vendredi 14 août 2015

Progress M-26M has successfully undocked from the ISS











ROSCOSMOS - Russian Vehicles patch.

14/08/2015

Progress-M space cargo undocking ISS. Image Credit: NASA TV

In accordance with the flight of the International Space Station on August 14, 2015 in 13 hours 18 minutes Moscow time, the command was given to undock cargo spacecraft Progress M-26M from the service module of the Russian segment of the ISS (13:19 - undocking). After removal of the ship to a safe distance from the station, Mission Control Center specialists have started FSUE TsNIIMash controlled reduction of the spacecraft from orbit.

The Progress M-26M was docked on ISS on February 17, 2015. After completing the main task of delivering needed to maintain the functioning of the station life systems for the crew (new filters and parts, food, water), was used for 12 orbit correction at providing ballistic flight station.

video
Russian Space Station Supply Ship Departs ISS

Video Credit: NASA TV.

According to the calculations of experts providing ballistic flight service station, engine of cargo ship Progress M-26M to be deorbited today in 16 hours 28 minutes Moscow time and, having worked on the braking pulse position, the ship was oriented to the descent to Earth.

At 17 hours 17 minutes Moscow Time fireproof structural elements of the ship fall in the estimated area of ​​non-navigational area of ​​the Pacific Ocean.

In accordance with the schedule of flights to the International Space Station, is scheduled for August 17 launch of the Japanese cargo spacecraft HTV-5 after 4 days is expected to dock with the ISS. Progress M-29M is scheduled for October 1, 2015.

ROSCOSMOS Press Release: http://www.federalspace.ru/21639/ and http://www.federalspace.ru/21641/

Image (mentioned), Video (mentioned), Text, Credits: Press Service of the Russian Federal Space Agency (ROSCOSMOS)/Orbiter.ch Aerospace.

Greetings, Orbiter.ch

How Does NASA Study Hurricanes?












NASA patch.

Aug. 14, 2015

Hurricanes are the most powerful weather event on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

The National Oceanic and Atmospheric Administration and the National Hurricane Center (NHC) use a variety of tools to predict these storms’ paths. These scientists need a wealth of data to accurately forecast hurricanes. NASA satellites, computer modeling, instruments, aircraft and field missions contribute to this mix of information to give scientists a better understanding of these storms.


Image above: This visible image of Hurricane Katrina was taken on August 29 at 05:16 UTC (1:16 a.m. EDT) by the MODIS instrument that flies aboard NASA's Aqua satellite as it approached landfall in Louisiana. Image Credits: NASA Goddard MODIS Rapid Response Team.

NASA's Research Role

NASA’s role as a research agency is to bring new types of observational capabilities and analytical tools to learn about the fundamental processes that drive hurricanes and work to help incorporate that data into forecasts. NASA collaborates with its interagency partners so that the nation benefits from our respective capabilities.

“Before we had satellites and aircraft, hurricanes would destroy entire cities, like the Labor Day Hurricane in Key West back in 1935,” said Gail Skofronick-Jackson, the project scientist for NASA’s Global Precipitation Measurement mission at NASA's Goddard Space Flight Center in Greenbelt, Maryland. “You would have no idea if a hurricane was coming until it was too late.”

Hurricanes in the Atlantic Ocean can form when sub-Saharan thunderstorms travel westward with areas of lower pressure. These troughs are known as African Easterly Waves. Warm, moist air rises within the storm clouds, drawing air into the thunderstorms. Like an ice skater pulling in her arms to increase her spin, this inward moving air increases the rotation of the air within the storm cloud. Moving across the warm Atlantic, this cycle repeats on a daily basis, and, with a favorable environment, potentially accelerates to create a monstrous vortex powered by oceanic heat.


Image above: MTSTAT and CloudSat imagery of Typhoon Dolphin. Image Credits: Natalie D. Tourville/Colorado State University.

NASA uses an arsenal of instruments to learn more about how these storms progress as they form. These devices orbit Earth on a fleet of spacecraft, including Aqua, Terra, the Global Precipitation Measurement core observatory, NASA-NOAA's Suomi NPP satellite, Calipso, Jason-2 and CloudSat.

“There are typically multiple instruments on every spacecraft with various purposes that often complement each other,” said Eric Moyer, the Earth science operations manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We can see the progression of a storm from one day to the next using the Terra and Aqua satellites—a morning and afternoon view of every storm system, every day.”

What NASA Studies

These instruments analyze different aspects of these storms, such as rainfall rates, surface wind speed, cloud heights, ocean heat and environmental temperature and humidity. Observing these factors helps identify the potential for storm formation or intensification. Similarly, the data allows meteorologists to better predict where, when and how hard hurricanes will strike land.

NASA's RapidScat instrument that flies aboard the International Space Station measures surface winds over the ocean and is used to gather data on tropical cyclones. This can show where in a hurricane the strongest winds occur. RapidScat continues a long satellite record of these observations that began with NASA's QuikScat satellite.

Scientists must completely understand a hurricane to predict its trajectory and strength. This means meteorologists must peer inside the cloud itself.

“Looking at the cloud structure can help us understand the storm’s structure and location, which improves our forecasts,” said Michael Brennan, a senior hurricane specialist at the National Oceanic and Atmospheric Administration’s National Hurricane Center. “We heavily rely on the passive microwave imagers from satellites to see what is happening in the core of the storm.”


Image above: This 3-D view of the area northeast of Typhoon Dolphin's eye on May 16 created by data from NASA/JAXA's GPM core satellite shows heaviest rain over the open waters of the Pacific Ocean at a rate of over 65 mm (2.6 inches) per hour. Image Credits: NASA/SSAI/JAXA, Hal Pierce.

Passive microwave imagers aboard NASA’s Global Precipitation Measurement and NASA-NOAA's Suomi National Polar-orbiting Partnership missions can peer through cloud canopies, allowing scientists to observe where the water is churning in the clouds.

“Just like a doctor using x-rays to understand what’s happening in the human body, our radiometers can pierce the clouds and understand the cyclone’s structure,” Skofronick-Jackson said. “We learn about the amount of liquid water and falling snow in the cloud. Then we know how much water may fall out over land and cause floods.”

“Having satellites to watch the oceans is critical, and that will never change,” Skofronick-Jackson said. “Radars on Earth can only see a certain distance out in the ocean, so without spacecraft, you would need radars on every ship. With satellite data informing computer models, we can predict the storms’ paths, to the point where regions only need to evacuate half as much coastline as before. That’s important, because it costs a lot of money to pack up, move to a hotel and close down businesses.”

Computer Modeling

Computer modeling is another powerful NASA research tool.

NASA's Global Modeling and Assimilation Office, or GMAO works to improve the understanding of hurricanes and assess models and procedures for quality. GMAO helps to identify information that was missing and determines what services could be added to help future investigation and prediction of hurricane systems.


Image above: On July 14, RapidScat saw the sustained winds surrounding Claudette's center of circulation were no stronger than 21 meters per second with the exception of stronger winds in the southwestern quadrant. Image Credits: NASA JPL/Doug Tyler.

As NASA launches more sophisticated Earth-observing instruments, teams produce models with higher and higher resolutions, the ability to ingest such data, or the data assimilation procedure, increases. Each new instrument provides scientists and modelers a closer and more varied look at tropical cyclones. The higher the resolution of models and the capability of data assimilation systems, the easier it is to exploit data from satellite-borne instruments and to determine a hurricane’s intensity and size in terms of things such as the wind field and cloud extent.

Airborne Missions

NASA also conducts field missions to study hurricanes. With an arsenal of instruments, ranging from radiometers that read moisture levels; lidars that measure aerosols, moisture, and winds; dropsonde systems to measure high-resolution profiles of temperature, pressure, moisture, and winds; to Doppler radar systems to map the 3-D precipitation and winds within storms. These instruments monitor the structure and environment of hurricanes and tropical storms as they evolve.



