vendredi 22 mars 2013

Water Mission extend its talents to carbon









ESA - SMOS Mission logo.

22 March 2013

ESA’s SMOS satellite is not only proving its worth by mapping soil moisture and ocean salinity, this multifaceted satellite has now shown that it can ‘see’ through vegetation to monitor wetlands for a better understanding of Earth’s carbon cycle.

It is widely appreciated that wetlands are important resources of freshwater and are rich in biodiversity.

Flooded forest, Czech Republic

However, it is less well known that wetlands also emit large quantities of methane – in fact, they contribute more methane to the atmosphere than any other natural source. Wetlands can also be both sources and sinks of carbon.

Although there is less methane in the atmosphere than carbon dioxide, methane is a much more powerful greenhouse gas. It is estimated that atmospheric methane was responsible for about 20% of the rise in global temperatures last century.

Methane emissions are mostly a result of human activity, but wetlands are thought to be responsible for about 20–40% of global emissions.

The waterlogged wetland soil is a prime habitat for anaerobic microbes. It is the anaerobic decomposition of organic matter covered by water that produces large quantities of methane.

Wetlands from SMOS

ESA’s SMOS water mission carries a novel microwave sensor to capture images of ‘brightness temperature’ to derive information on soil moisture and ocean salinity. This information is improving our understanding of water cycle.

However, SMOS is showing itself to be a very versatile tool and extending its usefulness to other areas of Earth science. 

Surpassing expectations, SMOS is also being used to monitor thin Arctic sea ice, map freezing soil, determine wind speeds under hurricanes and monitor ocean eddies. Extending the value of SMOS even further, studies have shown that monitoring wetlands could be added to the mission’s repertoire.

Because SMOS measures emitted radiation at a rather long wavelength of 21 cm, vegetation and the atmosphere have little affect on the observations. This means it is possible to look at how wetlands change over time.

Such information is extremely valuable for our understanding of the role that wetlands play in the carbon cycle and how they contribute to atmospheric methane.

Inundation from multiple satellites

Moreover, it has recently been demonstrated that observations from SMOS can reproduce features seen in complex datasets that include observations from many satellites such as that shown in the image on the left.

Catherine Prigent from the Paris Observatory explains, “SMOS offers the opportunity to implement fast and easy single satellite algorithms for monitoring wetland areas.

“This complements current methods of analysis that require a lot of work to blend the different products.”

A future SMOS product could be interesting for the GlobWetland II project. This programme, which is funded through ESA’s Earth Observation Data User Element, is helping to establish the Global Wetlands Observing System.

SMOS in orbit

Here, high-resolution optical data such as that from the Sentinel-2 mission, could be combined with the coarse-resolution SMOS observations to make optimal use of available remotely-sensed information.

By mapping wetlands and soil moisture, SMOS can also lead to a better understanding of the exchange processes between Earth’s surface and the atmosphere, including carbon fluxes.

Integrating SMOS observations into global carbon models is another novel application that was presented during the SMOS land application workshop held in February in Italy.

Related links:
Paris Observatory: http://www.obspm.fr/?lang=en

GlobWetland II: http://www.globwetland.org/index.php

Ramsar Convention: http://www.ramsar.org/cda/en/ramsar-european-rs-homeindex/main/ramsar/1%5E26097_4000_0__

Data User Element: http://due.esrin.esa.int/

Access SMOS data: http://earth.esa.int/SMOS/

More information:

Changes in land surface water dynamics since the 1990s and relation to population pressure: http://onlinelibrary.wiley.com/doi/10.1029/2012GL051276/abstract

Images, Text, Credits: ESA / C. Jimenez (Observatoire Paris) / Ramsar/ T. Salathé / F. Aires (Estellus)/F. Papa (IRD/LEGOS) / AOES Medialab.

Greetings, Orbiter.ch

jeudi 21 mars 2013

Progress M-17M corrected the orbit of the International Space Station












ROSCOSMOS - Russian Vehicles patch / ISS - International Space Station patch.

03/21/2013

In order to form a working orbit of the International Space Station before the flight of manned spacecraft Soyuz TMA-08M, the launch of which is scheduled for March 29, 2013, March 21, the correction of the ISS orbit.

The maneuver was carried out using an engine cargo spacecraft Progress M-17M

According to the ballistic-navigation service the Mission Control Center FSUE TsNIImash cargo ship engines were included in 4 hours 25 minutes Moscow time and worked for 673 seconds.

As a result of this dynamic operation ISS received a velocity increment of 1.5 m / s. The average height of the orbit increased by 2.6 km and reached 410.4 km.

International Space Station (ISS)

After maneuvering the ISS orbital parameters were:

• The minimum height above the Earth's surface - 403.8 km;

• The maximum height above the Earth's surface - 435.1 km;

• period - 92.72 minutes;

• inclination - 51.67 degrees.

Original text in Russian: http://www.federalspace.ru/main.php?id=2&nid=19966

Images, Text, Credits: Press Service of the Russian Federal Space Agency (Roscosmos PAO) / ROSCOSMOS / NASA / Translation: Orbiter.ch Aerospace.

Best regards, Orbiter.ch

Planck reveals an almost perfect Universe‏












ESA - Planck Mission patch.

21 March 2013

Acquired by ESA’s Planck space telescope, the most detailed map ever created of the cosmic microwave background – the relic radiation from the Big Bang – was released today revealing the existence of features that challenge the foundations of our current understanding of the Universe.

The image is based on the initial 15.5 months of data from Planck and is the mission’s first all-sky picture of the oldest light in our Universe, imprinted on the sky when it was just 380 000 years old.

At that time, the young Universe was filled with a hot dense soup of interacting protons, electrons and photons at about 2700ºC. When the protons and electrons joined to form hydrogen atoms, the light was set free. As the Universe has expanded, this light today has been stretched out to microwave wavelengths, equivalent to a temperature of just 2.7 degrees above absolute zero.

Cosmic microwave background seen by Planck

This ‘cosmic microwave background’ – CMB – shows tiny temperature fluctuations that correspond to regions of slightly different densities at very early times, representing the seeds of all future structure: the stars and galaxies of today.

