vendredi 6 octobre 2017

Juno Observes Jupiter, Io and Europa

NASA - JUNO Mission logo.

Oct. 6, 2017

This color-enhanced image of Jupiter and two of its largest moons – Io and Europa – was captured by NASA’s Juno spacecraft as it performed its eighth flyby of the gas giant planet.

The image was taken on Sept. 1, 2017 at 3:14 p.m. PDT (6:14 p.m. EDT). At the time the image was taken, the spacecraft was about 17,098 miles (27,516 kilometers) from the tops of the clouds of the planet at a latitude of minus 49.372 degrees.

Closer to the planet, the Galilean moon of Io can be seen at an altitude of 298,880 miles (481,000 kilometers) and at a spatial scale of 201 miles (324 kilometers) per pixel. In the distance (to the left), another one of Jupiter's Galilean moons, Europa, is visible at an altitude of 453,601 miles (730,000 kilometers) and at a spatial scale of 305 miles (492 kilometers) per pixel.

Citizen scientist Roman Tkachenko processed this image using data from the JunoCam imager.

JUNO spacecraft orbiting Jupiter

JunoCam's raw images are available for the public to peruse and process into image products at:

More information about Juno is at: and

Image, Animation, Text,  Credits: NASA/Tony Greicius/JPL-Caltech/SwRI/MSSS/Roman Tkachenko.

Best regards,

Hubble's Bubbles in the Tarantula Nebula

NASA - Hubble Space Telescope patch.

Oct. 6, 2017

At a distance of just 160,000 light-years, the Large Magellanic Cloud is one of the Milky Way’s closest companions. It is also home to one of the largest and most intense regions of active star formation known to exist anywhere in our galactic neighborhood — the Tarantula Nebula. This NASA/ESA Hubble Space Telescope image shows both the spindly, spidery filaments of gas that inspired the region’s name, and the intriguing structure of stacked “bubbles” that forms the so-called Honeycomb Nebula (to the lower left).

The Honeycomb Nebula was found serendipitously by astronomers using ESO’s New Technology Telescope to image the nearby SN1987A, the closest observed supernova to Earth for more than 400 years. The nebula’s strange bubble-like shape has baffled astronomers since its discovery in the early 1990s. Various theories have been proposed to explain its unique structure, some more exotic than others.

In 2010, a group of astronomers studied the nebula and, using advanced data analysis and computer modelling, came to the conclusion that its unique appearance is likely due to the combined effect of two supernovae — a more recent explosion has pierced the expanding shell of material created by an older explosion. The nebula’s especially striking appearance is suspected to be due to a fortuitous viewing angle; the honeycomb effect of the circular shells may not be visible from another viewpoint.

Hubble Space Telescope

For images and more information about Hubble, visit:

Image, Animation, Credits: ESA/Hubble & NASA, Acknowledgements: Judy Schmidt (Geckzilla)/Text credits: European Space Agency/NASA/Karl Hille.


Mars Study Yields Clues to Possible Cradle of Life

NASA - Mars Reconnaissance Orbiter (MRO) patch.

Oct. 6, 2017

The discovery of evidence for ancient sea-floor hydrothermal deposits on Mars identifies an area on the planet that may offer clues about the origin of life on Earth.

Image above: This view of a portion of the Eridania region of Mars shows blocks of deep-basin deposits that have been surrounded and partially buried by younger volcanic deposits. The image was taken by the Context Camera on NASA's Mars Reconnaissance Orbiter and covers an area about 12 miles wide. Image Credits: NASA/JPL-Caltech/MSSS.

A recent international report examines observations by NASA's Mars Reconnaissance Orbiter (MRO) of massive deposits in a basin on southern Mars. The authors interpret the data as evidence that these deposits were formed by heated water from a volcanically active part of the planet's crust entering the bottom of a large sea long ago.

"Even if we never find evidence that there's been life on Mars, this site can tell us about the type of environment where life may have begun on Earth," said Paul Niles of NASA's Johnson Space Center, Houston. "Volcanic activity combined with standing water provided conditions that were likely similar to conditions that existed on Earth at about the same time -- when early life was evolving here."

Image above: The Eridania basin of southern Mars is believed to have held a sea about 3.7 billion years ago, with seafloor deposits likely resulting from underwater hydrothermal activity. This graphic shows estimated depths of water in that ancient sea. The map covers an area about 530 miles wide. Image Credit: NASA.

Mars today has neither standing water nor volcanic activity. Researchers estimate an age of about 3.7 billion years for the Martian deposits attributed to seafloor hydrothermal activity. Undersea hydrothermal conditions on Earth at about that same time are a strong candidate for where and when life on Earth began. Earth still has such conditions, where many forms of life thrive on chemical energy extracted from rocks, without sunlight. But due to Earth's active crust, our planet holds little direct geological evidence preserved from the time when life began. The possibility of undersea hydrothermal activity inside icy moons such as Europa at Jupiter and Enceladus at Saturn feeds interest in them as destinations in the quest to find extraterrestrial life.

Observations by MRO's Compact Reconnaissance Spectrometer for Mars (CRISM) provided the data for identifying minerals in massive deposits within Mars' Eridania basin, which lies in a region with some of the Red Planet's most ancient exposed crust.

"This site gives us a compelling story for a deep, long-lived sea and a deep-sea hydrothermal environment," Niles said. "It is evocative of the deep-sea hydrothermal environments on Earth, similar to environments where life might be found on other worlds -- life that doesn't need a nice atmosphere or temperate surface, but just rocks, heat and water."

Image above: This diagram illustrates an interpretation for the origin of some deposits in the Eridania basin of southern Mars as resulting from seafloor hydrothermal activity more than 3 billion years ago. Image Credit: NASA.

