above Sigli and Shambe Craters, running in to the larger impact basin, again indicating flowing water at some distant epoch.

Related links:

High Resolution Stereo Camera: http://berlinadmin.dlr.de/Missions/express/indexeng.shtml

Behind the lens: http://www.esa.int/SPECIALS/Mars_Express/SEMSXE1PGQD_0.html

Frequently asked questions: http://www.esa.int/SPECIALS/Mars_Express/SEM76D9OY2F_0.html

Mars Express in depth: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=9

Mars Express: http://www.esa.int/SPECIALS/Mars_Express/index.html

Mars Express blog: http://webservices.esa.int/blog/blog/7

Mars Webcam: http://www.esa.int/vmc

Images, Text, Credits: ESA / DLR /FU Berlin (G. Neukum) / NASA MGS MOLA Science Team.

Greetings, Orbiter.ch

mercredi 1 août 2012

Field of Stars












NASA - Hubble Space Telescope patch.

August 1, 2012


The Hubble Space Telescope captured a crowd of stars that looks rather like a stadium darkened before a show, lit only by the flash bulbs of the audience’s cameras. Yet the many stars of this object, known as Messier 107, are not a fleeting phenomenon, at least by human reckoning of time -- these ancient stars have gleamed for many billions of years.

Messier 107 is one of more than 150 globular star clusters found around the disc of the Milky Way galaxy. These spherical collections each contain hundreds of thousands of extremely old stars and are among the oldest objects in the Milky Way. The origin of globular clusters and their impact on galactic evolution remains somewhat unclear, so astronomers continue to study them.

Messier 107 can be found in the constellation of Ophiuchus (The Serpent Bearer) and is located about 20,000 light-years from our solar system.

French astronomer Pierre Méchain first noted the object in 1782, and British astronomer William Herschel documented it independently a year later. A Canadian astronomer, Helen Sawyer Hogg, added Messier 107 to Charles Messier's famous astronomical catalogue in 1947.

This picture was obtained with the Wide Field Camera of Hubble’s Advanced Camera for Surveys.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Md., conducts Hubble science operations. STScI is operated by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

For more information about the Hubble Space Telescope, visit: http://hubblesite.org/ and http://www.nasa.gov/hubble

ESA Hubble Space Telescope website: http://www.spacetelescope.org/

Image, Text, Credits: ESA / NASA.

Best regards, Orbiter.ch

Liftoff ILV Soyuz-U with THC Progress M-16M












ROSCOSMOS logo.

08/01/2012

 Liftoff!

In accordance with the flight program of the International Space Station August 1 in 23.35 GMT with a ground launch complex Baikonur cosmodrome launch rocket Soyuz-U to transport cargo vehicle (THC) Progress M-16M.

video
Liftoff ILV Soyuz-U with THC Progress M-16M

After separation from the regular third stage rocket, THC Progress M-16M launched into orbit Sputnik and adopted by the management of the Mission Control Center near Moscow TsNIIMash (Korolev).

Mission Control Center near Moscow TsNIIMash (Korolev) room

THC docked Progress M-16M to the module Pirs of the International Space Station scheduled for August 2 in 5.24 Moscow time on the fourth turn of the flight.

Progress Launch Profile

The ship delivered cargo to the station needed to keep the ISS in manned mode and the program of applied research on its board. Among the goods - fuel, water, food, equipment, systems management, communications and life support, supplies of compressed oxygen, medical equipment, personal hygiene and control of purity of the atmosphere and cleaning stations, equipment for scientific research and experiments, additional equipment for the Russian and segments of the American station, as well as parcels for the crew of the ISS.

Original text in Russian: http://www.federalspace.ru/main.php?id=2&nid=19382

Images, Video, Text, Credits: Press Service of the Russian Space Agency (Roscosmos PAO) / Roscosmos TV / NASA TV / Screen captures: Orbiter,ch / Translation: Orbiter.ch,

Greetings, Orbiter.ch

Cluster looks into waves in the magnetosphere's thin boundaries












ESA - Cluster II Mission patch.

01 Aug 2012

Exploiting a favourable configuration of ESA's Cluster mission spacecraft, scientists have detected and characterised lower hybrid drift waves, a special kind of plasma waves that develop in thin boundaries both in space and in the laboratory. The measurement of fundamental properties of these waves was possible when two of the spacecraft were flying very close to one another in the tail of Earth's magnetosphere. With wavelengths of about 60 km, these waves appear to play an important role in the dynamics of electrons and in the transfer of energy between different layers of plasma in the magnetosphere.

