samedi 17 décembre 2011

1 Soyuz + 6 satellite payloads = Arianespace's latest launch success














ARIANESPACE - Flights VS02 Mission poster / ESA - Soyouz au CSG patch.

Dec. 17, 2011

Arianespace Flights VS02


Image above: Soyuz performs its second liftoff from the new French Guiana launch facility created for this medium-lift vehicle’s operations in service with Arianespace.

On Friday, December 16, 2011 at 11:03 pm local time, Arianespace successfully launched the second Soyuz rocket from the Guiana Space Center (CSG) in French Guiana, orbiting the Pleiades 1A.

video
 Arianespace Flights VS02

Designated Flight VS02 in Arianespace launcher family numbering system, tonight’s mission involved four burns of Soyuz’ Fregat upper stage, which enabled the six satellites to be released for operations at altitudes ranging from 610 km. to 700 km.   Using a new purpose-built payload dispenser developed for Arianespace’s Soyuz missions, the deployment sequence began with the release of Pléiades 1.  It was followed by the simultaneous separation of all four ELISA satellites, and the mission was completed with the deployment of SSOT, which occurred 3 hours, 26 minutes after liftoff.

The Soyuz lift performance was an estimated 2,190 kg., which includes approximately 1,400 kg. for the Pléiades 1, ELISA and SSOT satellites, along with the weight of its payload dispenser and integration hardware.  This was the 1,781st  flight of the Soyuz launcher family, which ushered in the space age and continues to demonstrate its reliability and robustness in both unmanned and manned missions.

Pléiades 1 satellite

Pléiades 1 weighed 970 kg. at launch and will provide military and civilian users with very high resolution optical satellite imagery from a 700-km. orbit, offering 50-cm. resolution imaging products at a coverage swath width of 20 km.  Built by prime contractor Astrium for the French CNES space agency, Pléiades 1 is a compact, hexagonal-shaped spacecraft optimized for operational agility and image location accuracy.

The Soyuz mission’s four ELISA micro-satellites are part of a joint demonstrator program involving the French DGA defense procurement organization and the country’s CNES space agency, with these spacecraft developed in a partnership of Astrium and Thales Airborne Systems.  Weighing 120 kg. each, they have an operational design life of more than three years.

OBC FM ELISA for military program

This latest success heralds Arianespace's upcoming offer of the most complete range of launch services in history, with the first Vega launch scheduled for early 2012.

Chile’s SSOT (Sistema satelital de Observación de la Tierra) is a dual-role military/civilian optical satellite that weighed 117 kg. at launch, and is designed for such missions as mapping, agricultural monitoring, and the management of natural resources, disasters and risks.   Built by Astrium for the Chilean armed forces, SSOT is based on the same CNES-conceived spacecraft platform as the ELISA satellites.

Second successful Soyuz launch from CSG

With Ariane 5, Soyuz and shortly the Vega light launcher, all launched from the Guiana Space Center, Arianespace is the only launch services company in the world capable of launching all types of payloads to all orbits, including communications, scientific and Earth observation satellites, constellations, cargo missions to the International Space Station and more.

Arianespace carried out a total of seven missions from the Guiana Space Center in 2011, all successful, including five Ariane 5 and two Soyuz launches.

More information about Arianespace, visit:  http://www.arianespace.com/index/index.asp

Images, Video, Text, Credits: ARIANESPACE / ESA / EADS-Astrium / Thales / Euronews.

Best regards, Orbiter.ch

vendredi 16 décembre 2011

Vega to fly ESA experimental reentry vehicle









ESA - IXV Intermediate eXperimental Vehicle.

16 December 2011

The launch of ESA’s IXV Intermediate eXperimental Vehicle on Europe’s new Vega rocket is now in detailed planning, a major step towards the craft’s flight in 2014.

Launched into a suborbital trajectory from Europe’s Spaceport in French Guiana, IXV will return to Earth as if from a low-orbit mission, to test and qualify new critical technologies for future reentry vehicles.

IXV Intermediate eXperimental Vehicle

It will attain an altitude of around 450 km, allowing it to reach a velocity of 7.5 km/s on entering the atmosphere. It will collect a large amount of data during its hypersonic and supersonic flight, while it is being controlled by thrusters and aerodynamic flaps.

IXV will then descend by parachute and land in the Pacific Ocean to await recovery and analysis. 

Intermediate eXperimental Vehicle (IXV)

ESA and the Arianespace launch provider signed a contract on 14 December to study the launch on Vega, as part of the VERTA – Vega Research and Technology Accompaniment – programme.

The rocket’s qualification flight planned for liftoff at the end of January will pave the way for the next five VERTA missions that will demonstrate the system’s flexibility.

Mr Le Gall, CEO of Arianespace and Mr Fabrizi, ESA Director of Launchers

At a planned rate of two launches per year, the programme will allow the smooth introduction of Vega for commercial exploitation.

Following development of critical technologies and completion of the design, the vehicle’s manufacturing, assembly, integration and qualification is now under way for a flight window between January and September 2014.

Procurement of the ground network has begun, including the mission control centre, ground station telemetry kits, transportable antennas and communication network.

About Vega

Vega is Europe’s new, small launcher. Its performance perfectly complements that of the heavy Ariane 5 and medium Soyuz rockets launched from French Guiana.

Vega

It is designed to cope with a wide range of missions and payload configurations in order to respond to different market opportunities and provide great flexibility. In particular, it offers configurations able to handle payloads ranging from a single satellite up to one main satellite plus six microsatellites.

Vega is compatible with payload masses ranging from 300 kg to 2500 kg, depending on the type and altitude of the orbit required by the customers. The benchmark is for 1500 kg into a 700 km-altitude polar orbit.

Related links:

Intermediate eXperimental Vehicle (IXV): http://www.esa.int/SPECIALS/Launchers_Technology/SEMDPQ2PGQD_0.html

Vega: http://www.esa.int/SPECIALS/Launchers_Access_to_Space/ASEKMU0TCNC_0.html

Images, Video, Text, Credits: ESA / J.Huart / S. Corvaja / AOES Medialab.

