Exoplanet Has Smothering Stratosphere Without Water

A NASA-led team has found evidence that the oversized exoplanet WASP-18b is wrapped in a smothering stratosphere loaded with carbon monoxide and devoid of water. The findings come from a new analysis of observations made by the Hubble and Spitzer space telescopes.

The formation of a stratosphere layer in a planet's atmosphere is attributed to "sunscreen"-like molecules, which absorb ultraviolet (UV) and visible radiation coming from the star and then release that energy as heat. The new study suggests that the "hot Jupiter" WASP-18b, a massive planet that orbits very close to its host star, has an unusual composition, and the formation of this world might have been quite different from that of Jupiter and gas giants in other planetary systems.

"The composition of WASP-18b defies all expectations," said Kyle Sheppard of NASA's Goddard Space Flight Center in Greenbelt, Maryland, lead author of the paper published in the Astrophysical Journal Letters. "We don't know of any other extrasolar planet where carbon monoxide so completely dominates the upper atmosphere."

Quick Facts:

Planet: WASP-18b

Mass: 10 times the mass of Jupiter

Distance from Earth: 325 light-years

Orbital period: 23 hours

On Earth, ozone absorbs UV in the stratosphere, protecting our world from a lot of the Sun's harmful radiation. For the handful of exoplanets with stratospheres, the absorber is typically thought to be a molecule such as titanium oxide, a close relative of titanium dioxide, used on Earth as a paint pigment and sunscreen ingredient.

The researchers looked at data collected for WASP-18b, located 325 light-years from Earth, as part of a survey to find exoplanets with stratospheres. The heavyweight planet, which has the mass of 10 Jupiters, has been observed repeatedly, allowing astronomers to accumulate a relatively large trove of data. This study analyzed five eclipses from archived Hubble data and two from Spitzer.

From the light emitted by the planet's atmosphere at infrared wavelengths, beyond the visible region, it's possible to identify the spectral fingerprints of water and some other important molecules. The analysis revealed WASP-18b's peculiar fingerprint, which doesn't resemble any exoplanet examined so far. To determine which molecules were most likely to match it, the team carried out extensive computer modeling.

"The only consistent explanation for the data is an overabundance of carbon monoxide and very little water vapor in the atmosphere of WASP-18b, in addition to the presence of a stratosphere," said Nikku Madhusudhan a co-author of the study from the University of Cambridge, United Kingdom. "This rare combination of factors opens a new window into our understanding of physical and chemical processes in exoplanetary atmospheres."

The findings indicate that WASP-18b has hot carbon monoxide in the stratosphere and cooler carbon monoxide in the layer of the atmosphere below, called the troposphere. The team determined this by detecting two types of carbon monoxide signatures, an absorption signature at a wavelength of about 1.6 micrometers and an emission signature at about 4.5 micrometers. This is the first time researchers have detected both types of fingerprints for a single type of molecule in an exoplanet's atmosphere.

In theory, another possible fit for the observations is carbon dioxide, which has a similar fingerprint. The researchers ruled this out because if there were enough oxygen available to form carbon dioxide, the atmosphere also should have some water vapor.

To produce the spectral fingerprints seen by the team, the upper atmosphere of WASP-18b would have to be loaded with carbon monoxide. Compared to other hot Jupiters, this planet's atmosphere likely would contain 300 times more "metals," or elements heavier than hydrogen and helium. This extremely high metallicity would indicate WASP-18b might have accumulated greater amounts of solid ices during its formation than Jupiter, suggesting it may not have formed the way other hot Jupiters did.

"The expected launch of the James Webb Space Telescope and other future space-based observatories will give us the opportunity to follow up with even more powerful instruments and to continue exploring the amazing array of exoplanets out there," said Avi Mandell, an exoplanet scientist at Goddard and the second author of the paper.

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NASA Finds VA Metro Area Is Sinking Unevenly

A new NASA-led study shows that land in the Hampton Roads, Virginia, metropolitan area is sinking at highly uneven rates, with a few trouble spots subsiding 7 to 10 times faster than the area average. Whereas earlier estimates had suggested the area is subsiding evenly, the new study found that major differences in subsidence rates occur only a few miles apart.

Hampton Roads has one of the highest rates of relative sea level rise -- the combined effects of sinking land and rising seas -- along the U.S. East Coast, about an inch (23 millimeters) every five years. It has experienced a steady and dramatic increase in high-tide flooding over the last 90 years. Accurate, local subsidence maps are necessary for the area to prepare for increasing flood risks in the future. The region comprises seven Virginia cities, including Norfolk and Virginia Beach, as well as Naval Station Norfolk, the country's largest naval base.

The new study, published in the journal Scientific Reports, found that much-higher-than-average subsidence is occurring at Craney Island, a depository for material dredged from shipping channels, and at the Norfolk Naval Shipyard, where the subsidence was most likely related to local construction during the study period. In other areas with similarly high subsidence rates, the causes of the sinking are not known.

Researchers from NASA's Jet Propulsion Laboratory in Pasadena, California, and Old Dominion University (ODU) in Norfolk found the variations in subsidence by analyzing synthetic aperture radar (SAR) images acquired between 2007 and 2011 by the Japan Aerospace Exploration Agency's ALOS-1 satellite. Processing the data with state-of-the-art image processing techniques, the researchers were able to document how the land surface had changed from the time of the first ALOS-1 image to 2011. To tie in that relative data set with existing, lower-resolution maps of earlier subsidence, as well as to put the results into a framework already familiar to decision-makers, the researchers developed a new strategy to integrate the processed SAR measurements with Global Positioning System (GPS) observations.

The result was the first high-resolution estimates of vertical land motion in Hampton Roads. The new estimates have a spatial resolution of about 100 feet (30 meters), whereas earlier estimates were based on data from GPS stations located 10 to 15 miles apart (about 20 kilometers).

The production of the new maps was a pilot project between JPL and ODU to assess the feasibility of using space-borne SAR data to map subsidence in Hampton Roads, according to lead author David Bekaert of JPL. He noted that the techniques developed to make these maps integrating SAR and GPS measurements could be used to map subsidence at other locations.

The ALOS-1 data set used in this study is relatively small, with the satellite acquiring an image of the area only once every 46 days at best. Bekaert and coauthors look forward to using data from the future NASA-Indian Space Research Organizaton Synthetic Aperture Radar (NISAR) mission, scheduled to launch in 2021, and from the European Space Agency's Sentinel-1 constellation, which currently acquires a new image of the Hampton Roads area every 12 days. NISAR will also acquire an image every 12 days, but because of its longer operating wavelength and higher resolution, it is well placed to extend subsidence mapping into more challenging rural areas and wetlands.

"Continuing, regularly acquired SAR data will allow us to reduce the uncertainty in our subsidence rate estimates, which is important for decision-making," Bekaert said.

Coauthor Ben Hamlington (ODU) noted, "Information regarding subsidence should be incorporated into land use decisions and taken into consideration for future planning." He has presented preliminary findings from this study to several planning and emergency management committees in Hampton Roads.

Hamlington said, "We had a need for high-resolution images of subsidence, but we didn't have the expertise and technology to do the analysis ourselves here at ODU. Collaborating with JPL helped us build capacity for the future, and also get immediate results."

NASA's associate program manager for disasters, John Murray of NASA's Langley Research Center in Hampton, connected the ODU and JPL scientists. The study was funded by NASA's Earth Science Disasters Program and the Commonwealth Center for Recurrent Flooding Resiliency, jointly operated by ODU and the College of William & Mary, Norfolk.

The paper in Scientific Reports is titled "Spaceborne Synthetic Aperture Radar Survey of Subsidence in Hampton Roads, Virginia (USA)."

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NASA Builds its Next Mars Rover Mission

In just a few years, NASA's next Mars rover mission will be flying to the Red Planet.

At a glance, it looks a lot like its predecessor, the Curiosity Mars rover. But there's no doubt it's a souped-up science machine: It has seven new instruments, redesigned wheels and more autonomy. A drill will capture rock cores, while a caching system with a miniature robotic arm will seal up these samples. Then, they'll be deposited on the Martian surface for possible pickup by a future mission.

This new hardware is being developed at NASA's Jet Propulsion Laboratory, Pasadena, California, which manages the mission for the agency. It includes the Mars 2020 mission's cruise stage, which will fly the rover through space, and the descent stage, a rocket-powered "sky crane" that will lower it to the planet's surface. Both of these stages have recently moved into JPL's Spacecraft Assembly Facility.

Mars 2020 relies heavily on the system designs and spare hardware previously created for Mars Science Laboratory's Curiosity rover, which landed in 2012. Roughly 85 percent of the new rover's mass is based on this "heritage hardware."

"The fact that so much of the hardware has already been designed -- or even already exists -- is a major advantage for this mission," said Jim Watzin, director of NASA's Mars Exploration Program. "It saves us money, time and most of all, reduces risk."

