NuSTAR Probes Black Hole Jet Mystery

Black holes are famous for being ravenous eaters, but they do not eat everything that falls toward them. A small portion of material gets shot back out in powerful jets of hot gas, called plasma, that can wreak havoc on their surroundings. Along the way, this plasma somehow gets energized enough to strongly radiate light, forming two bright columns along the black hole's axis of rotation. Scientists have long debated where and how this happens in the jet.

Astronomers have new clues to this mystery. Using NASA's NuSTAR space telescope and a fast camera called ULTRACAM on the William Herschel Observatory in La Palma, Spain, scientists have been able to measure the distance that particles in jets travel before they "turn on" and become bright sources of light. This distance is called the "acceleration zone." The study is published in the journal Nature Astronomy.

Scientists looked at two systems in the Milky Way called "X-ray binaries," each consisting of a black hole feeding off of a normal star. They studied these systems at different points during periods of outburst -- which is when the accretion disk -- a flat structure of material orbiting the black hole -- brightens because of material falling in.

One system, called V404 Cygni, had reached nearly peak brightness when scientists observed it in June 2015. At that time, it experienced the brightest outburst from an X-ray binary seen in the 21st century. The other, called GX 339-4,was less than 1 percent of its maximum expected brightness when it was observed. The star and black hole of GX 339-4 are much closer together than in the V404 Cygni system.

Despite their differences, the systems showed similar time delays - about one-tenth of a second -- between when NuSTAR first detected X-ray light and ULTRACAM detected flares in visible light slightly later. That delay is less than the blink of an eye, but significant for the physics of black hole jets.

"One possibility is that the physics of the jet is not determined by the size of the disc, but instead by the speed, temperature and other properties of particles at the jet's base," said Poshak Gandhi, lead author of the study and astronomer at the University of Southampton, United Kingdom.

The best theory scientists have to explain these results is that the X-ray light originates from material very close to the black hole. Strong magnetic fields propel some of this material to high speeds along the jet. This results in particles colliding near light-speed, energizing the plasma until it begins to emit the stream of optical radiation caught by ULTRACAM.

Where in the jet does this occur? The measured delay between optical and X-ray light explains this. By multiplying this amount of time by the speed of the particles, which is nearly the speed of light, scientists determine the maximum distance traveled.

This expanse of about 19,000 miles (30,000 kilometers) represents the inner acceleration zone in the jet, where plasma feels the strongest acceleration and "turns on" by emitting light. That's just under three times the diameter of Earth, but tiny in cosmic terms, especially considering the black hole in V404 Cygni weighs as much as 3 million Earths put together.

"Astronomers hope to refine models for jet powering mechanisms using the results of this study," said Daniel Stern, study co-author and astronomer based at NASA's Jet Propulsion Laboratory, Pasadena, California.

Making these measurements wasn't easy. X-ray telescopes in space and optical telescopes on the ground have to look at the X-ray binaries at exactly the same time during outbursts for scientists to calculate the tiny delay between the telescopes' detections. Such coordination requires complex planning between the observatory teams. In fact, coordination between NuSTAR and ULTRACAM was only possible for about an hour during the 2015 outburst, but that was enough to calculate the groundbreaking results about the acceleration zone.

The results also appear to connect with scientists' understanding of supermassive black holes, much bigger than the ones in this study. In one supermassive system called BL Lacertae, weighing 200 million times the mass of our Sun, scientists have inferred time delays millions of times greater than what this study found. That means the size of the acceleration area of the jets is likely related to the mass of the black hole.

"We are excited because it looks as though we have found a characteristic yardstick related to the inner workings of jets, not only in stellar-mass black holes like V404 Cygni, but also in monster supermassive ones," Gandhi said.

The next steps are to confirm this measured delay in observations of other X-ray binaries, and to develop a theory that can tie together jets in black holes of all sizes.

"Global ground and space telescopes working together were key to this discovery. But this is only a peek, and much remains to be learned. The future is really bright for understanding the extreme physics of black holes," said Fiona Harrison, principal investigator of NuSTAR and professor of astronomy at Caltech in Pasadena.

NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR's mission operations center is at UC Berkeley, and the official data archive is at NASA's High Energy Astrophysics Science Archive Research Center. ASI provides the mission's ground station and a mirror archive. Caltech manages JPL for NASA.

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NASA Highlights Science on Next Commercial Mission to Space Station

NASA will host a media teleconference at 1 p.m. EDT on Thursday, Nov. 2, to discuss select science investigations and technology demonstrations launching on the next Orbital ATK commercial resupply flight to the International Space Station.

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Ohio Students to Speak with NASA Astronauts on Space Station

Students at Shaker Heights High School in Shaker Heights, Ohio, will speak with NASA astronauts living, working and doing research aboard the International Space Station at 10:10 a.m. EDT on Wednesday, Nov. 1.

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Prolific Earth Gravity Satellites End Science Mission

After more than 15 productive years in orbit, the U.S./German GRACE (Gravity Recovery and Climate Experiment) satellite mission has ended science operations. During their mission, the twin GRACE satellites have provided unprecedented insights into how our planet is changing by tracking the continuous movement of liquid water, ice and the solid Earth.

GRACE made science measurements by precisely measuring the distance between its twin satellites, GRACE-1 and GRACE-2, which required that both spacecraft and their instruments be fully functional. Following an age-related battery issue on GRACE-2 in September, it became apparent by mid-October that GRACE-2's remaining battery capacity would not be sufficient to operate its science instruments and telemetry transmitter. Consequently, the decision was made to decommission the GRACE-2 satellite and end GRACE's science mission.

GRACE, a mission led by Principal Investigator Byron Tapley at the University of Texas at Austin, launched in March 2002 on a planned five-year mission to precisely map our planet's ever-changing gravity field. It has revealed how water, ice and solid Earth mass move on or near Earth's surface due to Earth's changing seasons, weather and climate processes, earthquakes and even human activities, such as from the depletion of large aquifers. It did thisby sensing minute changes in the gravitational pull caused by local changes in Earth's mass, which are due mostly to changes in how water is constantly being redistributed around our planet.

"GRACE has provided paradigm-shifting insights into the interactions of our planet's ocean, atmosphere and solid Earth components," said Tapley. "It has advanced our understanding of the contribution of polar ice melt to global sea level rise and the amount of atmospheric heat absorbed by the ocean. Recent applications include monitoring and managing global water resources used for consumption, agriculture and industry; and assessing flood and earthquake hazards."

GRACE used a microwave ranging system to measure the change in distance between the twin satellites to within a fraction of the diameter of a human hair over 137 miles (220 kilometers). The ranging data were combined with GPS tracking for timing, star trackers for attitude information, and an accelerometer to account for non-gravitational effects, such as atmospheric drag and solar radiation. From these data, scientists calculated the planet's gravity field monthly and monitored its changes over time.

"GRACE was an excellent example of a research satellite mission that advanced science and also provided near-term societal benefits," said Michael Freilich, director of NASA's Earth Science Division at the agency's headquarters in Washington. "Using cutting-edge technology to make exquisitely precise distance measurements, GRACE improved our scientific understanding of our complex home planet, while at the same time providing information -- such as measurements related to groundwater, drought and aquifer water storage changes worldwide -- that was used in the U.S. and internationally to improve the accuracy of environmental monitoring and forecasts."

GRACE established that measuring the redistribution of mass around Earth is an essential observation for understanding the Earth system. GRACE's monthly maps of regional gravity variations have given scientists new insights into Earth system processes. Among its innovations, GRACE has monitored the loss of ice mass from Earth's ice sheets, improved understanding of the processes responsible for sea level rise and ocean circulation, provided insights into where global groundwater resources may be shrinking or growing and where dry soils are contributing to drought, and monitored changes in the solid Earth. Users in more than 100 countries routinely download GRACE data for analyses. For more on GRACE's science accomplishments, see:

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"GRACE was a pioneering mission that advanced our understanding across the Earth system -- land, ocean and ice," said Michael Watkins, director of NASA's Jet Propulsion Laboratory in Pasadena, California, and the mission's original project scientist. "The entire mission team was creative and successful in its truly heroic efforts over the last few years, extending the science return of the mission to help minimize the gap between GRACE and its successor mission, GRACE Follow-On, scheduled to launch in early 2018."

Despite the loss of one of the twin GRACE satellites, the other satellite, GRACE-1, will continue operating through the end of 2017. "GRACE-1's remaining fuel will be used to complete previously planned maneuvers to calibrate and characterize its accelerometer to improve the final scientific return and insights from the 15-year GRACE record," said GRACE Project Scientist Carmen Boening of JPL.