According to the standard model of cosmology, the fluctuations arose immediately after the Big Bang and were stretched to cosmologically large scales during a brief period of accelerated expansion known as inflation.

Planck was designed to map these fluctuations across the whole sky with greater resolution and sensitivity than ever before. By analysing the nature and distribution of the seeds in Planck’s CMB image, we can determine the composition and evolution of the Universe from its birth to the present day.

Overall, the information extracted from Planck’s new map provides an excellent confirmation of the standard model of cosmology at an unprecedented accuracy, setting a new benchmark in our manifest of the contents of the Universe. 

Planck’s anomalous sky

But because precision of Planck’s map is so high, it also made it possible to reveal some peculiar unexplained features that may well require new physics to be understood.

“The extraordinary quality of Planck’s portrait of the infant Universe allows us to peel back its layers to the very foundations, revealing that our blueprint of the cosmos is far from complete. Such discoveries were made possible by the unique technologies developed for that purpose by European industry,” says Jean-Jacques Dordain, ESA’s Director General.

“Since the release of Planck’s first all-sky image in 2010, we have been carefully extracting and analysing all of the foreground emissions that lie between us and the Universe’s first light, revealing the cosmic microwave background in the greatest detail yet,” adds George Efstathiou of the University of Cambridge, UK.

One of the most surprising findings is that the fluctuations in the CMB temperatures at large angular scales do not match those predicted by the standard model – their signals are not as strong as expected from the smaller scale structure revealed by Planck.

video
Fluctuations in the CMB temperatures, animation by Martin White , U.S. Planck scientist

Another is an asymmetry in the average temperatures on opposite hemispheres of the sky. This runs counter to the prediction made by the standard model that the Universe should be broadly similar in any direction we look.

Furthermore, a cold spot extends over a patch of sky that is much larger than expected.

The asymmetry and the cold spot had already been hinted at with Planck’s predecessor, NASA’s WMAP mission, but were largely ignored because of lingering doubts about their cosmic origin.

“The fact that Planck has made such a significant detection of these anomalies erases any doubts about their reality; it can no longer be said that they are artefacts of the measurements. They are real and we have to look for a credible explanation,” says Paolo Natoli of the University of Ferrara, Italy.

Asymmetry and cold spot

“Imagine investigating the foundations of a house and finding that parts of them are weak. You might not know whether the weaknesses will eventually topple the house, but you’d probably start looking for ways to reinforce it pretty quickly all the same,” adds François Bouchet of the Institut d’Astrophysique de Paris.

One way to explain the anomalies is to propose that the Universe is in fact not the same in all directions on a larger scale than we can observe. In this scenario, the light rays from the CMB may have taken a more complicated route through the Universe than previously understood, resulting in some of the unusual patterns observed today.

video
A Journey of Light Through Space and Time

Video above: The Planck spacecraft is busy scanning our skies, picking up the afterglow of the big bang that created our universe. Credit: NASA / JPL-Caltech.

“Our ultimate goal would be to construct a new model that predicts the anomalies and links them together. But these are early days; so far, we don’t know whether this is possible and what type of new physics might be needed. And that’s exciting,” says Professor Efstathiou.

New cosmic recipe

Beyond the anomalies, however, the Planck data conform spectacularly well to the expectations of a rather simple model of the Universe, allowing scientists to extract the most refined values yet for its ingredients.

New cosmic recipe

Normal matter that makes up stars and galaxies contributes just 4.9% of the mass/energy density of the Universe. Dark matter, which has thus far only been detected indirectly by its gravitational influence, makes up 26.8%, nearly a fifth more than the previous estimate.

Conversely, dark energy, a mysterious force thought to be responsible for accelerating the expansion of the Universe, accounts for less than previously thought.

Finally, the Planck data also set a new value for the rate at which the Universe is expanding today, known as the Hubble constant. At 67.15 kilometres per second per megaparsec, this is significantly less than the current standard value in astronomy. The data imply that the age of the Universe is 13.82 billion years.

video
Planck Exposes Ancient Light of the Universe

Video above: The Planck mission was designed to measure the cosmic microwave background. Credit: NASA / JPL-Caltech.

“With the most accurate and detailed maps of the microwave sky ever made, Planck is painting a new picture of the Universe that is pushing us to the limits of understanding current cosmological theories,” says Jan Tauber, ESA’s Planck Project Scientist.

“We see an almost perfect fit to the standard model of cosmology, but with intriguing features that force us to rethink some of our basic assumptions.

“This is the beginning of a new journey and we expect that our continued analysis of Planck data will help shed light on this conundrum.”

Notes for editors:

A series of scientific papers describing the new results will be published on 22 March.

Background information on the topics discussed in this release is available by following the links on the right-hand side of this page.

The new data from Planck are based on the first 15.5 months of its all-sky surveys. Launched in 2009, Planck was designed to map the sky in nine frequencies using two state-of-the-art instruments: the Low Frequency Instrument (LFI), which includes the frequency bands 30–70 GHz, and the High Frequency Instrument (HFI), which includes the frequency bands 100–857 GHz. HFI completed its survey in January 2012, while LFI continues to operate.

Planck’s first all-sky image was released in 2010 and the first scientific data were released in 2011. Since then, scientists have been extracting the foreground emissions that lie between us and the Universe’s first light to reveal the CMB presented in this release. The next set of cosmology data will be released in early 2014.

The Planck Scientific Collaboration consists of all the scientists who have contributed to the development of the Planck mission, and who participate in the scientific exploitation of the Planck data during the proprietary period. These scientists are members of one or more of four consortia: the LFI Consortium, the HFI Consortium, the DK-Planck Consortium, and ESA's Planck Science Office. The two European-led Planck Data Processing Centres are located in Paris, France and Trieste, Italy.

The LFI consortium is led by N. Mandolesi, Agenzia Spaziale Italiana ASI, Italy (deputy PI: M. Bersanelli, Universita' degli Studi di Milano, Italy), and was responsible for the development and operation of the LFI instrument. The HFI consortium is led by J.L. Puget, Institut d’Astrophysique Spatiale in Orsay, France (deputy PI: F. Bouchet, Institut d'Astrophysique de Paris, France), and was responsible for the development and operation of the HFI instrument.

