samedi 20 janvier 2018

ULA Successfully Launches SBIRS GEO Flight 4 Mission for the USAF

ULA - SBIRS GEO Flight 4 Mission poster.

Jan. 20, 2018

Atlas V SBIRS GEO Flight 4 Mission Overview

Image above: An Atlas V rocket carrying the SBIRS GEO Flight 4 mission for the U.S. Air Force lifts off from Space Launch Complex-41. Image Credit: ULA.

A United Launch Alliance (ULA) Atlas V rocket carrying the Space Based Infrared System (SBIRS) GEO Flight 4 mission lifted off from Space Launch Complex-41 on Jan. 19 at 7:48 p.m. EST. SBIRS is considered one of the nation’s highest priority space programs, and is designed to provide global, persistent, infrared surveillance capabilities to meet 21st century demands.

“Meeting the challenge of launching two critical national security missions from opposite coasts within a week, the entire ULA team once again demonstrated its unwavering dedication to 100% mission success,” said Laura Maginnis, ULA vice president of Government Satellite Launch. “Thank you to our U.S. Air Force and industry teammates for their outstanding partnership in successfully delivering SBIRS to orbit today.”

Atlas V SBIRS GEO Flight 4 Launch Highlights

This mission was launched aboard an Atlas V Evolved Expendable Launch Vehicle (EELV) 411 configuration vehicle, which includes a 4-meter Payload Fairing (PLF). The Atlas booster for this mission was powered by the RD AMROSS RD-180 engine. Aerojet Rocketdyne provided the AJ-60A solid rocket booster (SRB) and RL10C-1 engine for the Centaur upper stage.

This is the 75th launch of the Atlas V rocket, ULA’s 2nd launch in 2018 and the 125th successful launch since the company was formed in December 2006.

SBIRS GEO Flight 4 satellite. Image Credit: ULA

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

ULA's next launch is the GOES-S mission for NASA and NOAA on an Atlas V rocket. The launch is scheduled for March 1 from Space Launch Complex-41 at Cape Canaveral Air Force Station, Florida.

With more than a century of combined heritage, United Launch Alliance is the nation’s most experienced and reliable launch service provider. ULA has successfully delivered more than 120 satellites to orbit that aid meteorologists in tracking severe weather, unlock the mysteries of our solar system, provide critical capabilities for troops in the field and enable personal device-based GPS navigation.

For more information on ULA, visit the ULA website at

Images (mentioned), Video, Text, Credit: United Launch Alliance (ULA).


vendredi 19 janvier 2018

Space Station Orbits Earth for 7000th Day

ISS - Expedition 54 Mission patch.

Jan. 19, 2018

The International Space Station has been orbiting Earth for 7,000 days as of today Friday, Jan. 19, 2018. The first module, the Russian Zarya cargo module, launched to space in November of 1998. The first crew arrived at the young three-module orbital laboratory in November of 2000.

54 crews and 205 spacewalks later, the current six-member Expedition 54 crew is gearing up for a pair of spacewalks on Jan. 23 and 29. NASA astronaut Mark Vande Hei will lead both spacewalks with Flight Engineer Scott Tingle joining him on the first spacewalk. Japanese astronaut Norishige Kanai will join Vande Hei for the second spacewalk.

Image above: Clockwise from top left: The first station module, Zarya from Russia, is pictured December 1998 from Space Shuttle Endeavour; the first station crew, Expedition 1, was onboard the station in February of 2001; a growing station was pictured in June of 2007; the station in its near final configuration in February 2010.

All three astronauts were joined today by Flight Engineer Acaba for a spacewalk procedures review with specialists on the ground. The spacewalking trio will be swapping and stowing robotics parts to maintain the upkeep of the Canadarm2 robotic arm. Both spacewalks will start each day at 7:10 a.m. EST with live NASA Television coverage beginning at 5:30 a.m.

The two cosmonauts aboard the space station, Commander Alexander Misurkin and Flight Engineer Anton Shkaplerov, conducted regularly scheduled eye checks today. The veteran orbital residents worked with doctors on the ground using a fundoscope to view the interior of the eye. Crew members aboard the station participate in regular eye exams to understand how living in space affects vision.

Related links:

Expedition 54:

Space Station Research and Technology:

International Space Station (ISS):

Image, Text, Credits: NASA/Mark Garcia.

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Hubble’s Cartwheel

NASA - Hubble Space Telescope patch.

Jan. 19, 2018

This is an image of the Cartwheel Galaxy taken with the NASA/ESA (European Space Agency) Hubble Space Telescope.

The object was first spotted on wide-field images from the U.K. Schmidt telescope and then studied in detail using the Anglo-Australian Telescope.

Lying about 500 million light-years away in the constellation of Sculptor, the cartwheel shape of this galaxy is the result of a violent galactic collision. A smaller galaxy has passed right through a large disk galaxy and produced shock waves that swept up gas and dust — much like the ripples produced when a stone is dropped into a lake — and sparked regions of intense star formation (appearing blue). The outermost ring of the galaxy, which is 1.5 times the size of our Milky Way, marks the shock wave’s leading edge. This object is one of the most dramatic examples of the small class of ring galaxies.