Despite its similarities to Mars Science Laboratory, the new mission has very different goals. Mars 2020's instruments will seek signs of ancient life by studying terrain that is now inhospitable, but once held flowing rivers and lakes, more than 3.5 billion years ago.

To achieve these new goals, the rover has a suite of cutting-edge science instruments. It will seek out biosignatures on a microbial scale: An X-ray spectrometer will target spots as small as a grain of table salt, while an ultraviolet laser will detect the "glow" from excited rings of carbon atoms. A ground-penetrating radar will be the first instrument to look under the surface of Mars, mapping layers of rock, water and ice up to 30 feet (10 meters) deep, depending on the material.

The rover is getting some upgraded Curiosity hardware, including color cameras, a zoom lens and a laser that can vaporize rocks and soil to analyze their chemistry.

"Our next instruments will build on the success of MSL, which was a proving ground for new technology," said George Tahu, NASA's Mars 2020 program executive. "These will gather science data in ways that weren't possible before."

The mission will also undertake a marathon sample hunt: The rover team will try to drill at least 20 rock cores, and possibly as many as 30 or 40, for possible future return to Earth.

"Whether life ever existed beyond Earth is one of the grand questions humans seek to answer," said Ken Farley of JPL, Mars 2020's project scientist. "What we learn from the samples collected during this mission has the potential to address whether we're alone in the universe."

JPL is also developing a crucial new landing technology called terrain-relative navigation. As the descent stage approaches the Martian surface, it will use computer vision to compare the landscape with pre-loaded terrain maps. This technology will guide the descent stage to safe landing sites, correcting its course along the way.

A related technology called the ranger trigger will use location and velocity to determine when to fire the spacecraft's parachute. That change will narrow the landing ellipse by more than 50 percent.

"Terrain-relative navigation enables us to go to sites that were ruled too risky for Curiosity to explore," said Al Chen of JPL, the Mars 202 entry, descent and landing lead. "The range trigger lets us land closer to areas of scientific interest, shaving miles -- potentially as much as a year -- off a rover's journey."

This approach to minimizing landing errors will be critical in guiding any future mission dedicated to retrieving the Mars 2020 samples, Chen said.

Site selection has been another milestone for the mission. In February, the science community narrowed the list of potential landing sites from eight to three. Those three remaining sites represent fundamentally different environments that could have harbored primitive life: an ancient lakebed called Jezero Crater; Northeast Syrtis, where warm waters may have chemically interacted with subsurface rocks; and a possible hot springs at Columbia Hills.

All three sites have rich geology and may potentially harbor signs of past microbial life. A final landing site decision is still more than a year away.

"In the coming years, the 2020 science team will be weighing the advantages and disadvantages of each of these sites," Farley said. "It is by far the most important decision we have ahead of us."

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New York Students to Speak with NASA Astronauts on Space Station

Students at U.S. Military Academy in West Point, New York, will speak with NASA astronauts living, working and doing research aboard the International Space Station at 9:15 a.m. EST Monday, Nov. 27.

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NASA to Highlight Science on Next Resupply Mission to Space Station

NASA will host a media teleconference at 1 p.m. EST Wednesday, Nov. 29, to discuss a number of science investigations and instruments launching to the International Space Station on the next SpaceX commercial resupply mission.

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Drone Race: Human Versus Artificial Intelligence

Drone racing is a high-speed sport demanding instinctive reflexes -- but humans won't be the only competitors for long.

Researchers at NASA's Jet Propulsion Laboratory in Pasadena, California, put their work to the test recently. Timing laps through a twisting obstacle course, they raced drones controlled by artificial intelligence (A.I.) against a professional human pilot.

The race, held on Oct. 12, capped off two years of research into drone autonomy funded by Google. The company was interested in JPL's work with vision-based navigation for spacecraft -- technologies that can also be applied to drones. To demonstrate the team's progress, JPL set up a timed trial between their A.I. and world-class drone pilot Ken Loo.

The team built three custom drones (dubbed Batman, Joker and Nightwing) and developed the complex algorithms the drones needed to fly at high speeds while avoiding obstacles. These algorithms were integrated with Google's Tango technology, which JPL also worked on.

The drones were built to racing specifications and could easily go as fast as 80 mph (129 kph) in a straight line. But on the obstacle course set up in a JPL warehouse, they could only fly at 30 or 40 mph (48 to 64 kph) before they needed to apply the brakes.

"We pitted our algorithms against a human, who flies a lot more by feel," said Rob Reid of JPL, the project's task manager. "You can actually see that the A.I. flies the drone smoothly around the course, whereas human pilots tend to accelerate aggressively, so their path is jerkier."

Compared to Loo, the drones flew more cautiously but consistently. Their algorithms are still a work in progress. For example, the drones sometimes moved so fast that motion blur caused them to lose track of their surroundings.

Loo attained higher speeds and was able to perform impressive aerial corkscrews. But he was limited by exhaustion, something the A.I.-piloted drones didn't have to deal with.

"This is definitely the densest track I've ever flown," Loo said. "One of my faults as a pilot is I get tired easily. When I get mentally fatigued, I start to get lost, even if I've flown the course 10 times."

While the A.I. and human pilot started out with similar lap times, after dozens of laps, Loo learned the course and became more creative and nimble. For the official laps, Loo averaged 11.1 seconds, compared to the autonomous drones, which averaged 13.9 seconds.

But the latter was more consistent overall. Where Loo's times varied more, the A.I was able to fly the same racing line every lap.

"Our autonomous drones can fly much faster," Reid said. "One day you might see them racing professionally!"

Without a human pilot, autonomous drones typically rely on GPS to find their way around. That's not an option for indoor spaces like warehouses or dense urban areas. A similar challenge is faced by autonomous cars.

Camera-based localization and mapping technologies have various potential applications, Reid added. These technologies might allow drones to check on inventory in warehouses or assist search and rescue operations at disaster sites. They might even be used eventually to help future robots navigate the corridors of a space station.

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Cassini Image Mosaic: A Farewell to Saturn

In a fitting farewell to the planet that had been its home for over 13 years, the Cassini spacecraft took one last, lingering look at Saturn and its splendid rings during the final leg of its journey and snapped a series of images that has been assembled into a new mosaic. 

Cassini's wide-angle camera acquired 42 red, green and blue images, covering the planet and its main rings from one end to the other, on September 13, 2017. Imaging scientists stitched these frames together to make a natural color view. The scene also includes the moons Prometheus, Pandora, Janus, Epimetheus, Mimas and Enceladus.

There is much to remember and celebrate in marking the end of the mission. Cassini's exploration of Saturn and its environs was deep, comprehensive and historic.

"Cassini's scientific bounty has been truly spectacular -- a vast array of new results leading to new insights and surprises, from the tiniest of ring particles to the opening of new landscapes on Titan and Enceladus, to the deep interior of Saturn itself," said Robert West, Cassini's deputy imaging team leader at NASA's Jet Propulsion Laboratory in Pasadena, California.

The Cassini imaging team had been planning this special farewell view of Saturn for years. For some, when the end finally came, it was a difficult goodbye.

"It was all too easy to get used to receiving new images from the Saturn system on a daily basis, seeing new sights, watching things change," said Elizabeth Turtle, an imaging team associate at the Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland. "It was hard to say goodbye, but how lucky we were to be able to see it all through Cassini's eyes!"

For others, Cassini's farewell to Saturn is reminiscent of another parting from long ago.

"For 37 years, Voyager 1's last view of Saturn has been, for me, one of the most evocative images ever taken in the exploration of the solar system," said Carolyn Porco, former Voyager imaging team member and Cassini's imaging team leader at the Space Science Institute in Boulder, Colorado. "In a similar vein, this 'Farewell to Saturn' will forevermore serve as a reminder of the dramatic conclusion to that wondrous time humankind spent in intimate study of our Sun's most iconic planetary system."

Launched in 1997, the Cassini spacecraft orbited Saturn from 2004 to 2017. The mission made numerous dramatic discoveries, including the surprising geologic activity on Saturn's moon Enceladus and liquid methane seas on Saturn's largest moon, Titan. Cassini ended its journey with a dramatic plunge into Saturn's atmosphere on Sept. 15, 2017, returning unique science data until it lost contact with Earth.

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. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the U.S., England, France, and Germany. The imaging operations center and team leader are based at the Space Science Institute in Boulder, Colorado.

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NASA Links Port-City Sea Levels to Regional Ice Melt

A new NASA tool links changes in sea level in 293 global port cities to specific regions of melting land ice, such as southern Greenland and the Antarctic Peninsula. It is intended to help coastal planners prepare for rising seas in the decades to come.

All coastal cities will see some impacts of global sea level rise. But the new tool shows that, for example, New York City is more strongly affected by melting ice in northeastern Greenland than in southwestern Greenland; while Sydney has a greater risk from the rapidly melting Antarctic Peninsula than from East Antarctica.