The Institut d’Astrophysique Spatiale in Orsay is a Unité Mixte de Recherche (UMR8617) of the CNRS (Centre National de la Recherche Scientifique) and the Université Paris-Sud 11. The Institut d’Astrophysique de Paris is a Unité Mixte de Recherche (UMR 7095) of the CNRS and the Université Pierre et Marie Curie of Paris.

Artist's view of ESA’s Planck space telescope

The development of the Planck mission was supported by substantial financial and technological contributions of ESA member states. More than 40% of the mission’s development cost was provided by the agencies supplying HFI and LFI. France and Italy, through the two leading funding agencies CNES and ASI, and the national research bodies, provided more than half of the national funding.

The contribution of ESA member states is even more significant for the scientific operation of the mission and the processing of its data.

ESA member states also provided key technologies such as the innovative cooler that enabled the mission’s instrumentation to be maintained atjust one-tenth of a degree above absolute zero (–273.15°C). Important technologies and payload elements were also contributed by NASA.

For more information about Planck mission, visit: http://www.esa.int/Our_Activities/Space_Science/Planck

Planck in depth: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=17

Planck Science Team: http://www.rssd.esa.int/index.php?project=Planck

Planck cosmology papers: http://www.sciops.esa.int/index.php?project=PLANCK&page=Planck_Published_Papers

Image, Videos, Text, Credits: ESA and the Planck Collaboration / NASA / JPL-Caltech.

Greetings, Orbiter.ch

Infrared and Iron














NASA - Chandra X-ray Observatory patch / NASA - Spitzer Space Telescope patch.

March 21, 2013


This composite image shows Spitzer infrared emission in pink and Chandra X-ray emission from iron in blue. The infrared emission is very similar in shape and location to X-ray emission (not shown here) from material that was expelled by the giant star companion to the white dwarf before the latter exploded. This material forms a disk around the center of the explosion as shown in the labeled version. This composite figure also shows a remarkably large and puzzling concentration of iron on the left side of the center of the remnant but not the right. The authors speculate that the cause of this asymmetry might be the "shadow" in iron that was cast by the companion star, which blocked the ejection of material. Previously, theoretical work has suggested this shadowing is possible for Type Ia supernova remnants.

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

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

Image, Text, Credit: NASA / J.D. Harrington / X-ray: NASA / CXC / NCSU / M.Burkey et al; Infrared: NASA / JPL-Caltech.

Cheers, Orbiter.ch

mercredi 20 mars 2013

Sun in the Way Will Affect Mars Missions in April












NASA patch.

March 20, 2013

The positions of the planets next month will mean diminished communications between Earth and NASA's spacecraft at Mars.

Mars will be passing almost directly behind the sun, from Earth's perspective. The sun can easily disrupt radio transmissions between the two planets during that near-alignment. To prevent an impaired command from reaching an orbiter or rover, mission controllers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., are preparing to suspend sending any commands to spacecraft at Mars for weeks in April. Transmissions from Mars to Earth will also be reduced.

The travels of Earth and Mars around the sun set up this arrangement, called a Mars solar conjunction, about once every 26 months.


This diagram illustrates the positions of Mars, Earth and the sun during a period that occurs approximately every 26 months, when Mars passes almost directly behind the sun from Earth's perspective. This arrangement, and the period during which it occurs, is called Mars solar conjunction. Radio transmissions between the two planets during conjunction are at risk of being corrupted by the sun's interference, so NASA Mars missions have a moratorium on sending commands to spacecraft on the surface of Mars or in orbit around Mars. Image credit: NASA/JPL-Caltech.

"This is our sixth conjunction for Odyssey," said Chris Potts of JPL, mission manager for NASA's Mars Odyssey, which has been orbiting Mars since 2001. "We have plenty of useful experience dealing with them, though each conjunction is a little different."

The Mars solar conjunctions that occur once about every 26 months are not identical to each other. They can differ in exactly how close to directly behind the sun Mars gets, and they can differ in how active the sun is. The sun's activity, in terms of sunspots and solar flares, varies on a 22-year cycle.

This year, the apparent angle between Mars and the sun (if you could see Mars against the glare of the sun--but don't try, because it's dangerous to the eyes) will slim to 0.4 degree on April 17. The sun is in a more active period of solar flares for its current cycle, compared to the 2011 conjunction, but this cycle has been relatively mild.

"The biggest difference for this 2013 conjunction is having Curiosity on Mars," Potts said. Odyssey and the Mars Reconnaissance Orbiter relay almost all data coming from Curiosity and the Mars Exploration Rover Opportunity, as well as conducting the orbiters' own science observations.

video
Mars in a Minute: What Happens When the Sun Blocks our Signal?

Video above: What is "solar conjunction," and how does it affect communications with our spacecraft at Mars? Learn more in this 60-second video.

Transmissions from Earth to the orbiters will be suspended while Mars and the sun are two degrees or less apart in the sky, from April 9 to 26, with restricted commanding during additional days before and after. Both orbiters will continue science observations on a reduced basis compared to usual operations. Both will receive and record data from the rovers. Odyssey will continue transmissions Earthward throughout April, although engineers anticipate some data dropouts, and the recorded data will be retransmitted later.

The Mars Reconnaissance Orbiter will go into a record-only mode on April 4. "For the entire conjunction period, we'll just be storing data on board," said Deputy Mission Manager Reid Thomas of JPL. He anticipates that the orbiter could have about 40 gigabits of data from its own science instruments and about 12 gigabits of data from Curiosity accumulated for sending to Earth around May 1.

NASA's Mars Exploration Rover Opportunity is approaching its fifth solar conjunction. Its team will send no commands between April 9 and April 26. The rover will continue science activities using a long-term set of commands to be sent beforehand.

"We are doing extra science planning work this month to develop almost three weeks of activity sequences for Opportunity to execute throughout conjunction," said Opportunity Mission Manager Alfonso Herrera of JPL. The activities during the conjunction period will not include any driving.

