INTEGRAL deciphers diffuse signature of cosmic-ray electrons

ESA - INTEGRAL Mission patch.

21 Dec 2011

Astronomers exploiting six years worth of data from ESA's INTEGRAL mission have pinned down the individual processes contributing to the high-energy Galactic interstellar emission produced by cosmic-ray electrons. Deciphering each of the different physical mechanisms at play at hard X-ray and soft gamma-ray wavelengths represents a crucial step towards an increasingly detailed picture of the population of high-energy particles permeating the Milky Way.

Cosmic rays are highly-energetic charged particles that pervade galaxies, including our own Galaxy, the Milky Way, and can also escape from them and travel across intergalactic space. They are important players in regulating global galactic properties such as the heating balance and the total energy budget, and have been subject to intense investigation ever since their discovery in 1912.

The hard X-ray sky as seen with INTEGRAL / SPI. Credits: ESA / INTEGRAL / SPI

Researchers study these particles either directly, by detecting the tracks that arise from collisions with material in the Earth's atmosphere, or indirectly, by tracing the radiation emitted when cosmic rays interact with different components of a galaxy – for example, other particles, photons, magnetic fields. In the Milky Way, these phenomena are among the primary sources of the distinctive 'diffuse' emission that is seen along the Galactic Plane, at both the low energy (radio, microwave) and high energy (hard X-ray, gamma ray) ends of the electromagnetic spectrum.

This 'glow' is due to a combination of many different processes. Extensive observations across many wavelengths, as well as detailed physical modelling, are required to disentangle all contributions and to help solve the puzzle of the charged particles that fill our Galaxy.

"The diffuse emission at hard X-ray and soft gamma-ray wavelengths is an excellent tracer of cosmic-ray electrons and their antiparticles, the positrons, a minor but very significant fraction of the high-energy particle population in the Milky Way," explains Laurent Bouchet from Université de Toulouse and Institut de Recherche en Astrophysique et Planétologie (IRAP) in France. Bouchet and his international team exploited data from ESA's INTEGRAL mission, probing the entire sky at energies between 20 keV and 2.4 MeV. Exploring the diffuse emission in this energy range is one of the main science goals of the INTEGRAL mission, and after almost a decade of operation the mission has finally achieved the unprecedented sensitivity required to push this inquiry to the next level.

The study conducted by Bouchet and his collaborators relies on data collected with the Spectrometer on board INTEGRAL (SPI) over a time span of six years. "Such a long exposure allowed us to isolate, with very high precision, the different physical processes that account for the total emission in the spectral window probed by INTEGRAL," he adds.

The first step in the complex analysis performed by the team consists of a careful scrutiny of the data to remove all point sources, both galactic and extragalactic, that radiate at these wavelengths. In this context, point sources represent a contamination of the diffuse signal produced by cosmic rays. "We have identified a few hundred sources across the entire sky and established that their contribution is dominant at the lowest energies examined in this work, between 20 and 100 keV," notes Bouchet. After point-source removal, the observed diffuse emission was compared with model predictions, in order to break it down into the individual physical processes that contribute to it.

Graphic above: Different contributions to the total emission at hard X-ray and soft gamma-ray energies, as measured with INTEGRAL/SPI. Courtesy of L. Bouchet (Univ. Toulouse and IRAP).

"Interestingly, we found a major contribution due to Inverse Compton (IC) scattering, thus confirming what early INTEGRAL data had hinted at a few years ago," comments Andrew Strong from the Max-Planck Institut für Extraterrestrische Physik (MPE) in Germany. IC scattering consists of collisions between highly energetic electrons (or positrons) and low-energy photons present in interstellar space, which result in the electrons transferring part of their energy to the photons, thus 'boosting' them to X- and gamma-ray wavelengths. Cosmic-ray electrons interact via IC scattering with infrared and visible photons emitted by stars, and with the ubiquitous photons of the cosmic microwave background radiation.

