vendredi 8 mai 2015

NASA Selects Advanced Space Technology Concepts for Further Study

NASA logo.

May 8, 2015

NASA has selected 15 proposals for study under Phase I of the NASA Innovative Advanced Concepts (NIAC), a program that aims to turn science fiction into science fact through the development of pioneering technologies.

The chosen proposals cover a wide range of inventive concepts, selected for their potential to transform future aerospace missions.  Such transformational technology holds promise of accelerating NASA’s progress toward its goals of exploration beyond low-Earth orbit, and missions to an asteroid and Mars.

"The latest NIAC selections include a number of exciting concepts," said Steve Jurczyk, associate administrator for the Space Technology Mission Directorate (STMD) at NASA Headquarters in Washington. "We are working with American innovators to reimagine the future of aerospace and focus our investments on concepts to address challenges of current interests both in space and here on Earth."

NIAC Phase I awards are valued at approximately $100,000, providing awardees the funding needed to conduct a nine-month initial definition and analysis study of their concepts. If the basic feasibility studies are successful, awardees can apply for Phase II awards, valued up to $500,000 for two additional years of concept development.

"Most of the 2015 NIAC Phase I final candidates were outstanding, and choosing only 15 of them proved to be a challenge," said Jason Derleth, NIAC program executive. "We look forward to seeing how each new study will push boundaries and explore new approaches - that's what makes NIAC unique."

One of the selected proposals calls for the use of a soft-robotic rover for missions that can’t be accomplished with conventional power systems. This rover would resemble an eel with a short antenna on its back that harvests power from locally changing magnetic fields. The goal is to enable amphibious exploration of gas-giant moons like Europa.

Image above: This artist's rendering depicts 2015 NIAC Phase I Fellow Mason Peck's soft-robotic rover for planetary environments for missions that cannot be accomplished with conventional power systems. It resembles a squid, with tentacle-like structures that serve as electrodynamic 'power scavengers' to harvest power from locally changing magnetic fields. The goal is to enable amphibious exploration of gas-giant moons like Europa. Image Credits: NASA/Cornell University/NSF.

Another proposal will look at using two glider-like unmanned aerial vehicles connected by an ultra-strong cable at different altitudes that sail without propulsion. The vehicle would use wind shear in the lower stratosphere (approximately 60,000 ft.), similar to a kite surfer, where the upper aircraft provides lift and aerodynamic thrust, and the lower aircraft provides an upwind force to keep it from drifting downwind. If successful, this atmospheric satellite could remain in the stratosphere for years, enabling NASA's Earth science missions, monitoring capabilities or aircraft navigation at a fraction of the cost of orbital satellite networks.

Employing a novel mobility concept, the Cryogenic Reservoir Inventory by Cost-Effective Kinetically Enhanced Technology (CRICKET) proposal explores volatiles, such as hydrogen, nitrogen and water, stored in permanently shadowed regions on planetary bodies. Inexpensive robotic crawlers, hoppers and soccer-ball style buckey-bots would explore the surface of these dark regions for water and other compounds. Multiple bots could be used to develop a high-resolution map to aid in potentially using these resources.

NASA solicits visionary, long-term concepts for technological development based on their potential value to future and current space missions. The projects are chosen through a peer-review process that evaluates their potential, technical approach and benefits that can be realized in a reasonable timeframe. All concepts are very early in the development cycle and represent multiple technology areas, including aircraft propulsion, human life support, science instruments, unique robotic concepts and exploring other diverse technology paths needed to meet NASA's strategic goals.

NASA's early investments and partnerships with forward-thinking scientists, engineers and citizen inventors from across the nation will provide technological dividends and help maintain America's leadership in the global technology economy.

NIAC is part of NASA's Space Technology Mission Directorate, which innovates, develops, tests and flies hardware for use in NASA's future missions. During the next 18 months, the directorate will make significant new investments to address several high-priority challenges in achieving safe and affordable deep space exploration.

For a complete list of the selected proposals and more information about NIAC, visit:

For more information about NASA's investments in space technology, visit:

Image, Text, Credits: NASA/Joshua Buck/Karen Northon.


A Hubble Study of the Peculiar Asymmetry of NGC 949

NASA - Hubble Space Telescope patch.

May 8, 2015

This image provides the clearest ever view of galaxy NGC 949, which lies over 30 million light-years away in the constellation of Triangulum. The galaxy has an unusual shape, made more obscure due to its inclination. From our point of view, it is difficult to discern exactly what type of galaxy NGC 949 is, but it is certainly a disk galaxy of some kind, most likely a spiral.

NGC 949 was first discovered by Sir William Herschel on September 21, 1786, using an 18.7-inch reflecting telescope. The galaxy was one of about 3,000 objects Herschel cataloged as "nebulae" during an intense and systematic deep sky survey, the results of which eventually formed the bulk of the New General Catalogue (NGC).

Taken with Hubble’s Advanced Camera for Surveys (ACS), this image shows extraordinary detail. This detail allows us to see a strange asymmetric alignment in the dark lanes of dust that snake across the galaxy. The top-right half of the galaxy appears considerably more marbled with dust in this image; a curious observation explained by stars tending to favor locations towards the center of a galaxy, and dust preferring almost invariably to reside along the galactic plane.

When a galaxy is inclined as NGC 949 is, some regions — in this case the top-right — are tipped toward us and the light from the stars we see in these regions has had to travel through more dust. This causes the light to appear redder — the result of the same process that gives the sun’s light a red hue at dusk — or else disappear entirely, making the dust appear more prominent on that side of the galaxy.

Hubble orbiting the Earth

In the part tipped away from us, the light from the stars has had to pass through much less dust to reach us, so it appears brighter, and the dust is much less prominent. Were it possible to view NGC 949 from the opposite side, the apparent alignment of the dust would be reversed.

The scientific advantages of this effect were recently displayed in suitably stunning style in the M31 PHAT mosaic, which allowed astronomers to produce a partial three-dimensional dust map of M31 four times clearer than any previously attempted.

Related link:

Hubble’s Advanced Camera for Surveys (ACS):

For images and more information about Hubble, visit: and and

Image, Video, Text, Credits: ESA/Hubble & NASA/Ashley Morrow.

Best regards,

Quick Detour by NASA Curiosity Checks Ancient Valley and Rover Views Serene Sundown on Mars

NASA - Mars Science Laboratory (MSL) logo.

May 8, 2015

(Click on the image for enlarge)

Image above: This April 16, 2015, panorama from the Mast Camera on NASA's Curiosity Mars rover shows a detailed view toward two areas on lower Mount Sharp chosen for close-up inspection in subsequent weeks: "Mount Shields" and "Logan Pass." Image Credits: NASA/JPL-Caltech/MSSS.

