samedi 1 octobre 2016
ISS - Expedition 49 Mission patch.
October 1, 2016
BEAM, the new expandable module attached to the International Space Station, was opened up today for tests and equipment checks. The Expedition 49 crew also explored eating right in space, adapting to new technology and studied a variety of other life science and physics research.
Flight Engineer Kate Rubins opened up and entered the Bigelow Expandable Activity Module on September 29, 2016. She temporarily installed gear inside BEAM for a test to measure the loads and vibrations the module experiences. Rubins started her day with a performance test on a mobile tablet device then videotaped her observations of the living conditions aboard the space station.
Image above: BEAM, the Bigelow Expandable Activity Module, is pictured installed on the Tranquility module and expanded to its full-size volume. Image Credit: NASA.
Japanese astronaut Takuya Onishi started an 11-day run today to document his meals while wearing a monitor that will take water samples and measure his breathing. The ENERGY experiment will help doctor’s understand metabolism in space and ensure astronauts are properly nourished to maintain the energy required for a long-term mission. Onishi is also continuing to set up the Group Combustion fuel burning study and checked for pressure leaks in the experiment gear.
In the Russian side of the orbital laboratory, Commander Anatoly Ivanishin resumed studying charged particle systems trapped in a magnetic field. He also participated in a pair of Earth photography experiments observing how natural and man-made disasters including industrial activities affect the land and sea.
Expedition 49 Trio Wrapping Up Busy September
September was a busy month on the International Space Station filled with a wide variety of space research, a spacewalk, a crew departure and a test of the new BEAM module. One science highlight this month includes a new experiment that may improve how medicine works.
This week, astronaut Kate Rubins tested the endurance of the new Bigelow Expandable Aerospace Module in the vacuum of space. She also explored how solids dissolve in liquids to help the medicine industry design better performing drugs for humans on Earth and astronauts in space.
Image above: Astronaut Kate Rubins works on an experiment inside the Microgravity Science Glovebox. Image Credit: NASA.
A new fuel burning study is about to start soon after Japanese astronaut Takuya Onishi completes the installation of the Group Combustion experiment. Results from the fire research could help engineers design advanced rocket engines and industrial furnaces. Onishi is also documenting his meals over the next few days for the ENERGY study. Onishi’s meal data in conjunction with his water and breath samples will help scientists understand the nutritional requirements necessary for long-term space missions.
Cosmonaut Anatoly Ivanishin, who took command of Expedition 49 on Sept. 6, has been working on the continuous upkeep of the Russian segment of the space station. The veteran cosmonaut has been preparing a Progress resupply ship for its Oct. 14 undocking. Some of the numerous Russian science experiments Ivanishin has been conducting have been observing the condition of the Earth and exploring human research.
Bigelow Expandable Activity Module: http://www.nasa.gov/mission_pages/station/research/experiments/1804.html
ENERGY experiment: http://www.nasa.gov/mission_pages/station/research/experiments/397.html
Group Combustion fuel burning study: http://www.nasa.gov/mission_pages/station/research/experiments/1077.html
Charged particle systems study: http://www.energia.ru/en/iss/researches/popular/02.html
Natural and man-made disasters: http://www.energia.ru/en/iss/researches/study/09.html
Industrial activities: http://www.energia.ru/en/iss/researches/study/10.html
Solids dissolve in liquids: http://www.nasa.gov/mission_pages/station/research/experiments/2275.html
Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html
International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html
Images (mentioned), Text, Credits: NASA/Mark Garcia.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 05:29
vendredi 30 septembre 2016
NOAA / NASA - GOES Satellite Mission logo / NASA - Suomi NPP Satellite logo.
Matthew (Atlantic Ocean)
Image above: NOAA's GOES-East satellite captured a visible-light image of Hurricane Matthew on Sept. 30, 2016, at 1:45 p.m. EDT as it was strengthening into a major hurricane. Image Credits: NASA/NOAA GOES Project.
NOAA's GOES-East satellite captured a visible-light image of Hurricane Matthew on Sept. 30 at 1:45 p.m. EDT as it was strengthening into a major hurricane.