The team made use of a very detailed model of the interstellar radiation field in the inner part of the Galaxy, a crucial ingredient to be taken into account in order to achieve a thorough physical interpretation of the observed emission. "Together with the latest models and improved data analysis techniques, the new INTEGRAL data allowed us to unequivocally identify IC scattering as the principal mechanism producing diffuse emission between 100 and 200 keV, as well as between 600 keV and 2 MeV," adds Strong.

Besides the clear feature of IC scattering, the data also exhibit the well studied signatures of other emission processes arising in this spectral band – the annihilation of positrons with electrons and the radioactive decay of some unstable atomic nuclei. When positrons and electrons collide, two things may happen: they may destroy each other immediately, releasing a pair of photons each with an energy of 511 keV; alternatively, they may create an unstable and short-lived two-particle system called positronium, which soon decays into two or more photons, producing a distinctive continuum emission spectrum up to 511 keV. At energies above 1 MeV, the data also exhibit characteristic decay features of two unstable isotopes of aluminium (26Al) and iron (60Fe). This indicates the presence of these radioactive nuclei - the products of recent nucleosynthesis in supernova explosions - throughout the diffuse interstellar medium of the Milky Way.

"In addition to these mechanisms, the data require a further component to be taken into account at low energies, below 50 keV," notes Bouchet. "This is most likely due to the superposition of many unresolved faint sources, as pointed out by previous studies based on data from the IBIS imager on board INTEGRAL," he adds. Stars with very hot coronae and cataclysmic variable stars are the main objects contributing to this unresolved emission.

Artist's impression of Integral. Credit: ESA

The study of Bouchet and collaborators enabled models of cosmic ray propagation to be tested in this portion of the electromagnetic spectrum in greater detail than previously possible. "The data demonstrate that our current understanding of the properties of cosmic-ray electrons in the Milky Way is qualitatively correct," notes Strong. As INTEGRAL keeps scanning the high-energy sky, even longer exposures will be available in the future. "With more data and improved analysis methodology, we plan to explore quantitatively the distribution of cosmic-ray electrons across the Galaxy, narrowing down important parameters such as the size of the Galactic region within which the particles are confined," he adds.

Ultimately, it is essential to verify that the data fit well within the physical scenario suggested by other observations. In particular, there is a consensus on the general picture provided by both INTEGRAL and the Large Area Telescope (LAT) on board NASA's Fermi Gamma-ray Space Telescope. Sensitive to gamma rays between 20 MeV and 300 GeV, Fermi-LAT observes the sky at higher energies than INTEGRAL, and the agreement reached by these two complementary missions is very encouraging.

"This long-awaited result showcases INTEGRAL's uniqueness in probing such a crucial spectral window," comments Chris Winkler, INTEGRAL Project Scientist at ESA. "The large amount of data accumulated by INTEGRAL is now revealing the mission's full potential for exciting results and discoveries."

Notes for editors:

The study presented here is based on observations performed with the Spectrometer on board INTEGRAL (SPI) between 22 February 2003 and 2 January 2009. The data probe the entire sky at energies between 20 keV and 2.4 MeV.

The data were compared to model predictions obtained with GALPROP, a publicly available code for calculating the propagation of cosmic-ray nuclei, antiprotons, electrons and positrons. The code also computes diffuse gamma-ray and synchrotron emission resulting from the cosmic rays. The first version of GALPROP was developed in the mid-1990s by Andrew W. Strong (MPE, Germany) and Igor V. Moskalenko (Stanford University, USA), both co-authors of the paper presented here. The code is currently maintained by a small team of researchers. In particular, GALPROP includes the most advanced model presently available of the interstellar radiation in the inner Galaxy, which has been developed by Troy A. Porter (Stanford University, USA), who is also a co-author of the paper presented here.

INTEGRAL is an ESA project with instruments and science data centre funded by ESA Member States (especially the Principal Investigator countries: Denmark, France, Germany, Italy, Spain, Switzerland) and Poland, and with the participation of Russia and the USA.