Researchers slightly detoured NASA's Curiosity Mars rover from the mission's planned path in recent days for a closer look at a hillside site where an ancient valley had been carved out and refilled.

The rover made observations and measurements there to address questions about how the channel formed and filled. Then it resumed driving up Mount Sharp, where the mission is studying the rock layers. The layers reveal chapters in how environmental conditions and the potential to support microbial life changed in Mars' early history.

(Click on the image for enlarge)

Image above: A sweeping panorama combining 33 telephoto images into one Martian vista presents details of several types of terrain visible on Mount Sharp from a location along the route of NASA's Curiosity Mars rover. The component images were taken by the rover's Mast Camera on April 10, 2015. Image Credits: NASA/JPL-Caltech/MSSS.

Two new panoramas of stitched-together telephoto images from Curiosity's Mast Camera (Mastcam) present the increasingly hilly region the rover has been investigating, and more distant portions of Mount Sharp. These large images are online, with pan and zoom controls for exploring them, at:

Curiosity has been exploring on Mars since 2012. It reached the base of Mount Sharp last year after fruitfully investigating outcrops closer to its landing site and then trekking to the mountain. The main mission objective now is to examine successively higher layers of Mount Sharp. Curiosity spent several months examining the lowest levels of the mountain's basal geological unit, the Murray formation, at an outcrop called "Pahrump Hills." Then it set off toward a site called "Logan Pass," where the team anticipates a first chance to place the contact-science instruments at the end of the rover's arm onto a darker geological unit overlying or within the Murray formation.

"In pictures we took on the way from Pahrump Hills toward Logan Pass, some of the geologists on the team noticed a feature that looked like what's called an 'incised valley fill,' which is where a valley has been cut into bedrock and then filled in with other sediment," said Curiosity Project Scientist Ashwin Vasavada of NASA's Jet Propulsion Laboratory, Pasadena, California.

This unusual geometry of the rock layers was noted on the side of a rise called "Mount Shields," which sits northwest of the planned route to Logan Pass. The team chose in late April to divert the rover to the base of Mount Shields.

Image above: This map shows the route on lower Mount Sharp that NASA's Curiosity followed in April and early May 2015, in the context of the surrounding terrain. Numbers along the route identify the sol, or Martian day, on which it completed the drive reaching that point, as counted since its 2012 landing. Image Credits: NASA/JPL-Caltech/Univ. of Arizona.

"We wanted to investigate what cut into the mudstone bedrock, and what process filled it back in," Vasavada said. "The fill material looks like sand. Was the sand transported by wind or by water? What were the relative times for when the mudstone formed, when the valley was cut into it, when the cut was filled in?

“It’s exciting to see this on Mars for the first time," he continued. "Features like this on Earth capture evidence of change.  What in the environment changed to go from depositing one kind of sediment, to eroding it away in a valley, to then depositing a different kind of sediment? It’s a fascinating puzzle that Mars has left for us."

Scientists are examining the evidence collected at Mount Shields as the rover approaches its next study area, at Logan Pass.

NASA's Curiosity Rover Views Serene Sundown on Mars 

The sun dips to a Martian horizon in a blue-tinged sky in images sent home to Earth this week from NASA's Curiosity Mars rover.

For a single-frame scenic view, see:

Curiosity used its Mast Camera (Mastcam) to record the sunset during an evening of skywatching on April 15, 2015.

The imaging was done between dust storms, but some dust remained suspended high in the atmosphere. The sunset observations help researchers assess the vertical distribution of dust in the atmosphere.

"The colors come from the fact that the very fine dust is the right size so that blue light penetrates the atmosphere slightly more efficiently," said Mark Lemmon of Texas A&M University, College Station, the Curiosity science-team member who planned the observations. "When the blue light scatters off the dust, it stays closer to the direction of the sun than light of other colors does. The rest of the sky is yellow to orange, as yellow and red light scatter all over the sky instead of being absorbed or staying close to the sun."

Just as colors are made more dramatic in sunsets on Earth, Martian sunsets make the blue near the sun's part of the sky much more prominent, while normal daylight makes the rusty color of the dust more prominent.

Since its August 2012 landing inside Mars' Gale Crater, Curiosity has been studying the planet's ancient and modern environments.

Malin Space Science Systems, San Diego, built and operates Curiosity's Mastcam. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, built the rover and manages the project for NASA's Science Mission Directorate in Washington.

JPL, a division of the California Institute of Technology in Pasadena, built the rover and manages the project for NASA's Science Mission Directorate in Washington. For more information about Curiosity, visit: and

You can follow the mission on Facebook and Twitter at: and

Images (mentioned), Text, Credits: NASA/Dwayne Brown/JPL/Guy Webster/Tony Greicius.


Russian Spacecraft Re-Enters over Pacific Ocean

ROSCOSMOS - Russian Vehicles patch.

May 8, 2015

The Russian Federal Space Agency (Roscosmos) reports the Progress 59 cargo craft reentered the Earth’s atmosphere at 10:04 p.m. EDT over the central Pacific Ocean.

Image above: The unpiloted Russian ISS Progress 50 (50P) resupply ship undocks from the International Space Station.

The spacecraft was not carrying any supplies critical for the United States Operating Segment (USOS) of the station, and the break up and reenty of the Progress posed no threat to the ISS crew.   Both the Russian and USOS segments of the station continue to operate normally and are adequately supplied well beyond the next planned resupply flight.

Roscosmos statement:

Image, Text, Credit: NASA.


jeudi 7 mai 2015

Star Explosion Is Lopsided, Finds NASA's NuSTAR

NASA - Nuclear Spectroscopic Telescope Array (NuSTAR) patch.

May 7, 2015

NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, has found evidence that a massive star exploded in a lopsided fashion, sending ejected material flying in one direction and the core of the star in the other.

The findings offer the best proof yet that star explosions of this type, called Type II or core-collapse supernovae, are inherently asymmetrical, a phenomenon that had been difficult to prove before now.

Image above: The still unraveling remains of supernova 1987A are shown here in this image taken by NASA's Hubble Space Telescope. The bright ring consists of material ejected from the dying star before it detonated. The ring is being lit up by the explosion's shock wave. Image Credits: ESA/Hubble & NASA.

"Stars are spherical objects, but apparently the process by which they die causes their cores to be turbulent, boiling and sloshing around in the seconds before their demise," said Steve Boggs of the University of California, Berkeley, lead author of a new study on the findings, appearing in the May 8 issue of Science. "We are learning that this sloshing leads to asymmetrical explosions."

The supernova remnant in the study, called 1987A, is 166,000 light-years away. Light from the blast that created the remnant lit up skies above Earth in 1987. While other telescopes had found hints that this explosion was not spherical, NuSTAR found the "smoking gun" in the form of a radioisotope called titanium-44.