Curiosity, the newest asset on Mars, can also continue making science observations from the location where it will spend the conjunction period. Curiosity's controllers plan to suspend commanding from April 4 to May 1.

"We will maintain visibility of rover status two ways," said Torsten Zorn of JPL, conjunction planning leader for the mission's engineering operations team. "First, Curiosity will be sending daily beeps directly to Earth. Our second line of visibility is in the Odyssey relays."

JPL, a division of the California Institute of Technology, manages the projects operating both NASA Mars orbiters and both Mars rovers for NASA's Science Mission Directorate, Washington.

Image, Video , Text, Credits: NASA / JPL-Caltech / Guy Webster.

Best regards, Orbiter.ch

STEREO Watches the Sun Blast Comet PanSTARRS












NASA / ESA - SOHO Mission patch.

March 20, 2013

video
 STEREO Watches the Sun Blast Comet PanSTARRS

This movie from the Solar Terrestrial Relations Observatory (STEREO) shows comet PanSTARRS as it moved around the sun from March 10-15,2013 (repeated three times). The images were captured by the Heliospheric Imager (HI), an instrument that looks to the side of the sun to watch coronal mass ejections (CMEs) as they travel toward Earth, which is the unmoving bright orb on the right. The bright light on the left comes from the sun and the bursts from the left represent the solar material erupting off the sun in a CME. While it appears from STEREO’s point of view that the CME passes right by the comet, the two are not lying in the same plane, which scientists know since the comet’s tail didn’t move or change in response to the CME’s passage.

(Click on the image for enlarge)

Images above: Triptych made from three images of STEREO Behind's view of Comet PanSTARRS.

Still from STEREO Behind's Cor2 instrument showing the March 15, 2013 coronal mass ejection, or CME.

video

Video above: Sequence from STEREO Behind's Cor2 instrument showing three CMEs. Two occurred close together on March 12 and 13. The third, and largest, happened on March 15.

Multimedia items related to this story: http://svs.gsfc.nasa.gov/goto?11226

Images, Videos, Text, Credits: ESA / NASA's Goddard Space Flight Center.

Cheers, Orbiter.ch

Spiral Beauty Graced by Fading Supernova












ESO - European Southern Observatory logo.

20 March 2013

 Spiral galaxy NGC 1637

About 35 million light-years from Earth, in the constellation of Eridanus (The River), lies the spiral galaxy NGC 1637. Back in 1999 the serene appearance of this galaxy was shattered by the appearance of a very bright supernova. Astronomers studying the aftermath of this explosion with ESO’s Very Large Telescope at the Paranal Observatory in Chile have provided us with a stunning view of this relatively nearby galaxy.

Supernovae are amongst the most violent events in nature. They mark the dazzling deaths of stars and can outshine the combined light of the billions of stars in their host galaxies.

The supernova 1999em in the galaxy NGC 1637 (annotated)

In 1999 the Lick Observatory in California reported the discovery of a new supernova in the spiral galaxy NGC 1637. It was spotted using a telescope that had been specially built to search for these rare, but important cosmic objects [1]. Follow-up observations were requested so that the discovery could be confirmed and studied further. This supernova was widely observed and was given the name SN 1999em. After its spectacular explosion in 1999, the supernova’s brightness has been tracked carefully by scientists, showing its relatively gentle fading through the years.

The spiral galaxy NGC 1637 in the constellation of Eridanus

The star that became SN 1999em was very massive — more than eight times the mass of the Sun — before its death. At the end of its life its core collapsed, which then created a cataclysmic explosion [2].

Wide-field view of the sky around the spiral galaxy NGC 1637

When they were making follow up observations of SN 1999em astronomers took many pictures of this object with the VLT, which were combined to provide us with this very clear image of its host galaxy, NGC 1637. The spiral structure shows up in this image as a very distinct pattern of bluish trails of young stars, glowing gas clouds and obscuring dust lanes.

video
Zooming in on the spiral galaxy NGC 1637

Although at first glance NGC 1637 appears to be a fairly symmetrical object it has some interesting features. It is what astronomers classify as a lopsided spiral galaxy: the relatively loosely wound spiral arm at the top left of the nucleus stretches around it much further than the more compact and shorter arm at the bottom right, which appears dramatically slashed midway through its course.

video
A close look at the spiral galaxy NGC 1637

Elsewhere in the image the view is scattered with much closer stars and more distant galaxies that happen to lie in the same direction.

Notes:

[1] The supernova was discovered by the Katzman Automatic Imaging Telescope, at Lick Observatory on Mount Hamilton, California.

[2] SN 1999em is a core-collapse supernova classified more precisely as a Type IIp. The “p” stands for plateau, meaning supernovae of this type remain bright (on a plateau) for a relatively long period of time after maximum brightness.

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:

FORS instrument: http://www.eso.org/sci/facilities/paranal/instruments/fors/

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

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

Greetings, Orbiter.ch

mardi 19 mars 2013

NASA's LRO Sees GRAIL's Explosive Farewell

NASA - Lunar Reconnaissance Orbiter (LRO) patch.

March 19, 2013

Many spacecraft just fade away, drifting silently through space after their mission is over, but not GRAIL. NASA's twin GRAIL (Gravity Recovery and Interior Laboratory) spacecraft went out in a blaze of glory Dec. 17, 2012, when they were intentionally crashed into a mountain near the moon's north pole.

The successful mission to study the moon's interior took the plunge to get one last bit of science: by kicking up a cloud of dust and gas with each impact, researchers hoped to discover more about the moon's composition. However, with the moon about 380,000 kilometers (over 236,000 miles) away from Earth, the impact plumes would be difficult to observe from here. Fortunately, GRAIL had company –- NASA's Lunar Reconnaissance Orbiter (LRO) is orbiting the moon as well, busily making high-resolution maps of the lunar surface. With just three weeks notice, the LRO team scrambled to get LRO in the right place at the right time to witness GRAIL's fiery finale.

video
LAMP Observes GRAIL Impact

Video above: On Dec. 17, 2012, NASA's twin GRAIL spacecraft were deliberately crashed into the lunar surface traveling at nearly 4,000 mph. Another NASA spacecraft, Lunar Reconnaissance Orbiter, observed the impact using its LAMP instrument. The vertical rectangle in the animation represents the field-of-view of the LAMP instrument as determined by a thin slit-like aperture. LAMP is an imaging spectrometer so when looking directly down the slit sweeps across the lunar surface in what is call push-broom technique. The spacecraft rolled off to the side to put the slit on the lunar horizon. The LRO spacecraft crossed over the impact site at the right time for the first plume to get into the LAMP field-of-view. Credit: NASA/GSFC/Ernest Wright/Dan Gallagher.