Greetings, Orbiter.ch

jeudi 15 décembre 2011

NASA's RXTE Detects 'Heartbeat' of Smallest Black Hole Candidate











NASA - Rossi X-ray Timing Explorer (RXTE) patch.

Dec. 15, 2011

video

This animation compares the X-ray 'heartbeats' of GRS 1915 and IGR J17091, two black holes that ingest gas from companion stars. GRS 1915 has nearly five times the mass of IGR J17091, which at three solar masses may be the smallest black hole known. A fly-through relates the heartbeats to hypothesized changes in the black hole's jet and disk. Credit: NASA / Goddard Space Flight Center / CI Lab.

An international team of astronomers has identified a candidate for the smallest-known black hole using data from NASA's Rossi X-ray Timing Explorer (RXTE). The evidence comes from a specific type of X-ray pattern, nicknamed a "heartbeat" because of its resemblance to an electrocardiogram. The pattern until now has been recorded in only one other black hole system.

Named IGR J17091-3624 after the astronomical coordinates of its sky position, the binary system combines a normal star with a black hole that may weigh less than three times the sun's mass. That is near the theoretical mass boundary where black holes become possible.

Gas from the normal star streams toward the black hole and forms a disk around it. Friction within the disk heats the gas to millions of degrees, which is hot enough to emit X-rays. Cyclical variations in the intensity of the X-rays observed reflect processes taking place within the gas disk. Scientists think that the most rapid changes occur near the black hole's event horizon, the point beyond which nothing, not even light, can escape.

Astronomers first became aware of the binary system during an outburst in 2003. Archival data from various space missions show it becomes active every few years. Its most recent outburst started in February and is ongoing. The system is located in the direction of the constellation Scorpius, but its distance is not well established. It could be as close as 16,000 light-years or more than 65,000 light-years away.

The record-holder for wide-ranging X-ray variability is another black hole binary system named GRS 1915+105. This system is unique in displaying more than a dozen highly structured patterns, typically lasting between seconds and hours.

"We think that most of these patterns represent cycles of accumulation and ejection in an unstable disk, and we now see seven of them in IGR J17091," said Tomaso Belloni at Brera Observatory in Merate, Italy. "Identifying these signatures in a second black hole system is very exciting."

In GRS 1915, strong magnetic fields near the black hole's event horizon eject some of the gas into dual, oppositely directed jets that blast outward at about 98 percent the speed of light. The peak of its heartbeat emission corresponds to the emergence of the jet.

RXTE description

Changes in the X-ray spectrum observed by RXTE during each beat reveal that the innermost region of the disk emits enough radiation to push back the gas, creating a strong outward wind that stops the inward flow, briefly starving the black hole and shutting down the jet. This corresponds to the faintest emission. Eventually, the inner disk gets so bright and hot it essentially disintegrates and plunges toward the black hole, re-establishing the jet and beginning the cycle anew. This entire process happens in as little as 40 seconds.

While there is no direct evidence IGR J17091 possesses a particle jet, its heartbeat signature suggests that similar processes are at work. Researchers say that this system's heartbeat emission can be 20 times fainter than GRS 1915 and can cycle some eight times faster, in as little as five seconds.

Astronomers estimate that GRS 1915 is about 14 times the sun's mass, placing it among the most-massive-known black holes that have formed because of the collapse of a single star. The research team analyzed six months of RXTE observations to compare the two systems, concluding that IGR J17091 must possess a minuscule black hole.

"Just as the heart rate of a mouse is faster than an elephant's, the heartbeat signals from these black holes scale according to their masses," said Diego Altamirano, an astrophysicist at the University of Amsterdam in The Netherlands and lead author of a paper describing the findings in the Nov. 4 issue of The Astrophysical Journal Letters.

Rossi X-ray Timing Explorer (RXTE)

The researchers say this analysis is just the start of a larger program to compare both of these black holes in detail using data from RXTE, NASA's Swift satellite and the European XMM-Newton observatory.

"Until this study, GRS 1915 was essentially a one-off, and there's only so much we can understand from a single example," said Tod Strohmayer, the project scientist for RXTE at NASA's Goddard Space Flight Center in Greenbelt, Md. "Now, with a second system exhibiting similar types of variability, we really can begin to test how well we understand what happens at the brink of a black hole."

Launched in late 1995, RXTE is second only to Hubble as the longest serving of NASA's operating astrophysics missions. RXTE provides a unique observing window into the extreme environments of neutron stars and black holes.

Related links

Dutch press release
http://www.astronomie.nl/nieuws/2362/astronomen_observeren_de_hartslag_van_een_piepklein_zwart_gat.html

Italian press release
http://www.media.inaf.it/2011/12/12/batticuore-buco-nero/

GRS 1915+105: Taking the Pulse of a Black Hole System
http://chandra.harvard.edu/photo/2011/g1915/

RXTE Homes in on a Black Hole's Jets
http://www.nasa.gov/topics/universe/features/black-hole-jets.html

Images, Video, Text, Credit: NASA / Goddard Space Flight Center / Francis Reddy / CI Lab.

Greetings, Orbiter.ch

Young star rebels against its parent cloud












ESA - Hubble Space Telescope logo.

15 December 2011

Hubble’s Wide Field Camera 3 has captured this image of a giant cloud of hydrogen gas illuminated by a bright young star. The image shows how violent the end stages of the star-formation process can be, with the young object shaking up its stellar nursery.

video
Animation of S 106

Despite the celestial colours of this picture, there is nothing peaceful about star forming region Sh 2-106, or S106 for short. A devilish young star, named S106 IR, lies in it and ejects material at high speed, which disrupts the gas and dust around it. The star has a mass about 15 times that of the Sun and is in the final stages of its formation. It will soon quieten down by entering the main sequence, the adult stage of stellar life.