Related publications:

L. Bouchet, et al., "Diffuse Emission Measurement with the SPectrometer on Integral as an Indirect Probe of Cosmic-ray Electrons and Positrons", 2011, The Astrophysical Journal, 739, 29.

For more information about INTEGRAL, visit: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=21

Images (mentioned), Text, Credits: Université de Toulouse and Institut de Recherche en Astrophysique et Planétologie (IRAP), Laurent Bouchet / Max-Planck Institut für Extraterrestrische Physik (MPE), Andrew W. Strong / INTEGRAL Project Scientist Research and Scientific Support Department Directorate of Science and Robotic Exploration ESA, Chris Winkler.

Best regards, Orbiter.ch

Launch of manned spacecraft Soyuz TMA-03M

ROSCOSMOS - Soyuz TMA-03M Mission patch.

12/21/2011

 Soyuz TMA-03M on a launch pad

December 21 at 17.16.15 GMT on a launch pad site Baikonur was put space rocket (ILV) Soyuz-FG with transport manned spacecraft (TLC) Soyuz TMA-03M (Commander Oleg Kononenko (Roscosmos), flight engineers Andre Kuipers (ESA) and Donald Pettit (NASA)).

Image above: The crew headed for the elevator, commander Oleg Kononenko, flight engineers, astronauts ship Andre Kuipers (ESA) and Donald Pettit (NASA) will take their places in the ship.

Soyuz TMA-03M Launch

After 528 seconds of flight rocket TPK Soyuz TMA-03M cleanly separated from the third stage to orbit an artificial satellite.

Soyuz TMA manned transport spacecraft cutaway

Docking of the Soyuz TMA-03M to the International Space Station is scheduled for December 23 this year at 19:22 Moscow time (10:22 a.m. EST on Friday).

Expedition 30 Commander Dan Burbank and Flight Engineers Anton Shkaplerov and Anatoly Ivanishin will welcome their new crewmates aboard the station a little while later when they open the hatches about 1 p.m.

Pettit, Kononenko and Kuipers are scheduled to live and work aboard the orbiting laboratory until May. They will become members of the Expedition 31 crew under the command of Kononenko when Burbank, Shkaplerov and Ivanishin undock in their Soyuz TMA-22 spacecraft in March.

Read more about Expedition 30: http://www.nasa.gov/mission_pages/station/expeditions/expedition30/index.html

Send a holiday postcard to the station crew: http://www.nasa.gov/externalflash/postcard/

More information about the International Space Station (ISS), visit: http://www.nasa.gov/mission_pages/station/main/index.html

Original text in Russian: http://www.federalspace.ru/main.php?id=2&nid=18481

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

Greetings, Orbiter.ch

A Chinese Long March 3B rocket launch the Nigcomsat 1R satellite for Nigeria

CNSA - China National Space Administration logo.

Dec. 20, 2011

China launched a massive Nigerian communications satellite Monday to link Africans with television programming, education services and navigation signals.

Warning! This video has inaudible sound, turn off your speaker!

Long March 3B rocket launch the Nigcomsat 1R

Liftoff occurred at about 16:41 GMT (11:41 a.m. EST) Monday, or just after midnight Beijing time on Tuesday.

Manufactured by the China Academy of Space Technology, the Nigcomsat 1R satellite will replace a craft that lost power and failed in November 2008, less than 18 months after its launch on a Chinese rocket.

Long March 3B rocket launch

Nigcomsat Ltd., a company chartered by the Nigerian government, will operate the satellite for up to 15 years.

Nigcomsat 1R "will provide optimal and cost effective voice, data, video, Internet and application services solutions," the satellite's operator said.

 Logo of the satellite on the rocket fairing

An 18-story Long March 3B rocket will streak into space from the Xichang launch base in Sichuan province in southwestern China.

The three-stage rocket, boosted off the launch pad by four strap-on engines, will reach orbit 10 minutes into the mission. The rocket's hydrogen-fueled third stage will ignite a second time to place Nigcomsat 1R in an an oval-shaped transfer orbit with a low point of 124 miles, a high point of 26,092 miles and an inclination of 24.8 degrees, according to China Great Wall Industry Corp., the state-owned commercial sales firm for the Long March rocket family.