A paper describing the new tool, titled "Should coastal planners have concern over where land ice is melting?," was recently published in the journal Science Advances. The research team is Eric Larour, Erik Ivins and Surendra Adhikari of NASA's Jet Propulsion Laboratory in Pasadena, California.

Melting ice and rising ocean temperatures contribute about evenly to global sea level rise today. Individual cities are also affected by local conditions such as land sinking. Other Web-based resources such as the U.S. Climate Resilience Toolkit address some of these issues, but the new NASA tool is the only resource to match specific melting ice locations with their effects on the world's ports.

Water from melted ice on land doesn't spread evenly across the world's oceans because of a gravitational push-pull between ice and ocean. As a melting glacier or ice sheet dwindles, it loses mass, causing its local gravitational pull on nearby ocean water to diminish. Seawater that had been pulled toward the ice by the force of gravity flows away -- in other words, sea level drops in the vicinity of a melting glacier but rises farther away. When this spatial pattern can be attributed to a given glacier or ice sheet, it is known as a sea level fingerprint.

To calculate this and other influences on sea level such as Earth's rotation, Larour and his colleagues used a dynamic mathematical formula called the adjoint method, which is used in seismic and meteorological studies. The method enables fast computation of the sensitivity of a model's output to its inputs -- in this case, the sensitivity of sea level to ice melting. They used the method with JPL's well-tested computer model of ice sheet melting, the Ice Sheet System Model, to develop their new tool, called Gradient Fingerprint Mapping.

Users of the tool need no specialized training or extreme computer power; they simply download it, input data or projections of ice loss, and let it evolve the shifting ice and water patterns forward into the future. The result: a detailed profile of the sensitivity of sea level at any of these cities to changes in ice anywhere in the world.

Calculations of sea level fingerprints have been made in previous studies but tended to be cumbersome and spatially coarse, Larour said. The new tool provides an overall mechanism for rapidly computing high-resolution results using a variety of potential data sets.

Gradient Fingerprint Mapping is not dependent on a particular climate change scenario, Larour said. "You can apply the method to any type of melting scenario that you want." That means it will retain its utility as improved projections of ice loss become available in the future.

The computations show that the specific location of mass loss in Greenland is crucial, as it greatly affects the local sea level predictions for many major coastal cities in North America and Europe. The spatial details of Antarctic melting are important for areas south of the equator in South America, Africa and South Asia.

Among some intriguing results, Larour said, are those for New York, London and Oslo. Greenland's northeastern ice stream was shown to have an outsized effect on New York's local sea level, but the island's southern glaciers had little influence. London was more strongly affected by Greenland's northwestern and western glaciers. And Norway is so close to Greenland, the island's gravitational fingerprint is contributing to sea level decrease in Oslo.

The authors note that ocean dynamics can accelerate or offset the changes in sea level from gravitational fingerprints -- particularly in New York, where the contribution of melting ice to accelerated sea level rise is minor compared to other sources.

"This is really a new capability," Larour said. "Now a coastal planner can understand and see how the melting or growing of a given ice sheet could be detrimental or beneficial to a specific location."

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Solar System's First Interstellar Visitor Dazzles Scientists

Astronomers recently scrambled to observe an intriguing asteroid that zipped through the solar system on a steep trajectory from interstellar space-the first confirmed object from another star.

Now, new data reveal the interstellar interloper to be a rocky, cigar-shaped object with a somewhat reddish hue. The asteroid, named 'Oumuamua by its discoverers, is up to one-quarter mile (400 meters) long and highly-elongated-perhaps 10 times as long as it is wide. That aspect ratio is greater than that of any asteroid or comet observed in our solar system to date. While its elongated shape is quite surprising, and unlike asteroids seen in our solar system, it may provide new clues into how other solar systems formed.

The observations and analyses were funded in part by NASA and appear in the Nov. 20 issue of the journal Nature. They suggest this unusual object had been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with our star system.

"For decades we've theorized that such interstellar objects are out there, and now - for the first time - we have direct evidence they exist," said Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate in Washington. "This history-making discovery is opening a new window to study formation of solar systems beyond our own."

Immediately after its discovery, telescopes around the world, including ESO'sVery Large Telescopein Chile, were called into action to measure the object's orbit, brightness and color. Urgency for viewing from ground-based telescopes was vital to get the best data.

Combining the images from theFORS instrumenton the ESO telescope using four different filters with those of other large telescopes, a team of astronomers led by Karen Meech of the Institute for Astronomy in Hawaii found that 'Oumuamua varies in brightness by a factor of 10 as it spins on its axis every 7.3 hours. No known asteroid or comet from our solar system varies so widely in brightness, with such a large ratio between length and width. The most elongated objects we have seen to date are no more than three times longer than they are wide.

"This unusually big variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape," said Meech. "We also found that it had a reddish color, similar to objects in the outer solar system, and confirmed that it is completely inert, without the faintest hint of dust around it."

These properties suggest that 'Oumuamua is dense, composed of rock and possibly metals, has no water or ice, and that its surface was reddened due to the effects of irradiation from cosmic rays over hundreds of millions of years.

A few large ground-based telescopes continue to track the asteroid, though it's rapidly fading as it recedes from our planet. Two of NASA's space telescopes (HubbleandSpitzer) are tracking the object the week of Nov. 20. As of Nov. 20, 'Oumuamua is travelling about 85,700 miles per hour (38.3 kilometers per second) relative to the Sun. Its location is approximately 124 million miles (200 million kilometers) from Earth -- the distance between Mars and Jupiter - though its outbound path is about 20 degrees above the plane of planets that orbit the Sun. The object passed Mars's orbit around Nov. 1 and will pass Jupiter's orbit in May of 2018. It will travel beyond Saturn's orbit in January 2019; as it leaves our solar system, 'Oumuamua will head for the constellation Pegasus.

Observations from large ground-based telescopes will continue until the object becomes too faint to be detected, sometime after mid-December. NASA's Center for Near-Earth Object Studies (CNEOS) continues to take all available tracking measurements to refine the trajectory of 1I/2017 U1 as it exits our solar system.

This remarkable object was discovered Oct. 19by the University of Hawaii's Pan-STARRS1 telescope, funded by NASA'sNear-Earth Object Observations(NEOO) Program, which finds and tracks asteroids and comets in Earth's neighborhood. NASA Planetary Defense Officer Lindley Johnson said, "We are fortunate that our sky survey telescope was looking in the right place at the right time to capture this historic moment. This serendipitous discovery is bonus science enabled by NASA's efforts to find, track and characterize near-Earth objects that could potentially pose a threat to our planet."

Preliminary orbital calculations suggest that the object came from the approximate direction of the bright star Vega, in the northern constellation of Lyra. However, it took so long for the interstellar object to make the journey - even at the speed of about 59,000 miles per hour (26.4 kilometers per second) -- that Vega was not near that position when the asteroid was there about 300,000 years ago.

While originally classified as a comet, observations from ESO and elsewhere revealed no signs of cometary activity after it slingshotted past the Sun on Sept. 9 at a blistering speed of 196,000 miles per hour (87.3 kilometers per second).

The object has since beenreclassified as interstellar asteroid1I/2017 U1 by the International Astronomical Union (IAU), which is responsible for granting official names to bodies in the solar system and beyond. In addition to the technical name, the Pan-STARRS team dubbed it 'Oumuamua (pronounced oh MOO-uh MOO-uh), which is Hawaiian for "a messenger from afar arriving first."

Astronomers estimate that an interstellar asteroid similar to 'Oumuamua passes through the inner solar system about once per year, but they are faint and hard to spot and have been missed until now. It is only recently that survey telescopes, such as Pan-STARRS, are powerful enough to have a chance to discover them.

"What a fascinating discovery this is!" said Paul Chodas, manager of the Center for Near-Earth Object Studies at NASA's Jet Propulsion Laboratory, Pasadena, California. "It's a strange visitor from a faraway star system, shaped like nothing we've ever seen in our own solar system neighborhood."

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NASA Astronaut Available for Interviews Before Space Station Mission

NASA astronaut Scott Tingle will be available at 6 a.m. EST Friday, Dec. 1 for live satellite interviews one last time prior to his upcoming launch to the International Space Station Dec. 17, on what will be his first mission in space.

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Recurring Martian Streaks: Flowing Sand, Not Water?

Fast Facts:

› Seasonal dark streaks on Mars have been described as possible signs of flowing water; a new study shows they are a better fit to dry flow processes.

› The steepness of more than 150 of these features was assessed with a telescopic camera on a NASA Mars orbiter.

› The findings add to evidence that these environments may be too dry for microbes to thrive, despite the presence of water in hydrated salts.

› How seasonal warming triggers these streaks is still a puzzle, and water may be involved.