Image above: NASA's Hurricane and Severe Storm Sentinel (HS3) ran its field campaign phase during the summers of 2012, 2013, and 2014 performed by Global Hawk well-suited for hurricane investigations. Image Credit: NASA.

The most recent NASA field mission to study hurricanes was the Hurricane and Severe Storm Sentinel or HS3. For three consecutive years, the HS3 mission investigated the processes that underlie hurricane formation and intensity change in the Atlantic Ocean basin. The mission used the Global Hawk, a high-altitude long-endurance aircraft capable of flights of 26 hours at altitudes above 55,000 ft. Flying from the Wallops Flight Facility in Virginia, the uninhabited Global Hawks could cover the entire Atlantic Ocean, enabling measurements of storms at early stages in the central or eastern Atlantic or spending 12-18 hours over storms in the western Atlantic.

A Future Mission

In 2016, NASA is launching the Cyclone Global Navigation Satellite System, a constellation of eight small satellites. CYGNSS will probe the inner core of hurricanes in such detail to better understand their rapid intensification. One advantage of CYGNSS is that it can get frequent measurements within storms.  This allows CYGNSS to make accurate measurements of ocean surface winds both in and near the eye of the storm throughout the lifecycle of tropical cyclones. The goal is to improve hurricane intensity forecasts.

NASA data and research allows scientists to observe the fundamental processes that drive hurricanes. Meteorologists incorporate this satellite, aircraft and computer modeling data into forecasts in the United States and around the world.

For more on NASA’s hurricane observations and research, visit: http://www.nasa.gov/hurricane

Related links:

NASA’s Global Precipitation Measurement mission: http://www.nasa.gov/mission_pages/GPM/main/

NASA-NOAA's Suomi NPP satellite: http://npp.gsfc.nasa.gov/

NASA-NOAA's Calipso satellite: http://www.nasa.gov/mission_pages/calipso/main/

NASA-NOAA's Jason-2 satellite: http://www.nasa.gov/mission_pages/ostm/main/

NASA-NOAA's CloudSat satellite: http://www.nasa.gov/mission_pages/cloudsat/main/

Terra and Aqua satellites: http://modis.gsfc.nasa.gov/about/

NASA's QuikScat satellite: https://winds.jpl.nasa.gov/missions/quikscat/

Hurricane and Severe Storm Sentinel or HS3: http://www.nasa.gov/mission_pages/hurricanes/missions/hs3/index.html#.VcJzJYtjpMa

Cyclone Global Navigation Satellite System (CYGNSS): http://www.nasa.gov/cygnss/

Images (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Max Gleber/Karl Hille.

Best regards, Orbiter.ch

Hubble Sees a "Mess of Stars"












NASA - Hubble Space Telescope patch.

Aug. 14, 2015

(Click on the image for enlarge)

Bursts of pink and red, dark lanes of mottled cosmic dust, and a bright scattering of stars — this NASA/ESA Hubble Space Telescope image shows part of a messy barred spiral galaxy known as NGC 428. It lies approximately 48 million light-years away from Earth in the constellation of Cetus (The Sea Monster).

Although a spiral shape is still just about visible in this close-up shot, overall NGC 428’s spiral structure appears to be quite distorted and warped, thought to be a result of a collision between two galaxies. There also appears to be a substantial amount of star formation occurring within NGC 428 — another telltale sign of a merger. When galaxies collide their clouds of gas can merge, creating intense shocks and hot pockets of gas, and often triggering new waves of star formation.

NGC 428 was discovered by William Herschel in December 1786. More recently a type of supernova designated SN2013ct was discovered within the galaxy by Stuart Parker of the BOSS (Backyard Observatory Supernova Search) project in Australia and New Zealand, although it is unfortunately not visible in this image.

This image was captured by Hubble’s Advanced Camera for Surveys (ACS) and Wide Field and Planetary Camera 2 (WFPC2).

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington. 

Related links:

Backyard Observatory Supernova Search (BOSS): http://bosssupernova.com/

Hubble’s Advanced Camera for Surveys (ACS): http://www.spacetelescope.org/about/general/instruments/acs/

Hubble’s Wide Field and Planetary Camera 2 (WFPC2): http://www.spacetelescope.org/about/general/instruments/wfpc2/

For images and more about this study and the Hubble Space Telescope, visit:

http://www.nasa.gov/hubble
http://hubblesite.org/
http://www.spacetelescope.org/

Image, Credits: ESA/Hubble and NASA and S. Smartt (Queen's University Belfast), Acknowledgements: Nick Rose and Flickr user penninecloud/Text credit: European Space Agency.

Best regards, Orbiter.ch

NASA Scientists Help Understand Newly Discovered Planet






Gemini Observatory logo.

Aug. 14, 2015

One of the best ways to learn how our solar system evolved is to look at younger star systems in the early stages of development. Recently, a team of astronomers including NASA scientists discovered a Jupiter-like planet within a young system that could serve as a decoder ring for understanding how planets formed around our sun.


Image above: Artistic conception of the Jupiter-like exoplanet 51 Eridani b, with the hot layers deep in its atmosphere glowing through the clouds. Because of its young age, this cousin of our own Jupiter is still hot and carries information on the way it was formed 20 million years ago. Image Credits: Danielle Futselaar and Franck Marchis, SETI Institute.

The new planet, called 51 Eridani (Eri) b, is the first exoplanet discovered by the Gemini Planet Imager (GPI), a new instrument operated by an international collaboration, and installed on the 8-meter Gemini South Telescope in Chile. The GPI was designed specifically for discovering and analyzing faint, young planets orbiting bright stars via “direct imaging,” in which astronomers use adaptive optics to sharpen the image of a target star, then block out its starlight. Any remaining incoming light is then analyzed, and the brightest spots indicate a possible planet.

“This is exactly the kind of planet we envisioned discovering when we designed GPI”, says James Graham, professor at the University of California, Berkeley, and project scientist for GPI.

8-meter Gemini South Telescope in Chile. Image Credit: Gemini Observatory

Other methods of planet detection are indirect, such as the transit method used by NASA's Kepler mission, in which it discovers planets by measuring the loss of starlight when a planet passes in front of its star.

As Bruce Macintosh, a professor of physics at Stanford University and member of the Kavli Institute for Particle Astrophysics and Cosmology figuratively described, to detect planets, Kepler sees their shadow while GPI sees their glow.

As far as the cosmic clock is concerned, 51 Eridani is young – only 20 million years old – and this made the direct detection of the planet possible. When planets coalesce, material falling into the planet releases energy and heats it up. Over the next hundred millions years, they radiate that energy away, mostly as infrared light.

“Many of the exoplanets astronomers have imaged before have atmospheres that look like very cool stars" said Macintosh, who led the construction of GPI and now leads the planet-hunting survey. "This one looks like a planet.”

GPI observations revealed that 51 Eri b is roughly twice the mass of Jupiter. Other directly-imaged planets are five times the mass of Jupiter or more. In addition to being the lowest-mass exoplanet ever imaged, it's also the coldest – 800 degrees Fahrenheit, whereas others are around 1,200 F – and it features the strongest atmospheric methane signal ever detected on an alien planet.

Previous Jupiter-like exoplanets have shown only faint traces of methane, far different from the distinctive signatures of methane seen in the atmospheres of the gas giants in our solar system. All of these characteristics, researchers say, point to a planet that is very much what models suggest Jupiter was like in its infancy.


Image above: Discovery image of the exoplanet 51 Eridani b taken in the near-infrared light with the Gemini Planet Imager on Dec. 21, 2014. The bright central star has been mostly removed to enable the detection of the million-times fainter planet. Image Credits: Gemini Observatory and J. Rameau (UdeM) and C. Marois NRC Herzberg.