"Titanium is produced in the very heart of the explosion, so it traces the shape of the engine driving the disassembly of the star," said Fiona Harrison, the principal investigator of NuSTAR at the California Institute of Technology in Pasadena. "By looking at the shift of the energy of the X-rays coming from titanium, the NuSTAR data revealed that, surprisingly, most of the material is moving away from us."  

Last year, NuSTAR created detailed titanium-44 maps of another supernova remnant, called Cassiopeia A, also finding evidence of an asymmetrical explosion, though not to as great an extent as in 1987A. Together, these results suggest that lopsidedness is at the very root of core-collapse supernova.

When supernova 1987A first lit up our skies decades ago, telescopes around the world had a unique opportunity to watch the event unfold and evolve. Outer, ejected materials lit up first, followed by the innermost materials powered by radioactive isotopes, such as cobalt-56, which decayed into iron-56. In 2012, the European Space Agency's Integral satellite detected titanium-44 in 1987A. Titanium-44 continues to blaze in the supernova remnant due to its long lifetime of 85 years.

"In some ways, it is as if 1987A is still exploding in front of our eyes," said Boggs.

Image above: The plot of data from NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR (right), amounts to a "smoking gun" of evidence in the mystery of how massive stars explode. The observations indicate that supernovae belonging to a class called Type II or core-collapse blast apart in a lopsided fashion, with the core of the star hurtling in one direction, and the ejected material mostly expanding the other way (see diagram at left). Image Credits: NASA/JPL-Caltech/UC Berkeley.

NuSTAR brought a new tool to the study of 1987A. Thanks to the observatory's sharp high-energy X-ray vision, it has made the most precise measurements of titanium-44 yet. This radioactive material is produced at the core of a supernova, so it provides astronomers with a direct probe into the mechanisms of a detonating star.

The NuSTAR spectral data reveal that titanium-44 is moving away from us with a velocity of 1.6 million mph (2.6 million kilometers per hour). That indicates ejected material flung outward in one direction, while the compact core of the supernova, called a neutron star, seems to have kicked off in the opposite direction.

"These explosions are driven by the formation of a compact object, the remaining core of the star, and this seems to be connected to the core blasting one direction, and the ejected material, the other," said Boggs.

Video above: NuSTAR is showing that exploding stars slosh around before blasting apart. This 3-D computer simulation demonstrates how the supernova explosion might look. Video Credits NASA/JPL-Caltech.

Previous observations have hinted at the lopsided nature of supernova blasts, but it was impossible to confirm. Telescopes like NASA's Chandra X-ray Observatory, which sees lower-energy X-rays than NuSTAR, had spotted iron that had been heated in the 1987A blast, but it was not clear if the iron was generated in the explosion or just happened to have been in the vicinity.

“Radioactive titanium-44 glows in the X-rays no matter what and is only produced in the explosion,” said Brian Grefenstette, a co-author of the study at Caltech. "This means that we don’t have to worry about how the environment influenced the observations. We are able to directly observe the material ejected in the explosion.”

Future studies by NuSTAR and other telescopes should further illuminate the warped nature of supernovae. Is 1987A particularly askew, or in line with other objects in its class? A decades-old mystery continues to unravel before our eyes.

NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA's Jet Propulsion Laboratory, also in Pasadena, for NASA's Science Mission Directorate in Washington.

Related link:

NuSTAR created detailed titanium-44 maps:

For more information, visit:

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


Hubble Finds Giant Halo Around the Andromeda Galaxy

NASA - Hubble Space Telescope patch.

May 7, 2015

Scientists using NASA’s Hubble Space Telescope have discovered that the immense halo of gas enveloping the Andromeda galaxy, our nearest massive galactic neighbor, is about six times larger and 1,000 times more massive than previously measured. The dark, nearly invisible halo stretches about a million light-years from its host galaxy, halfway to our own Milky Way galaxy. This finding promises to tell astronomers more about the evolution and structure of majestic giant spirals, one of the most common types of galaxies in the universe.

“Halos are the gaseous atmospheres of galaxies. The properties of these gaseous halos control the rate at which stars form in galaxies according to models of galaxy formation," explained the lead investigator Nicolas Lehner of the University of Notre Dame, Indiana. The gargantuan halo is estimated to contain half the mass of the stars in the Andromeda galaxy itself, in the form of a hot, diffuse gas. If it could be viewed with the naked eye, the halo would be 100 times the diameter of the full moon in the sky. This is equivalent to the patch of sky covered by two basketballs held at arm’s length.

Image above: The Andromeda galaxy, our nearest massive galactic neighbor, is about six times larger and 1,000 times more massive than previously measured.
Image Credits: NASA/STScI.

The Andromeda galaxy lies 2.5 million light-years away and looks like a faint spindle, about 6 times the diameter of the full moon. It is considered a near-twin to the Milky Way galaxy.

Because the gas in Andromeda’s halo is dark, the team looked at bright background objects through the gas and observed how the light changed. This is a bit like looking at a glowing light at the bottom of a pool at night. The ideal background “lights” for such a study are quasars, which are very distant bright cores of active galaxies powered by black holes. The team used 18 quasars residing far behind Andromeda to probe how material is distributed well beyond the visible disk of the galaxy. Their findings were published in the May 4, 2015 edition of the Astrophysical Journal.

Earlier research from Hubble Cosmic Origins Spectrograph (COS)-Halos program studied 44 distant galaxies and found halos like Andromeda’s, but never before has such a massive halo been seen in a neighboring galaxy. Because the previously studied galaxies were much farther away, they appeared much smaller on the sky. Only one quasar could be detected behind each faraway galaxy, providing only one light anchor point to map their halo size and structure. With its close proximity to Earth and its correspondingly large footprint on the sky, Andromeda provides a far more extensive sampling of a lot of background quasars.

“As the light from the quasars travels toward Hubble, the halo’s gas will absorb some of that light and make the quasar appear a little darker in just a very small wavelength range,” explains co-investigator J. Christopher Howk, also of Notre Dame. “By measuring the dip in brightness in that range, we can tell how much gas there is between us and that quasar.”

The scientists used Hubble’s unique capability to study the ultraviolet light from the quasars. Ultraviolet light is absorbed by Earth’s atmosphere, which makes it difficult to observe with a ground-based telescope. The team drew from about 5 years worth of observations stored in the Hubble data archive to conduct this research. Many previous Hubble campaigns have used quasars to study gas much farther away than -- but in the general direction of -- Andromeda, so a treasure trove of data already existed.

But where did the giant halo come from? Large-scale simulations of galaxies suggest that the halo formed at the same time as the rest of Andromeda. The team also determined that it is enriched in elements much heavier than hydrogen and helium, and the only way to get these heavy elements is from exploding stars called supernovae.  The supernovae erupt in Andromeda’s star-filled disk and violently blow these heavier elements far out into space. Over Andromeda’s lifetime, nearly half of all the heavy elements made by its stars have been expelled far beyond the galaxy’s 200,000 light-year diameter stellar disk.