Dark features on Mars previously considered evidence for subsurface flowing of water are interpreted by new research as granular flows, where grains of sand and dust slip downhill to make dark streaks, rather than the ground being darkened by seeping water.

Continuing examination of these still-perplexing seasonal dark streaks with a powerful camera on NASA's Mars Reconnaissance Orbiter (MRO) shows they exist only on slopes steep enough for dry grains to descend the way they do on faces of active dunes.

The findings published today in Nature Geoscience argue against the presence of enough liquid water for microbial life to thrive at these sites. However, exactly how these numerous flows begin and gradually grow has not yet been explained. Authors of the report propose possibilities that include involvement of small amounts of water, indicated by detection of hydrated salts observed at some of the flow sites.

These features have evoked fascination and controversy since their 2011 discovery, as possible markers for unexpected liquid water or brine on an otherwise dry planet. They are dark streaks that extend gradually downhill in warm seasons, then fade away in winter and reappear the next year. On Earth, only seeping water is known to have these behaviors, but how they form in the dry Martian environment remains unclear.

Many thousands of these Martian features, collectively called "recurring slope lineae" or RSL, have been identified in more than 50 rocky-slope areas, from the equator to about halfway to the poles.

"We've thought of RSL as possible liquid water flows, but the slopes are more like what we expect for dry sand," said Colin Dundas of the U.S. Geological Survey's Astrogeology Science Center in Flagstaff, Arizona. "This new understanding of RSL supports other evidence that shows that Mars today is very dry."

Dundas is lead author of the report, which is based on observations with the High Resolution Imaging Science Experiment (HiRISE) camera on MRO. The data include 3-D models of slope steepness using pairs of images for stereo information. Dundas and co-authors examined 151 RSL features at 10 sites.

The RSL are almost all restricted to slopes steeper than 27 degrees. Each flow ends on a slope that matches the dynamic "angle of repose" seen in the slumping dry sand of dunes on Mars and Earth. A flow due to liquid water should readily extend to less steep slopes.

"The RSL don't flow onto shallower slopes, and the lengths of these are so closely correlated with the dynamic angle of repose, it can't be a coincidence," said HiRISE Principal Investigator Alfred McEwen at the University of Arizona, Tucson, a co-author of the new report.

The seasonal dark streaks have been thought of as possible evidence for biologically significant liquid water -- sufficient water for microbial life -- though explaining how so much liquid water could exist on the surface in Mars' modern environment would be challenging. A granular-flow explanation for RSL fits with the earlier understanding that the surface of modern Mars, exposed to a cold, thin atmosphere, lacks flowing water. A 2016 report also cast doubt on possible sources of underground water at RSL sites. Liquid water on today's Mars may be limited to traces of dissolved moisture from the atmosphere and thin films, which are challenging environments for life as we know it.

However, RSL remain puzzling. Traits with uncertain explanations include their gradual growth, their seasonal reappearance, their rapid fading when inactive, and the presence of hydrated salts, which have water molecules bound into their crystal stucture.

The new report describes possible connections between these traits and how RSL form. For example, salts can become hydrated by pulling water vapor from the atmosphere, and this process can form drops of salty water. Seasonal changes in hydration of salt-containing grains might result in some trigger mechanism for RSL grainflows, such as expansion, contraction, or release of some water. Darkening and fading might result from changes in hydration. If atmospheric water vapor is a trigger, then a question is why the RSL appear on some slopes but not others.

"RSL probably form by some mechanism that is unique to the environment of Mars," McEwen said, "so they represent an opportunity to learn about how Mars behaves, which is important for future surface exploration."

"Full understanding of RSL is likely to depend upon on-site investigation of these features," said MRO Project Scientist Rich Zurek of NASA's Jet Propulsion Laboratory, Pasadena, California. "While the new report suggests that RSL are not wet enough to favor microbial life, it is likely that on-site investigation of these sites will still require special procedures to guard against introducing microbes from Earth, at least until they are definitively characterized. In particular, a full explanation of how these enigmatic features darken and fade still eludes us. Remote sensing at different times of day could provide important clues."

The University of Arizona operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colorado. JPL, a division of Caltech in Pasadena, California, manages the MRO Project for the NASA Science Mission Directorate in Washington. Lockheed Martin Space Systems of Denver built the orbiter and supports its operations.

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Guy Webster

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NASA Launches NOAA Weather Satellite Aboard United Launch Alliance Rocket to Improve Forecasts

NASA has successfully launched for the National Oceanic and Atmospheric Administration (NOAA) the first in a series of four highly advanced polar-orbiting satellites, equipped with next-generation technology and designed to improve the accuracy of U.S. weather forecasts out to seven days.

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New NASA Insights into the Secret Lives of Plants

NASA Selects Instrument for Future International Mission to Martian Moons

NASA has selected a science instrument for an upcoming Japan-led sample return mission to the moons of Mars planned for launch in 2024.

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NASA Survey Technique Estimates Congo Forest's Carbon

The equivalent of 85 billion tons of carbon dioxide -- a huge amount equal to three-quarters of the carbon stored in forests across the contiguous United States -- is locked in the living vegetation of one African country that holds much of the second largest tropical rainforest in the world, according to new research.

The study conducted by NASA, UCLA and the World Wide Fund for Nature-Germany produced the first high-resolution map of the amount and distribution of carbon stored in the Democratic Republic of Congo (DRC). DRC is the largest country in the Congo Basin and home to a massive and largely inaccessible rainforest that is Earth's second largest reservoir of carbon in vegetation, second only to the Amazon Basin rainforest. The DRC's forests cover an area four times the size of California.

The DRC carbon stock estimates are based on very fine-scale three-dimensional measurements of forest structure that provide, for the first time, data for one of the most diverse tropical forests on Earth. The measurements will help scientists understand the role of this forest in the global carbon cycle and how variations in climate may influence their carbon stock and function.

"We learned that the distribution of carbon in the above-ground biomass of the more than 150 million hectares (about 371 million acres) of forest in the DRC is extremely variable and diverse because of the region's climate, soil types, and a long history of human presence," said Sassan Saatchi, a senior researcher at NASA's Jet Propulsion Laboratory in Pasadena, California, who led the research team. "You cannot think of the Congo rainforest as this big green carpet anymore. We encountered a large variety of tree sizes and densities across the DRC, producing extremely complex regional patterns of carbon stored in the forest."

Traditionally, inventories of forest carbon and biomass are done by researchers who hike into the forest and set up plots on the ground that attempt to capture the full range of terrain. These data are then catalogued, measured and revisited in the future to see how they've changed. The Congo Basin forests, however, span five countries, and many areas are difficult to access due to the lack of infrastructure and rough terrain, which doesn't allow for comprehensive ground measurements of the forest carbon. To observe the forests, the research team took to both air and space.

Using the same forestry techniques to establish inventory plots on the ground, the research team contracted a local African company to fly an airplane outfitted with a commercial Light Detection and Ranging (LIDAR) instrument over 216 locations covering more than 2.5 million acres (half a million hectares) of tropical forest. At each location, the LIDAR captured the height, canopy profile, and outline of treetop canopies with data points 20 inches (50 centimeters) apart, from which they derived the forest structure and carbon estimate. These data were paired with data from NASA's Shuttle Radar Topography Mission, which provided the slopes and curves of the ground surface itself; Japan Aerospace Exploration Agency Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar (PALSAR) data; and U.S. Geological Survey-NASA Landsat vegetation observations. The combined data sets were scaled up to produce a map of the entire above-ground forest carbon stocks for each 12,000-square-yard (1-hectare) land unit.

Conserving tropical forests like the Congo is a high priority for the United Nations in its efforts to defray the effects of climate change. The U.N. has a policy initiative known as Reduce Emissions from Deforestation and Degradation (REDD+) in nations with large forests like the DRC. The new findings and research methods, conducted in partnership with scientists and the DRC government, are the first step for DRC to establish a baseline assessment of its carbon stocks and a system for future forest monitoring required to participate in REDD+ and be eligible for compensation for preserving the forests.

Saatchi says preserving forests is probably the most immediate mechanism we have to mitigate carbon dioxide accumulating in the atmosphere. A quarter of the entire amount of carbon that goes into the atmosphere globally is absorbed by Earth's vegetation, so protecting and possibly increasing the amount of carbon stored in forests could have significant benefits, such as mitigating climate change and preserving biodiversity and water quality.

"The DRC national carbon map is a truly significant contribution to DRC's future sustainable development," said co-author Aurélie Shapiro at World Wide Fund for Nature-Germany in Berlin. "This innovative product demonstrates with unprecedented accuracy the important role of Congolese forests in mitigating climate change, which is facilitating investments into emissions reductions programs."

To estimate the carbon stored above ground in DRC forests, the research team developed data sets for tree height and tree cover, which vary from one end of the DRC to the other. This information is also extremely helpful to conservationists interested in quantifying the health of habitats for gorillas and other at-risk animals, said Shapiro.