This image is based on earlier Hubble data of the Cartwheel Galaxy that was reprocessed in 2010, bringing out more detail in the image than seen before.

For more information about Hubble, visit:

Image credits: ESA/Hubble & NASA/Text credits: ESA/NASA/Rob Garner.


Asteroid 2002 AJ129 to Fly Safely Past Earth February 4

Asteroid Watch logo.

Jan. 19, 2018

Asteroid 2002 AJ129 will make a close approach to Earth on Feb. 4, 2018 at 1:30 p.m. PST (4:30 p.m. EST / 21:30 UTC). At the time of closest approach, the asteroid will be no closer than 10 times the distance between Earth and the Moon (about 2.6 million miles, or 4.2 million kilometers).

Trajectory of Asteroid 2002 AJ129

Video above: Asteroid 2002 AJ129 will make a close approach to Earth on Feb. 4, 2018, at 1:30 p.m. PST (4:30 p.m. EST). At the time of closest approach, the asteroid will be at a distance of 2.6 million miles, or 4.2 million kilometers -- about 10 times the distance between Earth and the moon.

2002 AJ129 is an intermediate-sized near-Earth asteroid, somewhere between 0.3 miles (0.5 kilometers) and 0.75 miles (1.2 kilometers) across. It was discovered on Jan. 15, 2002, by the former NASA-sponsored Near Earth Asteroid Tracking project at the Maui Space Surveillance Site on Haleakala, Hawaii. The asteroid’s velocity at the time of closest approach, 76,000 mph (34 kilometers per second), is higher than the majority of near-Earth objects during an Earth flyby. The high flyby velocity is a result of the asteroid’s orbit, which approaches very close to the Sun -- 11 million miles (18 million kilometers). Although asteroid 2002 AJ129 is categorized as a Potentially Hazardous Asteroid (PHA), it does not pose an actual threat of colliding with our planet for the foreseeable future.

Near-Earth asteroid. Image Credit: ESA

“We have been tracking this asteroid for over 14 years and know its orbit very accurately,” said Paul Chodas, manager of NASA’s Center for Near-Earth Object Studies at the Jet Propulsion Laboratory, Pasadena, California.  “Our calculations indicate that asteroid 2002 AJ129 has no chance — zero — of colliding with Earth on Feb. 4 or any time over the next 100 years.”

JPL hosts the Center for Near-Earth Object Studies for NASA's Near-Earth Object Observations Program, an element of the Planetary Defense Coordination Office within the agency's Science Mission Directorate.

More information about asteroids and near-Earth objects can be found at:


For more information about NASA's Planetary Defense Coordination Office, visit:

For asteroid and comet news and updates, follow AsteroidWatch on Twitter:

Video, Image (mentioned), Text, Credits: NASA/Tony Greicius/JPL/DC Agle.


jeudi 18 janvier 2018

NASA Team Studies Middle-aged Sun by Tracking Motion of Mercury

NASA - MESSENGER Mission patch.

Jan. 18, 2018

Mercury. Image Credits: NASA/MESSENGER/JHUAPL/CW

Like the waistband of a couch potato in midlife, the orbits of planets in our solar system are expanding. It happens because the Sun’s gravitational grip gradually weakens as our star ages and loses mass. Now, a team of NASA and MIT scientists has indirectly measured this mass loss and other solar parameters by looking at changes in Mercury’s orbit.

The new values improve upon earlier predictions by reducing the amount of uncertainty. That’s especially important for the rate of solar mass loss, because it’s related to the stability of G, the gravitational constant. Although G is considered a fixed number, whether it’s really constant is still a fundamental question in physics.

“Mercury is the perfect test object for these experiments because it is so sensitive to the gravitational effect and activity of the Sun,” said Antonio Genova, the lead author of the study published in Nature Communications and a Massachusetts Institute of Technology researcher working at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The study began by improving Mercury’s charted ephemeris — the road map of the planet’s position in our sky over time. For that, the team drew on radio tracking data that monitored the location of NASA’s MESSENGER spacecraft while the mission was active. Short for Mercury Surface, Space Environment, Geochemistry, and Ranging, the robotic spacecraft made three flybys of Mercury in 2008 and 2009 and orbited the planet from March 2011 through April 2015. The scientists worked backward, analyzing subtle changes in Mercury’s motion as a way of learning about the Sun and how its physical parameters influence the planet’s orbit.

Image above: NASA and MIT scientists analyzed subtle changes in Mercury’s motion to learn about the Sun and how its dynamics influence the planet’s orbit. The position of Mercury over time was determined from radio tracking data obtained while NASA’s MESSENGER mission was active. Image Credits: NASA's Goddard Space Flight Center.

For centuries, scientists have studied Mercury’s motion, paying particular attention to its perihelion, or the closest point to the Sun during its orbit. Observations long ago revealed that the perihelion shifts over time, called precession. Although the gravitational tugs of other planets account for most of Mercury’s precession, they don’t account for all of it.

The second-largest contribution comes from the warping of space-time around the Sun because of the star’s own gravity, which is covered by Einstein’s theory of general relativity. The success of general relativity in explaining most of Mercury’s remaining precession helped persuade scientists that Einstein’s theory was right.