Hubble view of star-forming region S106

For now, S106 IR remains embedded in its parent cloud, but it is rebelling against it. The material spewing off the star not only gives the cloud its hourglass shape but also makes the hydrogen gas in it very hot and turbulent. The resulting intricate patterns are clearly visible in this Hubble image. 

The young star also heats up the surrounding gas, making it reach temperatures of 10 000 degrees Celsius. The star’s radiation ionises the hydrogen lobes, making them glow. The light from this glowing gas is coloured blue in this image.

Hubble / Subaru composite of star-forming region S 106

Separating these regions of glowing gas is a cooler, thick lane of dust, appearing red in the image. This dark material almost completely hides the ionising star from view, but the young object can still be seen peeking through the widest part of the dust lane.

S106 was the 106th object to be catalogued by the astronomer Steward Sharpless in the 1950s. It is a few thousand light-years distant in the direction of Cygnus (The Swan). The cloud itself is relatively small by the standards of star-forming regions, around 2 light-years along its longest axis. This is about half the distance between the Sun and Proxima Centauri, our nearest stellar neighbour.

Ground-based view of the area around star-forming region S 106

This composite picture was obtained with the Wide Field Camera 3 on the NASA / ESA Hubble Space Telescope. It results from the combination of two images taken in infrared light and one which is tuned to a specific wavelength of visible light emitted by excited hydrogen gas, known as H-alpha. This choice of wavelengths is ideal for targetting star-forming regions. The H-alpha filter isolates the light emitted from hydrogen in gas clouds while the infrared light can shine through the dust that often obscures these regions.

video
Zooming in on S 106

Videos:

Hubblecast 51: Star-forming region S 106: http://www.spacetelescope.org/videos/heic1118a/

Pan over S 106: http://www.spacetelescope.org/videos/heic1118d/

Artist’s impression of S 106: http://www.spacetelescope.org/videos/heic1118e/

Related Links:

Hubble overview: http://www.esa.int/science/hubble

Hubble factsheet: http://www.esa.int/esaSC/SEMB5E1A6BD_index_0.html

Hubblecast at the Hubble ESA Information Centre: http://www.spacetelescope.org/videos/archive/topic/hubblecast//

Hubble in depth: http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=47209

Where is Hubble now?

Track Hubble: http://www.esa.int/esaSC/SEMK8E2PL7F_index_0.html

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

Images, Text, Credits: NASA / ESA / the Hubble Heritage Team (STScI / AURA) / NAOJ / Digitized Sky Survey 2 (Acknowledgement: Davide De Martin) / Videos: NASA, ESA, and G. Bacon, T. Borders, L. Frattare, Z. Levay, and F. Summers (Viz 3D team, STScI) / Digitized Sky Survey 2, NAOJ and Nick Risinger. Music: John Dyson (from the album Moonwind).

Greetings, Orbiter.ch

A Galaxy Blooming with New Stars












ESO - European Southern Observatory logo.

15 December 2011

VLT Survey Telescope snaps wide-field view of NGC 253

Wide-field view of NGC 253 from the VLT Survey Telescope

The VLT Survey Telescope (VST) has captured the beauty of the nearby spiral galaxy NGC 253. The new portrait is probably the most detailed wide-field view of this object and its surroundings ever taken. It demonstrates that the VST, the newest telescope at ESO's Paranal Observatory, provides broad views of the sky while also offering impressive image sharpness.

NGC 253 gleams about eleven and a half million light-years away in the southern constellation of Sculptor. It is often just called the Sculptor Galaxy, although other descriptive names include the Silver Coin or Silver Dollar Galaxy. It is easy to get a good look at NGC 253 through binoculars as it is one of the brightest galaxies in the sky after the Milky Way's closest, big galactic neighbour, the Andromeda Galaxy.

The galaxy NGC 253 in the constellation of Sculptor

Astronomers have noted the widespread active star formation in NGC 253 and labelled it a "starburst" galaxy [1]. The many bright clumps dotting the galaxy are stellar nurseries where hot young stars have just ignited. The radiation streaming from these giant blue-white babies makes the surrounding hydrogen gas clouds glow brightly (green in this image).

This nearby spiral galaxy was discovered by the German–British astronomer Caroline Herschel, the sister of the famed astronomer William Herschel, as she searched for comets in 1783. The Herschels would have been delighted by the crisp, richly detailed view of NGC 253 that the VST can provide.

Wide-field view of the sky around NGC 253

This latest image of NGC 253 was taken during VST’s science verification phase — when the telescope’s scientific performance is assessed before it enters operations. The VST data are being combined with infrared images from VISTA (eso0949) to identify the younger generations of stars in NGC 253. This picture is more than 12 000 pixels across and the superb sky conditions at ESO’s Paranal Observatory, combined with the fine telescope optics, result in sharp star images over the entire image.

The VST is a 2.6-metre wide-field survey telescope with a one-degree field of view — twice as broad as the full Moon [2]. The VST programme is a joint venture between the INAF–Osservatorio Astronomico di Capodimonte, Naples, Italy and ESO (eso1119). The 268-megapixel camera OmegaCAM at its heart is designed to map the sky both quickly and with very fine image quality. VST is the largest telescope in the world designed to exclusively survey the sky in visible light, complementing ESO's VISTA infrared survey telescope, also located at Paranal.


video
Zooming in on NGC 253

Zooming into this new picture not only allows a very detailed inspection of the star-forming spiral arms of the galaxy to be made, but also reveals a very rich tapestry of much more distant galaxies far beyond NGC 253.

Notes:

[1] Further details about NGC 253 have been revealed by ESO's Very Large Telescope (VLT) along with the NASA/ESA Hubble Space Telescope. These instruments showed in 2009 that, at its centre, NGC 253 harbours  a supermassive black hole with very similar properties to those of  the black hole lurking in the Milky Way's core (see ESO Press Release eso0902).

[2] The image presented here has been cropped and is slightly smaller than the full VST field of view.