In the atmospheres of the cold giant planets of our solar system, carbon is found as methane, unlike most exoplanets where carbon has mostly been found in the form of carbon monoxide. “Since the atmosphere of 51 Eri b is also methane rich, it signifies that this planet is well on its way to becoming a cousin of our own familiar Jupiter,” said Mark Marley, an astrophysicist at NASA’s Ames Research Center in Moffett Field, California, co-lead for theory and a team member responsible for helping to interpret GPI observations.

In addition to expanding the universe of known planets, GPI will provide key clues as to how solar systems form. Astronomers believe that the gas giants in our solar system formed by building up a large, core over a few million years and then pulling in a huge amount of hydrogen and other gasses to form an atmosphere. But the Jupiter-like exoplanets that have been discovered are much hotter than models have predicted, hinting that they could have formed much faster as material collapsed quickly to make a very hot planet. This is an important difference. Using GPI to study more young solar systems such as 51 Eridani will help astronomers understand the formation of our neighbor planets, and how common that planet-forming mechanism is throughout the universe.

"The newly discovered 51 Eri b is the first planet that's cold enough and close enough to the star that it could have indeed formed right where it is the 'old-fashioned way,” Macintosh said. "This planet really could have formed the same way Jupiter did - the whole solar system could be a lot like ours."

The results are published in the current issue of Science Express and in the August 20 issue of Science.

GPI was constructed by a consortium of American and Canadian institutions, funded by the Gemini Observatory, which is an international partnership comprising the United States, United Kingdom, Canada, Australia, Argentina, Brazil and Chile. The Gemini Planet Imager Exoplanet Survey (GPIES) campaign is partially funded by National Science Foundation (NSF), NASA, the University of California and the Laboratory Directed Research and Development funding at the Lawrence Livermore National Laboratory.

For more information about Distant Planets, visit: http://www.nasa.gov/subject/6889/distant-planets

Gemini Planet Imager (GPI): http://planetimager.org/

Gemini Observatory: http://www.gemini.edu/

Images (mentioned), Text, Credits: NASA/Ames Research Center/Darryl Waller/Jessica Culler.

Greetings, Orbiter.ch

NASA’s Hubble Finds Supernovae in ‘Wrong Place at Wrong Time’











NASA - Hubble Space Telescope patch.

Aug. 14, 2015

Scientists have been fascinated by a series of unusual exploding stars — outcasts beyond the typical cozy confines of their galaxies. A new analysis of 13 supernovae — including archived data from NASA’s Hubble Space Telescope — is helping astronomers explain how some young stars exploded sooner than expected, hurling them to a lonely place far from their host galaxies.

It’s a complicated mystery of double-star systems, merging galaxies, and twin black holes that began in 2000 when the first such supernova was discovered, according to study leader Ryan Foley, University of Illinois at Urbana-Champaign. “This story has taken lots of twists and turns, and I was surprised every step of the way,” he said. “We knew these stars had to be far from the source of their explosion as supernovae and wanted to find out how they arrived at their current homes.”


Image above: These Hubble Space Telescope images show elliptical galaxies with dark, wispy dust lanes, the signature of a recent galaxy merger. The dust is the only relic of a smaller galaxy that was consumed by the larger elliptical galaxy.The "X" in the images marks the location of supernova explosions that are associated with the galaxies. Each supernova may have been gravitationally kicked out of its host galaxy by a pair of central supermassive black holes. SN 2000ds (left) is at least 12,000 light-years from its galaxy, NGC 2768; SN 2005cz (right) is at least 7,000 light-years from its galaxy, NGC 4589. NGC 2768 resides 75 million light-years from Earth, and NGC 4589 is 108 million light-years away.The supernovae are part of a census of 13 supernovae to determine why they detonated outside the cozy confines of galaxies. The study is based on archived images made by several telescopes, including Hubble. Both galaxies were observed by Hubble's Advanced Camera for Surveys. The image of NGC 4589 was taken on Nov. 11, 2006, and the image of NGC 2768 on May 31, 2002. Image Credits: NASA, ESA, and R. Foley (University of Illinois).

Foley thought that the doomed stars had somehow migrated to their final resting spots. To prove his idea, he studied data from the Lick Observatory in California and the W. M. Keck Observatory and the Subaru Telescope, both in Hawaii, to determine how fast the stars were traveling. To his surprise, he discovered that the doomed stars were zipping along at about the same speed as stars that have been tossed out of our Milky Way galaxy by its central supermassive black hole, at more than 5 million miles (7 million kilometers) an hour.

The astronomer then turned his attention to the aging galaxies in the area of the speeding supernovae. Studying Hubble archival images, he confirmed that many are massive elliptical galaxies that were merging or had recently merged with other galaxies. The lanes are the shredded remnants of a cannibalized galaxy. Other observations provided circumstantial evidence for such encounters, showing that the cores of many of these galaxies had active supermassive black holes fueled by the collision. Many of the galaxies also reside in dense environments at the heart of galaxy clusters, a prime area for mergers. The telltale clue was strong dust lanes piercing through the centers of several of them.

video
Hubble orbiting Earth

The location of the supernovae in relation to ancient galaxies indicates that the original stars must have been old, too, Foley reasoned. And if the stars were old, then they must have had companions with them that provided enough material to trigger a supernova blast.

How does a double-star system escape the boundaries of a galaxy?

Foley hypothesizes that a pair of supermassive black holes in the merging galaxies can provide the gravitational slingshot to rocket the binary stars into intergalactic space. Hubble observations reveal that nearly every galaxy has a massive black hole at its center. According to Foley’s scenario, after two galaxies merge, their black holes migrate to the center of the new galaxy, each with a trailing a cluster of stars. As the black holes dance around each other, slowly getting closer, one of the binary stars in the black holes’ entourage may wander too close to the other black hole. Many of these stars will be flung far away, and those ejected stars in surviving binary systems will orbit even closer after the encounter, which speeds up the merger.


Images above: This illustration offers a plausible scenario for how vagabond stars exploded as supernovae outside the cozy confines of galaxies.1) A pair of black holes comes together during a galaxy merger, dragging with them up to a million stars each.2) A double-star system wanders too close to the two black holes.3) The black holes then gravitationally catapult the stars out of the galaxy. At the same time, the stars are brought closer together.4) After getting booted out of the galaxy, the binary stars move even closer together as orbital energy is carried away from the duo in the form of gravitational waves.5) Eventually, the stars get close enough that one of them is ripped apart by tidal forces.6) As material from the dead star is quickly dumped onto the surviving star, a supernova occurs. Images Credits: NASA, ESA, and P. Jeffries and A. Feild (STScI).

“With a single black hole, occasionally a star will wander too close to it and have an extreme interaction,” Foley said. “With two black holes, there are two reservoirs of stars being dragged close to another black hole. This dramatically increases the likelihood that a star is ejected.” While the black hole at the center of the Milky Way may eject about one star a century, a binary supermassive black hole may kick out 100 stars a year.

After getting booted out of the galaxy, the binary stars move closer together as their orbits continue to accelerate which speeds up the binary stars’ aging process. The binary stars are likely both white dwarfs, which are burned out relics of stars. Eventually, the white dwarfs get close enough that one is ripped apart by tidal forces. As material from the dead star is quickly dumped onto the surviving star, an explosion occurs, causing the supernova.

The time it takes for one of these ejected stars to explode is relatively short, about 50 million years. Normally, these kinds of binary stars take a long time to merge, probably much longer than the age of the universe, which is more than 13 billion years.

“The interaction with the black holes shortens that fuse,” Foley explained.

While scientists think they have found what causes these outcast supernovae, some mysteries remain unsolved, such as why they are unusually weak. These supernovae produced more than five times as much calcium as other stellar explosions. Normally, supernova explosions have enough energy to create much heavier elements, such as iron and nickel, at the expense of producing the lighter calcium. However, for these atypical explosions, the fusion chain stops midway, leaving lots of calcium and very little iron.