Other, much smaller contributions to Mercury’s precession, are attributed to the Sun’s interior structure and dynamics. One of those is the Sun’s oblateness, a measure of how much it bulges at the middle — its own version of a “spare tire” around the waist — rather than being a perfect sphere. The researchers obtained an improved estimate of oblateness that is consistent with other types of studies.

The researchers were able to separate some of the solar parameters from the relativistic effects, something not accomplished by earlier studies that relied on ephemeris data. The team developed a novel technique that simultaneously estimated and integrated the orbits of both MESSENGER and Mercury, leading to a comprehensive solution that includes quantities related to the evolution of Sun’s interior and to relativistic effects.

Image above: Mercury’s proximity to the Sun and small size make it exquisitely sensitive to the dynamics of the Sun and its gravitational pull. Image Credits: NASA/SDO.

“We’re addressing long-standing and very important questions both in fundamental physics and solar science by using a planetary-science approach,” said Goddard geophysicist Erwan Mazarico. “By coming at these problems from a different perspective, we can gain more confidence in the numbers, and we can learn more about the interplay between the Sun and the planets.”

The team’s new estimate of the rate of solar mass loss represents one of the first times this value has been constrained based on observations rather than theoretical calculations. From the theoretical work, scientists previously predicted a loss of one-tenth of a percent of the Sun’s mass over 10 billion years; that’s enough to reduce the star’s gravitational pull and allow the orbits of the planets to spread by about half an inch, or 1.5 centimeters, per year per AU (an AU, or astronomical unit, is the distance between Earth and the Sun: about 93 million miles).

The new value is slightly lower than earlier predictions but has less uncertainty. That made it possible for the team to improve the stability of G by a factor of 10, compared to values derived from studies of the motion of the Moon.

“The study demonstrates how making measurements of planetary orbit changes throughout the solar system opens the possibility of future discoveries about the nature of the Sun and planets, and indeed, about the basic workings of the universe,” said co-author Maria Zuber, vice president for research at MIT.

Related links:

Nature Communications:

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging):

Images (mentioned), Text, Credits: NASA/Rob Garner/Goddard Space Flight Center, By Elizabeth Zubritsky.

Best regards,

Jupiter’s Swirling South Pole

NASA - JUNO Mission logo.

Jan. 18, 2018

This image of Jupiter’s swirling south polar region was captured by NASA’s Juno spacecraft as it neared completion of its tenth close flyby of the gas giant planet.

The “empty” space above and below Jupiter in this color-enhanced image can trick the mind, causing the viewer to perceive our solar system’s largest planet as less colossal than it is. In reality, Jupiter is wide enough to fit 11 Earths across its clouded disk.

The spacecraft captured this image on Dec. 16, 2017, at 11:07 PST (2:07 p.m. EST) when the spacecraft was about 64,899 miles (104,446 kilometers) from the tops of the clouds of the planet at a latitude of 83.9 degrees south — almost directly over Jupiter’s south pole.

The spatial scale in this image is 43.6 miles/pixel (70.2 kilometers/pixel).

Citizen scientist Gerald Eichstädt processed this image using data from the JunoCam imager.

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, Text, Credits: NASA/Tony Greicius/JPL-Caltech/SwRI/MSSS/Gerald Eichstädt.


North, east, south, west: The many faces of Abell 1758

ESA - Hubble Space Telescope logo.

18 January 2018

Northern part of Abell 1758

Resembling a swarm of flickering fireflies, this beautiful galaxy cluster glows intensely in the dark cosmos, accompanied by the myriad bright lights of foreground stars and swirling spiral galaxies. A1758N is a sub-cluster of Abell 1758, a massive cluster containing hundreds of galaxies. Although it may appear serene in this NASA/ESA Hubble Space Telescope image, the sub-cluster actually comprises two even smaller structures currently in the turbulent process of merging.

Although often overshadowed by its more famous cousins — including the Fornax Cluster and Pandora’s Cluster — Abell 1758 contains more than its fair share of intrigue. The cluster was first identified in 1958, and initially logged as a single massive object. However, some 40 years later the cluster was observed again by the ROSAT satellite X-ray telescope, and astronomers spotted something peculiar: the cluster was not a single concentration of galaxies, but two!

Wide-field view of Abell 1758 (ground-based view)

Abell 1758 has since been observed many more times by various observatories — Hubble, NASA’s Chandra X-ray Observatory, ESA’s XMM-Newton, and more — and is now known to have both a double structure and a complex history. It contains two massive sub-clusters sitting some 2.4 million light-years apart. These components, known as A1758N (North) and A1758S (South), are bound together by gravity but without showing signs of interacting.

In this Hubble image only the northern structure of the cluster, A1758N, is visible. A1758N is further split into two sub-structures, known as East (A1758NE) and West (A1758NW). There appear to be disturbances within each of of the two sub-clusters of A1758A — strong evidence that they are the result of smaller clusters colliding and merging.

