vendredi 2 septembre 2016

NASA’s SDO Witnesses a Double Eclipse

NASA - Solar Dynamics Observatory patch.

Sept. 2, 2016

Early in the morning of Sept. 1, 2016, NASA’s Solar Dynamics Observatory, or SDO, caught both Earth and the moon crossing in front of the sun. SDO keeps a constant eye on the sun, but during SDO’s semiannual eclipse seasons, Earth briefly blocks SDO’s line of sight each day – a consequence of SDO’s geosynchronous orbit. On Sept. 1, Earth completely eclipsed the sun from SDO’s perspective just as the moon began its journey across the face of the sun. The end of the Earth eclipse happened just in time for SDO to catch the final stages of the lunar transit.

SDO Witnesses A Double Eclipse

Video above: Early in the morning of September, 1, 2016, NASA’s Solar Dynamics Observatory, or SDO, caught both Earth and the moon passing in front of the sun. Video Credits: NASA/SDO.

In the SDO data, you can tell Earth and the moon’s shadows apart by their edges: Earth’s is fuzzy, while the moon’s is sharp and distinct. This is because Earth’s atmosphere absorbs some of the sun’s light, creating an ill-defined edge. On the other hand, the moon has no atmosphere, producing a crisp horizon.

Image above: You can tell Earth and the moon’s shadows apart by their edges: Earth’s is fuzzy, while the moon’s is sharp and distinct. This is because Earth’s atmosphere absorbs some of the sun’s light, creating an ill-defined edge. On the other hand, the moon has no atmosphere, producing a crisp horizon. Image Credits: NASA/SDO.

This particular geometry of Earth, the moon and the sun had effects on viewing down on the ground as well: It resulted in a simultaneous eclipse visible from southern Africa. The eclipse was what's known as a ring of fire, or annular, eclipse, which is similar to a total solar eclipse, except it happens when the moon is at a point in its orbit farther from Earth than average. The increased distance causes the moon’s apparent size to be smaller, so it doesn't block the entire face of the sun. This leaves a bright, narrow ring of the solar surface visible, looking much like a ring of fire.


Eclipses and Transits:

Download additional imagery at NASA's Scientific Visualization Studio:

For more information about SDO (Solar Dynamics Observatory), visit:

Image (mentioned), Video (mentioned), Text, Credits: NASA’s Goddard Space Flight Center, by Lina Tran/Ashley Morrow.


NASA Approves 2018 Launch of Mars InSight Mission

NASA - InSight Mission logo.

September 2, 2016

NASA is moving forward with a spring 2018 launch of its InSight mission to study the deep interior of Mars, following final approval this week by the agency's Science Mission Directorate.

The Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission was originally scheduled to launch in March of this year, but NASA suspended launch preparations in December due to a vacuum leak in its prime science instrument, the Seismic Experiment for Interior Structure (SEIS).

The new launch period for the mission begins May 5, 2018, with a Mars landing scheduled for Nov. 26, 2018. The next launch opportunity is driven by orbital dynamics, so 2018 is the soonest the lander can be on its way.

"Our robotic scientific explorers such as InSight are paving the way toward an ambitious journey to send humans to the Red Planet," said Geoff Yoder, acting associate administrator for NASA's Science Mission Directorate, in Washington. "It's gratifying that we are moving forward with this important mission to help us better understand the origins of Mars and all the rocky planets, including Earth."

Image above: NASA has set a new launch opportunity, beginning May 5, 2018, for the InSight mission to Mars. InSight is the first mission dedicated to investigating the deep interior of Mars. Image credits: NASA/JPL-Caltech.

The SEIS instrument -- designed to measure ground movements as small as half the radius of a hydrogen atom -- requires a perfect vacuum seal around its three main sensors in order to withstand harsh conditions on the Red Planet. Under what's known as the mission "replan," NASA's Jet Propulsion Laboratory in Pasadena, California, will be responsible for redesigning, developing and qualifying the instrument's evacuated container and the electrical feedthroughs that failed previously. France's space agency, the Centre National d'Études Spatiales (CNES), will focus on developing and delivering the key sensors for SEIS, integration of the sensors into the container, and the final integration of the instrument onto the spacecraft.

The German Aerospace Center (DLR) is contributing the Heat Flow and Physical Properties Package (HP3) to InSight's science payload.

NASA's budget for InSight was $675 million. The instrument redesign and two-year delay add $153.8 million. The additional cost will not delay or cancel any current missions, though there may be fewer opportunities for new missions in future years, from fiscal years 2017-2020.

InSight's primary goal is to help us understand how rocky planets formed and evolved. Jim Green, director of NASA's Planetary Science Division, said, "We've concluded that a replanned InSight mission for launch in 2018 is the best approach to fulfill these long-sought, high-priority science objectives."

CNES President Jean-Yves Le Gall added, "This confirmation of the launch plan for InSight is excellent news and an unparalleled opportunity to learn more about the internal structure of the Red Planet, which is currently of major interest to the international science community."

The InSight Project is managed by JPL for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the spacecraft. InSight is part of NASA's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.

For more information about InSight mission, visit:

Image (mentioned), Text, Credits: NASA/Dwayne Brown/Laurie Cantillo/JPL/Guy Webster.


Jupiter’s North Pole Unlike Anything Encountered in Solar System

NASA - JUNO Mission logo.

Sept. 2, 2016

Image above: This illustration depicts NASA's Juno spacecraft successfully entering Jupiter's orbit. Image Credits: NASA/JPL-Caltech.

NASA’s Juno spacecraft has sent back the first-ever images of Jupiter’s north pole, taken during the spacecraft’s first flyby of the planet with its instruments switched on. The images show storm systems and weather activity unlike anything previously seen on any of our solar system’s gas-giant planets.

Juno successfully executed the first of 36 orbital flybys on Aug. 27 when the spacecraft came about 2,500 miles (4,200 kilometers) above Jupiter’s swirling clouds. The download of six megabytes of data collected during the six-hour transit, from above Jupiter’s north pole to below its south pole, took one-and-a-half days. While analysis of this first data collection is ongoing, some unique discoveries have already made themselves visible.