Niles co-authored the recent report in the journal Nature Communications with lead author Joseph Michalski, who began the analysis while at the Natural History Museum, London, and  co-authors at the Planetary Science Institute in Tucson, Arizona, and the Natural History Museum.

The researchers estimate the ancient Eridania sea held about 50,000 cubic miles (210,000 cubic kilometers) of water. That is as much as all other lakes and seas on ancient Mars combined and about nine times more than the combined volume of all of North America's Great Lakes. The mix of minerals identified from the spectrometer data, including serpentine, talc and carbonate, and the shape and texture of the thick bedrock layers, led to identifying possible seafloor hydrothermal deposits. The area has lava flows that post-date the disappearance of the sea. The researchers cite these as evidence that this is an area of Mars' crust with a volcanic susceptibility that also could have produced effects earlier, when the sea was present.

The new work adds to the diversity of types of wet environments for which evidence exists on Mars, including rivers, lakes, deltas, seas, hot springs, groundwater, and volcanic eruptions beneath ice.

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

"Ancient, deep-water hydrothermal deposits in Eridania basin represent a new category of astrobiological target on Mars," the report states. It also says, “Eridania seafloor deposits are not only of interest for Mars exploration, they represent a window into early Earth." That is because the earliest evidence of life on Earth comes from seafloor deposits of similar origin and age, but the geological record of those early-Earth environments is poorly preserved.

The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, built and operates CRISM, one of six instruments with which MRO has been examining Mars since 2006. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the project for the NASA Science Mission Directorate in Washington. Lockheed Martin Space Systems of Denver built the orbiter and supports its operations. For more about MRO, visit:

Mars Reconnaissance Orbiter (MRO):

Images (mentioned), Text, Credits: NASA/Laurie Cantillo/Dwayne Brown/JPL/Guy Webster/Johnson Space Center/Jenny Knotts.

Best regards,

jeudi 5 octobre 2017

NASA Finds Heavy Rainfall in Developing Tropical Storm Nate

NASA & JAXA - GPM Mission patch.

Oct. 5, 2017

Nate (was TD16 - Southwestern Caribbean Ocean)

After tropical depression 16 formed in the southwestern Caribbean Sea it continued organizing and strengthening. The Global Precipitation Measurement mission or GPM core satellite flew over the depression and found heavy rainfall. As the depression strengthened into Tropical Storm Nate, that heavy rainfall is expected to occur over a wide area, including locations well away from the center along the Pacific coast of Central America through Friday night, Oct. 6.

Image above: On Oct. 5, the GPM core satellite showed storm tops within powerful convective storms located in rain bands in the northeastern semicircle of TD16 were reaching heights of 9.3 mile (15 km). Image Credits: NASA/JAXA, Hal Pierce.

The National Hurricane Center forecast on Oct. 5 calls for Nicaragua to receive from 15 to 20 inches, isolated 30 inches; Costa Rica and Panama is forecast to receive 5 to 10 inches, isolated 20 inches; Honduras and Eastern portions of the Yucatan Peninsula from 4 to 8 inches, isolated 12 inches; and Belize between 2 to 5 inches, with isolated totals of 8 inches.

The GPM core observatory satellite passed above Tropical Depression 16 (forming tropical storm Nate) on Oct. 5, 2017 at 5:46 a.m. EDT (0946 UTC). At that time, Tropical Depression 16 (TD16) was located in the western Caribbean near the coast of Nicaragua with winds of about 34.5 mph (30 knots). Data received by GPM's Microwave Imager (GMI) and Dual-Frequency Precipitation Radar (DPR) showed bands of rain producing heavy rainfall East of TD16's center of circulation. Downpours in the Caribbean Sea East of Nicaragua were measured by GPM's Radar (DPR Ku Band) dropping rain at a rate of over 6.4 inches (162 mm) per hour.

At NASA's Goddard Space Flight Center in Greenbelt, Maryland a close-up 3-D cross section view (looking toward the southeast) was created that showed rainfall structure near TD16's center. It was created using data that was captured when the GPM satellite's radar (DPR Ku band) scanned precipitation in the center of the tropical cyclone. Storm tops within powerful convective storms located in rain bands in the northeastern semicircle of TD16 were shown by DPR reaching heights of 9.3 mile (15 km). GPM is co-managed by NASA and the Japan Aerospace Exploration Agency.

NASA Examines Tropical Storm Nate's Heavy Rainfall

Video above: On Oct. 5 the GPM core satellite found some of Tropical Depression 16's thunderstorms located over the Caribbean Sea East of Nicaragua were dropping rain at a rate of over 6.4 inches (162 mm) per hour. GPM showed storm tops within powerful convective storms located in rain bands in the northeastern semicircle of TD16 were reaching heights of 9.3 mile (15 km). Video Credits: NASA/JAXA, Hal Pierce.

At 11 a.m. EDT on Oct. 5, the Government of Mexico issued a Tropical Storm Warning for the coast of the Yucatan Peninsula and the adjacent islands from Punta Herrero to Rio Lagartos. A Tropical Storm Warning is in effect for Sandy Bay Sirpi Nicaragua to Punta Castilla Honduras and from Punta Herrero to Rio Lagartos Mexico. A Hurricane Watch is in effect for Punta Herrero to Rio Lagartos Mexico.

At 11 a.m. EDT (1500 UTC), the center of Tropical Storm Nate was located inland over northeastern Nicaragua near 14.3 degrees north latitude and 83.7 degrees west longitude. That's about 30 miles (45 km) northwest of Puerto Cabezas, Nicaragua and about 65 miles (105 km south of Puerto Lempira, Honduras.

