vendredi 31 octobre 2014

NASA Reveals Mysteries of 'Interstellar' Space












NASA patch.

October 31, 2014


Image above: This enormous mosaic of the Milky Way galaxy from NASA's Wide-field Infrared Survey Explorer, or WISE, shows dozens of dense clouds, called nebulae. Many nebulae seen here are places where new stars are forming, creating bubble like structures that can be dozens to hundreds of light-years in size. Image Credit: NASA.

The new Paramount film "Interstellar" imagines a future where astronauts must find a new planet suitable for human life after climate change destroys the Earth's ability to sustain us. Multiple NASA missions are helping avoid this dystopian future by providing critical data necessary to protect Earth. Yet the cosmos beckons us to explore farther from home, expanding human presence deeper into the solar system and beyond. For thousands of years we've wondered if we could find another home among the stars. We're right on the cusp of answering that question.

If you step outside on a very dark night you may be lucky enough to see many of the 2,000 stars visible to the human eye. They're but a fraction of the billions of stars in our galaxy and the innumerable galaxies surrounding us. Multiple NASA missions are helping us extend humanity's senses and capture starlight to help us better understand our place in the universe.

Largely visible light telescopes like Hubble show us the ancient light permeating the cosmos, leading to groundbreaking discoveries like the accelerating expansion of the universe. Through infrared missions like Spitzer, SOFIA and WISE, we've peered deeply through cosmic dust, into stellar nurseries where gases form new stars. With missions like Chandra, Fermi and NuSTAR, we've detected the death throes of massive stars, which can release enormous energy through supernovas and form the exotic phenomenon of black holes.

Yet it was only in the last few years that we could fully grasp how many other planets there might be beyond our solar system. Some 64 million miles (104 kilometers) from Earth, the Kepler Space Telescope stared at a small window of the sky for four years. As planets passed in front of a star in Kepler's line of view, the spacecraft measured the change in brightness. Kepler was designed to determine the likelihood that other planets orbit stars. Because of the mission, we now know it's possible every star has at least one planet. Solar systems surround us in our galaxy and are strewn throughout the myriad galaxies we see. Though we have not yet found a planet exactly like Earth, the implications of the Kepler findings are staggering—there may very well be many worlds much like our own for future generations to explore.

NASA also is developing its next exoplanet mission, the Transiting Exoplanet Survey Satellite (TESS), which will search 200,000 nearby stars for the presence of Earth-size planets.

As of now, the distance between stars is too great for spacecraft to traverse using existing propulsion. Only one spacecraft is poised to leave the solar system in the near future. Voyager 1, launched in 1977, made the historic entry into interstellar space in August of 2012, reaching the region between stars, filled with material ejected by the death of nearby stars millions of years ago. It won't encounter another star for at least 40,000 years. 

The near-term future of exploration should be cause for much excitement, though, as humans and robotic spacecraft pioneer the path Voyager traveled, deeper into our solar system, where extra-terrestrial life may exist, and where humans could one day thrive.

Life as we know it requires water and heat. On our watery planet, we find life teeming at even the most extreme temperatures. Scientists are eager to know if evidence of microbial life exists on other planets and moons within our reach. On Jupiter's moon Europa, for example, there is a temperate ocean caught between a volcanic core and icy surface. Just as life exists in the dark, hot reaches of Earth's ocean, so too could it exist on Europa, waiting to be discovered. NASA is studying a future mission to the watery moon next decade.


Image above: Called the eXtreme Deep Field, or XDF, image from NASA's Hubble Space Telescope contains about 5,500 galaxies. Some span back 13.2 billion years in time -- nearly to the Big Bang, and are the most distant galaxies ever seen. Image Credit: NASA.

Many scientists question if Earth formed with the water it has now. Comets and asteroid impacts early in the planet's history may have brought the water and help transform our atmosphere. Upcoming missions to capture samples of asteroids, like OSIRIS-REx, could reveal the building blocks of life embedded in the rock, which could lead to new insights about the origins of life.

Perhaps the most enticing target to search for evidence of life, however, is Mars. A fleet of spacecraft on the surface and orbiting Mars have revealed the Red Planet once had conditions suitable for life. While the planet's flowing water and atmosphere have significantly diminished, evidence of past life could still be discovered by future exploration. It could even be a home for future human pioneers.

Martian natural resources like water ice embedded in rock could be extracted to create breathable air, drinkable water, and even components for spacecraft propellant. An ability to live off the land will greatly enable multiple human missions to Mars and forever change the history of humankind.

This Journey to Mars begins aboard the International Space Station where astronauts 250 miles above Earth are learning how to live in space for long durations—key knowledge needed for round trips to Mars, which could take 500 days or more. A new generation of U.S. commercial spacecraft and rockets are supplying the space station and will soon launch astronauts once again from U.S. soil. As these 21st century spaceflight innovations open low-Earth Orbit in new ways, NASA is building the capabilities to send humans farther from Earth than even before. In December, we'll conduct the first flight test of the Orion Spacecraft, which will carry astronauts next decade on missions beyond the moon to an asteroid and Mars, launched on the giant Space Launch System rocket.

Many other missions in the near future will expand the frontier of exploration in our solar system. In 2015, New Horizons will fly by Pluto and see the icy world up close for the first time. In 2016, NASA will launch the InSight mission to Mars and asteroid sample return mission OSIRIS-REx. In 2018, Hubble's successor, the James Webb Space Telescope, will see light from the universe's first stars. In about 2019, we'll launch a robotic spacecraft to capture and redirect an asteroid. In 2020, we'll send a new rover to Mars, to follow in the footsteps of Curiosity, search for ancient Martian life, and pave the way for future human explorers. In 2021, SLS and Orion will launch humans on the first crewed mission of the combined system. In the mid-2020s, astronauts will explore an asteroid redirected to an orbit around the moon, and return home with samples that could hold clues to the origins of the solar system and life on Earth. In doing so, those astronauts will travel farther into the solar system than anyone has ever been.

It's an exciting time as NASA reaches new heights to reveal the unknown and benefit humankind. Be a part of the journey and connect with us at http://www.nasa.gov/connect.