Like all planets with a magnetic field, Earth has a protective shield against the solar wind, the stream of charged particles released continuously by the Sun. This bullet-shaped bubble, called the magnetosphere, is forged by the interplay between the solar wind and our planet's magnetic field and is composed of plasma, a state of matter that consists of charged particles and ions rather than atoms or molecules. The shielding effect, however, is not complete: particles from the solar wind are able, under certain conditions, to leak into the magnetosphere, where they may be subsequently accelerated, giving rise to the spectacular phenomenon of aurorae.


Image above: Artist's impression of Cluster spacecraft flying through the thin boundary in the magnetotail. Credit: ESA/AOES Medialab.

 The detailed mechanisms that cause solar wind particles to enter the magnetosphere and to be accelerated to high energies are not yet fully understood. More generally, the mutual interaction between the various regions that make up the magnetosphere, populated by plasma with very different densities and energies, remains an open issue and is the subject of extensive investigations. Understanding these processes is of great importance in the context of space weather, which is crucial to the operation of space missions and telecommunications networks. Besides, similar processes also take place, in a scaled-down version, when plasma is artificially produced in the laboratory for a variety of Earth-bound applications – an example is the tokamak plasma employed in nuclear fusion research. Earth's magnetosphere provides scientists with a giant testbed to study the behaviour of plasma on different scales than those that can be tackled in the laboratory.

In the magnetosphere, interactions are not a trivial problem, as plasma there is in a state referred to as 'collisionless' – the density and energy of particles and ions are such that individual collisions between them are extraordinarily rare. Therefore, the exchange of matter and energy between different plasma regions, as well as the acceleration of particles, must take place via mechanisms other than collisions. In fact, plasma has a very interesting feature that distinguishes it from an ordinary gas: while remaining neutral as a whole, local differences may develop in the distribution of its positive and negative charges. These inhomogeneities give rise to electric and magnetic fields and, in turn, the oscillations of such fields produce waves. Whereas particles in collisionless plasma hardly ever impact one another, they interact with these waves via the electromagnetic force and may gain or lose energy in the process.

In particular, theory suggests that electrons, which dominate the dynamics of plasma on small scales, are strongly affected by a special type of waves called lower hybrid drift waves. These waves are known to develop in plasma whenever its density and the strength of its magnetic field undergo an abrupt change. While these waves are well understood from a theoretical point of view, it has not been possible so far to fully characterise them experimentally, nor to probe their interaction with electrons. A new study based on data from ESA's Cluster mission has now shed light on the subject by measuring their wavelength and velocity in the magnetosphere.

"The small scales where lower hybrid drift waves are generated complicate the efforts to measure their properties," comments Cecilia Norgren, from the Swedish Institute of Space Physics, who is also a PhD student at Uppsala University, Sweden. Norgren is the lead author of the paper reporting on the study and published online on 31 July 2012 in Physical Review Letters. In the case of artificial plasma in the laboratory, measuring the wavelength and speed of these waves is practically impossible; the scales involved are of the order of a hundred microns or even less, and experimental probes are often of the same size, thus interfering with the measurement process. "Fortunately, the magnetic field strength in the Earth's magnetosphere is much weaker and lower hybrid drift waves arise on scales of a few tens of kilometres. This allows us to detect them by performing simultaneous measurements with multiple spacecraft, provided that the separation between them is also of the same scale," she adds.


Image above: The different plasma regions that make up Earth's magnetosphere. Credit: ESA (adapted from picture courtesy C. Russel).

 Norgren and her collaborators examined data collected with the Cluster spacecraft as they flew through the magnetotail, the long, cylindrical end of the magnetosphere that extends in the direction opposite the Sun. The magnetotail comprises the lobes, two plasma layers characterised by very low density and strong magnetic fields, and a denser layer between them – the plasma sheet – where the magnetic field is weaker than in the lobes. The plasma sheet is separated from the lobes by a very thin boundary. "Due to the drastically different properties of plasma on either side of narrow boundaries such as the one in the magnetotail, we expect these sites to host most of the energy exchanges that take place in a plasma," explains Mats André from the Swedish Institute of Space Physics, co-author of the paper and Norgren's PhD supervisor.

The team of scientists exploited a very favourable crossing of the Cluster spacecraft through this region. During several months in 2007, the four spacecraft were arranged in an unusual configuration, with two of them separated only by a few tens of km, and the other two at a much larger distance. "When the two nearby spacecraft were both located in the thin boundary on 31 August 2007, their separation was only 40 kilometres: an ideal setup to probe the behaviour of plasma on the scales where electrons become dominant and to search for lower hybrid drift waves," André adds.