The new results will help test and validate the capabilities of two upcoming NASA missions: the NASA-Indian Space Research Organization Synthetic Aperture Radar, or NISAR, mission, managed by JPL; and the LIDAR observations from the Global Ecosystem Dynamics Investigation, or GEDI, mission, managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland. GEDI will mount a space-based LIDAR on the International Space Station to produce high-resolution 3-D imagery of Earth's forests.

The study is published Nov. 8 in Scientific Reports, a Nature publication. The paper is at:

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Tennessee Students to Speak with NASA Astronauts on International Space Station

Students at Southside Elementary School in Lebanon, Tennessee, will have the opportunity to speak with NASA astronauts living, working and doing research aboard the International Space Station at 10:05 a.m. EST Monday, Nov. 20.

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Lava or Not, Exoplanet 55 Cancri e Likely to have Atmosphere

Twice as big as Earth, the super-Earth 55 Cancri e was thought to have lava flows on its surface. The planet is so close to its star, the same side of the planet always faces the star, such that the planet has permanent day and night sides. Based on a 2016 study using data from NASA's Spitzer Space Telescope, scientists speculated that lava would flow freely in lakes on the starlit side and become hardened on the face of perpetual darkness. The lava on the dayside would reflect radiation from the star, contributing to the overall observed temperature of the planet.

Now, a deeper analysis of the same Spitzer data finds this planet likely has an atmosphere whose ingredients could be similar to those of Earth's atmosphere, but thicker. Lava lakes directly exposed to space without an atmosphere would create local hot spots of high temperatures, so they are not the best explanation for the Spitzer observations, scientists said.

"If there is lava on this planet, it would need to cover the entire surface," said Renyu Hu, astronomer at NASA's Jet Propulsion Laboratory, Pasadena, California, and co-author of a study published in The Astronomical Journal. "But the lava would be hidden from our view by the thick atmosphere."

Using an improved model of how energy would flow throughout the planet and radiate back into space, researchers find that the night side of the planet is not as cool as previously thought. The "cold" side is still quite toasty by Earthly standards, with an average of 2,400 to 2,600 degrees Fahrenheit (1,300 to 1,400 Celsius), and the hot side averages 4,200 degrees Fahrenheit (2,300 Celsius). The difference between the hot and cold sides would need to be more extreme if there were no atmosphere.

"Scientists have been debating whether this planet has an atmosphere like Earth and Venus, or just a rocky core and no atmosphere, like Mercury. The case for an atmosphere is now stronger than ever," Hu said.

Researchers say the atmosphere of this mysterious planet could contain nitrogen, water and even oxygen -- molecules found in our atmosphere, too -- but with much higher temperatures throughout. The density of the planet is also similar to Earth, suggesting that it, too, is rocky. The intense heat from the host star would be far too great to support life, however, and could not maintain liquid water.

Hu developed a method of studying exoplanet atmospheres and surfaces, and had previously only applied it to sizzling, giant gaseous planets called hot Jupiters. Isabel Angelo, first author of the study and a senior at the University of California, Berkeley, worked on the study as part of her internship at JPL and adapted Hu's model to 55 Cancri e.

In a seminar, she heard about 55 Cancri e as a potentially carbon-rich planet, so high in temperature and pressure that its interior could contain a large amount of diamond.

"It's an exoplanet whose nature is pretty contested, which I thought was exciting," Angelo said.

Spitzer observed 55 Cancri e between June 15 and July 15, 2013, using a camera specially designed for viewing infrared light, which is invisible to human eyes. Infrared light is an indicator of heat energy. By comparing changes in brightness Spitzer observed to the energy flow models, researchers realized an atmosphere with volatile materials could best explain the temperatures.

There are many open questions about 55 Cancri e, especially: Why has the atmosphere not been stripped away from the planet, given the perilous radiation environment of the star?

"Understanding this planet will help us address larger questions about the evolution of rocky planets," Hu said.

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

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NASA’s Fiscal Year 2017 Financial Audit Result

NASA has received an unmodified audit opinion on its Fiscal Year 2017 (FY 2017) financial statements, making this the seventh consecutive year of "clean" opinions.

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Our Living Planet Shapes the Search for Life Beyond Earth

As a young scientist, Tony del Genio of NASA's Goddard Institute for Space Studies in New York City met Clyde Tombaugh, the discoverer of Pluto.

"I thought, 'Wow, this is a one-time opportunity,'" del Genio said. "I'll never meet anyone else who found a planet."

That prediction was spectacularly wrong. In 1992, two scientists discovered the first planet around another star, or exoplanet, and since then more people have found planets than throughout all of Earth's preceding history. As of this month, scientists have confirmed more than 3,500 exoplanets in more than 2,700 star systems. Del Genio has met many of these new planet finders.

Del Genio is now co-lead of a NASA interdisciplinary initiative to search for life on other worlds. This new position as the lead of this project may seem odd to those who know him professionally. Why? He has dedicated decades to studying Earth, not searching for life elsewhere.

We know of only one living planet: our own. But we know it very well. As we move to the next stage in the search for alien life, the effort will require the expertise of planetary scientists, heliophysicists and astrophysicists. However, the knowledge and tools NASA has developed to study life on Earth will also be one of the greatest assets to the quest.

Habitable Worlds

There are two main questions in the search for life: With so many places to look, how can we focus in on the places most likely to harbor life? What are the unmistakable signs of life -- even if it comes in a form we don't fully understand?

"Before we go looking for life, we're trying to figure out what kinds of planets could have a climate that's conducive to life," del Genio said. "We're using the same climate models that we use to project 21st century climate change on Earth to do simulations of specific exoplanets that have been discovered, and hypothetical ones."

Del Genio recognizes that life may well exist in forms and places so bizarre that it might be substantially different from Earth. But in this early phase of the search, "We have to go with the kind of life we know," he said.

Further, we should make sure we use the detailed knowledge of Earth. In particular, we should make sure of our discoveries on life in various environments on Earth, our knowledge of how our planet and its life have affected each other over Earth history, and our satellite observations of Earth's climate.

Above all else, that means liquid water. Every cell we know of -- even bacteria around deep-sea vents that exist without sunlight -- requires water.

Life in the Ocean

Research scientist Morgan Cable of NASA's Jet Propulsion Laboratory in Pasadena, California, is looking within the solar system for locations that have the potential to support liquid water. Some of the icy moons around Saturn and Jupiter have oceans below the ice crust. These oceans were formed by tidal heating, that is, warming of the ice caused by friction between the surface ice and the core as a result of the gravitational interaction between the planet and the moon.

"We thought Enceladus was just boring and cold until the Cassini mission discovered a liquid water subsurface ocean," said Cable. The water is spraying into space, and the Cassini mission found hints in the chemical composition of the spray that the ocean chemistry is affected by interactions between heated water and rocks at the seafloor. The Galileo and Voyager missions provided evidence that Europa also has a liquid water ocean under an icy crust. Observations revealed a jumbled terrain that could be the result of ice melting and reforming.

As missions to these moons are being developed, scientists are using Earth as a testbed. Just as prototypes for NASA's Mars rovers made their trial runs on Earth's deserts, researchers are testing both hypotheses and technology on our oceans and extreme environments.

Cable gave the example of satellite observations of Arctic and Antarctic ice fields, which are informing the planning for a Europa mission. The Earth observations help researchers find ways to date the origin of jumbled ice. "When we visit Europa, we want to go to very young places, where material from that ocean is being expressed on the surface," she said. "Anywhere like that, the chances of finding evidence of life goes up -- if they're there."

Water in Space

For any star, it's possible to calculate the range of distances where orbiting planets could have liquid water on the surface. This is called the star's habitable zone.

Astronomers have already located some habitable-zone planets, and research scientist Andrew Rushby, of NASA Ames Research Center, in Moffett Field, California, is studying ways to refine the search. Location alone isn't enough. "An alien would spot three planets in our solar system in the habitable zone [Earth, Mars and Venus]," Rushby said, "but we know that 67 percent of those planets are not very habitable." He recently developed a simplified model of Earth's carbon cycle and combined it with other tools to study which planets in the habitable zone would be the best targets to look at for life, considering probable tectonic activity and water cycles. He found that larger rocky planets are more likely than smaller ones to have surface temperatures where liquid water could exist, given the same amount of light from the star.

Renyu Hu, of JPL, refined the search for habitable planets in a different way, looking for the signature of a rocky planet. Basic physics tells us that smaller planets must be rocky and larger ones gaseous, but for planets ranging from Earth-sized to about twice that radius, astronomers can't tell a large rocky planet from a small gaseous planet. Hu pioneered a method to detect surface minerals on bare-rock exoplanets and defined the atmospheric chemical signature of volcanic activity, which wouldn't occur on a gas planet.