“Everything points to a weak explosion,” said Foley. “We know that these blasts have lower kinetic energy and less luminosity than typical supernovae. They also appear to have less ejected mass, whereas a more energetic explosion should completely unbind the star.”

The results appear in the Aug. 13 issue of the Monthly Notices of the Royal Astronomical Society: http://mnras.oxfordjournals.org/content/452/3/2463.full?sid=70ce50c3-f92e-46fe-977e-83b3af63f3d9

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington.

For images and more about this study and the Hubble Space Telescope, visit:

http://www.nasa.gov/hubble
http://hubblesite.org/
http://www.spacetelescope.org/

Images (mentioned), Video, Text, Credits: NASA/ESA/Rob Garner.

Greetings, Orbiter.ch

jeudi 13 août 2015

Cassini to Make Last Close Flyby of Saturn Moon Dione










NASA - Cassini International logo.

Aug. 13, 2015

NASA's Cassini spacecraft will zip past Saturn's moon Dione on Monday, Aug. 17 -- the final close flyby of this icy satellite during the spacecraft's long mission.

Cassini’s closest approach, within 295 miles (474 kilometers) of Dione's surface, will occur at 11:33 a.m. PDT (2:33 p.m. EDT). Mission controllers expect fresh images to begin arriving on Earth within a couple of days following the encounter.


Image above: A view of Saturn's moon Dione captured by NASA's Cassini spacecraft during a close flyby on June 16, 2015. The diagonal line near upper left is the rings of Saturn, in the distance. Image Credits: NASA/JPL-Caltech/Space Science Institute.

Cassini scientists have a bevy of investigations planned for Dione. Gravity-science data from the flyby will improve scientists' knowledge of the moon's internal structure and allow comparisons to Saturn's other moons. Cassini has performed this sort of gravity science investigation with only a handful of Saturn's 62 known moons.

During the flyby, Cassini's cameras and spectrometers will get a high-resolution peek at Dione's north pole at a resolution of only a few feet (or meters). In addition, Cassini's Composite Infrared Spectrometer instrument will map areas on the icy moon that have unusual thermal anomalies -- those regions are especially good at trapping heat. Meanwhile, the mission's Cosmic Dust Analyzer continues its search for dust particles emitted from Dione.

This flyby will be the fifth targeted encounter with Dione of Cassini's tour at Saturn. Targeted encounters require maneuvers to precisely steer the spacecraft toward a desired path above a moon. The spacecraft executed a 12-second burn using its thrusters on Aug. 9, which fine-tuned the trajectory to enable the upcoming encounter.


Image above: Artist's view of  the Cassini's encounter with Saturn's moon Dione. Image Credits: NASA/JPL-Caltech.

Cassini’s closest-ever flyby of Dione was in Dec. 2011, at a distance of 60 miles (100 kilometers). Those previous close Cassini flybys yielded high-resolution views of the bright, wispy terrain on Dione first seen during the Voyager mission. Cassini's sharp views revealed the bright features to be a system of braided canyons with bright walls. Scientists also have been eager to find out if Dione has geologic activity, like Saturn's geyser-spouting moon Enceladus, but at a much lower level.

"Dione has been an enigma, giving hints of active geologic processes, including a transient atmosphere and evidence of ice volcanoes. But we've never found the smoking gun. The fifth flyby of Dione will be our last chance," said Bonnie Buratti, a Cassini science team member at NASA's Jet Propulsion Laboratory in Pasadena, California.

Cassini has been orbiting Saturn since 2004. After a series of close moon flybys in late 2015, the spacecraft will depart Saturn's equatorial plane -- where moon flybys occur most frequently -- to begin a year-long setup of the mission's daring final year. For its grand finale, Cassini will repeatedly dive through the space between Saturn and its rings.

"This will be our last chance to see Dione up close for many years to come," said Scott Edgington, Cassini mission deputy project scientist at JPL. "Cassini has provided insights into this icy moon's mysteries, along with a rich data set and a host of new questions for scientists to ponder."

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. JPL, a division of the California Institute of Technology, manages the mission for NASA's Science Mission Directorate in Washington.

For more information about Cassini, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov
and http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Images (mentioned), Text, Credits: NASA/JPL/Preston Dyches/Tony Greicius.

Greetings, Orbiter.ch

Rosetta's big day in the Sun












ESA - Rosetta Mission patch.

13 August 2015

ESA’s Rosetta today witnessed Comet 67P/Churyumov–Gerasimenko making its closest approach to the Sun. The exact moment of perihelion occurred at 02:03 GMT this morning when the comet came within 186 million km of the Sun.

Approaching perihelion

In the year that has passed since Rosetta arrived, the comet has travelled some 750 million kilometres along its orbit towards the Sun, the increasing solar radiation heating up the nucleus and causing its frozen ices to escape as gas and stream out into space at an ever greater rate. These gases, and the dust particles that they drag along, build up the comet’s atmosphere – coma – and tail.

The activity reaches its peak intensity around perihelion and in the weeks that follow – and is clearly visible in the spectacular images returned by the spacecraft in the last months. One image taken by Rosetta’s navigation camera was acquired at 01:04 GMT, just an hour before the moment of perihelion, from a distance of around 327 km.

Approaching perihelion – Animation

The scientific camera is also taking images today – the most recent available image was taken at 23:31 GMT on 12 August, just a few hours before perihelion. The comet’s activity is clearly seen in the images, with a multitude of jets stemming from the nucleus, including one outburst captured in an image taken at 17:35 GMT yesterday.

“Activity will remain high like this for many weeks, and we’re certainly looking forward to seeing how many more jets and outburst events we catch in the act, as we have already witnessed in the last few weeks,” says Nicolas Altobelli, acting Rosetta project scientist.

Rosetta’s measurements suggest the comet is spewing up to 300 kg of water vapour – roughly the equivalent of two bathtubs – every second. This is a thousand times more than was observed this time last year when Rosetta first approached the comet. Then, it recorded an outflow rate of just 300 g per second, equivalent to two small glasses of water.

Comet at perihelion

Along with gas, the nucleus is also estimated to be shedding up to 1000 kg of dust per second, creating dangerous working conditions for Rosetta.

“In recent days, we have been forced to move even further away from the comet. We’re currently at a distance of between 325 km and 340 km this week, in a region where Rosetta’s startrackers can operate without being confused by excessive dust levels – without them working properly, Rosetta can’t position itself in space,” comments Sylvain Lodiot, ESA’s spacecraft operations manager.

Boulder flying by comet

Monitoring the comet’s changing environment in the lead up to, during and after perihelion is one of the primary long-term science goals of the mission.

Over the last few months, seasons on the comet have changed, throwing its southern hemisphere into a short – about 10 month – summer after more than five-and-a-half years in darkness. This has revealed parts of the surface that have previously been cast in shadow during Rosetta’s sojourn at the comet, allowing scientists to fill in some of the missing pieces of its regional map.

Comet southern hemisphere

They have now identified four new geological regions on the southern hemisphere, which includes parts of both comet lobes, bringing the total number of regions to 23. The names of the new regions follow the naming convention of Egyptian gods and goddesses adopted for the comet: Anhur, Khonsu, Sobek and Wosret. 

The comet’s average temperature has also been on the increase. Not long after arriving, surface temperatures of around –70ºC were recorded. By April–May 2015, this had risen to only a few degrees below zero celsius, and now highs of a few tens of degrees above zero are forecast for the next month.

Comet observed from Earth

Meanwhile, astronomers back on Earth have been following the comet’s evolution from afar. Rosetta is far too close to the comet to see its growing tail, but images collected over the past few months with telescopes across the world show that it already extends more than 120 000 km. 

