samedi 4 mai 2013

A year ago, a collision was averted between Fermi Gamma-ray Observatory and a oldest soviet spy satellite out of service










Satellite Collision.

May 4, 2013

 Predicted collision on March 29, 2012

NASA scientists provided details this week of how they dodged a 1.5-ton bullet in space last year when they had to fire the thruster engines on the Fermi Gamma-ray Telescope to nudge it out of the way and narrowly avoid a collision with a 26-year-old defunct Soviet-era satellite.

Cosmos 1805 satellite

NASA said it learned of the possible collision on March 29, 2012 when it received an automatically generated report indicating that the $690 million Fermi Space Telescope and the Soviet Cosmos 1805 satellite would pass within 700 feet (213 meters) of each other in a week.

Fermi Gamma-ray Observatory spacecraft

Fermi mission scientists monitored the impending close call and then determined that the two spacecraft would actually pass within 30 milliseconds of each other.

Images, Text, Credits: Voice of Russia / RIA / NASA / Youtube.

Greetings, Orbiter.ch

Sun Emits Mid-Level Flare












NASA - Solar Dynamics Observatory (SDO) patch.

May 4, 2013

The sun emitted a mid-level solar flare, peaking at 1:32 pm EDT on May 3, 2013. Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel. This disrupts the radio signals for as long as the flare is ongoing, and the radio blackout for this flare has already subsided.


Image above: NASA's Solar Dynamics Observatory captured this image of an M5.7-class flare on May 3, 2013, at 1:30 p.m. EDT. This image shows light in the 131-angstrom wavelength, a wavelength of light that can show material at the very hot temperatures of a solar flare and that is typically colorized in teal. Credit: NASA/SDO/AIA.

This flare is classified as an M5.7-class flare. M-class flares are the weakest flares that can still cause some space weather effects near Earth. Increased numbers of flares are quite common at the moment, as the sun's normal 11-year activity cycle is ramping up toward solar maximum, which is expected in late 2013.


Image above: A burst of solar material leaps off the left side of the sun in what’s known as a prominence eruption. This image combines three images from NASA's Solar Dynamics Observatory captured on May 3, 2013, at 1:45 pm EDT, just as an M-class solar flare from the same region was subsiding. The images include light from the 131-, 171- and 304-angstrom wavelengths. Credit: NASA/SDO/AIA.

Updates will be provided as they are available on the flare and whether there was an associated coronal mass ejection, another solar phenomenon that can send solar particles into space and affect electronic systems in satellites and on Earth.

What is a solar flare?

For answers to these and other space weather questions, please visit the Spaceweather Frequently Asked Questions page: http://www.nasa.gov/mission_pages/sunearth/spaceweather/index.html

Related Links:

View Past Solar Activity: http://www.nasa.gov/mission_pages/sunearth/multimedia/Solar-Events.html

Images (mentioned), Text, Credit: NASA's Goddard Space Flight Center / Karen C. Fox.

Cheers, Orbiter.ch

NASA's Fermi, Swift See 'Shockingly Bright' Burst













NASA - Fermi Gamma-ray Space Telescope logo / NASA - Swift Mission patch.

May 4, 2013

A record-setting blast of gamma rays from a dying star in a distant galaxy has wowed astronomers around the world. The eruption, which is classified as a gamma-ray burst, or GRB, and designated GRB 130427A, produced the highest-energy light ever detected from such an event.

"We have waited a long time for a gamma-ray burst this shockingly, eye-wateringly bright," said Julie McEnery, project scientist for the Fermi Gamma-ray Space Telescope at NASA's Goddard Space Flight Center in Greenbelt, Md. "The GRB lasted so long that a record number of telescopes on the ground were able to catch it while space-based observations were still ongoing."


Animation above: The maps in this animation show how the sky looks at gamma-ray energies above 100 million electron volts (MeV) with a view centered on the north galactic pole. The first frame shows the sky during a three-hour interval prior to GRB 130427A. The second frame shows a three-hour interval starting 2.5 hours before the burst, and ending 30 minutes into the event. The Fermi team chose this interval to demonstrate how bright the burst was relative to the rest of the gamma-ray sky. This burst was bright enough that Fermi autonomously left its normal surveying mode to give the LAT instrument a better view, so the three-hour exposure following the burst does not cover the whole sky in the usual way. Credit: NASA/DOE/Fermi LAT Collaboration.

Just after 3:47 a.m. EDT on Saturday, April 27, Fermi's Gamma-ray Burst Monitor (GBM) triggered on an eruption of high-energy light in the constellation Leo. The burst occurred as NASA's Swift satellite was slewing between targets, which delayed its Burst Alert Telescope's detection by less than a minute.

Fermi's Large Area Telescope (LAT) recorded one gamma ray with an energy of at least 94 billion electron volts (GeV), or some 35 billion times the energy of visible light, and about three times greater than the LAT's previous record. The GeV emission from the burst lasted for hours, and it remained detectable by the LAT for the better part of a day, setting a new record for the longest gamma-ray emission from a GRB.


Animation above: This animation shows a more detailed Fermi LAT view of GRB 130427A. The sequence shows high-energy (100 Mev to 100 GeV) gamma rays from a 20-degree-wide region of the sky starting three minutes before the burst to 14 hours after. Following an initial one-second spike, the LAT emission remained relatively quiet for the next 15 seconds while Fermi's GBM instrument showed bright, variable lower-energy emission. Then the burst re-brightened in the LAT over the next few minutes and remained bright for nearly half a day. Credit: NASA/DOE/Fermi LAT Collaboration.