Nate was moving toward the northwest near 9 mph (15 kph).  NHC said a turn toward the north-northwest at a faster forward speed is expected later today, with that motion continuing through Friday night.  On the forecast track, the center of Nate should move across northeastern Nicaragua and eastern Honduras today and then over the northwestern Caribbean Sea tonight and Friday. The center is expected to approach the coast of the Yucatan Peninsula late Friday.

Visualization of the GPM Core Observatory and Partner Satellites. Image Credits: NASA/JAXA

Maximum sustained winds are near 40 mph (65 kph) with higher gusts. Little change in strength is expected today while the center is over land.  Strengthening is likely once the center moves over the northwestern Caribbean Sea tonight and Friday, Oct. 6.

The estimated minimum central pressure is 999 millibars. The National Hurricane Center (NHC) indicates that the tropical cyclone's future intensity is uncertain over the next couple days due to interaction with the coasts of Nicaragua, Honduras and then the Yucatan Peninsula.

The tropical cyclone is forecast to strengthen as it moves over the Gulf of Mexico and could threaten the northern Gulf Coast as a category one hurricane this weekend. A recent NHC forecast track indicated that the possible hurricane would most affect coastal areas from Louisiana through the Florida panhandle.

For forecast updates, visit the NHC website:

GPM (Global Precipitation Measurement):

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


The Scientific Quest to Explain Kepler’s Most Enigmatic Find

NASA - Kepler Space Telescope patch.

Oct. 5, 2017

KIC 8462852, nicknamed “Tabby’s Star”. Image Credits: NASA/Ames Research Center

Some 1,500 light years from Earth, a mystery of stellar proportions is playing out. A singular star out there captured scientists’ and the public’s imagination in September 2015 with its strangely fluctuating brightness. Ever since then, the scientific community has been observing this enigmatic character and sifting methodically through the data in search of an answer. Certain explanations are eliminated, while other likely suspects come to the fore. Meanwhile, the world has the chance to watch, as the scientific process and the mystery continue to unfold.

The star under scrutiny is officially known as KIC 8462852, but was nicknamed “Tabby’s Star,” for its discoverer, Tabetha Boyajian, an assistant professor of astrophysics at Louisiana State University in Baton Rouge. It first became famous when data from NASA’s Kepler space telescope revealed that sudden and significant dips in its brightness had occurred in 2011 and 2013. The star’s light dimmed by as much as a whopping 22 percent for days at a time. No other star out of more than 200,000 that Kepler measured during its original, four-year mission behaves in exactly this way.

Image above: A scene like this illustration of dust orbiting the star could be an answer to the mystery of the strangely fluctuating star. Image Credits: NASA/Ames Research Center/Daniel Rutter.

“This [dimming] behavior was not something we were looking for or had trained our algorithms to find,” Boyajian said. "In fact, we were first alerted to the star’s unique activity by citizen scientists participating in the Planet Hunters program."

A Stellar Detective Story

The internet’s favorite theory to explain the strange phenomenon was that this could be a Dyson sphere—a hypothetical structure built by an advanced alien civilization to collect energy from its star. However, new data from NASA’s Spitzer space telescope and the Swift mission, along with a Belgian observatory used by amateur astronomers, provide strong evidence against such a “megastructure.”

These observers were looking at another type of enigmatic behavior from Boyajian’s star: a less extreme, long-term dimming that is also difficult to explain. What they found tells us something about the sudden dips in the star’s light, too: Their results show that a large, solid object like the hypothesized structure would not cause starlight to dim in the precise way the telescopes observed.

The scientific community has actually favored a number of more plausible explanations all along. These scenarios are subjected to the same rigorous assessment: a group of researchers leans toward a particular idea, they make observations of the star, analyze the data, compare their proposed scenario against the findings of other researchers worldwide, and see how it all adds up.

Image above: A ringed planet and asteroids orbiting the star, depicted here, could explain the star's strange behavior. Image Credits: NASA/Ames Research Center/Daniel Rutter.

So far, these investigations have led scientists to rule out multiple hypotheses for the behavior of Boyajian’s star, at least pending any further developments. Yet it’s this process of elimination – scientists working their way through the likely culprits, crossing names off their list, one by one – that will bring us closer to solving the mystery.

The most recent findings, based on the new data from Spitzer and Swift, point the finger at an uneven dust cloud orbiting the star to explain the long, slow dimming of the star, which may prove related to the short dips in brightness. As for the latter, one study has suggested that a star orbited by a ringed planet and clusters of asteroids could exhibit the same strange dimming behavior. Yet another has considered a planet being pulled apart and swallowed up by the star. These relative newcomers to the mystery have followed other explanations previously put on trial by scientists for the strange behavior of Boyajian’s star. Here are a few of the “accused,” and the evidence that exonerated them.

Could it be a swarm of comets?

One explanation for Boyajian’s star’s mysterious short-term dimming behavior could be a swarm of comets – hundreds of them, at least – passing in front of the star. Such a large amount of debris could be capable of blocking enough light to dim the star considerably, and at irregular intervals, but here, too, it has thrown scientists a curve ball. The temperature of all the dust and debris associated with a horde of disintegrating comets should make it glow in the infrared – something the Spitzer telescope would be able to see. Spitzer, however, found no excess infrared radiation.

Image above: A planet being torn apart and swallowed by a star, shown in the cartoon image above, is another potential explanation. Image Credits: NASA/Ames Research Center/Daniel Rutter.

What about an object eclipsing the star?

Could it be a large object passing in front of the star? This is the type of dimming that Kepler was designed to detect in its hunt for exoplanets: like a mini-eclipse, a planet crossing the face of its star will cause a tiny, but observable, decrease in the brightness. In this case, though, the extreme dimming events would require a star-sized object, and the gravitational force exerted on Boyajian’s star by such a companion would be obvious in follow-up observations. Nothing has been detected so far.