Image above: NASA's Juno spacecraft captured this view as it closed in on Jupiter's north pole, about two hours before closest approach on Aug. 27, 2016. Image Credits: NASA/JPL-Caltech/SwRI/MSSS.

“First glimpse of Jupiter’s north pole, and it looks like nothing we have seen or imagined before,” said Scott Bolton, principal investigator of Juno from the Southwest Research Institute in San Antonio. “It’s bluer in color up there than other parts of the planet, and there are a lot of storms. There is no sign of the latitudinal bands or zone and belts that we are used to -- this image is hardly recognizable as Jupiter. We’re seeing signs that the clouds have shadows, possibly indicating that the clouds are at a higher altitude than other features.”

One of the most notable findings of these first-ever pictures of Jupiter’s north and south poles is something that the JunoCam imager did not see.

Image above: Juno was about 48,000 miles (78,000 kilometers) above Jupiter's polar cloud tops when it captured this view, showing storms and weather unlike anywhere else in the solar system. Image Credits: NASA/JPL-Caltech/SwRI/MSSS.

“Saturn has a hexagon at the north pole,” said Bolton. “There is nothing on Jupiter that anywhere near resembles that. The largest planet in our solar system is truly unique. We have 36 more flybys to study just how unique it really is.”

Along with JunoCam snapping pictures during the flyby, all eight of Juno’s science instruments were energized and collecting data. The Jovian Infrared Auroral Mapper (JIRAM), supplied by the Italian Space Agency, acquired some remarkable images of Jupiter at its north and south polar regions in infrared wavelengths.

Image above: This infrared image from Juno provides an unprecedented view of Jupiter's southern aurora. Such views are not possible from Earth. Image Credits: NASA/JPL-Caltech/SwRI/MSSS.

“JIRAM is getting under Jupiter’s skin, giving us our first infrared close-ups of the planet,” said Alberto Adriani, JIRAM co-investigator from Istituto di Astrofisica e Planetologia Spaziali, Rome. “These first infrared views of Jupiter’s north and south poles are revealing warm and hot spots that have never been seen before. And while we knew that the first-ever infrared views of Jupiter's south pole could reveal the planet's southern aurora, we were amazed to see it for the first time. No other instruments, both from Earth or space, have been able to see the southern aurora. Now, with JIRAM, we see that it appears to be very bright and well-structured. The high level of detail in the images will tell us more about the aurora’s morphology and dynamics.”

Among the more unique data sets collected by Juno during its first scientific sweep by Jupiter was that acquired by the mission’s Radio/Plasma Wave Experiment (Waves), which recorded ghostly-sounding transmissions emanating from above the planet. These radio emissions from Jupiter have been known about since the 1950s but had never been analyzed from such a close vantage point.

Juno Listens to Jupiter's Auroras

Video above: Thirteen hours of radio emissions from Jupiter's intense auroras are presented here, both visually and in sound.

“Jupiter is talking to us in a way only gas-giant worlds can,” said Bill Kurth, co-investigator for the Waves instrument from the University of Iowa, Iowa City. “Waves detected the signature emissions of the energetic particles that generate the massive auroras which encircle Jupiter’s north pole. These emissions are the strongest in the solar system. Now we are going to try to figure out where the electrons come from that are generating them.”

Jupiter's Glow in Infrared Light

Video above: As Juno approached Jupiter on August 27, 2016, it's Jovian Infrared Auroral Mapper (JIRAM) instrument captured the planet's glow in infrared light.

The Juno spacecraft launched on Aug. 5, 2011, from Cape Canaveral, Florida and arrived at Jupiter on July 4, 2016. JPL manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. Juno is part of NASA's New Frontiers Program, which is managed at NASA's Marshall Space Flight Center in Huntsville, Alabama, for NASA's Science Mission Directorate. Lockheed Martin Space Systems, Denver, built the spacecraft. Caltech in Pasadena, California, manages JPL for NASA.

More information on the Juno mission is available at these sites:


The public can follow the mission on Facebook and Twitter at:

Images (mentioned), Videos, Text, Credits: NASA/Dwayne Brown/Laurie Cantillo/Tony Greicius/JPL/DC Agle.


Hubble's Best Image of Alpha Centauri A and B

NASA - Hubble Space Telescope patch.

Sept. 2, 2016

The closest star system to the Earth is the famous Alpha Centauri group. Located in the constellation of Centaurus (The Centaur), at a distance of 4.3 light-years, this system is made up of the binary formed by the stars Alpha Centauri A and Alpha Centauri B, plus the faint red dwarf Alpha Centauri C, also known as Proxima Centauri.

This NASA/ESA Hubble Space Telescope has given us this stunning view of the bright Alpha Centauri A (on the left) and Alpha Centauri B (on the right), shining like huge cosmic headlamps in the dark. The image was captured by the Wide-Field and Planetary Camera 2 (WFPC2). WFPC2 was Hubble’s most used instrument for the first 13 years of the space telescope’s life, being replaced in 2009 by Wide-Field Camera 3 (WFC3) during Servicing Mission 4. This portrait of Alpha Centauri was produced by observations carried out at optical and near-infrared wavelengths.

Compared to the sun, Alpha Centauri A is of the same stellar type, G2, and slightly bigger, while Alpha Centauri B, a K1-type star, is slightly smaller. They orbit a common center of gravity once every 80 years, with a minimum distance of about 11 times the distance between Earth and the sun. Because these two stars are, together with their sibling Proxima Centauri, the closest to Earth, they are among the best studied by astronomers. And they are also among the prime targets in the hunt for habitable exoplanets.

Hubble and the sunrise over Earth.

Using the European Space Organization's HARPS instrument, astronomers already discovered a planet orbiting Alpha Centauri B.  Then on Aug. 24, 2016, astronomers announced the intriguing discovery of a nearly Earth-sized planet in the habitable zone orbiting the star Proxima Centauri.