More information:

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 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:

ESO Press Release:

eso0949: http://www.eso.org/public/news/eso0949/

eso1119: http://www.eso.org/public/news/eso1119/

eso0902: http://www.eso.org/public/news/eso0902/

Photos of the VST: http://www.eso.org/public/images/archive/search/?category=1111&adv=&description=VST

VST public web pages: http://www.eso.org/public/teles-instr/surveytelescopes/vst.html

Images, Text, Credits: ESO / INAF-VST / Acknowledgement: A. Grado / L. Limatola / INAF-Capodimonte Observatory / IAU and Sky & Telescope / Digitized Sky Survey 2. Acknowledgment: Davide De Martin / Video: ESO / INAF-VST, Nick Risinger (skysurvey.org) and Digitized Sky Survey 2. Acknowledgement: A. Grado / L. Limatola / INAF-Capodimonte Observatory / Music: John Dyson (from the album Moonwind).

Best regards, Orbiter.ch

Portraits of Moons Captured by Cassini












NASA - Cassini - Huygens Mission to Saturn & Titan patch.

Dec. 15, 2011


Image above: NASA's Cassini spacecraft obtained this unprocessed image on Dec. 12, 2011. Image credit: NASA / JPL-Caltech / Space Science Institute

NASA’s Cassini spacecraft successfully completed its closest-ever pass over Saturn’s moon Dione on Monday, Dec. 12, slaloming its way through the Saturn system on its way to tomorrow’s close flyby of Titan. Cassini is expected to glide about 2,200 miles (3,600 kilometers) over the Titan surface on Dec. 13.

In the selection of the raw images obtained during the Cassini Dione flyby, Dione is sometimes joined by other moons. Mimas appears just beyond the dark side of Dione in one view. In another view, Epimetheus and Pandora appear together, along with Saturn’s rings.


Image above: NASA's Cassini spacecraft obtained this unprocessed image on Dec. 12, 2011. Image credit: NASA / JPL-Caltech / Space Science Institute

This Dione encounter was intended primarily for Cassini's composite infrared spectrometer and radio science subsystem. However, the imaging team did capture views of the distinctive, wispy fractures on the side of Dione that always trails in its orbit around Saturn. It also obtained images of a ridge called Janiculum Dorsa on the hemisphere of Dione that always leads in its orbit around Saturn. While other flybys produced more detailed views of the surface, the best resolved images from this flyby have scales ranging from about 1,100 feet (350 meters) to about 1,600 feet (500 meters) per pixel. Janiculum Dorsa will be imaged by Cassini at higher resolution in May 2012.


Image above: NASA's Cassini spacecraft obtained this unprocessed image on Dec. 12, 2011. Image credit: NASA / JPL-Caltech / Space Science Institute

All of Cassini’s raw images can be seen at http://saturn.jpl.nasa.gov/photos/raw/ .

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena manages the mission for the agency's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations team is based at the Space Science Institute in Boulder, Colo. JPL is a division of Caltech.

More Cassini information is available at http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov

Images (mentioned), Text, Credit: NASA / JPL / Jia-Rui Cook.

Greetings, Orbiter.ch

mercredi 14 décembre 2011

A Black Hole's Dinner is Fast Approaching












ESO - European Southern Observatory logo.

14 December 2011

VLT spots cloud being disrupted by black hole

 Simulation of gas cloud approaching the black hole at the centre of the Milky Way

Astronomers using ESO’s Very Large Telescope have discovered a gas cloud with several times the mass of the Earth accelerating fast towards the black hole at the centre of the Milky Way. This is the first time ever that the approach of such a doomed cloud to a supermassive black hole has been observed. The results will be published in the 5 January 2012 issue of the journal Nature.

During a 20-year programme using ESO telescopes to monitor the movement of stars around the supermassive black hole at the centre of our galaxy (eso0846) [1], a team of astronomers led by Reinhard Genzel at the Max-Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany, has discovered a unique new object fast approaching the black hole.

Simulation of gas cloud approaching the black hole at the centre of the Milky Way

Over the last seven years, the speed of this object has nearly doubled, reaching more than 8 million km/h. It is on a very elongated orbit [2] and in mid-2013 it will pass at a distance of only about 40 billion kilometres from the event horizon of the black hole, a distance of about 36 light-hours [3]. This is an extremely close encounter with a supermassive black hole in astronomical terms.

This object is much cooler than the surrounding stars (only about 280 degrees Celsius), and is composed mostly of hydrogen and helium. It is a dusty, ionised gas cloud with a mass roughly three times that of the Earth. The cloud is glowing under the strong ultraviolet radiation from the hot stars around it in the crowded heart of the Milky Way.

The centre of the Milky Way showing a newly discovered and rapidly moving cloud

The current density of the cloud is much higher than the hot gas surrounding the black hole. But as the cloud gets ever closer to the hungry beast, increasing external pressure will compress the cloud. At the same time the huge gravitational pull from the black hole, which has a mass four million times that of the Sun, will continue to accelerate the inward motion and stretch the cloud out along its orbit.

“The idea of an astronaut close to a black hole being stretched out to resemble spaghetti is familiar from science fiction. But we can now see this happening for real to the newly discovered cloud. It is not going to survive the experience,” explains Stefan Gillessen (MPE) the lead author of the paper.

video
Simulation of gas cloud approaching the black hole at the centre of the Milky Way

The cloud’s edges are already starting to shred and disrupt and it is expected to break up completely over the next few years [4]. The astronomers can already see clear signs of increasing disruption of the cloud over the period between 2008 and 2011.

video
A gas cloud falling towards the supermassive black hole at the centre of the Milky Way

The material is also expected to get much hotter as it nears the black hole in 2013 and it will probably start to give off X-rays. There is currently little material close to the black hole so the newly-arrived meal will be the dominant fuel for the black hole over the next few years.

video
Zooming in on the centre of the Milky Way

One explanation for the formation of the cloud is that its material may have come from nearby young massive stars that are rapidly losing mass due to strong stellar winds. Such stars literally blow their gas away. Colliding stellar winds from a known double star in orbit around the central black hole may have led to the formation of the cloud.

video
Animation of objects orbiting the centre of the Milky Way

“The next two years will be very interesting and should provide us with extremely valuable information on the behaviour of matter around such remarkable massive objects,” concludes Reinhard Genzel.