Image above: A cartoon image of what an object eclipsing the mysterious star could look like. Image Credits: NASA/Ames Research Center/Daniel Rutter.

“When I first saw the data, I was immediately reminded of the eclipsing triple-star systems discovered by Kepler – systems like KOI-126, which show similar patterns of irregular, eclipse-like dimmings,” said Natalie Batalha, an astrophysicist at NASA’s Ames Research Center in California’s Silicon Valley. But, again, a star engaged in such a complicated relationship would feel the gravitational pull of its partners, bringing a strange rhythm to its dance: a systematic wobble of the center of mass of the system. “I was very surprised to learn that follow-up measurements with ground-based telescopes revealed no evidence of a stellar-mass companion.”

Is the star just burning out?

Despite the subtle, long-term dimming observed, this is not a matter of the lights simply going out at Boyajian’s star. Astronomers have determined this is a type of star that is fusing hydrogen into helium in its core. Given that fact and where it is in its expected lifetime, it should be gradually brightening, not growing fainter.

Image above: An artist’s rendition of a potential explanation: a comet swarm orbiting the star KIC 8462852, also known as Boyajian's Star or Tabby's Star. Image Credits: NASA/Ames Research Center/Daniel Rutter.

Apart from its long-term evolution, a star’s magnetic activity – which produces sunspots – does go through shorter cycles, creating some ups and downs in brightness. However, the extent of those changes and the timescale on which they occur are not comparable to this one’s sudden, dramatic dips. For example, the brightness of our sun may decrease periodically, but that’s a change on the order of just one-tenth of one percent over its 11-year solar cycle.

Was there simply an instrument glitch?

Some observers questioned if an instrument glitch could be responsible for the strange data on Boyajian’s star. No, says Doug Caldwell, SETI Institute researcher and instrument scientist for the Kepler mission at Ames—for two reasons. First, the results are the same, regardless of which of the telescope’s detectors were observing the star, ruling out a defect on the lens of the photometer, or the on-board camera. Second, the enormous drops in brightness were already visible in every single pixel attributed to this star in the Kepler images. Usually, all those pixels need to be added together and the total brightness of a star measured, in order to detect a change; if any pixels belonging to another star are mistakenly included, this can create a false positive. That was clearly not the case here.

Image above: An illustration of the Kepler spacecraft and its sensors. Researchers considered whether an instrument glitch could explain the dimming. Image Credits: NASA/Ames Research Center/Daniel Rutter.

So far, no warrant has yet been issued for any one explanation’s arrest, and so the hunt goes on.

Keeping Many Eyes on the Star

With the case of Boyajian’s star still open, scientists continue to ask What if…?, and adjust their ideas according to what the data reveals. Some proposed solutions could even come back into fashion as more measurements are made, revealing more definitively whether the star has any companions and how they might interact. Using telescopes around the world to analyze the star’s light at all wavelengths and with greater resolution, astronomers are picking out more details of its characteristics.

They’re also monitoring the star over the long term.

Image above: An artistic representation of a burnt- out star. Image Credits: NASA/Ames Research Center/Daniel Rutter.

“To learn more, we needed to catch it in action again. It just comes down to that,” Boyajian said. "We can't rule anything out completely until the evidence warrants it."

In May 2017, and again in June, August and September, the star obliged with new performances of unexplained dimming, and astronomers were ready for it. The dips in brightness were smaller this time, and the four events lasted between five days and two weeks. Scientists are now processing this new data, wondering if it will hold the key to understanding this remarkable star.

"This kind of patiently executed, coordinated monitoring at multiple wavelengths will unlock this mystery eventually," Batalha said.

Until that time, the public and scientists alike can follow the investigation’s progress online with the hashtag #TabbysStar, checking for new clues or new dimming events from the star, and watching as researcher-detectives work hard to crack the case.

Ames manages the Kepler and K2 missions for NASA's Science Mission Directorate. NASA’s Jet Propulsion Laboratory managed Kepler mission development. Ball Aerospace & Technologies Corporation operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. Work on this study was performed in part under contract with the Jet Propulsion Laboratory funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute.

Related links:

Planet Hunters program:

Swift mission:

For more information about the Kepler mission, visit:

Images (mentioned), Text, Credits: NASA/Darryl Waller/Ames Research Center, author: Abby Tabor.


Spacewalkers Wrap Up Robotic Arm Work

ISS - Expedition 53 Mission patch / EVA - Extra Vehicular Activities patch.

October 5, 2017

Expedition 53 Commander Randy Bresnik and Flight Engineer Mark Vande Hei of NASA completed a 6 hour, 55 minute spacewalk at 3 p.m. EDT. The two astronauts replaced one of two Latching End Effectors (LEE) on the station’s robotic arm, Canadarm2.

They also accomplished a couple of get-ahead tasks, including removal of the multi-layer insulation from a spare direct current switching unit. They also prepared a flex hose rotary coupler for future use.

This was the first of three spacewalks planned for October. Bresnik will lead the next two, as well. Vande Hei will join him again Oct. 10 with Flight Engineer Joe Acaba joining him Oct. 18.

Image above: Spacewalkers Mark Vande Hei and Randy Bresnik work on installing a new latching end effector on the tip of the Canadarm2 robotic arm. Image Credit: NASA TV.

The second and third spacewalks will be devoted to lubricating the newly installed end effector and replacing cameras on the left side of the station’s truss and the right side of the station’s U.S. Destiny laboratory.

Today’s spacewalk was the third for Bresnik’s career and the first for Vande Hei. The Oct. 18 spacewalk will mark the third of Acaba’s career.

Related links:

Expedition 53:

Space Station Research and Technology:

International Space Station (ISS):

Image (mentioned), Text, Credits:  NASA/Mark Garcia.

