Wednesday, July 23, 2014

NASA Study Eyes Soot's Role in 1800s Glacier Retreat

NASA Study Eyes Soot's Role in 1800s Glacier Retreat:

researchers and collaborators have combined historical records, ancient ice from cores in glaciers
NASA researchers and collaborators have combined historical records, ancient ice from cores in glaciers, modern air pollution studies and a model of glacier behavior to offer an explanation of why glaciers in the Alps started retreating in the late 19th century, despite cool temperatures and ample snowfall, which should have kept them growing. They find that soot from industrialization in Europe was deposited on the lower slopes of the glaciers, and that soot absorbed sunlight and accelerated melting. Although pollution sources today are not the same as in the 19th century, there is still enough pollution to make the air circulation patterns visible. This photo from summer 2012 looking south into the Bernese Alps shows how air pollution in the Alps tends to be confined to lower altitudes, concentrating the deposition of soot and dust on the lower slopes. At center left in the picture, a glacier can be seen extending from a high-altitude snow field, above the pollution layer, down into the valley where its lower reach is bathed in pollutants. Image credit: Peter Holy

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September 03, 2013

PASADENA, Calif. - A NASA-led team of scientists has uncovered strong evidence that soot from a rapidly industrializing Europe caused the abrupt retreat of mountain glaciers in the European Alps that began in the 1860s, a period often thought of as the end of the Little Ice Age.


The research, published Sept. 3 in the Proceedings of the National Academy of Sciences, may help resolve a longstanding scientific debate.


In the decades following the 1850s, Europe underwent an economic and atmospheric transformation spurred by industrialization. The use of coal to heat homes and power transportation and industry in Western Europe began in earnest, spewing huge quantities of black carbon and other dark particles into the atmosphere.


Black carbon is the strongest sunlight-absorbing atmospheric particle. When these particles settle on the snow blanketing glaciers, they darken the snow surface, speeding its melting and exposing the underlying glacier ice to sunlight and warmer spring and summer air earlier in the year. This diminishing of the snow cover earlier in each year causes the glacier ice to melt faster and retreat.


The Little Ice Age, loosely defined as a cooler period between the 14th and 19th centuries, was marked by an expansion of mountain glaciers and a drop in temperatures in Europe of nearly 1.8 degrees Fahrenheit (1 degree Celsius). But glacier records show that between 1860 and 1930, while temperatures continued to drop, large valley glaciers in the Alps abruptly retreated by an average of nearly 0.6 mile (1 kilometer) to lengths not seen in the previous few hundred years. Glaciologists and climatologists have struggled to reconcile this apparent conflict between climate and glacier records.


"Something was missing from the equation," said Thomas Painter, a snow and ice scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., who led the study. "Before now, most glaciologists believed the end of the Little Ice Age came in the mid-1800s when these glaciers retreated, and that the retreat was due to a natural climatic shift, distinct from the carbon dioxide-induced warming that came later in the 20th century. This result suggests that human influence on glaciers extends back to well before the industrial temperature increases."


To help the scientists understand what was driving the glacier retreat, Painter and his colleagues turned to history. The researchers studied data from ice cores drilled from high up on several European mountain glaciers to determine how much black carbon was in the atmosphere and snow when the Alps glaciers began to retreat. Using the levels of carbon particles trapped in the ice core layers, and taking into consideration modern observations of how pollutants are distributed in the Alps, they were able to estimate how much black carbon was deposited on glacial surfaces at lower elevations, where levels of black carbon tend to be highest.


The team then ran computer models of glacier behavior, starting with recorded weather conditions and adding the impact of the lower-elevation pollution. When this impact was included, the simulated glacier mass loss and timing finally were consistent with the historic record of glacial retreat, despite the cooling temperatures at that time.


"We must now look more closely at other regions on Earth, such as the Himalaya, to study the present-day impacts of black carbon on glaciers in these regions," said Georg Kaser, a study co-author from the University of Innsbruck, Austria, and lead author of the Working Group I Cryosphere chapter of the Intergovernmental Panel on Climate Change's upcoming Fifth Assessment Report.


"This study uncovers likely human fingerprints on our changing environment," said co-author Waleed Abdalati, director of the Cooperative Institute for Research and Environmental Sciences (CIRES) at the University of Colorado Boulder. "It's a reminder that the actions we take have far-reaching impacts on the environment in which we live."


CIRES is a joint institute of the university and the National Oceanic and Atmospheric Administration. Other institutions participating in the study include the University of Michigan - Ann Arbor and the University of California, Davis. The California Institute of Technology in Pasadena manages JPL for NASA.