Zooming into the galaxy cluster A1758N

Studies have also revealed a radio halo and two radio relics within Abell 1758. Through Hubble’s eyes these radio structures are invisible, but radio telescopes reveal an oddly-shaped halo of emission around the cluster. Radio halos are vast sources of diffuse radio emission usually found around the centres of galaxy clusters. They are thought to form when clusters collide and accelerate fast-moving particles to even higher speeds, implying that clusters with radio halos are still forming and merging.

Collisions such as the one A1758N is undergoing are the most energetic events in the Universe apart from the Big Bang itself. Understanding how clusters merge helps astronomers to understand how structures grow and evolve in the Universe. It also helps them to study dark matter, the intracluster medium and galaxies, and to explore how these three components interact — particularly during mergers.

Panning across the galaxy cluster A1725N

This image was taken by Hubble’s Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3) as part of an observing programme called RELICS. The programme is imaging 41 massive galaxy clusters, using them as cosmic lenses to search for bright distant galaxies. These will then be studied in more detail using both current telescopes and the future NASA/ESA/CSA James Webb Space Telescope.
More information

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.


Images of Hubble:

Hubble Space Telescope:

Images, Text, Credits: NASA, ESA/Nicole Shearer/Digitized Sky Survey 2/Videos: Akira Fujii/David Malin Images, DSS, ESA/Hubble/Music: Johan B. Monell.

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Crater Neukum named after Mars Express founder

ESA - Mars Express Mission patch.

18 January 2018

A fascinating martian crater has been chosen to honour the German physicist and planetary scientist, Gerhard Neukum, one of the founders of ESA’s Mars Express mission.

 Neukum Crater

The International Astronomical Union named the 102 km-wide crater in the Noachis Terra region “Neukum” in September last year after the camera’s leader, who died in 2014. Professor Neukum inspired and led the development of the high-resolution stereo camera on Mars Express, which helped to establish the regional geology and topography of Mars.

Observations by the camera in December 2005 and May 2007 were used to create the image mosaic of Neukum Crater presented here.

Neukum Crater in context

Neukum Crater sits in the Noachis Terra region in the densely cratered southern highlands of Mars, some 800 km to the west of the planet’s largest impact basin, Hellas. Noachis Terra is one of the oldest known regions on the Red Planet, dating back at least 3.9 billion years – the earliest martian era, the Noachian epoch, is named after it.

It is representative of the ancient surface of Mars, which is characteristically peppered with craters that have been preserved for billions of years, although many have degraded over time.

Neukum Crater perspective view

Many impact craters in Noachis Terra host dune fields, and in this scene, Neukum Crater displays a particularly interesting pattern with dunes covering an area of about 12 x 17 km in the southeast corner of the crater.

The individual dunes stretch out in a north–south direction, with the dominant slipface towards the west, pointing to a prevailing wind coming from the east. In addition, dark sands have been blown to the west and north of the dunes, indicative of the strong easterly – and some southerly – winds.

Neukum Crater topography

The formation of light-toned deposits west of the dune field is unclear: they might be boulders or erosional remnants from the rocky crater interior.

The crater’s shallow interior has likely been infilled by sediments over its history. It is also marked with two irregular depressions. Perhaps they are a sign of a weaker material that has since eroded away, leaving behind some islands of more resistant material.

Neukum Crater in 3D

Over time the interior of the crater rim has undergone varying degrees of collapse, with landslides visible in the perspective view. Many smaller craters have also overprinted the rim and pockmarked the interior since Neukum Crater was formed, highlighting its long history.

Related links:

Professor Neukum:

Mars Express:

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.

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mercredi 17 janvier 2018

‘First Light’ Images from CERES FM6 Earth-observing Instrument

NOAA & NASA - JPSS-1 Mission patch.

Jan. 17, 2018

It’s working!

The covers on the Clouds and the Earth's Radiant Energy System Flight Model 6 (CERES FM6) opened Jan. 5, allowing it to scan Earth for the first time.

The instrument was one of five that launched Nov. 18, 2017, on the National Oceanic and Atmospheric Adminstration's (NOAA) Joint Polar Satellite System 1 (JPSS-1). After reaching polar orbit Nov. 18, the satellite became known as NOAA-20.

Cover-opening activities began around 8:30 p.m. ET Jan. 4 and were completed at approximately 1:45 a.m. Jan. 5. CERES FM6 began scanning Earth at approximately 1:25 p.m. Jan. 5. On Jan. 10, scientists used those scans to produce the "first light" images.

Image above: In this shortwave image from CERES FM6, the white and green shades represent thick cloud cover reflecting incoming solar energy back to space. Compare that with the darker blue regions, which have no cloud cover, to get a sense for just how much clouds can affect the balance of incoming and outgoing energy on Earth. Image Credit: NASA.

Built by Northrop Grumman, funded by NOAA and managed by NASA's Langley Research Center in Hampton, Virginia, in coordination with the JPSS program, CERES FM6 is the last in a series of instruments going back to the late 1990s that measure the solar energy reflected by Earth, the heat the planet emits, and the role of clouds in that process.

“CERES FM6 is the seventh and final copy since we first launched the first CERES instrument in 1997. It is the most accurate broadband radiometer that NASA/NOAA have flown as a result of a more rigorous prelaunch calibration campaign than previous instruments," said CERES Project Scientist Kory Priestley. "We were able to take knowledge from on-orbit operations and apply it to this flight model. We’ve done a better job of building and characterizing the instrument, and with hope that will bear fruit as the mission is flown.

