jeudi 12 février 2015

Exploded Star Blooms Like a Cosmic Flower












NASA - Chandra X-ray Observatory patch.

February 11, 2015

Because the debris fields of exploded stars, known as supernova remnants, are very hot, energetic, and glow brightly in X-ray light, NASA’s Chandra X-ray Observatory has proven to be a valuable tool in studying them. The supernova remnant called G299.2-2.9 (or G299 for short) is located within our Milky Way galaxy, but Chandra’s new image of it is reminiscent of a beautiful flower here on Earth.


Image above: Chandra observations of the supernova remnant G299.2-2.9 reveal important information about this object. Image Credit: NASA/CXC/U.Texas.

G299 was left over by a particular class of supernovas called Type Ia.  Astronomers think that a Type Ia supernova is a thermonuclear explosion – involving the fusion of elements and release of vast amounts of energy − of a white dwarf star in a tight orbit with a companion star. If the white dwarf’s partner is a typical, Sun-like star, the white dwarf can become unstable and explode as it draws material from its companion. Alternatively, the white dwarf is in orbit with another white dwarf, the two may merge and can trigger an explosion.

Regardless of their triggering mechanism, Type Ia supernovas have long been known to be uniform in their extreme brightness, usually outshining the entire galaxy where they are found. This is important because scientists use these objects as cosmic mileposts, allowing them to accurately measure the distances of galaxies billions of light years away, and to determine the rate of expansion of the Universe.

Traditional theoretical models of Type Ia supernovas generally predict that these explosions would be symmetric, creating a near perfect sphere as they expand. These models have been supported by results showing that remnants of Type Ia supernovas are more symmetric than remnants of supernovas involving the collapse of massive stars.

However, astronomers are discovering that some Type Ia supernova explosions may not be as symmetric as previously thought. G299 could be an example of such an “unusual” Type Ia supernova. Using a long observation from Chandra, researchers discovered the shell of debris from the exploded star is expanding differently in various directions.

In this new Chandra image, red, green, and blue represent low, medium, and high-energy X-rays, respectively, detected by the telescope. The medium energy X-rays include emission from iron and the hard-energy X-rays include emission from silicon and sulfur. The X-ray data have been combined with infrared data from ground-based 2MASS survey that shows the stars in the field of view.

By performing a detailed analysis of the X-rays, researchers found several clear examples of asymmetry in G299. For example, the ratio between the amounts of iron and silicon in the part of the remnant just above the center is larger than in the part of the remnant just below the center. This difference can be seen in the greener color of the upper region compared to the bluer color of the lower region. Also, there is a strongly elongated portion of the remnant extending to the right. In this region, the relative amount of iron to silicon is similar to that found in the southern region of the remnant.

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

The patterns seen in the Chandra data suggest that a very lopsided explosion may have produced this Type Ia supernova. It might also be that the remnant has been expanding into an environment where the medium it encountered was uneven. Regardless of the ultimate explanation, observations of G299 and others like it are showing astronomers just how varied such beautiful cosmic flowers can be.

A paper describing these results was published in the September 1st, 2014 issue of The Astrophysical Journal, and is available online (http://arxiv.org/abs/1406.2190). The authors are Seth Post and Sangwook Park from the University of Texas at Arlington in Texas; Carles Badenes from the University of Pittsburgh, in Pittsburgh, Pennsylvania; David Burrows from Pennsylvania State University in University Park, Pennsylvania.

John Hughes from Rutgers University in Piscataway, New Jersey; Jae-Joon Lee from the Korea Astronomy and Space Science Institute; Koji Mori from the University of Miyazaki in Japan and Patrick Slane from the Harvard-Smithsonian Center of Astrophysics in Cambridge, Massachusetts.

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.

For more information about Chandra X-ray Observatory mission, visit: http://www.nasa.gov/mission_pages/chandra/main/

Images (mentioned), Text, Credits: NASA/Marshall Space Flight Center/Janet Anderson/Chandra X-ray Center/Megan Watzke.

Greetings, Orbiter.ch

The View from New Horizons: A Full Day on Pluto-Charon












NASA - New Horizons logo.

February 12, 2015


Animation above: This time-lapse “movie” of Pluto and its largest moon, Charon, was recently shot at record-setting distances with the Long-Range Reconnaissance Imager (LORRI) on NASA’s New Horizons spacecraft. Image Credit: NASA/APL/Southwest Research Institute.

This time-lapse “movie” of Pluto and its largest moon, Charon, was recently shot at record-setting distances with the Long-Range Reconnaissance Imager (LORRI) on NASA’s New Horizons spacecraft. The movie was made over about a week, from Jan. 25-31, 2015. It was taken as part of the mission’s second optical navigation (“OpNav”) campaign to better refine the locations of Pluto and Charon in preparation for the spacecraft’s close encounter with the small planet and its five moons on July 14, 2015.

Pluto and Charon were observed for an entire rotation of each body; a “day” on Pluto and Charon is 6.4 Earth days. The first of the images was taken when New Horizons was about 3 billion miles from Earth, but just 126 million miles (203 million kilometers) from Pluto—about 30% farther than Earth’s distance from the Sun. The last frame came 6½ days later, with New Horizons more than 5 million miles (8 million kilometers) closer.

The wobble easily visible in Pluto’s motion, as Charon orbits, is due to the gravity of Charon, about one-eighth as massive as Pluto and about the size of Texas.

Faint stars can be seen in background of these images. Each frame had an exposure time of one-tenth of a second, too short to see Pluto’s smaller, much fainter moons. New Horizons is still too far from Pluto and its moons to resolve surface features.


Animation above: This close up look at Pluto and Charon. Image Credit: NASA/APL/Southwest Research Institute.

The Pluto-Charon Dance: This close up look at Pluto and Charon, taken as part of the mission’s latest optical navigation (“OpNav”) campaign from Jan. 25-31, 2015, comes from the Long Range Reconnaissance Imager (LORRI) on NASA;s New Horizons spacecraft.

The time-lapse frames in this movie were magnified four times to make it easier to see Pluto and Charon orbit around their barycenter, a mutual point above Pluto’s surface where Pluto and Charon’s gravity cancels out – this is why Pluto appears to “wobble” in space. Charon orbits approximately 11,200 miles (about 18,000 kilometers) above Pluto’s surface.

Each frame had an exposure time of one-tenth of a second, too short to see Pluto’s smaller, much fainter moons.