Hubble Space Telescope orbiting the Earth. Image Credit: NASA

What does this mean for our own galaxy? Because we live inside the Milky Way, scientists cannot determine whether or not such an equally massive and extended halo exists around our galaxy. It’s a case of not being able to see the forest for the trees. If the Milky Way does possess a similarly huge halo, the two galaxies’ halos may be nearly touching already and quiescently merging long before the two massive galaxies collide.  Hubble observations indicate that the Andromeda and Milky Way galaxies will merge to form a giant elliptical galaxy beginning about 4 billion years from now.

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

For images and more information about Hubble, visit: and and

For more information about Hubble’s Cosmic Origins Spectrograph (COS)-Halos, visit:

Images (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Rob Gutro/Lynn Jenner.

Best regards,

IRIS Celebrates 10,000th Orbit

NASA - IRIS Mission patch.

May 7, 2015

In this photo, NASA's Interface Region Imaging Spectrograph (IRIS) spacecraft captured several large solar prominences on the edge of the sun last week. On May 6, 2015, IRIS completed its 10,000th orbit of the Earth. IRIS, part of the agency’s Heliophysics System Observatory of missions, was launched in 2013 to track how energy and heat courses through a little understood region of the solar atmosphere called the interface region. On June 27, IRIS will celebrate its second year in orbit.

Artist's concept of IRIS spacecraft in orbit

Lockheed Martin’s Solar & Astrophysics Laboratory, Palo Alto, California, designed and manages the mission. The Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, built the telescope. Montana State University in Bozeman, Montana. helped design the spectrograph. NASA's Ames Research Center in Moffett Field, California, provides mission operations and ground data systems. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the Small Explorer Program for NASA's Science Mission Directorate in Washington, D.C. The Norwegian Space Centre provides regular downlinks of science data. Other contributors include the University of Oslo and Stanford University in Stanford, California.

For more information about IRIS, visit:

Images, Text, Credits: NASA/Sharon Lozano.


Proba-V maps world air traffic from space

ESA - Proba-V logo.

7 May 2015

As ESA’s Proba-V works quietly on its main task of monitoring vegetation growth across Earth, the minisatellite is also picking up something from a little higher: signals from thousands of aircraft.

Launched two years ago today, Proba-V has picked up upwards of 25 million positions from more than 15 000 separate aircraft.

Proba-V detecting aircraft

This is a technical world-first, demonstrating the feasibility of follow-on orbital constellations now being readied for operational aircraft monitoring.

“We stay operational 24 hours per day, seven days per week, apart from occasional maintenance or upgrading,” explains Toni Delovski of the DLR German Aerospace Center, overseeing the experiment.

“We’ve shown that detection of aircraft can work from space with no showstoppers, despite the fact that these signals were never designed to be picked up from so far away.

“In fact, the signals are beamed sideways from their host aircraft rather than omidirectionally, making them harder to detect from orbit.

“With a single satellite, our detection footprint is relatively small – about 1500 x 750 km – but for an operational service a constellation of satellites is envisaged to provide worldwide coverage.”

Proba-V satellite

Smaller than a cubic metre, Proba-V is nonetheless carrying several technology experiments as well as its main wide-swath Vegetation camera, which tracks changes in plant growth across the entire planet every two days.

DLR and Luxembourg’s SES company added an experiment to detect Automatic Dependent Surveillance Broadcast (ADS-B) aircraft signals from space.

These signals are regularly broadcast from aircraft, giving flight information such as speed, position and altitude. All aircraft entering European airspace are envisaged to carry ADS-B in the coming years.

DLR contributed the receiver carried aboard Proba-V, while SES has provided the experiment's ground segment, encompassing the processing needed to decode the signals, including compensating for factors such as frequency-shifting caused by the motion of Proba-V relative to the aircraft.

Proba-V liftoff

“The focus of the experiment is on the large parts of the world without radar and less dense air traffic,” adds Toni.

“In the event, we have also had very good detections in the much more densely trafficked airspace of the US, Western Europe and Southeast Asia.”

In those parts of the world with radar coverage, air traffic controllers can shepherd aircraft very precisely, with separation distances down to 5.5–9 km.

However in the rest of the world, such as over the Atlantic, minimum separation distance goes up by a factor of 10, to 93 km.

Space-based ADS-B offers a method of safely reducing separation distances everywhere, increasing global air traffic capacity while improving safety.

Proba-V readied for launch

DLR and SES are working with national air navigation service providers in Australia, Iceland, Portugal and Namibia to check Proba-V observations against the facts on the ground.

“We are still working to improve the system, with ongoing software upgrades, and investigating anomalies,” Toni adds. “Right now, some makes of aircraft are more easily detected than others, which typically comes down to the age and make of their ADS-B systems.” 

An operational ADS-B detection system is being hosted on the IridumNEXT constellation, while SES is working with ESA to determine the market for a European version.

 Contrails from air traffic

“If ADS-B from space is going to enter use on an operational, internationally certified basis, then we will certainly need a minimum of two systems,” Toni concludes.

“We couldn’t have a situation where the sole service suddenly goes down, and aircraft in the middle of the ocean need to spread out.”

Related links:

Proba-V tracking aircraft in flight from orbit:


SES TechCom:

ESA’S Vega launcher scores new success with Proba-V:

Images, Text, Credits: ESA/P.Carril/S. Corvaja/DLR/SES/CNES/Arianespace/Optique Video du CSG/Wikimedia/Kierano.


mercredi 6 mai 2015

Saturn Moon's Activity Could Be 'Curtain Eruptions'

NASA - Cassini International logo.

May 6, 2015

New research using data from NASA's Cassini mission suggests most of the eruptions from Saturn's moon Enceladus might be diffuse curtains rather than discrete jets. Many features that appear to be individual jets of material erupting along the length of prominent fractures in the moon's south polar region might be phantoms created by an optical illusion, according to the new study.

Icy Curtain Eruptions on Enceladus Create an Illusion of Discrete Jets

Video above: Recent research suggests much of the eruption activity on the surface of Saturn's moon Enceladus could be in the form of broad, curtain-like eruptions, rather than discrete jets. Video Credits: NASA/JPL-Caltech/SSI/PSI.

The research is being published on Thursday, May 7, in the journal Nature.

"We think most of the observed activity represents curtain eruptions from the 'tiger stripe' fractures, rather than intermittent geysers along them," said Joseph Spitale, lead author of the study and a participating scientist on the Cassini mission at the Planetary Science Institute in Tucson, Arizona. "Some prominent jets likely are what they appear to be, but most of the activity seen in the images can be explained without discrete jets."