A lop-sided coma, with a notable high-density region away from the main tail, was revealed in various images, including some taken last week from the Gemini-North telescope on Mauna Kea, Hawaii.

Mapping comet jets

“Combining these big-picture views from ground-based telescopes with Rosetta’s close-up study of individual jets and outbursts will help us to understand the processes at work on the comet’s surface as it approaches the Sun,” adds Nicolas.

“We aim to go back in much closer again after the activity subsides and make a survey of how the comet has changed. We also continue to hope that Philae will be able to resume its scientific operations on the surface and give us a detailed look at changes which may be occurring immediately surrounding its landing site.”

Comet’s dusty environment

Finally, Patrick Martin, ESA’s Rosetta mission manager remarks: “It’s exciting to reach the milestone of perihelion, and we look forward to seeing how this amazing comet behaves as we move away from the Sun with it over the coming year.”

Notes for Editors:

A Google+ Hangout with Rosetta mission experts, celebrating a year at the comet and perihelion, was broadcast today. Watch a replay here: https://youtu.be/TaBZbc6WGLs

About Rosetta:

Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander is contributed by a consortium led by DLR, MPS, CNES and ASI.

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

Where is Rosetta?: http://sci.esa.int/where_is_rosetta/

Rosetta overview: http://www.esa.int/Our_Activities/Space_Science/Rosetta_overview

Rosetta in depth:http://sci.esa.int/rosetta

Rosetta factsheet: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_factsheet

Frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions

Images, Animations, Text, Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA/NAVCAM – CC BY-SA IGO 3.0.

Best regards, Orbiter.ch

mercredi 12 août 2015

BASE compares protons to antiprotons with high precision












CERN - European Organization for Nuclear Research logo.

August 12, 2015

In a paper published today in Nature, the Baryon Antibaryon Symmetry Experiment (BASE) at CERN's Antiproton Decelerator (AD), reports the most precise comparison of the charge-to-mass ratio of the proton to that of its antimatter equivalent, the antiproton. The charge-to-mass ratio — an important property of particles — can be measured by observing the oscillation of a particle in a magnetic field. The new result shows no difference between the proton and the antiproton, with a four-fold improvement in the energy resolution compared with previous measurements.

To perform the experiment, the BASE collaboration used a Penning-trap system comparable to that developed by the TRAP collaboration in the late 1990s at CERN. However, the method used is faster than in previous experiments. This has allowed BASE to carry out about 13,000 measurements over a 35-day campaign, in which they compare a single antiproton to a negatively charged hydrogen ion (H-). Consisting of a hydrogen atom with a single proton in its nucleus, together with an additional electron, the H- acts as a proxy for the proton.

“We found that the charge-to-mass ratio is identical to within 69 parts per thousand billion, supporting a fundamental symmetry between matter and antimatter,” says BASE spokesperson Stefan Ulmer.

“Research performed with antimatter particles has made amazing progress in the past few years,” says CERN Director-General Rolf Heuer. “I’m really impressed by the level of precision reached by BASE. It’s very promising for the whole field.”


Image above: A cut-away schematic of the Penning trap system used by BASE. The experiment receives antiprotons from CERN's AD; negative hydrogen ions are formed during injection into the apparatus. The set-up works with only a pair of particles at a time, while a cloud of a few hundred others are held in the reservoir trap, for future use. Here, an antiproton is in the measurement trap, while the negative hydyrogen ion is in held by the downstream park electrode. When the antiproton has been measured, it is moved to the upstream park electrode and the hydrogen ion is brought in to the measurement trap. This is repeated thousands of times, enabling a high-precision comparison of the charge-to-mass ratios of the two particles (Image: CERN).

The Standard Model of particle physics – the theory that best describes particles and their fundamental interactions – is known to be incomplete, inspiring various searches for “new physics” that goes beyond the model. These include tests that compare the basic characteristics of matter particles with those of their antimatter counterparts. While matter and antimatter particles can differ, for example, in the way they decay (a difference often referred to as violation of CP symmetry), other fundamental properties, such as the absolute value of their electric charges and masses, are predicted to be exactly equal. Any difference – however small — between the charge-to-mass ratio of protons and antiprotons would break a fundamental law known as CPT symmetry. This symmetry reflects well-established properties of space and time and of quantum mechanics, so such a difference would constitute a dramatic challenge not only to the Standard Model, but also to the basic theoretical framework of particle physics.

The BASE experiment receives antiprotons from the AD, a unique facility in the world for antimatter research. The H- ions are formed by the antiproton injection. The set up holds a single antiproton–H- pair at a time in a magnetic Penning trap, decelerating the particles to ultra-low energies. The experiment then measures the cyclotron frequency of the antiproton and the H- ion — a measurement that allows the team to determine the charge-to-mass ratio — and compares the results.

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

Related links:

Baryon Antibaryon Symmetry Experiment (BASE): http://base.web.cern.ch/

CERN's Antiproton Decelerator (AD): http://home.web.cern.ch/about/accelerators/antiproton-decelerator

The Standard Model of particle physics: http://home.web.cern.ch/about/physics/standard-model

Antimatter: http://home.web.cern.ch/topics/antimatter

For more information about European Organization for Nuclear Research (CERN), visit: http://home.web.cern.ch/

Image (mentioned), Text, Credits: CERN/Cian O'Luanaigh.

Best regards, Orbiter.ch

Gecko Grippers Moving On Up












ISS - International Space Station patch.

Aug. 12, 2015

Space Technology

A piece of tape can only be used a few times before the adhesion wears off and it can no longer hold two surfaces together. But researchers at NASA's Jet Propulsion Laboratory in Pasadena, California, are working on the ultimate system of stickiness, inspired by geckos.

video
Crazy Engineering: Gecko Gripper

Video above: How geckos inspired a new NASA technology that makes things stick to each other in space. Video Credits: NASA/JPL.

Thanks to tiny hairs on the bottom of geckos' feet, these lizards can cling to walls with ease, and their stickiness doesn't wear off with repeated usage. JPL engineer Aaron Parness and colleagues used that concept to create a material with synthetic hairs that are much thinner than a human hair. When a force is applied to make the tiny hairs bend, that makes the material stick to a desired surface.

"This is how the gecko does it, by weighting its feet," Parness said.

Behind this phenomenon is a concept called van der Waals forces. A slight electrical field is created because electrons orbiting the nuclei of atoms are not evenly spaced, so there are positive and negative sides to a neutral molecule.  The positively charged part of a molecule attracts the negatively charged part of its neighbor, resulting in "stickiness." Even in extreme temperature, pressure and radiation conditions, these forces persist.

"The grippers don't leave any residue and don't require a mating surface on the wall the way Velcro would," Parness said.

The newest generation of grippers can support more than 150 Newtons of force, the equivalent of 35 pounds (16 kilograms).


Image above: This artist's concept shows how a future robot called LEMUR (Limbed Excursion Mechanical Utility Robot) could inspect and maintain installations on the International Space Station. The robot would stick to the outside using a gecko-inspired gripping system. Image Credits: NASA/JPL-Caltech.

In a microgravity flight test last year through NASA's Space Technology Mission Directorate’s Flight Opportunities Program, the gecko-gripping technology was used to grapple a 20-pound (10 kilogram) cube and a 250-pound (100 kilogram) person. The gecko material was separately tested in more than 30,000 cycles of turning the stickiness "on" and "off" when Parness was in graduate school at Stanford University in Palo Alto, California. Despite the extreme conditions, the adhesive stayed strong.


Image above: JPL researchers were inspired by gecko feet, such as the one shown here, in designing a gripping system for space. Just as a gecko's foot has tiny adhesive hairs, the JPL devices have small structures that work in similar ways. Image Credits: Wikimedia Commons.