Currently, GRACE-2's remaining fuel is being expended and the satellite has begun to slowly deorbit. Atmospheric reentry of GRACE-2 is expected sometime in December or January. Decommissioning and atmospheric reentry of GRACE-1 are expected in early 2018. NASA and the German Space Operations Center will jointly monitor the deorbit and reentry of both satellites.

GRACE Follow-On, a joint NASA/Helmholtz Centre Potsdam German Research Centre for Geosciences (GFZ) mission, will continue GRACE's legacy. It will also test a new laser-ranging interferometer developed by a joint German/U.S. collaboration for use in future generations of gravitational research satellites.

GRACE is a joint NASA/Deutsches Zentrum für Luft- und Raumfahrt (DLR, the German Aerospace Center) mission led by Tapley and Co-principal Investigator Frank Flechtner at GFZ. GRACE ground segment operations are co-funded by GFZ, DLR and the European Space Agency.JPL manages GRACE for NASA's Science Mission Directorate at the agency's headquarters in Washington. GRACE was the first mission launched under NASA's Earth System Science Pathfinder program, designed to develop new measurement technologies for studying the Earth system.

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Prolific Earth Gravity Satellites End Science Mission

After more than 15 productive years in orbit, the U.S./German GRACE (Gravity Recovery and Climate Experiment) satellite mission has ended science operations.

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NASA Center Directors Launch World Series Bragging Rights Duel

When it comes to space exploration, many believe America must make a choice between having human "Astros" exploring the solar system or using robotic probes as planet or asteroid "Dodgers."

NASA sees both approaches as essential to expanding the human presence in the universe. But that doesn't mean that two of NASA's centers can't engage in a little friendly rivalry when it comes to their hometown baseball teams competing in the 2017 World Series.

Houston is home to both the American League's Houston Astros and NASA's Johnson Space Center (JSC), the hub of human spaceflight, while the Los Angeles area is home to both the National League's L.A. Dodgers and NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, one of the pillars of robotic space and planetary missions.

On behalf of their respective centers, JSC Director Ellen Ochoa, who actually is a native Californian, and JPL Director Michael Watkins, who actually is a University of Texas at Austin alumnus, have decided the World Series deserves to be the subject of a little bragging rights wager.

So, here's the contest: If the Houston Astros win the best-of-seven series, Watkins will have to wear an Astros jersey for a day. If the series goes the L.A. Dodgers' way, Ochoa will wear a Dodgers jersey.

"JSC is proud to be a citizen of Houston, and, as such, we are proud of all the city's accomplishments and its great spirit," Ochoa said. "And our team is actually named after our space center, so I'm happy to be able to show support for that, and glad to have a little fun in challenging a center that, except for this week, is our close partner in exploration. I am looking forward to seeing a little bit of Houston at JPL soon."

"JPLers are proud to work and live in the Los Angeles area here in beautiful Southern California," Watkins said. "We love the chance to show our support for this great city, and for the great baseball tradition of the Dodgers. This is a nice way to have a little fun with our good friends at JSC and we hope to see some Dodger blue there shortly."

When it comes to the reality of spaceflight, the two centers have collaborated and compared notes on a variety of space projects for nearly half a century. NASA understands that robotic exploration has always been a precursor to human space exploration and that more and more, we see robots and humans flying together, helping each other explore. Rather than rivals, JSC and JPL are close teammates in expanding our knowledge of the universe and increasing the limits humanity explores.

But in the meantime, JSC invites all Astros fans to "Orange Out" and JPL invites all Dodgers fans to "Bleed Blue." May the best team win!

Follow along on Twitter with the hashtag #OutOfThisWorldSeries and on the JSC and JPL social media accounts as the two baseball teams go head to head:

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News media contacts:

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NASA Invites Media to Upcoming Space Station Cargo Launch

Media accreditation is open for launch of the next SpaceX commercial cargo resupply services mission to the International Space Station, currently targeted for no earlier than December.

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Small Asteroid or Comet 'Visits' from Beyond the Solar System

A small, recently discovered asteroid -- or perhaps a comet -- appears to have originated from outside the solar system, coming from somewhere else in our galaxy. If so, it would be the first "interstellar object" to be observed and confirmed by astronomers.

This unusual object - for now designated A/2017 U1 - is less than a quarter-mile (400 meters) in diameter and is moving remarkably fast. Astronomers are urgently working to point telescopes around the world and in space at this notable object. Once these data are obtained and analyzed, astronomers may know more about the origin and possibly composition of the object.

A/2017 U1 was discovered Oct. 19 by the University of Hawaii's Pan-STARRS 1 telescope on Haleakala, Hawaii, during the course of its nightly search for near-Earth objects for NASA. Rob Weryk, a postdoctoral researcher at the University of Hawaii Institute for Astronomy (IfA), was first to identify the moving object and submit it to the Minor Planet Center. Weryk subsequently searched the Pan-STARRS image archive and found it also was in images taken the previous night, but was not initially identified by the moving object processing.

› DOWNLOAD VIDEO How Do We Spot Near Earth Asteroids?

Weryk immediately realized this was an unusual object. "Its motion could not be explained using either a normal solar system asteroid or comet orbit," he said. Weryk contacted IfA graduate Marco Micheli, who had the same realization using his own follow-up images taken at the European Space Agency's telescope on Tenerife in the Canary Islands. But with the combined data, everything made sense. Said Weryk, "This object came from outside our solar system."

"This is the most extreme orbit I have ever seen," said Davide Farnocchia, a scientist at NASA's Center for Near-Earth Object Studies (CNEOS) at the agency's Jet Propulsion Laboratory in Pasadena, California. "It is going extremely fast and on such a trajectory that we can say with confidence that this object is on its way out of the solar system and not coming back."

The CNEOS team plotted the object's current trajectory and even looked into its future. A/2017 U1 came from the direction of the constellation Lyra, cruising through interstellar space at a brisk clip of 15.8 miles (25.5 kilometers) per second.

The object approached our solar system from almost directly "above" the ecliptic, the approximate plane in space where the planets and most asteroids orbit the Sun, so it did not have any close encounters with the eight major planets during its plunge toward the Sun. On Sept. 2, the small body crossed under the ecliptic plane just inside of Mercury's orbit and then made its closest approach to the Sun on Sept. 9. Pulled by the Sun's gravity, the object made a hairpin turn under our solar system, passing under Earth's orbit on Oct. 14 at a distance of about 15 million miles (24 million kilometers) -- about 60 times the distance to the Moon. It has now shot back up above the plane of the planets and, travelling at 27 miles per second (44 kilometers per second) with respect to the Sun, the object is speeding toward the constellation Pegasus.

"We have long suspected that these objects should exist, because during the process of planet formation a lot of material should be ejected from planetary systems. What's most surprising is that we've never seen interstellar objects pass through before," said Karen Meech, an astronomer at the IfA specializing in small bodies and their connection to solar system formation.

The small body has been assigned the temporary designation A/2017 U1 by the Minor Planet Center (MPC) in Cambridge, Massachusetts, where all observations on small bodies in our solar system -- and now those just passing through -- are collected. Said MPC Director Matt Holman, "This kind of discovery demonstrates the great scientific value of continual wide-field surveys of the sky, coupled with intensive follow-up observations, to find things we wouldn't otherwise know are there."

Since this is the first object of its type ever discovered, rules for naming this type of object will need to be established by the International Astronomical Union.

"We have been waiting for this day for decades," said CNEOS Manager Paul Chodas. "It's long been theorized that such objects exist -- asteroids or comets moving around between the stars and occasionally passing through our solar system -- but this is the first such detection. So far, everything indicates this is likely an interstellar object, but more data would help to confirm it."

The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) is a wide-field survey observatory operated by the University of Hawaii Institute for Astronomy. The Minor Planet Center is hosted by the Harvard-Smithsonian Center for Astrophysics and is a sub-node of NASA's Planetary Data System Small Bodies Node at the University of Maryland (http://ift.tt/17G9IxK ). JPL hosts the Center for Near-Earth Object Studies (CNEOS). All are projects of NASA's Near-Earth Object Observations Program, and elements of the agency's Planetary Defense Coordination Office within NASA's Science Mission Directorate.

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

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

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News Media Contact

DC Agle

Jet Propulsion Laboratory, Pasadena, Calif.