In analyzing Cassini's images of the eruptions on Enceladus, Spitale and colleagues took particular note of the faint background glow present in most images. The brightest eruption features, which appear to be discrete jets, look to them to be superimposed intermittently upon this background structure.

The researchers modeled eruptions on Enceladus as uniform curtains along the tiger stripe fractures. They found that phantom brightness enhancements appear in places where the viewer is looking through a "fold" in the curtain. The folds exist because the fractures in Enceladus' surface are more wavy than perfectly straight. The researchers think this optical illusion is responsible for most of what appear to be individual jets.

"The viewing direction plays an important role in where the phantom jets appear," said Spitale. "If you rotated your perspective around Enceladus' south pole, such jets would seem to appear and disappear."

Phantom jets in simulated images produced by the scientists line up nicely with some of the features in real Cassini images that appear to be discrete columns of spray. The correspondence between simulation and spacecraft data suggests that much of the discrete-jet structure is an illusion, according to the researchers.

Images above: Researchers think an optical illusion is responsible for most -- but not all -- of what appear to be individual jets on Saturn's moon Enceladus. Some discrete jets are still required to explain Cassini's observations. Images Credits: NASA/JPL-Caltech/SSI/PSI.

Curtain eruptions occur on Earth where molten rock, or magma, gushes out of a deep fracture. These eruptions, which often create spectacular curtains of fire, are seen in places such as Hawaii, Iceland and the Galapagos Islands.

"Our understanding of Enceladus continues to evolve, and we've come to expect surprises along the way," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, California, who was not involved in the study. "This little ice world is becoming more exciting, not less, as we tease out new details about its subsurface ocean and astonishing geophysical activity."

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency's Science Mission Directorate in Washington. The Cassini imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about Cassini, visit: and and

Images (mentioned), Video (mentioned), Text, Credits: NASA/JPL/Preston Dyches/Tony Greicius.


ISS - Maintenance and Departure Preps Continue on Wednesday

ISS - Expedition 43 Mission patch.

May 6, 2015

Maintenance and experiment work continued on Wednesday for the Expedition 43 crew.

NASA astronauts Terry Virt spent the second consecutive day replacing components inside one of the station’s Carbon Dioxide Removal Assemblies (CDRA.) The CDRA system works to remove carbon dioxide from the cabin air, allowing for an environmentally safe crew cabin. Virts also did some preparatory work on a payload rack for a cellular biology experiment scheduled to launch on the next SpaceX mission.

One-Year crew member Scott Kelly participated in the Fine Motor Skills study and took some time out of his schedule to speak with the “Today Show” and his twin brother Mark Kelly.

Image above: NASA astronaut Terry Virts (center) shared this image after giving two of his Russian crew mates new zero-g haircuts.

Watch Scott Kelly talk to the “Today Show”:

ESA astronaut Samantha Cristoforetti continued the Triplelux-A experiment which aims to gain a better understanding of immune suppression in spaceflight. She also Russian cosmonaut Anton Shkaplerov in a checkout of the Sokol launch and entry suits that she, Shkaplerov and Virts will wear when they return to Earth next week.

Related links:

Cellular biology experiment:

Fine Motor Skills study:

Triplelux-A experiment:

For more information about the International Space Station (ISS), visit:

Image, Text, Credit: NASA.

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Big Ozone Holes Headed For Extinction By 2040

NASA - EOS AURA Mission patch.

May 6, 2015

The next three decades will see an end of the era of big ozone holes. In a new study, scientists from NASA Goddard Space Flight Center say that the ozone hole will be consistently smaller than 12 million square miles by the year 2040.

Big Ozone Holes Headed For Extinction By 2040

Ozone-depleting chemicals in the atmosphere cause an ozone hole to form over Antarctica during the winter months in the Southern Hemisphere. Since the Montreal Protocol agreement in 1987, emissions have been regulated and chemical levels have been declining.

However, the ozone hole has still remained bigger than 12 million square miles since the early 1990s, with exact sizes varying from year to year. The size of the ozone hole varies due to both temperature and levels of ozone-depleting chemicals in the atmosphere.

Artist's concept of the Aura spacecraft. Image Credit: NASA

In order to get a more accurate picture of the future size of the ozone hole, scientists used NASA’s AURA satellite to determine how much the levels of these chemicals in the atmosphere varied each year. With this new knowledge, scientists can confidently say that the ozone hole will be consistently smaller than 12 million square miles by the year 2040.

Scientists will continue to use satellites to monitor the recovery of the ozone hole and they hope to see its full recovery by the end of the century. Research: Inorganic chlorine variability in the Antarctic vortex and implications for ozone recovery.

Related links:

Journal: Geophysical Research: Atmospheres,  December 18, 2014. Link to paper:

For more information about AURA mission, visit: and

Image (mentioned), Video, Text, Credits: NASA/Goddard Space Flight Center.


Solar Dynamics Observatory Sees 'Cinco de Mayo' Solar Flare

NASA - Solar Dynamics Observatory (SDO) patch.

May 6, 2015

NASA's Solar Dynamics Observatory, which watches the sun constantly, captured these images of a significant solar flare – as seen in the bright flash on the left – peaking at 6:11 p.m. EDT on May 5, 2015. Each image shows a different wavelength of extreme ultraviolet light that highlights a different temperature of material on the sun. By comparing different images, scientists can better understand the movement of solar matter and energy during a flare. From left to right, the wavelengths are: visible light, 171 angstroms, 304 angstroms, 193 angstroms and 131 angstroms. Each wavelength has been colorized.

 SDO Observes a Cinco de Mayo Solar Flare

Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel. This flare is classified as an X2.7-class flare. X-class denotes the most intense flares, while the number provides more information about its strength. An X2 is twice as intense as an X1, an X3 is three times as intense, and so on.

For see the image in diferent wavelengths, visit:

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

Image, Text, Credits: NASA/SDO/Wiessinger/Sarah Loff.


SpaceX Demonstrates Astronaut Escape System for Crew Dragon Spacecraft

SpaceX logo.

May 6, 2015

A loud whoosh, faint smoke trail and billowing parachutes marked a successful demonstration Wednesday by SpaceX of its Crew Dragon spacecraft abort system – an important step in NASA’s endeavor to rebuild America's ability to launch crews to the International Space Station from U.S. soil. The successful test of the spacecraft’s launch escape capabilities proved the spacecraft’s ability to carry astronauts to safety in the unlikely event of a life-threatening situation on the launch pad.

Image above: The SpaceX Crew Dragon spacecraft descends launch test. Image Credits:Image Credits: NASA/Kim Shiflett.

The Crew Dragon simultaneously fired its eight SuperDraco engines at 9 a.m. EDT and leapt off a specially built platform at Cape Canaveral Air Force Station’s Space Launch Complex 40 in Florida. The engines fired for about six seconds, instantly producing about 15,000 pounds of thrust each and lifting the spacecraft out over the Atlantic Ocean before jettisoning its trunk, as planned, and parachuting safely into the ocean. The test lasted about two minutes from engine ignition to splashdown.