Graphic above: Lower hybrid drift waves detected with two of Cluster's spacecraft. Image courtesy of Cecilia Norgren, Swedish Institute of Space Physics and Uppsala University, Sweden.

 Analysing the data, the team successfully detected such waves, measuring their wavelength, which is of the order of 60 kilometres, and propagation velocity, which is about 1000 kilometres per second. "The results represent the first detailed characterisation of lower hybrid drift waves in space and are in good agreement with theoretical expectations," notes Norgren. The velocity of the waves is of the same order as the typical velocity of ions in the magnetosphere plasma, as predicted by theory. "Furthermore, the electrostatic potential associated with the waves corresponds to about 10 per cent of the electron energy, suggesting that these waves may possess enough energy to have a strong impact on the dynamics of the electrons and to accelerate them," she adds.

The study by Norgren and her collaborators demonstrates that electrons do interact with lower hybrid drift waves and that this represents an efficient mechanism to transfer energy between different layers of plasma. Future studies will investigate this process in greater detail, trying to understand the role played by these waves in the context of magnetic reconnection.

"This study significantly improves our knowledge of the dynamics and energetics of plasma in the magnetosphere on the small scales governed by electrons," comments Matt Taylor, Cluster Project Scientist at ESA. Thus far, scientists had achieved a fairly good understanding of the magnetospheric plasma on very large scales, where it can be described in macroscopic terms, and on intermediate ones, dominated by ions, but the small-scale regime had remained less clear. "With this result, we have made a crucial step towards achieving an ever more detailed picture of our planet's magnetic environment," he concludes.

Notes for editors:

The study presented here is based on data gathered by two of the four Cluster spacecraft (C3 and C4) on 31 August 2007, as they were flying through the plasma sheet boundary layer in the tail of Earth's magnetosphere. During this event, the separation between the two spacecraft was small enough (about 40 km) to measure the wavelength of lower hybrid drift waves, a particular type of plasma waves that develop in the presence of sharp discontinuities in the plasma density and magnetic field strength. The observed wavelength of these waves is about 60 km, and they appear to propagate with a velocity of about 1000 km/s.

Cluster is a constellation of four spacecraft flying in formation around Earth. It is the first space mission able to study, in three dimensions, the natural physical processes occurring within and in the near vicinity of the Earth's magnetosphere. Launched in 2000, it is composed of four identical spacecraft orbiting the Earth in a pyramidal configuration, along a nominal polar orbit of 4 × 19.6 Earth radii (1 Earth radius = 6380 km). Cluster's payload consists of state-of-the-art plasma instrumentation to measure electric and magnetic fields over wide frequency ranges, and key physical parameters characterising electrons and ions from energies of near 0 eV to a few MeV. The science operations are coordinated by the Joint Science Operations Centre (JSOC) at the Rutherford Appleton Laboratory, United Kingdom, and implemented by ESA's European Space Operations Centre (ESOC), in Darmstadt, Germany.

Related publications:

C. Norgren, et al., "Lower hybrid drift waves: space observations", 2012, Phys. Rev. Lett., 109, 055001. DOI: 10.1103/PhysRevLett.109.055001.

For more information about CLUSTER missio, visit: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=8

Images (mentioned), Graphic (mentioned), Text, Credits: ESA.

Cheers, Orbiter.ch

A Blue Whirlpool in The River












ESO - European Southern Observatory logo.

1 August 2012

Tranquil galaxy home to violent events

VLT image of the spiral galaxy NGC 1187

A new image taken with ESO’s Very Large Telescope shows the galaxy NGC 1187. This impressive spiral lies about 60 million light-years away in the constellation of Eridanus (The River). NGC 1187 has hosted two supernova explosions during the last thirty years, the latest one in 2007. This picture of the galaxy is the most detailed ever taken.

The galaxy NGC 1187 [1] is seen almost face-on, which gives us a good view of its spiral structure. About half a dozen prominent spiral arms can be seen, each containing large amounts of gas and dust. The bluish features in the spiral arms indicate the presence of young stars born out of clouds of interstellar gas.

VLT image of the spiral galaxy NGC 1187 (annotated)

Looking towards the central regions, we see the bulge of the galaxy glowing yellow. This part of the galaxy is mostly made up of old stars, gas and dust. In the case of NGC 1187, rather than a round bulge, there is a subtle central bar structure. Such bar features are thought to act as mechanisms that channel gas from the spiral arms to the centre, enhancing star formation there.

Around the outside of the galaxy many much fainter and more distant galaxies can also be seen. Some even shine right through the disc of NGC 1187 itself. Their mostly reddish hues contrast with the pale blue star clusters of the much closer object.