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Dawn Finds Possible Ancient Ocean Remnants at Ceres

Minerals containing water are widespread on Ceres, suggesting the dwarf planet may have had a global ocean in the past. What became of that ocean? Could Ceres still have liquid today? Two new studies from NASA's Dawn mission shed light on these questions.

The Dawn team found that Ceres' crust is a mixture of ice, salts and hydrated materials that were subjected to past and possibly recent geologic activity, and that this crust represents most of that ancient ocean. The second study builds off the first and suggests there is a softer, easily deformable layer beneath Ceres' rigid surface crust, which could be the signature of residual liquid left over from the ocean, too.

"More and more, we are learning that Ceres is a complex, dynamic world that may have hosted a lot of liquid water in the past, and may still have some underground," said Julie Castillo-Rogez, Dawn project scientist and co-author of the studies, based at NASA's Jet Propulsion Laboratory, Pasadena, California.

What's inside Ceres? Gravity will tell.

Landing on Ceres to investigate its interior would be technically challenging and would risk contaminating the dwarf planet. Instead, scientists use Dawn's observations in orbit to measure Ceres' gravity, in order to estimate its composition and interior structure.

The first of the two studies, led by Anton Ermakov, a postdoctoral researcher at JPL, used shape and gravity data measurements from the Dawn mission to determine the internal structure and composition of Ceres. The measurements came from observing the spacecraft's motions with NASA's Deep Space Network to track small changes in the spacecraft's orbit. This study is published in the Journal of Geophysical Research.

Ermakov and his colleagues' research supports the possibility that Ceres is geologically active -- if not now, then it may have been in the recent past. Three craters -- Occator, Kerwan and Yalode -- and Ceres' solitary tall mountain, Ahuna Mons, are all associated with "gravity anomalies." This means discrepancies between the scientists' models of Ceres' gravity and what Dawn observed in these four locations can be associated with subsurface structures.

"Ceres has an abundance of gravity anomalies associated with outstanding geologic features," Ermakov said. In the cases of Ahuna Mons and Occator, the anomalies can be used to better understand the origin of these features, which are believed to be different expressions of cryovolcanism.

The study found the crust's density to be relatively low, closer to that of ice than rocks. However, a study by Dawn guest investigator Michael Bland of the U.S. Geological Survey indicated that ice is too soft to be the dominant component of Ceres' strong crust. So, how can Ceres' crust be as light as ice in terms of density, but simultaneously much stronger? To answer this question, another team modeled how Ceres' surface evolved with time.

A 'Fossil' Ocean at Ceres

The second study, led by Roger Fu at Harvard University in Cambridge, Massachusetts, investigated the strength and composition of Ceres' crust and deeper interior by studying the dwarf planet's topography. This study is published in the journal Earth and Planetary Science Letters

By studying how topography evolves on a planetary body, scientists can understand the composition of its interior. A strong, rock-dominated crust can remain unchanged over the 4.5-billion-year-old age of the solar system, while a weak crust rich in ices and salts would deform over that time.

By modeling how Ceres' crust flows, Fu and colleagues found it is likely a mixture of ice, salts, rock and an additional component believed to be clathrate hydrate. A clathrate hydrate is a cage of water molecules surrounding a gas molecule. This structure is 100 to 1,000 times stronger than water ice, despite having nearly the same density.

The researchers believe Ceres once had more pronounced surface features, but they have smoothed out over time. This type of flattening of mountains and valleys requires a high-strength crust resting on a more deformable layer, which Fu and colleagues interpret to contain a little bit of liquid.

The team thinks most of Ceres' ancient ocean is now frozen and bound up in the crust, remaining in the form of ice, clathrate hydrates and salts. It has mostly been that way for more than 4 billion years. But if there is residual liquid underneath, that ocean is not yet entirely frozen. This is consistent with several thermal evolution models of Ceres published prior to Dawn's arrival there, supporting the idea that Ceres' deeper interior contains liquid left over from its ancient ocean.

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

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More information about Dawn is available at the following sites:

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Written by Elyssia Widjaja

NASA-JPL News Office

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NASA Awards Multiple Construction Contracts

NASA has awarded 24 Multiple Award Construction Contract Two (MACC-II) contracts to 20 small businesses and four under full and open competition to large firms for general construction services at NASA’s Stennis Space Center in Bay St. Louis, Mississippi, and several other agency locations.

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Mars Rover Mission Progresses Toward Resumed Drilling

NASA's Mars rover Curiosity team is working to restore Curiosity's sample-drilling capability using new techniques. The latest development is a preparatory test on Mars.

The five-year-old mission is still several months from the soonest possible resumption of drilling into Martian rocks. Managers are enthusiastic about successful Earth-based tests of techniques to work around a mechanical problem that appeared late last year and suspended use of the rover's drill.

"We're steadily proceeding with due caution to develop and test ways of using the rover differently from ever before, and Curiosity is continuing productive investigations that don't require drilling," said Deputy Project Manager Steve Lee, of NASA's Jet Propulsion Laboratory, Pasadena, California.

Curiosity touched its drill to the ground Oct. 17 for the first time in 10 months. It pressed the drill bit downward, and then applied smaller sideways forces while taking measurements with a force sensor.

"This is the first time we've ever placed the drill bit directly on a Martian rock without stabilizers," said JPL's Douglas Klein, chief engineer for the mission's return-to-drilling development. "The test is to gain better understanding of how the force/torque sensor on the arm provides information about side forces."

This sensor gives the arm a sense of touch about how hard it is pressing down or sideways. Avoiding too much side force in drilling into a rock and extracting the bit from the rock is crucial to avoid having the bit get stuck in the rock.

Curiosity has used its drill to acquire sample material from Martian rocks 15 times so far, from 2013 to 2016. It collected powdered rock samples that were delivered to laboratory instruments inside the rover. On each of those occasions, two contact posts -- the stabilizers on either side of the bit -- were placed on the target rock while the bit was in a withdrawn position. Then a motorized feed mechanism within the drill extended the bit forward, and the bit's rotation and percussion actions penetrated the rock.

The drill's feed mechanism stopped working reliably in December 2016. After exploring possibilities of restoring the feed mechanism's reliability or using it despite unreliability, the project set a priority to develop an alternative method of drilling without use of the feed mechanism. The promising alternative uses motion of the robotic arm to directly advance the extended bit into a rock.

"We're replacing the one-axis motion of the feed mechanism with an arm that has five degrees of freedom of motion," Klein said. "That's not simple. It's fortunate the arm has the force/torque sensor."

The sensor's main use until now has been to monitor for a force so excessive of expectations that it would automatically halt all arm motion for the day. The new "feed-extended" drilling uses it to compensate for side loads. This test will help engineers determine how data from the sensor can be used most effectively.

Using this method, a near-twin of Curiosity at JPL has collected drilled samples from Earth rocks. The team has also developed methods to deliver drilled samples to the laboratory-instrument inlets on the test rover's deck without use of the drill's feed mechanism. Development of this alternative sample-transfer technique is needed because the process used previously depended on having the bit in a withdrawn, rather than extended, position.

"The development work and testing here at JPL has been promising," Lee said. "The next step is to assess the force/torque sensor on Mars. We've made tremendous progress in developing feed-extended drilling, using the rover's versatile capabilities beyond the original design concepts. While there are still uncertainties that may complicate attempts to drill on Mars again, we are optimistic."

The rover's current location is on "Vera Rubin Ridge" on lower Mount Sharp. Curiosity is nearing the top of the 20-story-tall ridge. It has been studying the extent and distribution of the iron-oxide mineral hematite in the rocks that make up the erosion-resistant ridge.

During the first year after Curiosity's landing near Mount Sharp, the mission accomplished a major goal by determining that, billions of years ago, a Martian lake offered conditions that would have been favorable for microbial life. Curiosity has since traversed through a diversity of environments where both water and wind have left their imprint. Vera Rubin Ridge and layers above it that contain clay and sulfate minerals provide tempting opportunities to learn even more about the history and habitability of ancient Mars. For more about Curiosity, visit:

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2017-276

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International Space Station Crew Invites Public Along for Photographic Trip Around World

NASA astronaut and Expedition 53 Commander Randy Bresnik will spend one full orbit photographing Earth from the International Space Station on Monday, Oct. 23, and he is inviting people around the globe to share images from their Earth-side vantage point on social media.