The burst subsequently was detected in optical, infrared and radio wavelengths by ground-based observatories, based on the rapid accurate position from Swift. Astronomers quickly learned that the GRB was located about 3.6 billion light-years away, which for these events is relatively close.

Gamma-ray bursts are the universe's most luminous explosions. Astronomers think most occur when massive stars run out of nuclear fuel and collapse under their own weight. As the core collapses into a black hole, jets of material shoot outward at nearly the speed of light.

The jets bore all the way through the collapsing star and continue into space, where they interact with gas previously shed by the star and generate bright afterglows that fade with time.


Image above: Swift's X-Ray Telescope took this 0.1-second exposure of GRB 130427A at 3:50 a.m. EDT on April 27, just moments after Swift and Fermi triggered on the outburst. The image is 6.5 arcminutes across. Credit: NASA/Swift/Stefan Immler.

If the GRB is near enough, astronomers usually discover a supernova at the site a week or so after the outburst.

"This GRB is in the closest 5 percent of bursts, so the big push now is to find an emerging supernova, which accompanies nearly all long GRBs at this distance," said Goddard's Neil Gehrels, principal investigator for Swift.

Ground-based observatories are monitoring the location of GRB 130427A and expect to find an underlying supernova by midmonth.

Related Links:

Download additional graphics from NASA Goddard's Scientific Visualization Studio: http://svs.gsfc.nasa.gov/vis/a010000/a011200/a011261/

Archive of GRB notices from the Gamma-ray Coordination Network: http://gcn.gsfc.nasa.gov/gcn3_archive.html

"NASA's Fermi Telescope Sees Most Extreme Gamma-ray Blast Yet"
(02.19.09): http://www.nasa.gov/mission_pages/GLAST/news/high_grb.html

NASA's Fermi Gamma-ray Space Telescope: http://www.nasa.gov/fermi

NASA's Swift mission: http://www.nasa.gov/swift

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

Greetings, Orbiter.ch

Hubble Sees the Remains of a Star Gone Supernova












NASA - Hubble Space Telescope patch.

May 4, 2013


These delicate wisps of gas make up an object known as SNR B0519-69.0, or SNR 0519 for short. The thin, blood-red shells are actually the remnants from when an unstable progenitor star exploded violently as a supernova around 600 years ago. There are several types of supernovae, but for SNR 0519 the star that exploded is known to have been a white dwarf star — a Sun-like star in the final stages of its life.

SNR 0519 is located over 150 000 light-years from Earth in the southern constellation of Dorado (The Dolphinfish), a constellation that also contains most of our neighboring galaxy the Large Magellanic Cloud (LMC). Because of this, this region of the sky is full of intriguing and beautiful deep sky objects.

The LMC orbits the Milky Way galaxy as a satellite and is the fourth largest in our group of galaxies, the Local Group. SNR 0519 is not alone in the LMC; the NASA/ESA Hubble Space Telescope also came across a similar bauble a few years ago in SNR B0509-67.5, a supernova of the same type as SNR 0519 with a strikingly similar appearance.

For more information about Hubble visit: http://hubblesite.org/ and http://www.spacetelescope.org/

Image credits: ESA / Hubble & NASA. Acknowledgement: Claude Cornen / Text, Credits: European Space Agency  /NASA Hubble.

Best regards, Orbiter.ch

vendredi 3 mai 2013

Galileo and GPS ‘synchronise watches’: new time offset helps working together












ESA - GALILEO Mission logo.

3 May 2013

Ensuring the early interoperability of Europe’s satellite navigation with GPS, the four Galileo satellites have begun broadcasting the ‘offset’ between the parallel navigation systems’ timings, accurate to a few billionths of a second.

With satellite navigation based around the highly accurate measurement of signal travel times, both Galileo and GPS have their own internal reference time systems used to synchronise all system clocks and signals.

Galileo

The problem is these time systems are not quite identical, with Galileo System Time being around 50 nanoseconds or less apart from GPS time.

“A nanosecond is only a billionth of a second, corresponding to the time light takes to travel 30 cm,” explains Jörg Hahn, Galileo System Engineering Manager.

“But this soon adds up, and for anyone attempting to use the two systems together might find this ‘offset’ accounting for up to 15 m of error, causing an unacceptable contribution to user performance.”

Instead, this time offset needs to be known or estimated by the receiver itself.

Galileo to GPS Time Offset, GGTO

“The dissemination of the GPS to Galileo offset can help in constrained environments such as city centres, where only a few satellites are visible in the sky,” adds Jörg.

“The receiver can then take this offset and align all the observations to a single time scale, reducing the computational burden on the receiver since the amount of unknowns are decreased.”

Accordingly, disseminating the offset will help enable the user receiver market to start making use of Galileo at this early stage, with only four satellites yet in orbit.

Formally known as the GPS to Galileo time offset, GGTO, the accuracy of the offset is being benchmarked at five nanoseconds or less.

A tale of two times

Galileo runs on Galileo System Time, GST, which is generated on the ground at the Galileo Control Centre in Fucino, Italy, by the Precise Timing Facility, based on averages of different atomic clocks. GPS time is computed by the GPS control segment.

These two internal times are derived independently on one another but are kept close to the world’s reference time, UTC, with the offset between the two being precisely calculated on a continuous basis by the PTF and the resulting GGTO distributed through Galileo’s navigation message.

Fucino

GPS and Galileo share some frequencies (L1/E1 at 1575.420 MHz and L5/E5a at 1176.450 MHz) with a view to interoperability, and disseminating the GGTO makes using the two systems together more straightforward still.