Best regards,

Dune-filled crater in 3D

ESA - Mars Express Mission patch.

5 October 2017

Dune field in a crater, perspective view

Dunes are prominent indicators of prevailing winds, as can be seen on this crater floor on Mars, imaged by ESA’s Mars Express on 16 May.

Depressions such as impact craters can act as traps for sediments that have been blown in from elsewhere, accumulating in various patterns whipped up by strong winds.

Dune field in a crater, plan view

The dune field in this unnamed 48 km-wide impact crater in the southern highlands of Mars includes sickle-shaped dunes known as barchans, and parallel ridges of dunes called transverse dunes.

A smoothly distributed sand sheet stretches between the dunes and the western wall of the crater.

Dune-filled crater in context

Barchans are the most common dune type found on Mars, and are also prevalent in Earth’s deserts. The shallower slope faces the wind, with the steeper, curved slope downwind, the ‘horns’ of the individual dunes pointing in the direction the wind is blowing. In this example, a southeasterly wind at the time of dune formation can be assumed.

Many nearby craters in this region also host dunes, and show a northwest shift of their dune fields relative to the crater centre, arguing for a uniform wind direction from the southeast.

Dune-filled crater topography

To the south of the dune field in the large crater, a single elongated transverse dune extends beyond the main field for several kilometres. Perhaps the underlying topography combined with near-surface winds caused the sediments to pile up here, or over time the smaller barchan dunes joined together.

Dune-filled crater in 3D

This scene is situated south of Tharsis, the largest volcanic province on Mars and home to Olympus Mons. Past volcanic activity in Tharsis produced vast amounts of basalt, fine pyroclastic deposits and ash, which were likely swept across the region to provide a source for the dark dune material observed in these craters today.

Related links:

Mars Express:

Mars Webcam:

Robotic exploration of Mars:

Mars Express overview:

Mars Express in-depth:

ESA Planetary Science archive (PSA):

High Resolution Stereo Camera:

HRSC data viewer:

Behind the lens...

Frequently asked questions:

Images, Text, Credits: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO/NASA MGS MOLA Science Team.

Best regards,

mercredi 4 octobre 2017

Space Station Crew Marks New Era of Research, Preps for Upcoming Spacewalks

ISS - Expedition 53 Mission patch.

Oct. 4, 2017

Expedition 53 marks the first long-term increase in crew size from three to four on the U.S. segment of the International Space station, allowing NASA to maximize time dedicated to research in space. Experiments from a wide array of disciplines are already taking place aboard, including the latest round of the Veggie plant growth payload. 

Highlights of upcoming investigations include demonstrating the benefits of manufacturing fiber optic filaments in a microgravity environment, a new study looking to slow or reverse muscle atrophy in astronauts during spaceflight and exploring the ability of a synthetic bone material capable of adhering bone to metal within minutes to accelerate bone repair.

The increase in crew size enables a high-throughput of science during ever-present operational activities. A trio of spacewalks in October will see astronauts replace one of two Latching End Effectors (LEE) on the station’s robotic arm, Canadarm2, along with several cameras located outside of the station.

International Space Station (ISS)

The crew members also are scheduled to receive Orbital ATK’s next commercial resupply mission in early November, including several tons of research, supplies and vehicle hardware.

The increased crew size is made possible through NASA’s purchase of additional flights from Boeing, with one flight opportunity each in 2017 and 2018 providing more time for research on the International Space Station. The agency also has exercised an option to purchase three additional seats in 2019 to sustain science operations and smooth transition to U.S. commercial crew transportation services.

For more than 16 years, humans have lived and worked continuously aboard the International Space Station, advancing scientific knowledge and demonstrating new technologies, making research breakthroughs not possible on Earth that will enable long-duration human and robotic exploration into deep space. A global endeavor, more than 200 people from 18 countries have visited the unique microgravity laboratory that has hosted more than 2,100 research investigations from researchers in more than 95 countries.

Related links:

Veggie plant growth:

Manufacturing fiber optic filaments:

Slow or reverse muscle atrophy:

Orbital ATK’s next commercial resupply mission:

Commercial Resupply:

Spacewalks in October:

Expedition 53:

Space Station Research and Technology:

International Space Station (ISS):

Image, Text, Credits: NASA/Mark Garcia.

Best regards,

Examining Mars' Moon Phobos in a Different Light

NASA - 2001 Mars Odyssey patch.

Oct. 4, 2017

NASA's longest-lived mission to Mars has gained its first look at the Martian moon Phobos, pursuing a deeper understanding by examining it in infrared wavelengths.

Image above: This image combines two products from the first pointing at the Martian moon Phobos by the THEMIS camera on NASA's Mars Odyssey orbiter, on Sept. 29, 2017. Surface-temperature information from observation in thermal-infrared wavelengths is overlaid on a more detailed image from a visible-light observation. Image Credits: NASA/JPL-Caltech/ASU.

The Thermal Emission Imaging System (THEMIS) camera on NASA's Mars Odyssey orbiter observed Phobos on Sept. 29, 2017. Researchers have combined visible-wavelength and infrared data to produce an image color-coded for surface temperatures of this moon, which has been considered for a potential future human-mission outpost.

Animation above: his series of images was taken in visible-wavelength light as the THEMIS camera on NASA's Mars Odyssey scanned across the Martian moon Phobos on Sept. 29, 2017. The apparent motion is due to progression of the camera's pointing during 18 seconds of observing, not from motion of Phobos. Animation Credits: NASA/JPL-Caltech/ASU.

"Part of the observed face of Phobos was in pre-dawn darkness, part in morning daylight," said THEMIS Deputy Principal Investigator Victoria Hamilton of the Southwest Research Institute, headquartered in San Antonio.