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NASA Awards Launch Services Contract for Landsat 9 Mission

NASA has selected United Launch Services LLC (ULS) of Centennial, Colorado, to provide launch services for the Landsat 9 mission. The mission is currently targeted for a contract launch date of June 2021, while protecting for the ability to launch as early as December 2020, on an Atlas V 401 rocket from Space Launch Complex 3E at Vandenberg Air For

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NASA Awards Launch Services Contract for Sentinel-6A Mission

NASA has selected Space Exploration Technologies (SpaceX) of Hawthorne, California, to provide launch services for the Sentinel-6A mission. Launch is currently targeted for November 2020, on a SpaceX Falcon 9 Full Thrust rocket from Space Launch Complex 4E at Vandenberg Air Force Base in California.

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Dawn Mission Extended at Ceres

NASA has authorized a second extension of the Dawn mission at Ceres, the largest object in the asteroid belt between Mars and Jupiter. During this extension, the spacecraft will descend to lower altitudes than ever before at the dwarf planet, which it has been orbiting since March 2015. The spacecraft will continue at Ceres for the remainder of its science investigation and will remain in a stable orbit indefinitely after its hydrazine fuel runs out.

The Dawn flight team is studying ways to maneuver Dawn into a new elliptical orbit, which may take the spacecraft to less than 120 miles (200 kilometers) from the surface of Ceres at closest approach. Previously, Dawn's lowest altitude was 240 miles (385 kilometers).

A priority of the second Ceres mission extension is collecting data with Dawn's gamma ray and neutron spectrometer, which measures the number and energy of gamma rays and neutrons. This information is important for understanding the composition of Ceres' uppermost layer and how much ice it contains.

The spacecraft also will take visible-light images of Ceres' surface geology with its camera, as well as measurements of Ceres' mineralogy with its visible and infrared mapping spectrometer.

The extended mission at Ceres additionally allows Dawn to be in orbit while the dwarf planet goes through perihelion, its closest approach to the Sun, which will occur in April 2018. At closer proximity to the Sun, more ice on Ceres' surface may turn to water vapor, which may in turn contribute to the weak transient atmosphere detected by the European Space Agency's Herschel Space Observatory before Dawn's arrival. Building on Dawn's findings, the team has hypothesized that water vapor may be produced in part from energetic particles from the Sun interacting with ice in Ceres' shallow surface.Scientists will combine data from ground-based observatories with Dawn's observations to further study these phenomena as Ceres approaches perihelion.

The Dawn team is currently refining its plans for this next and final chapter of the mission. Because of its commitment to protect Ceres from Earthly contamination, Dawn will not land or crash into Ceres. Instead, it will carry out as much science as it can in its final planned orbit, where it will stay even after it can no longer communicate with Earth. Mission planners estimate the spacecraft can continue operating until the second half of 2018.

Dawn is the only mission ever to orbit two extraterrestrial targets. It orbited giant asteroid Vesta for 14 months from 2011 to 2012, then continued on to Ceres, where it has been in orbit since March 2015.

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

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Take a Walk on Mars -- in Your Own Living Room

When NASA scientists want to follow the path of the Curiosity rover on Mars, they can don a mixed-reality headset and virtually explore the Martian landscape.

Starting today, everyone can get a taste of what that feels like. NASA's Jet Propulsion Laboratory in Pasadena, California, collaborated with Google to produce Access Mars, a free immersive experience. It's available for use on all desktop and mobile devices and virtual reality/augmented reality (VR/AR) headsets. That includes mobile-based virtual reality devices on Apple and Android.

The experience was adapted from JPL's OnSight software, which assists scientists in planning rover drives and even holding meetings on Mars. Imagery from NASA's Curiosity rover provided the terrain, allowing users to wander the actual dunes and valleys explored by the spacecraft. Since being rolled out to JPL's scientists in 2015, OnSight has made studying Martian geology as intuitive as turning your head and walking around.

Access Mars lets anyone with an internet connection take a guided tour of what those scientists experience. A simple walkthrough explains what the Curiosity rover does and details its dramatic landing in 2012. Users also can visit four sites that have been critical to NASA's Mars Science Laboratory mission: Curiosity's landing site; Murray Buttes; Marias Pass and Pahrump Hills. Additionally, the rover's latest location on lower Mt. Sharp will be periodically updated to reflect the mission's ongoing progress.

At the first three locations, users can zero in on objects of scientific interest, including rock outcrops and mud cracks. Katie Stack Morgan, a JPL scientist on the MSL mission, will explain the evidence of habitability Curiosity has unearthed.

More than anything, Access Mars offers a visceral impression of what it would be like to walk alongside Curiosity, wandering through the lonely, red desert.

"We've been able to leverage VR and AR technologies to take our scientists to Mars every single day," said Victor Luo, lead project manager at JPL's Ops Lab, which led the collaboration. "With Access Mars, everyone in the world can ride along."

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Access Mars was created using data collected by JPL and built on WebVR, an open-source standard, in an effort to expand access to immersive experiences. Google's Creative Labs team was looking for novel uses for VR and encouraged developers to experiment using its tools.

NASA has collaborated with a number of outside organizations to create immersive experiences that allow people to "travel" to distant destinations. NASA worked with Google Expeditions, a free immersive app, to provide 360 tours of JPL Mars rover sites, the International Space Station and other NASA locations, and to profile the careers of women at NASA. JPL also teamed with Microsoft to create OnSight for that company's HoloLens mixed-reality headset. Using JPL's OnSight software, Microsoft collaborated on a public experience called "Destination: Mars" at Kennedy Space Center Visitor Complex in 2016.

"Immersive technology has incredible potential as a tool for scientists and engineers," Luo said. "It also lets us inspire and engage the public in new ways."

Experience Access Mars here:

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Georgia Students to Speak with NASA Astronauts on Space Station

Students at New Prospect Elementary School in Alpharetta, Georgia, will speak with the NASA astronauts living, working and doing research aboard the International Space Station at 10:50 a.m. EDT on Monday, Oct. 23.

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NASA Damage Map Aids California Wildfire Response

The Advanced Rapid Imaging and Analysis (ARIA) team at NASA's Jet Propulsion Laboratory and at Caltech, both in Pasadena, California, created a damage proxy map depicting areas in Northern California that are likely damaged as a result of the region's current outbreak of wildfires. The map has been provided to various agencies to aid in the wildfire response.

The map is derived from synthetic aperture radar (SAR) images taken before and after this month's northern California fires by the Copernicus Sentinel-1 satellites, operated by ESA (the European Space Agency). The "before" image was taken on Sept. 27, 2017, and the later image on Oct. 9, 2017. Both images were taken at 7 p.m. PDT (10 p.m. EDT).

The damage proxy map covers the full area within the large red polygon at the bottom and measures 155 by 106 miles (250 by 170 kilometers). The inset figure at the top shows a small part of the map covering damage in the city of Santa Rosa, indicated by red and yellow pixels. Each pixel measures about 98 feet (30 meters) across. The color variation from yellow to red indicates increasingly more significant ground surface change. Preliminary validation was done by comparing the map to optical satellite imagery from DigitalGlobe. This damage proxy map should be used as guidance to identify damaged areas and may be less reliable over vegetated areas.

Sentinel-1 data were accessed through the Copernicus Open Access Hub. The image contains modified Copernicus Sentinel data (2017), processed by ESA and analyzed by the NASA-JPL/Caltech ARIA team. This research was carried out at JPL under a contract with NASA.

The full map data files may be downloaded at:

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2017-273

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Deep Space Communications via Faraway Photons

A spacecraft destined to explore a unique asteroid will also test new communication hardware that uses lasers instead of radio waves.

The Deep Space Optical Communications (DSOC) package aboard NASA's Psyche mission utilizes photons -- the fundamental particle of visible light -- to transmit more data in a given amount of time. The DSOC goal is to increase spacecraft communications performance and efficiency by 10 to 100 times over conventional means, all without increasing the mission burden in mass, volume, power and/or spectrum.

Tapping the advantages offered by laser communications is expected to revolutionize future space endeavors - a major objective of NASA's Space Technology Mission Directorate (STMD).

The DSOC project is developing key technologies that are being integrated into a deep space-worthy Flight Laser Transceiver (FLT), high-tech work that will advance this mode of communications to Technology Readiness Level (TRL) 6. Reaching a TRL 6 level equates to having technology that is a fully functional prototype or representational model.

As a "game changing" technology demonstration, DSOC is exactly that. NASA STMD's Game Changing Development Program funded the technology development phase of DSOC. The flight demonstration is jointly funded by STMD, the Technology Demonstration Mission (TDM) Program and NASA/ HEOMD/Space Communication and Navigation (SCaN).