Researchers have more recently made three sizes of hand-operated "astronaut anchors," which could one day be given to astronauts inside the International Space Station. The anchors are made currently in footprints of 1 by 4 inches (2.5 by 10 centimeters), 2 by 6 inches (5 by 15 centimeters) and 3 by 8 inches (7.6 by 20 centimeters).  They would serve as an experiment to test the gecko adhesives in microgravity for long periods of time and as a practical way for astronauts to attach clipboards, pictures and other handheld items to the interior walls of the station. Astronauts would simply attach the object to the mounting post of the gripper by pushing together the two components of the gripper. Parness and colleagues are collaborating with NASA's Johnson Space Center in Houston on this concept.


Image above: The gecko grippers could one day be used to mount objects on the inside of the International Space Station. This image shows a gripper attaching a clipboard to a spare panel -- the same kind found inside the United States' modules of the station. Image Credits: NASA/JPL-Caltech.

Parness and his team are also testing the Lemur 3 climbing robot, which has gecko-gripper feet, in simulated microgravity environments. The team thinks possible applications could be to have robots like this on the space station conducting inspections and making repairs on the exterior. For testing, the robot maneuvers across mock-up solar and radiator panels to emulate that environment.

There are numerous applications beyond the space station for this technology.

"We might eventually grab satellites to repair them, service them, and we also could grab space garbage and try to clear it out of the way," Parness said.

The California Institute of Technology in Pasadena manages JPL for NASA.

Related links:

International Space Station (ISS): http://www.nasa.gov/mission_pages/station/main/index.html

Jet Propulsion Laboratory (JPL): http://www.nasa.gov/centers/jpl/home/index.html

Images (mentioned), Video (mentioned), Text, Credits: NASA/JPL/Elizabeth Landau/Tony Greicius.

Best regards, Orbiter.ch

mardi 11 août 2015

NASA's Terra Satellite Sees Molave Regain Tropical Storm Status












NASA - EOS TERRA Mission patch.

Aug. 11, 2015

Tropical Depression Molave (Northwest Pacific)

 
Image above: On Aug. 11 at 8:05 a.m. EDT the MODIS instrument aboard NASA's Terra satellite captured this infrared image fragmented strong storms (red) in Tropical Storm Molave's northern quadrant. Image Credits: NASA Goddard MODIS Rapid Response Team.

Tropical Depression Molave showed a burst of thunderstorm development when NASA's Terra satellite passed overhead on August 11, as it regained tropical storm status.

On Aug. 4 at 4:00 UTC (12:00 a.m. EDT) the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA's Terra satellite captured an infrared image of a stronger Tropical Storm Molave. The infrared imagery revealed fragmented, but very cold thunderstorm cloud tops northwest, north and northeast of the center of circulation. Those cold cloud tops were indicative of stronger convection (rising air that forms thunderstorms).


Image above: On August 9 at 01:20 UTC (Aug. 8 at 9:20 p.m. EDT), NASA's Terra satellite captured a visible-light image of Tropical Depression Molave winding down about 400 miles away from Yokosuka, Japan. Image Credits: NASA Goddard MODIS Rapid Response, Jeff Schmaltz.

At 1500 UTC (11 a.m. EDT) on August 11, Molave's maximum sustained winds increased to near 45 knots (51.7 mph/83.3 kph). It was centered near 32.5 North latitude and 144.5 East longitude, about 292 nautical miles (336 miles/540.8 km) southeast of Yokosuka, Japan. Molave was moving to the west-northwest at 8 knots (9.2 mph/14.8 kph).

TERRA satellite. Image Credit: NASA

As Molave moves to the northeast, the storm is intensifying. The Joint Typhoon Warning Center expects Molave to peak at 60 knots (69 mph/111 kph) before becoming extra-tropical southeast of Kamchatka.

For more information about  Terra Satellite, visit: http://www.nasa.gov/mission_pages/terra/index.html

Images (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Rob Gutro.

Greetings, Orbiter.ch

Oxymoronic Black Hole Provides Clues to Growth













NASA - Chandra X-ray Observatory patch.

Aug. 11, 2015

Astronomers using NASA’s Chandra X-ray Observatory and the 6.5-meter Clay Telescope in Chile have identified the smallest supermassive black hole ever detected in the center of a galaxy. This oxymoronic object could provide clues to how larger black holes formed along with their host galaxies 13 billion years or more in the past.

Astronomers estimate this supermassive black hole is about 50,000 times the mass of the sun. This is less than half the mass of the previous smallest black hole at the center of a galaxy.


Image above: A Sloan Digital Sky Survey image of RGG 118, a galaxy containing the smallest supermassive black hole ever detected. The inset is a Chandra image showing hot gas around the black hole. Image Credits: NASA/CXC/Univ of Michigan/V.F.Baldassare, et al; Optical: SDSS.

“It might sound contradictory, but finding such a small, large black hole is very important,” said Vivienne Baldassare of the University of Michigan in Ann Arbor, first author of a paper on these results published in The Astrophysical Journal Letters. “We can use observations of the lightest supermassive black holes to better understand how black holes of different sizes grow.”

The tiny heavyweight black hole is in the center of a dwarf disk galaxy, called RGG 118, located about 340 million light years from Earth, and was originally discovered using the Sloan Digital Sky Survey.

Researchers estimated the mass of the black hole by studying the motion of cool gas near the center of the galaxy using visible light data from the Clay Telescope. They used the Chandra data to figure out the X-ray brightness of hot gas swirling toward the black hole. They found the outward push of radiation pressure of this hot gas is about 1 percent of the black hole’s inward pull of gravity, matching the properties of other supermassive black holes.

Previously, scientists had noted a relationship between the mass of supermassive black holes and the range of velocities of stars in the center of their host galaxy. This relationship also holds for RGG 118 and its black hole.

“We found this little supermassive black hole behaves very much like its bigger, and in some cases much bigger, cousins,” said co-author Amy Reines of the University of Michigan. “This tells us black holes grow in a similar way no matter what their size.”

The black hole in RGG 118 is nearly 100 times less massive than the supermassive black hole found in the center of the Milky Way. It’s also about 200,000 times less massive than the heaviest black holes found in the centers of other galaxies.

Astronomers are trying to understand the formation of billion-solar-mass black holes from less than a billion years after the big bang, but many are undetectable with current technology. The black hole in RGG 118 gives astronomers an opportunity to study a nearby small supermassive black hole.

Chandra X-ray Observatory. Image Credits: NASA/CXC

Astronomers think supermassive black holes may form when a large cloud of gas, with a mass of about 10,000 to 100,000 times that of the sun, collapses into a black hole. Many of these black hole seeds then merge to form much larger supermassive black holes. Alternately, a supermassive black hole seed could come from a giant star, about 100 times the sun’s mass, that ultimately forms into a black hole after it runs out of fuel and collapses.

“We have two main ideas for how these supermassive black holes are born,” said Elena Gallo of the University of Michigan. “This black hole in RGG 118 is serving as a proxy for those in the very early universe and ultimately may help us decide which of the two is right.”

Researchers will continue to look for other supermassive black holes that are comparable in size or even smaller than the one in RGG 118 to help decide which of the models is more accurate and refine their understanding of how these objects grow.

A preprint of these results is available online (http://arxiv.org/abs/1506.07531). The other co-author of the paper is Jenny Greene, from Princeton University in Princeton, New Jersey. NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, manages Chandra's science and flight operations.

An interactive image, podcast, and a video about the findings are available at: http://chandra.si.edu

For more Chandra images, multimedia and related materials, visit: http://www.nasa.gov/chandra

Images (mentioned), Text, Credits: NASA/Felicia Chou/Chandra X-ray Center/Megan Watzke/Karen Northon.

Greetings, Orbiter.ch

Comet Firework Display Ahead of Perihelion












ESA - Rosetta Mission patch.