Separation of the 11,243-pound satellite is scheduled less than 26 minutes after liftoff. Nigcomsat 1R will ultimately be positioned in geosynchronous orbit over the equator at 42.5 degrees east longitude.

Nigcomsat 1R satellite

Nigcomsat 1R is based on China's DFH-4 spacecraft platform. China has reached agreements to build DFH-4 communications satellites for several non-traditional players in the space industry, including Pakistan, Nigeria, Venezuela, Laos and Bolivia.

Nigcomsat 1R's communications package includes 28 active transponders and seven antennas reaching across sub-Saharan Africa, Europe and Central Asia.

For more information about China National Space Administration (CNSA), visit: http://www.cnsa.gov.cn/n615709/cindex.html

Images, Video, Text, Credits: CNSA / CASC / CGWIC / ITN TV / AFP / Orbiter.ch.

Greetings, Orbiter.ch

NASA Discovers First Earth-Size Planets Beyond Our Solar System

NASA - Kepler Mission patch.

Dec. 20, 2011

NASA's Kepler mission has discovered the first Earth-size planets orbiting a sun-like star outside our solar system. The planets, called Kepler-20e and Kepler-20f, are too close to their star to be in the so-called habitable zone where liquid water could exist on a planet's surface, but they are the smallest exoplanets ever confirmed around a star like our sun.

The discovery marks the next important milestone in the ultimate search for planets like Earth. The new planets are thought to be rocky. Kepler-20e is slightly smaller than Venus, measuring 0.87 times the radius of Earth. Kepler-20f is slightly larger than Earth, measuring 1.03 times its radius. Both planets reside in a five-planet system called Kepler-20, approximately 1,000 light-years away in the constellation Lyra.

This artist's conception illustrates Kepler-20e. Image credit: NASA / Ames / JPL-Caltech

Kepler-20e orbits its parent star every 6.1 days and Kepler-20f every 19.6 days. These short orbital periods mean very hot, inhospitable worlds. Kepler-20f, at 800 degrees Fahrenheit, is similar to an average day on the planet Mercury. The surface temperature of Kepler-20e, at more than 1,400 degrees Fahrenheit, would melt glass.

“The primary goal of the Kepler mission is to find Earth-sized planets in the habitable zone," said Francois Fressin of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., lead author of a new study published in the journal Nature. "This discovery demonstrates for the first time that Earth-size planets exist around other stars, and that we are able to detect them.”

This artist's conception illustrates Kepler-20f. Image credit: NASA / Ames / JPL-Caltech

The Kepler-20 system includes three other planets that are larger than Earth but smaller than Neptune. Kepler-20b, the closest planet, Kepler-20c, the third planet, and Kepler-20d, the fifth planet, orbit their star every 3.7, 10.9 and 77.6 days. All five planets have orbits lying roughly within Mercury's orbit in our solar system. The host star belongs to the same G-type class as our sun, although it is slightly smaller and cooler.

The system has an unexpected arrangement. In our solar system, small, rocky worlds orbit close to the sun and large, gaseous worlds orbit farther out. In comparison, the planets of Kepler-20 are organized in alternating size: large, small, large, small and large.

"The Kepler data are showing us some planetary systems have arrangements of planets very different from that seen in our solar system," said Jack Lissauer, planetary scientist and Kepler science team member at NASA's Ames Research Center in Moffett Field, Calif. "The analysis of Kepler data continue to reveal new insights about the diversity of planets and planetary systems within our galaxy."

This chart compares artist's concept images of the first Earth-size planets found around a sun-like star to planets in our own solar system, Earth and Venus. Image credit: NASA / Ames / JPL-Caltech.

Scientists are not certain how the system evolved but they do not think the planets formed in their existing locations. They theorize the planets formed farther from their star and then migrated inward, likely through interactions with the disk of material from which they originated. This allowed the worlds to maintain their regular spacing despite alternating sizes.