Work on the laser package is based at NASA's Jet Propulsion Laboratory in Pasadena, California.

"Things are shaping up reasonably and we have a considerable amount of test activity going on," says Abhijit Biswas, DSOC Project Technologist in Flight Communications Systems at JPL. Delivery of DSOC for integration within the Psyche mission is expected in 2021 with the spacecraft launch to occur in the summer of 2022, he explains.

"Think of the DSOC flight laser transceiver onboard Psyche as a telescope," Biswas explains, able to receive and transmit laser light in precisely timed photon bursts.

DSOC architecture is based on transmitting a laser beacon from Earth to assist line­of­sight stabilization to make possible the pointing back of a downlink laser beam. The laser onboard the Psyche spacecraft, Biswas says, is based on a master-oscillator power amplifier that uses optical fibers.

The laser beacon to DSOC will be transmitted from JPL's Table Mountain Facility located near the town of Wrightwood, California, in the Angeles National Forest. DSOC's beaming of data from space will be received at a large aperture ground telescope at Palomar Mountain Observatory in California, near San Diego.

Biswas anticipates operating DSOC perhaps 60 days after launch, given checkout of the Psyche spacecraft post-liftoff. The test-runs of the laser equipment will occur over distances of 0.1 to 2.5 astronomical units (AU) on the outward-bound probe. One AU is approximately 150 million kilometers-or the distance between the Earth and Sun.

"I am very excited to be on the mission," says Biswas, who has been working on the laser communications technology since the late 1990s. "It's a unique privilege to be working on DSOC."

The Psyche mission was selected for flight in early 2017 under NASA's Discovery Program, a series of lower-cost, highly focused robotic space missions that are exploring the solar system.

The spacecraft will be launched in the summer of 2022 to 16 Psyche, a distinctive metal asteroid about three times farther away from the sun than Earth. The planned arrival of the probe at the main belt asteroid will take place in 2026.

Lindy Elkins-Tanton is Director of the School of Earth and Space Exploration at Arizona State University in Tempe. She is the principal investigator for the Psyche mission.

"I am thrilled that Psyche is getting to fly the Deep Space Optical Communications package," Elkins-Tanton says. "First of all, the technology is mind-blowing and it brings out all my inner geek. Who doesn't want to communicate using lasers, and multiply the amount of data we can send back and forth?"

Elkins-Tanton adds that bringing robotic and human spaceflight closer together is critical for humankind's space future. "Having our robotic mission test technology that we hope will help us eventually communicate with people in deep space is excellent integration of NASA missions and all of our goals," she says.

In designing a simple, high-heritage spacecraft to do the exciting exploration of the metal world Psyche, "I find both the solar electric propulsion and the Deep Space Optical Communications to feel futuristic in the extreme. I'm proud of NASA and of our technical community for making this possible," Elkins-Tanton concludes.

Biswas explains that DSOC is a pathfinder experiment. The future is indeed bright for the technology, he suggests, such as setting up capable telecommunications infrastructure around Mars.

"Doing so would allow the support of astronauts going to and eventually landing on Mars," Biswas said. "Laser communications will augment that capability tremendously. The ability to send back from Mars to Earth lots of information, including the streaming of high definition imagery, is going to be very enabling."

As a "game changing" technology demonstration, DSOC is exactly that. NASA STMD's Game Changing Development program funded the technology development phase of DSOC. The flight demonstration is jointly funded by STMD, the Technology Demonstration Missions (TDM) program and NASA/ HEOMD/Space Communication and Navigation (SCaN). Work on the laser package is based at the Jet Propulsion Laboratory in Pasadena, California.

For more information about NASA's Technology Demonstration Missions program, visit:

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For more information about NASA's Space Technology Mission Directorate, visit:

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Gina Anderson

NASA Headquarters, Washington

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Andrew Good

Jet Propulsion Laboratory, Pasadena, Calif.

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andrew.c.good@jpl.nasa.gov

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2017-272

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Fresh Findings From Cassini

NASA's Cassini spacecraft ended its journey on Sept. 15 with an intentional plunge into the atmosphere of Saturn, but analysis continues on the mountain of data the spacecraft sent during its long life. Some of the Cassini team's freshest insights were presented during a news conference today at the American Astronomical Society Division for Planetary Science meeting in Provo, Utah.

Among the findings being shared:

-- Views from Cassini's Grand Finale show the beauty of the rings and demonstrate processes similar to those that form planets.

During Cassini's final months, the spacecraft's cameras captured views from within the gap between the planet and the rings, and the mission is releasing two new image mosaics showing the rings from that unique perspective. One view, from May 28, 2017, shows the rings emerging from behind the planet's hazy limb, while the planet itself is adorned with ring shadows. The other mosaic shows a panoramic view outward across the ringscape.

Researchers also shared a new movie of Saturn's auroras in ultraviolet light that represents the final such view from the spacecraft's Ultraviolet Imaging Spectrometer.

In addition, Cassini participating scientist and imaging team associate Matt Tiscareno of SETI Institute, Mountain View, California, provided new details about the whimsically named ring features called propellers, which are wakes in the rings created by small, unseen moonlets. The propellers are analogous to baby planets forming in disks around young stars, as they obey similar physical processes.

Tiscareno said that, in its last images of the rings (taken the day before the spacecraft's plunge into Saturn), Cassini successfully imaged all six of the propellers whose orbits were being tracked over the last several years of the mission. These objects are named for famous aviators: Blériot, Earhart, Santos-Dumont, Sikorsky, Post and Quimby. During its Ring-Grazing Orbits -- the four months of close orbits that preceeded the mission's Grand Finale -- Cassini obtained images showing swarms of smaller propellers, astounding Tiscareno and colleagues.

-- Cassini's electronic "nose" hit the jackpot, finding many surprises as it sniffed the gases in the previously unexplored space between the planet and the rings.

The spacecraft's Ion and Neutral Mass Spectrometer (INMS) returned a host of first-ever direct measurements of the components in Saturn's upper atmosphere, which stretches almost to the rings. From these observations, the team sees evidence that molecules from the rings are raining down onto the atmosphere. This influx of material from the rings was expected, but INMS data show hints of ingredients more complex than just water, which makes up the bulk of the rings' composition. In particular, the instrument detected methane, a volatile molecule that scientists would not expect to be abundant in the rings or found so high in Saturn's atmosphere. Cassini participating scientist and INMS team associate Mark Perry from the Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, says the team is busy analyzing data from the final, lowest-altitude passes, which show even more complexity and variability. The INMS observations complement those by Cassini's Cosmic Dust Analyzer instrument, which sampled solid particles in the gap during the Grand Finale.

-- Researchers continue trying to wrangle insights about the length of the planet's day from measurements of Saturn's magnetic field.

Michele Dougherty, leader of Cassini's Magnetometer team from Imperial College London, provided an update on the team's progress in trying to determine whether Saturn's magnetic field has a detectable tilt. One aim of their work is to determine the precise length of time for the planet's internal rotation, which would help researchers nail down the true length of the planet's day. Dougherty says the sensitivity of Cassini's magnetic field measurements nearly quadrupled over the course of the spacecraft's 22 Grand Finale orbits -- meaning that, if the tilt of Saturn's field is greater than 0.016 degrees, researchers should be able to detect it. An extremely small tilt is challenging to explain with scientists' current understanding of how planetary magnetic fields are generated, thus suggesting more sophisticated dynamics inside Saturn.

-- New theoretical reseach explains the forces that keep Saturn's rings from spreading out and dispersing. It turns out to be a group effort.

Key among the questions scientists hope to answer using data from Cassini are the age and origins of the rings. Theoretical modeling has shown that, without forces to confine them, the rings would spread out over hundreds of millions of years -- much younger than Saturn itself. This spreading happens because faster-moving particles that orbit closer to Saturn occasionally collide with slower particles on slightly farther-out orbits. When this happens, some momentum from the faster particles is transferred to the slower particles, speeding the latter up in their orbit and causing them to move farther outward. The inverse happens to the faster, inner particles.

Previous research had shown that gravitational tugs from the moon Mimas are solely responsible for halting the outward spread of Saturn's B ring -- that ring's outer edge is defined by the dark region known as the Cassini Division. Ring scientists had thought the small moon Janus was responsible for confining the outer edge of the A ring. But a new modeling study led by Radwan Tajeddine of Cornell University, Ithaca, New York, shows that the A ring's outward creep is kept in check by a confederation of moons, including Pan, Atlas, Prometheus, Pandora, Janus, Epimetheus and Mimas.