Related links:

Hubble Space Telescope: http://www.nasa.gov/hubble and http://hubblesite.org/ and http://www.spacetelescope.org/

Spitzer: http://www.nasa.gov/spitzer

SOFIA: http://www.nasa.gov/sofia

WISE: http://www.nasa.gov/wise

Chandra X-ray Observatory: http://www.nasa.gov/chandra

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

NuSTAR: http://www.nasa.gov/nustar

Kepler Space Telescope: http://www.nasa.gov/kepler

Transiting Exoplanet Survey Satellite (TESS): http://tess.gsfc.nasa.gov/

Voyager 1: http://www.nasa.gov/voyager

Images (mentioned), Text, Credit: NASA.

Cheers, Orbiter.ch

Tracking a Gigantic Sunspot Across the Sun












NASA - Solar Dynamics Observatory (SDO) patch.

October 31, 2014

An active region on the sun – an area of intense and complex magnetic fields – rotated into view on Oct. 18, 2014. Labeled AR 12192, it soon grew into the largest such region in 24 years, and fired off 10 sizable solar flares as it traversed across the face of the sun. The region was so large it could be seen without a telescope for those looking at the sun with eclipse glasses, as many did during a partial eclipse of the sun on Oct. 23.


Images above: Super sunspot AR2192 produced 10 significant solar flare while traversing the Earth-side of the sun; six X-class and four above M5-class. Image Credit: NASA/SDO.

"Despite all the flares, this region did not produce any significant coronal mass ejections," said Alex Young a solar scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Coronal mass ejections, or CMEs, are giant clouds of solar particles that can affect technology when they reach near-Earth space. "You certainly can have flares without CMEs and vice versa, but most big flares do have CMEs. So we're learning that a big active region doesn't always equal the biggest events."

Such active regions are measured in millionths of a solar hemisphere, where 1 micro-hemisphere, or MH, is about 600,000 square miles. This region topped out at 2,750 MH, making it the 33rd largest region out of approximately 32,000 active regions that have been tracked and measured since 1874. It is the largest sunspot seen since AR 6368, which measured 3,080 MH on Nov. 18, 1990.


Animation above: The largest sunspot since November 1990 is seen traveling across the front of the sun in these images from NASA's SDO, captured Oct. 17-Oct 29, 2014. Image Credit: NASA/SDO.

The largest five active regions ever observed were between 4,000 and more than 6,000 MH and they all appeared between 1946 and 1951.

On the other hand, the region that produced one of the biggest solar flares of all time on Sep. 1, 1859  – in what's known as the Carrington event – wasn't even one of the top 50 at only 2,300 MH.

During its trip across the front of the sun, AR 12192 produced six X-class flares, which are the largest flares, and four strong M-class flares. M-class flares are one tenth as strong as X-class flares. The number provides more information about its strength. An M2 is twice as intense as an M1, an M3 is three times as intense, etc.

video
Fireworks on the Sun

Video above: This movie shows fireworks on the sun as 10 significant flares erupted on the sun from Oct. 19-28, 2014. The graph shows X-ray output from the sun as measured by NOAA’s GOES spacecraft. The X-rays peak in sync with each flare. Image Credit: NASA/SDO/NOAA/GOES.

"Having so many similar flares from the same active region will be a nice case study for people who work on predicting solar flares," said Dean Pesnell, project scientist for NASA's Solar Dynamics Observatory at Goddard. "This is important for one day improving the nation's ability to forecast space weather and protect technology and astronauts in space."

The dates and peak times in EDT of the large solar flares from AR 12192 are as follows:

Oct. 19, 1:01 am:      X1.1

Oct. 21, 9:59 pm:      M8.7

Oct. 22, 10:28 am:    X1.6

Oct. 24, 5:41 pm:      X3.1

Oct. 25, 1:08 pm:      X1.0

Oct. 26, 6:56 am:      X2.0

Oct. 26, 8:34 pm:      M7.1

Oct. 27, 6:09 am:      M6.7

Oct. 27, 10:47 am:    X2.0

Oct. 28, 11:32 pm:    M6.6

AR 12192 rotated onto the far side of the sun on Oct. 30, 2014, however as it evolves, we may see a new version of it rotating back into view in two weeks.

Related Links:

For more on this gigantic sunspot and its flares:
  > http://www.nasa.gov/content/goddard/sdo-observes-largest-sunspot-of-the-solar-cycle/
  > http://www.nasa.gov/content/goddard/sdo-observes-more-flares-erupting-from-giant-sunspot/
  > http://orbiterchspacenews.blogspot.ch/2014/10/one-giant-sunspot-6-substantial-flares.html
  > http://orbiterchspacenews.blogspot.ch/2014/10/second-substantial-flare-in-two-days.html
  > http://orbiterchspacenews.blogspot.ch/2014/10/nasas-sdo-observes-x-class-solar-flare.html

Sunspot AR2192 Flare Family Portrait: http://www.nasa.gov/content/goddard/sunspot-ar2192-flare-family-portrait

Sunspot AR2192 Flare Family Portrait - Unlabeled: http://www.nasa.gov/content/goddard/sunspot-ar2192-flare-family-portrait-unlabeled

Download high resolution media from Oct. 24, 2014: http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=11718

Download high resolution media from Oct. 22, 2014: http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=11717

What does it take to be X-class?: http://www.nasa.gov/mission_pages/sunearth/news/X-class-flares.html

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

Image (mentioned), Video (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Karen C. Fox.

Greetings, Orbiter.ch

Virgin Galactic shuttle crashes











Virgin Galactic logo.

October 31, 2014

SpaceShipTwo space plane crashed Friday late afternoon. The accident left one person dead and one injured, police said.


Image above: The space plane sustained serious damage, while on a test above the Mojave Desert. According to KABC, the accident caused one death and one wounded.

The space plane SpaceShipTwo from Virgin Galactic crashed, says the site information Californian Kern Golden Empire, quoting the director of the Air Base and the Mojave Space Stu Witt. One of the two pilots of the space plane SpaceShipTwo from Virgin Galactic is dead and another is seriously injured, police said Friday.

video
One dead in space plane crash

"There is one dead and one seriously injured was transported to a nearby structure," said Sergeant M. Singer.

"SpaceShipTwo suffered a" flight anomaly, "said Virgin Galactic on Twitter. "The condition of the pilot" is "unknown," said the firm British billionaire Richard Branson.

SpaceShipTwo

"The partner of Virgin Galactic, Scaled Composites company, conducted a test flight of SpaceShipTwo" Friday, said Virgin Galactic on Twitter.