Looking across the image from left to right presents a sequence of times of day on the Martian moon, from before dawn, to sunrise, to increasing amounts of time after dawn. This provides information about how quickly the ground warms, which is related to the texture of the surface. As barefoot beach walks can confirm, sand warms or cools quicker than rocks or pavement.

Image above: This image of Phobos is one product of the first pointing at that Martian moon by the THEMIS camera on NASA's Mars Odyssey orbiter. The Sept. 29, 2017, observation also provided information about temperatures on different areas of Phobos. The oblong moon has an average diameter of about 14 miles. Image Credits: NASA/JPL-Caltech/ASU.

"Including a predawn area in the observation is useful because all the heating from the previous day's sunshine has reached its minimum there," Hamilton said. "As you go from predawn area to morning area you get to watch the heating behavior. If it heats up very quickly, it's likely not very rocky but dusty instead."

Phobos has an oblong shape with an average diameter of about 14 miles (22 kilometers). Cameras on other Mars orbiters have previously taken higher-resolution images of Phobos, but none with the infrared information available from THEMIS. Observations in multiple bands of thermal-infrared wavelengths can yield information about the mineral composition of the surface, as well as the surface texture.

One major question about Phobos and Mars' even smaller moon, Deimos, is whether they are captured asteroids or bits of Mars knocked into the sky by impacts. Compositional information from THEMIS might help pin down their origin.

Image above: Colors in this image of the Martian moon Phobos indicate a range of surface temperatures detected by observing the moon on Sept. 29, 2017, with the Thermal Emission Imaging System (THEMIS) camera on NASA's Mars Odyssey orbiter. Image Credits: NASA/JPL-Caltech/ASU.

Since Odyssey began orbiting the Red Planet in 2001, THEMIS has provided compositional and thermal-properties information from all over Mars, but never before imaged either Martian moon. The Sept. 29 observation was completed to validate that the spacecraft could safely do so, as the start of a possible series of observations of Phobos and Deimos in coming months.

In normal operating mode, Odyssey keeps the THEMIS camera pointed straight down as the spacecraft orbits Mars. In 2014, the spacecraft team at Lockheed Martin Space Systems, Denver; and NASA's Jet Propulsion Laboratory, Pasadena, California; and the THEMIS team at Arizona State University, Tempe, developed procedures to rotate the spacecraft for upward-looking imaging of a comet passing near Mars. The teams have adapted those procedures for imaging the Martian moons.

Artist's view of NASA's Mars Odyssey orbiter. Image Credits: NASA/JPL

"We now have the capability of rotating the spacecraft for THEMIS observations," said Odyssey Project Scientist Jeffrey Plaut of JPL. "There is heightened interest in Phobos because of the possibility that future astronauts could perhaps use it as an outpost."

With the first observation now in hand, plans are advancing for additional opportunities at different illumination phases of Phobos and Deimos.

"We want to get observations under all types of lighting -- fully daylit, a small crescent, during eclipse," Hamilton said. "We hope this is the first of several observations that will help us understand Phobos and Deimos."

Related links:

NASA's Mars Odyssey:

Thermal Emission Imaging System (THEMIS):

Images (mentioned), Animation (mentioned), Text, Credits: NASA/Laurie Cantillo/Dwayne Brown/JPL/Guy Webster/Southwest Research Institute/Deb Schmid/Arizona State University/Karin Valentine/Robert Burnham.

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James Webb Space Telescope to Witness Galactic Infancy

NASA / ESA / CSA - James Webb Space Telescope (JWST) patch.

Oct. 4, 2017

Scientists will use NASA’s James Webb Space Telescope to study sections of the sky previously observed by NASA’s Great Observatories, including the Hubble Space Telescope and the Spitzer Space Telescope, to understand the creation of the universe’s first galaxies and stars.

Image above: The Hubble Ultra Deep Field is a snapshot of about 10,000 galaxies in a tiny patch of sky, taken by NASA’s Hubble Space Telescope. Image Credits: NASA, ESA, S. Beckwith (STScI), the HUDF Team.

After it launches and is fully commissioned, scientists plan to focus Webb telescope on sections of the Hubble Ultra-Deep Field (HUDF) and the Great Observatories Origins Deep Survey (GOODS). These sections of sky are among Webb’s list of targets chosen by guaranteed time observers, scientists who helped develop the telescope and thus get to be among the first to use it to observe the universe. The group of scientists will primarily use Webb’s mid-infrared instrument (MIRI) to examine a section of HUDF, and Webb’s near infrared camera (NIRCam) to image part of GOODS.

“By mixing [the data from] these instruments, we’ll get information about the current star formation rate, but we’ll also get information about the star formation history,” explained Hans Ulrik Nørgaard-Nielsen, an astronomer at the Danish Space Research Institute in Denmark and the principal investigator for the proposed observations.

Pablo Pérez-González, an astrophysics professor at the Complutense University of Madrid in Spain and one of several co-investigators on Nørgaard-Nielsen’s proposed observation, said they will use Webb to observe about 40 percent of the HUDF area with MIRI, in roughly the same location that ground-based telescopes like the Atacama Large Millimeter Array (ALMA) and the Very Large Telescope array (VLT) obtained ultra-deep field data.

The iconic HUDF image shows about 10,000 galaxies in a tiny section of the sky, equivalent to the amount of sky you would see with your naked eye if you looked at it through a soda straw. Many of these galaxies are very faint, more than 1 billion times fainter than what the naked human eye can see, marking them as some of the oldest galaxies within the visible universe.

With its powerful spectrographic instruments, Webb will see much more detail than imaging alone can provide. Spectroscopy measures the spectrum of light, which scientists analyze to determine physical properties of what is being observed, including temperature, mass, and chemical composition. Pérez-González explained this will allow scientists to study how gases transformed into stars in the first galaxies, and to better understand the first phases in the formation of supermassive black holes, including how those black holes affect the formation of their home galaxy. Astronomers believe the center of nearly every galaxy contains a supermassive black hole, and that these black holes are related to galactic formation.