Related articles:

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Planet Found in Habitable Zone Around Nearest Star

A spacecraft the size of a smartphone launched to 60'000 Km/s to Alpha Centauri

For more information about the Hubble Space Telescope, visit:

Image, Video, credits: ESA/NASA/Text credits: European Space Agency/NASA/Ashley Morrow.

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jeudi 1 septembre 2016

Images From Sun’s Edge Reveal Origins of Solar Wind

NASA - STEREO Mission logo.

Sept. 1, 2016

Ever since the 1950s discovery of the solar wind – the constant flow of charged particles from the sun – there’s been a stark disconnect between this outpouring and the sun itself. As it approaches Earth, the solar wind is gusty and turbulent. But near the sun where it originates, this wind is structured in distinct rays, much like a child’s simple drawing of the sun. The details of the transition from defined rays in the corona, the sun’s upper atmosphere, to the solar wind have been, until now, a mystery.

Using NASA’s Solar Terrestrial Relations Observatory, or STEREO, scientists have for the first time imaged the edge of the sun and described that transition, where the solar wind starts. Defining the details of this boundary helps us learn more about our solar neighborhood, which is bathed throughout by solar material – a space environment that we must understand to safely explore beyond our planet. A paper on the findings was published in The Astrophysical Journal on Sept. 1, 2016:

Snapshots from the Edge of the Sun

Video above: The details of the transition from defined rays in the corona, the sun’s upper atmosphere, to the solar wind have always been a mystery. Using NASA’s Solar Terrestrial Relations Observatory, or STEREO, scientists have for the first time imaged the edge of the sun and described that transition, where the solar wind starts. Video Credits: NASA’s Goddard Space Flight Center/Genna Duberstein.

“Now we have a global picture of solar wind evolution,” said Nicholeen Viall, a co-author of the paper and a solar scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “This is really going to change our understanding of how the space environment develops.”

Both near Earth and far past Pluto, our space environment is dominated by activity on the sun. The sun and its atmosphere are made of plasma – a mix of positively and negatively charged particles which have separated at extremely high temperatures, that both carries and travels along magnetic field lines. Material from the corona streams out into space, filling the solar system with the solar wind.

But scientists found that as the plasma travels further away from the sun, things change: The sun begins to lose magnetic control, forming the boundary that defines the outer corona – the very edge of the sun.

“As you go farther from the sun, the magnetic field strength drops faster than the pressure of the material does,” said Craig DeForest, lead author of the paper and a solar physicist at the Southwest Research Institute in Boulder, Colorado. “Eventually, the material starts to act more like a gas, and less like a magnetically structured plasma.”

The breakup of the rays is similar to the way water shoots out from a squirt gun. First, the water is a smooth and unified stream, but it eventually breaks up into droplets, then smaller drops and eventually a fine, misty spray. The images in this study capture the plasma at the same stage where a stream of water gradually disintegrates into droplets.

Animation above: Conceptual animation (not to scale) showing the sun's corona and solar wind. Animation Credits: NASA's Goddard Space Flight Center/Lisa Poje.

Before this study, scientists hypothesized that magnetic forces were instrumental to shaping the edge of the corona. However, the effect has never previously been observed because the images are so challenging to process. Twenty million miles from the sun, the solar wind plasma is tenuous, and contains free-floating electrons which scatter sunlight. This means they can be seen, but they are very faint and require careful processing.

In order to resolve the transition zone, scientists had to separate the faint features of the solar wind from the background noise and light sources over 100 times brighter: the background stars, stray light from the sun itself and even dust in the inner solar system. In a way, these images were hiding in plain sight.

Animation above: Views of the solar wind from NASA's STEREO spacecraft (left) and after computer processing (right). Scientists used an algorithm to dim the appearance of bright stars and dust in images of the faint solar wind. This innovation enabled them to see the transition from the corona to the solar wind. It also gives us the first video of the solar wind itself in a previously unmapped region. Animation Credits: data from Craig DeForest, SwRI.

Images of the corona fading into the solar wind are crucial pieces of the puzzle to understanding the whole sun, from its core to the edge of the heliosphere, the region of the sun’s vast influence. With a global perspective, scientists can better understand the large-scale physics at this critical region, which affect not only our planet, but also the entire solar system.

Animation above: Computer-processed data of the solar wind. Animation Credits: data from Craig DeForest, SwRI.

Such observations from the STEREO mission – which launched in 2006 – also help inform the next generation of sun-watchers. In 2018, NASA is scheduled to launch the Solar Probe Plus mission, which will fly into the sun’s corona, collecting more valuable information on the origin and evolution of the solar wind.

STEREO is the third mission in NASA Heliophysics Division’s Solar Terrestrial Probes program, which is managed by Goddard for the Science Mission Directorate, in Washington, D.C.

Related Links:

Image resources available at NASA's Scientific Visualization Studio:

STEREO Mission Overview:

Understanding the Magnetic Sun:

STEREO (Solar TErrestrial RElations Observatory):

Space Weather:

NASA’s Goddard Space Flight Center, by Lina Tran/Rob Garner.

Ceres' Geological Activity, Ice Revealed in New Research

NASA - Dawn Mission patch.

Sept. 1, 2016

Image above: Ceres' lonely mountain, Ahuna Mons, is seen in this simulated perspective view. The elevation has been exaggerated by a factor of two. The view was made using enhanced-color images from NASA's Dawn mission. Image Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI.

A lonely 3-mile-high (5-kilometer-high) mountain on Ceres is likely volcanic in origin, and the dwarf planet may have a weak, temporary atmosphere. These are just two of many new insights about Ceres from NASA's Dawn mission published this week in six papers in the journal Science.

"Dawn has revealed that Ceres is a diverse world that clearly had geological activity in its recent past,” said Chris Russell, principal investigator of the Dawn mission, based at the University of California, Los Angeles.

A Temporary Atmosphere

A surprising finding emerged in the paper led by Russell: Dawn may have detected a weak, temporary atmosphere. Dawn's gamma ray and neutron (GRaND) detector observed evidence that Ceres had accelerated electrons from the solar wind to very high energies over a period of about six days. In theory, the interaction between the solar wind's energetic particles and atmospheric molecules could explain the GRaND observations.