"Grave anomaly"

"During this test, the ship suffered a serious anomaly which has resulted in the loss of SpaceShipTwo," while the plane called "WhiteKnightTwo" (White Knight 2) who had transported hooked under her wings "landed safely," says Virgin.

WhiteKnightTwo carrying SpaceShipTwo

"Our main concern is the status of drivers, unknown at this time," says the space company. "We will work closely with the authorities to determine the cause of the accident," she says.

This ship passengers, whose ambition is to fly tourists to the edge of space, take off from the Mojave Desert at 18:30 local time.

Incident occurred after the separation of SpaceShipTwo

The US Federal Aviation and Aerospace (FAA) for its part, said in a statement that "ground controllers of the space base of the Mojave have lost touch with SpaceShipTwo, a vehicle of experimental space flight."

"The incident happened shortly after separating from his ship WhiteKnightTwo launch vehicle," said FAA investigation into the incident.

The flamboyant Richard Branson, who saw one of the most bitter setbacks in his career, tweeted that his "thoughts were with Virgin Galactic and Scaled Composites" and he would "immediately take a plane to (Mojave Desert) to be with the team."


Images above: SpaceShipTwo to launch a test flight with a new fuel rocket engine, for the moment, the current investigation will tell whether it is responsible for the explosion that undergoes SpaceShipTwo flight shortly after her separation from the WhiteKnightTwo and the rocket engine is started.

Two pilots and six passengers

SpaceShipTwo has two pilots and can carry six passengers. This is the commercial version of SpaceShipOne, the first private space plane that reached the edge of space in 2004.

Hundreds of people have already made reservations for a suborbital flight a few minutes of weightlessness aboard SpaceShipTwo, making an advance payment on the $ 200,000 that is the ticket.

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

Images, Video, Text, Credits: AFP/KABC/Virgin Galactic/Translation: Orbiter.ch Aerospace.

Greetings, Orbiter.ch

Cassini Sees Sunny Seas on Titan












NASA/ESA - Cassini-Huygens Mission to Saturn & Titan patch.

October 31, 2014


Image above: This near-infrared, color view from Cassini shows the sun glinting off of Titan's north polar seas. Image Credit: NASA/JPL-Caltech/Univ. Arizona/Univ. Idaho.

As it soared past Saturn's large moon Titan recently, NASA's Cassini spacecraft caught a glimpse of bright sunlight reflecting off hydrocarbon seas.

In the past, Cassini had captured, separately, views of the polar seas and the sun glinting off them, but this is the first time both have been seen together in the same view.

The image is available at: http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA18432

Also in the image:

-- An arrow-shaped complex of bright methane clouds hovers near Titan's north pole. The clouds could be actively refilling the lakes with rainfall.

-- A "bathtub ring," or bright margin, around Kraken Mare -- the sea containing the reflected sunglint -- indicates that the sea was larger at some point, but evaporation has decreased its size.

Titan's seas are mostly liquid methane and ethane. Before Cassini's arrival at Saturn, scientists suspected that Titan might have bodies of open liquid on its surface. Cassini found only great fields of sand dunes near the equator and lower latitudes, but located lakes and seas near the poles, particularly in the north.

The new view shows Titan in infrared light. It was obtained by Cassini's Visible and Infrared Mapping Spectrometer (VIMS) on Aug. 21.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The VIMS team is based at the University of Arizona in Tucson.

More information about Cassini is available at the following sites:

http://www.nasa.gov/cassini and http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

http://saturn.jpl.nasa.gov

Image (mentioned), Text, Credits: NASA/JPL/Preston Dyches.

Greetings, Orbiter.ch

jeudi 30 octobre 2014

Hubble Sees 'Ghost Light' From Dead Galaxies












NASA - Hubble Space Telescope patch.

October 30, 2014

NASA’s Hubble Space Telescope has picked up the faint, ghostly glow of stars ejected from ancient galaxies that were gravitationally ripped apart several billion years ago. The mayhem happened 4 billion light-years away, inside an immense collection of nearly 500 galaxies nicknamed “Pandora’s Cluster,” also known as Abell 2744.

The scattered stars are no longer bound to any one galaxy, and drift freely between galaxies in the cluster. By observing the light from the orphaned stars, Hubble astronomers have assembled forensic evidence that suggests as many as six galaxies were torn to pieces inside the cluster over a stretch of 6 billion years.


Image above: Massive galaxy cluster Abell 2744, nicknamed Pandora's Cluster, takes on a ghostly look where total starlight has been artificially colored blue in this Hubble view. Image Credit: NASA/ESA/IAC/HFF Team, STScI.

Computer modeling of the gravitational dynamics among galaxies in a cluster suggests that galaxies as big as our Milky Way Galaxy are the likely candidates as the source of the stars. The doomed galaxies would have been pulled apart like taffy if they plunged through the center of a galaxy cluster where gravitational tidal forces are strongest. Astronomers have long hypothesized that the light from scattered stars should be detectable after such galaxies are disassembled. However, the predicted “intracluster” glow of stars is very faint and was therefore a challenge to identify.

“The Hubble data revealing the ghost light are important steps forward in understanding the evolution of galaxy clusters,” said Ignacio Trujillo of The Instituto de Astrofísica de Canarias (IAC), Santa Cruz de Tenerife, Spain. “It is also amazingly beautiful in that we found the telltale glow by utilizing Hubble’s unique capabilities.”

The team estimates that the combined light of about 200 billion outcast stars contributes approximately 10 percent of the cluster’s brightness.

“The results are in good agreement with what has been predicted to happen inside massive galaxy clusters,” said Mireia Montes of the IAC, lead author of the paper published in the Oct. 1 issue of the Astrophysical Journal.

Because these extremely faint stars are brightest at near-infrared wavelengths of light, the team emphasized that this type of observation could only be accomplished with Hubble’s infrared sensitivity to extraordinarily dim light.

Hubble measurements determined that the phantom stars are rich in heavier elements like oxygen, carbon, and nitrogen. This means the scattered stars must be second or third-generation stars enriched with the elements forged in the hearts of the universe’s first-generation stars. Spiral galaxies – like the ones believed to be torn apart -- can sustain ongoing star formation that creates chemically-enriched stars.

video
Hubble orbiting Earth

Weighing more than 4 trillion solar masses, Abell 2744 is a target in the Frontier Fields program. This ambitious three-year effort teams Hubble and NASA’s other Great Observatories to look at select massive galaxy clusters to help astronomers probe the remote universe. Galaxy clusters are so massive that their gravity deflects light passing through them, magnifying, brightening, and distorting light in a phenomenon called gravitational lensing. Astronomers exploit this property of space to use the clusters as a zoom lens to magnify the images of far-more-distant galaxies that otherwise would be too faint to be seen.