11 August 2015

In the approach to perihelion over the past few weeks, Rosetta has been witnessing growing activity from Comet 67P/Churyumov–Gerasimenko, with one dramatic outburst event proving so powerful that it even pushed away the incoming solar wind.

The comet reaches perihelion on Thursday, the moment in its 6.5-year orbit when it is closest to the Sun. In recent months, the increasing solar energy has been warming the comet’s frozen ices, turning them to gas, which pours out into space, dragging dust along with it.

Outburst in action

The period around perihelion is scientifically very important, as the intensity of the sunlight increases and parts of the comet previously cast in years of darkness are flooded with sunlight.

Although the comet’s general activity is expected to peak in the weeks following perihelion, much as the hottest days of summer usually come after the longest days, sudden and unpredictable outbursts can occur at any time – as already seen earlier in the mission.

On 29 July, Rosetta observed the most dramatic outburst yet, registered by several of its instruments from their vantage point 186 km from the comet. They imaged the outburst erupting from the nucleus, witnessed a change in the structure and composition of the gaseous coma environment surrounding Rosetta, and detected increased levels of dust impacts.

Perhaps most surprisingly, Rosetta found that the outburst had pushed away the solar wind magnetic field from around the nucleus.

Discovery of diamagnetic cavity

A sequence of images taken by Rosetta’s scientific camera OSIRIS show the sudden onset of a well-defined jet-like feature emerging from the side of the comet’s neck, in the Anuket region. It was first seen in an image taken at 13:24 GMT, but not in an image taken 18 minutes earlier, and has faded significantly in an image captured 18 minutes later. The camera team estimates the material in the jet to be travelling at 10 m/s at least, and perhaps much faster.

“This is the brightest jet we’ve seen so far,” comments Carsten Güttler, OSIRIS team member at the Max Planck Institute for Solar System Research in Göttingen, Germany.

“Usually, the jets are quite faint compared to the nucleus and we need to stretch the contrast of the images to make them visible – but this one is brighter than the nucleus.”

Soon afterwards, the comet pressure sensor of ROSINA detected clear indications of changes in the structure of the coma, while its mass spectrometer recorded changes in the composition of outpouring gases.

For example, compared to measurements made two days earlier, the amount of carbon dioxide increased by a factor of two, methane by four, and hydrogen sulphide by seven, while the amount of water stayed almost constant.

Gas changes during 29 July outburst

“This first ‘quick look’ at our measurements after the outburst is fascinating,” says Kathrin Altwegg, ROSINA principal investigator at the University of Bern. “We also see hints of heavy organic material after the outburst that might be related to the ejected dust.

“But while it is tempting to think that we are detecting material that may have been freed from beneath the comet's surface, it is too early to say for certain that this is the case.”

Meanwhile, about 14 hours after the outburst, GIADA was detecting dust hits at rates of 30 per day, compared with just 1–3 per day earlier in July. A peak of 70 hits was recorded in one 4-hour period on 1 August, indicating that the outburst continued to have a significant effect on the dust environment for the following few days.

“It was not only the abundance of the particles, but also their speeds measured by GIADA that told us something ‘different’ was happening: the average particle speed increased from 8 m/s to about 20 m/s, with peaks at 30 m/s – it was quite a dust party!” says Alessandra Rotundi, principal investigator at the ‘Parthenope’ University of Naples, Italy.

Perhaps the most striking result is that the outburst was so intense that it actually managed to push the solar wind away from the nucleus for a few minutes – a unique observation made by the Rosetta Plasma Consortium’s magnetometer.

The solar wind is the constant stream of electrically charged particles that flows out from the Sun, carrying its magnetic field out into the Solar System. Earlier measurements made by Rosetta and Philae had already shown that the comet is not magnetised,  so the only source for the magnetic field measured around it is the solar wind.

29 July outburst context

But it doesn’t flow past unimpeded. Because the comet is spewing out gas, the incoming solar wind is slowed to a standstill where it encounters that gas and a pressure balance is reached.

“The solar wind magnetic field starts to pile up, like a traffic jam, and eventually stops moving towards the comet nucleus, creating a magnetic field-free region on the Sun-facing side of the comet called a ‘diamagnetic cavity’,” explains Charlotte Götz, magnetometer team member at the Institute for Geophysics and extraterrestrial Physics in Braunschweig, Germany.

Diamagnetic cavities provide fundamental information on how a comet interacts with the solar wind, but the only previous detection of one associated with a comet was made at about 4000 km from Comet Halley as ESA’s Giotto flew past in 1986.

Rosetta’s comet is much less active than Halley, so scientists expected to find a much smaller cavity around it, up to a few tens of kilometres at most, and prior to 29 July, had not observed any sign of one.

But, following the outburst on that day, the magnetometer detected a diamagnetic cavity extending out at least 186 km from the nucleus. This was likely created by the outburst of gas, which increased the neutral gas flux in the comet’s coma, forcing the solar wind to ‘stop’ further away from the comet and thus pushing the cavity boundary outwards beyond where Rosetta was flying at the time.

Rosetta orbiting comet 67P

"Finding a magnetic field-free region anyway in the Solar System is really hard, but here we've had it served to us on a silver platter – this is a really exciting result for us," adds Charlotte.

“We’ve been moving Rosetta out to distances of up to 300 km in recent weeks to avoid problems with navigation caused by dust, and we had considered that the diamagnetic cavity was out of our grasp for the time being. But it seems that the comet has helped us by bringing the cavity to Rosetta,” says Matt Taylor, Rosetta Project Scientist.

“This is a fantastic multi-instrument event which will take time to analyse, but highlights the exciting times we’re experiencing at the comet in this ‘hot’ perihelion phase.”

Notes for Editors:

A Google+ Hangout celebrating a year at the comet and perihelion is scheduled for 13:00–15:00 GMT (15:00–17:00 CEST) on 13 August. Watch here: https://plus.google.com/events/cl01p03as680jn4iflpp1hmdbr4. (Ask questions in advance on the G+ event page or via Twitter using #AskRosetta).

Learn more about perihelion in Orbiter.ch Space News:

Rosetta: preparing for perihelion: http://orbiterchspacenews.blogspot.ch/2015/07/rosetta-preparing-for-perihelion.html

About Rosetta:

Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander is contributed by a consortium led by DLR, MPS, CNES and ASI.

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

Where is Rosetta?: http://sci.esa.int/where_is_rosetta/

Rosetta overview: http://www.esa.int/Our_Activities/Space_Science/Rosetta_overview

Rosetta in depth:http://sci.esa.int/rosetta

Rosetta factsheet: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_factsheet

Frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions

Images, Graphics, Text, Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA/RPC/IGEP/IC/ROSINA/UBern/ BIRA/LATMOS/LMM/IRAP/MPS/SwRI/TUB/UMich.

Best regards, Orbiter.ch

Charting the Slow Death of the Universe












ESO - European Southern Observatory logo.

11 August 2015

GAMA survey releases first data at IAU General Assembly

An international team of astronomers studying more than 200 000 galaxies has measured the energy generated within a large portion of space more precisely than ever before. This represents the most comprehensive assessment of the energy output of the nearby Universe. They confirm that the energy produced in a section of the Universe today is only about half what it was two billion years ago and find that this fading is occurring across all wavelengths from the ultraviolet to the far infrared. The Universe is slowly dying.

The study involves many of the world’s most powerful telescopes, including ESO's VISTA and VST survey telescopes at the Paranal Observatory in Chile. Supporting observations were made by two orbiting space telescopes operated by NASA (GALEX and WISE) and another belonging to the European Space Agency (Herschel) [1].

The research is part of the Galaxy And Mass Assembly (GAMA) project, the largest multi-wavelength survey ever put together.

Galaxy images from the GAMA survey

“We used as many space and ground-based telescopes as we could get our hands on to measure the energy output of over 200 000 galaxies across as broad a wavelength range as possible,” says Simon Driver (ICRAR, The University of Western Australia), who heads the large GAMA team.