At NASA's Goddard Space Flight Center in Greenbelt, Maryland, the NASA/NOAA GOES Project used data from NOAA's GOES-East satellite to create an image of the Caribbean Sea's major hurricane. The eye was visible in satellite imagery.
At 2 p.m. EDT a tropical storm warning is in effect for the Colombia-Venezuela border to Riohacha.
Data from a NOAA Hurricane Hunter aircraft indicate that maximum sustained winds have increased to near 120 mph (195 kph) with higher gusts. Matthew is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. Little change in strength is forecast during the next 48 hours.
The eye of Hurricane Matthew was located near 13.6 degrees north latitude and 71.3 degrees west longitude. Matthew is moving toward the west-southwest near 12 mph (19 kph). A westward motion at a slower forward speed is expected later today and tonight. A turn toward the west-northwest is forecast by Saturday night, followed by a turn toward the northwest by early Sunday. On the forecast track, the center of Matthew will pass north of the Guajira Peninsula this afternoon and tonight and remain over the central Caribbean Sea through early Sunday.
Image above: On Sept. 29, 2016, at 1 p.m. EDT (17:00 UTC) NASA-NOAA's Suomi NPP satellite captured this visible image of then-Tropical Storm Matthew in the Caribbean Sea. Image Credits: NOAA/NASA Goddard MODIS Rapid Response Team.
On Sept. 29 at 1 p.m. EDT (17:00 UTC) the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the NASA-NOAA Suomi NPP satellite captured a visible image of Tropical Storm Matthew south of Puerto Rico, and moving west in the Caribbean Sea.
On Sept. 30 at 8 a.m. EDT, NOAA's National Hurricane Center (NHC) noted that a tropical storm watch was in effect for Aruba and the Colombia/Venezuela border to Riohacha. A tropical storm watch means that tropical storm conditions are possible within the watch area, in this case within the next 24 to 36 hours.
At NASA's Goddard Space Flight Center in Greenbelt, Maryland, the NASA/NOAA GOES Project combined infrared and visible imagery from NOAA's GOES-East satellite into an animation of Matthew. The animation of imagery from Sept. 27 to Sept. 30 shows Tropical Storm Matthew move into the Caribbean Sea, where it became a hurricane.
Matthew Becomes a Hurricane in Caribbean
Video above: This animation of NOAA's GOES-East satellite imagery from Sept. 27 to Sept. 30, 2016, shows Tropical Storm Matthew move into the Caribbean Sea where it became a hurricane. Image Credits: NASA/NOAA GOES Project.
At 8 a.m. EDT (1200 UTC) on Sept. 30 the center of Hurricane Matthew was located by an Air Force Reserve Hurricane Hunter aircraft near 13.8 degrees north latitude and 70.3 degrees west longitude. That's about 130 miles (210 km) northeast of Punta Gallinas, Colombia, and about 520 miles (840 km) east-southeast of Kingston, Jamaica.
Matthew was moving toward the west-southwest near 14 mph (22 kph). NHC said a turn toward the west is expected later today, and this westward motion with a decrease in forward speed are forecast through Saturday. A turn toward the northwest is expected Saturday night or Sunday, Oct. 2. The latest minimum central pressure reported by the aircraft was 971 millibars.
NHC noted that data from the aircraft indicate that maximum sustained winds have increased to near 105 mph (165 km/h) with higher gusts. Additional strengthening is forecast during the next 48 hours, and Matthew could become a major hurricane later today or tonight, Sept. 30.
NHC said interests elsewhere along the coasts of Venezuela and Colombia should monitor the progress of Matthew. Interests in Jamaica, Hispaniola, and eastern Cuba should also monitor the progress of Matthew. A hurricane watch may be required for Jamaica later today.
NASA-NOAA Suomi NPP satellite: http://www.nasa.gov/mission_pages/NPP/main/index.html
GOES (Geostationary Environmental Operational Satellites): http://www.nasa.gov/goes/
For hurricane effects, visit the NHC website: http://www.nhc.noaa.gov.
Images (mentioned), Video (mentioned), Text, Credits: NASA's Goddard Space Flight Center, by Rob Gutro.
Publié par Orbiter.ch à 15:20
NASA - Hubble Space Telescope patch.