"This is a critical step toward ensuring crew safety for government and commercial endeavors in low-Earth orbit," said Kathy Lueders, manager of NASA’s Commercial Crew Program. "Congratulations to SpaceX on what appears to have been a successful test on the company's road toward achieving NASA certification of the Crew Dragon spacecraft for missions to and from the International Space Station.”

The flight test is a vital milestone in the company’s development effort and furthers its plan to meet a major requirement for the next generation of piloted spacecraft -- an escape system that can quickly and safely take crew members away from their rocket while on the pad and through their ascent to orbit. SpaceX can use the test data to help refine its aerodynamic and performance models, and its design, to help ensure crew safety throughout all phases of flight.

Video above: SpaceX Crew Dragon Spacecraft Takes Flight During Pad Abort Test at Cape Canaveral. Video Credit: NASA TV.

“SpaceX was founded with the goal of carrying people to space, and today’s pad abort test represented an important milestone in that effort,” said Gwynne Shotwell, SpaceX president and chief operating officer. “Our partnership with NASA has been essential for developing Crew Dragon, a spacecraft that we believe will be the safest ever flown. Today’s successful test will provide critical data as we continue toward crewed flights in 2017.”

The test was the first with a full-size developmental spacecraft using a complete set of eight SuperDraco engines in the demanding real-world conditions of a pad abort situation. SpaceX built the SuperDracos for pad and launch abort use. Each engine, the chambers of which are 3-D printed, burns hypergolic propellants monomethylhydrazine and nitrogen tetroxide.

More than 270 special instruments, including temperature sensors and accelerometers, which are instruments that measure acceleration, were strategically placed in and around the vehicle to measure a variety of stresses and acceleration effects. A test dummy, equipped with sensors, went along for the ride to measure the effects on the human body. To further maximize the value of the test, weights were placed inside the capsule at crew seat locations to replicate the mass of a crewed launch.

The trunk, an unpowered cylinder with stabilizing fins, detached from the spacecraft when it reached maximum altitude and fell back to Earth, while the capsule rotated on as planned for a couple seconds before unfurling its drogue parachutes, which then deployed the main parachutes. Boat crews have begun the process of retrieving the Crew Dragon from the ocean and returning it to land for further analysis.

Spacecraft development and certification through the Commercial Crew Program is performed through a new arrangement that encourages innovation and efficiency in the aerospace industry, bringing to the process the space agency’s expertise in the form of safety and performance requirements for the spacecraft, boosters and related systems.

Image above: The SpaceX Crew Dragon spacecraft descends under a parachute into the Atlantic Ocean Wednesday, May 6 following a simulated emergency at the launch pad. Image Credits: NASA/Kim Shiflett.

The pad abort test is a payment milestone funded by the Commercial Crew Program under a partnership agreement established with the company in 2012. The agency awarded contracts last year to Boeing and SpaceX to build their respective systems for flight tests and operational missions to the space station. Known as Commercial Crew Transportation Capability (CCtCap) contracts, the awards allow continued work on Boeing’s CST-100 and SpaceX’s Crew Dragon at a pace that is determined by their respective builders, but that also meets NASA's requirements and its goal of flying crews in 2017.

"Our partners have met many significant milestones and key development activities so far, and this pad abort test provides visual proof of one of the most critical safety requirements -- protecting a crew in the event of a major system failure," Lueders said.

NASA already is preparing the space station for commercial crew spacecraft and the larger station crews that will be enabled by SpaceX’s Crew Dragon and Boeing’s CST-100. NASA plans to use the new generation of privately developed and operated spacecraft to carry as many as four astronauts each mission, increasing the station crew to seven and doubling the amount of science that can be performed off the Earth, for the Earth.

For more information about NASA’s Commercial Crew Program, visit:

For the latest on commercial crew progress, bookmark the program’s blog at:

Images (mentioned), Video (mentioned), Text, Credits: NASA/Stephanie Schierholz/Kennedy Space Center/Stephanie Martin/SpaceX/John Taylor.


The space cargo ship will disintegrate in the atmosphere

ROSCOSMOS - Russian Vehicles patch.

May 6, 2015

Several countries, including Switzerland, closely followed the fall of the Russian cargo. The latter did not finally arrive around on earth, he will burn in the atmosphere.

The unmanned Progress cargo ship, plummeting into space from the loss of control there one week Russian operators must disintegrate Friday entering the atmosphere, said Wednesday the Russian space agency Roscosmos.

According to the calculations of specialists Roscosmos, it will disintegrate May 8th between 1:23 ET 9:55 p.m.. "The ship will burn in full through the layers of the atmosphere of the Earth, and only a few small fragments will reach the surface of the planet," the agency said in a statement.

Illustration image: Progress M-07M

A few hours after takeoff on April 28, the Progress M-27M, which was to dock Tuesday at the International Space Station that was to supply, has not responded to the Russian engineers started having uncontrollable reactions.

A commission of inquiry was mandated to establish the circumstances of the incident, which seems to have occurred at the time of separation between the ship and the rocket, it had estimated a week ago the vice president of Roscosmos, Alexander Ivanov.


The loss of this ship which cost almost half a billion Euros is a blow to the Russian space sector, a strategic area, already in the sights of power for stinging setbacks.

But it does not endanger the crew of the ISS which has several months of reserves. A supply ship Dragon, the US company SpaceX, should join the ISS at the earliest on June 19

Three to four Progress cargo ships are sent each year in space, bringing equipment and other supplies necessary for life on the ISS. After their mission, they fall and burn up in the atmosphere above the Pacific Ocean.

 Progress-M cargo atmosphere reentry trails seen from ISS

Image above: Progress de-orbit trails, normaly the time and place they de-orbit is tightly controlled. As usual, it was sent into the Pacific. That’s generally safe because the ocean is 160+ million square kilometers in area, and much of that real estate is empty of islands. But not in this case. You’re probably seeing the solar panels, antennae, and various other external bits being stripped off and leaving their own meteoric trails.

This same thing happens to meteors as well, but they’re moving much faster as they come in from interplanetary space, blasting in at a minimum of 11 km/sec (7 miles/sec). But the principle is the same.

The risk that Switzerland is affected by debris from the Progress M-27M is minimal, had said Monday the Federal Department of Defence, Protection of the Population and Sport (DDPS).

Related articles:

Progress M-27M began its fall to Earth ...:

Progress M-27M cargo craft launched to ISS:

As teams continue to monitor the spacecraft, additional updates and more information about the International Space Station will be available online at:

Images, Text, Credits: NASA/ROSCOSMOS/ATS/ Aerospace.


mardi 5 mai 2015

Saturn's Swirls and Shadows

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

May 5, 2015

Saturn's surface is painted with swirls and shadows. Each swirl here is a weather system, reminding us of how dynamic Saturn's atmosphere is.