"We were informed by the GRAIL team about three weeks prior to the impact exactly where the impact site would be," said LRO Project Scientist John Keller of NASA's Goddard Space Flight Center in Greenbelt, Md. "The GRAIL team's focus was on obtaining the highest resolution gravity measurements possible from the last few orbits of the GRAIL spacecraft, which led to uncertainty in the ultimate impact site until relatively late."

LRO is in a low orbit, only about 100 miles from the lunar surface at the time of the impact, and variations in gravity from massive features like lunar mountains tug on the spacecraft, altering its orbit. "We had planned a station-keeping maneuver – a periodic adjustment to the orbit to prevent the spacecraft from hitting the lunar surface -- a few days before the GRAIL impact," Keller said. "I asked the Flight Dynamics folks here at Goddard if they could combine the station-keeping maneuver with a phasing maneuver – firing the engines to slightly speed up or slow down the spacecraft so it is in the right place at the right time to see the impact. They said it didn’t really work; we'd have to do another station-keeping maneuver to compensate. Based on this, we were leaning against observing this impact because we were going to observe another lunar impact to end the European Space Agency's successful Herschel mission. That impact would have created a much larger plume because the Herschel spacecraft is more massive than GRAIL. However, ESA decided against the collision, so we went with the impact we had."

"By this time, we had lost about a week, and any time we fire the engines on LRO, mission safety requires us to schedule communications coverage from NASA's Deep Space Network," said Keller. Since so many spacecraft rely on the DSN, it's not easy to schedule with little notice.

"However, we had already planned the station-keeping maneuver, so we had already scheduled the DSN coverage," said Keller. "We postponed the station keeping until April 29, and the Flight Dynamics team turned on a dime, making the station-keeping maneuver into a phasing maneuver so we could observe the impact."


Animation above: LRO LROC before-and-after view of GRAIL-A (Ebb) impact. Credit: NASA/GSFC/Arizona State University.

The site was in shadow at the time of the impact, so the LRO team had to wait until the plumes rose high enough to be in sunlight before making the observation. The Lyman Alpha Mapping Project (LAMP), an ultraviolet imaging spectrograph on board the spacecraft, saw mercury and enhancements of atomic hydrogen in the plume.

"The mercury observation is consistent with what the LRO team saw from the LCROSS impact in October 2009," said Keller. "LCROSS (Lunar CRater Observation and Sensing Satellite) saw significant amounts of mercury, but the LCROSS site was at the bottom of the moon's Cabeus crater which hasn't seen sunlight for more than a billion years and is therefore extremely cold."

Mercury is a volatile, or easily vaporized, substance. Scientists propose that it could accumulate in cold, permanently shadowed craters like the one targeted for the LCROSS impact, but it was a surprise to see that it was also in an area that gets regular sunlight. "The issue for the GRAIL impact was not so much that mercury was found – you would expect it to be present as an element from the moon's formation, just like it is found on Earth," said Keller. "Rather, it is still reasonably concentrated near the surface instead of being driven off in an area where, for a very long time, the surface has been completely exposed to the space environment, including heat from the Sun, impacts from microscopic meteorites, and radiation."


Animation above: LRO LROC before-and-after view of GRAIL-B (Flow) impact. Credit: NASA/GSFC/Arizona State University.

"These new results help us continue to understand the nature of volatiles near the lunar poles," says Kurt Retherford, LAMP principal investigator at Southwest Research Institute, San Antonio, Texas. "In the last four years we have begun to understand that the amount of water ice near the polar regions is higher than previously thought. In addition to direct measurements of water from the LCROSS impact plume there were several other volatile species detected in the Cabeus crater cold-trapping region, including mercury atoms and hydrogen (H2) molecules detected with the LAMP instrument. While our results are still very new, our thinking is that the mercury detected by LAMP from the GRAIL site might be related to an enhancement at the poles caused by mercury atoms generally hopping across the surface and eventually migrating toward the colder polar regions. The detection of hydrogen atoms from the GRAIL impact plumes compared with H2 molecules in the LCROSS impact plume might tell us more about hydrogen and/or water near the poles, but this is a work in progress."

"This gives insight into how volatile material is transported around the moon," adds Keller. "It gives us a data point that helps constrain models of volatile transport, especially for models that describe how volatile material can get transported from warm to cold areas on the moon."

LRO's Lunar Reconnaissance Orbiter Camera (LROC) was able to make an image of the craters from the GRAIL impacts despite their relatively small size.


Animation above: LRO LROC before-and-after view of GRAIL impacts. Credit: NASA/GSFC/Arizona State University.

"The two spacecraft were relatively small -- cubes about the size of a washing machine with a mass of about 200 kg (440 lbs.) each at the time of impact," said Mark Robinson, LROC principal investigator at Arizona State University's School of Earth and Space Sciences, Tempe, Ariz. "When they were launched, the individual spacecraft mass was slightly more than 300 kg (661 lbs.), but each consumed just over 100 kg of fuel during the mission. The spacecraft were traveling about 6,070 kilometers per hour (3,771 mph) when they hit the surface. Both craters are relatively small, perhaps 4 to 6 meters (about 13 to 20 feet) in diameter and both have faint, dark, ejecta patterns, which is unusual. Fresh impact craters on the moon are typically bright, but these may be dark due to spacecraft material being mixed with the ejecta."