The insight was made possible by Cassini, which provided scientists with high-resolution views of intricate waves in the rings, along with precise determinations of the masses of Saturn's moons. Analysis of these data led Tajeddine and colleagues to an understanding that a cumulative effect of waves from all these moons damps the outward transfer of momentum in the A ring and confines its edge.

Tajeddine will present these results in a poster at the DPS meeting, and they will be published Wednesday in the Astrophysical Journal.

"There are whole careers to be forged in the analysis of data from Cassini," said Linda Spilker, the mission's project scientist at NASA's Jet Propulsion Laboratory, Pasadena, California. "In a sense, the work has only just begun."

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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NASA Missions Catch First Light from a Gravitational-Wave Event

For the first time, NASA scientists have detected light tied to a gravitational-wave event, thanks to two merging neutron stars in the galaxy NGC 4993, located about 130 million light-years from Earth in the constellation Hydra.

Shortly after 5:41 a.m. PDT (8:41 a.m. EDT) on Aug. 17, NASA's Fermi Gamma-ray Space Telescope picked up a pulse of high-energy light from a powerful explosion, which was immediately reported to astronomers around the globe as a short gamma-ray burst. The scientists at the National Science Foundation's Laser Interferometer Gravitational-wave Observatory (LIGO) detected gravitational waves dubbed GW170817 from a pair of smashing stars tied to the gamma-ray burst, encouraging astronomers to look for the aftermath of the explosion. Shortly thereafter, the burst was detected as part of a follow-up analysis by ESA's (European Space Agency's) INTEGRAL satellite.

NASA's Swift, Hubble, Chandra and Spitzer missions, along with dozens of ground-based observatories, including the NASA-funded Pan-STARRS survey, later captured the fading glow of the blast's expanding debris.

"This is extremely exciting science," said Paul Hertz, director of NASA's Astrophysics Division at the agency's headquarters in Washington. "Now, for the first time, we've seen light and gravitational waves produced by the same event. The detection of a gravitational-wave source's light has revealed details of the event that cannot be determined from gravitational waves alone. The multiplier effect of study with many observatories is incredible."

Neutron stars are the crushed, leftover cores of massive stars that previously exploded as supernovas long ago. The merging stars likely had masses between 10 and 60 percent greater than that of our Sun, but they were no wider than Washington, D.C. The pair whirled around each other hundreds of times a second, producing gravitational waves at the same frequency. As they drew closer and orbited faster, the stars eventually broke apart and merged, producing both a gamma-ray burst and a rarely seen flare-up called a "kilonova."

"This is the one we've all been waiting for," said David Reitze, executive director of the LIGO Laboratory at Caltech in Pasadena, California. "Neutron star mergers produce a wide variety of light because the objects form a maelstrom of hot debris when they collide. Merging black holes -- the types of events LIGO and its European counterpart, Virgo, have previously seen -- very likely consume any matter around them long before they crash, so we don't expect the same kind of light show."

"The favored explanation for short gamma-ray bursts is that they're caused by a jet of debris moving near the speed of light produced in the merger of neutron stars or a neutron star and a black hole," said Eric Burns, a member of Fermi's Gamma-ray Burst Monitor team at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "LIGO tells us there was a merger of compact objects, and Fermi tells us there was a short gamma-ray burst. Together, we know that what we observed was the merging of two neutron stars, dramatically confirming the relationship."

Within hours of the initial Fermi detection, LIGO and the Virgo detector at the European Gravitational Observatory near Pisa, Italy, greatly refined the event's position in the sky with additional analysis of gravitational wave data. Ground-based observatories then quickly located a new optical and infrared source -- the kilonova -- in NGC 4993.

To Fermi, this appeared to be a typical short gamma-ray burst, but it occurred less than one-tenth as far away as any other short burst with a known distance, making it among the faintest known. Astronomers are still trying to figure out why this burst is so odd, and how this event relates to the more luminous gamma-ray bursts seen at much greater distances.

NASA's Swift, Hubble and Spitzer missions followed the evolution of the kilonova to better understand the composition of this slower-moving material, while Chandra searched for X-rays associated with the remains of the ultra-fast jet.

When Swift turned to the galaxy shortly after Fermi's gamma-ray burst detection, it found a bright and quickly fading ultraviolet (UV) source.

"We did not expect a kilonova to produce bright UV emission," said Goddard's S. Bradley Cenko, principal investigator for Swift. "We think this was produced by the short-lived disk of debris that powered the gamma-ray burst."

Over time, material hurled out by the jet slows and widens as it sweeps up and heats interstellar material, producing so-called afterglow emission that includes X-rays.

But the spacecraft saw no X-rays -- a surprise for an event that produced higher-energy gamma rays.

NASA's Chandra X-ray Observatory clearly detected X-rays nine days after the source was discovered. Scientists think the delay was a result of our viewing angle, and it took time for the jet directed toward Earth to expand into our line of sight.

"The detection of X-rays demonstrates that neutron star mergers can form powerful jets streaming out at near light speed," said Goddard's Eleonora Troja, who led one of the Chandra teams and found the X-ray emission.We had to wait for nine days to detect it because we viewed it from the side, unlike anything we had seen before."

On Aug. 22, NASA's Hubble Space Telescope began imaging the kilonova and capturing its near-infrared spectrum, which revealed the motion and chemical composition of the expanding debris.

"The spectrum looked exactly like how theoretical physicists had predicted the outcome of the merger of two neutron stars would appear," said Andrew Levan at the University of Warwick in Coventry, England, who led one of the proposals for Hubble spectral observations. "It tied this object to the gravitational wave source beyond all reasonable doubt."

Astronomers think a kilonova's visible and infrared light primarily arises through heating from the decay of radioactive elements formed in the neutron-rich debris. Crashing neutron stars may be the universe's dominant source for many of the heaviest elements, including platinum and gold.

Because of its Earth-trailing orbit, Spitzer was uniquely situated to observe the kilonova long after the Sun moved too close to the galaxy for other telescopes to see it. Spitzer's Sept. 30 observation captured the longest-wavelength infrared light from the kilonova, which unveils the quantity of heavy elements forged.

"Spitzer was the last to join the party, but it will have the final word on how much gold was forged," says Mansi Kasliwal, Caltech assistant professor and principal investigator of the Spitzer observing program.

Numerous scientific papers describing and interpreting these observations have been published in Science, Nature, Physical Review Letters and The Astrophysical Journal.

Gravitational waves were directly detected for the first time in 2015 by LIGO, whose architects were awarded the 2017 Nobel Prize in physics for the discovery.

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Felicia Chou

NASA Headquarters, Washington

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Dewayne Washington

Goddard Space Flight Center, Greenbelt, Md.

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Marshall Space Flight Center, Huntsville, Ala.

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NASA Seeks Information from Potential Funders for Spitzer

NASA is seeking information from U.S. parties interested in operating the Spitzer Space Telescope with non-NASA funding after March 2019, when NASA financial support ends. Spitzer is expected to be able to support its current operations through September 2019, and operations beyond September 2020 should be possible for observing modes with the lowest data volume.

"This provides an opportunity for a public-private partnership to continue a highly successful mission," said Paul Hertz, director of the NASA Astrophysics Division in the Science Mission Directorate at Headquarters, Washington.

Spitzer's mission and spacecraft operations must remain at NASA's Jet Propulsion Laboratory, Pasadena, California, and Lockheed Martin, Littleton, Colorado. The scheduling portion of science operations and science data processing will remain at the Infrared Processing and Analysis Center at Caltech in Pasadena. The cost for operating Spitzer for fiscal year 2018 is $14 million.

Launched in 2003, Spitzer has pushed the boundaries of space science and technology numerous times while exploring the universe in infrared light. From its prime "cold" mission, it transitioned to a "warm mission" in May 2009 when the liquid helium coolant that chilled its instruments ran out.

Currently, Spitzer is in its "Beyond" phase. The name reflects the engineering challenges of a spacecraft getting farther from Earth, as well as its accomplishments. The telescope's current areas of research include topics it wasn't originally planned to address -- such as galaxies in the very early universe and exoplanets. Recently, Spitzer revealed the seven Earth-size exoplanets of TRAPPIST-1.