"These images allow the New Horizons navigators to refine the positions of Pluto and Charon, and they have the additional benefit of allowing the mission scientists to study the variations in brightness of Pluto and Charon as they rotate, providing a preview of what to expect during the close encounter in July," says Alan Stern, the New Horizons principal investigator from the Southwest Research Institute in Boulder, Colorado.

NASA’s New Horizons spacecraft. Image Credit: NASA

The Johns Hopkins University Applied Physics Laboratory manages the New Horizons mission for NASA's Science Mission Directorate in Washington. Alan Stern, of the Southwest Research Institute (SwRI), headquartered in San Antonio, is the principal investigator and leads the mission. SwRI leads the science team, payload operations, and encounter science planning. New Horizons is part of the New Frontiers Program managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. APL designed, built and operates the spacecraft.

For more information about New Horizons mission, visit: http://www.nasa.gov/mission_pages/newhorizons/main/

Animations & Image (mentioned), Text, Credits: NASA.

Cheers, Orbiter.ch

A New Way to View Titan: 'Despeckle' It












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

February 12, 2015

-- Radar images of Titan have always had a grainy appearance due to electronic noise.

-- A new tool suppresses the noise, resulting in clearer views than ever before.

During 10 years of discovery, NASA's Cassini spacecraft has pulled back the smoggy veil that obscures the surface of Titan, Saturn's largest moon. Cassini's radar instrument has mapped almost half of the giant moon's surface; revealed vast, desert-like expanses of sand dunes; and plumbed the depths of expansive hydrocarbon seas. What could make that scientific bounty even more amazing? Well, what if the radar images could look even better?


Images above: Presented here are side-by-side comparisons of a traditional Cassini Synthetic Aperture Radar (SAR) view and one made using a new technique for handling electronic noise that results in clearer views of Titan's surface. Image Credit: NASA/JPL-Caltech/ASI.

Thanks to a recently developed technique for handling noise in Cassini's radar images, these views now have a whole new look. The technique, referred to by its developers as "despeckling," produces images of Titan's surface that are much clearer and easier to look at than the views to which scientists and the public have grown accustomed.

Typically, Cassini's radar images have a characteristic grainy appearance. This "speckle noise" can make it difficult for scientists to interpret small-scale features or identify changes in images of the same area taken at different times. Despeckling uses an algorithm to modify the noise, resulting in clearer views that can be easier for researchers to interpret.

Antoine Lucas got the idea to apply this new technique while working with members of Cassini's radar team when he was a postdoctoral researcher at the California Institute of Technology in Pasadena.


Image above: This Cassini Synthetic Aperture Radar (SAR) image is presented as a perspective view and shows a landscape near the eastern shoreline of Kraken Mare, a hydrocarbon sea in Titan's north polar region. Image Credit: NASA/JPL-Caltech/ASI.

"Noise in the images gave me headaches," said Lucas, who now works at the astrophysics division of France's nuclear center (CEA). Knowing that mathematical models for handling the noise might be helpful, Lucas searched through research published by that community, which is somewhat disconnected from people working directly with scientific data. He found that a team near Paris was working on a “de-noising” algorithm, and he began working with them to adapt their model to the Cassini radar data. The collaboration resulted in some new and innovative analysis techniques.

"My headaches were gone, and more importantly, we were able to go further in our understanding of Titan’s surface using the new technique," Lucas said.

As helpful as the tool has been, for now, it is being used selectively.


Images above: This montage of Cassini Synthetic Aperture Radar (SAR) images of the surface of Titan shows four examples of how a newly developed technique for handling noise results in clearer, easier to interpret views. Image Credit: NASA/JPL-Caltech/ASI.

"This is an amazing technique, and Antoine has done a great job of showing that we can trust it not to put features into the images that aren’t really there," said Randy Kirk, a Cassini radar team member from the U.S. Geologic Survey in Flagstaff, Arizona. Kirk said the radar team is going to have to prioritize which images are the most important to applying the technique. "It takes a lot of computation, and at the moment quite a bit of 'fine-tuning' to get the best results with each new image, so for now we'll likely be despeckling only the most important -- or most puzzling -- images," Kirk said.

Despeckling Cassini's radar images has a variety of scientific benefits. Lucas and colleagues have shown that they can produce 3-D maps, called digital elevation maps, of Titan's surface with greatly improved quality. With clearer views of river channels, lake shorelines and windswept dunes, researchers are also able to perform more precise analyses of processes shaping Titan's surface. And Lucas suspects that the speckle noise itself, when analyzed separately, may hold information about properties of the surface and subsurface.


Images above: Presented here are side-by-side comparisons of a traditional Cassini Synthetic Aperture Radar (SAR) view, at left, and one made using a new technique for handling electronic noise that results in clearer views of Titan's surface, at right. Image Credit: NASA/JPL-Caltech/ASI.

"This new technique provides a fresh look at the data, which helps us better understand the original images," said Stephen Wall, deputy team lead of Cassini's radar team, which is based at NASA's Jet Propulsion Laboratory in Pasadena, California. "With this innovative new tool, we will look for details that help us to distinguish among the different processes that shape Titan’s surface," he said.

Details about the new technique were published recently in the Journal of Geophysical Research: Planets.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the US and several European countries.

More information about Cassini: 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.

Greetings, Orbiter.ch

mercredi 11 février 2015

NOAA’s New Deep Space Solar Monitoring Satellite Launched

















SpaceX - Falcon 9 / DSCOVR launch patch.

February 11, 2015

Falcon 9 rocket carrying DSCOVR ready for launch

A new mission to monitor solar activity is now making its way to an orbit one million miles from Earth. The Deep Space Climate Observatory (DSCOVR) launched on a SpaceX Falcon 9 rocket at 6:03 p.m. EST Wednesday from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida.

video
DSCOVR Launches Aboard SpaceX Falcon 9

DSCOVR, a partnership among the National Oceanic and Atmospheric Administration (NOAA), NASA and the U.S. Air Force, will provide NOAA space weather forecasters more reliable measurements of solar wind conditions, improving their ability to monitor potentially harmful solar activity.

NASA received funding from NOAA to refurbish the DSCOVR spacecraft and its solar wind instruments for this mission. The work was completed at NASA’s Goddard Space Flight Center in Greenbelt, MD, where a team developed the command and control portion of the spacecraft’s ground segment, and manages the launch and activation of the satellite.

Falcon 9 rocket launched by SpaceX and carrying DSCOVR

Following successful activation of the satellite and check-out approximately 150 days after launch, NASA will hand over operations of DSCOVR to NOAA.