“GGTO determination methods and interface design were agreed on a preliminary basis between the Galileo Project and the US Naval Observatory back in 2003, through a GGTO subgroup of the US and EU Working Group A on Compatibility and Interoperability,” Jörg concludes. “We’ve worked together closely since then to make the GGTO a reality.”

About satellite navigation: http://www.esa.int/Our_Activities/Navigation/About_satellite_navigation2

Europe's satellite navigation services: http://www.esa.int/Our_Activities/Navigation/Europe_s_satellite_navigation_services

Images, Text, Credits: ESA / P. Carril / Telespazio.

Cheers, Orbiter.ch

SolarImpulse ACROSS AMERICA 2013

SolarImpulse Across America 2013 patch.

May 3, 2013

Mission Kick-Off

Are you ready to be part of the adventure? Because the historic solar-powered crossing of the United States is about to begin!

SolarImpulse over San Francisco

Bertrand will pilot this first leg of the 2013 Across America mission while André will undertake the last one, Washington D.C. to New York City. With Bertrand at the commands, HB-SIA will take off from Moffett Airfield around 6 am PDT (UTC-7) on Friday May 3rd and land at Sky Harbor International Airport in Phoenix (AZ) sometime after midnight PDT (UTC-7).

The solar airplane will fly southbound, west of Yosemite National Park, above Fresno and Bakersfield. He will then veer westward toward Palmdale and Barstow, over the Mojave National Preserve in the direction of Phoenix.

The kick-off of the mission will also act as the launching of a global initiative - “Clean Generation” - to promote clean technologies. Pilots André and Bertrand will carry a USB key with them in the cockpit throughout the mission with all the names of Solar Impulse supporters. The goal is to encourage this global movement of change-makers to grow, raising awareness along the way about what can be done with innovative technologies for sustainable economic growth.

video
Across America 2013: Golden Gate Flight

Don't forget to watch the Solar Impulse TV that brings you all the most exciting news about mission flights LIVE directly on our homepage. Also, if you want to stay informed throughout the crossing and have your name virtually travel from California to New York, sign up today to become a Supporter!

As with all mission flights, pilots André and Bertrand will be tweeting from the ground and from the air: follow them directly on their Twitter accounts @ André and Bertrand or simply Solar Impulse.

Final itinerary revealed!

Solar Impulse’s 2013 Across America itinerary is now official!

    Moffett Airfield (Mountain View, CA)
    Sky Harbor International Airport (Phoenix, AZ)
    Dallas/Fort Worth International Airport (Dallas, TX)
    Lambert-St. Louis International Airport (St. Louis, MO)
    Dulles International Airport (Washington D.C.)
    John F. Kennedy International Airport (New York City)

Across America 2013 itinerary

We’ve all been touched by the incredible welcome the Federal Aviation Administration (FAA) and different airport authorities have given us in the United States. In fact, before we started organizing the mission, we were afraid we wouldn’t find airports ready to welcome our unique aircraft. To our surprise, it was exactly the opposite! This has obliged us to better evaluate our needs and decide accordingly.

The most difficult choice was our third stopover, which was torn between St. Louis (MO), Atlanta (GA) and Nashville (TN). For various reasons, including one very historical one, St. Louis was elected as the official third stopover. The Spirit of St. Louis, piloted by Charles Lindbergh, was the first aircraft to successfully undertake the crossing of the Atlantic, New York to Paris, in 1927. The 3,600 mile flight (5’800 km) started from Roosevelt Field on New York’s Long Island to Le Bourget Field in Paris. Although the aircraft was built in San Diego, it got its name in honor of the St. Louis Raquette Club - who financed the construction of the aircraft - and because it was Lindbergh’s residence at the time. 

It looks like the next possible date for the kick-off of the 2013 Across America mission could be this Friday, May 3rd! Weather conditions permitting, the flight would take off from Moffett Airfield to Sky Harbor International Airport in Phoenix (AZ). It will be an early departure, most likely before 6 am local time (UTC-7) with a landing after midnight local Phoenix time (UTC-7).

Join us in this incredible adventure! Sign-up today to ensure you get the latest news about the flights directly in your inbox!

And don’t forget, all Solar Impulse flights are broadcasted live on our website!: http://solarimpulse.com/

Images, Video, Text, Credit: SolarImpulse.

Greetings, Orbiter.ch

jeudi 2 mai 2013

Cluster Hears the Heartbeat of Magnetic Reconnection












ESA - Cluster II Mission patch.

02 May 2013

For the first time, scientists have resolved the detailed structure of the core region where magnetic reconnection takes place in the magnetosphere of Earth using unprecedented wave measurements. The study, based on data from ESA's Cluster mission, has mapped different types of electrostatic waves in this region. The waves trace populations of plasma particles that are involved in the different stages of a magnetic reconnection event.

In most cosmic environments, matter is not made up of neutral atoms and molecules, but rather of electrically charged particles and ions. This ionised state of matter, called plasma, is permeated by electric and magnetic fields caused by local inhomogeneities in the distribution of particles and ions. These fields in turn influence the dynamics of the plasma on larger scales, so the distribution of the particles, ions, and fields changes constantly.

video

Video above: Magnetic reconnection in Earth's magnetosphere. Credit: ESA/ATG medialab.

Magnetic reconnection is ubiquitous in the Universe. The phenomenon, which occurs in plasma, is triggered by microscopic processes and causes macroscopic effects: magnetic field lines from different domains collide and later assume a different configuration. Magnetic reconnection produces rapid and global changes to the arrangement of a magnetic environment – for example, the magnetosphere of Earth. This process is an efficient mechanism to convert energy stored in the magnetic field to kinetic energy.