The spiral galaxy NGC 1187 in the constellation of Eridanus

NGC 1187 looks tranquil and unchanging, but it has hosted two supernovae explosions since 1982. A supernova is a violent stellar explosion, resulting from the death of either a massive star or a white dwarf in a binary system [2]. Supernovae are amongst the most energetic events in the Universe and are so bright that they often briefly outshine an entire galaxy before fading from view over several weeks or months. During this short period a supernova can radiate as much energy as the Sun is expected to emit over its entire life span.

Wide-field view of the sky around the spiral galaxy NGC 1187

In October 1982, the first supernova seen in NGC 1187 — SN 1982R [3] was discovered at ESO’s La Silla Observatory and more recently, in 2007, the amateur astronomer Berto Monard in South Africa spotted another supernova in this galaxy — SN 2007Y. A team of astronomers subsequently performed a detailed study and monitored SN 2007Y for about a year using many different telescopes [4]. This new image of NGC 1187 was created from observations taken as part of this study and the supernova can be seen, long after the time of maximum brightness, near the bottom of the image.

video
Zooming in on the spiral galaxy NGC 1187

These data were acquired using the FORS1 instrument attached to the ESO’s Very Large Telescope at the Paranal Observatory in Chile.

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Panning across a new VLT image of the spiral galaxy NGC 1187

Notes:

[1] This galaxy was discovered in England by William Herschel in 1784.

[2] One class of supernova explosions occur at the end of a massive star’s lifetime — stars more massive than eight solar masses — when its nuclear fuel is exhausted and the star is not longer able to counteract gravitational collapse, producing a violent explosion. Alternatively, a supernova explosion can also occur in a binary star system, in which a carbon-oxygen white dwarf is pulling matter from a higher-mass companion star. If enough matter is transferred, the star will begin to collapse, producing the supernova explosion.

[3] The International Astronomical Union is responsible for naming supernovae after they are discovered. The name is formed by the year of discovery, followed by a one or two letter designation. The first 26 supernovae of the year get an upper case letter from A to Z. Subsequent supernovae are designated with two lower-case letters.

[4] Further information about SN 2007Y is available in a paper by Stritzinger et al.

More information:

The year 2012 marks the 50th anniversary of the founding of the European Southern Observatory (ESO). ESO 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 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 a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links:

    Photos of the VLT: http://www.eso.org/public/images/archive/category/paranal/

    Other images taken with the VLT: http://www.eso.org/public/images/archive/search/?adv=&facility=31

Images, Text, Credit: ESO / IAU and Sky & Telescope / Digitized Sky Survey 2. Acknowledgment: Davide De Martin / Videos: ESO/A. Fujii/Digitized Sky Survey 2. Acknowledgment: Davide De Martin. Music: Disasterpeace.

Greetings, Orbiter.ch

mardi 31 juillet 2012

Russian cargo spacecraft Progress M-15M undocked from the ISS










ROSCOSMOS - Russian Vehicles patch.

31/07/2012

In accordance with the schedule of the flight of the International Space Station today at 01:19:19 GMT Department made ​​cargo vehicle (THC), Progress M-15M from the docking module Pirs.

Progress M-15M undocked from ISS

After separation from the ISS during free flight in orbit working on the ship will conduct an experiment, Radar-Progress, which consists in the study of ground-based observations of the reflective characteristics of plasma irregularities in the ionosphere generated by the onboard engine THC Progress.

The purpose of the experiment is to determine the spatial and temporal dependence of the density, temperature, ionic composition of local inhomogeneities of the ionosphere, occurring as a result of on-board liquid-propellant rocket engines.

In the experiment, Radar-Progress is involved full-time equipment: propulsion THC Progress and VHF radio (Torah), as well as a set of ground-based radio observations.

video
The Russian spacecraft Progress undocked from the ISS and went to the free flight

He turned to the laboratory for physical experiments in the ionosphere. Especially for a three-week free flight on it a little bit of fuel left. After completion of the research mission of "Progress" in a designated flood area of ​​the Pacific Ocean, far from shipping routes. Vacant docking module on the station will take the following space vehicle that will carry into orbit food, water and scientific equipment. Its launch from Baikonur is scheduled for August 1.

Original text in Russian: http://www.federalspace.ru/main.php?id=2&nid=19372

Images, Video, Text, Credits: Press Service of the Russian Space Agency (Roscosmos PAO) / Roscosmos TV / 1 TV / NASA TV/ Translation: Orbiter.ch.

Cheers, Orbiter.ch