“DSCOVR is the latest example of how NASA and NOAA work together to leverage the vantage point of space to both understand the science of space weather and provide direct practical benefits to us here on Earth,” said John Grunsfeld, associate administrator of NASA’s Science Mission Directorate in Washington.

With DSCOVR in its distant orbit, it will become the nation’s first operational satellite in deep space, orbiting between Earth and the sun at a location called the first Lagrange point, or L1. DSCOVR will join at this orbit NASA’s Advanced Composition Explorer (ACE) research satellite, and replace the 17-year-old satellite as America’s primary warning system for solar magnetic storms. ACE will continue its important role in space weather research.

NOAA management of DSCOVR includes spacecraft operation and distribution of the mission’s space weather data. These data, coupled with a new forecast model scheduled to come online later this year, will enable NOAA forecasters to predict geomagnetic storm magnitude on a regional basis.

Deep Space Climate Observatory (DSCOVR) spacecraft

Geomagnetic storms occur when plasma and magnetic fields streaming from the sun impact Earth’s magnetic field. Large magnetic eruptions from the sun have the potential to bring major disruptions to power grids, aviation, telecommunications, and GPS systems.

In addition to the mission’s primary space weather-monitoring instruments, DSCOVR carries two NASA Earth-observing instruments that will gather a range of measurements from the ozone and aerosols in the atmosphere, to changes in Earth's radiation budget. A NASA solar-science instrument, the Electron Spectrometer, will measure electrons in the solar wind.

The National Institute of Standards and Technology Advanced Radiometer (NISTAR) measures the reflected and emitted energy from the entire sunlit face of Earth. This measurement is intended to improve understanding of the effects of changes in Earth's radiation budget caused by human activities and natural phenomena.

Images of the entire sunlit face of Earth, with ten filter settings in the ultraviolet and visible spectral ranges, are provided by the Earth Polychromatic Imaging Camera (EPIC) instrument on DSCOVR.  EPIC's observations will be used to measure ozone and aerosol amounts, cloud height, vegetation properties and ultraviolet reflectivity of Earth.

Data from EPIC will be used to create true-color images of the full sun-facing side of Earth that will be publicly available approximately 24 hours after they are taken. At least six images will be produced each day and posted to the NASA website. The first images will be posted approximately six months after launch.

For more information on the DSCOVR mission, visit: http://www.nesdis.noaa.gov/DSCOVR/

For more information about Dragon resupply spacecraft, visit: http://www.spacex.com/

Images, Video, Text, Credits: NASA/NOAA/SpaceX.

Greetings, Orbiter.ch

Giant Filament Seen on the Sun












NASA - Solar Dynamics Observatory (SDO) patch.

February 11, 2015


A dark, snaking line across the lower half of the sun in this Feb. 10, 2015 image from NASA's Solar Dynamics Observatory (SDO) shows a filament of solar material hovering above the sun's surface. SDO shows colder material as dark and hotter material as light, so the line is, in fact, an enormous swatch of colder material hovering in the sun's atmosphere, the corona. Stretched out, that line – or solar filament as scientists call it – would be more than 533,000 miles long. That is longer than 67 Earths lined up in a row. Filaments can float sedately for days before disappearing. Sometimes they also erupt out into space, releasing solar material in a shower that either rains back down or escapes out into space, becoming a moving cloud known as a coronal mass ejection, or CME. SDO captured images of the filament in numerous wavelengths, each of which helps highlight material of different temperatures on the sun. By looking at such features in different wavelengths and temperatures, scientists learn more about what causes these structures, as well as what catalyzes their occasional eruptions.

Launched on Feb. 11, 2010 aboard a ULA Atlas V rocket from Cape Canaveral Air Force Station, Fla., NASA's Solar Dynamics Observatory is designed to study the causes of solar variability and its impacts on Earth. The spacecraft's long-term measurements give solar scientists in-depth information to help characterize the interior of the sun, the sun's magnetic field, the hot plasma of the solar corona, and the density of radiation that creates the ionosphere of the planets. The information is used to create better forecasts of space weather needed to protect aircraft, satellites and astronauts living and working in space.

video
SDO: Year 5

Video above:

February 11, 2015 marks five years in space for NASA's Solar Dynamics Observatory, which provides incredibly detailed images of the whole sun 24 hours a day. Capturing an image more than once per second, SDO has provided an unprecedentedly clear picture of how massive explosions on the sun grow and erupt ever since its launch on Feb. 11, 2010. The imagery is also captivating, allowing one to watch the constant ballet of solar material through the sun's atmosphere, the corona.

In honor of SDO's fifth anniversary, NASA has released a video showcasing highlights from the last five years of sun watching. Watch the movie to see giant clouds of solar material hurled out into space, the dance of giant loops hovering in the corona, and huge sunspots growing and shrinking on the sun's surface.

The imagery is an example of the kind of data that SDO provides to scientists. By watching the sun in different wavelengths – and therefore different temperatures – scientists can watch how material courses through the corona, which holds clues to what causes eruptions on the sun, what heats the sun's atmosphere up to 1,000 times hotter than its surface, and why the sun's magnetic fields are constantly on the move.

Five years into its mission, SDO continues to send back tantalizing imagery to incite scientists' curiosity. For example, in late 2014, SDO captured imagery of the largest sun spots seen since 1995 as well as a torrent of intense solar flares. Solar flares are bursts of light, energy and X-rays. They can occur by themselves or can be accompanied by what's called a coronal mass ejection, or CME, in which a giant cloud of solar material erupts off the sun, achieves escape velocity and heads off into space. In this case, the sun produced only flares and no CMEs, which, while not unheard of, is somewhat unusual for flares of that size. Scientists are looking at that data now to see if they can determine what circumstances might have led to flares eruptions alone.

Goddard built, operates and manages the SDO spacecraft for NASA's Science Mission Directorate in Washington, D.C. SDO is the first mission of NASA's Living with a Star Program. The program's goal is to develop the scientific understanding necessary to address those aspects of the sun-Earth system that directly affect our lives and society.

For more information about Solar Dynamics Observatory (SDO), visit: http://www.nasa.gov/mission_pages/sdo/main/

Image, Video, Text, Credits: NASA/SDO.

Greetings, Orbiter.ch

ESA experimental spaceplane completes research flight









ESA - Intermediate eXperimental Vehicle patch.

11 February 2015

An experimental vehicle to develop an autonomous European reentry capability for future reusable space transportation has completed its mission. ESA’s Intermediate eXperimental Vehicle flew a flawless reentry and splashed down in the Pacific Ocean just west of the Galapagos islands.