The Kepler space telescope detects planets and planet candidates by measuring dips in the brightness of more than 150,000 stars to search for planets crossing in front, or transiting, their stars. The Kepler science team requires at least three transits to verify a signal as a planet.

This artist's animation flies through the Kepler-20 star system, where NASA's Kepler mission discovered the first Earth-size planets around a star beyond our own. Animation credit: NASA/Ames/JPL-Caltech.

The Kepler science team uses ground-based telescopes and the Spitzer Space Telescope to review observations on planet candidates the spacecraft finds. The star field Kepler observes in the constellations Cygnus and Lyra can be seen only from ground-based observatories in spring through early fall. The data from these other observations help determine which candidates can be validated as planets.

To validate Kepler-20e and Kepler-20f, astronomers used a computer program called Blender, which runs simulations to help rule out other astrophysical phenomena masquerading as a planet.

On Dec. 5 the team announced the discovery of Kepler-22b in the habitable zone of its parent star. It is likely to be too large to have a rocky surface. While Kepler-20e and Kepler-20f are Earth-size, they are too close to their parent star to have liquid water on the surface.

"In the cosmic game of hide and seek, finding planets with just the right size and just the right temperature seems only a matter of time," said Natalie Batalha, Kepler deputy science team lead and professor of astronomy and physics at San Jose State University. "We are on the edge of our seats knowing that Kepler's most anticipated discoveries are still to come."

For more information about the Kepler mission and to view the digital press kit, visit: http://www.nasa.gov/kepler

Images (mentioned), Video (mentioned), Text, Credit: NASA Ames Research Center, Michele Johnson.

Best regards, Orbiter.ch

Strangely slow pulsar discovered nestled in young supernova remnant

ESA - XMM Newton Mission patch.

20 Dec 2011

Astronomers have discovered a very slowly rotating X-ray pulsar still embedded in the remnant of the supernova that created it. This unusual object was detected on the outskirts of the Small Magellanic Cloud, a satellite galaxy of the Milky Way, using data from a number of telescopes, including ESA's XMM-Newton. A puzzling mismatch between the fairly young age of the supernova remnant and the slow rotation of the pulsar, which would normally indicate a much older object, raises interesting questions about the origin and evolution of pulsars.

Image above: The X-ray pulsar SXP 1062 embedded in the remnant of the supernova that created it.
Credit: ESA / XMM-Newton / L.Oskinova / M.Guerrero; CTIO / R.Gruendl / Y.H.Chu.

The spectacular supernova explosion that marks the end of a massive star's life also has an intriguing aftermath. On the one hand, the explosion sweeps up the surrounding interstellar material creating a supernova remnant that is often characterised by a distinctive bubble-like shape, on the other hand, the explosion also leaves behind a compact object – a neutron star or a black hole. Since supernova remnants shine only for a few tens of thousands of years before dispersing into the interstellar medium, not many compact objects have been detected while still enclosed in their expanding shell.

An international team of astronomers has now discovered one of these rarely observed pairs, consisting of a strongly magnetised, rotating neutron star – a pulsar – surrounded by the remains of the explosion that generated it.

The newly found pulsar, named SXP 1062, is located at the outskirts of the Small Magellanic Cloud (SMC), one of the satellite galaxies of the Milky Way. SXP 1062 is an X-ray pulsar, part of a binary system in which the compact object is accreting mass from a companion star, resulting in the emission of copious amounts of X-rays. The astronomers first detected the pulsar's X-ray emission using data from ESA's XMM-Newton as well as NASA's Chandra space-based observatories. A later study of optical images of the source and its surroundings revealed the bubble-shaped signature of the supernova remnant around the binary system.