Waves play an important role in the transfer of mass and energy across different plasma layers. Various types of waves develop during magnetic reconnection and tracing these waves through in situ measurements in Earth's magnetosphere is a unique way to investigate the reconnection process. Scientists have now used data from ESA's Cluster mission to characterise electrostatic waves in the tail of the magnetosphere and to 'see' into the heart of a magnetic reconnection region.

"Most of the action during a magnetic reconnection event takes place at the thin boundaries that separate different layers of plasma. For the first time, we were able to see through this thin boundary and identify the different types of waves that arise there," says Henrik Viberg from the Swedish Institute of Space Physics in Uppsala, Sweden. Viberg is a PhD student at Uppsala University and lead author of the paper, published in Geophysical Research Letters, reporting the new findings based on data from Cluster.

The magnetic reconnection region in the tail of Earth's magnetosphere. Credit: ESA/ATG medialab

Magnetic reconnection starts with two colliding flows of plasma whose magnetic fields are aligned along opposite directions: when pushed together, these create a thin sheet of current. As plasma keeps flowing towards this sheet from both sides, particles are accelerated and eventually released via two jets. This creates an X-shaped transition region, with a 'separatrix' region that divides the inflowing plasma from the outflows of highly energetic particles.

Viberg and his colleagues searched through the vast data archive of the Cluster mission for an event during which the spacecraft crossed the separatrix region during magnetic reconnection, and during which they were collecting data with the Wide Band Data (WBD) instrument. By making high-resolution measurements of the electric and magnetic fields, WBD allows scientists to probe the structure of the plasma through waves, rather than particles. Although they found only one suitable event in the archive, the spacecraft had crossed the transition between inflow and outflow regions several times during this event, providing enough statistics for a robust investigation.

"Since electrostatic waves are a local phenomenon and don't propagate over long distances, they allow us to look very closely into the magnetic reconnection region," explains Yuri Khotyaintsev, Viberg's supervisor at the Swedish Institute of Space Physics.

"The Cluster spacecraft detected waves only in the separatrix region – not in the inflowing or outflowing plasma – confirming our earlier suspicions. But there's more, because we have also resolved, for the first time, the structure of this region, as the spacecraft saw different types of electrostatic waves while flying across the separatrix."


Illustration above: Different types of waves in the magnetic reconnection region: Electron-Cyclotron waves are represented in cyan, Langmuir waves in blue and Electrostatic Solitary Waves in white. Credit: ESA/ATG medialab.

Close to the boundary between separatrix and inflow regions, the scientists identified two types of waves: one type with high frequencies, the Langmuir waves, and another with low frequencies, known as Electron-Cyclotron waves. Deeper into the separatrix region, towards the outflowing plasma, they detected Electrostatic Solitary Waves – single-pulsed waves that span a very broad frequency range.

"If we drew a parallel with sound waves, we could associate Langmuir waves with the high-pitched sound produced by a violin, while Electron-Cyclotron waves would be closer to the lower-pitched music from a cello," comments Khotyaintsev. "The Electrostatic Solitary Waves would be more like the sound of maracas, consisting of short, individual pulses based on more than one pitch."

This study provides the first detailed mapping of the types of waves found throughout the magnetic reconnection region and the first detection of Electron-Cyclotron waves in such a region. Resolving the structure of the separatrix region allows scientists to investigate the mechanisms underlying magnetic reconnection. Since different types of waves are produced by particles with different properties, the scientists analysed the correlation between the populations of particles detected in conjunction with the various types of waves.

ESA's Cluster II spacecrafts constellation. Image credit: ESA

"We find high-energy electrons along with Langmuir waves: this is consistent with what we believe to be the origin of these waves, which can be generated by beams of high-energy electrons emerging from the X-shaped reconnection region. We detected Electron-Cyclotron waves in the same region, but we were not able to identify the mechanism that generates them," says Viberg.

"Closer to the outflowing jets, the beam of high-energy electrons becomes more intense and flows of low-energy electrons streaming against the beam are also found here. This counter-streaming distribution is known to give rise to instabilities and, eventually, to Electrostatic Solitary Waves – which are exactly the waves we find in these regions," he adds.

In future studies, the scientists plan to investigate if and how these electrostatic waves, which are confined to the magnetic reconnection region, might produce electromagnetic waves, able to propagate over much longer distances. This would allow a comparison between Earth's magnetic environment and the many different sites where magnetic reconnection occurs, ranging from the corona of the Sun, to the accretion discs around forming stars, to plasma created in the laboratory.

"Working at the peak of its instrumental capabilities, Cluster has mapped what goes on at the core of the magnetic reconnection region. This provides an important insight into this fundamental process that takes place in plasma all across the Universe," concludes Matt Taylor, Cluster Project Scientist at ESA.

Notes for editors:

The study presented here is based on data gathered by three of the four Cluster spacecraft (C1, C3 and C4) on 10 September 2001 as they crossed a magnetic reconnection region in the magnetotail of Earth's magnetic environment.

Cluster is a constellation of four spacecraft flying in formation around Earth. It is the first space mission to be able to study, in three dimensions, the natural physical processes occurring within and near 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 a wide frequency range, and key physical parameters characterizing electrons and ions from energies of nearly 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:

H. Viberg, et al., "Mapping High-Frequency Waves in the Reconnection Diffusion Region", 2013, Geophysical Research Letters, Vol. 40, Pages 1–6. DOI: 10.1002/grl.50227

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

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

Greetings, Orbiter.ch

An Anarchic Region of Star Formation












ESO - European Southern Observatory logo.

2 May 2013

 The star formation region NGC 6559

The Danish 1.54-metre telescope located at ESO’s La Silla Observatory in Chile has captured a striking image of NGC 6559, an object that showcases the anarchy that reigns when stars form inside an interstellar cloud.