Notes:

[1] The black hole at the centre of the Milky Way is formally known as Sgr A* (pronounced Sagittarius A star). It is the closest supermassive black hole known by far and hence is the best place to study black holes in detail.

[2] The observations were made using the NACO infrared adaptive optics camera and the SINFONI infrared spectrograph, both attached to the ESO Very Large Telescope in Chile. The centre of the Milky Way lies behind thick dust clouds that scatter and absorb visible light and must be observed at infrared wavelengths where the clouds are more transparent.

[3] A light-hour is the distance that light travels in one hour. It is a little more than the distance from the Sun to the planet Jupiter in the Solar System. For comparison the distance between the Sun and the nearest star is more than four light-years. The cloud will pass at less than ten times the distance from the Sun to Neptune from the black hole

[4] This effect well known from the physics of fluids and can be seen when for example pouring syrup in a glass of water. The flow of syrup downwards through the water will be disrupted and the droplet will break apart — effectively diluting the syrup in the water.

More information:

This research was presented in a paper “A gas cloud on its way towards the super-massive black hole in the Galactic Centre”, by S. Gillessen et al., to appear in the 5 January 2012 issue of the journal Nature.

The team is composed of S. Gillessen (Max-Planck-Institut für extraterrestrische Physik [MPE], Germany), R. Genzel (MPE; Department of Physics, University of California [UC], USA), T. Fritz (MPE, Germany), E. Quataert (Department of Astronomy, UC, USA), C. Alig (Universitätssternwarte der Ludwig-Maximilians-Universität [LMU], Germany), A. Burkert (MPE; LMU), J. Cuadra (Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Chile), F. Eisenhauer (MPE), O. Pfuhl (MPE), K. Dodds-Eden (MPE), C. Gammie (Center for Theoretical Astrophysics, University of Illinois, USA), T. Ott (MPE).

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 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”.

Videos:

ESOcast 39: A Black Hole’s Dinner is Fast Approaching: http://www.eso.org/public/videos/eso1151a/

Video News Release: A Black Hole’s Dinner is Fast Approaching – B-roll: http://www.eso.org/public/videos/eso1151g/

Video News Release 36: A Black Hole’s Dinner is Fast Approaching (eso1151b): http://www.eso.org/public/videos/eso1151b/

Links:

    Research paper in Nature: http://www.eso.org/public/archives/releases/sciencepapers/eso1151/eso1151.pdf

    MPE web page on the Galactic Centre: http://www.mpe.mpg.de/ir/GC/index.php

    Images of Paranal: http://www.eso.org/public/images/archive/category/paranal/

Images, Videos, Text, Credits: ESO / MPE / Marc Schartmann / Nick Risinger (skysurvey.org) / VISTA / J. Emerson / Digitized Sky Survey 2 / L. Calçada.

Best regards, Orbiter.ch

NASA Mars-Bound Rover Begins Research in Space










NASA - Mars Science Laboratory (MSL) patch.

Dec. 14, 2011

NASA's car-sized Curiosity rover has begun monitoring space radiation during its 8-month trip from Earth to Mars. The research will aid in planning for future human missions to the Red Planet.

Curiosity launched on Nov. 26 from Cape Canaveral, Fla., aboard the Mars Science Laboratory (MSL). The rover carries an instrument called the Radiation Assessment Detector (RAD) that monitors high-energy atomic and subatomic particles from the sun, distant supernovas and other sources.

These particles constitute radiation that could be harmful to any microbes or astronauts in space or on Mars. The rover also will monitor radiation on the surface of Mars after its August 2012 landing.

"RAD is serving as a proxy for an astronaut inside a spacecraft on the way to Mars,” said Don Hassler, RAD's principal investigator from the Southwest Research Institute in Boulder, Colo.”The instrument is deep inside the spacecraft, the way an astronaut would be. Understanding the effects of the spacecraft on the radiation field will be valuable in designing craft for astronauts to travel to Mars."

Previous monitoring of energetic-particle radiation in space has used instruments at or near the surface of various spacecraft. The RAD instrument is on the rover inside the spacecraft and shielded by other components of MSL, including the aeroshell that will protect the rover during descent through the upper atmosphere of Mars.

Spacecraft structures, while providing shielding, also can contribute to secondary particles generated when high-energy particles strike the spacecraft. In some circumstances, secondary particles could be more hazardous than primary ones.

video
MSL Spacecraft Mars Bound

These first measurements mark the start of the science return from a mission that will use 10 instruments on Curiosity to assess whether Mars' Gale Crater could be or has been favorable for microbial life.

"While Curiosity will not look for signs of life on Mars, what it might find could be a game- changer about the origin and evolution of life on Earth and elsewhere in the universe,” said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. “One thing is certain: the rover's discoveries will provide critical data that will impact human and robotic planning and research for decades.”

As of noon EST on Dec. 14, the spacecraft will have traveled 31.9 million miles (51.3 million kilometers) of its 352-million-mile (567-million-kilometer) flight to Mars. The first trajectory correction maneuver during the trip is being planned for mid-January.

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Mars Science Laboratory Curiosity Rover Animation

Southwest Research Institute, together with Christian Albrechts University in Kiel, Germany, built RAD with funding from the Human Exploration and Operations Mission Directorate, NASA Headquarters, Washington, and Germany's national aerospace research center, Deutsches Zentrum für Luft- und Raumfahrt.

The mission is managed by NASA's Jet Propulsion Laboratory (JPL) for the agency's Science Mission Directorate in Washington. The mission's rover was designed, developed and assembled at JPL.