Full details and the request for information are found here:

https://www.fbo.gov/notices/9bbeab044b505ed30c080b98a46ff622

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

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Dwayne Brown

NASA Headquarters, Washington

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2017-269

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NASA Missions Catch First Light from a Gravitational-Wave Event

For the first time, NASA scientists have detected light tied to a gravitational-wave event, thanks to two merging neutron stars in the galaxy NGC 4993, located about 130 million light-years from Earth in the constellation Hydra.

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New Insights From OCO-2 Showcased in Science

High-resolution satellite data from NASA's Orbiting Carbon Observatory-2 are revealing the subtle ways that carbon links everything on Earth - the ocean, land, atmosphere, terrestrial ecosystems and human activities. Scientists using the first 2 1/2 years of OCO-2 data have published a special collection of five papers today in the journal Science that demonstrates the breadth of this research. In addition to showing how drought and heat in tropical forests affected global carbon dioxide levelsduring the 2015-16 El Niño, other results from these papers focus on ocean carbon release and absorption, urban emissions and a new way to study photosynthesis. A final paper by OCO-2 Deputy Project Scientist Annmarie Eldering of NASA's Jet Propulsion Laboratory in Pasadena, California, and colleagues gives an overview of the state of OCO-2 science.

Emissions From Individual Cities and Volcanoes Visible From Space

More than 70 percent of carbon dioxide emissions from human activities comes from cities, but because the gas mixes rapidly into the atmosphere, urban emissions are challenging to isolate and analyze. Florian Schwandner of JPL and colleagues used OCO-2 observations to detect how carbon dioxide emissions vary around individual cities -- the first time this has been done with data collected in just a few minutes from space. Over Los Angeles and the surrounding area, they were able to detect differences as small as 1 percent of total atmospheric carbon dioxide concentrations within the air column below the satellite.

The OCO-2 measurements across Los Angeles were detailed enough to capture differences in concentrations within the city resulting from localized sources. They also tracked diminishing carbon dioxide concentrations as the spacecraft passed from over the crowded city to the suburbs and out to the sparsely populated desert to the north.

OCO-2's orbit also allowed it to observe significant carbon dioxide signals from isolated plumes of three volcanoes on the Pacific island nation of Vanuatu. One orbit directly downwind of Mt. Yasur, which has been erupting persistently since at least the 1700s, yielded a narrow string of carbon dioxide that was about 3.4 parts per million higher than background levels -- consistent with emissions of 41.6 kilotons of carbon dioxide a day. This is a valuable quantification of volcanic emissions, which are small compared to the average human emissions of about 100,000 kilotons per day.

El Niño Suppressed Tropical Ocean's Release of Carbon

Abhishek Chatterjee of NASA's Goddard Space Flight Center in Greenbelt, Maryland, and colleagues studied how the big 2015-16 El Niño affected carbon dioxide over the tropical Pacific Ocean.

This ocean region is usually a source of carbon dioxide to the atmosphere. As part of global ocean circulation, cold, carbon-dioxide-rich water wells up to the surface in this region, and the extra carbon dioxide outgasses to the atmosphere. Because El Niño events suppress this upwelling, scientists have conjectured that it reduces the ocean's carbon dioxide emissions and therefore causes a slowdown in the growth rate of atmospheric carbon dioxide concentrations. However, until OCO-2, there haven't been adequate atmospheric observations over the remote tropical Pacific to confirm this theory.

OCO-2 data show that in the first few months of the 2015-16 El Niño, the rate of carbon dioxide released from the tropical Pacific to the atmosphere decreased by 26 to 54 percent. That translates to a short-term reduction of 0.4 to 0.5 parts per million in atmospheric concentration, or close to 0.1 percent of total atmospheric carbon dioxide.

A change of one-tenth of one percent in carbon dioxide may sound negligible, but it occurred over a region in the Pacific Ocean about the size of the entire continent of Australia. This reduction in carbon dioxide emissions for a few months was strong enough that it could be observed by OCO-2 and the National Oceanic and Atmospheric Administration's Tropical Pacific Observing System of buoys, which directly measure carbon dioxide concentrations at the surface of the ocean. The record uptick in atmospheric carbon dioxide that occurred in 2015 and 2016 would have been even greater without this decrease in tropical Pacific Ocean emissions.

With OCO-2, scientists can observe these tiny changes for the first time, a first step toward understanding the sensitivity of the carbon cycle to climate variations on a scale of years to decades.

A New Way to Measure Photosynthesis

Besides carbon dioxide, OCO-2's high-resolution spectrometers can observe solar-induced fluorescence, or SIF. This radiation, emitted by chlorophyll molecules in plants, indicates that photosynthesis is occurring. SIF provides valuable insight into global photosynthesis because it captures photosynthesis during the growing season and also its slowdown, for example, over evergreen forests in winter, when trees maintain chlorophyll but stop absorbing carbon dioxide from the atmosphere.

Ying Sun of Cornell University in Ithaca, New York, and colleagues report on OCO-2's unique SIF measurements, which provide a much higher spatial resolution than any previous system. The improved resolution enabled the scientists to perform the first-ever validation of SIF from concurrent airborne observations.

OCO-2's smaller image "footprint" on Earth allowed the researchers to do a more direct comparison of the satellite measurements with ground-based measurements of flows of carbon dioxide between plants and the air. They found a consistent relationship between SIF and carbon dioxide uptake in plants across different types of ecosystems. This finding sets the direction for in-depth studies that may further illuminate the relationship between SIF and global photosynthesis.

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Written by Carol Rasmussen

NASA's Earth Science News Team

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Facebook Live with Astronauts Kicks Off Year of Education on Space Station

The first major event for the Year of Education on Station (YES) will be hosted by NASA astronaut Joe Acaba and ESA (European Space Agency) astronaut Paolo Nespoli on a special Facebook Live broadcast from the International Space Station.

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NASA Pinpoints Cause of Earth’s Recent Record Carbon Dioxide Spike

A new NASA study provides space-based evidence that Earth’s tropical regions were the cause of the largest annual increases in atmospheric carbon dioxide concentration seen in at least 2,000 years.

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NASA Pinpoints Cause of Earth's Recent Record Carbon Dioxide Spike

A new NASA study provides space-based evidence that Earth's tropical regions were the cause of the largest annual increases in atmospheric carbon dioxide concentration seen in at least 2,000 years.

Scientists suspected the 2015-16 El Nino -- one of the largest on record -- was responsible, but exactly how has been a subject of ongoing research. Analyzing the first 28 months of data from NASA's Orbiting Carbon Observatory-2 (OCO-2) satellite, researchers conclude impacts of El Nino-related heat and drought occurring in tropical regions of South America, Africa and Indonesia were responsible for the record spike in global carbon dioxide. The findings are published in the journal Science Friday as part of a collection of five research papers based on OCO-2 data.

"These three tropical regions released 2.5 gigatons more carbon into the atmosphere than they did in 2011," said Junjie Liu of NASA's Jet Propulsion Laboratory in Pasadena, California, who is lead author of the study. "Our analysis shows this extra carbon dioxide explains the difference in atmospheric carbon dioxide growth rates between 2011 and the peak years of 2015-16. OCO-2 data allowed us to quantify how the net exchange of carbon between land and atmosphere in individual regions is affected during El Nino years." A gigaton is a billion tons.

In 2015 and 2016, OCO-2 recorded atmospheric carbon dioxide increases that were 50 percent larger than the average increase seen in recent years preceding these observations. These measurements are consistent with those made by the National Oceanic and Atmospheric Administration (NOAA). That increase was about 3 parts per million of carbon dioxide per year -- or 6.3 gigatons of carbon. In recent years, the average annual increase has been closer to 2 parts per million of carbon dioxide per year -- or 4 gigatons of carbon. These record increases occurred even though emissions from human activities in 2015-16 are estimated to have remained roughly the same as they were prior to the El Nino, which is a cyclical warming pattern of ocean circulation in the central and eastern tropical Pacific Ocean that can affect weather worldwide.

Using OCO-2 data, Liu's team analyzed how Earth's land areas contributed to the record atmospheric carbon dioxide concentration increases. They found the total amount of carbon released to the atmosphere from all land areas increased by 3 gigatons in 2015, due to the El Nino. About 80 percent of that amount -- or 2.5 gigatons of carbon -- came from natural processes occurring in tropical forests in South America, Africa and Indonesia, with each region contributing roughly the same amount.