Vital Signs

When scientists are evaluating a possible habitable planet, "life has to be the hypothesis of last resort," Cable said. "You must eliminate all other explanations." Identifying possible false positives for the signal of life is an ongoing area of research in the exoplanet community. For example, the oxygen in Earth's atmosphere comes from living things, but oxygen can also be produced by inorganic chemical reactions.

Shawn Domagal-Goldman, of NASA's Goddard Space Flight Center in Greenbelt, Maryland, looks for unmistakable, chemical signs of life, or biosignatures. One biosignature may be finding two or more molecules in an atmosphere that shouldn't be there at the same time. He uses this analogy: If you walked into a college dorm room and found three students and a pizza, you could conclude that the pizza had recently arrived, because college students quickly consume pizza. Oxygen "consumes" methane by breaking it down in various chemical reactions. Without inputs of methane from life on Earth's surface, our atmosphere would become totally depleted of methane within a few decades.

Earth as Exoplanet

When humans start collecting direct images of exoplanets, even the closest one will appear as a handful of pixels in the detector - something like the famous "blue dot" image of Earth from Saturn. What can we learn about planetary life from a single dot?

Stephen Kane of the University of California, Riverside, has come up with a way to answer that question using NASA's Earth Polychromatic Imaging camera on the National Oceanic and Atmospheric Administration's Deep Space Climate Observatory (DSCOVR). These high-resolution images -- 2,000 x 2,000 pixels - document Earth's global weather patterns and other climate-related phenomena. "I'm taking these glorious pictures and collapsing them down to a single pixel or handful of pixels," Kane explained. He runs the light through a noise filter that attempts to simulate the interference expected from an exoplanet mission.

DSCOVR takes a picture every half hour, and it's been in orbit for two years. Its more than 30,000 images are by far the longest continuous record of Earth from space in existence. By observing how the brightness of Earth changes when mostly land is in view compared with mostly water, Kane has been able to reverse-engineer Earth's rotation rate -- something that has yet to be measured directly for exoplanets.

When Will We Find Life?

Every scientist involved in the search for life is convinced it's out there. Their opinions differ on when we'll find it.

"I think that in 20 years we will have found one candidate that might be it," says del Genio. Considering his experience with Tombaugh, he added, "But my track record for predicting the future is not so good."

Rushby, on the other hand, says, "It's been 20 years away for the last 50 years. I do think it's on the scale of decades. If I were a betting man, which I'm not, I'd go for Europa or Enceladus."

How soon we find a living exoplanet really depends on whether there's one relatively nearby, with the right orbit and size, and with biosignatures that we are able to recognize, Hu said. In other words, "There's always a factor of luck."

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NASA's Earth Science News Team

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NASA Expands Podcast Selections with New Science Series

“Gravity Assist,” a new NASA weekly podcast series launches Wednesday on NASA.gov and audio platforms SoundCloud and iTunes.

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NASA's Mars 2020 Mission Performs First Supersonic Parachute Test

Landing on Mars is difficult and not always successful. Well-designed advance testing helps. An ambitious NASA Mars rover mission set to launch in 2020 will rely on a special parachute to slow the spacecraft down as it enters the Martian atmosphere at over 12,000 mph (5.4 kilometers per second). Preparations for this mission have provided, for the first time, dramatic video of the parachute opening at supersonic speed.

The Mars 2020 mission will seek signs of ancient Martian life by investigating evidence in place and by caching drilled samples of Martian rocks for potential future return to Earth. The mission's parachute-testing series, the Advanced Supersonic Parachute Inflation Research Experiment, or ASPIRE, began with a rocket launch and upper-atmosphere flight last month from the NASA Goddard Space Flight Center's Wallops Flight Facility in Wallops Island, Virginia.

› DOWNLOAD VIDEO NASA's Mars 2020 Supersonic Parachute: Test Flight #1

"It is quite a ride," said Ian Clark, the test's technical lead from NASA's Jet Propulsion Laboratory in Pasadena, California. "The imagery of our first parachute inflation is almost as breathtaking to behold as it is scientifically significant. For the first time, we get to see what it would look like to be in a spacecraft hurtling towards the Red Planet, unfurling its parachute."

A 58-foot-tall (17.7-meter) Black Brant IX sounding rocket launched from Wallops on Oct. 4 for this evaluation of the ASPIRE payload performance. The payload is a bullet-nosed, cylindrical structure holding a supersonic parachute, the parachute's deployment mechanism, and the test's high-definition instrumentation -- including cameras -- to record data.

The rocket carried the payload as high as about 32 miles (51 kilometers). Forty-two seconds later, at an altitude of 26 miles (42 kilometers) and a velocity of 1.8 times the speed of sound, the test conditions were met and the Mars parachute successfully deployed. Thirty-five minutes after launch, ASPIRE splashed down in the Atlantic Ocean about 34 miles (54 kilometers) southeast of Wallops Island.

"Everything went according to plan or better than planned," said Clark. "We not only proved that we could get our payload to the correct altitude and velocity conditions to best mimic a parachute deployment in the Martian atmosphere, but as an added bonus, we got to see our parachute in action as well."

The parachute tested during this first flight was almost an exact copy of the parachute used to land NASA's Mars Science Laboratory successfully on the Red Planet in 2012. Future tests will evaluate the performance of a strengthened parachute that could also be used in future Mars missions. The Mars 2020 team will use data from these tests to finalize the design for its mission.

The next ASPIRE test is planned for February 2018.

The Mars 2020 project's parachute-testing series, ASPIRE, is managed by the Jet Propulsion Laboratory, with support from NASA's Langley Research Center, Hampton, Virginia, and NASA's Ames Research Center, Mountain View, California, for NASA's Space Science Mission Directorate. NASA's Sounding Rocket Program is based at the agency's Wallops Flight Facility. Orbital ATK provides mission planning, engineering services and field operations through the NASA Sounding Rocket Operations Contract. NASA's Heliophysics Division manages the sounding-rocket program for the agency.

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Listening for Gravitational Waves Using Pulsars

One of the most spectacular achievements in physics so far this century has been the observation of gravitational waves, ripples in space-time that result from masses accelerating in space. So far, there have been five detections of gravitational waves, thanks to the Laser Interferometer Gravitational-Wave Observatory (LIGO) and, more recently, the European Virgo gravitational-wave detector. Using these facilities, scientists have been able to pin down the extremely subtle signals from relatively small black holes and, as of October, neutron stars.

But there are merging objects far larger whose gravitational wave signals have not yet been detected: supermassive black holes, more than 100 million times more massive than our Sun. Most large galaxies have a central supermassive black hole. When galaxies collide, their central black holes tend to spiral toward each other, releasing gravitational waves in their cosmic dance. Much as a large animal like a lion produces a deeper roar than a tiny mouse's squeak, merging supermassive black holes create lower-frequency gravitational waves than the relatively small black holes LIGO and similar ground-based experiments can detect.

"Observing low-frequency gravitational waves would be akin to being able to hear bass singers, not just sopranos," said Joseph Lazio, chief scientist for NASA's Deep Space Network, based at NASA's Jet Propulsion Laboratory, Pasadena, California, and co-author of a new study in Nature Astronomy.

To explore this uncharted area of gravitational wave science, researchers look not to human-made machines, but to a natural experiment in the sky called a pulsar timing array. Pulsars are dense remnants of dead stars that regularly emit beams of radio waves, which is why some call them "cosmic lighthouses." Because their rapid pulse of radio emission is so predictable, a large array of well-understood pulsars can be used to measure extremely subtle abnormalities, such as gravitational waves. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav), a Physics Frontier Center of the National Science Foundation, is one of the leading groups of researchers using pulsars to search for gravitational waves.

The new Nature Astronomy study concerns supermassive black hole binaries -- systems of two of these cosmic monsters. For the first time, researchers surveyed the local universe for galaxies likely to host these binaries, then predicted which black hole pairs are the likeliest to merge and be detected while doing so. The study also estimates how long it will take to detect one of these mergers.

"By expanding our pulsar timing array over the next 10 years or so, there is a high likelihood of detecting gravitational waves from at least one supermassive black hole binary," said Chiara Mingarelli, lead study author, who worked on this research as a Marie Curie postdoctoral fellow at Caltech and JPL, and is now at the Flatiron Institute in New York.

Mingarelli and colleagues used data from the 2 Micron All-Sky Survey (2MASS), which surveyed the sky from 1997 to 2001, and galaxy merger rates from the Illustris simulation project, an endeavor to make large-scale cosmological simulations. In their sample of about 5,000 galaxies, scientists found that about 90 would have supermassive black holes most likely to merge with another black hole.

While LIGO and similar experiments detect objects in the final seconds before they merge, pulsar timing arrays are sensitive to gravitational wave signals from supermassive black holes that are spiraling toward each other and will not combine for millions of years. That's because galaxies merge hundreds of millions of years before the central black holes they host combine to make one giant supermassive black hole.