A temporary atmosphere would be consistent with the water vapor the Herschel Space Observatory detected at Ceres in 2012-2013. The electrons that GRaND detected could have been produced by the solar wind hitting the water molecules that Herschel observed, but scientists are also looking into alternative explanations.

"We're very excited to follow up on this and the other discoveries about this fascinating world," Russell said.

Image above: The small, bright crater Oxo (6 miles, 10 kilometers wide) on Ceres is seen in this perspective view. The elevation has been exaggerated by a factor of two. The view was made using enhanced-color images from NASA's Dawn mission. Image Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI.

Ahuna Mons as a Cryovolcano

Ahuna Mons is a volcanic dome unlike any seen elsewhere in the solar system, according to a new analysis led by Ottaviano Ruesch of NASA's Goddard Space Flight Center, Greenbelt, Maryland, and the Universities Space Research Association. Ruesch and colleagues studied formation models of volcanic domes, 3-D terrain maps and images from Dawn, as well as analogous geological features elsewhere in our solar system. This led to the conclusion that the lonely mountain is likely volcanic in nature. Specifically, it would be a cryovolcano -- a volcano that erupts a liquid made of volatiles such as water, instead of silicates. "This is the only known example of a cryovolcano that potentially formed from a salty mud mix, and that formed in the geologically recent past," Ruesch said.

For more details on this study, see:

Young Cryovolcano on Ceres

Video above: Analysis of images from NASA's Dawn mission reveals that dwarf planet Ceres hosts an unexpectedly young cryovolcano that formed with the past billion years. Video Credits: NASA Goddard/Katrina Jackson, Producer/Dawn mission.

Ceres: Between a Rocky and Icy Place

While Ahuna Mons may have erupted liquid water in the past, Dawn has detected water in the present, as described in a study led by Jean-Philippe Combe of the Bear Fight Institute, Winthrop, Washington. Combe and colleagues used Dawn's visible and

infrared mapping spectrometer (VIR) to detect probable water ice at Oxo Crater, a small, bright, sloped depression at mid-latitudes on Ceres.

Exposed water-ice is rare on Ceres, but the low density of Ceres, the impact-generated flows and the very existence of Ahuna Mons suggest that Ceres' crust does contain a significant component of water-ice. This is consistent with a study of Ceres' diverse geological features led by Harald Hiesinger of the Westfälische Wilhelms-Universität, Münster, Germany. The diversity of geological features on Ceres is further explored in a study led by Debra Buczkowski of the Johns Hopkins Applied Physics Laboratory, Laurel, Maryland.

Impact craters are clearly the most abundant geological feature on Ceres, and their different shapes help tell the intricate story of Ceres' past. Craters that are roughly polygonal -- that is, shapes bounded by straight lines -- hint that Ceres' crust is heavily fractured. In addition, several Cerean craters have patterns of visible fractures on their floors.

Image above: This side-perspective view of Ceres' mysterious mountain Ahuna Mons was made with images from NASA's Dawn spacecraft. Image Credits: NASA/JPL/Dawn mission.

Some, like tiny Oxo, have terraces, while others, such as the large Urvara Crater (106 miles, 170 kilometers wide), have central peaks. There are craters with flow-like features, and craters that imprint on other craters, as well as chains of small craters. Bright areas are peppered across Ceres, with the most reflective ones in Occator Crater. Some crater shapes could indicate water-ice in the subsurface.

The dwarf planet's various crater forms are consistent with an outer shell for Ceres that is not purely ice or rock, but rather a mixture of both -- a conclusion reflected in other analyses. Scientists also calculated the ratio of various craters' depths to diameters, and found that some amount of crater relaxation must have occurred. Additionally, there are more craters in the northern hemisphere of Ceres than the south, where the large Urvara and Yalode craters are the dominant features.

"The uneven distribution of craters indicates that the crust is not uniform, and that Ceres has gone through a complex geological evolution," Hiesinger said.

Distribution of Surface Materials

What are the rocky materials in Ceres' crust? A study led by Eleonora Ammannito of the University of California, Los Angeles, finds that clay-forming minerals called phyllosilicates are all over Ceres. These phyllosilicates are rich in magnesium and also have some ammonium embedded in their crystalline structure. Their distribution throughout the dwarf planet's crust indicates Ceres' surface material has been altered by a global process involving water.

Although Ceres' phyllosilicates are uniform in their composition, there are marked differences in how abundant these materials are on the surface. For example, phyllosilicates are especially prevalent in the region around the smooth, "pancake"-like crater Kerwan (174 miles, 280 kilometers in diameter), and less so at Yalode Crater (162 miles, 260 kilometers in diameter), which has areas of both smooth and rugged terrain around it. Since Kerwan and Yalode are similar in size, this may mean that the composition of the material into which they impacted may be different. Craters Dantu and Haulani both formed recently in geologic time, but also seem to differ in composition.

Image above: Ceres' mysterious mountain Ahuna Mons is seen in this mosaic of images from NASA's Dawn spacecraft. On its steepest side, this mountain is about 3 miles (5 kilometers) high. Its average overall height is 2.5 miles (4 kilometers). The diameter of the mountain is about 12 miles (20 kilometers). Dawn took these images from its low-altitude mapping orbit, 240 miles (385 kilometers) above the surface, in December 2015. Image Credits: NASA/JPL/Dawn mission.

"In comparing craters such as Dantu and Haulani, we find that their different material mixtures could extend beneath the surface for miles, or even tens of miles in the case of the larger Dantu," Ammannito said.

Looking Higher

Now in its extended mission, the Dawn spacecraft has delivered a wealth of images and other data from its current perch at 240 miles (385 kilometers) above Ceres' surface, which is closer to the dwarf planet than the International Space Station is to Earth. The spacecraft will be increasing its altitude at Ceres on Sept. 2, as scientists consider questions that can be examined from higher up.

Dawn's mission is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit:

More information about Dawn is available at the following sites:

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

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Astronauts Conclude Second Spacewalk of Expedition 48

ISS - Expedition 48 Mission patch.