Vega VV04 liftoff with IXV spaceplane

The IXV spaceplane lifted off at 13:40 GMT (14:40 CET, 10:40 local time) on 11 February from Europe’s Spaceport in Kourou, French Guiana atop a Vega rocket. It separated from Vega at an altitude of 340 km and continued up to 412 km. Reentering from this suborbital path, it recorded a vast amount of data from more than 300 advanced and conventional sensors.

video
Vega liftoff VV04 with IXV

As it descended, the five-metre-long, two-tonne craft manoeuvred to decelerate from hypersonic to supersonic speed. The entry speed of 7.5 km/s at an altitude of 120 km created the same conditions as those for a vehicle returning from low Earth orbit.

IXV glided through the atmosphere before parachutes deployed to slow the descent further for a safe splashdown in the Pacific Ocean.

The Mission Control Centre at the ALTEC Advanced Logistics Technology Engineering Centre in Turin, Italy, closely monitored IXV during the mission, receiving flight and instrument data from the entire ground network, including the fixed ground stations in Libreville (Gabon) and Malindi (Kenya), and the station on the Nos Aries recovery ship in the Pacific.

Vega VV04 IXV Liftoff

Balloons are now keeping IXV afloat while the recovery vessel hurries to pick it up. It will be returned to Europe for detailed analysis in ESA’s technical centre, ESTEC, in the Netherlands.

Mastering reentry will open a new chapter for ESA. Such a capability is a cornerstone for reusable launcher stages, sample return from other planets and crew return from space, as well as for future Earth observation, microgravity research, satellite servicing and disposal missions.

The initial results from the flight are expected to be released in around six weeks.

The results will feed the Programme for Reusable In-Orbit Demonstrator for Europe, or Pride, which is being studied under funding decided at ESA’s last two Ministerial Councils. The reusable Pride spaceplane would be launched on Europe’s Vega light rocket, orbit and land automatically on a runway.

IXV floating and waiting for recovery

“IXV has opened a new chapter for ESA in terms of reentry capabilities and reusability,” explains Jean-Jacques Dordain, ESA Director General.

“ESA and its Member States, together with European space industry, are now ready to take up new challenges in several fields of space transportation, in future launchers, robotic exploration or human spaceflight.”

“This mission will teach us a lot about the technologies we need to apply in new launch systems, in particular when we think about reusable systems,” notes Gaele Winters, ESA Director of Launchers.

“This was a short mission with big impact,” notes Giorgio Tumino, IXV project manager.

“The cutting-edge technology we validated today, and the data gathered from the sensors aboard IXV, will open numerous opportunities for Europe to develop ambitious plans in space transportation for a multitude of applications.”

ESA will provide footage of the recovery when it is available from the ship in the Pacific Ocean.

Still pictures will be made available at: http://www.esa.int/spaceinimages/Missions/IXV

Milestone mission for Vega

The launch also allowed the new Vega rocket to show its impressive capabilities, and to confirm its flexibility for a wide range of missions.

Since its introduction in 2012, the launcher has reduced operational costs and delivered its first commercial customers into orbit, as well as demonstrating numerous capabilities such as dual payloads and different orbits.

Today’s mission was the first Vega payload to require an equatorial launch trajectory, instead of travelling northwards as on previous missions. It was also the heaviest payload so far.

For more information about ESA’s Intermediate eXperimental Vehicle, visit: http://www.esa.int/Our_Activities/Launchers/IXV

Images, Video, Text, Credits: ESA/S. Corvaja.

Best regards, Orbiter.ch

Dragon Splashes Down Ending SpaceX Mission












SpaceX - Falcon 9 / Dragon CRS-5 mission patch.

February 11, 2015

 Dragon is slowed by three main parachutes prior to splashdown into the Pacific Ocean

SpaceX’s Dragon cargo spacecraft splashed down in the Pacific Ocean at about 7:44 p.m. EST 259 miles southwest of Long Beach, California, marking the end of the company’s fifth contracted cargo resupply mission to the International Space Station.

The spacecraft is returning about 3,700 pounds of NASA cargo and science samples from the International Space Station. A SpaceX vessel will take the Dragon spacecraft to Long Beach, where some cargo will be removed and returned to NASA. Dragon will be prepared for a return journey to SpaceX’s test facility in McGregor, Texas, for processing.

Dragon recovered aboard SpaceX ship

The mission was the fifth of 12 cargo resupply trips SpaceX will make to the space station through 2016 under NASA’s Commercial Resupply Services contract.

For more information about Dragon resupply spacecraft, visit: http://www.spacex.com/

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

Images, Text, Credits: NASA/SpaceX.

Greetings, Orbiter.ch

mardi 10 février 2015

Why Comets Are Like Deep Fried Ice Cream












ESA - Rosetta Mission patch.

February 10, 2015

--Studying comet composition helps explain how early Earth may have received water and organics.

--New research used "Himalaya," an icebox-like instrument.

Astronomers tinkering with ice and organics in the lab may have discovered why comets are encased in a hard, outer crust.

Using an icebox-like instrument nicknamed Himalaya, the researchers show that fluffy ice on the surface of a comet would crystalize and harden as the comet heads toward the sun and warms up. As the water-ice crystals form, becoming denser and more ordered, other molecules containing carbon would be expelled to the comet's surface. The result is a crunchy comet crust sprinkled with organic dust.


Image above: Comet 67P/Churyumov-Gerasimenko is seen here in an image captured by the Rosetta spacecraft. The mission's Philae lander hit the surface with a big bounce, demonstrating the comet's surface is hard. Image Credit: ESA/Rosetta/NAVCAM.

"A comet is like deep fried ice cream," said Murthy Gudipati of NASA's Jet Propulsion Laboratory in Pasadena, California, corresponding author of a recent study appearing in The Journal of Physical Chemistry. "The crust is made of crystalline ice, while the interior is colder and more porous. The organics are like a final layer of chocolate on top."

The lead author of the study is Antti Lignell, a postdoctoral scholar at the California Institute of Technology in Pasadena, who formerly worked with Gudipati at JPL.

Researchers already knew that comets have soft interiors and seemingly hard crusts. NASA's Deep Impact and the European Space Agency's Rosetta spacecraft both inspected comets up close, finding evidence of soft, porous interiors. Last November, Rosetta's Philae probe bounced to a landing on the surface of 67P/Churyumov-Gerasimenko, confirming that comets have a hard surface. The black, soot-like coats of comets, made up of organic molecules and dust, had also been seen before by the Deep Impact mission.

But the exact composition of comet crust -- and how it forms -- remains unclear.