Sept. 30, 2016
This shining disk of a spiral galaxy sits approximately 25 million light-years away from Earth in the constellation of Sculptor. Named NGC 24, the galaxy was discovered by British astronomer William Herschel in 1785, and measures some 40,000 light-years across.
This picture was taken using the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys, known as ACS for short. It shows NGC 24 in detail, highlighting the blue bursts (young stars), dark lanes (cosmic dust), and red bubbles (hydrogen gas) of material peppered throughout the galaxy’s spiral arms. Numerous distant galaxies can also been seen hovering around NGC 24’s perimeter.
However, there may be more to this picture than first meets the eye. Astronomers suspect that spiral galaxies like NGC 24 and the Milky Way are surrounded by, and contained within, extended haloes of dark matter. Dark matter is a mysterious substance that cannot be seen; instead, it reveals itself via its gravitational interactions with surrounding material. Its existence was originally proposed to explain why the outer parts of galaxies, including our own, rotate unexpectedly fast, but it is thought to also play an essential role in a galaxy’s formation and evolution. Most of NGC 24’s mass — a whopping 80 percent — is thought to be held within such a dark halo.
Hubble and the sunrise over Earth
For more information about the Hubble Space Telescope, visit:
Image, Video, Credits: NASA/ESA/Text, Credits: European Space Agency/NASA/Karl Hille.
Publié par Orbiter.ch à 15:01
ESA - Rosetta Mission patch.
30 September 2016
ESA’s historic Rosetta mission has concluded as planned, with the controlled impact onto the comet it had been investigating for more than two years.
Confirmation of the end of the mission arrived at ESA’s control centre in Darmstadt, Germany at 11:19 GMT (13:19 CEST) with the loss of Rosetta’s signal upon impact.
Rosetta carried out its final manoeuvre last night at 20:50 GMT (22:50 CEST), setting it on a collision course with the comet from an altitude of about 19 km. Rosetta had targeted a region on the small lobe of Comet 67P/Churyumov–Gerasimenko, close to a region of active pits in the Ma’at region.
Comet landing site
The descent gave Rosetta the opportunity to study the comet’s gas, dust and plasma environment very close to its surface, as well as take very high-resolution images.
Pits are of particular interest because they play an important role in the comet’s activity. They also provide a unique window into its internal building blocks.
The information collected on the descent to this fascinating region was returned to Earth before the impact. It is now no longer possible to communicate with the spacecraft.
“Rosetta has entered the history books once again,” says Johann-Dietrich Wörner, ESA’s Director General. “Today we celebrate the success of a game-changing mission, one that has surpassed all our dreams and expectations, and one that continues ESA’s legacy of ‘firsts’ at comets.”
Comet from 51 m – wide-angle camera
“Thanks to a huge international, decades-long endeavour, we have achieved our mission to take a world-class science laboratory to a comet to study its evolution over time, something that no other comet-chasing mission has attempted,” notes Alvaro Giménez, ESA’s Director of Science.
“Rosetta was on the drawing board even before ESA’s first deep-space mission, Giotto, had taken the first image of a comet nucleus as it flew past Halley in 1986.
“The mission has spanned entire careers, and the data returned will keep generations of scientist busy for decades to come.”
“As well as being a scientific and technical triumph, the amazing journey of Rosetta and its lander Philae also captured the world’s imagination, engaging new audiences far beyond the science community. It has been exciting to have everyone along for the ride,” adds Mark McCaughrean, ESA’s senior science advisor.
Since launch in 2004, Rosetta is now in its sixth orbit around the Sun. Its nearly 8 billion-kilometre journey included three Earth flybys and one at Mars, and two asteroid encounters.
The craft endured 31 months in deep-space hibernation on the most distant leg of its journey, before waking up in January 2014 and finally arriving at the comet in August 2014.
Comet landing sites in context
After becoming the first spacecraft to orbit a comet, and the first to deploy a lander, Philae, in November 2014, Rosetta continued to monitor the comet’s evolution during their closest approach to the Sun and beyond.
“We’ve operated in the harsh environment of the comet for 786 days, made a number of dramatic flybys close to its surface, survived several unexpected outbursts from the comet, and recovered from two spacecraft ‘safe modes’,” says operations manager Sylvain Lodiot.