September 1, 2016

Two NASA astronauts switched their spacesuits to battery power this morning at 7:53 a.m. EDT aboard the International Space Station to begin a spacewalk planned to last approximately six-and-a-half hours. Expedition 48 Commander Jeff Williams and Flight Engineer Kate Rubins will retract a thermal radiator, install the first of several enhanced high definition cameras on the station’s truss and tighten bolts on a joint that enables one of the station’s solar arrays to rotate.

Image above: Spacewalkers Jeff Williams and Kate Rubins completed the second spacewalk of the Expedition 48 mission. Image Credit: NASA TV.

Williams is EV1, his helmet camera is #17, and he is wearing the spacesuit with a red stripe. Rubins is EV2, her helmet camera is #20, and she is wearing the spacesuit with no stripes.

NASA Astronauts Conduct Second Spacewalk in Two Weeks Outside the Space Station

Expedition 48 Commander Jeff Williams and Flight Engineer Kate Rubins concluded their spacewalk at 2:41 p.m. EDT.  During the six-hour, 48-minute spacewalk, the two NASA astronauts successfully retracted a thermal radiator, installed two enhanced high definition cameras on the station’s truss and tightened bolts on a joint that enables one of the station’s solar arrays to rotate.

Image above: Astronaut Jeff Williams is pictured during the Aug. 19 spacewalk to install an international docking adapter. Image Credit: NASA TV.

Space station crew members have conducted 195 spacewalks in support of assembly and maintenance of the orbiting laboratory. Spacewalkers have now spent a total of 1,217 hours and 34 minutes working outside the station.

Related article:

Spacewalk Concludes After Commercial Crew Port Installation

Keep up with the International Space Station, and its research and crews, at:

International Space Station (ISS):

Space Station Research and Technology:

Images (mentioned), Video, Text, Credits: NASA/Mark Garcia/NASA TV.

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Dawn Sets Course for Higher Orbit

NASA - Dawn Mission patch.

September 01, 2016

After studying Ceres for more than eight months from its low-altitude science orbit, NASA's Dawn spacecraft will move higher up for different views of the dwarf planet.

Dawn has delivered a wealth of images and other data from its current perch at 240 miles (385 kilometers) above Ceres' surface, which is closer to the dwarf planet than the International Space Station is to Earth. Now, the mission team is pivoting to consider science questions that can be examined from higher up.

After Dawn completed its prime mission on June 30, having surpassed all of its scientific objectives at Vesta and at Ceres, NASA extended the mission to perform new studies of Ceres. One of the factors limiting Dawn's lifetime is the amount of hydrazine, the propellant needed to orient the spacecraft to observe Ceres and communicate with Earth. By going to a higher orbit at Ceres, Dawn will use the remaining hydrazine more sparingly, because it won't have to work as hard to counter Ceres' gravitational pull.

Dawn Fires Its Engine Above Ceres (Artist Concept)

Image above: This artist concept shows NASA's Dawn spacecraft above dwarf planet Ceres, as seen in images from the mission. Image Credits: NASA/JPL-Caltech.

"Most spacecraft wouldn't be able to change their orbital altitude so easily. But thanks to Dawn's uniquely capable ion propulsion system, we can maneuver the ship to get the greatest scientific return from the mission," said Marc Rayman, chief engineer and mission director, based at NASA's Jet Propulsion Laboratory, Pasadena, California.

On Sept. 2, Dawn will begin spiraling upward to about 910 miles (1,460 kilometers) from Ceres. The altitude will be close to where Dawn was a year ago, but the orientation of the spacecraft's orbit -- specifically, the angle between the orbit plane and the sun -- will be different this time, so the spacecraft will have a different view of the surface.

The mission team is continuing to develop the extended mission itinerary and will submit a full plan to NASA next month.

Dawn's mission is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit:

More information about Dawn is available at the following sites:

Image (mentioned), Text, Credits: NASA/JPL/Elizabeth Landau.


SpaceX - AMOS-6 Mission - Anomaly Updates

SpaceX logo.

September 01, 2016

Below are updates regarding the anomaly that occurred in preparation for the AMOS-6 mission:

September 1, 1:28pm EDT 

A SpaceX Falcon 9 rocket explodes during fueling operation

At approximately 9:07 am ET, during a standard pre-launch static fire test for the AMOS-6 mission, there was an anomaly at SpaceX’s Cape Canaveral Space Launch Complex 40 resulting in loss of the vehicle.

The anomaly originated around the upper stage oxygen tank and occurred during propellant loading of the vehicle. Per standard operating procedure, all personnel were clear of the pad and there were no injuries.

SpaceX - Static Fire Anomaly - AMOS-6

We are continuing to review the data to identify the root cause. Additional updates will be provided as they become available.

September 1, 10:22am EDT

SpaceX can confirm that in preparation for today's static fire, there was an anomaly on the pad resulting in the loss of the vehicle and its payload. Per standard procedure, the pad was clear and there were no injuries.

AMOS-6 satellite

AMOS-6 satellite made by Israel was designed to ensure Africa Internet coverage to Facebook (the customer).

Israel Aerospace Industries:

For more information about SpaceX, visit:

Images, Video, Text, Credits: SpaceX/US Launch Report/Israel Aerospace Industries/ Aerospace.


mercredi 31 août 2016

New Horizons Spies a Kuiper Belt Companion

NASA - New Horizons Mission logo.

Aug. 31, 2016

NASA’s New Horizons is doing some sightseeing along the way, as the spacecraft speeds toward a New Year’s Day 2019 date with an ancient object in the distant region beyond Pluto known as 2014 MU69.

New Horizons recently observed the Kuiper Belt object Quaoar (“Kwa-war”), which – at 690 miles or 1,100 kilometers in diameter – is roughly half the size of Pluto. This animated sequence shows composite images taken by New Horizons’ Long Range Reconnaissance Imager (LORRI) at four different times over July 13-14: “A” on July 13 at 02:00 Universal Time; “B” on July 13 at 04:08 UT; “C” on July 14 at 00:06 UT; and “D” on July 14 at 02:18 UT. Each composite includes 24 individual LORRI images, providing a total exposure time of 239 seconds and making the faint object easier to see.