In the new study, researchers turned to labs on Earth to put together a model of crystallizing comet crust. The experiments began with amorphous, or porous, ice -- the proposed composition of the chilliest of comets and icy moons. In this state, water vapor molecules are flash-frozen at extremely cold temperatures of around 30 Kelvin (minus 243 degrees Celsius, or minus 405 degrees Fahrenheit), sort of like Han Solo in the Star Wars movie "The Empire Strikes Back." Disorderly states are preserved: Water molecules are haphazardly mixed with other molecules, such as the organics, and remain frozen in that state. Amorphous ice is like cotton candy, explains Gudipati: light and fluffy and filled with pockets of space.

On Earth, all ice is in the crystalline form. It's not cold enough to form amorphous ice on our planet. Even a handful of loose snow is in the crystalline form, but contains much smaller ice crystals than those in snowflakes.


Image above: Researchers at NASA's Jet Propulsion Laboratory in Pasadena, California, use a cryostat instrument, nicknamed "Himalaya," to study the icy conditions under which comets form. Image Credit: NASA/JPL-Caltech.

Gudipati and Lignell used their Himalaya cryostat instrument to slowly warm their amorphous ice mixtures from 30 Kelvin to 150 Kelvin (minus 123 degrees Celsius, or minus 190 degrees Fahrenheit), mimicking conditions a comet would experience as it journeys toward the sun. The ice had been infused with a type of organics, called polycyclic aromatic hydrocarbons, or PAHs, which are seen everywhere in deep space.

The results came as a surprise

"The PAHs stuck together and were expelled from the ice host as it crystallized. This may be the first observation of molecules clustering together due to a phase transition of ice, and this certainly has many important consequences for the chemistry and physics of ice," said Lignell.

With PAHs kicked out of the ice mixtures, the water molecules had room to link up and form the more tightly packed structures of crystalline ice.

"What we saw in the lab -- a crystalline comet crust with organics on top -- matches what has been suggested from observations in space," said Gudipati. Deep fried ice cream is really the perfect analogy, because the interior of the comets should still be very cold and contain the more porous, amorphous ice."

The composition of comets is important to understanding how they might have delivered water and organics to our nascent, bubbling-hot Earth. New results from the Rosetta mission show that asteroids may have been the primary carriers of life's ingredients; however, the debate is ongoing and comets may have played a role. For Gudipati, comets are capsules containing clues not only to our planet's history but to the birth of our entire solar system.

He said, "It's beautiful to think about how far we have come in our understanding of comets. Future missions designed to bring cold samples of comets back to Earth could allow us to fully unravel their secrets."

Rosetta is a European Space Agency mission with contributions from its member states and NASA. JPL, a division of the California Institute of Technology in Pasadena, manages the U.S. contribution of the Rosetta mission for NASA's Science Mission Directorate in Washington. Caltech manages JPL for NASA.

Technical journal article: http://pubs.acs.org/doi/abs/10.1021/jp509513s

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

Images (mentioned), Text, Credits: NASA/JPL/Whitney Clavin.

Greetings, Orbiter.ch

Mars Rover Nearing Marathon Achievement











NASA - Mars Exploration Rover "Opportunity" (MER-B) patch.

February 10, 2015

-- Opportunity rover approaches marathon milestone of 42.195 kilometers

-- Rover's science destination is "Marathon Valley"

NASA's Mars Exploration Rover Opportunity is nearing a location on Mars at which its driving distance will surpass the length of a marathon race.


Image above: In February 2015, NASA's Mars Exploration Rover Opportunity is approaching a cumulative driving distance on Mars equal to the length of a marathon race. This map shows the rover's position relative to where it could surpass that distance. Image Credit: NASA/JPL-Caltech/Univ. of Arizona.

A drive on Feb. 8, 2015, put the rover within 220 yards (200 meters) of this marathon accomplishment. An Olympic marathon is 26.219 miles (42.195 kilometers).

Opportunity is headed for a portion of the western rim of Endeavour Crater where observations by NASA's Mars Reconnaissance Orbiter have detected multiple types of clay minerals. These minerals are indicative of an ancient wet environment where water was more neutral rather than harshly acidic. More than six months ago, the rover team informally named that destination "Marathon Valley," having estimated what the odometry would total by the time Opportunity gets there.

"When Opportunity was in its prime mission 11 years ago, no one imagined this vehicle surviving a Martian winter, let alone completing a marathon on Mars," said Mars Exploration Rover Project Manager John Callas of NASA's Jet Propulsion Laboratory, Pasadena, California. "Now, that achievement is within reach as Opportunity approaches a strategic science destination. What's most important about the longevity and driving distance the mission keeps extending are not numerical thresholds, but the wealth of scientific information returned about Mars, made possible by these feats."

Before driving Opportunity into Marathon Valley, the team plans to use the rover for observations of an impact crater called "Spirit of Saint Louis Crater," at the entrance to the valley.

The team is operating Opportunity in a mode that avoids use of the rover's flash memory. In this mode, data gathered during each Martian day are stored in volatile memory and transmitted to an orbiter before the rover's overnight, energy-conserving "sleep."  NASA orbiters Mars Odyssey and Mars Reconnaissance Orbiter relay the rover data to Earth.

Opportunity engineers plan in coming weeks to upload a software revision they have developed to enable resuming use of non-volatile flash memory. It is designed to restore Opportunity's capability to store data overnight or longer, for transmitting later.


Image above: Artist's view of the Mars Exploration Rover "Opportunity" (MER-B). Image Credits: NASA/JPL-Caltech.

During its original three-month prime mission, beginning after landing on Jan. 25, 2004, UST (Jan. 24, 2004, PST) Opportunity drove 0.48 mile (771.5 meters). Its twin, NASA's Mars Exploration Rover Spirit, landed three weeks earlier and covered 0.39 mile (635 meters) in its three-month prime mission. Both Spirit and Opportunity have returned compelling evidence about wet environments on ancient Mars. Spirit's mission ended in 2010. Since 2011, Opportunity has been investigating the western rim of Endeavour, a crater that is 14 miles (22 kilometers) in diameter.

The rover climbed to its highest elevation on the Endeavour rim on Jan. 6, 2015, reaching a point about 440 feet (135 meters) above the local plains. It has driven about 440 yards (400 meters) since then, mainly southward toward the entrance to Marathon Valley.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover Project for NASA's Science Mission Directorate in Washington. For more information about Spirit and Opportunity, visit: http://www.nasa.gov/rovers and http://marsrovers.jpl.nasa.gov

You can follow the project on Twitter and on Facebook at: http://twitter.com/MarsRovers and http://www.facebook.com/mars.rovers

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

Greetings, Orbiter.ch

Dragon Set Free for Splashdown and Recovery












SpaceX - Falcon 9 / Dragon CRS-5 Mission patch.