The team compared the 2015 findings to those from a reference year -- 2011 -- using carbon dioxide data from the Japan Aerospace Exploration Agency's Greenhouse Gases Observing Satellite (GOSAT). In 2011, weather in the three tropical regions was normal and the amount of carbon absorbed and released by them was in balance.

"Understanding how the carbon cycle in these regions responded to El Nino will enable scientists to improve carbon cycle models, which should lead to improved predictions of how our planet may respond to similar conditions in the future," said OCO-2 Deputy Project Scientist Annmarie Eldering of JPL. "The team's findings imply that if future climate brings more or longer droughts, as the last El Nino did, more carbon dioxide may remain in the atmosphere, leading to a tendency to further warm Earth."

While the three tropical regions each released roughly the same amount of carbon dioxide into the atmosphere, the team found that temperature and rainfall changes influenced by the El Nino were different in each region, and the natural carbon cycle responded differently. Liu combined OCO-2 data with other satellite data to understand details of the natural processes causing each tropical region's response.

In eastern and southeastern tropical South America, including the Amazon rainforest, severe drought spurred by El Nino made 2015 the driest year in the past 30 years. Temperatures also were higher than normal. These drier and hotter conditions stressed vegetation and reduced photosynthesis, meaning trees and plants absorbed less carbon from the atmosphere. The effect was to increase the net amount of carbon released into the atmosphere.

In contrast, rainfall in tropical Africa was at normal levels, based on precipitation analysis that combined satellite measurements and rain gauge data, but ecosystems endured hotter-than-normal temperatures. Dead trees and plants decomposed more, resulting in more carbon being released into the atmosphere. Meanwhile, tropical Asia had the second-driest year in the past 30 years. Its increased carbon release, primarily from Indonesia, was mainly due to increased peat and forest fires -- also measured by satellite instruments.

"We knew El Ninos were one factor in these variations, but until now we didn't understand, at the scale of these regions, what the most important processes were," said Eldering. "OCO-2's geographic coverage and data density are allowing us to study each region separately."

Scott Denning, professor of atmospheric science at Colorado State University in Fort Collins and an OCO-2 science team member who was not part of this study, noted that while scientists have known for decades that El Nino influences the productivity of tropical forests and, therefore, the forests' net contributions to atmospheric carbon dioxide, researchers have had very few direct observations of the effects.

"OCO-2 has given us two revolutionary new ways to understand the effects of drought and heat on tropical forests: directly measuring carbon dioxide over these regions thousands of times a day; and sensing the rate of photosynthesis by detecting fluorescence from chlorophyll in the trees themselves," said Denning. "We can use these data to test our understanding of whether the response of tropical forests is likely to make climate change worse or not."

The concentration of carbon dioxide in Earth's atmosphere is constantly changing. It changes from season to season as plants grow and die, with higher concentrations in the winter and lower amounts in the summer. Annually averaged atmospheric carbon dioxide concentrations have generally increased year over year since the early 1800s -- the start of the widespread Industrial Revolution. Before then, Earth's atmosphere naturally contained about 595 gigatons of carbon in the form of carbon dioxide. Currently, that number is 850 gigatons.

The annual increase in atmospheric carbon dioxide levels and the magnitude of the seasonal cycle are determined by a delicate balance between Earth's atmosphere, ocean and land. Each year, the ocean, plants and trees take up and release carbon dioxide. The amount of carbon released into the atmosphere as a result of human activities also changes each year. On average, Earth's land and ocean remove about half the carbon dioxide released from human emissions, with the other half leading to increasing atmospheric concentrations. While natural processes are responsible for the exchange of carbon dioxide between the atmosphere, ocean and land, each year is different. In some years, natural processes remove as little as 20 percent of human emissions, while in other years they scrub as much as 80 percent.

OCO-2, launched in 2014, gathers global measurements of atmospheric carbon dioxide with the resolution, precision and coverage needed to understand how this important greenhouse gas -- the principal human-produced driver of climate change -- moves through the Earth system at regional scales, and how it changes over time. From its vantage point in space, OCO-2 is able to make roughly 100,000 measurements of atmospheric carbon dioxide each day, around the world.

Institutions involved in the Liu study include JPL; the National Center for Atmospheric Research in Boulder, Colorado; the University of Toronto; Colorado State University; Caltech in Pasadena, California; and Arizona State University in Tempe.

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Reconstructing Cassini's Plunge into Saturn

As NASA's Cassini spacecraft made its fateful dive into the upper atmosphere of Saturn on Sept. 15, the spacecraft was live-streaming data from eight of its science instruments, along with readings from a variety of engineering systems. While analysis of science data from the final plunge will take some time, Cassini engineers already have a pretty clear understanding of how the spacecraft itself behaved as it went in. The data are useful for evaluating models of Saturn's atmosphere the team used to predict the spacecraft's behavior at mission's end, and they help provide a baseline for planning future missions to Saturn.

Chief among these engineering data, or telemetry, are measurements indicating the performance of the spacecraft's small attitude-control thrusters. Each thruster was capable of producing a force of half a newton, which is roughly equivalent to the weight of a tennis ball on Earth.

During the final moments of its plunge, Cassini was traveling through Saturn's atmosphere, which was about the same density as the tenuous gas where the International Space Station orbits above Earth. In other words, there's barely any air there at all. Despite the fact that this air pressure is close to being a vacuum, Cassini was traveling about 4.5 times faster than the space station. The higher velocity greatly multiplied the force, or dynamic pressure, that the thin atmosphere exerted on Cassini. It's like the difference between holding your hand outside the window of a car moving at 15 mph versus one moving at 65 mph.

Data show that as Cassini began its final approach, in the hour before atmospheric entry it was subtly rocking back and forth by fractions of a degree, gently pulsing its thrusters every few minutes to keep its antenna pointed at Earth. The only perturbing force at that time was a slight tug from Saturn's gravity that tried to rotate the spacecraft.

"To keep the antenna pointed at Earth, we used what's called 'bang-bang control,'" said Julie Webster, Cassini's spacecraft operations chief at NASA's Jet Propulsion Laboratory, Pasadena, California. "We give the spacecraft a narrow range over which it can rotate, and when it bangs up against that limit in one direction, it fires a thruster to tip back the other way." (This range was indeed small: just two milliradians, which equals 0.1 degree. The reconstructed data show Cassini was subtly correcting its orientation in this way until about three minutes before loss of signal.)

At this point, about 1,200 miles (1,900 kilometers) above the cloud tops, the spacecraft began to encounter Saturn's atmosphere. Cassini approached Saturn with its 36-foot-long (11-meter) magnetometer boom pointing out from the spacecraft's side. The tenuous gas began to push against the boom like a lever, forcing it to rotate slightly toward the aft (or backward) direction. In response, the thrusters fired corrective gas jets to stop the boom from rotating any farther. Over the next couple of minutes, as engineers had predicted, the thrusters began firing longer, more frequent pulses. The battle with Saturn had begun.

With its thrusters firing almost continuously, the spacecraft held its own for 91 seconds against Saturn's atmosphere -- the thrusters reaching 100 percent of their capacity during the last 20 seconds or so before the signal was lost. The final eight seconds of data show that Cassini started to slowly tip over backward. As this happened, the antenna's narrowly focused radio signal began to point away from Earth, and 83 minutes later (the travel time for a signal from Saturn), Cassini's voice disappeared from monitors in JPL mission control. First, the actual telemetry data disappeared, leaving only a radio carrier signal. Then, 24 seconds after the loss of telemetry, silence.

These data explain why those watching the signal -- appearing as a tall green spike on a squiggly plot of Cassini's radio frequency -- in mission control and live on NASA TV -- saw what appeared to be a short reprieve, almost as though the spacecraft was making a brief comeback. The spike of the signal first began to diminish over a few seconds, but then rose briefly again before disappearing with finality.

"No, it wasn't a comeback. Just a side lobe of the radio antenna beam pattern," Webster said. Essentially, the reprieve was an unfocused part of the otherwise narrow radio signal that rotated into view as the spacecraft began to slowly tip over.

"Given that Cassini wasn't designed to fly into a planetary atmosphere, it's remarkable that the spacecraft held on as long as it did, allowing its science instruments to send back data to the last second," said Earl Maize, Cassini project manager at JPL. "It was a solidly built craft, and it did everything we asked of it."

This animation shows the last 30 seconds of Cassini's X- and S-band radio signals as they disappeared from mission control on Sept. 15, 2017. The video has been sped up by a factor of two. Credit: NASA/JPL-Caltech Click to play movie

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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