New Horizons’ location in the Kuiper Belt gives the spacecraft a uniquely oblique view of the small planets like Quaoar orbiting so far from the sun. When these images were taken, Quaoar was approximately 4 billion miles (6.4 billion kilometers) from the sun and 1.3 billion miles (2.1 billion kilometers) from New Horizons.  With the oblique view available from New Horizons, LORRI sees only a portion of Quaoar’s illuminated surface, which is very different from the nearly fully illuminated view of the Kuiper Belt object from Earth. Comparing Quaoar from the two very different perspectives gives mission scientists a valuable opportunity to study the light-scattering properties of Quaoar’s surface.

New Horizons probe in deep space

In addition to many background stars, two far away galaxies – IC 1048 and UGC 09485, each about 370 billion times farther from New Horizons than Quaoar – are also visible in these images. Unlike the galaxies and stars, Quaoar appears to move across the background scene due to its much closer distance. Other objects which appear to move in these images are camera artifacts.

In June the New Horizons mission received the go-ahead to fly onward to 2014 MU69 -- considered one of the early building blocks of the solar system -- with a planned rendezvous of Jan. 1, 2019.

Related link:

Kuiper Belt:

For more information about New Horizons, visit:

Animation, Image, Text, Credits: NASA/JHUAPL/SwRI/Tricia Talbert.


Pluto’s Methane Snowcaps on the Edge of Darkness

NASA - New Horizons Mission logo.

Aug. 31, 2016

The southernmost part of Pluto that NASA’s New Horizons spacecraft could “see” during closest approach in July 2015 contains a range of fascinating geological features, and offers clues into what might lurk in the regions shrouded in darkness during the flyby.

The area shown above is south of Pluto’s dark equatorial band informally named Cthulhu Regio, and southwest of the vast nitrogen ice plains informally named Sputnik Planum or Sputnik Planitia, as the mission team recently redesignated the area to more accurately reflect the low elevation of the plains. North is at the top; in the western portion of the image, a chain of bright mountains extends north into Cthulhu Regio. The mountains reveal themselves as snowcapped—something hauntingly familiar from our Earthbased experience. But New Horizons compositional data indicate the bright snowcap material covering these mountains isn’t water, but atmospheric methane that has condensed as frost onto these surfaces at high elevation. Between some mountains are sharply cut valleys – indicated by the white arrows below. These valleys are each a few miles across and tens of miles long.

A similar valley system in the expansive plains to the east (blue arrows) appears to be branched, with smaller valleys leading into it. New Horizons scientists think flowing nitrogen ice that once covered this area -- perhaps when the ice in Sputnik was at a higher elevation -- may have formed these valleys. The area is also marked by irregularly shaped, flat-floored depressions (green arrows) that can reach more than 50 miles (80 kilometers) across and almost 2 miles (3 kilometers) deep. The great widths and depths of these depressions suggest that they may have formed when the surface collapsed, rather than through the sublimation of ice into the atmosphere.

For more information about New Horizons, visit:

Images, Text, Credits: NASA/JHUAPL/SwRI/Tricia Talbert.

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XMM-Newton reveals the Milky Way's explosive past

ESA - XMM-Newton Mission patch.

31 August 2016

A giant bubble surrounding the centre of the Milky Way shows that six million years ago our Galaxy's supermassive black hole was ablaze with furious energy. It also shines a light on the hiding place of the Galaxy's so-called 'missing' matter.

While the mysterious dark matter grabs most of the headlines, astronomers also know that they have yet to find all of the normal, so-called baryonic, matter in the Galaxy. That has now changed thanks to the work of ESA's X-ray observatory XMM-Newton.

A thorough analysis of archival observations has shown that there is a vast quantity of baryonic matter scattered through the Galaxy. XMM-Newton found it in the form of gas at a temperature of one million degrees that permeates both the disc of the Galaxy, where the majority of the stars are found, and a spherical volume that surrounds the whole Galaxy.

Image above: Artistic representation of our Milky Way galaxy during an active phase. Image Credits: Mark A. Garlick/CfA.

The spherical cloud is vast. Whereas the Sun lies just 26 000 light years from the centre of the Galaxy, the cloud extends out to a distance of at least 200 000 – 650 000 light years.

Fabrizio Nicastro, from the Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Roma, Italy, and his colleagues have been on the trail of the missing baryons for more than 15 years now. Their latest discovery with XMM-Newton shows that there is enough million-degree-hot gas in the Galaxy to account for it all.

It has remained undetected for so long because it does not emit visible light. Instead, the astronomers found it because the oxygen in the cloud absorbed X-rays at very specific wavelengths from light being emitted by more distant celestial objects.

And this was not the only discovery waiting in the data for the team. When it came to model the data with computer simulations to understand the way in which the gas was distributed around the Galaxy, the team did not get the answer they were expecting.

"According to simple gravitational physics you expect the density of the gas to decrease from the centre outwards," says Nicastro. In this picture, the density of gas will be at its peak in the centre of the Galaxy and at its least on the outer edges. But there was a hitch. "I spent three months trying to match the data with that model and I just couldn't," says Nicastro.

Having tried everything else, he moved the peak density away from the centre of the Galaxy. At a distance of about 20 000 light years from the Galaxy's centre the model fitted better. It was puzzling why this should improve things until he remembered that this distance is also the size of two large 'balloons' of gamma rays found in 2010 by NASA's Fermi gamma-ray observatory, which extend tens of thousands of light-years above and below the centre of our Galaxy.

So Nicastro constructed a different density model, in which there was a central bubble of low density gas extending out to 20 000 light years. When he applied this model to his X-ray data, he found that it fitted excellently.

"That was unexpected and very exciting at the same time," says Nicastro. It meant that something had pushed the gas outwards from the centre of the Galaxy, creating a giant bubble.