10 February 2015

The SpaceX Dragon cargo spacecraft was released from the International Space Station’s robotic arm at 2:10 p.m. EST. The capsule was maneuvered outside the vicinity of the space station in preparation for its return trip to Earth. The capsule is currently scheduled to splashdown in the Pacific Ocean at about 7:44 p.m., 259 miles southwest of Long Beach, California.

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SpaceX Dragon CRS-5 Departs International Space Station

Robotics controllers on the ground removed the SpaceX Dragon from the Harmony node Tuesday morning after they finished packing it full of critical research and gear Monday. Italian astronaut Samantha Cristoforetti, backed up by Flight Engineer Terry Virts, commanded the Canadarm2 to release Dragon.


Image above: Samantha Cristoforetti commanded the Canadarm2 to release the SpaceX Dragon from its grip. Image Credit: NASA TV.

Cristoforetti also worked on orbital plumbing during the day before heading to the cupola for the release. Earlier, Commander Butch Wilmore and Virts demated the jumper cables and depressurized the vestibule which is the interface between Harmony and Dragon. The NASA astronauts also had time set aside to organize tools ahead of three spacewalks to install cables the first of which is set to begin Feb. 20.

The cosmonauts continued their work conducting Russian science and stowing trash and gear inside the ISS Progress 57 (57P) resupply ship.

For more information about Dragon resupply spacecraft, visit: http://www.spacex.com/

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

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

Best regards, Orbiter.ch

ATV to bid farewell to Space Station for last time












ESA - ATV-5 Georges Lemaître Mission patch.

10 February 2015

ESA’s last Automated Transfer Vehicle will leave the International Space Station on Saturday for its final solo voyage, setting course for a fiery demise that will mark the end of its mission and the programme.

The last of five Automated Transfer Vehicles, Georges Lemaître has had an event-filled mission that has displayed the spacecraft’s versatility. ATV-5 was launched only nine months after predecessor Albert Einstein finished its mission to supply and reboost the orbital complex.

ATV-5

ATV-5 is the heaviest spacecraft ever lofted by an Ariane rocket, and delivered 6617 kg of supplies and experiments to the Station.

Before docking, it flew under the Station to demonstrate new laser and infrared imaging technology that will help future spacecraft to rendezvous with uncontrolled objects.

ESA astronaut Alexander Gerst and Russian cosmonaut Alexander Skvortsov oversaw the automated docking on 12 August and quickly began unloading the many items in its cargo hold. Over the last six months, the crew have unpacked the cargo and in turn have loaded ATV-5 with rubbish.

ATV-5 liftoff last year

Meanwhile, mission controllers in Toulouse, France, have commanded oxygen, air, fuel and water to pump into the Station’s tanks.

In October Georges Lemaître was the first ATV to push the Station out of the way of space debris using a special manoeuvre requiring less preparation than usual. It repeated the trick just two weeks later.

Monitoring ATV-5 docking from Space Station

Last month ATV-5 took the Station into a lower orbit, slowing their orbital speed after the outpost had turned around. This rare manoeuvre had not been performed since 2008, by the first ATV, and will allow other supply spacecraft to bring heavier cargo to the Station.

Reentry redux

ATV-5 was set to enter the atmosphere at the end of February in a new, shallow dive that would have allowed NASA and ESA teams to observe the spacecraft closely and learn from its reentry.

However, one of the four power chains failed last week, leading it to switch automatically over to its ‘failsafe’ system. ATV is designed to continue its normal mission with one failure, and can still be controlled safely even with two.

ATV-4 reentry

The increased risk of a second failure in the 13 days of free flight before the 27 February reentry, and the impossibility of shortening this phase because of heavy Station traffic and other ATV operational constraints, has led ESA to cancel the shallow reentry.

As a result, George Lemaître will follow the standard reentry profile around 30 hours after undocking, just like its predecessors.

Two experiments are ready in ATV’s cargo hold: both will monitor the temperature and record other information as it reenters in a  controlled dive, transmitting recorded data to researchers.

ATV Control Centre

“The ATV team has worked tirelessly for five missions in a row,” says ATV-5 mission manager Massimo Cislaghi.

“While teams are sincerely disappointed not to conduct the planned shallow reentry, the revised plan doesn’t alter the programme’s overall success.

“The ATVs are large and complex spacecraft and they have achieved every goal, demonstrating Europe’s technical expertise and the skill of teams at ESA, France’s CNES space agency and the many industrial partners.”

While this is the last of the ATV flights, the knowhow and technology that have gone into the series will soon fly again as early as 2017 to power NASA’s Orion spacecraft with the European Service Module, paving the way for the next era in  space exploration.

Follow the ATV blog for live updates and behind-the-scenes information: http://blogs.esa.int/atv

Related link:

ATV Control Centre: http://www.esa.int/Our_Activities/Human_Spaceflight/ATV/ATV_Control_Centre

For more information about the Automated Transfer Vehicle (ATV), visit: http://www.esa.int/Our_Activities/Human_Spaceflight/ATV

Images, Text, Credits: ESA/J. Harrod/S. Corvaja/NASA/Roscosmos/O. Artemiev.

Greetings, Orbiter.ch

Hubble Sees A Smiling Lens












NASA - Hubble Space Telescope patch.

10 February 2015


In the center of this image, taken with the NASA/ESA Hubble Space Telescope, is the galaxy cluster SDSS J1038+4849 — and it seems to be smiling.

You can make out its two orange eyes and white button nose. In the case of this “happy face”, the two eyes are very bright galaxies and the misleading smile lines are actually arcs caused by an effect known as strong gravitational lensing.

Galaxy clusters are the most massive structures in the Universe and exert such a powerful gravitational pull that they warp the spacetime around them and act as cosmic lenses which can magnify, distort and bend the light behind them. This phenomenon, crucial to many of Hubble’s discoveries, can be explained by Einstein’s theory of general relativity.

In this special case of gravitational lensing, a ring — known as an Einstein Ring — is produced from this bending of light, a consequence of the exact and symmetrical alignment of the source, lens and observer and resulting in the ring-like structure we see here.

Hubble has provided astronomers with the tools to probe these massive galaxies and model their lensing effects, allowing us to peer further into the early Universe than ever before. This object was studied by Hubble’s Wide Field and Planetary Camera 2 (WFPC2) and Wide Field Camera 3 (WFC3) as part of a survey of strong lenses.

video
 Hubble space telescope orbiting the Earth

A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Judy Schmidt.