Information about the mission is available at: http://www.nasa.gov/msl

You can follow the mission on Facebook and Twitter at: http://www.facebook.com/marscuriosity or http://www.twitter.com/marscuriosity

Videos, Text, Credit: NASA / NASA TV / JPL.

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SMOS detects freezing soil as winter takes grip









ESA - SMOS Mission logo.

14 December 2011

ESA’s SMOS satellite is designed to observe soil moisture and ocean salinity, but this innovative mission is showing that it can also offer new insight into Earth’s carbon and methane cycles by mapping soil as it freezes and thaws.

The launch of the Soil Moisture and Ocean Salinity (SMOS) mission in November 2009 opened up a new era of monitoring Earth using a new remote-sensing technique.

Frozen soil

The satellite is capturing images of ‘brightness temperature’. These images correspond to microwave radiation emitted from Earth’s surface and can be related to soil moisture and ocean salinity.

Variability in soil moisture and ocean salinity is a consequence of the continuous exchange of water between the oceans, the atmosphere and the land – Earth’s water cycle. 

While SMOS provides essential information for understanding the water cycle, weather and climate system, scientists from the Finnish Meteorological Institute have recently developed a method of using the data to detect and map frozen soils.

SMOS in orbit

Not only can the extent be mapped, but also the depth of the frozen layer can be inferred.

The animation shown above compares data from 26 November 2010 and 26 November 2011. Last year large parts of northern Finland were frozen to depths exceeding 30 cm. This year, however, autumn has been much milder and only a small area had frozen by 26 November.

Interestingly, as the next maps show, the advance of winter this year can be closely monitored.

Frozen soil, 26 November

The image on the above shows the state of the soil on 26 November and one below shows how much more soil has frozen just four days later.

As soil freezes every year, it stores large amounts of carbon and methane, which are released back into the atmosphere when it thaws in the spring.

Moreover, there is great concern that rising global temperatures will cause permanently frozen soil, permafrost, in high latitudes to thaw – releasing massive volumes of carbon and methane and adding further to the greenhouse effect.

Dr Kimmo Rautiainen from the Finnish Meteorological Institute (FMI) said, “The state of the soil has always been of particular interest in northern latitudes.

“Detecting frozen soils and the depth to which they are frozen from space has been an unresolved scientific problem.

“However, we are now confident that the novel observations provided by the SMOS mission will help advance our understanding of processes occurring in cold regions.”

Using SMOS data, the scientists have developed a method of inferring the depth of the frozen layer.

Frozen soil, 30 November

During the freezing process, brightness temperatures increase until the top 50 cm of the soil is frozen. Over winter the readings remain stable, even under the presence of deep snow. Thawing in spring then leads to a decrease in brightness temperature.

The SMOS data have been validated by observations taken from a ground-based radiometer at FMI’s Arctic Research Centre in Sodankylä, northern Finland.

Sodankylä site

Through a study being carried out within ESA’s Support to Science Element, the methods of detecting frozen soil will be refined further.

It is envisaged that similar data will be produced and released for use in applications such as numerical weather prediction and hydrology.

Related links:

Finnish Meteorological Institute: http://en.ilmatieteenlaitos.fi/

CESBIO–SMOS blog: http://www.cesbio.ups-tlse.fr/SMOS_blog/

SMOS in depth: http://www.esa.int/esaLP/LPsmos.html

SMOS: http://www.esa.int/SPECIALS/smos/index.html

Images, Animation, Text, Credits: ESA / Finnish Meteorological Institute / AOES Medialab.

Greetings, Orbiter.ch

A Galaxy Cluster Gets Sloshed











NASA - Chandra X-ray Observatory patch.

Dec. 14, 2011


Like wine in a glass, vast clouds of hot gas are sloshing back and forth in Abell 2052, a galaxy cluster located about 480 million light years from Earth. X-ray data (blue) from NASA's Chandra X-ray Observatory shows the hot gas in this dynamic system, and optical data (gold) from the Very Large Telescope shows the galaxies. The hot, X-ray bright gas has an average temperature of about 30 million degrees.

A huge spiral structure in the hot gas -- spanning almost a million light years -- is seen around the outside of the image, surrounding a giant elliptical galaxy at the center. This spiral was created when a small cluster of galaxies smashed into a larger one that surrounds the central elliptical galaxy.

The smaller cluster passed the cluster core, the direction of motion of the cluster gas reversed and it traveled back towards the cluster center. The cluster gas moved through the center again and "sloshed" back and forth, similar to wine sloshing in a glass that was jerked sideways. The sloshing gas ended up in a spiral pattern because the collision between the two clusters was off-center.

The Chandra data show clear bubbles evacuated by material blasted away from the black hole, which are surrounded by dense, bright, cool rims. As with the sloshing, this activity helps prevent cooling of the gas in the cluster's core, setting limits on the growth of the giant elliptical galaxy and its supermassive black hole.

Image, Text, Credit: X-ray: NASA / CXC / BU / L.Blanton; Optical: ESO / VLT .

Cheers, Orbiter.ch

Galileo in tune: first navigation signal transmitted to Earth












ESA - GALILEO logo.

14 December 2011

Europe’s Galileo system has passed its latest milestone, transmitting its very first test navigation signal back to Earth.

The first two Galileo satellites were launched into orbit on 21 October. Since then their systems have been activated and the satellites placed into their final orbits, positioned so that their navigation antennas are aligned with the world they are designed to serve.

Last weekend marked the first orbital transmission from one of these navigation antennas. The stage was set, the singer in place and an audience – in the shape of engineers on the ground – was waiting eagerly.

Galileo In-Orbit Validation satellite

The question was would the singer make music, and if so, would it be in tune? 

The turn of Galileo’s main ‘L-band’ (1200-1600 MHz) antenna came on the early morning of Saturday 10 December. A test signal was transmitted by the first Galileo satellite in the ‘E1’ band, which will be used for Galileo’s Open Service once the system begins operating in 2014.