Researchers also found that while bigger galaxies have bigger black holes and produce stronger gravitational waves when they combine, these mergers also happen fast, shortening the time period for detection. For example, black holes merging in the large galaxy M87 would have a 4-million-year window of detection. By contrast, in the smaller Sombrero Galaxy, black holes mergers typically take about 160 million years, offering more opportunities for pulsar timing arrays to detect gravitational waves from them.

Black hole mergers generate gravitational waves because, as they orbit each other, their gravity distorts the fabric of space-time, sending ripples outward in all directions at the speed of light. These distortions actually shift the position of Earth and the pulsars ever so slightly, resulting in a characteristic and detectable signal from the array of celestial lighthouses.

"A difference between when the pulsar signals should arrive, and when they do arrive, can signal a gravitational wave,"Mingarelli said. "And since the pulsars we study are about 3,000 light-years away, they act as a galactic-scale gravitational-wave detector."

Because all supermassive black holes are so distant, gravitational waves, which travel at the speed of light, take a long time to arrive at Earth. This study looked at supermassive black holes within about 700 million light-years, meaning waves from a merger between any two of them would take up to that long to be detected here by scientists.By comparison, the oldest animal life on Earth -- algae -- is thought to have arisen about 650 million years ago.

Many open questions remain about how galaxies merge and what will happen when the Milky Way approaches Andromeda, the nearby galaxy that will collide with ours in about 4 billion years.

"Detecting gravitational waves from billion-solar-mass black hole mergers will help unlock some of the most persistent puzzles in galaxy formation," said Leonidas Moustakas, a JPL research scientist who wrote an accompanying "News and Views" article in the journal.

2MASS was funded by NASA's Office of Space Science, the National Science Foundation, the U.S. Naval Observatory and the University of Massachusetts. JPL managed the program for NASA's Office of Space Science, Washington. Data was processed at IPAC at Caltech in Pasadena, California.

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Elizabeth Landau

Jet Propulsion Laboratory, Pasadena, Calif.

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2017-293

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NASA Space Station Cargo Launches Aboard Orbital ATK Mission

The International Space Station will receive about 7,400 pounds of cargo, including new science and technology investigations, following the successful launch of Orbital ATK’s Cygnus spacecraft from NASA’s Wallops Flight Facility in Virginia Sunday.

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Dawn Explores Ceres' Interior Evolution

NASA Sets Media Coverage of Rescheduled NOAA Weather Satellite Launch

The Joint Polar Satellite System-1 (JPSS-1) satellite, the first in a new series of four highly advanced National Oceanic and Atmospheric Administration (NOAA) polar-orbiting satellites, now is scheduled to launch on Tuesday, Nov. 14, from Vandenberg Air Force Base, California.

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NASA Pays Tribute to Early Space Pioneer Richard Gordon

The following is a statement from acting NASA Administrator Robert Lightfoot on the passing of former NASA astronaut Richard Gordon:

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Hot News from the Antarctic Underground

Study Bolsters Theory of Heat Source Under West Antarctica

A new NASA study adds evidence that a geothermal heat source called a mantle plume lies deep below Antarctica's Marie Byrd Land, explaining some of the melting that creates lakes and rivers under the ice sheet. Although the heat source isn't a new or increasing threat to the West Antarctic ice sheet, it may help explain why the ice sheet collapsed rapidly in an earlier era of rapid climate change, and why it is so unstable today.

The stability of an ice sheet is closely related to how much water lubricates it from below, allowing glaciers to slide more easily. Understanding the sources and future of the meltwater under West Antarctica is important for estimating the rate at which ice may be lost to the ocean in the future.

Antarctica's bedrock is laced with rivers and lakes, the largest of which is the size of Lake Erie. Many lakes fill and drain rapidly, forcing the ice surface thousands of feet above them to rise and fall by as much as 20 feet (6 meters). The motion allows scientists to estimate where and how much water must exist at the base.

Some 30 years ago, a scientist at the University of Colorado Denver suggested that heat from a mantle plume under Marie Byrd Land might explain regional volcanic activity and a topographic dome feature. Very recent seismic imaging has supported this concept. When Hélène Seroussi of NASA's Jet Propulsion Laboratory in Pasadena, California, first heard the idea, however, "I thought it was crazy," she said. "I didn't see how we could have that amount of heat and still have ice on top of it."

With few direct measurements existing from under the ice, Seroussi and Erik Ivins of JPL concluded the best way to study the mantle plume idea was by numerical modeling. They used the Ice Sheet System Model (ISSM), a numerical depiction of the physics of ice sheets developed by scientists at JPL and the University of California, Irvine. Seroussi enhanced the ISSM to capture natural sources of heating and heat transport from freezing, melting and liquid water; friction; and other processes.

To assure the model was realistic, the scientists drew on observations of changes in the altitude of the ice sheet surface made by NASA's IceSat satellite and airborne Operation IceBridge campaign. "These place a powerful constraint on allowable melt rates -- the very thing we wanted to predict," Ivins said. Since the location and size of the possible mantle plume were unknown, they tested a full range of what was physically possible for multiple parameters, producing dozens of different simulations.

They found that the flux of energy from the mantle plume must be no more than 150 milliwatts per square meter. For comparison, in U.S. regions with no volcanic activity, the heat flux from Earth's mantle is 40 to 60 milliwatts. Under Yellowstone National Park -- a well-known geothermal hot spot -- the heat from below is about 200 milliwatts per square meter averaged over the entire park, though individual geothermal features such as geysers are much hotter.

Seroussi and Ivins' simulations using a heat flow higher than 150 milliwatts per square meter showed too much melting to be compatible with the space-based data, except in one location: an area inland of the Ross Sea known for intense flows of water. This region required a heat flow of at least 150-180 milliwatts per square meter to agree with the observations. However, seismic imaging has shown that mantle heat in this region may reach the ice sheet through a rift, that is, a fracture in Earth's crust such as appears in Africa's Great Rift Valley.

Mantle plumes are thought to be narrow streams of hot rock rising through Earth's mantle and spreading out like a mushroom cap under the crust. The buoyancy of the material, some of it molten, causes the crust to bulge upward. The theory of mantle plumes was proposed in the 1970s to explain geothermal activity that occurs far from the boundary of a tectonic plate, such as Hawaii and Yellowstone.

The Marie Byrd Land mantle plume formed 50 to 110 million years ago, long before the West Antarctic ice sheet came into existence. At the end of the last ice age around 11,000 years ago, the ice sheet went through a period of rapid, sustained ice loss when changes in global weather patterns and rising sea levels pushed warm water closer to the ice sheet -- just as is happening today. Seroussi and Ivins suggest the mantle plume could facilitate this kind of rapid loss.

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Alan Buis

Jet Propulsion Laboratory, Pasadena, California

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Written by Carol Rasmussen

NASA's Earth Science News Team

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NASA TV Coverage Set for Next Resupply Mission to International Space Station

NASA commercial cargo provider Orbital ATK is scheduled to launch its eighth mission to the International Space Station at 7:37 a.m. EST Saturday, Nov. 11 NASA’s Wallops Flight Facility in Virginia.

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Powering Saturn's Active Ocean Moon

Heat from friction could power hydrothermal activity on Saturn's moon Enceladus for billions of years if the moon has a highly porous core, according to a new modeling study by European and U.S. researchers working on NASA's Cassini mission.

The study, published today in the journal Nature Astronomy, helps resolve a question scientists have grappled with for a decade:Where does the energy to power the extraordinary geologic activity on Enceladus come from?

Cassini found that Enceladus sprays towering, geyser-like jets of water vapor and icy particles, including simple organics, from warm fractures near its south pole. Additional investigation revealed the moon has a global ocean beneath its icy crust,from which the jets are venting into space. Multiple lines of evidence from Cassini indicate that hydrothermal activity -- hot water interacting chemically with rock -- is taking place on the seafloor.

One of those lines was the detection of tiny rock grains inferred to be the product of hydrothermal chemistry taking place at temperatures of at least 194 degrees Fahrenheit (90 degrees Celsius). The amount of energy required to produce these temperatures is more than scientists think could be provided by decay of radioactive elements in the interior.

"Where Enceladus gets the sustained power to remain active has always been a bit of a mystery, but we've now considered in greater detail how the structure and composition of the moon's rocky core could play a key role in generating the necessary energy," said the study's lead author, Gaël Choblet from the University of Nantes in France.