“The operations in this final phase have challenged us more than ever before, but it’s a fitting end to Rosetta’s incredible adventure to follow its lander down to the comet.”
The decision to end the mission on the surface is a result of Rosetta and the comet heading out beyond the orbit of Jupiter again. Further from the Sun than Rosetta has ever journeyed before, there would be little power to operate the craft.
Mission operators were also faced with an imminent month-long period when the Sun is close to the line-of-sight between Earth and Rosetta, meaning communications with the craft would have become increasingly more difficult.
“With the decision to take Rosetta down to the comet’s surface, we boosted the scientific return of the mission through this last, once-in-a-lifetime operation,” says mission manager Patrick Martin.
Rosetta’s final path
Many surprising discoveries have already been made during the mission, not least the curious shape of the comet that became apparent during Rosetta’s approach in July and August 2014. Scientists now believe that the comet’s two lobes formed independently, joining in a low-speed collision in the early days of the Solar System.
Long-term monitoring has also shown just how important the comet’s shape is in influencing its seasons, in moving dust across its surface, and in explaining the variations measured in the density and composition of the coma, the comet’s ‘atmosphere’.
Visualising Rosetta's descent
Some of the most unexpected and important results are linked to the gases streaming from the comet’s nucleus, including the discovery of molecular oxygen and nitrogen, and water with a different ‘flavour’ to that in Earth’s oceans.
Together, these results point to the comet being born in a very cold region of the protoplanetary nebula when the Solar System was still forming more than 4.5 billion years ago.
While it seems that the impact of comets like Rosetta’s may not have delivered as much of Earth’s water as previously thought, another much anticipated question was whether they could have brought ingredients regarded as crucial for the origin of life.
Rosetta did not disappoint, detecting the amino acid glycine, which is commonly found in proteins, and phosphorus, a key component of DNA and cell membranes. Numerous organic compounds were also detected ¬by Rosetta from orbit, and also by Philae in situ on the surface.
“It’s a bittersweet ending, but in the end the mechanics of the Solar System were simply against us: Rosetta’s destiny was set a long time ago. But its superb achievements will now remain for posterity and be used by the next generation of young scientists and engineers around the world.”
While the operational side of the mission has finished today, the science analysis will continue for many years to come.
Overall, the results delivered by Rosetta so far paint comets as ancient leftovers of early Solar System formation, rather than fragments of collisions between larger bodies later on, giving an unparalleled insight into what the building blocks of the planets may have looked like 4.6 billion years ago.
“Just as the Rosetta Stone after which this mission was named was pivotal in understanding ancient language and history, the vast treasure trove of Rosetta spacecraft data is changing our view on how comets and the Solar System formed,” says project scientist Matt Taylor.
“Inevitably, we now have new mysteries to solve. The comet hasn’t given up all of its secrets yet, and there are sure to be many surprises hidden in this incredible archive. So don’t go anywhere yet – we’re only just beginning.”
Notes for Editors:
Rosetta was an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander was provided by a consortium led by DLR, MPS, CNES and ASI. Rosetta was the first mission in history to rendezvous with a comet and escort it as they orbited the Sun together. It was also the first to deploy a lander to a comet’s surface, and later end its mission in a controlled impact on the comet.
Comets are time capsules containing primitive material left over from the epoch when the Sun and its planets formed. By studying the gas, dust and structure of the nucleus and organic materials associated with the comet, via both remote and in situ observations, the Rosetta mission is a key to unlocking the history and evolution of our Solar System.
Comet viewer tool: http://sci.esa.int/comet-viewer/
For more information about Rosetta mission, visit: http://www.esa.int/Our_Activities/Space_Science/Rosetta
Rosetta overview: http://www.esa.int/Our_Activities/Space_Science/Rosetta_overview
Rosetta in depth: http://sci.esa.int/rosetta
Images, Videos, Text, Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA/CIVA: ESA/Rosetta/Philae/CIVA; NAVCAM: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0; OSIRIS: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA; ROLIS: ESA/Rosetta/Philae/ROLIS/DLR/ATG medialab.