Montes’ team used the Hubble data to probe the environment of the foreground cluster itself. There are five other Frontier Fields clusters in the program, and the team plans to look for the eerie “ghost light” in these clusters, too.

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

For images and more information about Hubble, visit: http://www.nasa.gov/hubble

http://hubblesite.org/ and http://www.spacetelescope.org/

Image (mentioned), Video, Text, Credits: NASA/Space Telescope Science Institute/Ray Villard/ESA.

Best regards, Orbiter.ch

2014 Antarctic Ozone Hole Holds Steady









NASA - EOS AURA Mission patch.

October 30, 2014

The Antarctic ozone hole reached its annual peak size on Sept. 11, according to scientists from NASA and the National Oceanic and Atmospheric Administration (NOAA). The size of this year’s hole was 24.1 million square kilometers (9.3 million square miles) — an area roughly the size of North America.


Image above: This image shows ozone concentrations above Antarctica on Sept. 11, 2014. Image Credit: NASA.

The single-day maximum area was similar to that in 2013, which reached 24.0 million square kilometers (9.3 million square miles). The largest single-day ozone hole ever recorded by satellite was 29.9 million square kilometers (11.5 million square miles) on Sept. 9, 2000. Overall, the 2014 ozone hole is smaller than the large holes of the 1998–2006 period, and is comparable to 2010, 2012, and 2013.

With the increased atmospheric chlorine levels present since the 1980s, the Antarctic ozone hole forms and expands during the Southern Hemisphere spring (August and September). The ozone layer helps shield life on Earth from potentially harmful ultraviolet radiation that can cause skin cancer and damage plants.

The Montreal Protocol agreement beginning in 1987 regulated ozone depleting substances, such as chlorine-containing chlorofluorocarbons and bromine-containing halons. The 2014 level of these substances over Antarctica has declined about 9 percent below the record maximum in 2000.

“Year-to-year weather variability significantly impacts Antarctica ozone because warmer stratospheric temperatures can reduce ozone depletion,” said Paul A. Newman, chief scientist for atmospheres at NASA's Goddard Space Flight Center in Greenbelt, Maryland. “The ozone hole area is smaller than what we saw in the late-1990s and early 2000s, and we know that chlorine levels are decreasing. However, we are still uncertain about whether a long-term Antarctic stratospheric temperature warming might be reducing this ozone depletion.”

Scientists are working to determine if the ozone hole trend over the last decade is a result of temperature increases or chorine declines. An increase of stratospheric temperature over Antarctica would decrease the ozone hole’s area. Satellite and ground-based measurements show that chlorine levels are declining, but stratospheric temperature analyses in that region are less reliable for determining long-term trends.

Scientists also found that the minimum thickness of ozone layer this year was recorded at 114 Dobson units on Sept. 30, compared to 250-350 Dobson units during the 1960s. Over the last 50 years satellite and ground-based records over Antarctica show ozone column amounts ranging from 100 to 400 Dobson units, which translates to about 1 millimeter (1/25 inch) to 5 millimeters (1/6 inch) of ozone in a layer if all of the ozone were brought down to the surface.


Image above: This image shows ozone concentrations above Antarctica on Sept. 30, 2014. Image Credit: NASA.

The ozone data come from the Dutch-Finnish Ozone Monitoring Instrument on NASA’s Aura satellite and the Ozone Monitoring and Profiler Suite instrument on the NASA-NOAA Suomi National Polar-orbiting Partnership satellite. NOAA measurements at South Pole station monitor the ozone layer above that location by means of Dobson spectrophotometer and regular ozone-sonde balloon launches that record the thickness of the ozone layer and its vertical distribution. Chlorine amounts are estimated using NOAA and NASA ground measurements and observations from the Microwave Limb Sounder aboard NASA’s Aura satellite.

NASA and NOAA are mandated under the Clean Air Act to monitor ozone-depleting gases and stratospheric depletion of ozone. Scientists from NASA and NOAA have been monitoring the ozone layer and the concentrations of ozone-depleting substances and their breakdown products from the ground and with a variety of instruments on satellites and balloons since the 1970s. These observations allow us to provide a continuous long-term record to track the long-term and year-to-year evolution of ozone amounts.

Related Link:

NASA's Ozone Hole Watch website: http://ozonewatch.gsfc.nasa.gov/

Image (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Audrey Haar.

Greetings, Orbiter.ch

Fifteen Years of NASA's Chandra X-ray Observatory












NASA - Chandra X-ray Observatory patch.

October 30, 2014

Hydra A galaxy cluster

This Chandra X-ray Observatory image of the Hydra A galaxy cluster was taken on Oct. 30, 1999, with the Advanced CCD Imaging Spectrometer (ACIS) in an observation that lasted about six hours. Hydra A is a galaxy cluster that is 840 million light years from Earth. The cluster gets its name from the strong radio source, Hydra A, that originates in a galaxy near the center of the cluster. Optical observations show a few hundred galaxies in the cluster. Chandra X-ray observations reveal a large cloud of hot gas that extends throughout the cluster. The gas cloud is several million light years across and has a temperature of about 40 million degrees in the outer parts decreasing to about 35 million degrees in the inner region.

Chandra X-ray Observatory spacecraft

NASA's Chandra X-ray Observatory was launched into space fifteen years ago aboard the Space Shuttle Columbia. Since its deployment on July 23, 1999, Chandra has helped revolutionize our understanding of the universe through its unrivaled X-ray vision. Chandra, one of NASA's current "Great Observatories," along with the Hubble Space Telescope and Spitzer Space Telescope, is specially designed to detect X-ray emission from hot and energetic regions of the universe.

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

Additional information on Chandra and the 15th anniversary can be found at: http://chandra.si.edu/15th

Images, Text, Credits:  Credit: NASA/CXC/SAO.

Cheers, Orbiter.ch

Steering ESA satellites clear of space debris












Space Debris logo / ESA logo.