Images taken in the near-infrared (like this one) permit us to peer through Saturn's methane haze layer to the clouds below. Scientists track the clouds and weather systems in the hopes of better understanding Saturn's complex atmosphere - and thus Earth's as well.

This view looks toward the sunlit side of the rings from about 17 degrees above the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on Feb. 8, 2015 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 752 nanometers.

The view was obtained at a distance of approximately 794,000 miles (1.3 million kilometers) from Saturn. Image scale is  47 miles (76 kilometers) per pixel.

For more information about Cassini mission, visit: and

Image, Text, Credits: NASA/JPL-Caltech/Space Science Institute/Tony Greicius.


NASA's LRO Moves Closer to the Lunar Surface

NASA - Lunar Reconnaissance Orbiter (LRO) patch.

May 5, 2015

NASA’s Lunar Reconnaissance Orbiter (LRO) has completed a maneuver that lowered the spacecraft’s orbit to within 20 kilometers (12 miles) above areas near the lunar South Pole, the closest the spacecraft has ever been to the lunar surface.

On Monday, May 4, 2015 flight controllers at NASA’s Goddard Space Flight Center in Greenbelt, Maryland performed two station keeping burns to change LRO’s orbit. The new orbit allows LRO to pass within 20 km (12 miles) of the South Pole and 165 km (103 miles) over the North Pole.

Image above: The image is a visualization of the LRO spacecraft as it passes low over the moon¹s surface near the lunar South Pole. From this vantage point LRO will continue to make detailed measurements of the lunar surface, and now from its lower orbit near the South Pole will make unique observations of selected areas. Image Credits: NASA/GSFC/SVS.

"We're taking LRO closer to the moon than we've ever done before, but the maneuver is similar to all other station keeping maneuvers, so the mission operations team knows exactly what to do,” said Steve Odendahl, LRO mission manager from NASA Goddard. 

To optimize science return, team members made the decision to change the orbit after determining that the new orbit configuration poses no danger to the spacecraft. LRO can operate for many years at this orbit.

The new orbit enables exciting new science and will see improved measurements near the South Pole. Two of the instruments benefit significantly from the orbit change. The return signal from the Lunar Orbiter Laser Altimeter (LOLA) laser shots will become stronger, producing a better signal. LOLA will obtain better measurements of specific regions near the South Pole that have unique illumination conditions. Diviner will be able to see smaller lunar features through the collection of higher resolution data.

“The lunar poles are still places of mystery where the inside of some craters never see direct sunlight and the coldest temperatures in the solar system have been recorded,” said John Keller, LRO project scientist at NASA Goddard. “By lowering the orbit over the South Pole, we are essentially magnifying the sensitivity of the LRO instruments which will help us understand the mechanisms by which water or other volatiles might be trapped there.”

Launched on June 18, 2009, LRO has collected a treasure trove of data with its seven powerful instruments, making an invaluable contribution to our knowledge about the moon. LRO is managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland, for the Science Mission Directorate at NASA Headquarters in Washington.

For more information on LRO visit:

Image (mentioned), Text, Credits: NASA’s Goddard Space Flight Center/Nancy Neal Jones/Lynn Jenner.


Astronomers Set a New Galaxy Distance Record

NASA / ESA - Hubble Space Telescope 25th Anniversary logo.

May 5, 2015

An international team of astronomers, led by Yale University and the University of California scientists, pushed back the cosmic frontier of galaxy exploration to a time when the universe was only 5 percent of its present age of 13.8 billion years. The team discovered an exceptionally luminous galaxy more than 13 billion years in the past and determined its exact distance from Earth using the combined data from NASA’s Hubble and Spitzer space telescopes, and the Keck I 10-meter telescope at the W. M. Keck Observatory in Hawaii. These observations confirmed it to be the most distant galaxy currently measured, setting a new record. The galaxy existed so long ago, it appears to be only about 100 million years old.

Image above: This is a Hubble Space Telescope image of the farthest spectroscopically confirmed galaxy observed to date (inset). It was identified in this Hubble image of a field of galaxies in the CANDELS survey (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey). NASA’s Spitzer Space Telescope also observed the unique galaxy. The W. M. Keck Observatory was used to obtain a spectroscopic redshift (z=7.7), extending the previous redshift record. Measurements of the stretching of light, or redshift, give the most reliable distances to other galaxies. This source is thus currently the most distant confirmed galaxy known, and it appears to also be one of the brightest and most massive sources at that time. The galaxy existed over 13 billion years ago. The near-infrared light image of the galaxy (inset) has been colored blue as suggestive of its young, and hence very blue, stars. The CANDELS field is a combination of visible-light and near-infrared exposures. Image Credits: NASA, ESA, P. Oesch (Yale U.).

The galaxy, EGS-zs8-1, was originally identified based on its particular colors in images from Hubble and Spitzer and is one of the brightest and most massive objects in the early universe. “It has already grown to more than 15 percent of the mass of our own Milky Way today,” said Pascal Oesch, lead author of the study from Yale University, New Haven, Connecticut.  “But it had only 670 million years to do so. The universe was still very young then.” The new distance measurement also enabled the astronomers to determine that EGS-zs8-1 was still forming stars very rapidly, about 80 times faster than our Milky Way galaxy today (which has a star formation rate of one star per year).

Only a handful of galaxies currently have accurate distances measured in this very early universe. “Every confirmation adds another piece to the puzzle of how the first generations of galaxies formed in the early universe,” said Pieter van Dokkum of Yale, second author of the study. “Only the most sensitive telescopes are powerful enough to reach to these large distances.” The discovery was only possible thanks to the relatively new Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) instrument on the Keck I telescope, which allows astronomers to efficiently study several galaxies at the same time.

Measuring galaxies at these extreme distances and characterizing their properties is a main goal of astronomers over the next decade. The observations see EGS-zs8-1 at a time when the universe was undergoing very important changes: the hydrogen between galaxies was transitioning from an opaque to a transparent state. “It appears that the young stars in the early galaxies like EGS-zs8-1 were the main drivers for this transition, called reionization,” said study co-author, Rychard Bouwens of the Leiden Observatory, Leiden, Netherlands.

Hubble and the sunrise over Earth

These new Hubble, Spitzer, and Keck observations together also pose new questions. They confirm that massive galaxies already existed early in the history of the universe, but that their physical properties were very different from galaxies seen around us today. Astronomers now have very strong evidence that the peculiar colors of early galaxies seen in the Spitzer images originate from a very rapid formation of massive, young stars, which interacted with the primordial gas in these galaxies.