"Both impact sites lie on the southern slope of an unnamed massif (mountain) that lies south of the crater Mouchez and northeast of the crater Philolaus," adds Robinson. "The massif stands as much as 2,500 meters (about 8,202 feet) above the surrounding plains. The impact sites are at an elevation of about 700 meters (around 2,296 feet) and 1,000 meters (3,281 feet), respectively, about 500 to 800 meters (approximately 1,640 to 2,625 feet) below the summit. The two impact craters are about 2,200 meters (roughly 7,218 feet) apart. GRAIL B (renamed Flow) impacted about 30 seconds after GRAIL A (Ebb) at a site to the west and north of GRAIL A."

"The LRO spacecraft team, with much help and input from the GRAIL navigation team, did an excellent job of tailoring the timing of the LRO spacecraft's passage nearest the impact site to coincide with the impact events and needed delays for the plumes to rise up into sunlight," said Retherford. "Our two spacecraft teams communicated well with one another, which was crucial to making this coordinated observation a success.

Lunar Reconnaissance Orbiter. Image credit: NASA

LRO complemented the GRAIL mission in other ways as well. LRO's Diviner lunar radiometer observed the impact site and confirmed that the amount of heating of the surface there by the relatively small GRAIL spacecraft was within expectations. LRO's Lunar Orbiter Laser Altimeter (LOLA) instrument bounced laser pulses off the surface to build up a precise map of the lunar terrain, including the three-dimensional structure of features like mountains and craters. "Combining the LRO LOLA topography map with GRAIL's gravity map yields some very interesting results," said Keller. "You expect that areas with mountains will have a little stronger gravity, while features like craters will have a little less. However, when you subtract out the topography, you get another map that reveals gravity differences that are not tied to the surface. It gives insight into structures deeper in the moon's interior."

The research was funded by the LRO mission, currently under NASA's Science Mission Directorate at NASA Headquarters in Washington. LRO is managed by NASA's Goddard Space Flight Center in Greenbelt, Md.

For more information about Lunar Reconnaissance Orbiter (LRO), visit: http://www.nasa.gov/mission_pages/LRO

Images (mentioned), Video (mentioned), Text, Credit: NASA's Goddard Space Flight Center / Nancy Neal-Jones / Bill Steigerwald.

Best regards, Orbiter.ch

Herschel Discovers Some of the Youngest Stars Ever Seen










NASA / ESA - Herschel Exploring the Cold Universe patch.

March 19, 2013

Astronomers have found some of the youngest stars ever seen, thanks to the Herschel space observatory, a European Space Agency mission with important NASA contributions.

Observations from NASA's Spitzer Space Telescope and the Atacama Pathfinder Experiment (APEX) telescope in Chile, a collaboration involving the Max Planck Institute for Radio Astronomy in Germany, the Onsala Space Observatory in Sweden, and the European Southern Observatory in Germany, contributed to the findings.

Dense envelopes of gas and dust surround the fledging stars known as protostars, making their detection difficult. The 15 newly observed protostars turned up by surprise in a survey of the biggest site of star formation near our solar system, located in the constellation Orion. The discovery gives scientists a peek into one of the earliest and least understood phases of star formation.


Astronomers have found some of the youngest stars ever seen thanks to the Herschel space observatory, a European Space Agency mission with important NASA contributions. Dense envelopes of gas and dust surround the fledging stars known as protostars, making their detection difficult until now. The discovery gives scientists a window into the earliest and least understood phases of star formation. Image credit: NASA/ESA/ESO/JPL-Caltech/Max-Planck Institute for Astronomy.

"Herschel has revealed the largest ensemble of such young stars in a single star-forming region," said Amelia Stutz, lead author of a paper to be published in The Astrophysical Journal and a postdoctoral researcher at the Max Planck Institute for Astronomy in Heidelberg, Germany. "With these results, we are getting closer to witnessing the moment when a star begins to form."

Stars spring to life from the gravitational collapse of massive clouds of gas and dust. This changeover from stray, cool gas to the ball of super-hot plasma we call a star is relatively quick by cosmic standards, lasting only a few hundred thousand years. Finding protostars in their earliest, most short-lived and dimmest stages poses a challenge.

Astronomers long had investigated the stellar nursery in the Orion Molecular Cloud Complex, a vast collection of star-forming clouds, but had not seen the newly identified protostars until Herschel observed the region.

"Previous studies have missed the densest, youngest and potentially most extreme and cold protostars in Orion," Stutz said. "These sources may be able to help us better understand how the process of star formation proceeds at the very earliest stages, when most of the stellar mass is built up and physical conditions are hardest to observe."

Herschel spied the protostars in far-infrared, or long-wavelength, light, which can shine through the dense clouds around burgeoning stars that block out higher-energy, shorter wavelengths, including the light our eyes see.

Herschel space observatory. Image credit: ESA / NASA

The Herschel Photodetector Array Camera and Spectrometer (PACS) instrument collected infrared light at 70 and 160 micrometers in wavelength, comparable to the width of a human hair. Researchers compared these observations to previous scans of the star-forming regions in Orion taken by Spitzer. Extremely young protostars identified in the Herschel views but too cold to be picked up in most of the Spitzer data were further verified with radio wave observations from the APEX ground telescope.

"Our observations provide a first glimpse at protostars that have just begun to 'glow' at far-infrared wavelengths," said paper coauthor Elise Furlan, a postdoctoral research associate at the National Optical Astronomy Observatory in Tucson, Ariz.

Of the 15 newly discovered protostars, 11 possess very red colors, meaning their light output trends toward the low-energy end of the electromagnetic spectrum. This output indicates the stars are still embedded deeply in a gaseous envelope, meaning they are very young. An additional seven protostars previously seen by Spitzer share this characteristic. Together, these 18 budding stars comprise only five percent of the protostars and candidate protostars observed in Orion. That figure implies the very youngest stars spend perhaps 25,000 years in this phase of their development, a mere blink of an eye considering a star like our sun lives for about 10 billion years.

Researchers hope to document chronologically each stage of a star's development rather like a family album, from before birth to early infancy, when planets also take shape.

"With these recent findings, we add an important missing photo to the family album of stellar development," said Glenn Wahlgren, Herschel Program Scientist at NASA Headquarters in Washington. "Herschel has allowed us to study stars in their infancy."