The survey data, released to astronomers around the world today, includes measurements of the energy output of each galaxy at 21 wavelengths, from the ultraviolet to the far infrared. This dataset will help scientists to better understand how different types of galaxies form and evolve.

All the energy in the Universe was created in the Big Bang, with some portion locked up as mass. Stars shine by converting mass back into energy, as described by Einstein’s famous equation E=mc2 [2]. The GAMA study sets out to map and model all of the energy generated within a large volume of space today and at different times in the past.

“While most of the energy sloshing around in the Universe arose in the aftermath of the Big Bang, additional energy is constantly being generated by stars as they fuse elements like hydrogen and helium together,” Simon Driver says. “This new energy is either absorbed by dust as it travels through the host galaxy, or escapes into intergalactic space and travels until it hits something, such as another star, a planet, or, very occasionally, a telescope mirror.”

The fact that the Universe is slowly fading has been known since the late 1990s, but this work shows that it is happening across all wavelengths from the ultraviolet to the infrared, representing the most comprehensive assessment of the energy output of the nearby Universe.

"The Universe will decline from here on in, sliding gently into old age. The Universe has basically sat down on the sofa, pulled up a blanket and is about to nod off for an eternal doze,” concludes Simon Driver.

The team of researchers hope to expand the work to map energy production over the entire history of the Universe, using a swathe of new facilities, including the world’s largest radio telescope, the Square Kilometre Array, which is due to be built in Australia and South Africa over the next decade.

The team will present this work at the International Astronomical Union XXIX General Assembly in Honolulu, Hawaii, on Monday 10 August 2015.

Notes:

[1] The telescopes and survey data used, in order of increasing wavelength, were: GALEX, SDSS, VST (KiDS survey), AAT, VISTA (VIKING survey)/UKIRT, WISE, Herschel (PACS/SPIRE).

[2] Much of the Universe’s energy output comes from nuclear fusion in stars, when mass is slowly converted into energy. Another major source is the very hot discs around black holes at the centres of galaxies, where gravitational energy is converted to electromagnetic radiation in quasars and other active galactic nuclei. Much longer wavelength radiation comes from huge dust clouds that are re-radiating the energy from stars within them.

More information:

This research will be presented in a paper entitled “Galaxy And Mass Assembly (GAMA): Panchromatic Data Release (far-UV—far-IR) and the low-z energy budget”, by S. Driver et al., submitted to the journal Monthly Notices of the Royal Astronomical Society. It will also be the subject of a talk and press event at the IAU General Assembly in Hawaii on 10 August 2015.

The team is composed of Simon P. Driver (ICRAR, The University of Western Australia, Crawley, Western Australia, Australia [ICRAR]; University of St Andrews, United Kingdom), Angus H. Wright (ICRAR), Stephen K. Andrews (ICRAR), Luke J. Davies (ICRAR) , Prajwal R. Kafle (ICRAR), Rebecca Lange (ICRAR), Amanda J. Moffett (ICRAR) , Elizabeth Mannering (ICRAR), Aaron S. G. Robotham (ICRAR), Kevin Vinsen (ICRAR), Mehmet Alpaslan (NASA Ames Research Centre, Mountain View, California, United States), Ellen Andrae (Max Planck Institute for Nuclear Physics, Heidelberg, Germany [MPIK]), Ivan K. Baldry (Liverpool John Moores University, Liverpool, United Kingdom), Amanda E. Bauer (Australian Astronomical Observatory, North Ryde, NSW, Australia [AAO]), Steve Bamford (University of Nottingham, United Kingdom), Joss Bland-Hawthorn (University of Sydney, NSW, Australia), Nathan Bourne (Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), Sarah Brough (AAO), Michael J. I. Brown (Monash University, Clayton, Victoria, Australia), Michelle E. Cluver (The University of Western Cape, Bellville, South Africa), Scott Croom (University of Sydney, NSW, Australia), Matthew Colless (Australian National University, Canberra, ACT, Australia), Christopher J. Conselice (University of Nottingham, United Kingdom), Elisabete da Cunha (Macquarie University, Sydney NSW, Australia), Roberto De Propris (University of Turku, Piikkiö, Finland), Michael Drinkwater (Queensland University of Technology, Brisbane, Queensland, Australia), Loretta Dunne (Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom; Cardiff University, Cardiff, United Kingdom), Steve Eales (Cardiff University, Cardiff, United Kingdom), Alastair Edge (Durham University, Durham, United Kingdom), Carlos Frenk (Durham University, Durham, United Kingdom), Alister W. Graham (Macquarie University, Sydney NSW, Australia), Meiert Grootes (MPIK), Benne W. Holwerda (Leiden Observatory, University of Leiden, Leiden, The Netherlands), Andrew M. Hopkins (AAO) , Edo Ibar (Universidad de Valparaso, Valparaiso, Chile), Eelco van Kampen (ESO, Garching, Germany), Lee S. Kelvin (Liverpool John Moores University, Liverpool, United Kingdom), Tom Jarrett (University of Cape Town, Rondebosch, South Africa), D. Heath Jones (Macquarie University, Sydney, NSW, Australia), Maritza A. Lara-Lopez (Universidad Nacional Automana de México, México), Angel R. Lopez-Sanchez (AAO), Joe Liske (Hamburger Sternwarte, Universität Hamburg, Hamburg, Germany), Jon Loveday (University of Sussex, Falmer, Brighton, United Kingdom), Steve J. Maddox (Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom; Cardiff University, Cardiff, United Kingdom), Barry Madore (Observatories of the Carnegie Institution of Washington, Pasadena, California, United States [OCIW]), Martin Meyer (ICRAR) , Peder Norberg (Durham University, Durham, United Kingdom), Samantha J. Penny (University of Portsmouth, Portsmouth, United Kingdom), Stephen Phillipps (University of Bristol, Bristol, United Kingdom), Cristina Popescu (University of Central Lancashire, Preston, Lancashire), Richard J. Tuffs (MPIK), John A. Peacock (Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), Kevin A.Pimbblet (Monash University, Clayton, Victoria, Australia; University of Hull, Hull, United Kingdom), Kate Rowlands (University of St Andrews, United Kingdom), Anne E. Sansom (University of Central Lancashire, Preston, Lancashire), Mark Seibert (OCIW), Matthew W.L. Smith (Queensland University of Technology, Brisbane, Queensland, Australia), Will J. Sutherland (Queen Mary University London, London, United Kingdom), Edward N. Taylor (The University of Melbourne, Parkville, Victoria, Australia), Elisabetta Valiante (Cardiff University, Cardiff, United Kingdom), Lingyu Wang (Durham University, Durham, United Kingdom; SRON Netherlands Institute for Space Research, Groningen, The Netherlands), Stephen M. Wilkins (University of Sussex, Falmer, Brighton, United Kingdom) and Richard Williams (Liverpool John Moores University, Liverpool, United Kingdom).

The Galaxy and Mass Assembly Survey, or GAMA, is a collaboration involving nearly 100 scientists from more than 30 universities located in Australia, Europe and the United States.

ICRAR is a joint venture between Curtin University and The University of Western Australia with support and funding from the State Government of Western Australia.

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”.

Links:

International Astronomical Union XXIX General Assembly: http://astronomy2015.org/

Galaxy And Mass Assembly (GAMA) project: http://www.gama-survey.org/

Research paper: http://www.eso.org/public/archives/releases/sciencepapers/eso1533/eso1533a.pdf

Photos of VISTA and the VST: http://www.eso.org/public/images/archive/category/surveytelescopes/

Link to video fly-through of GAMA data: http://www.icrar.org/research/the-universe-is-dying

Image, Text, Credits: ESO/ICRAR/GAMA.

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