"The most interesting aspect of this pulsar is possibly its extremely long period – 1062 seconds – which makes it one of the slowest pulsars on record," comments Lidia Oskinova from the Institute for Physics and Astronomy in Potsdam, Germany, coordinator of the team that analysed the X-ray data. Pulsars rotate quite rapidly in their early stages, with periods of only a fraction of a second, and then slow down gradually with age. "Slowly spinning pulsars are particularly difficult to detect. Only a few with periods longer than a thousand seconds have been observed to date," she adds.

To further investigate the binary system hosting this unusually slow pulsar, the team looked at the source at optical wavelengths, conducting follow-up observations with the European Southern Observatory's Very Large Telescope (VLT) and inspecting archival and newly acquired images from the Cerro Tololo Inter-American Observatory (CTIO).

"The VLT spectra confirm that the pulsar is accreting mass from a massive, hot, blue 'Be' star. The two bodies form a Be/X-ray binary, a class of X-ray binary that's very common in the SMC," explains Vincent Hénault-Brunet, PhD student at the Institute of Astronomy, University of Edinburgh, UK. Hénault-Brunet is the first author of a paper in which these results are reported. It will appear as a letter in the January 2012 issue of the Monthly Notices of the Royal Astronomical Society.

Image above: A star-forming region in the Wing of the Small Magellanic Cloud, with the X-ray pulsar SXP 1062 embedded in its supernova remnant (right) and the nebula N90, home to the star cluster NGC 602 (left). Credit: NASA / Chandra / ESA / XMM-Newton / CTIO.

The result relies on the combined power of a number of complementary observatories. "XMM-Newton's large effective area was instrumental in achieving high-sensitivity observations of the pulsar and the supernova remnant around it over a broad range of X-ray wavelengths," says Norbert Schartel, ESA's XMM-Newton Project Scientist. These data were combined with Chandra's, which probe the source at a higher angular resolution, albeit with lower sensitivity, to arrive at a comprehensive picture of the pulsar's X-ray emission.

The optical images, on the other hand, revealed the bubble-shaped nebula that harbours the binary system. This nebula appears to be the remnant of the supernova from which the pulsar itself originated. "Not many pulsars have been observed within their supernova remnant, and this is the first clear example of such a pair in the SMC," comments Hénault-Brunet.

Opportunities like this enable astronomers to study the complex relationship between the expanding remains of stellar explosions and the compact objects they leave behind. The case of SXP 1062 is particularly puzzling because of an apparent mismatch between the ages of the supernova remnant and that of the pulsar.

"Extremely slow rotation in pulsars normally points to old objects – something that doesn't quite agree in this case with the fairly young age of the supernova remnant, which ranges between 20,000 and 40,000 years," notes Oskinova.

The reason for the slow rotation of this pulsar remains a mystery: if it was born with a normal spin rate, how could it slow down to this extent in such a short time? Alternatively, was the pulsar born with a much slower rotation period than typically expected? Since the pulsar is located in the Wing of the SMC, an interesting peripheral region of this galaxy that is characterised by low density of stars, gas and dust, as well as by low metallicity, the environment may have played a role by affecting the properties of the pulsar's progenitor star before its demise in a supernova explosion.

The rich data set that this team of astronomers have gathered may yet contain an explanation for this peculiar case. "Our plan is to fully mine the X-ray data to study the system's variability in greater detail, and further study the optical spectra to investigate the properties of the companion star," says Oskinova. "We can't wait to see what the data tell us."

Notes for editors

The findings presented here report the discovery of a Be/X-ray binary system consisting of a pulsar, SXP 1062, and a companion 'Be' star, 2dFS 3831, located in the Wing of the Small Magellanic Cloud (SMC).

The study is based on complementary data from ESA's XMM-Newton and NASA's Chandra X-ray observatories. XMM-Newton's large effective area was key to high-sensitivity observations of the pulsar and supernova remnant over a broad range of X-ray wavelengths, while the Chandra data provide higher angular resolution, albeit at a lower sensitivity.