MIRI can observe in the infrared wavelength range of 5 to 28 microns. Pérez-González said they will use the instrument to observe a section of HUDF in 5.6 microns, which Spitzer is capable of, but that Webb will be able to see objects 250 times fainter and with eight times more spatial resolution. In this case, spatial resolution is the ability of an optical telescope, such as Webb, to see the smallest details of an object.

Pérez-González said in the area of HUDF they will observe, Hubble was able to see about 4,000 galaxies. He added that, with Webb, they “will detect around 2,000 to 2,500 galaxies, but in a completely different spectral band, so many galaxies will be quite different from the ones that [Hubble] detected.”

Image above: Artist rending showing light reflecting off of the primary and secondary mirrors of NASA’s James Webb Space Telescope, after it has deployed in space. Image Credits: NASA/Mike McClare.

With NIRCam, the team will observe a piece of the GOODS region near their selected section of HUDF. The entire GOODS survey field includes observations from Hubble, Spitzer, and several other space observatories.

“These NIRCam images will be taken in three bands, and they will be the deepest obtained by any guaranteed time observation team,” explained Pérez-González.

NIRCam can observe in the infrared wavelength range of 0.6 to 5 microns. Pérez-González explained they will use it to observe a section of GOODS in the 1.15 micron band, which Hubble is capable of, but that Webb will be able to see objects 50 times fainter and with two times more spatial resolution. They will also use it to observe the 2.8 and 3.6 micron bands. Spitzer is able to do this as well, but Webb will be able to observe objects nearly 100 times fainter and with eight times greater spatial resolution.

Because the universe is expanding, light from distant objects in the universe is “redshifted,” meaning the light emitted by those objects is visible in the redder wavelengths by the time it reaches us. The objects farthest away from us, those with the highest redshifts, have their light shifted into the near- and mid-infrared part of the electromagnetic spectrum. The Webb telescope is specifically designed to observe the objects in that area of the spectrum, which makes it ideal for looking at the early universe.

“When you build an observatory with unprecedented capabilities, most probably the most interesting results will not be those that you can expect or predict, but those that no one can imagine,” said Pérez-González.

The James Webb Space Telescope, the scientific complement to NASA's Hubble Space Telescope, will be the most powerful space telescope ever built. Webb is an international project led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

MIRI was built by ESA, in partnership with the European Consortium, a group of scientists and engineers from European countries; a team from NASA’s Jet Propulsion Laboratory in Pasadena, California; and scientists from several U.S. institutions. NIRCam was built by Lockheed Martin and the University of Arizona in Tucson.

Related links:

Webb’s mid-infrared instrument (MIRI):

Webb’s near infrared camera (NIRCam):

For more information about Webb telescope, visit: or

For more information about Hubble telescope, visit:

For more information about Spitzer telescope, visit:

Images (mentioned), Text, Credits: NASA/Lynn Jenner/Goddard Space Flight Center, by Eric Villard.


Mysterious Dimming of Tabby's Star May Be Caused by Dust

NASA - Spitzer Space Telescope patch.

Oct. 4, 2017

One of the most mysterious stellar objects may be revealing some of its secrets at last.

Image above: This illustration depicts a hypothetical uneven ring of dust orbiting KIC 8462852, also known as Boyajian’s Star or Tabby's Star. Image Credits: NASA/JPL-Caltech.

Called KIC 8462852, also known as Boyajian’s Star, or Tabby's Star, the object has experienced unusual dips in brightness -- NASA's Kepler space telescope even observed dimming of up to 20 percent over a matter of days. In addition, the star has had much subtler but longer-term enigmatic dimming trends, with one continuing today. None of this behavior is expected for normal stars slightly more massive than the Sun. Speculations have included the idea that the star swallowed a planet that it is unstable, and a more imaginative theory involves a giant contraption or "megastructure" built by an advanced civilization, which could be harvesting energy from the star and causing its brightness to decrease.

A new study using NASA's Spitzer and Swift missions, as well as the Belgian AstroLAB IRIS observatory, suggests that the cause of the dimming over long periods is likely an uneven dust cloud moving around the star. This flies in the face of the "alien megastructure" idea and the other more exotic speculations.

The smoking gun: Researchers found less dimming in the infrared light from the star than in its ultraviolet light. Any object larger than dust particles would dim all wavelengths of light equally when passing in front of Tabby's Star.

Spitzer Space Telescope. Animation Credits: NASA/JPL

"This pretty much rules out the alien megastructure theory, as that could not explain the wavelength-dependent dimming," said Huan Meng, at the University of Arizona, Tucson, who is lead author of the new study published in The Astrophysical Journal. "We suspect, instead, there is a cloud of dust orbiting the star with a roughly 700-day orbital period."

Why Dust is Likely

We experience the uniform dimming of light often in everyday life: If you go to the beach on a bright, sunny day and sit under an umbrella, the umbrella reduces the amount of sunlight hitting your eyes in all wavelengths. But if you wait for the sunset, the sun looks red because the blue and ultraviolet light is scattered away by tiny particles. The new study suggests the objects causing the long-period dimming of Tabby's Star can be no more than a few micrometers in diameter (about one ten-thousandth of an inch).

From January to December 2016, the researchers observed Tabby's Star in ultraviolet using Swift, and in infrared using Spitzer. Supplementing the space telescopes, researchers also observed the star in visible light during the same period using AstroLAB IRIS, a public observatory with a 27-inch-wide (68 centimeter) reflecting telescope located near the Belgian village of Zillebeke.