Best regards, Orbiter.ch
Publié par Orbiter.ch à 06:24
jeudi 29 septembre 2016
NASA - Fermi Gamma-ray Space Telescope logo.
Sept. 29, 2016
Using data from NASA's Fermi Gamma-ray Space Telescope and other facilities, an international team of scientists has found the first gamma-ray binary in another galaxy and the most luminous one ever seen. The dual-star system, dubbed LMC P3, contains a massive star and a crushed stellar core that interact to produce a cyclic flood of gamma rays, the highest-energy form of light.
"Fermi has detected only five of these systems in our own galaxy, so finding one so luminous and distant is quite exciting," said lead researcher Robin Corbet at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Gamma-ray binaries are prized because the gamma-ray output changes significantly during each orbit and sometimes over longer time scales. This variation lets us study many of the emission processes common to other gamma-ray sources in unique detail."
These rare systems contain either a neutron star or a black hole and radiate most of their energy in the form of gamma rays. Remarkably, LMC P3 is the most luminous such system known in gamma rays, X-rays, radio waves and visible light, and it's only the second one discovered with Fermi.
NASA's Fermi Finds Record-breaking Binary Star
Video above: Dive into the Large Magellanic Cloud and see a visualization of LMC P3, an extraordinary gamma-ray binary system discovered by NASA's Fermi Gamma-ray Space Telescope. Video Credits: NASA's Goddard Space Flight Center/Scott Wiessinger, producer.
A paper describing the discovery will appear in the Oct. 1 issue of The Astrophysical Journal and is now available online: http://iopscience.iop.org/article/10.3847/0004-637X/829/2/105
LMC P3 lies within the expanding debris of a supernova explosion located in the Large Magellanic Cloud (LMC), a small nearby galaxy about 163,000 light-years away. In 2012, scientists using NASA's Chandra X-ray Observatory found a strong X-ray source within the supernova remnant and showed that it was orbiting a hot, young star many times the sun's mass. The researchers concluded the compact object was either a neutron star or a black hole and classified the system as a high-mass X-ray binary (HMXB).
In 2015, Corbet's team began looking for new gamma-ray binaries in Fermi data by searching for the periodic changes characteristic of these systems. The scientists discovered a 10.3-day cyclic change centered near one of several gamma-ray point sources recently identified in the LMC. One of them, called P3, was not linked to objects seen at any other wavelengths but was located near the HMXB. Were they the same object?
Image above: Observations from Fermi's Large Area Telescope (magenta line) show that gamma rays from LMC P3 rise and fall over the course of 10.3 days. The companion is thought to be a neutron star. Illustrations across the top show how the changing position of the neutron star relates to the gamma-ray cycle. Image Credits: NASA's Goddard Space Flight Center.
To find out, Corbet's team observed the binary in X-rays using NASA's Swift satellite, at radio wavelengths with the Australia Telescope Compact Array near Narrabri and in visible light using the 4.1-meter Southern Astrophysical Research Telescope on Cerro Pachón in Chile and the 1.9-meter telescope at the South African Astronomical Observatory near Cape Town.
The Swift observations clearly reveal the same 10.3-day emission cycle seen in gamma rays by Fermi. They also indicate that the brightest X-ray emission occurs opposite the gamma-ray peak, so when one reaches maximum the other is at minimum. Radio data exhibit the same period and out-of-phase relationship with the gamma-ray peak, confirming that LMC P3 is indeed the same system investigated by Chandra.
"The optical observations show changes due to binary orbital motion, but because we don't know how the orbit is tilted into our line of sight, we can only estimate the individual masses," said team member Jay Strader, an astrophysicist at Michigan State University in East Lansing. "The star is between 25 and 40 times the sun's mass, and if we're viewing the system at an angle midway between face-on and edge-on, which seems most likely, its companion is a neutron star about twice the sun's mass." If, however, we view the binary nearly face-on, then the companion must be significantly more massive and a black hole.
Image above: LMC P3 (circled) is located in a supernova remnant called DEM L241 in the Large Magellanic Cloud, a small galaxy about 163,000 light-years away. The system is the first gamma-ray binary discovered in another galaxy and is the most luminous known in gamma rays, X-rays, radio waves and visible light. Image Credit: NASA.