“The robustness of the CERES instruments already on-orbit, having exceeded their design lifetimes by a factor of two to three, is testament to the work of the dedicated team of engineers at Northrop Grumman,” Priestley said. “The scientific discoveries the community will make by utilizing these datasets will benefit humanity for decades to come.”

Image above: In this longwave image from CERES FM6, heat energy radiated from Earth is represented by shades of yellow, red, blue and white. Bright yellow regions are the hottest and emit the most energy out to space. Dark blue and bright white regions, which represent clouds, are much colder and emit the least energy. Image Credit: NASA.

Five other CERES instruments are flying on three other satellites. Their data helps scientists validate models that calculate the effect of clouds on planetary heating and cooling. The same data can also be helpful for improving near-term, seasonal forecasts influenced by weather events such as El Niño and La Niña. El Niño and La Niña are climatic fluctuations in the temperature of the tropical Pacific Ocean that can influence weather globally.

"The successful launch of CERES FM6 and acquisition of initial data is fantastic news," said David Considine, program manager for NASA's Modeling, Analysis and Prediction program. "Its data will help us to understand the critical role that clouds play in the Earth system, and shows the value to the Nation of the NASA and NOAA collaboration leading to this achievement."

The CERES data record extends back to 1997. Prior to CERES, the Earth Radiation Budget Experiment (ERBE) collected similar data beginning in 1984. The two NASA programs demonstrate NASA’s long-term involvement in measuring Earth's energy balance going back more than 30 years.

Joint Polar Satellite System 1 (JPSS-1). Image Credit: NOAA

“Northrop Grumman is proud to be a collaborative partner with NASA and NOAA on this successful CERES mission. Between the seven CERES instruments and their ERBE predecessors, we have had a relationship in Earth radiation budget measurements that now spans over three decades," said Northrop Grumman CERES Program Manager Sean Kelly. "The CERES instruments continue to reliably provide the climate data record necessary for monitoring, processing and analyzing critical data for the Earth science community. CERES is one of the most highly calibrated, highly reliable instruments on-orbit today."

Related links:

Joint Polar Satellite System 1 (JPSS-1):


Images 8mentioned), Text, Credits: NASA Langley Research Center/Joe Atkinson.


Success of Epsilon-3 Launch with ASNARO-2 Aboard

JAXA - Epsilon 03 Mission patch.

Jan. 18, 2018 (JST)

Epsilon-3 Launch with ASNARO-2 Aboard

At 6:06:11 a.m. (Japan Standard Time) January 18, 2017, JAXA launched Epsilon-3, the third Epsilon launch vehicle which encapsulates NEC Small radar satellite "ASNARO-2", from the JAXA Uchinoura Space Center.

Video above: The live launch report for the third Epsilon Launch Vehicle with the NEC small radar satellite "ASNARO-2". Video Credit: JAXA.

The launch occurred on time. The launch and flight of Epsilon-3 took place normally. Approximately 52 minutes 35 seconds into the flight, the separation of ASNARO-2 proceeded, with confirmation as successful.

ASNARO-2 satellite

The project is the second for the ASNARO program, which stands for Advanced Satellite with New System ARchitecture for Observation.

For more information about Japan Aerospace Exploration Agency (JAXA), visit:

Images, Video, Text, Credits: Japan Aerospace Exploration Agency (JAXA).


Cassini Finds Saturn Moon Has 'Sea Level' Like Earth

NASA - Cassini International logo.

Jan. 17, 2018

Saturn’s moon Titan may be nearly a billion miles away from Earth, but a recently published paper based on data from NASA’s Cassini spacecraft reveals a new way this distant world and our own are eerily similar. Just as the surface of oceans on Earth lies at an average elevation that we call “sea level,” Titan’s seas also lie at an average elevation.

Image above: Ligeia Mare, shown in here in data obtained by NASA's Cassini spacecraft, is the second largest known body of liquid on Saturn's moon Titan. It is filled with liquid hydrocarbons, such as ethane and methane, and is one of the many seas and lakes that bejewel Titan's north polar region. Cassini has yet to observe waves on Ligeia Mare and will look again during its next encounter on May 23, 2013. Image Credits: NASA/JPL-Caltech/ASI/Cornell.

This is the latest finding that shows remarkable similarities between Earth and Titan, the only other world we know of in our solar system that has stable liquid on its surface. The twist at Titan is that its lakes and seas are filled with hydrocarbons rather than liquid water, and water ice overlain by a layer of solid organic material serves as the bedrock surrounding these lakes and seas.

The new paper, led by Alex Hayes at Cornell University in Ithaca, New York, and published in the journal Geophysical Research Letters, finds that Titan’s seas follow a constant elevation relative to Titan’s gravitational pull -- just like Earth’s oceans. Smaller lakes on Titan, it turns out, appear at elevations several hundred feet, or meters, higher than Titan’s sea level. Lakes at high elevation are commonly found on Earth. The highest lake navigable by large ships, Lake Titicaca, is over 12,000 feet [3,700 meters] above sea level.