Herschel is a European Space Agency mission, with science instruments provided by a consortia of European institutes with important participation by NASA. NASA's Herschel Project Office is based at the agency's Jet Propulsion Laboratory in Pasadena, Calif. JPL is a division of the California Institute of Technology, Pasadena.

For more about Herschel, visit: http://www.nasa.gov/herschel , http://www.esa.int/SPECIALS/Herschel/index.html and http://www.herschel.caltech.edu

Images (mentioned), Text, Credit: NASA / J.D. Harrington / JPL / Whitney Clavin.

Greetings, Orbiter.ch

Black hole-star pair orbiting at dizzying speed‏














ESA - XMM-Newton Mission patch / NASA - Swift Mission patch.

19 March 2013

video
 MAXI J1659­–152

ESA’s XMM-Newton space telescope has helped to identify a star and a black hole that orbit each other at the dizzying rate of once every 2.4 hours, smashing the previous record by nearly an hour.

The black hole in this compact pairing, known as MAXI J1659-152, is at least three times more massive than the Sun, while its red dwarf companion star has a mass only 20% that of the Sun. The pair is separated by roughly a million kilometres.

The duo were discovered on 25 September 2010 by NASA’s Swift space telescope and were initially thought to be a gamma-ray burst. Later that day, Japan’s MAXI telescope on the International Space Station found a bright X-ray source at the same place.

ESA’s XMM-Newton space telescope

More observations from ground and space telescopes, including XMM-Newton, revealed that the X-rays come from a black hole feeding off material ripped from a tiny companion.

Several regularly-spaced dips in the emission were seen in an uninterrupted 14.5 hour observation with XMM-Newton, caused by the uneven rim of the black hole’s accretion disc briefly obscuring the X-rays as the system rotates, its disc almost edge-on along XMM-Newton’s line of sight.

From these dips, an orbital period of just 2.4 hours was measured, setting a new record for black hole X-ray binary systems. The previous record-holder, Swift J1753.5–0127, has a period of 3.2 hours.

The black hole and the star orbit their common centre of mass. Because the star is the lighter object, it lies further from this point and has to travel around its larger orbit at a breakneck speed of two million kilometres per hour – it is the fastest moving star ever seen in an X-ray binary system. On the other hand, the black hole orbits at ‘only’ 150 000 km/h.

“The companion star revolves around the common centre of mass at a dizzying rate, almost 20 times faster than Earth orbits the Sun. You really wouldn’t like to be on such a merry-go-round in this Galactic fair!” says lead author Erik Kuulkers of ESA’s European Space Astronomy Centre in Spain.

His team also saw that they lie high above the Galactic plane, out of the main disc of our spiral Galaxy, an unusual characteristic shared only by two other black-hole binary systems, including Swift J1753.5–0127.

NASA’s Swift space telescope

“These high galactic latitude locations and short orbital periods are signatures of a potential new class of binary system, objects that may have been kicked out of the Galactic plane during the explosive formation of the black hole itself,” says Dr Kuulkers.

Returning to MAXI J1659−152, the quick response of XMM-Newton was key in being able to measure the remarkably short orbital period of the system.

“Observations started at tea-time, just five hours after we received the request to begin taking measurements, and continued until breakfast the next day. Without this rapid response it would not have been possible to discover the fastest rotation yet known for any binary system with a black hole,” adds Norbert Schartel, ESA’s XMM-Newton project scientist.

Related links:

XMM-Newton overview: http://www.esa.int/Our_Activities/Space_Science/XMM-Newton_overview

XMM-Newton image gallery: http://xmm.esac.esa.int/external/xmm_science/gallery/public/index.php

XMM-Newton in-depth: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=23

NASA Swift: http://www.nasa.gov/mission_pages/swift/main/index.html

MAXI: http://www.nasa.gov/mission_pages/station/research/experiments/MAXI.html

Images, Text, Credits: ESA / NASA.

Cheers, Orbiter.ch

lundi 18 mars 2013

Kepler Supernova Remnant












NASA - Chandra X-ray Observatory patch.

March 18, 2013


This is the remnant of Kepler's supernova, the famous explosion that was discovered by Johannes Kepler in 1604. The red, green and blue colors show low, intermediate and high energy X-rays observed with NASA’s Chandra X-ray Observatory, and the star field is from the Digitized Sky Survey.

As reported in our press release, a new study has used Chandra to identify what triggered this explosion. It had already been shown that the type of explosion was a so-called Type Ia supernova, the thermonuclear explosion of a white dwarf star. These supernovas are important cosmic distance markers for tracking the accelerated expansion of the Universe.

However, there is an ongoing controversy about Type Ia supernovas. Are they caused by a white dwarf pulling so much material from a companion star that it becomes unstable and explodes? Or do they result from the merger of two white dwarfs?

The new Chandra analysis shows that the Kepler supernova was triggered by an interaction between a white dwarf and a red giant star. The crucial evidence from Chandra was a disk-shaped structure near the center of the remnant. The researchers interpret this X-ray emission to be caused by the collision between supernova debris and disk-shaped material that the giant star expelled before the explosion. Another possibility was that the structure is just debris from the explosion.

The disk structure seen by Chandra in X-rays is very similar in both shape and location to one observed in the infrared by the Spitzer Space Telescope. This composite image shows Spitzer data in pink and Chandra data from iron emission in blue. The disk structure is identified with a label.

Chandra X-ray Observatory

This composite figure also shows a remarkably large and puzzling concentration of iron on one side of the center of the remnant but not the other. The authors speculate that the cause of this asymmetry might be the "shadow" in iron that was cast by the companion star, which blocked the ejection of material. Previously, theoretical work has suggested this shadowing is possible for Type Ia supernova remnants.

The authors also produced a video showing a simulation of the supernova explosion as it interacts with material expelled by the giant star companion. It was assumed that the bulk of this material was expelled in a disk-like structure, with a gas density that is ten times higher at the equator, running from left to right, than at the poles. This simulation was performed in two dimensions and then projected into three dimensions to give an image that can be compared with observations. The good agreement with observations supports their interpretation of the data.

These results were published online and in the February 10th, 2013 issue of The Astrophysical Journal.