Both objects form when a massive star runs out of fuel, collapses under its own weight and explodes as a supernova. The star's crushed core may become a neutron star, with the mass of half a million Earths squeezed into a ball no larger than Washington, D.C. Or it may be further compacted into a black hole, with a gravitational field so strong not even light can escape it.
The surface of the star at the heart of LMC P3 has a temperature exceeding 60,000 degrees Fahrenheit (33,000 degrees Celsius), or more than six times hotter than the sun's. The star is so luminous that pressure from the light it emits actually drives material from the surface, creating particle outflows with speeds of several million miles an hour.
In gamma-ray binaries, the compact companion is thought to produce a "wind" of its own, one consisting of electrons accelerated to near the speed of light. The interacting outflows produce X-rays and radio waves throughout the orbit, but these emissions are detected most strongly when the compact companion travels along the part of its orbit closest to Earth.
Through a different mechanism, the electron wind also emits gamma rays. When light from the star collides with high-energy electrons, it receives a boost to gamma-ray levels. Called inverse Compton scattering, this process produces more gamma rays when the compact companion passes near the star on the far side of its orbit as seen from our perspective.
Prior to Fermi's launch, gamma-ray binaries were expected to be more numerous than they've turned out to be. Hundreds of HMXBs are cataloged, and these systems are thought to have originated as gamma-ray binaries following the supernova that formed the compact object.
"It is certainly a surprise to detect a gamma-ray binary in another galaxy before we find more of them in our own," said Guillaume Dubus, a team member at the Institute of Planetology and Astrophysics of Grenoble in France. "One possibility is that the gamma-ray binaries Fermi has found are rare cases where a supernova formed a neutron star with exceptionally rapid spin, which would enhance how it produces accelerated particles and gamma rays."
NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy and with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.
Fermi Gamma-Ray Space Telescope: http://www.nasa.gov/mission_pages/GLAST/main/index.html
NASA's Chandra X-ray Observatory: https://www.nasa.gov/mission_pages/chandra/main/index.html
NASA's Swift satellite: https://www.nasa.gov/mission_pages/swift/main
Southern Astrophysical Research Telescope: http://www.ctio.noao.edu/soar/
South African Astronomical Observatory: http://www.saao.ac.za/
Images (mentioned), Video (mentioned), Text, Credits: NASA's Goddard Space Flight Center, by Francis Reddy/Rob Garner.
Publié par Orbiter.ch à 16:09
NASA - Mars Science Laboratory (MSL) logo.
Sept. 29, 2016
Image above: This low-angle self-portrait of NASA's Curiosity Mars rover shows the vehicle at the site from which it reached down to drill into a rock target called "Buckskin." The MAHLI camera on Curiosity's robotic arm took multiple images on Aug. 5, 2015, that were stitched together into this selfie. Image Credits: NASA/JPL-Caltech/MSSS.
NASA's Curiosity rover has found evidence that chemistry in the surface material on Mars contributed dynamically to the makeup of its atmosphere over time. It’s another clue that the history of the Red Planet’s atmosphere is more complex and interesting than a simple legacy of loss.
The findings come from the rover’s Sample Analysis at Mars, or SAM, instrument suite, which studied the gases xenon and krypton in Mars’ atmosphere. The two gases can be used as tracers to help scientists investigate the evolution and erosion of the Martian atmosphere. A lot of information about xenon and krypton in Mars’ atmosphere came from analyses of Martian meteorites and measurements made by the Viking mission.
Image above: Chemistry that takes place in the surface material on Mars can explain why particular xenon (Xe) and krypton (Kr) isotopes are more abundant in the Martian atmosphere than expected. The isotopes – variants that have different numbers of neutrons – are formed in the loose rocks and material that make up the regolith. The chemistry begins when cosmic rays penetrate into the surface material. If the cosmic rays strike an atom of barium (Ba), the barium can lose one or more of its neutrons (n0). Atoms of xenon can pick up some of those neutrons – a process called neutron capture – to form the isotopes xenon-124 and xenon-126. In the same way, atoms of bromine (Br) can lose some of their neutrons to krypton, leading to the formation of krypton-80 and krypton-82 isotopes. These isotopes can enter the atmosphere when the regolith is disturbed by impacts and abrasion and gas escapes from the regolith. Image Credits: NASA's Goddard Space Flight Center.