NGC 6559 is a cloud of gas and dust located at a distance of about 5000 light-years from Earth, in the constellation of Sagittarius (The Archer). The glowing region is a relatively small object, just a few light-years across, in contrast to the one hundred light-years and more spanned by its famous neighbour, the Lagoon Nebula (Messier 8, eso0936). Although it is usually overlooked in favour of its distinguished companion, NGC 6559 has the leading role in this new picture.

The gas in the clouds of NGC 6559, mainly hydrogen, is the raw material for star formation. When a region inside this nebula gathers enough matter, it starts to collapse under its own gravity. The centre of the cloud grows ever denser and hotter, until thermonuclear fusion begins and a star is born. The hydrogen atoms combine to form helium atoms, releasing energy that makes the star shine.

The star formation region NGC 6559 in the constellation of Sagittarius

These brilliant hot young stars born out of the cloud energise the hydrogen gas still present around them in the nebula [1]. The gas then re-emits this energy, producing the glowing threadlike red cloud seen near the centre of the image. This object is known as an emission nebula.

But NGC 6559 is not just made out of hydrogen gas. It also contains solid particles of dust, made of heavier elements, such as carbon, iron or silicon. The bluish patch next to the red emission nebula shows the light from the recently formed stars being scattered — reflected in many different directions — by the microscopic particles in the nebula. Known to astronomers as a reflection nebula, this type of object usually appears blue because the scattering is more efficient for these shorter wavelengths of light [2].

video
Zooming in on the star formation region NGC 6559

In regions where it is very dense, the dust completely blocks the light behind it, as is the case for the dark isolated patches and sinuous lanes to the bottom left-hand side and right-hand side of the image. To look through the clouds at what lies behind, astronomers would need to observe the nebula using longer wavelengths that would not be absorbed.

The Milky Way fills the background of the image with countless yellowish older stars. Some of them appear fainter and redder because of the dust in NGC 6559.

video
Panning across the star formation region NGC 6559

This eye-catching image of star formation was captured by the Danish Faint Object Spectrograph and Camera (DFOSC) on the 1.54-metre Danish Telescope at La Silla in Chile. This national telescope has been in use at La Silla since 1979 and was recently refurbished to turn it into a remote-controlled state-of-the-art telescope.

Notes:

[1] These young stars are usually of spectral type O and B, with temperatures between 10 000 and 60 000 K, which radiate huge amounts of high energy ultraviolet light that ionises the hydrogen atoms.

[2] Rayleigh scattering, named after the British physicist Lord Rayleigh, happens when light is scattered off particles of material that are much smaller than the wavelength of the light. It is much more effective for short wavelengths of light, that is, wavelengths corresponding to the blue end of the visible spectrum, so the result is a bluish diffuse light. This is the same mechanism that explains the blue colour of the daytime cloud-free sky.

More information:

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

Links:

Photos of the Danish telescope: http://www.eso.org/public/images/archive/search/?adv=&subject_name=1.54

Photos taken with the Danish telescope: http://www.eso.org/public/images/archive/search/?adv=&facility=18

ESO press releases with results from the Danish telescope: http://www.eso.org/public/news/archive/search/?adv=&facility=18

Images, Text, Credits: ESO, IAU and Sky & Telescope / Videos: ESO/Nick Risinger (skysurvey.org)/S. Guisard. Music: movetwo.

Greetings, Orbiter.ch

Landslides and lava flows at Olympus Mons on Mars












ESA - Mars Express Mission patch.

2 May 2013

 Sulci Gordii

Giant landslides, lava flows and tectonic forces are behind this dynamic scene captured recently by ESA’s Mars Express of a region scarred by the Solar System’s largest volcano, Olympus Mons.

The image was taken on 23 January by the spacecraft’s high-resolution stereo camera, and focuses on a region known as Sulci Gordii, which lies about 200 km east of Olympus Mons.

Sulci Gordii is an ‘aureole’ deposit – from the Latin for ‘circle of light’ – and is one of many that form a broken ring around the giant volcano, as hinted at in the context map.

Sulci Gordii in context

The aureoles tell the story of the catastrophic collapse of the lower flanks of Olympus Mons in its distant past. Today, it stands with steep cliff edges that rise 2 km above the surrounding plains.

The collapse was brought about by weakening in the rocks supporting the volcanic edifice, perhaps influenced by subsurface water. During the collapse, rocky debris slid down and out over hundreds of kilometres of the surrounding volcanic plains, giving rise to the rough-textured aureole seen today.

Inside Sulci Gordii

Similar avalanches of debris are also seen surrounding some volcanoes on Earth, including Mauna Loa in Hawaii, which, like Olympus Mons, is a smooth-sided ‘shield’ volcano built up from successive lava flows.

The smooth plains surrounding Sulci Gordii suggest that the massive landslide was later partially buried by lava flows. Indeed, faint outlines of ancient lava flows can be seen by zooming into the upper centre-left portion of the lead high-resolution image.

Sulci Gordii close-up

The characteristic corrugated appearance of the ‘sulci’ – a geological term used to describe roughly parallel hills and valleys on Mars – likely resulted during the landslide as material slid away from the volcano and became compressed or pulled apart as it travelled across the surface. Over time, erosion of weaker material between the peaks accentuated this effect.

The corrugated effect is best seen in the close-up perspective views. Zooming in on these images reveals that the hills and ridges are also covered by fine wind-blown dust, and that many small-scale landslides have occurred down the sides of the valleys between them.

Similarly, on close inspection of the smooth plains, subtle ripples in the martian dust blanket can be seen. Here, thin undulating dunes have been whipped into shape by the prevailing wind.