Based on the strong ultraviolet dip, the researchers determined the blocking particles must be bigger than interstellar dust, small grains that could be located anywhere between Earth and the star. Such small particles could not remain in orbit around the star because pressure from its starlight would drive them farther into space. Dust that orbits a star, called circumstellar dust, is not so small it would fly away, but also not big enough to uniformly block light in all wavelengths. This is currently considered the best explanation, although others are possible.

Collaboration with Amateur Astronomers

Citizen scientists have had an integral part in exploring Tabby's Star since its discovery. Light from this object was first identified as "bizarre" and "interesting" by participants in the Planet Hunters project, which allows anyone to search for planets in the Kepler data. That led to a 2016 study formally introducing the object, which is nicknamed for Tabetha Boyajian, now at Louisiana State University, Baton Rouge, who was the lead author of the original paper and is a co-author of the new study. The recent work on long-period dimming involves amateur astronomers who provide technical and software support to AstroLAB.

Several AstroLAB team members who volunteer at the observatory have no formal astronomy education. Franky Dubois, who operated the telescope during the Tabby's Star observations, was the foreman at a seat belt factory until his retirement. Ludwig Logie, who helps with technical issues on the telescope, is a security coordinator in the construction industry. Steve Rau, who processes observations of star brightness, is a trainer at a Belgian railway company.

Siegfried Vanaverbeke, an AstroLAB volunteer who holds a Ph.D. in physics, became interested in Tabby's Star after reading the 2016 study, and persuaded Dubois, Logie and Rau to use Astrolab to observe it.

"I said to my colleagues: 'This would be an interesting object to follow,'" Vanaverbeke  recalled. "We decided to join in."

University of Arizona astronomer George Rieke, a co-author on the new study, contacted the AstroLAB group when he saw their data on Tabby's Star posted in a public astronomy archive. The U.S. and Belgium groups teamed up to combine and analyze their results.

Future Exploration

While study authors have a good idea why Tabby's Star dims on a long-term basis, they did not address the shorter-term dimming events that happened in three-day spurts in 2017. They also did not confront the mystery of the major 20-percent dips in brightness that Kepler observed while studying the Cygnus field of its primary mission. Previous research with Spitzer and NASA's Wide-field Infrared Survey Explorer suggested a swarm of comets may be to blame for the short-period dimming. Comets are also one of the most common sources of dust that orbits stars, and so could also be related to the long-period dimming studied by Meng and colleagues.

Now that Kepler is exploring other patches of sky in its current mission, called K2, it can no longer follow up on Tabby's Star, but future telescopes may help unveil more secrets of this mysterious object.

"Tabby's Star could have something like a solar activity cycle. This is something that needs further investigation and will continue to interest scientists for many years to come," Vanaverbeke said.

NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the Swift mission in collaboration with Pennsylvania State University in University Park, the Los Alamos National Laboratory in New Mexico, and Orbital Sciences Corp. in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, with additional collaborators in Germany and Japan.

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena, California. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit: and

The Astrophysical Journal:;jsessionid=F8E69D428486198F83420B1D05CB682E.ip-10-40-2-120

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


Sputnik – 60 years of the space age

CCCP - Baikonur Cosmodrome Sputnik-1 patch.

4 October 2017

Sputnik 1, the first artificial satellite

Sixty years ago, the first ‘beep-beep’ signal from Sputnik was heard from the heavens on the night of 4 October 1957, marking the beginning of a new era for humankind.

The goal of launching an artificial satellite to orbit Earth had been one for the international scientific community for some time, and had helped inspire the International Geophysical Year 1957–58, but the successful launch by the Soviet Union came as a shock, and the reception of the signal worldwide was incontrovertible proof of their success.

Sputnik launch

The launch of Sputnik-1, as it was officially called, signalled the start of the ‘Space Age’, and fuelled the space race between the Soviet Union and the United States that was to result in more than a decade of unprecedented achievement. Initial reactions to Sputnik were guarded – the ability to launch an artificial satellite could also indicate the development of new weapons.

But the arrival of Space Age also inspired science and engineering to take new peaceful steps. Just months after the launch of Sputnik, Frank McClure, of the Johns Hopkins Applied Physics Laboratory, described the potential of satellites for a space-based navigation system. Visions of sending robots and humans into space were becoming reality.

Satellites and spaceprobes have dramatically changed our way of living, they have turned the world into a global village where an unprecedented wealth of information is at hand anywhere, at any time. The world has shrunk, and our perception of our planet has changed too. Thanks to remote sensing and Earth observation, we can now take the pulse of our environment and respond based on an increasing knowledge of the way our world is evolving.

Technician working on Sputnik-1, 1957

We have explored many worlds in the Solar System and our space-based instruments have been able to open large windows into previously unknown realms of the Universe. We have revealed thousands of galaxies in areas of the sky that, until recently, looked like empty blackness.

Women and men have ventured out of their planetary cradle and have succeeded in their first explorations of another world. They have settled in space and started to work there, first in competition, and then in global cooperation, in a spirit of peace and for the benefit of humankind. On the ground, engineers, scientists, technicians, politicians and visionaries have all worked together to make dreams come true, changing our lives for ever, and for the better.

Sputnik-1 - Celebrating 60 years of the Space Age

Europe has taken its own part in this great adventure. From the theories that spawned great achievements to the science and technology that completed them, Europe has shared in global progress. From rocket design to geostationary orbits, European scientists have been involved in many of the successes of the past six decades.

The surprise and anxiety of that night 60 years ago have been replaced with wonder and amazement at the achievements of the Space Age. As humans look to travel farther and experiment further, the decades ahead appear full of adventure.

Related article:

ROSCOSMOS website commemorative article (in Russian):

Images, Video, Text, Credits: ESA/RKK Energiya/Solaris/

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