“What we found is that earlier studies of xenon and krypton only told part of the story,” said Pamela Conrad, lead author of the report and SAM’s deputy principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “SAM is now giving us the first complete in situ benchmark against which to compare meteorite measurements.”
Of particular interest to scientists are the ratios of certain isotopes – or chemical variants – of xenon and krypton. The SAM team ran a series of first-of-a-kind experiments to measure all the isotopes of xenon and krypton in the Martian atmosphere. The experiments are described in a paper published in Earth and Planetary Science Letters.
The team’s method is called static mass spectrometry, and it’s good for detecting gases or isotopes that are present only in trace amounts. Although static mass spectrometry isn’t a new technique, its use on the surface of another planet is something only SAM has done.
Overall, the analysis agreed with earlier studies, but some isotope ratios were a bit different than expected. When working on an explanation for those subtle but important differences, the researchers realized that neutrons might have gotten transferred from one chemical element to another within the surface material on Mars. The process is called neutron capture, and it would explain why a few selected isotopes were more abundant than previously thought possible.
In particular, it looks as if some of the barium surrendered neutrons that got picked up by xenon to produce higher-than-expected levels of the isotopes xenon-124 and 126. Likewise, bromine might have surrendered some of its neutrons to produce unusual levels of krypton-80 and krypton-82.
Image above: The Sample Analysis at Mars instrument suite on NASA’s Curiosity rover. Image Credits: NASA's Goddard Space Flight Center.
These isotopes could have been released into the atmosphere by impacts on the surface and by gas escaping from the regolith, which is the soil and broken rocks of the surface.
“SAM’s measurements provide evidence of a really interesting process in which the rock and unconsolidated material at the planet’s surface have contributed to the xenon and krypton isotopic composition of the atmosphere in a dynamic way,” said Conrad.
The atmospheres of Earth and Mars exhibit very different patterns of xenon and krypton isotopes, particularly for xenon-129. Mars has much more of it in the atmosphere than does Earth.
“The unique capability to measure in situ the six and nine different isotopes of krypton and xenon allows scientists to delve into the complex interactions between the Martian atmosphere and crust,” said Michael Meyer, lead scientist for the Mars Exploration Program at NASA Headquarters in Washington. “Discovering these interactions through time allows us to gain a greater understanding of planetary evolution.”
NASA’s Mars Science Laboratory Project is using Curiosity to determine if life was possible on Mars and study major changes in Martian environmental conditions. NASA studies Mars to learn more about our own planet, and in preparation for future human missions to Mars. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the project for NASA’s Science Mission Directorate in Washington.
For more information about SAM, visit: http://ssed.gsfc.nasa.gov/sam/
SAM experiment data are archived in the Planetary Data System, online at: http://pds.nasa.gov/
For more information about Curiosity, visit: http://www.nasa.gov/msl
The research paper is available at: http://dx.doi.org/10.1016/j.epsl.2016.08.028
Images (mentioned), Text, Credits: NASA’s Goddard Space Flight Center, written by Elizabeth Zubritsky/JPL/Guy Webster/Karl Hille.
Publié par Orbiter.ch à 15:52
ALMA - Atacama Large Millimeter/submillimeter Array logo.
29 September 2016
The first of its kind to be found outside the Milky Way
Artist's impression of the hot molecular core discovered in the Large Magellanic Cloud
A hot and dense mass of complex molecules, cocooning a newborn star, has been discovered by a Japanese team of astronomers using ALMA. This unique hot molecular core is the first of its kind to have been detected outside the Milky Way galaxy. It has a very different molecular composition from similar objects in our own galaxy — a tantalising hint that the chemistry taking place across the Universe could be much more diverse than expected.
A team of Japanese researchers have used the power of the Atacama Large Millimeter/submillimeter Array (ALMA) to observe a massive star known as ST11  in our neighbouring dwarf galaxy, the Large Magellanic Cloud (LMC). Emission from a number of molecular gases was detected. These indicated that the team had discovered a concentrated region of comparatively hot and dense molecular gas around the newly ignited star ST11. This was evidence that they had found something never before seen outside of the Milky Way — a hot molecular core .