The Fibre Large Array Multi Element Spectrograph (FLAMES) on ESO's Very Large Telescope was used for follow-up optical spectroscopy. Archival images from the Magellanic Cloud Emission-Line Survey (MCELS) conducted at NOAO's Cerro Tololo Inter-American Observatory, as well as newly acquired images, were also used to study this portion of the sky in a number of emission lines: the H-alpha line of neutral hydrogen and two forbidden lines of oxygen [OIII] and sulphur [SII]. These lines trace emission from some of the elements produced during supernova explosions, making them excellent diagnostic tools for the study of supernova remnants.

An X-ray pulsar is one component of a binary system where the X-ray emission is produced by accretion of matter from the stellar companion onto the pulsar. Such pulsars generally have longer periods – typically between 1 and several hundred seconds – than the more common radio pulsars.

Neutron star X-ray binaries are classified into high-mass X-ray binaries (HMXB) and low-mass X-ray binaries (LMXB) depending on the mass of the companion star. HMXB are further divided into supergiant X-ray binaries (SGXB) and Be/X-ray binaries (BeXB). Be/X-ray binaries consist of a neutron star and a 'Be' companion star – a B-type star characterised by prominent hydrogen emission lines in its spectrum. Virtually all known Be/X-ray binaries harbour X-ray pulsars.

The SMC, a satellite galaxy of the Milky Way, is known to host about 50 HMXB – a surprisingly large population considering that its mass is only a few per cent of that of the Milky Way, in which about 70 HMXB are known to exist to date. All but one of the HMXB detected in the SMC are BeXB.

Images (mentioned), Text, Credits: ESA / XMM-Newton Project Scientist, Norbert Schartel / Institute for Astronomy, University of Edinburgh, Vincent Hénault-Brunet / Institute for Physics and Astronomy, University of Potsdam, Lidia Oskinova.

For more information about XMM Newton, visit: http://xmm.esac.esa.int/ and http://sci.esa.int/science-e/www/area/index.cfm?fareaid=23

Cheers, Orbiter.ch

SMOS versatility offers sea ice mapping

ESA - SMOS Mission logo.

20 December 2011

Laptev Sea ice thickness from SMOS

ESA’s SMOS mission is proving to be extremely versatile. Not only does this pioneering satellite offer crucial data on soil moisture and ocean salinity, but it can also map the thickness of ice floating in the polar seas.

The Soil Moisture and Ocean Salinity (SMOS) satellite carries an innovative passive microwave radiometer to capture images of ‘brightness temperature’. These images correspond to microwave radiation emitted from Earth’s surface and can be related to soil moisture and ocean salinity.

This information is essential for improving our understanding of the exchange processes between the atmosphere, land and oceans – Earth’s water cycle.

Although not a primary objective, it was suggested that the radiometer, which uses a wavelength of 21 cm (L-band), would also be able to detect sea ice, which is another important component of the water cycle.

In fact, an experiment campaign in 2007 over the Baltic Sea using an airborne version of the SMOS instrument confirmed that the mission had the potential to measure thin sea ice.

A group of scientists led by Prof. Kaleschke from the University of Hamburg’s Institute of Oceanography has now developed and refined a method to make this a reality – showing, indeed, that SMOS data can be used to map sea ice routinely. 

Sea ice in Laptev Sea

Moreover, the team has gone one step further so that the thickness of the sea ice can also be inferred. The information from SMOS is most reliable for ice that is thinner than 1 m.

As an example, the animation above shows how the sea ice in the Laptev Sea, which lies off northern Russia in the Arctic Ocean, advanced and thickened between 10 November and 10 December this year.

Prof. Kaleschke said, “Sea ice that is less than 50 cm thick is particularly important for weather and climate as it controls the exchange of heat between the ocean and atmosphere.

“This new information from SMOS will be very useful in monitoring ice as it grows in the winter and recedes in the spring.

“It will be used to investigate the exchange processes to improve our understanding of warming in the Arctic region.”

The information on sea-ice thickness is complementing that delivered by ESA’s CryoSat. Carrying a radar altimeter, CryoSat uses a different method of measuring sea ice – the height of the ice protruding above the water.