30 October 2014

Improved collision warnings for its Earth observation missions means ESA controllers can now take more efficient evasive action when satellites are threatened by space junk.

ESA signed an agreement today with the US Strategic Command to improve data exchange between the organisations for supporting missions.

ESA control room

The tie-up will see ESA receiving higher quality and more timely space information tailored to its needs in exchange for sharing more accurate positional information of its satellites.

Engineers at ESA’s Space Operations Centre, ESOC, in Darmstadt, Germany, currently control five satellites in low orbits and expect six more to join them in the next few years.

Improving operation

“The agreement improves ESA’s operations in low orbital altitudes, an environment that is contaminated with numerous pieces of debris from recent fragmentation, at a time when we are about to significantly increase the number of active missions in this orbit,” said ESA Director General Jean-Jacques Dordain.

“The more timely and customisable data exchange enabled by this agreement will improve collision avoidance as well as launch and early operations for our missions.”

CryoSat-2

ESA have already been receiving US data and predictions on possible ‘conjunctions’ for some time, but could not request customised data.

Time-critical scenarios

Under the new arrangement, ESA can request specific surveillance information and receive it in a timely manner.

“We will now get clearly defined data upon requests we submit to the US Joint Space Operations Centre at Vandenberg Air Force Base, California. We also look forward to faster responses,” says Holger Krag, Head of ESA’s Space Debris Office.

US warning centre

“In time-critical scenarios like a degraded orbit injection after launch or sudden loss of contact with one of our missions, there will be fewer formalities and shorter time until we get the data we’d like.”

With earlier warning of potential close calls, controllers will be able to plan avoidance manoeuvres at the working level better. This will reduce the workload and allow collision avoidance manoeuvres to be merged with other, routine manoeuvres, cutting fuel usage.

Enhancing sustainability

“As more countries, companies and organisations field space capabilities and benefit from the use of space systems, it is in our collective interest to act responsibly, to promote transparency and to enhance the long-term sustainability, stability, safety and security of the space joint operating area,” said Admiral Cecil D. Haney, head of US Strategic Command.

In exchange for the improved service from the US side, ESA will provide information on planned orbit manoeuvres, which will allow fine-tuning of the US surveillance approach. This, in turn, will generate more accurate and updated information for ESA.

The more timely and customisable data exchange will improve collision avoidance as well as launch and early orbit operations by ESA.

ESA missions today perform four to six debris avoidance manoeuvres each year, and this number has been increasing: http://blogs.esa.int/atv/2014/10/27/atv-5-pushes-station-out-of-way-of-debris/

The latest conducted by ESOC was performed by CryoSat-2 on 7 October, to avoid a fragment of Cosmos-2251, which collided with Iridium-33 in 2009.

“The predicted flyby distance was just 121 m, which is within the uncertainties of our orbit knowledge – so we had to get further away,” says Holger.

Related links:

Space Debris: http://www.esa.int/Our_Activities/Operations/Space_Debris

USSTRATCOM: http://www.stratcom.mil/

Webcast: Concluding press conference 6th European Conference on Space Debris:
http://www.esa.int/Our_Activities/Operations/Space_Debris/Webcast_Concluding_press_conference_6th_European_Conference_on_Space_Debris

Images, Text, Credits: ESA/J. Mai/P. Carril/US Air Force photo/Airman 1st Class Antoinette Lyons.

Greetings, Orbiter.ch

mercredi 29 octobre 2014

Progress Cargo Craft Docks to Space Station











ROSCOSMOS - Russian Vehicle patch.

October 29, 2014

video
 Progress M-25M docking with the ISS

Traveling about 261 miles over the Atlantic Ocean, the unpiloted ISS Progress 57 Russian cargo ship docked at 9:08 a.m. EDT to the Pirs Docking Compartment of the International Space Station.


Image above: The ISS Progress 57 is moments from docking to the Pirs Docking Compartment of the International Space Station. Image Credit: NASA TV.

The craft is delivering almost three tons of food, fuel and supplies, including 1,940 pounds of propellant; 48 pounds of oxygen; 57 pounds of air; 926 pounds of water; and 2,822 pounds of spare parts, supplies and experiment hardware for the six members of the Expedition 41 crew currently living and working in space. Progress 57 is scheduled to remain docked to Pirs for the next six months.

For more information about the current crew and the International Space Station, visit: http://www.nasa.gov/station.

Image (mentioned), Video, Text, Credit: NASA / NASA TV.

Cheers, Orbiter.ch

United Launch Alliance Successfully Launches 50th Atlas V Rocket















ULA - Atlas V & GPS IIF-8 Mission poster.


Oct. 29, 2014

Fourth Global Positioning System Satellite Launched for the Air Force in 2014

Atlas V 401 rocket carrying GPS IIF-8 satellite launch

An American Atlas V 401 rocket successfully launched today, October 29th 2014, at 17:21 UTC carrying the GPS IIF-8 satellite into orbit for the US Air Force. The Atlas V 401 rocket was the 50th launch of an Atlas V vehicle. This is ULA’s 12th launch in 2014, and the 89th successful launch since the company was formed in December 2006.

“ULA is honored to work with this world-class U.S. government and contractor mission team, and we are very proud to have delivered  the GPS IIF-8 satellite to orbit today on the 50th Atlas V mission,” said Jim Sponnick, ULA vice president, Atlas and Delta Programs. “Achieving 50 Atlas missions with 100 percent mission success is a tribute to this team’s sustained focus on one mission at a time and dedication to reliably meeting our customer’s launch needs.”

video
Launch of GPS IIF-8 on Atlas V Rocket from Cape

This mission was launched aboard an Atlas V Evolved Expendable Launch Vehicle (EELV) 401 configuration vehicle, which includes a 4-meter-diameter payload fairing. The Atlas booster for this mission was powered by the RD AMROSS RD-180 engine, and the Centaur upper stage was powered by a single Aerojet Rocketdyne RL10A engine.

ULA's next launch is the Delta IV Heavy Exploration Flight Test (EFT-1) mission of NASA’s Orion spacecraft for Lockheed Martin scheduled for Dec. 4 from Space Launch Complex-37 at Cape Canaveral Air Force Station, Florida.

GPS IIF-8 is the eighth in a series of next generation GPS satellites and will join a worldwide timing and navigation system utilizing 24 satellites in six different planes, with a minimum of four satellites per plane positioned in orbit approximately 11,000 miles above the Earth’s surface. The GPS IIF series provides improved accuracy and enhanced performance for GPS users.