Image above: Titan is the only world in our solar system other than Earth that has stable liquid on its surface. The liquid in Titan's lakes and seas is mostly methane and ethane. Image Credits: NASA/JPL-Caltech/ASI/USGS.

The new study suggests that elevation is important because Titan’s liquid bodies appear to be connected under the surface in something akin to an aquifer system at Earth. Hydrocarbons appear to be flowing underneath Titan’s surface similar to the way water flows through underground porous rock or gravel on Earth, so that nearby lakes communicate with each other and share a common liquid level.

The paper was based on data obtained by Cassini’s radar instrument until just months before the spacecraft burned up in the Saturn atmosphere last year. It also used a new topographical map published in the same issue of Geophysical Research Letters.

For more details on the two papers, visit:

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

More information about Cassini:

Images (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Jia-Rui Cook.

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Even in the Desert


Jan. 17, 2018

For the second time in three years, snow has accumulated in the desert near the northern Algerian town of Aïn Séfra. Sometimes called the “gateway to the desert,” the town of 35,000 people sits between the Sahara and the Atlas Mountains. On January 8, Landsat 8 captured data for these natural-color images of the snow in the Sahara. The Landsat 8 image was draped over a global digital elevation model, built from data acquired by NASA’s Shuttle Radar Topography Mission.

According to news and social media accounts, anywhere from 10 to 30 centimeters (4 to 12 inches) of snow accumulated on January 8, 2018, on some higher desert elevations (1000 meters or more above sea level). Social media photos showed citizens sliding down snow-covered sand dunes. Warming temperatures melted much of it within a day.

Snow in the Sahara and other parts of North Africa is infrequent, but not unprecedented. Measurable snow fell near Aïn Séfra in December 2016. Substantial snow also blanketed the Atlas Mountains in Morocco in February 2012 and January 2005.

Landsat 8:

NASA’s Shuttle Radar Topography Mission:

Image, Text, Credits: NASA Earth Observatory image by Joshua Stevens, using Landsat data from the U.S. Geological Survey and topographic data from the Shuttle Radar Topography Mission/Yvette Smith.


Odd Behaviour of Star Reveals Lonely Black Hole Hiding in Giant Star Cluster

ESO - European Southern Observatory logo.

17 January 2018

Artist’s impression of the black hole binary system in NGC 3201

Astronomers using ESO’s MUSE instrument on the Very Large Telescope in Chile have discovered a star in the cluster NGC 3201 that is behaving very strangely. It appears to be orbiting an invisible black hole with about four times the mass of the Sun — the first such inactive stellar-mass black hole found in a globular cluster and the first found by directly detecting its gravitational pull. This important discovery impacts on our understanding of the formation of these star clusters, black holes, and the origins of gravitational wave events.

Hubble image of the globular star cluster NGC 3201 (annotated)

Globular star clusters are huge spheres of tens of thousands of stars that orbit most galaxies. They are among the oldest known stellar systems in the Universe and date back to near the beginning of galaxy growth and evolution. More than 150 are currently known to belong to the Milky Way.

Wide-field image of the sky around the globular star cluster NGC 3201

One particular cluster, called NGC 3201 and situated in the southern constellation of Vela (The Sails), has now been studied using the MUSE instrument on ESO’s Very Large Telescope in Chile. An international team of astronomers has found that one of the stars [1] in NGC 3201 is behaving very oddly — it is being flung backwards and forwards at speeds of several hundred thousand kilometres per hour, with the pattern repeating every 167 days [2].

The globular cluster NGC 3201

Lead author Benjamin Giesers (Georg-August-Universität Göttingen, Germany) was intrigued by the star’s behaviour: “It was orbiting something that was completely invisible, which had a mass more than four times the Sun — this could only be a black hole! The first one found in a globular cluster by directly observing its gravitational pull.”

Hubble image of the globular star cluster NGC 3201 (unannotated)

The relationship between black holes and globular clusters is an important but mysterious one. Because of their large masses and great ages, these clusters are thought to have produced a large number of stellar-mass black holes — created as massive stars within them exploded and collapsed over the long lifetime of the cluster [3][4].

The globular cluster NGC 3201 in the constellation of Vela (The Sails)

ESO’s MUSE instrument provides astronomers with a unique ability to measure the motions of thousands of far away stars at the same time. With this new finding, the team have for the first time been able to detect an inactive black hole at the heart of a globular cluster — one that is not currently swallowing matter and is not surrounded by a glowing disc of gas. They could estimate the black hole’s mass through the movements of a star caught up in its enormous gravitational pull [5].

Zooming in on the globular star cluster NGC 3201

From its observed properties the star was determined to be about 0.8 times the mass of our Sun, and the mass of its mysterious counterpart was calculated at around 4.36 times the Sun’s mass — almost certainly a black hole [6].

Artist’s impression video of the black hole binary system in NGC 3201

Recent detections of radio and X-ray sources in globular clusters, as well as the 2016 detection of gravitational-wave signals produced by the merging of two stellar-mass black holes, suggest that these relatively small black holes may be more common in globular clusters than previously thought.