Astronomers know that there is a supermassive black hole at the centre of our Galaxy. It lies silent and dark these days but the bubble indicates that six million years ago things were very different.

The supermassive black hole was pulling stars and gas clouds to pieces and swallowing the contents. En route to annihilation, the doomed matter was heating up and releasing vast quantities of energy that snow-ploughed through the halo gas, opening up the bubble.

When astronomers look out into the wider Universe, they see that a small percentage of galaxies contain an extremely bright core. These cores are called active galactic nuclei, and as a result of this study astronomers now know that our Milky Way once had one of them.

XMM-Newton X-ray Observatory. Image Credit: ESA

Six million years later, the shock wave created by this activity has crossed 20 000 light-years of space, creating the bubble that XMM-Newton has seen. Meanwhile, the supermassive black hole has run out of nearby food and gone quiet again.

"I think the evidence for the Milky Way having been more active in the past is now strong," says Nicastro.

"We have taken a big step forwards with this result," says Norbert Schartel, ESA Project Scientist for XMM-Newton. "It means that the next generation of X-ray telescopes, such as ESA's ATHENA mission, will have plenty to study following its launch in 2028."
Notes for editors

A Distant Echo of Milky Way Central Activity closes the Galaxy's Baryon Census by F. Nicastro et al. 2016 is published in ApJL, 828, L12 (doi:10.3847/2041-8205/828/1/L12). A PDF of the accepted paper can be found at:

The European Space Agency's X-ray Multi-Mirror Mission, XMM-Newton, was launched in December 1999. The largest scientific satellite to have been built in Europe, it is also one of the most sensitive X-ray observatories ever flown. More than 170 wafer-thin, cylindrical mirrors direct incoming radiation into three high-throughput X-ray telescopes. XMM-Newton's orbit takes it almost a third of the way to the Moon, allowing for long, uninterrupted views of celestial objects.

For more information about XMM-Newton, visit:

Images (mentioned), Text, Credits: European Space Agency (ESA).


Comet dust flyover

ESA - Rosetta Mission patch.

31 August 2016

Rosetta has imaged the smallest grains of Comet 67P/Churyumov-Gerasimenko's dust yet, with its Micro-Imaging Dust Analysis System, MIDAS.

ESA Science & Technology: Comet dust flyover

Video above: Comet dust flyover. Video Credits: ESA/Rosetta/IWF for the MIDAS team IWF/ESA/LATMOS/Universiteit Leiden/Universität Wien.

MIDAS works by collecting and then physically scanning grains with an Atomic Force Microscope. This uses a very fine tip, a bit like an old-fashioned record player needle, that is scanned over a particle. The deflection of the needle and therefore the height of the sample are measured to build up a 3D picture. This enables scientists to determine the structure of the particle, and thus gain insight into how it might have formed.

The new results, published in the journal Nature, provide evidence that dust particles continue to be aggregates below the size range already reported by the COSIMA instrument. That is, even at the very small scales of a few tens of micrometres down to a few hundred nanometres, the dust grains analysed by MIDAS appear to be made up of numerous smaller grains.

Image above: MIDAS particles A, B, and C. Image Credits: ESA/Rosetta/IWF for the MIDAS team IWF/ESA/LATMOS/Universiteit Leiden/Universität Wien.

"To understand how comets are formed, we need to understand the structure of the smallest grains and how they are built," says Mark Bentley of the Space Research Institute at the Austrian Academy of Science in Graz, Austria, principal investigator of MIDAS and lead author of the paper.

"What we see with MIDAS is that everything is made of smaller and smaller aggregates; it's similar to what the COSIMA instrument sees but continued down to even smaller scales."

Image above: MIDAS particle D. Image Credits: ESA/Rosetta/IWF for the MIDAS team IWF/ESA/LATMOS/Universiteit Leiden/Universität Wien.

MIDAS detected both small, tightly packed 'compact' grains and larger more porous, loosely arranged 'fluffy' grains. The comet grains also appear to be elongated, several times longer in one direction than the others, in agreement with observations of dust in the interstellar medium.

Examples of the different types, which were collected by MIDAS from mid-November 2014 to February 2015, are shown in the figures accompanying this article.

Image above: MIDAS particle E - a 'fluffy' aggregate particle. Image Credits: ESA/Rosetta/IWF for the MIDAS team IWF/ESA/LATMOS/Universiteit Leiden/Universität Wien.

One particularly large, porous grain captured from Comet 67P/C-G has similar properties to a type of so-called 'interplanetary dust grain' (IDP) thought to have grown into porous aggregates of smaller spheroidal particles during the early phases of Solar System formation.

These new results from MIDAS further strengthen the link between IDPs and cometary dust. The observed "aggregate of aggregates" structure of the particles gives hints to their formation mechanism, and how such particles could form a weakly bound layer at the surface of the comet nucleus.

"Aggregate dust particles at comet 67P/Churyumov-Gerasimenko" by M. S. Bentley et al. is published in Nature:

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Images (mentioned), Video (mentioned), Text, Credit: European Space Agency (ESA).


First stars formed even later than previously thought

ESA - Planck Mission patch.

31 August 2016

ESA's Planck satellite has revealed that the first stars in the Universe started forming later than previous observations of the Cosmic Microwave Background indicated. This new analysis also shows that these stars were the only sources needed to account for reionising atoms in the cosmos, having completed half of this process when the Universe had reached an age of 700 million years.

Cosmic reionisation. Image Credits: ESA/C. Carreau

With the multitude of stars and galaxies that populate the present Universe, it's hard to imagine how different our 13.8 billion year cosmos was when it was only a few seconds old. At that early phase, it was a hot, dense primordial soup of particles, mostly electrons, protons, neutrinos, and photons – the particles of light.

In such a dense environment the Universe appeared like an 'opaque' fog, as light particles could not travel any significant distance before colliding with electrons.

As the cosmos expanded, the Universe grew cooler and more rarefied and, after about 380 000 years, finally became 'transparent'. By then, particle collisions were extremely sporadic and photons could travel freely across the cosmos.