GPS IIF satellite

The EELV program was established by the United States Air Force to provide assured access to space for Department of Defense and other government payloads. The commercially developed EELV program supports the full range of government mission requirements, while delivering on schedule and providing significant cost savings over the heritage launch systems. 

With more than a century of combined heritage, United Launch Alliance is the nation’s most experienced and reliable launch service provider. ULA has successfully delivered more than 85 satellites to orbit that provide critical capabilities for troops in the field, aid meteorologists in tracking severe weather, enable personal device-based GPS navigation and unlock the mysteries of our solar system.

For more information on ULA, visit the ULA website at http://www.ulalaunch.com.  Join the conversation at http://www.facebook.com/ulalaunch, http://twitter.com/ulalaunch and http://instagram.com/ulalaunch.

Images, Video, Text, Credits: ULA / Gunter Space Page.

Greetings, Orbiter.ch

Planet-forming Lifeline Discovered in a Binary Star System















ESO - European Southern Observatory logo / ALMA - Atacama Large Millimeter/submillimeter Array logo.

29 October 2014

ALMA Examines Ezekiel-like “Wheel in a Wheel” of Dust and Gas

Artist’s impression of the double-star system GG Tauri-A

For the first time, researchers using ALMA have detected a streamer of gas flowing from a massive outer disc toward the inner reaches of a binary star system. This never-before-seen feature may be responsible for sustaining a second, smaller disc of planet-forming material that otherwise would have disappeared long ago. Half of Sun-like stars are born in binary systems, meaning that these findings will have major consequences for the hunt for exoplanets. The results are published in the journal Nature on 30 October 2014.

A research group led by Anne Dutrey from the Laboratory of Astrophysics of Bordeaux, France and CNRS used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the distribution of dust and gas in a multiple-star system called GG Tau-A [1]. This object is only a few million years old and lies about 450 light-years from Earth in the constellation of Taurus (The Bull).

View of the sky around the multiple star system GG Tauri

Like a wheel in a wheel, GG Tau-A contains a large, outer disc encircling the entire system as well as an inner disc around the main central star. This second inner disc has a mass roughly equivalent to that of Jupiter. Its presence has been an intriguing mystery for astronomers since it is losing material to its central star at a rate that should have depleted it long ago.

While observing these structures with ALMA, the team made the exciting discovery of gas clumps in the region between the two discs. The new observations suggest that material is being transferred from the outer to the inner disc, creating a sustaining lifeline between the two [2].

“Material flowing through the cavity was predicted by computer simulations but has not been imaged before. Detecting these clumps indicates that material is moving between the discs, allowing one to feed off the other,” explains Dutrey. “These observations demonstrate that material from the outer disc can sustain the inner disc for a long time. This has major consequences for potential planet formation.”

video
Artist’s impression of the double-star system GG Tauri-A

Planets are born from the material left over from star birth. This is a slow process, meaning that an enduring disc is a prerequisite for planet formation. If the feeding process into the inner disc now seen with ALMA occurs in other multiple-star systems the findings introduce a vast number of new potential locations to find exoplanets in the future.

The first phase of exoplanet searches was directed at single-host stars like the Sun [3]. More recently it has been shown that a large fraction of giant planets orbit binary-star systems. Now, researchers have begun to take an even closer look and investigate the possibility of planets orbiting the individual stars of multiple-star systems. The new discovery supports the possible existence of such planets, giving exoplanet discoverers new happy hunting grounds.

Emmanuel Di Folco, co-author of the paper, concludes: “Almost half the Sun-like stars were born in binary systems. This means that we have found a mechanism to sustain planet formation that applies to a significant number of stars in the Milky Way. Our observations are a big step forward in truly understanding planet formation.”

Notes:

[1] GG Tau-A is part of a more complex multiple-star system called GG Tauri. Recent observations of GG Tau-A using the VLTI have revealed that one of the stars — GG Tau Ab, the one not surrounded by a disc — is itself a close binary, consisting of GG Tau-Ab1 and GG Tau-Ab2. This introduced a fifth component to the GG Tau system.

[2] An earlier result with ALMA showed an example of a single star with material flowing inwards from the outer part of its disc.

[3] Because orbits in binary stars are more complex and less stable, it was believed that forming planets in these systems would be more challenging than around single stars.

More information:

This research was presented in a paper entitled “Planet formation in the young, low-mass multiple stellar system GG Tau-A” by A. Dutrey et al., to appear in the journal Nature.

The team is composed of Anne Dutrey (University Bordeaux/CNRS, France), Emmanuel Di Folco (University Bordeaux/CNRS), Stephane Guilloteau (University Bordeaux/CNRS), Yann Boehler (University of Mexico, Michoacan, Mexico), Jeff Bary (Colgate University, Hamilton, USA), Tracy Beck (Space Telescope Science Institute, Baltimore, USA), Hervé Beust (IPAG, Grenoble, France), Edwige Chapillon (University Bordeaux/IRAM, France), Fredéric Gueth (IRAM, Saint Martin d’Hères, France), Jean-Marc Huré (University Bordeaux/CNRS), Arnaud Pierens (University Bordeaux/CNRS), Vincent Piétu (IRAM), Michal Simon (Stony Brook University, USA) and Ya-Wen Tang (Academia Sinica Institute of Astronomy and Astrophysics, Taipei, Taiwan).

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Southern Observatory (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). 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 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links:

Research paper: http://www.eso.org/public/archives/releases/sciencepapers/eso1434/eso1434a.pdf

More about ALMA: http://www.eso.org/public/teles-instr/alma/

Photos of ALMA: http://www.eso.org/public/images/archive/category/alma/

Videos of ALMA: http://www.eso.org/public/videos/archive/category/alma/

ALMA brochure: http://www.eso.org/public/products/brochures/brochure_0018/

The movie ALMA — In Search of our Cosmic Origins: http://www.eso.org/public/videos/eso1312a/

The ALMA Photo Book In Search of our Cosmic Origins – The Construction of the Atacama Large Millimeter/submillimeter Array: http://www.eso.org/public/products/books/book_0052/

More press releases with ALMA: http://www.eso.org/public/news/archive/search/?adv=&facility=36

Images, Tex, Credits: ESO/L. Calçada/Digitized Sky Survey 2. Acknowledgement: Davide De Martin/Video: ESO/L. Calçada. Music: movetwo.