The new observations underline the very exciting discoveries that NASA’s James Webb Space Telescope will enable when it is launched in 2018. In addition to pushing the cosmic frontier to even earlier cosmic times, the Webb telescope will be able to dissect the infrared galaxy light of EGS-zs8-1 seen with the Spitzer Space Telescope and will provide astronomers with much more detailed insights into its gas properties. “Our current observations indicate that it will be very easy to measure accurate distances to these distant galaxies in the future with the James Webb Space Telescope,” said Garth Illingworth of the University of California Santa Cruz. “The result of Webb’s upcoming measurements will provide a much more complete picture of the formation of galaxies at the cosmic dawn.”

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

For images and more information about Hubble, visit: and and

Image (mentioned), Video, Text, Credits: NASA/ESA/Goddard Space Flight Center/Rob Gutro.


Traffic Around Mars Gets Busy

NASA - Deep Space Network patch.

May 5, 2015

Fast Facts:

- Five active spacecraft are orbiting Mars, an increase of two since last summer

- An enhanced system warns if two orbiters may approach each other too closely

NASA has beefed up a process of traffic monitoring, communication and maneuver planning to ensure that Mars orbiters do not approach each other too closely.

Deep Space Network. Image Credits: NASA/JPL

Last year's addition of two new spacecraft orbiting Mars brought the census of active Mars orbiters to five, the most ever. NASA's Mars Atmosphere and Volatile Evolution (MAVEN) and India's Mars Orbiter Mission joined the 2003 Mars Express from ESA (the European Space Agency) and two from NASA: the 2001 Mars Odyssey and the 2006 Mars Reconnaissance Orbiter (MRO). The newly enhanced collision-avoidance process also tracks the approximate location of NASA's Mars Global Surveyor, a 1997 orbiter that is no longer working.

It's not just the total number that matters, but also the types of orbits missions use for achieving their science goals. MAVEN, which reached Mars on Sept. 21, 2014, studies the upper atmosphere. It flies an elongated orbit, sometimes farther from Mars than NASA's other orbiters and sometimes closer to Mars, so it crosses altitudes occupied by those orbiters. For safety, NASA also monitors positions of ESA's and India's orbiters, which both fly elongated orbits.

Image above: This graphic depicts the relative shapes and distances from Mars for five active orbiter missions plus the planet's two natural satellites. It illustrates the potential for intersections of the spacecraft orbits. Image Credit: NASA/JPL-Caltech.

"Previously, collision avoidance was coordinated between the Odyssey and MRO navigation teams," said Robert Shotwell, Mars Program chief engineer at NASA's Jet Propulsion Laboratory, Pasadena, California. "There was less of a possibility of an issue. MAVEN's highly elliptical orbit, crossing the altitudes of other orbits, changes the probability that someone will need to do a collision-avoidance maneuver. We track all the orbiters much more closely now. There's still a low probability of needing a maneuver, but it's something we need to manage."

ISRO Mars Orbiter Mission. Image Credit: ISRO

Traffic management at Mars is much less complex than in Earth orbit, where more than 1,000 active orbiters plus additional pieces of inactive hardware add to hazards. As Mars exploration intensifies, though, and will continue to do so with future missions, precautions are increasing. The new process was established to manage this growth as new members are added to the Mars orbital community in years to come.

All five active Mars orbiters use the communication and tracking services of NASA's Deep Space Network, which is managed at JPL. This brings trajectory information together, and engineers can run computer projections of future trajectories out to a few weeks ahead for comparisons.

ESA Mars Express. Image Credit: ESA

"It's a monitoring function to anticipate when traffic will get heavy," said Joseph Guinn, manager of JPL's Mission Design and Navigation Section. "When two spacecraft are predicted to come too close to one another, we give people a heads-up in advance so the project teams can start coordinating about whether any maneuvers are needed."

The amount of uncertainty in the predicted location of a Mars orbiter a few days ahead is more than a mile (more than two kilometers). Calculating projections for weeks ahead multiplies the uncertainty to dozens of miles, or kilometers. In most cases when a collision cannot be ruled out from projections two weeks ahead, improved precision in the forecasting as the date gets closer will rule out a collision with no need for avoidance action. Mission teams for the relevant orbiters are notified in advance when projections indicate a collision is possible, even if the possibility will likely disappear in subsequent projections. This situation occurred on New Year's weekend, 2015.

NASA 2001 Mars Odyssey. Image Credits: NASA/JPL-Caltech

On Jan. 3, automated monitoring determined that two weeks later, MAVEN and MRO could come within about two miles (three kilometers) of each other, with large uncertainties remaining in the exact passing distance. Although that was a Saturday, automatic messages went out to the teams operating the orbiters.

"In this case, before the timeline got short enough to need to plan an avoidance maneuver, the uncertainties shrank, and that ruled out the chance of the two spacecraft coming too near each other," Guinn said. This is expected to be the usual pattern, with the advance warning kicking off higher-level monitoring and initial discussions about options.

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

If preparations for an avoidance maneuver were called for, spacecraft commands would be written, tested and approved for readiness, but such commands would not be sent to a spacecraft unless projections a day or two ahead showed probability of a hazardous conjunction. The amount of uncertainty about each spacecraft's exact location varies, so the proximity considered unsafe also varies. For some situations, a day-ahead projection of two craft coming within about 100 yards (100 meters) of each other could trigger a maneuver.

The new formal collision-avoidance process for Mars is part of NASA's Multi-Mission Automated Deep-Space Conjunction Assessment Process. A side benefit of it is that information about when two orbiters will be near each other -- though safely apart -- could be used for planning coordinated science observations. The pair could look at some part of Mars or its atmosphere from essentially the same point of view simultaneously with complementary instruments.

NASA Mars Global Surveyor. Image Credit: NASA

Odyssey, MRO and MAVEN -- together with NASA's two active Mars rovers, Opportunity and Spirit -- are part of NASA's robotic exploration of Mars that is preparing the way for human-crewed missions there in the 2030s and later, in NASA's Journey to Mars strategy.

NASA's Goddard Space Flight Center manages the MAVEN project for the NASA Science Mission Directorate, Washington. MAVEN's principal investigator is based at the University of Colorado's Laboratory for Atmospheric and Space Physics. JPL, a division of the California Institute of Technology in Pasadena, manages NASA's Mars Exploration Program and the Odyssey and MRO projects for the Science Mission Directorate. Lockheed Martin Space Systems, Denver, built all three NASA Mars orbiters.

For more about NASA's Mars Exploration Program, visit: and

For more information about NASA Mars Atmosphere and Volatile Evolution (MAVEN), visit:

For more information about ISRO Mars Orbiter Mission, visit:

For more information about ESA Mars Express, visit:

For more information about NASA 2001 Mars Odyssey, visit:

For more information about NASA Mars Reconnaissance Orbiter (MRO), visit:

For more information about NASA Mars Global Surveyor, visit:

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

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