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

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

Images, Credits: X-ray: NASA / CXC / NCSU / M.Burkey et al; Infrared: NASA / JPL-Caltech / Text, Credits: NASA / J.D. Harrington / Marshall Space Flight Center / Janet Anderson / Chandra X-ray Center / Megan Watzke.

Greetings, Orbiter.ch

Curiosity Mars Rover Sees Trend in Water Presence












NASA - Mars Science Laboratory (MSL) patch.

March 18, 2013

NASA's Mars rover Curiosity has seen evidence of water-bearing minerals in rocks near where it had already found clay minerals inside a drilled rock.

Last week, the rover's science team announced that analysis of powder from a drilled mudstone rock on Mars indicates past environmental conditions that were favorable for microbial life. Additional findings presented today (March 18) at a news briefing at the Lunar and Planetary Science Conference in The Woodlands, Texas, suggest those conditions extended beyond the site of the drilling.

Using infrared-imaging capability of a camera on the rover and an instrument that shoots neutrons into the ground to probe for hydrogen, researchers have found more hydration of minerals near the clay-bearing rock than at locations Curiosity visited earlier.


On this image of the rock target 'Knorr,' color coding maps the amount of mineral hydration indicated by a ratio of near-infrared reflectance intensities measured by the Mast Camera (Mastcam) on NASA's Mars rover Curiosity. Image credit: NASA/JPL-Caltech/MSSS/ASU.

The rover's Mast Camera (Mastcam) can also serve as a mineral-detecting and hydration-detecting tool, reported Jim Bell of Arizona State University, Tempe. "Some iron-bearing rocks and minerals can be detected and mapped using the Mastcam's near-infrared filters."

Ratios of brightness in different Mastcam near-infrared wavelengths can indicate the presence of some hydrated minerals. The technique was used to check rocks in the "Yellowknife Bay" area where Curiosity's drill last month collected the first powder from the interior of a rock on Mars. Some rocks in Yellowknife Bay are crisscrossed with bright veins.

"With Mastcam, we see elevated hydration signals in the narrow veins that cut many of the rocks in this area," said Melissa Rice of the California Institute of Technology, Pasadena. "These bright veins contain hydrated minerals that are different from the clay minerals in the surrounding rock matrix."

The Russian-made Dynamic Albedo of Neutrons (DAN) instrument on Curiosity detects hydrogen beneath the rover. At the rover's very dry study area on Mars, the detected hydrogen is mainly in water molecules bound into minerals. "We definitely see signal variation along the traverse from the landing point to Yellowknife Bay," said DAN Deputy Principal Investigator Maxim Litvak of the Space Research Institute, Moscow. "More water is detected at Yellowknife Bay than earlier on the route. Even within Yellowknife Bay, we see significant variation."

Findings presented today from the Canadian-made Alpha Particle X-ray Spectrometer (APXS) on Curiosity's arm indicate that the wet environmental processes that produced clay at Yellowknife Bay did so without much change in the overall mix of chemical elements present. The elemental composition of the outcrop Curiosity drilled into matches the composition of basalt. For example, it has basalt-like proportions of silicon, aluminum, magnesium and iron. Basalt is the most common rock type on Mars. It is igneous, but it is also thought to be the parent material for sedimentary rocks Curiosity has examined.

Hydration Map, Based on Mastcam Spectra, for broken rock 'Tintina'

Image above: On this image of the broken rock called "Tintina," color coding maps the amount of mineral hydration indicated by a ratio of near-infrared reflectance intensities measured by the Mast Camera (Mastcam) on NASA's Mars rover Curiosity. The color scale on the right shows the assignment of colors for relative strength of the calculated signal for hydration. The map shows a strong signal for hydration is associated with the surface that was exposed when the rock was broken by the rover driving over it. That freshly exposed surface displays a bright material that may be the same as similarly bright material filling pale veins in the nearby bedrock of the "Yellowknife Bay" area. The size of the rock is roughly 1.2 inches by 1.6 inches (3 centimeters by 4 centimeters). This image is a Mastcam observation of Tintina during the 160th Martian day, or sol, of the rover's work on Mars (Jan. 17, 2013). The spectral data for assessing hydration come from Mastcam observations through a series of narrow-waveband filters on Sol 162 (Jan. 19, 2013). Image credit: NASA/JPL-Caltech/MSSS/ASU.

"The elemental composition of rocks in Yellowknife Bay wasn't changed much by mineral alteration," said Curiosity science team member Mariek Schmidt of Brock University, Saint Catharines, Ontario, Canada.

A dust coating on rocks had made the composition detected by APXS not quite a match for basalt until Curiosity used a brush to sweep the dust away. After that, APXS saw less sulfur.

"By removing the dust, we've got a better reading that pushes the classification toward basaltic composition," Schmidt said. The sedimentary rocks at Yellowknife Bay likely formed when original basaltic rocks were broken into fragments, transported, re-deposited as sedimentary particles, and mineralogically altered by exposure to water.

NASA's Mars Science Laboratory Project is using Curiosity to investigate whether an area within Mars' Gale Crater has ever offered an environment favorable for microbial life. Curiosity, carrying 10 science instruments, landed seven months ago to begin its two-year prime mission. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the project for NASA's Science Mission Directorate in Washington.

Rock Target 'Knorr' Near Curiosity in Rover's Self-Portrait

Image above: The location of a rock target called "Knorr" is indicated on this self-portrait of the Curiosity rover in the "Yellowknife Bay" area. Scientists used Curiosity's Mast Camera (Mastcam) to study spectral characteristics of Knorr. This self-portrait is a mosaic of images taken by Curiosity's Mars Hand Lens Imager (MAHLI) camera during the 177th Martian day, or sol, of Curiosity's work on Mars (Feb. 3, 2013). An unannotated version is at: http://www.nasa.gov/mission_pages/msl/multimedia/pia16763.html. Image credit: NASA/JPL-Caltech/MSSS.

For more about the mission, visit: http://www.jpl.nasa.gov/msl , http://marsprogram.jpl.nasa.gov/msl and http://www.nasa.gov/msl .

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

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

Best regards, Orbiter.ch