Artist’s impression video of the black hole binary system in NGC 3201

Giesers concludes: “Until recently, it was assumed that almost all black holes would disappear from globular clusters after a short time and that systems like this should not even exist! But clearly this is not the case — our discovery is the first direct detection of the gravitational effects of a stellar-mass black hole in a globular cluster. This finding helps in understanding the formation of globular clusters and the evolution of black holes and binary systems — vital in the context of understanding gravitational wave sources.”

Artist’s impression video of the black hole binary system in NGC 3201


[1] The star found is a main sequence turn-off star, meaning it is at the end of the main sequence phase of its life. Having exhausted its primary hydrogen fuel supply it is now on the way to becoming a red giant.

[2] A large survey of 25 globular clusters around the Milky Way is currently being conducted using ESO’s MUSE instrument with the support of the MUSE consortium. It will provide astronomers with the spectra of 600 to 27 000 stars in each cluster. The study includes analysis of the “radial velocity” of individual stars — the speed at which they move away from and toward the Earth, along the line of sight of the observer. With radial velocity measurements the orbits of stars can be determined, as well as the properties of any massive object they may be orbiting.

[3] In the absence of continuous star formation, as is the case for globular clusters, stellar-mass black holes soon become the most massive objects present. Generally, stellar-mass black holes in globular clusters are about four times as massive as the surrounding low-mass stars. Recent theories have concluded that black holes form a dense nucleus within the cluster, which then becomes detached from the rest of the globular material. Movements at the centre of the cluster are then thought to eject the majority of black holes, meaning only a few would survive after a billion years.

[4] Stellar-mass black holes — or collapsars — are formed when massive stars die, collapsing under their own gravity and exploding as powerful hypernovae. Left behind is a black hole with most of the mass of the former star, which can range from a few times the mass of our Sun to several tens of times as massive.

[5] As no light is able to escape black holes because of their tremendous gravity, the primary method of detecting them is through observations of radio or X-ray emissions coming from hot material around them. But when a black hole is not interacting with hot matter and so not accumulating mass or emitting radiation, as in this case, the black hole is “inactive” and invisible, so another method of detection is required.

[6] Because the non-luminous object in this binary system cannot be directly observed there are alternative, although much less persuasive, explanations for what it could be. It is perhaps a triple star system made up of two tightly bound neutron stars, with the observed star orbiting around them. This scenario would require each tightly bound star to be at least twice the mass of our Sun, a binary system that has never been observed before.

More information:

This research was presented in a paper entitled “A detached stellar-mass black hole candidate in the globular cluster NGC 3201”, by B. Giesers et al., to appear in the journal Monthly Notices of the Royal Astronomical Society.

The team is composed of Benjamin Giesers (Georg-August-Universität Göttingen, Germany), Stefan Dreizler (Georg-August-Universität Göttingen, Germany), Tim-Oliver Husser (Georg-August-Universität Göttingen, Germany), Sebastian Kamann (Georg-August-Universität Göttingen, Germany; Liverpool John Moores University, Liverpool, United Kingdom), Guillem Anglada Escudé (Queen Mary University of London, United Kingdom), Jarle Brinchmann (Leiden Observatory, Leiden University, Leiden, The Netherlands; Universidade do Porto, CAUP, Porto, Portugal), C. Marcella Carollo (Swiss Federal Institute of Technology, ETH, Zurich, Switzerland) Martin M. Roth (Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany), Peter M. Weilbacher (Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany) and Lutz Wisotzki (Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and by Australia as a strategic partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.


ESOcast 146 Light: Odd Behaviour of Star Reveals Black Hole in Giant Star Cluster:

Research paper:

Information about the MUSE instrument on the VLT:

Photos of the VLT:

ESO’s Very Large Telescope (VLT):

Georg-August-Universität Göttingen:

Images, Videos,Text, Credits: ESO/Richard Hook/L. Calcada/Georg-August-Universität Göttingen/Stefan Dreizler/Benjamin Giesers/ESA/NASA/Digitized Sky Survey 2/Acknowledgement: Davide De Martin/IAU and Sky & Telescope.

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JUICE ground control gets green light to start development of Jupiter operations

ESA - JUICE Mission logo.

17 January 2018

ESA's Jupiter Icy Moons Explorer – JUICE – passed an important milestone, the ground segment requirements review, with flying colours, demonstrating that the teams are on track in the preparation of the spacecraft operations needed to achieve the mission's ambitious science goals.

Planned to launch in 2022, JUICE will embark on a 7.5-year long journey through the Solar System before arriving at Jupiter in 2029. There, it will spend three and a half years examining the giant planet and its environment, in particular investigating the Galilean moons Ganymede, Europa and Callisto, which are thought to conceal oceans of liquid water beneath their icy crusts.

Image above: Artist's impression of JUICE. Image Credits: Spacecraft: ESA/ATG medialab; Jupiter: NASA/ESA/J. Nichols (University of Leicester); Ganymede: NASA/JPL; Io: NASA/JPL/University of Arizona; Callisto and Europa: NASA/JPL/DLR.