Channels and fractures in Sulci Gordii

Numerous sinuous channels and jagged fracture networks also crisscross the scene, in particular at the southern (left) end of the main image and in close-up in the perspective view above. The channels range in length from around 50 km to 300 km and were probably widened by short-lived lava flows, or perhaps even by water.

An impressive sight on the left side of the perspective view is a sinuous channel that is suddenly truncated by a tectonic fault. Another channel running across the centre foreground clearly has a complex fracturing history.

Sulci Gordii topography

In rougher terrain towards the south (top centre-right of the main image), tectonic forces have torn apart the martian crust, most clearly visible in the colour-coded topography map.

By studying complex regions like this – and by comparing them to similar examples here on Earth – planetary scientists learn more about the geological processes that dominated ancient Mars, when it was an active planet.

Sulci Gordii in 3D

Just as on Earth, the scene at Sulci Gordii tells us that volcanoes can suffer dramatic collapses that transport vast quantities of material across hundreds of kilometres, where it is subsequently sculpted by wind, water and tectonic forces.

Related links:

Mars Express mission facts: http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Mars_Express_mission_facts

Mars Express instruments: http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Mars_Express_instruments

The mission: http://www.esa.int/Our_Activities/Space_Science/Mars_Express/The_mission

The spacecraft: http://www.esa.int/Our_Activities/Space_Science/Mars_Express/The_spacecraft

Images, Text, Credits: ESA/DLR/FU Berlin (G. Neukum).

Best regards, Orbiter.ch

mercredi 1 mai 2013

Circular Coronal Mass Ejection












NASA - Solar Dynamics Observatory (SDO) patch.

May 1, 2013

video
 Circular Coronal Mass Ejection

A coronal mass ejection (CME) erupted from just around the edge of the sun on May 1, 2013, in a gigantic rolling wave. CMEs can shoot over a billion tons of particles into space at over a million miles per hour. This CME occurred on the sun’s limb and is not headed toward Earth. The video, taken in extreme ultraviolet light by NASA’s Solar Dynamics Observatory (SDO), covers about two and a half hours. Credit: NASA/SDO.

What is a solar prominence?

A solar prominence (also known as a filament when viewed against the solar disk) is a large, bright feature extending outward from the Sun's surface. Prominences are anchored to the Sun's surface in the photosphere, and extend outwards into the Sun's hot outer atmosphere, called the corona. A prominence forms over timescales of about a day, and stable prominences may persist in the corona for several months, looping hundreds of thousands of miles into space. Scientists are still researching how and why prominences are formed.

The red-glowing looped material is plasma, a hot gas comprised of electrically charged hydrogen and helium. The prominence plasma flows along a tangled and twisted structure of magnetic fields generated by the sun’s internal dynamo. An erupting prominence occurs when such a structure becomes unstable and bursts outward, releasing the plasma.


Image above: A solar eruptive prominence as seen in extreme UV light on March 30, 2010 with Earth superimposed for a sense of scale. Credit: NASA/SDO.

What is a coronal mass ejection or CME?

The outer solar atmosphere, the corona, is structured by strong magnetic fields. Where these fields are closed, often above sunspot groups, the confined solar atmosphere can suddenly and violently release bubbles of gas and magnetic fields called coronal mass ejections. A large CME can contain a billion tons of matter that can be accelerated to several million miles per hour in a spectacular explosion. Solar material streams out through the interplanetary medium, impacting any planet or spacecraft in its path. CMEs are sometimes associated with flares but can occur independently.

For answers to these and other space weather questions, please visit the Spaceweather Frequently Asked Questions page: http://www.nasa.gov/mission_pages/sunearth/spaceweather/index.html

Images, Video, Text, Credits: NASA / SDO.

NASA Spacecraft Will Visit Asteroid with New Name












NASA - OSIRIS-Rex Mission patch.

May 1, 2013

An asteroid that will be explored by a NASA spacecraft has a new name, thanks to a third-grade student in North Carolina.

OSIRIS-REx asteroid samples return mission

NASA's Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer (OSIRIS-REx) spacecraft will visit the asteroid now called Bennu, named after an important ancient Egyptian avian deity. OSIRIS-Rex is scheduled to launch in 2016, rendezvous with Bennu in 2018 and return a sample of the asteroid to Earth in 2023.

The name for the carbon-rich asteroid, designated in the scientific community as (101955) 1999 RQ36, is the winning entry in an international student contest. Nine-year-old Michael Puzio suggested the name because he imagined the Touch-and-Go Sample Mechanism (TAGSAM) arm and solar panels on OSIRIS-REx look like the neck and wings in drawings of Bennu, which Egyptians usually depicted as a gray heron. Puzio wrote the name suits the asteroid because it means "the ascending one," or "to shine."

(101955) 1999 RQ36

TAGSAM will collect a sample from Bennu and store it for return to Earth. The sample could hold clues to the origin of the solar system and the source of water and organic molecules that may have contributed to the development of life on Earth. The mission will be a vital part of NASA's plans to find, study, capture and relocate an asteroid for exploration by astronauts. NASA recently announced an asteroid initiative proposing a strategy to leverage human and robotic activities for the first human mission to an asteroid while also accelerating efforts to improve detection and characterization of asteroids.

"There were many excellent entries that would be fitting names and provide us an opportunity to educate the world about the exciting nature of our mission," said Dante Lauretta of the University of Arizona in Tucson, a contest judge and the principal investigator of the OSIRIS-REx mission. "The information about the composition of Bennu and the nature of its orbit will enable us to explore our past and better understand our future."