Choblet and co-authors found that a loose, rocky core with 20 to 30 percent empty space would do the trick. Their simulations show that as Enceladus orbits Saturn, rocks in the porous core flex and rub together, generating heat. The loose interior also allows water from the ocean to percolate deep down, where it heats up, then rises, interacting chemically with the rocks. The models show this activity should be at a maximum at the moon's poles. Plumes of the warm, mineral-laden water gush from the seafloor and travel upward, thinning the moon's ice shell from beneath to only half a mile to 3 miles (1 to 5 kilometers) at the south pole. (The average global thickness of the ice is thought to be about 12 to 16 miles, or 20 to 25 kilometers.) And this same water is then expelled into space through fractures in the ice.

The study is the first to explain several key characteristics of Enceladus observed by Cassini: the global ocean, internal heating, thinner ice at the south pole, and hydrothermal activity. It doesn't explain why the north and south poles are so different though. Unlike the tortured, geologically fresh landscape of the south, Enceladus' northern extremes are heavily cratered and ancient. The authors note that if the ice shell was slightly thinner in the south to begin with, it would lead to runaway heating there over time.

The researchers estimate that, over time (between 25 and 250 million years), the entire volume of Enceladus' ocean passes through the moon's core. This is estimated to be an amount of water equal to two percent of the volume of Earth's oceans.

Flexing of Enceladus' icy crust due to the tidal pull of Saturn had previously been considered as a heat source, but models showed this would not produce enough sustained power. The ocean in Enceladus would have frozen within 30 million years. Although past studies modeled how tidal friction could generate heat in the moon's core, they made simpler assumptions or simulated the moon in only two dimensions. The new study ramped up the complexity of the model and simulated Enceladus in 3-D.

Although the Cassini science team had suspected for years that a porous core might play an important role in the mystery of Enceladus' warm interior, this study brings together several more recent lines of evidence in a very elegant way, according to NASA's Cassini Project Scientist Linda Spilker at theagency's Jet Propulsion Laboratory in Pasadena, California. "This powerful research makes use of newer details -- namely that the ocean is global and has hydrothermal activity -- that we just didn't have until the past couple of years. It's an insight that the mission needed time to build, one discovery upon another," she said.

Launched in 1997, the Cassini spacecraft orbited Saturn from 2004 to 2017. Cassini made numerous dramatic discoveries, including the surprising activity on Enceladus and liquid methane seas on Saturn's largest moon, Titan. Cassini ended its journey with a dramatic plunge into Saturn's atmosphere on Sept. 15, 2017, returning unique science data until it lost contact with Earth.

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.

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Preston Dyches

Jet Propulsion Laboratory, Pasadena, Calif.

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2017-290

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Virginia Students to Speak with NASA Astronauts on Space Station

NASA's Joe Acaba, Mark Vande Hei, and Randy Bresnik, during 52S Arrival,

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Astronomers Complete First International Asteroid Tracking Exercise

An international team of astronomers led by NASA scientists successfully completed the first global exercise using a real asteroid to test global response capabilities.

Planning for the so-called "TC4 Observation Campaign" started in April, under the sponsorship of NASA's Planetary Defense Coordination Office. The exercise commenced in earnest in late July, when the European Southern Observatory's Very Large Telescope recovered the asteroid. The finale was a close approach to Earth in mid-October. The goal: to recover, track and characterize a real asteroid as a potential impactor -- and to test the International Asteroid Warning Network for hazardous asteroid observations, modeling, prediction and communication.

The target of the exercise was asteroid 2012 TC4 -- a small asteroid originally estimated to be between 30 and 100 feet (10 and 30 meters) in size, which was known to be on a very close approach to Earth. On Oct. 12, TC4 safely passed Earth at a distance of only about 27,200 miles (43,780 kilometers) above Earth's surface. In the months leading up to the flyby, astronomers from the U.S., Canada, Colombia, Germany, Israel, Italy, Japan, the Netherlands, Russia and South Africa all tracked TC4 from ground- and space-based telescopes to study its orbit, shape, rotation and composition.

"This campaign was an excellent test of a real threat case. I learned that in many cases we are already well-prepared; communication and the openness of the community was fantastic," said Detlef Koschny, co-manager of the near-Earth object (NEO) segment in the European Space Agency (ESA)'s Space Situational Awareness program. "I personally was not prepared enough for the high response from the public and media -- I was positively surprised by that! It shows that what we are doing is relevant."

"The 2012 TC4 campaign was a superb opportunity for researchers to demonstrate willingness and readiness to participate in serious international cooperation in addressing the potential hazard to Earth posed by NEOs," said Boris Shustov, science director for the Institute of Astronomy at the Russian Academy of Sciences. "I am pleased to see how scientists from different countries effectively and enthusiastically worked together toward a common goal, and that the Russian-Ukrainian observatory in Terskol was able to contribute to the effort." Shustov added, "In the future I am confident that such international observing campaigns will become common practice."

Using the observations collected during the campaign, scientists at NASA's Center for Near-Earth Object Studies (CNEOS) at the Jet Propulsion Laboratory in Pasadena, California were able to precisely calculate TC4's orbit, predict its flyby distance on Oct. 12, and look for any possibility of a future impact. "The high-quality observations from optical and radar telescopes have enabled us to rule out any future impacts between the Earth and 2012 TC4," said Davide Farnocchia from CNEOS, who led the orbit determination effort. "These observations also help us understand subtle effects such as solar radiation pressure that can gently nudge the orbit of small asteroids."

A network of optical telescopes also worked together to study how fast TC4 rotates. Given that TC4 is small, astronomers expected it to be rotating fast, but were surprised when they found that TC4 was not only spinning once every 12 minutes, it was also tumbling. "The rotational campaign was a true international effort. We had astronomers from several countries working together as one team to study TC4's tumbling behavior," said Eileen Ryan, director of the Magdalena Ridge Observatory. Her team tracked TC4 for about 2 months using the 7.9-foot (2.4-meter) telescope in Socorro, New Mexico.

The observations that revealed the shape and confirmed the composition of the asteroid came from astronomers using NASA's Goldstone Deep Space Network antenna in California and the National Radio Astronomy Observatory's 330-foot (100-meter) Green Bank Telescope in West Virginia. "TC4 is a very elongated asteroid that's about 50 feet (15 meters) long and roughly 25 feet (8 meters) wide," said Marina Brozovic, a member of the asteroid radar team at JPL.

Finding out what TC4 is made of turned out to be more challenging. Due to adverse weather conditions, traditional NASA assets studying asteroid composition -- such as the NASA Infrared Telescope Facility (IRTF) at the Mauna Kea Observatory in Hawaii -- were unable to narrow down what TC4 was made of: either dark, carbon-rich or bright igneous material.

"Radar has the ability to identify asteroids with surfaces made of highly reflective rocky or metallic materials," said Lance Benner, who led the radar observations at JPL. "We were able to show that radar scattering properties are consistent with a bright rocky surface, similar to a particular class of meteorites that reflect as much as 50 percent of the light falling on them."

In addition to the observation campaign, NASA used this exercise to test communications between the many observers and also to test internal U.S. government messaging and communications up through the executive branch and across government agencies, as it would during an actual predicted impact emergency.

"We demonstrated that we could organize a large, worldwide observing campaign on a short timeline, and communicate results efficiently," said Vishnu Reddy of the University of Arizona's Lunar and Planetary Laboratory in Tucson, who led the observation campaign. Michael Kelley, TC4 exercise lead at NASA Headquarters in Washington added, "We are much better prepared today to deal with the threat of a potentially hazardous asteroid than we were before the TC4 campaign."

NASA's Planetary Defense Coordination Office administers the Near-Earth Object Observations Program and is responsible for finding, tracking and characterizing potentially hazardous asteroids and comets coming near Earth, issuing warnings about possible impacts, and assisting coordination of U.S. government response planning, should there be an actual impact threat.

News Media Contact

DC Agle

Jet Propulsion Laboratory, Pasadena, Calif.

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Dwayne Brown / Laurie Cantillo

NASA Headquarters, Washington

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2017-289

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More Than 2.4 Million Names Are Going to Mars

Last month, NASA invited members of the public to send their names to Mars. And the public responded loud and clear.

More than 1.6 million people signed up to have their names etched on a microchip that will be carried on NASA's upcoming InSight mission, which launches in May of 2018.

NASA's Jet Propulsion Laboratory in Pasadena, California, reopened the opportunity after it proved successful in 2015. During that open call, nearly 827,000 names were collected for a microchip that now sits on top of the robotic InSight lander.

The grand total once a second microchip is added in early 2018 will be 2,429,807 names. Space enthusiasts who signed up this last round shared their downloadable "boarding passes" on social media, complete with the total number of flight miles they've collected by participating in engagement initiatives for other Mars missions.

InSight will be the first mission to look deep beneath the Martian surface, studying the planet's interior by listening for marsquakes. These quakes travel through geologic material at different speeds and give scientists a glimpse of the composition and structure of the planet's inside. The insights into how Mars formed will help us better understand how other rocky planets are created.

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Andrew Good

Jet Propulsion Laboratory, Pasadena, Calif.

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2017-288

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