Best regards, Orbiter.ch

Progress Cargo Craft on Way to Station











ROSCOSMOS - Russian Vehicles patch.

October 29, 2014


Image above: The ISS Progress 57 space freighter launches on time from Kazakhstan for a six-hour trip to the International Space Station.

Carrying more than 5,700 pounds of food, fuel, and supplies for the International Space Station crew, the unpiloted ISS Progress 57 cargo craft launched at 3:09 a.m. EDT (1:09 p.m. local time in Baikonur) from the Baikonur Cosmodrome in Kazakhstan.

video
Liftoff Soyuz 2.1a with Progress M-25M

At the time of launch, the International Space Station was flying about 261 miles over southern Russia, just north of the border with Kazakhstan.

Less than 10 minutes after launch, the resupply ship reached preliminary orbit and deployed its solar arrays and navigational antennas as planned. The Russian cargo craft will make four orbits of Earth during the next six hours before docking to the orbiting laboratory at 9:09 a.m.

Beginning at 8:30 a.m., NASA Television will provide live coverage of Progress 57′s arrival to the space station’s Pirs Docking Compartment. Watch live on NASA TV and online at http://www.nasa.gov/nasatv

To join the online conversation about the International Space Station and Progress 57 on Twitter, follow the hashtags #ISS and #ISScargo.

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

Image, Video, Text, Credits: NASA / Roscosmos TV.

Greetings, Orbiter.ch

mardi 28 octobre 2014

Antares Rocket Explodes after Liftoff, Orb-3 mission failed












Orbital - Antares & CRS Cygnus Orb-3 Mission patch.

October 28, 2014

An Orbital Sciences Corp. Antares rocket carrying a Cygnus cargo spacecraft on a mission to the international space station exploded seconds after liftoff Oct. 28.

Antares rocket carrying a Cygnus cargo spacecraft explosion on the ground

The Antares rocket lifted off on schedule at 6:22 pm EDT from the Mid-Atlantic Regional Spaceport at Wallops Island, Virginia. Approximately ten seconds after liftoff, however, an explosion took place at the base of the rocket’s first stage. The rocket fell back to the ground near the launch pad, triggering a second, larger explosion.

video
Antares Rocket Launch Failure Carrying Cygnus cargo spacecraft

No injuries were reported in the launch failure, according to NASA TV commentary. Initial reports did indicate damage to the launch pad at Wallops.

The accident, the first launch failure in five Antares launches, took place after a problem-free countdown. The launch was originally scheduled for Oct. 27 but was scrubbed when a boat entered restricted waters off the coast from the launch site and did not leave before the ten-minute launch window closed.

Probable damage to the launch pad at Wallops

The mission, designated Orb-3 by NASA, was the third of eight Commercial Resupply Services missions that Orbital Sciences is under contract to perform for the space agency. The Cygnus, named by Orbital the “SS Deke Slayton” after the late astronaut, was carrying 2,290 kilograms of cargo for the station.

ORBITAL’S STATEMENT REGARDING ORB-3 LAUNCH MISHAP

Orbital Sciences Corporation confirms that today’s Antares rocket launch from NASA’s Wallops Flight Facility was not successful. Shortly after lift-off from the Mid-Atlantic Regional Spaceport Pad 0A at 6:22 p.m. (EDT), the vehicle suffered a catastrophic failure. According to NASA’s emergency operations officials, there were no casualties and property damage was limited to the south end of Wallops Island. Orbital has formed an anomaly investigation board, which will work in close coordination with all appropriate government agencies, to determine the cause of today’s mishap.

“It is far too early to know the details of what happened,” said Mr. Frank Culbertson, Orbital’s Executive Vice President and General Manager of its Advanced Programs Group.“As we begin to gather information, our primary concern lies with the ongoing safety and security of those involved in our response and recovery operations. We will conduct a thorough investigation immediately to determine the cause of this failure and what steps can be taken to avoid a repeat of this incident. As soon as we understand the cause we will begin the necessary work to return to flight to support our customers and the nation’s space program.”

Orbital will provide more information as it becomes available and is verified.

For more information about Orbital: http://www.orbital.com/

Images, Video, Text, Credits: Orbital / NASA / NASA TV / Orbiter.ch Aerospace.

NASA’s LRO Spacecraft Captures Images of LADEE’s Impact Crater














NASA - Lunar Reconnaissance Orbiter (LRO) patch / NASA - LADEE Mission patch.

October 28, 2014

Before and After Images: 

Before LADEE impact

After LADEE impact

Images above: These images show the area of the LADEE impact before and after spacecraft's planned impact into the eastern rim of Sundman V crater. Image Credit: NASA/Goddard/Arizona State University.

NASA’S Lunar Reconnaissance Orbiter (LRO) spacecraft has spied a new crater on the lunar surface; one made from the impact of NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) mission.

“The Lunar Reconnaissance Orbiter Camera (LROC) team recently developed a new computer tool to search Narrow Angle Camera (NAC) before and after image pairs for new craters, the LADEE impact event provided a fun test, said Mark Robinson, LROC principal investigator from Arizona State University in Tempe. “As it turns there were several small surface changes found in the predicted area of the impact, the biggest and most distinctive was within 968 feet (295 meters) of the spot estimated by the LADEE operations team. What fun!”

The LADEE mission ended on April 18, 2014, with the spacecraft’s planned impact into the eastern rim of Sundman V crater on the far side of the moon.

LADEE's engines fired April 11, 2014, to perform a final orbital maintenance maneuver and adjust to guarantee it would impact on the farside of the moon and away from the Apollo landing sites. Over a seven-day period, LADEE's orbit decreased and the spacecraft orbited very low to the surface and close to the walls of lunar craters and mountain ridges to give the team a chance to collect valuable science data. Finally, LADEE impacted the eastern rim of Sundman V crater on April 18. The impact site is about half a mile (780 meters) from the crater rim with an altitude of about 8,497 feet (2,590 meters) and was only about two tenths of a mile (300 meters) north of the location mission controllers predicted based on tracking data.


Image above: LRO has imaged the LADEE impact site on the eastern rim of Sundman V crater. The image was created by ratioing two images, one taken before the impact and another afterwards. The bright area highlights what has changed between the time of the two images, specifically the impact point and the ejecta. Image Credit: NASA/Goddard/Arizona State University.