More than 8,000 students, all younger than 18, from more than 25 countries worldwide entered the "Name that Asteroid!" contest last year. Each contestant submitted one name with a maximum of 16 characters and a short explanation for the name.

OSIRIS-REx spacecraft description

The contest was a partnership with The Planetary Society in Pasadena, Calif.; the Massachusetts Institute of Technology Lincoln Laboratory in Lexington, Mass.; and the University of Arizona. The partners assembled a panel to review the submissions and submit a top choice to the International Astronomical Union (IAU) Committee for Small Body Nomenclature. The IAU is the governing body that officially names a celestial object.

"Bennu struck a chord with many of us right away," said Bruce Betts, director of projects for the Planetary Society and a contest judge. "While there were many great entries, the similarity between the image of the heron and the TAGSAM arm of OSIRIS-REx was a clever choice. The parallel with asteroids as both bringers of life and as destructive forces in the solar system also created a great opportunity to teach."

OSIRIS-REx spacecraft

The Lincoln Near Earth Asteroid Research Program survey team discovered the asteroid in 1999, early in NASA's Near-Earth Objects Observation Program, which detects and catalogs near-Earth asteroids and comets.

"The samples of Bennu returned by OSIRIS-REx will allow scientists to peer into the origin of the solar system and gain insights into the origin of life," said Jason Dworkin, an OSIRIS-REx project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

Goddard will provide overall mission management, systems engineering, and safety and mission assurance. The University of Arizona is the principal investigator institution. Lockheed Martin Space Systems of Denver will build the spacecraft. OSIRIS-REx is the third mission in NASA's New Frontiers Program. NASA's Marshall Space Flight Center in Huntsville, Ala., manages New Frontiers for NASA's Science Mission Directorate in Washington.

For more information on OSIRIS-REx, visit: http://osiris-rex.lpl.arizona.edu/

For information about the contest, visit: http://planetary.org/name

For more information about NASA's other asteroid-related missions, visit: http://www.nasa.gov

Images, Text, Credits: NASA.

Greetings, Orbiter.ch

mardi 30 avril 2013

Giant Gas Cloud in System NGC 6240











NASA - Chandra X-ray Observatory patch.

March 30, 2013

 Giant Gas Cloud in System NGC 6240

Scientists have used Chandra to make a detailed study of an enormous cloud of hot gas enveloping two large, colliding galaxies. This unusually large reservoir of gas contains as much mass as 10 billion Suns, spans about 300,000 light years, and radiates at a temperature of more than 7 million degrees.

This giant gas cloud, which scientists call a "halo," is located in the system called NGC 6240. Astronomers have long known that NGC 6240 is the site of the merger of two large spiral galaxies similar in size to our own Milky Way. Each galaxy contains a supermassive black hole at its center. The black holes are spiraling toward one another, and may eventually merge to form a larger black hole.

Another consequence of the collision between the galaxies is that the gas contained in each individual galaxy has been violently stirred up. This caused a baby boom of new stars that has lasted for at least 200 million years. During this burst of stellar birth, some of the most massive stars raced through their evolution and exploded relatively quickly as supernovas.

The scientists involved with this study argue that this rush of supernova explosions dispersed relatively high amounts of important elements such as oxygen, neon, magnesium, and silicon into the hot gas of the newly combined galaxies. According to the researchers, the data suggest that this enriched gas has slowly expanded into and mixed with cooler gas that was already there.

During the extended baby boom, shorter bursts of star formation have occurred. For example, the most recent burst of star formation lasted for about five million years and occurred about 20 million years ago in Earth’s timeframe. However, the authors do not think that the hot gas was produced just by this shorter burst.

What does the future hold for observations of NGC 6240? Most likely the two spiral galaxies will form one young elliptical galaxy over the course of millions of years. It is unclear, however, how much of the hot gas can be retained by this newly formed galaxy, rather than lost to surrounding space. Regardless, the collision offers the opportunity to witness a relatively nearby version of an event that was common in the early Universe when galaxies were much closer together and merged more often.

In this new composite image of NGC 6240, the X-rays from Chandra that reveal the hot gas cloud are colored purple. These data have been combined with optical data from the Hubble Space Telescope, which shows long tidal tails from the merging galaxies, extending to the right and bottom of the image.

Chandra X-ray Observatory spacecraft

A paper describing these new results on NGC 6240 is available online and appeared in the March 10, 2013 issue of The Astrophysical Journal. The authors in this study were Emanuele Nardini (Harvard-Smithsonian Center for Astrophysics, or CfA, Cambridge, MA and currently at Keele University, UK), Junfeng Wang (CfA and currently at Northwestern University, Evanston, IL), Pepi Fabbiano (CfA), Martin Elvis (CfA), Silvia Pellegrini (University of Bologna, Italy), Guido Risalti (INAF-Osservatorio Astrofisico di Arcetri, Italy and CfA), Margarita Karovska (CfA), and Andreas Zezas (University of Crete, Greece and CfA).

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

Read more/access all images: http://www.chandra.harvard.edu/photo/2013/ngc6240/

Chandra's Flickr photoset: http://www.flickr.com/photos/nasamarshall/sets/72157606205297786/

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

Images, Credits: X-ray: NASA / CXC / SAO / E. Nardini et al; Optical: NASA / STScI / Text, Credits: NASA / J.D. Harrington / Marshall Space Flight Center / Janet Anderson / Chandra X-ray Center / Megan Watzke.

Best regards, Orbiter.ch

lundi 29 avril 2013

Virgin Galactic Breaks Speed of Sound in First Rocket-Powered Flight of SPACESHIPTWO











Virgin Galactic logo.