More information and image products: http://www.spacetelescope.org/images/potw1506a/

For more information and multi-media contents, visit: http://www.spacetelescope.org/ and http://hubblesite.org/

Image, Video, Text, Credits: NASA/ESA/Caption: ESA.

Cheers, Orbiter.ch

lundi 9 février 2015

Satellite Eyes New England Winter Storm Breaking Records












NOAA / NASA - GOES Program logo.

February 9, 2015


Another large snowstorm affecting New England was dropping more snow on the region and breaking records on February 9, as NOAA's GOES-East satellite captured an image of the clouds associated with the storm system.

On Feb. 9, NOAA's National Weather Service in Boston, Massachusetts noted that "The 30-day snowfall total at Boston ending 7 a.m. this morning is 61.6 inches. This exceeds the previous maximum 30 day snowfall total on record at Boston, which was 58.8 inches ending Feb 7 1978."

The GOES-East image was created by NASA/NOAA's GOES Project at NASA's Goddard Space Flight Center in Greenbelt, Maryland. It showed a blanket of clouds over the U.S. northeast that stretched down to the Mid-Atlantic where there was no snow on the ground in Washington, D.C.

NOAA's National Weather Service Weather Prediction Center provided a look at the extent of the storm system and noted "Heavy snow will impact portions of New York State and New England as the new week begins. Freezing rain will spread from western Pennsylvania to Long Island, with rain for the mid-Atlantic states." The low pressure area bringing the snow to the northeast was located in central Pennsylvania. A cold front extended southward from the low across the Tennessee Valley while a stationary boundary extended eastward from the low across the central mid-Atlantic.

 NOAA's GOES-East weather satellite

To create the image, NASA/NOAA's GOES Project takes the cloud data from NOAA's GOES-East satellite and overlays it on a true-color image of land and ocean created by data from the Moderate Resolution Imaging Spectroradiometer, or MODIS, instrument that flies aboard NASA's Aqua and Terra satellites. Together, those data created the entire picture of the storm.

NOAA's GOES satellites provide the kind of continuous monitoring necessary for intensive data analysis. Geostationary describes an orbit in which a satellite is always in the same position with respect to the rotating Earth. This allows GOES to hover continuously over one position on Earth's surface, appearing stationary. As a result, GOES provide a constant vigil for the atmospheric triggers for severe weather conditions such as tornadoes, flash floods, hail storms and hurricanes.

For updated information about the storm system, visit NOAA's NWS website: http://www.weather.gov

For more information about GOES satellites, visit: http://www.goes.noaa.gov/ or http://goes.gsfc.nasa.gov/

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

Greetings, Orbiter.ch

NASA Spacecraft Completes 40,000 Mars Orbits












NASA - Mars Reconnaissance Orbiter (MRO) patch.

February 9, 2015

-- NASA's Mars Reconnaissance Orbiter, at Mars since 2006, has now orbited the Red Planet more than 40,000 times

-- The continuing mission studies the whole planet and has shown that Mars is diverse and dynamic

NASA's Mars Reconnaissance Orbiter passed a mission milestone of 40,000 orbits on Feb. 7, 2015, in its ninth year of returning information about the atmosphere, surface and subsurface of Mars, from equatorial to polar latitudes.


Image above: This view of Martian surface features shaped by effects of winds was captured by the HiRISE camera on NASA's Mars Reconnaissance Orbiter on Jan. 4, 2015. Image Credit: NASA/JPL-Caltech/Univ. of Arizona.

The mission's potent science instruments and extended lifespan have revealed that Mars is a world more dynamic and diverse than was previously realized. Now in its fourth mission extension after a two-year prime mission, the orbiter is investigating seasonal and longer-term changes, including some warm-season flows that are the strongest evidence so far for liquid water on Mars today.

The orbiter has returned 247 terabits of data, which is more than the combined total from every other mission that has ever departed Earth to visit another planet.

It circles Mars at an altitude of about 186 miles (300 kilometers), on a near-polar pattern, about 12 times a day. In its 40,000 orbits, the spacecraft has flown nearly twice as far as the 310 million miles (500 million kilometers) it flew during its 2006 journey from Earth to Mars.

The mission has illuminated three very different periods of Mars history. Its observations of the heavily cratered terrains of Mars, the oldest on the planet, show that different types of ancient watery environments formed water-related minerals. Some of these environments would have been more favorable for life than others.

In more recent times, water appears to have cycled as a gas between polar ice deposits and lower-latitude deposits of ice and snow. Extensive layering in ice or rock probably took at least hundreds of thousands, and possibly millions of years to form. Like ice ages on Earth, the layering is linked to cyclic changes in the tilt of the planet's rotation axis and the changing intensity of sunlight near the poles.

Mars' present climate is also dynamic, with volatile carbon dioxide and, just possibly, summertime liquid water modifying gullies and forming new streaks. With observations of new craters, avalanches and dust storms, the orbiter has shown a partially frozen world, but not frozen in time, as change continues today.

Mars Reconnaissance Orbiter (MRO) spacecraft. Image Credit: NASA/JPL-Caltech

In addition to accomplishing its own science achievements, the Mars Reconnaissance Orbiter mission provides communication relay for missions on the surface of Mars and evaluates potential landing site candidates for surface missions.

Two other active NASA spacecraft are currently orbiting Mars -- Mars Odyssey since 2001, and MAVEN (Mars Atmosphere and Volatile Evolution) since last year. Two NASA rovers -- Opportunity and Curiosity -- are active on the surface. These robotic missions and others in development are paving the way for human-crew Mars missions in the 2030s and beyond as part of NASA's Journey to Mars strategy.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the orbiter and collaborates with JPL to operate it. For more information about the Mars Reconnaissance Orbiter, visit: http://www.nasa.gov/mro and http://mars.jpl.nasa.gov/mro/

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

Best regards, Orbiter.ch

Space Station Crew Prepares for Dragon Release After Hatches Closed










ISS - Expedition 42 Mission patch.

9 February 2015

The Expedition 42 crew closed the hatches to the Dragon commercial cargo craft today after loading it with critical gear and research. Dragon will be unberthed from the Harmony module then released from the grips of the Canadarm2 Tuesday afternoon. It will splashdown off the Pacific coast of Baja California for recovery by SpaceX engineers a couple of hours before sunset.