The impact crater is small, less than ten feet (three meters) in diameter, barely resolvable by the LROC NAC. The crater is small because the spacecraft -- compared to most celestial impacts -- was not traveling very fast, approximately 3,800 miles per hour (1,699 meters per second) and had a low mass and a low density. The size of the impact crater made it hard to identify among the myriad of small fresh craters on the lunar surface. Images acquired of the impact region before the impact, were compared with images obtained after the impact to identify the crater.

Since the NAC images are so large (250 mega-pixels) and the new crater is so small, the LROC team co-registered the before and after images (called a temporal pair) and then divided the before image by the after image. By doing this, changes to the surface become evident.

The ejecta from the impact forms a triangular pattern primarily downrange to the west, extending about 656-984 feet (200-300 meters) from the impact site. There is also a small triangular area of ejecta up range but it extends only about 66-98 feet (20-30 meters). The ejecta pattern is oriented northwest, consistent with the direction the spacecraft was traveling when it impacted the surface.


Image above: Artist concept of the Lunar Reconnaissance Orbiter with Apollo mission imagery of the moon in the background. Image Credit: NASA's Goddard Space Flight Center.

"I'm happy that the LROC team was able to confirm the LADEE impact point," said Butler Hine, LADEE project manager at Ames Research Center in Moffett Field, California. "It really helps the LADEE team to get closure and know exactly where the product of their hard work wound up."

LADEE launched Sept. 6, 2013 from Pad 0B at the Mid-Atlantic Regional Spaceport, at NASA's Wallops Flight Facility, Wallops Island, Virginia. LADEE gathered detailed information about the structure and composition of the thin lunar atmosphere and determining whether dust is being lofted into the lunar sky.

LRO launched September 18, 2009. LRO continues to bring the world astounding views of the lunar surface and a sizable collection of lunar data for research.


Image above: An artist's concept of NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft seen orbiting near the surface of the moon. Image Credit: NASA Ames/Dana Berry.

LRO recently received a second two-year extended mission. Under the extended mission, LRO will study the seasonal volatile cycle; determine how many small meteorites are currently hitting the moon and their effects; characterize the structure of the lunar regolith; investigate the moon’s interaction with the space environment; and reveal more about the lunar interior using observations of the moon’s surface.

“With LRO, NASA will study our nearest celestial neighbor for at least two more years,” said John Keller, LRO project scientist from NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “LRO continues to increase our understanding of the moon and its environment.”

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the LRO mission. NASA's Ames Research Center in Moffett Field, California, designed, built, tested and managed operations for the LADEE mission.

For information on LRO, visit: http://www.nasa.gov/lro

For more information on LROC, visit: http://lroc.sese.asu.edu

For more information about LADEE mission, visit: http://www.nasa.gov/mission_pages/ladee/main/

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

Greetings, Orbiter.ch

lundi 27 octobre 2014

Chandra Observatory Identifies Impact of Cosmic Chaos on Star Birth












NASA - Chandra X-ray Observatory patch.

October 27, 2014


Image above: Chandra observations of the Perseus and Virgo galaxy clusters suggest turbulence may be preventing hot gas there from cooling, addressing a long-standing question of galaxy clusters do not form large numbers of stars. Image Credit: NASA/CXC/Stanford/I. Zhuravleva et al.

The same phenomenon that causes a bumpy airplane ride, turbulence, may be the solution to a long-standing mystery about stars’ birth, or the absence of it, according to a new study using data from NASA’s Chandra X-ray Observatory.

Galaxy clusters are the largest objects in the universe, held together by gravity.  These behemoths contain hundreds or thousands of individual galaxies that are immersed in gas with temperatures of millions of degrees.

This hot gas, which is the heftiest component of the galaxy clusters aside from unseen dark matter, glows brightly in X-ray light detected by Chandra. Over time, the gas in the centers of these clusters should cool enough that stars form at prodigious rates. However, this is not what astronomers have observed in many galaxy clusters.

“We knew that somehow the gas in clusters is being heated to prevent it cooling and forming stars. The question was exactly how,” said Irina Zhuravleva of Stanford University in Palo Alto, California, who led the study that appears in the latest online issue of the journal Nature. “We think we may have found evidence that the heat is channeled from turbulent motions, which we identify from signatures recorded in X-ray images.”

Prior studies show supermassive black holes, centered in large galaxies in the middle of galaxy clusters, pump vast quantities of energy around them in powerful jets of energetic particles that create cavities in the hot gas. Chandra, and other X-ray telescopes, have detected these giant cavities before.

The latest research by Zhuravleva and her colleagues provides new insight into how energy can be transferred from these cavities to the surrounding gas. The interaction of the cavities with the gas may be generating turbulence, or chaotic motion, which then disperses to keep the gas hot for billions of years.

“Any gas motions from the turbulence will eventually decay, releasing their energy to the gas,” said co-author Eugene Churazov of the Max Planck Institute for Astrophysics in Munich, Germany. “But the gas won’t cool if turbulence is strong enough and generated often enough.”

The evidence for turbulence comes from Chandra data on two enormous galaxy clusters named Perseus and Virgo. By analyzing extended observation data of each cluster, the team was able to measure fluctuations in the density of the gas. This information allowed them to estimate the amount of turbulence in the gas.

Chandra X-ray Observatory spacecraft. Image Credit: NASA/CXC

“Our work gives us an estimate of how much turbulence is generated in these clusters,” said Alexander Schekochihin of the University of Oxford in the United Kingdom. “From what we’ve determined so far, there’s enough turbulence to balance the cooling of the gas.

These results support the “feedback” model involving supermassive black holes in the centers of galaxy clusters. Gas cools and falls toward the black hole at an accelerating rate, causing the black hole to increase the output of its jets, which produce cavities and drive the turbulence in the gas. This turbulence eventually dissipates and heats the gas.

While a merger between two galaxy clusters may also produce turbulence, the researchers think that outbursts from supermassive black holes are the main source of this cosmic commotion in the dense centers of many clusters.

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, controls Chandra's science and flight operations.

An interactive image, podcast, and video about these 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 / Marshall Space Flight Center / Janet Anderson / Chandra X-ray Center / Megan Watzke.

Greetings, Orbiter.ch