April 29, 2013

Sir Richard Branson witnesses vehicle-proving milestone as company sets year-end goal for spaceflight 

First Rocket-Powered Flight of SPACESHIPTWO

Today, Virgin Galactic, the world’s first commercial spaceline owned by Sir Richard Branson’s Virgin Group and Abu Dhabi’s aabar Investments PJS, completed the first rocket-powered flight of its space vehicle, SpaceShipTwo (SS2). The test, conducted by teams from Scaled Composites (Scaled) and Virgin Galactic, officially marks Virgin Galactic’s entrance into the final phase of vehicle testing prior to commercial service from Spaceport America in New Mexico.

Spaceport America in New Mexico

“The first powered flight of Virgin Spaceship Enterprise was without any doubt, our single most important flight test to date,” said Virgin Galactic Founder Sir Richard Branson, who was on the ground in Mojave to witness the occasion. “For the first time, we were able to prove the key components of the system, fully integrated and in flight. Today’s supersonic success opens the way for a rapid expansion of the spaceship’s powered flight envelope, with a very realistic goal of full space flight by the year’s end. We saw history in the making today and I couldn’t be more proud of everyone involved.”

The test began at 7.02am local time when SS2 took off from Mojave Air and Space Port mated to WhiteKnightTwo (WK2), Virgin Galactic’s carrier aircraft. Piloting SS2 were Mark Stucky, pilot, and Mike Alsbury, co-pilot, who are test pilots for Scaled, which built SS2 for Virgin Galactic. At the WK2 controls were Virgin Galactic’s Chief Pilot Dave Mackay, assisted by Clint Nichols and Brian Maisler, co-pilot and flight test engineer, respectively, for Scaled.

video
First Rocket-Powered Flight of SPACESHIPTWO

Upon reaching 47,000 feet altitude and approximately 45 minutes into the flight, SS2 was released from WK2. After cross-checking data and verifying stable control, the pilots triggered ignition of the rocket motor, causing the main oxidizer valve to open and igniters to fire within the fuel case. At this point, SS2 was propelled forward and upward to a maximum altitude of 55,000 feet. The entire engine burn lasted 16 seconds, as planned. During this time, SS2 went supersonic, achieving Mach 1.2.

“We partnered with Virgin Galactic several years ago with the aspiration to transform and commercialize access to space for the broader public,” said His Excellency Khadem Al Qubaisi, Chairman of aabar Investments PJS. “Today’s test is another key milestone in realizing that aspiration. Our partnership goes from strength to strength, and is an excellent example of aabar’s desire to participate in the development of world class technologies that are commercially viable and strategically important, both for the company, its shareholders, and for Abu Dhabi.”

The entire rocket-powered flight test lasted just over 10 minutes, culminating in a smooth landing for SS2 in Mojave at approximately 8am local time.

“The rocket motor ignition went as planned, with the expected burn duration, good engine performance and solid vehicle handling qualities throughout,” said Virgin Galactic President & CEO George Whitesides. “The successful outcome of this test marks a pivotal point for our program. We will now embark on a handful of similar powered flight tests, and then make our first test flight to space.”

Virgin Galactic SpaceShip flight description (click on the image for enlarge)

In the coming months, the Virgin Galactic and Scaled test team will expand the spaceship’s powered flight envelope culminating in full space flight, which the companies anticipate will take place before the end of 2013.

“I’d like to congratulate the entire team,” said President of Scaled Kevin Mickey. “This milestone has been a long time coming and it’s only through the hard work of the team and the tremendous support of Virgin Galactic that we have been able to witness this important milestone. We look forward to all our upcoming tests and successes.”

About Virgin Galactic:

Virgin Galactic, owned by Sir Richard Branson’s Virgin Group and aabar Investments PJS , is on track to be the world’s first commercial spaceline. To date, the company has accepted more than $70 million in deposits from approximately 580 individuals, which is approximately 10% more than the total number of people who have ever gone to space. The new spaceship (SpaceShipTwo, VSS Enterprise) and carrier craft (WhiteKnightTwo, VMS Eve) have both been developed for Virgin Galactic’s vehicle fleet by Mojave-based Scaled Composites . Founded by Burt Rutan, Scaled developed SpaceShipOne, which in 2004 claimed the $10 million Ansari X Prize as the world’s first privately developed manned spacecraft. Virgin Galactic’s new vehicles, which will be manufactured by Virgin Galactic in Mojave, Calif., share much of the same basic design, but are being built to carry six customers, or the equivalent scientific research payload, on suborbital space flights. The vehicles will allow an out-of-the-seat, zero-gravity experience with astounding views of the planet from the black sky of space for tourist astronauts and a unique microgravity platform for researchers. The VSS Enterprise and VMS Eve test flight program is well under way, leading to Virgin Galactic commercial operations, which will be based at Spaceport America in New Mexico.

About aabar Investments PJS:

Headquartered in Abu Dhabi, aabar Investments PJS invests in various sectors including infrastructure, aviation, real estate, automotive, commodities, energy and financial services. IPIC acquired a stake in aabar in 2008 and has since progressively increased its stake to the current level of 95%. Since IPIC’s initial investment, aabar has made numerous investments including stakes in Daimler AG, Falcon Private Bank Ltd., Mercedes-Benz Grand Prix Limited, UniCredit S.p.A., Galactic Ventures LLC, XOJET, Inc., Glencore International plc and a portfolio of real estate projects.

For more information about Virgin Galactic, visit: http://www.virgingalactic.com/

Images, Video, Text, Credits: Virgin Galactic / MarsScientific.com and Clay Center Observatory.

Cheers, Orbiter.ch