SMOS can offer daily coverage over the polar seas, while CryoSat provides higher spatial-resolution data and orbits very close to poles, thereby giving extra coverage.

The versatility of the SMOS mission appears to know no bounds. The mission has also demonstrated recently that it can offer new insight into the carbon and methane cycles by mapping soil as it freezes and thaws.

SMOS over ice

Susanne Mecklenburg, ESA’s SMOS Mission Manager, said, “We have the potential of realising some very exciting new products from SMOS.

“Thanks to the work of all the scientists, we are taking the mission to a new level and making a substantial contribution to Earth science and operational monitoring.”

Financed by ESA’s Support to Science Element programme, the methods for detecting and mapping sea ice will continue to be refined and applied to other parts of the polar oceans.

It is envisaged that these products will be released for applications such as numerical weather prediction, ship routing and operational oceanography.

Related links:

University of Hamburg–Institute of Oceanography: http://www.ifm.zmaw.de/

Alfred Wegener Institute: http://www.awi.de/en/home/

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

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

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

Credits: ESA / AOES Medialab / University of Hamburg Institute of Oceanography / Alfred Wegener Institute Sea Ice Physics.

Greetings, Orbiter.ch

ISS - Crew Conducts Human Research; Robonaut 2 Tests Resume

ISS - International Space Station patch / NASA - ROBONAUT (R-2) patch.

Dec. 19, 2011

The Expedition 30 crew members onboard the International Space Station stayed busy with an array of science and maintenance tasks while their counterparts on the ground relaxed ahead of a Dec. 21 launch.

Commander Dan Burbank worked with the long-running Integrated Cardiovascular experiment which studies cardiac atrophy, or heart shrinkage, that occurs during missions in space. He also set up gear that monitors radiation to understand its effects on the central nervous system for the ALTEA experiment (Anomalous Long Term Effects in Astronauts’ Central Nervous System).

After a fault message prevented tests on Robonaut 2 Thursday, ground controllers resolved the issue to proceed with its ongoing checkout. Burbank resumed work Friday with the first humanoid robot in space checking its joints and pressure sensors.

Image above: Commander Dan Burbank works with Robonaut 2 to test its joints and pressure sensors. Credit: NASA TV.

Robonaut 2 - A Dream Realized

The commander also performed some plumbing work inside the Waste and Hygiene Compartment. He wore a mask, goggles and gloves to avoid noxious treatment chemicals while removing a urine receptacle and filter.

Flight Engineers Anton Shkaplerov and Anatoly Ivanishin worked on several experiments throughout Friday, familiarized themselves with medical emergency procedures and maintained Russian systems.

ISS - International Space Station (Credit: NASA - STS-128)

Shkaplerov copied data acquired for the Sonocard experiment to a medical laptop computer. Sonocard studies contactless methods for monitoring a crew member’s health. He also studied how events such as vehicle dockings and reboosts affect the physical structure of the Russian side of the station for the Identification experiment.

Ivanishin worked on cargo transfers from the ISS Progress 45 resupply ship while updating the inventory management system. He also cleaned vents and air ducts.

All three crew members brushed up on their medical emergency response skills. They conducted a drill to familiarize themselves with medical gear locations and practiced communication and coordination skills.

Robonaut 2 - a dexterous, humanoid astronaut helper

New Expedition 30 Flight Engineers Oleg Kononenko, Don Pettit and Andre Kuipers relaxed Friday in their crew quarters at the Cosmonaut Hotel in Kazakhstan. Their launch aboard the Soyuz TMA-03M is scheduled for Dec. 21 at 8:16 a.m. EST.

Read more about Expedition 30: http://www.nasa.gov/mission_pages/station/expeditions/expedition30/index.html

Send a holiday postcard to the station crew: http://www.nasa.gov/externalflash/postcard/

Read more about the Dragon flight: http://www.nasa.gov/home/hqnews/2011/dec/HQ_11-413_SpaceX_ISS_Flight.html

Images, Video, Text, Credit: NASA / JPL / GM / NASA TV / Youtube.

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