Takashi Shimonishi, an astronomer at Tohoku University, Japan, and the paper's lead author enthused: "This is the first detection of an extragalactic hot molecular core, and it demonstrates the great capability of new generation telescopes to study astrochemical phenomena beyond the Milky Way."
The ALMA observations revealed that this newly discovered core in the LMC has a very different composition to similar objects found in the Milky Way. The most prominent chemical signatures in the LMC core include familiar molecules such as sulfur dioxide, nitric oxide, and formaldehyde — alongside the ubiquitous dust. But several organic compounds, including methanol (the simplest alcohol molecule), had remarkably low abundance in the newly detected hot molecular core. In contrast, cores in the Milky Way have been observed to contain a wide assortment of complex organic molecules, including methanol and ethanol.
ALMA results and the region seen in infrared light
Takashi Shimonishi explains: “The observations suggest that the molecular compositions of materials that form stars and planets are much more diverse than we expected.”
The LMC has a low abundance of elements other than hydrogen or helium . The research team suggests that this very different galactic environment has affected the molecule-forming processes taking place surrounding the newborn star ST11. This could account for the observed differences in chemical compositions.
It is not yet clear if the large, complex molecules detected in the Milky Way exist in hot molecular cores in other galaxies. Complex organic molecules are of very special interest because some are connected to prebiotic molecules formed in space. This newly discovered object in one of our nearest galactic neighbours is an excellent target to help astronomers address this issue. It also raises another question: how could the chemical diversity of galaxies affect the development of extragalactic life?
 ST11’s full name is 2MASS J05264658-6848469. This catchily-named young massive star is defined as a Young Stellar Object. Although it currently appears to be a single star, it is possible that it will prove to be a tight cluster of stars, or possibly a multiple star system. It was the target of the science team’s observations and their results led them to realise that ST11 is enveloped by a hot molecular core.
 Hot molecular cores must be: (relatively) small, with a diameter of less than 0.3 light-years; have a density over a thousand billion (1012) molecules per cubic metre (far lower than the Earth's atmosphere, but high for an interstellar environment); warm in temperature, at over –173 degrees Celsius. This makes them at least 80 degrees Celsius warmer than a standard molecular cloud, despite being of similar density. These hot cores form early on in the evolution of massive stars and they play a key role in the formation of complex chemicals in space.
 The nuclear fusion reactions that take place when a star has stopped fusing hydrogen to helium generate heavier elements. These heavier elements get blasted into space when massive dying stars explode as supernovae. Therefore, as our Universe has aged, the abundance of heavier elements has increased. Thanks to its low abundance of heavier elements, the LMC provides insight into the chemical processes that were taking place in the earlier Universe.
This research was presented in a paper published in the Astrophysical Journal on August 9, 2016, entitled The Detection of a Hot Molecular Core in the Large Magellanic Cloud with ALMA: http://dx.doi.org/10.3847/0004-637X/827/1/72
The team is composed of Takashi Shimonishi (Frontier Research Institute for Interdisciplinary Sciences & Astronomical Institute, Tohoku University, Japan), Takashi Onaka (Department of Astronomy, The University of Tokyo, Japan), Akiko Kawamura (National Astronomical Observatory of Japan, Japan) and Yuri Aikawa (Center for Computational Sciences, The University of Tsukuba, Japan)
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).
ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
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 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. 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 a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.
Research paper: http://www.eso.org/public/archives/releases/sciencepapers/eso1634/eso1634a.pdf
Photos of ALMA: http://www.eso.org/public/images/archive/category/alma/
Atacama Large Millimeter/submillimeter Array (ALMA): http://www.eso.org/public/teles-instr/alma/
Images, Text, Credits: ESO/M. Kornmesser; NASA, ESA, and S. Beckwith (STScI) and the HUDF Team; NASA/ESA and the Hubble Heritage Team (AURA/STScI)/HEI/FRIS/Tohoku University/T. Shimonishi/Tohoku University, ALMA (ESO/NAOJ/NRAO).
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Publié par Orbiter.ch à 12:55