Read more about NASA TV coverage of the release of SpaceX Dragon: http://www.nasa.gov/press/2015/february/nasa-tv-coverage-set-for-us-cargo-ship-s-departure-from-space-station


Image above: Expedition 42 Commander and NASA Astronaut Barry Wilmore and European Space Agency Astronaut Samantha Cristoforetti used the Canadarm2 robotic arm to grapple the SpaceX Dragon (CRS-5) ship on Jan. 12 2015. Photo Credit: NASA.

Meanwhile, a trio of cosmonauts worked in the Russian segment of the International Space Station on their set of science investigations. They studied ways to locate punctures caused my micro-meteoroids on the Russian side of the station; they looked at the behavior of charged macroparticles inside a magnetic trap; they also explored crew training methods using interactive 3D manuals, or virtual manuals.

Another resupply spacecraft is counting down to its undocking from the space station this weekend. Europe’s Automated Transfer Vehicle-5 (ATV-5) is set to undock from the Zvezda service module Saturday for a fiery deorbit over the Pacific about two weeks later. Italian astronaut Samantha Cristoforetti installed internal cameras inside the ATV-5 that will record its breakup during the reentry. Engineers will use this data to understand the mechanics of a deorbiting spacecraft.

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

Image (mentioned), Text, Credit: NASA.

Cheers, Orbiter.ch

Stellar Partnership Doomed to End in Catastrophe












ESO - European Southern Observatory logo.

9 February 2015

First pair of merging stars destined to become supernova found

Artist’s impression of two white dwarf stars destined to merge and create a Type Ia supernova

Astronomers using ESO facilities in combination with telescopes in the Canary Islands have identified two surprisingly massive stars at the heart of the planetary nebula Henize 2-428. As they orbit each other the two stars are expected to slowly get closer and closer, and when they merge, about 700 million years from now, they will contain enough material to ignite a vast supernova explosion. The results will appear online in the journal Nature on 9 February 2015.

Image of the planetary nebula Henize 2-428 from the Very Large Telescope

The team of astronomers, led by Miguel Santander-García (Observatorio Astronómico Nacional, Alcalá de Henares, Spain; Instituto de Ciencia de Materiales de Madrid (CSIC), Madrid, Spain), has discovered a close pair of white dwarf stars — tiny, extremely dense stellar remnants — that have a total mass of about 1.8 times that of the Sun. This is the most massive such pair yet found [1] and when these two stars merge in the future they will create a runaway thermonuclear explosion leading to a Type Ia supernova [2].

The planetary nebula Henize 2-428 in the constellation of Aquila

The team who found this massive pair actually set out to try to solve a different problem. They wanted to find out how some stars produce such strangely shaped and asymmetric nebulae late in their lives. One of the objects they studied was the unusual planetary nebula [3] known as Henize 2-428.

“When we looked at this object’s central star with ESO’s Very Large Telescope, we found not just one but a pair of stars at the heart of this strangely lopsided glowing cloud,” says coauthor Henri Boffin from ESO.

Wide-field view of the sky around the planetary nebula Henize 2-428

This supports the theory that double central stars may explain the odd shapes of some of these nebulae, but an even more interesting result was to come.

"Further observations made with telescopes in the Canary Islands allowed us to determine the orbit of the two stars and deduce both the masses of the two stars and their separation. This was when the biggest surprise was revealed,"  reports Romano Corradi, another of the study's authors and researcher at the Instituto de Astrofísica de Canarias (Tenerife, IAC).

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Artist’s impression of two white dwarf stars merging and creating a Type Ia supernova

They found that each of the stars has a mass slightly less than that of the Sun and that they orbit each other every four hours. They are sufficiently close to one another that, according to the Einstein’s theory of general relativity, they will grow closer and closer, spiralling in due to the emission of gravitational waves, before eventually merging into a single star within the next 700 million years.

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Zooming in on the unusual planetary nebula Henize 2-428

The resulting star will be so massive that nothing can then prevent it from collapsing in on itself and subsequently exploding as a supernova. "Until now, the formation of supernovae Type Ia by the merging of two white dwarfs was purely theoretical," explains David Jones, coauthor of the article and ESO Fellow at the time the data were obtained. “The pair of stars in Henize 2-428 is the real thing!”

"It's an extremely enigmatic system," concludes Santander-García. "It will have important repercussions for the study of supernovae Type Ia, which are widely used to measure astronomical distances and were key to the discovery that the expansion of the Universe is accelerating due to dark energy".

Notes:

[1] The Chandrasekhar limit is the greatest mass that a white dwarf star can have and support itself against gravitational collapse. It has a value of about 1.4 times the mass of the Sun.

[2] Type Ia supernovae occur when a white dwarf star acquires extra mass — either by accretion from a stellar companion or by merging with another white dwarf. Once the mass exceeds the Chandrasekhar limit the star loses its ability to support itself and starts to contract. This increases the temperature and a runaway nuclear reaction occurs and blows the star to pieces.

[3] Planetary nebulae have nothing to do with planets. The name arose in the eighteenth century as some of these objects resembled the discs of the distant planets when seen through small telescopes.

More information:

This research was presented in a paper entitled “The double-degenerate, super-Chandrasekhar nucleus of the planetary nebula Henize 2-428” by M. Santander-García et al., to appear online in the journal Nature on 9 February 2015.

The team is composed of M. Santander-García (Observatorio Astronómico Nacional, Alcalá de Henares, Spain; Instituto de Ciencia de Materiales de Madrid (CSIC), Madrid, Spain), P. Rodríguez-Gil (Instituto de Astrofísica de Canarias, La Laguna, Tenerife, Spain [IAC]; Universidad de La Laguna, Tenerife, Spain), R. L. M. Corradi (IAC; Universidad de La Laguna), D. Jones (IAC; Universidad de La Laguna), B. Miszalski (South African Astronomical Observatory, Observatory, South Africa [SAAO]), H. M. J. Boffin (ESO, Santiago, Chile), M. M. Rubio-Díez (Centro de Astrobiología, CSIC-INTA, Torrejón de Ardoz, Spain) and M. M. Kotze (SAAO).

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:

Research paper in Nature: http://www.eso.org/public/archives/releases/sciencepapers/eso1505/eso1505a.pdf

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

For more information about European Southern Observatory (ESO), visit: http://www.eso.org/public/

Images, Text, Credits: ESO/L. Calçada/IAU and Sky & Telescope/Digitized Sky Survey 2/Videos: ESO/L. Calçada/Digitized Sky Survey 2/N. Risinger (skysurvey.org). Music: movetwo.

Best regards, Orbiter.ch