History of the Universe. Image Credit: ESA

Today, telescopes like Planck can observe this fossil light across the entire sky as the Cosmic Microwave Background, or CMB. Its distribution on the sky reveals tiny fluctuations that contain a wealth of information about the history, composition and geometry of the Universe.

The release of the CMB happened at the time when electrons and protons joined to form hydrogen atoms. This is the first moment in the history of the cosmos when matter was in an electrically neutral state.

After that, a few hundred million years passed before these atoms could assemble and eventually give rise to the Universe's first generation of stars.

As these first stars came to life, they filled their surroundings with light, which subsequently split neutral atoms apart, turning them back into their constituent particles: electrons and protons. Scientists refer to this as the 'epoch of reionisation'. It did not take long for most material in the Universe to become completely ionised, and – except in a very few, isolated places – it has been like that ever since.

Observations of very distant galaxies hosting supermassive black holes indicate that the Universe had been completely reionised by the time it was about 900 million years old. The starting point of this process, however, is much harder to determine and has been a hotly debated topic in recent years.

"The CMB can tell us when the epoch of reionisation started and, in turn, when the first stars formed in the Universe," explains Jan Tauber, Planck project scientist at ESA.

To make this measurement, scientists exploit the fact that a fraction of the CMB is polarised: part of the light vibrates in a preferred direction. This results from CMB photons bouncing off electrons – something that happened very frequently in the primordial soup, before the CMB was released, and then again later, after reionisation, when light from the first stars brought free electrons back onto the cosmic stage.

"It is in the tiny fluctuations of the CMB polarisation that we can see the influence of the reionisation process and deduce when it began," adds Tauber.

Image above: Polarisation of the Cosmic Microwave Background. Image Credits: ESA and the Planck Collaboration.

A first estimate of the epoch of reionisation came in 2003 from NASA's Wilkinson Microwave Anisotropy Probe (WMAP), suggesting that this process might have started early in cosmic history, when the Universe was only a couple of hundred million years old. This result was problematic, because there is no evidence that any stars had formed by then, which would mean postulating the existence of other, exotic sources that could have caused the reionisation at that time.

This first estimate was soon to be corrected, as subsequent data from WMAP pushed the starting time to later epochs, indicating that the Universe had not been significantly reionised until at least some 450 million years into its history.

This eased, but did not completely solve the puzzle: although the earliest of the first stars have been observed to be present already when the Universe was 300 to 400 million years old, it remained unclear whether these stars were the main culprits for reionising fully the cosmos or whether additional, more exotic sources must have played a role too.

In 2015, the Planck Collaboration provided new data to tackle the problem, moving the reionisation epoch even later in cosmic history and revealing that this process was about half-way through when the Universe was around 550 million years old. The result was based on Planck's first all-sky maps of the CMB polarisation, obtained with its Low-Frequency Instrument (LFI).

Now, a new analysis of data from Planck's other detector, the High-Frequency Instrument (HFI), which is more sensitive to this phenomenon than any other so far, shows that reionisation started even later – much later than any previous data have suggested.

"The highly sensitive measurements from HFI have clearly demonstrated that reionisation was a very quick process, starting fairly late in cosmic history and having half-reionised the Universe by the time it was about 700 million years old," says Jean-Loup Puget from Institut d'Astrophysique Spatiale in Orsay, France, principal investigator of Planck's HFI.

"These results are now helping us to model the beginning of the reionisation phase."

"We have also confirmed that no other agents are needed, besides the first stars, to reionise the Universe," adds Matthieu Tristram, a Planck Collaboration scientist at Laboratoire de l'Accélérateur Linéaire in Orsay, France.

Planck Space Telescope. Image Credit: ESA

The new study locates the formation of the first stars much later than previously thought on the cosmic timeline, suggesting that the first generation of galaxies are well within the observational reach of future astronomical facilities, and possibly even some current ones.

In fact, it is likely that some of the very first galaxies have already been detected with long exposures, such as the Hubble Ultra Deep Field observed with the NASA/ESA Hubble Space Telescope, and it will be easier than expected to catch many more with future observatories such as the NASA/ESA/CSA James Webb Space Telescope.

Notes for Editors:
'Planck intermediate results. XLVII. Planck constraints on reionization history' and 'Planck intermediate results. XLVI. Reduction of large-scale systematic effects in HFI polarization maps and estimation of the reionization optical depth' by the Planck Collaboration are published in Astronomy and Astrophysics:

More about Planck:

Launched in 2009, Planck was designed to map the sky in nine frequencies using two state-of-the-art instruments: the Low Frequency Instrument (LFI), which includes three frequency bands in the range 30-70 GHz, and the High Frequency Instrument (HFI), which includes six frequency bands in the range 100-857 GHz.

HFI completed its survey in January 2012, while LFI continued to make science observations until 3 October 2013, before being switched off on 19 October 2013. Seven of Planck's nine frequency channels were equipped with polarisation-sensitive detectors.

The Planck Scientific Collaboration consists of all the scientists who have contributed to the development of the mission, and who participate in the scientific exploitation of the data during the proprietary period.

These scientists are members of one or more of four consortia: the LFI Consortium, the HFI Consortium, the DK-Planck Consortium, and ESA's Planck Science Office. The two European-led Planck Data Processing Centres are located in Paris, France and Trieste, Italy.

The LFI consortium is led by N. Mandolesi, Università degli Studi di Ferrara, Italy (deputy PI: M. Bersanelli, Università degli Studi di Milano, Italy), and was responsible for the development and operation of LFI. The HFI consortium is led by J.L. Puget, Institut d'Astrophysique Spatiale in Orsay (CNRS/Université Paris-Sud), France (deputy PI: F. Bouchet, Institut d'Astrophysique de Paris (CNRS/UPMC), France), and was responsible for the development and operation of HFI.

For more information about Planck mission, visit:

Images (mentioned), Text, Credits: ESA/Jan Tauber/Institut d'Astrophysique Spatiale/Jean-Loup Puget/CNRS - IN2P3, Laboratoire de l'Accélérateur Linéaire, Université Paris-Sud 11/Matthieu Tristram.