First Galileo test navigation signal

To prepare for the test, the payload power amplifiers were switched on and ‘outgassed’ – warmed up to release vapours that might otherwise interfere with operations – before transmission began.

A 20 m-diameter L-band antenna stood ready and waiting at Redu. The antenna is an essential ingredient of Galileo testing, able to assess the shape and quality of the navigation signals, even with the target satellite being 23 222 km up in orbit.

The signal power and shape was well within specifications. The shape is especially important because its modulation is carefully designed to enable interoperability with the ‘L1’ band of US GPS navigation satellites: Galileo and GPS can indeed work together as planned.

20-m diameter antenna at Redu

The test campaign is concentrating on the first satellite for the reminder of the year, with the focus moving to the second Galileo satellite from the start of 2012. The plan is to complete In-Orbit Testing by next spring.

The next pair of Galileo In-Orbit Validation satellites will also be launched next year, to form the operational nucleus of the full Galileo constellation. Meanwhile the next batch of Galileo satellites are currently being manufactured for launch in 2014.

About Galileo

Galileo is an initiative of the European Commission and ESA to provide Europe with an independent global satellite navigation system.

Galileo team at Redu

The Galileo satnav system combines the best atomic clock ever flown for navigation – accurate to one second in three million years – with a powerful transmitter to broadcast precise navigation data worldwide.

Related links:

Navigation: http://www.esa.int/esaNA/index.html

Galileo: http://www.esa.int/esaNA/galileo.html

Redu Centre: http://www.esa.int/SPECIALS/About_ESA/SEM4UQJ4LOG_0.html

Images, Text, Credits: ESA / Thibault Denis.

Greetings, Orbiter.ch

mardi 13 décembre 2011

NASA's Dawn Spirals Down to Lowest Orbit












NASA - Dawn Mission patch.

Dec. 13, 2011


This artist's concept shows NASA's Dawn spacecraft orbiting the giant asteroid Vesta. Image credit: NASA / JPL-Caltech.

NASA's Dawn spacecraft successfully maneuvered into its closest orbit around the giant asteroid Vesta today, beginning a new phase of science observations. The spacecraft is now circling Vesta at an altitude averaging about 130 miles (210 kilometers) in the phase of the mission known as low altitude mapping orbit.

"Dawn has performed some complicated and beautiful choreography in order to reach this lowest orbit," said Marc Rayman, Dawn chief engineer and mission manager based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We are in an excellent position to learn much more about the secrets of Vesta's surface and interior."

Launched in 2007, Dawn has been in orbit around Vesta, the second most massive object in the asteroid belt between Mars and Jupiter, since July 15. The team plans to acquire data in the low orbit for at least 10 weeks.

Dawn's framing camera and visible and infrared mapping spectrometer instruments will image portions of the surface at greater resolution than obtained at higher altitudes. But the primary goal of the low orbit is to collect data for the gamma ray and neutron detector (GRaND) and the gravity experiment. GRaND will be looking for the by-products of cosmic rays reflected off Vesta to reveal the identities of many kinds of atoms in the surface of Vesta. The instrument is most effective at this low altitude.


This image of the giant asteroid Vesta was obtained by NASA's Dawn spacecraft in the evening Nov. 27 PST (early morning Nov. 28, UTC), as it was spiraling down from its high altitude mapping orbit to low altitude mapping orbit. Image credit: NASA / JPL-Caltech.

Close proximity to Vesta also enables ultrasensitive measurements of its gravitational field. These measurements will tell scientists about the way masses are arranged in the giant asteroid's interior.

"Dawn's visit to Vesta has been eye-opening so far, showing us troughs and peaks that telescopes only hinted at," said Christopher Russell, Dawn's principal investigator, based at UCLA. "It whets the appetite for a day when human explorers can see the wonders of asteroids for themselves."

After the science collection is complete at the low altitude mapping orbit, Dawn will spiral out and conduct another science campaign at the high altitude mapping orbit altitude (420 miles, or 680 kilometers), when the sun will have risen higher in the northern regions. Dawn plans to leave Vesta in July 2012 and arrive at its second destination, the dwarf planet Ceres, in February 2015.

Dawn's mission to Vesta and Ceres is managed by JPL for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corp. in Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are international partners on the mission team.

For more information about the Dawn mission, visit: http://www.nasa.gov/dawn and http://dawn.jpl.nasa.gov .

To follow the mission on Twitter, visit: http://www.twitter.com/NASA_Dawn .

Images, Text, Credit: NASA / JPL-Caltech / Jia-Rui Cook.

Cheers, Orbiter.ch

NASA's Fermi Shows That Tycho's Star Shines in Gamma Rays











NASA - Fermi Gamma-ray Space Telescope logo.

Dec. 13, 2011


Image above: Gamma-rays detected by Fermi's LAT show that the remnant of Tycho's supernova shines in the highest-energy form of light. This portrait of the shattered star includes gamma rays (magenta), X-rays (yellow, green, and blue), infrared (red) and optical data. (Credit: Gamma ray, NASA / DOE / Fermi LAT Collaboration; X-ray, NASA / CXC / SAO; Infrared, NASA / JPL-Caltech; Optical, MPIA, Calar Alto, O. Krause et al. and DSS).

In early November 1572, observers on Earth witnessed the appearance of a "new star" in the constellation Cassiopeia, an event now recognized as the brightest naked-eye supernova in more than 400 years. It's often called "Tycho's supernova" after the great Danish astronomer Tycho Brahe, who gained renown for his extensive study of the object. Now, years of data collected by NASA's Fermi Gamma-Ray Space Telescope reveal that the shattered star's remains shine in high-energy gamma rays.

The detection gives astronomers another clue in understanding the origin of cosmic rays, subatomic particles -- mainly protons -- that move through space at nearly the speed of light. Exactly where and how these particles attain such incredible energies has been a long-standing mystery because charged particles speeding through the galaxy are easily deflected by interstellar magnetic fields. This makes it impossible to track cosmic rays back to their sources.