To explore the atmosphere, magnetosphere and tenuous rings of Jupiter, as well as to characterise its three ocean-bearing moons, JUICE will sport ten state-of-the-art instruments. These include cameras, spectrometers, a sub-millimetre sounder, an ice-penetrating radar, an altimeter, a radio-science experiment, and sensors to monitor the magnetic fields and particle environment, as well as a radio interferometry experiment.

After confirmation of the spacecraft design and the first tests on individual pieces of the equipment, the mission has now gone through another important step, successfully showing that the ground teams that will operate JUICE and its suite of science instruments meet all the necessary requirements.

While space missions operate beyond the realm of our planet, the bulk of the work is actually conducted by engineers and scientists on Earth – the ground segment – who plan the activities, monitor, command and communicate with spacecraft so that they point in the desired directions to gather the data needed by the scientific community.

ESA's contribution to the ground segment of JUICE consists of the Mission Operations Centre (MOC), which is based at the European Space Operations Centre (ESOC) in Darmstadt, Germany, and also includes the ground stations and communications network; and the Science Operations Centre (SOC), based at the European Space Astronomy Centre (ESAC) near Madrid, Spain.

The ground segment requirements review, with the aim of assessing the overall implementation and progress of both the MOC and SOC, was completed on 13 December 2017.

"With this successful review, we confirmed that the JUICE ground segment is on track to deliver the great science expected by the community," says Olivier Witasse, ESA JUICE project scientist.

Jupiter's largest moons. Image Credits: NASA/JPL/DLR

As is the case for other missions, the MOC is responsible for commanding the spacecraft, monitoring its health and returning the data. Besides that, it is also in charge of a series of mission-specific functions, such as calculating the complex trajectory that will take JUICE to Jupiter, which includes five planetary gravity assist manoeuvres at Venus, Earth and Mars, as well as preparing for the spacecraft operations in the Jovian system, involving 26 flybys of Ganymede, Europa and Callisto, and eventually orbit injection around Ganymede.

The SOC is instead responsible for planning the science observations to be conducted with the ten instruments on-board of JUICE to maximise the scientific return of the mission. This entails the scheduling of spacecraft pointing to the various observation targets – Jupiter, the moons, the plasma environment, the magnetic field – and of the different operating modes to be employed by each instrument.

The review board verified that the mission requirements for the ground segment, including operations of both the spacecraft and payload, are fully met. Special attention was dedicated to the specific needs of the instruments that are part of JUICE's payload relevant to all phases of mission operations, from calibration measurements during the long cruise phase to the challenging operations in the Jupiter system.

As part of the review, the mission concept and the ground segment design were also addressed, as well as all details pertaining the organisation of work, from procurement to scheduling and overall management, making sure that potential critical areas have been identified and appropriate risk-mitigation measures have been defined.

After the successful review, the JUICE MOC and SOC will now proceed to the next phase, designing their respective implementation; a further review of the ground segment design is planned for the end of 2018.

"This year will be very crucial for the JUICE programme, with three key milestone to come: a Sun illumination test in April, which will simulate the conditions of the Venus fly-by on the full-scale thermal model of the spacecraft; the start of the engineering model test campaign in mid-2018; and the kick-off of the critical design review at the end of the year," says Giuseppe Sarri, ESA JUICE project manager.

"So far all preparation activities are running as expected, in line with the planned launch date on 20 May 2022."

For more information about JUICE mission, visit:

Images (mentioned), Text, Credits: ESA/Giuseppe Sarri/Olivier Witasse.


Columbus: 10 years a lab

ESA & DLR - Colombus Laboratory Module patch.

17 January 2018

In 1492 Columbus sailed the ocean blue… In 2008 another Columbus sailed into space.

Setting sail

Next month, Europe’s Columbus laboratory achieves 10 years in orbit. Circling our planet at 28 800 km/h, this element of the International Space Station created space history as the first European module dedicated to long-term research in weightlessness.

Throughout this year, we will be celebrating its many successes as a remarkable multi-user experiment facility. 

A past full of planning

Like the transatlantic voyages that Christopher Columbus made half a millennium ago, the Columbus module was meticulously planned, budgeted, scrapped and redesigned before getting the official blessing to build, ship and launch.

The laboratory ascended to orbit aboard Space Shuttle Atlantis from the Kennedy Space Center in Florida, USA on 7 February 2008. Nestling in the spaceplane’s cargo bay, Columbus was accompanied by a seven-man crew.

Lifting Columbus out of Atlantis' payload bay

On 11 February, the crew on the International Space Station captured the new arrival. At that moment, Columbus became Europe’s first permanent human outpost in orbit and Europe became a full partner of the International Space Station.

A decade of scientific research

Columbus houses as many disciplines as possible in a small volume, from astrobiology to solar science through metallurgy and psychology – more than 225 experiments have been carried out during this remarkable decade. Countless papers have been published drawing conclusions from experiments performed in Columbus.

Full Station

To mark the momentous occasion, the larger Columbus family of planners, builders, scientists, support teams and astronauts will gather to celebrate the lab at ESA’s technical heart in the Netherlands on 7 February. More to come on this event soon …

Related link:

For more information about Columbus module, visit:

Images, Text, Credits: European Space Agency (ESA)/S. Corvaja, 2008/NASA.

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