"Fortunately, high-energy gamma rays are produced when cosmic rays strike interstellar gas and starlight. These gamma rays come to Fermi straight from their sources," said Francesco Giordano at the University of Bari and the National Institute of Nuclear Physics in Italy. He is the lead author of a paper describing the findings in the Dec. 7 edition of The Astrophysical Journal Letters.

Better understanding the origins of cosmic rays is one of Fermi's key goals. Its Large Area Telescope (LAT) scans the entire sky every three hours, gradually building up an ever-deeper view of the gamma-ray sky. Because gamma rays are the most energetic and penetrating form of light, they serve as signposts for the particle acceleration that gives rise to cosmic rays.

"This detection gives us another piece of evidence supporting the notion that supernova remnants can accelerate cosmic rays," said co-author Stefan Funk, an astrophysicist at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), jointly located at SLAC National Accelerator Laboratory and Stanford University, Calif.

In 1949, physicist Enrico Fermi -- the satellite's namesake -- suggested that the highest-energy cosmic rays were accelerated in the magnetic fields of interstellar gas clouds. In the decades that followed, astronomers showed that supernova remnants may be the galaxy's best candidate sites for this process.

video

Video above: The gamma-ray emission from Tycho's supernova remnant can be explained by pion production. A proton traveling close to the speed of light strikes a slower-moving proton. Their interaction creates an unstable particle -- a pion -- with only 14 percent of the proton's mass. In 10 millionths of a billionth of a second, the pion decays into a pair of gamma rays. (Credit: NASA's Goddard Space Flight Center).

When a star explodes, it is transformed into a supernova remnant, a rapidly expanding shell of hot gas bounded by the blast's shockwave. Scientists expect that magnetic fields on either side of the shock front can trap particles between them in what amounts to a subatomic pingpong game.

"A supernova remnant's magnetic fields are very weak relative to Earth's, but they extend across a vast region, ultimately spanning thousands of light-years. They have a major influence on the course of charged particles," said co-author Melitta Naumann-Godo at Paris Diderot University and the Atomic Energy Commission in Saclay, France, who led the study with Giordano.

As they shuttle back and forth across the supernova shock, the charged particles gain energy with each traverse. Eventually they break out of their magnetic confinement, escaping the supernova remnant and freely roaming the galaxy.

The LAT's ongoing sky survey provides additional evidence favoring this scenario. Many younger remnants, like Tycho's, tend to produce more high-energy gamma rays than older remnants. "The gamma-ray energies reflect the energies of the accelerated particles that produce them, and we expect more cosmic rays to be accelerated to higher energies in younger objects because the shockwaves and their tangled magnetic fields are stronger," Funk added. By contrast, older remnants with weaker shockwaves cannot retain the highest-energy particles, and the LAT does not detect gamma rays with corresponding energies.

The supernova of 1572 was one of the great watersheds in the history of astronomy. The star blazed forth at a time when the starry sky was regarded as a fixed and unchanging part of the universe. Tycho's candid account of his own discovery of the strange star gives a sense of how radical an event it was.


Image above: Tycho's map shows the supernova's position (largest symbol, at top) relative to the stars that form the constellation Cassiopeia. (Credit: Gerstein Science Information Centre, Univ. of Toronto).

The supernova first appeared around Nov. 6, but poor weather kept it from Tycho until Nov. 11, when he noticed it during a walk before dinner. "When I had satisfied myself that no star of that kind had ever shone forth before, I was led into such perplexity by the unbelievability of the thing that I began to doubt the faith of my own eyes, and so, turning to the servants who were accompanying me, I asked them whether they too could see a certain extremely bright star…. They immediately replied with one voice that they saw it completely and that it was extremely bright," he recalled.

The supernova remained visible for 15 months and exhibited no movement in the heavens, indicating that it was located far beyond the sun, moon and planets. Modern astronomers estimate that the remnant lies between 9,000 and 11,000 light-years away.

After more than two and a half years of scanning the sky, LAT data clearly show that an unresolved region of GeV (billion electron volt) gamma-ray emission is associated with the remnant of Tycho's supernova. (For comparison, the energy of visible light is between about 2 and 3 electron volts.)

Keith Bechtol, a KIPAC graduate student who is also based at SLAC, was one of the first researchers to notice the potential link. "We knew that Tycho's supernova remnant could be an important find for Fermi because this object has been so extensively studied in other parts of the electromagnetic spectrum. We thought it might be one of our best opportunities to identify a spectral signature indicating the presence of cosmic-ray protons," he said.

The science team's model of the emission is based on LAT observations, along with higher-energy TeV (trillion electron volt) gamma rays mapped by ground-based facilities and radio and X-ray data. The researchers conclude that a process called pion production best explains the emission. First, a proton traveling close to the speed of light strikes a slower-moving proton. This interaction creates an unstable particle -- a pion -- with only 14 percent of the proton's mass. In just 10 millionths of a billionth of a second, the pion decays into a pair of gamma rays.

If this interpretation is correct, then somewhere within the remnant, protons are being accelerated to near the speed of light, and then interacting with slower particles to produce gamma rays, the most extreme form of light. With such unbelievable goings-on in what's left of his "unbelievable" star, it's easy to imagine that Tycho Brahe himself might be pleased.

Related Links

    - NASA's Fermi Closes on Source of Cosmic Rays: http://www.nasa.gov/mission_pages/GLAST/news/cosmic-rays-source.html

    - NASA'S Chandra Finds New Evidence on Origin of Supernovas: http://chandra.harvard.edu/photo/2011/tycho2/

    - A New View of Tycho's Supernova Remnant: http://chandra.harvard.edu/photo/2005/tycho/

    - Reproduction of Tycho's book on the 1572 supernova: http://www.archive.org/details/operumprimitiasd00brahuoft

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

Greetings, Orbiter.ch