For more information about NASA programs, visit: http://www.nasa.gov


Additional media contacts for this story: Katy Human, CIRES, 303-735-0196, Kathleen.human@colorado.edu ; Nicole Casal Moore, University of Michigan, 734-647-7087, ncmoore@umich.edu ; Stefan Hohenwarter, University of Innsbruck, 011-43-512-50732023, stefan.hohenwarter@uibk.ac.at ; Kat Kerlin, UC Davis, 530-752-7704, kekerlin@ucdavis.edu .

Alan Buis 818-354-0474

Jet Propulsion Laboratory, Pasadena, Calif.

Alan.buis@jpl.nasa.gov


Steve Cole 202-358-0918

NASA Headquarters, Washington

Stephen.e.cole@nasa.gov


2013-267
Posted by Nelio Inacio at 4:24 PM 0 comments

Catching Black Holes on the Fly

Catching Black Holes on the Fly:

Black Holes Shine for NuSTAR
An optical color image of galaxies is seen here overlaid with X-ray data (magenta) from NASA's Nuclear Spectroscopic Telescope Array (NuSTAR). Image credit: NASA/JPL-Caltech
› Full image and caption


September 05, 2013

NASA's black-hole-hunter spacecraft, the Nuclear Spectroscopic Telescope Array, or NuSTAR, has "bagged" its first 10 supermassive black holes. The mission, which has a mast the length of a school bus, is the first telescope capable of focusing the highest-energy X-ray light into detailed pictures.


The new black-hole finds are the first of hundreds expected from the mission over the next two years. These gargantuan structures -- black holes surrounded by thick disks of gas -- lie at the hearts of distant galaxies between 0.3 and 11.4 billion light-years from Earth.


"We found the black holes serendipitously," explained David Alexander, a NuSTAR team member based in the Department of Physics at Durham University in England and lead author of a new study appearing Aug. 20 in the Astrophysical Journal. "We were looking at known targets and spotted the black holes in the background of the images."


Additional serendipitous finds such as these are expected for the mission. Along with the mission's more targeted surveys of selected patches of sky, the NuSTAR team plans to comb through hundreds of images taken by the telescope with the goal of finding black holes caught in the background.


Once the 10 black holes were identified, the researchers went through previous data taken by NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton satellite, two complementary space telescopes that see lower-energy X-ray light. The scientists found that the objects had been detected before. It wasn't until the NuSTAR observations, however, that they stood out as exceptional, warranting closer inspection.


By combining observations taken across the range of the X-ray spectrum, the astronomers hope to crack unsolved mysteries of black holes. For example, how many of them populate the universe?


"We are getting closer to solving a mystery that began in 1962," said Alexander. "Back then, astronomers had noted a diffuse X-ray glow in the background of our sky but were unsure of its origin. Now, we know that distant supermassive black holes are sources of this light, but we need NuSTAR to help further detect and understand the black hole populations."


This X-ray glow, called the cosmic X-ray background, peaks at the high-energy frequencies that NuSTAR is designed to see, so the mission is key to identifying what's producing the light. NuSTAR can also find the most hidden supermassive black holes, buried by thick walls of gas.


"The highest-energy X-rays can pass right through even significant amounts of dust and gas surrounding the active supermassive black holes," said Fiona Harrison, a study co-author and the mission's principal investigator at the California Institute of Technology, Pasadena.


Data from NASA's Wide-field Infrared Survey Explorer, or WISE, and Spitzer missions also provide missing pieces in the puzzle of black holes by weighing the mass of their host galaxies.


"Our early results show that the more distant supermassive black holes are encased in bigger galaxies," said Daniel Stern, a co-author of the study and the project scientist for NuSTAR at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "This is to be expected. Back when the universe was younger, there was a lot more action with bigger galaxies colliding, merging and growing."


Future observations will reveal more about the beastly happenings of black holes, near and far. In addition to hunting remote black holes, NuSTAR is also searching for other exotic objects within our Milky Way galaxy.


NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA's Jet Propulsion Laboratory, also in Pasadena, for NASA's Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Va. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, New York; NASA's Goddard Space Flight Center, Greenbelt, Md.; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, Calif.; ATK Aerospace Systems, Goleta, Calif., and with support from the Italian Space Agency (ASI) Science Data Center.


NuSTAR's mission operations center is at UC Berkeley, with the ASI providing its equatorial ground station located at Malindi, Kenya. The mission's outreach program is based at Sonoma State University, Rohnert Park, Calif. NASA's Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.


For more information, visit http://www.nasa.gov/nustar and http://www.nustar.caltech.edu/ .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

Whitney.clavin@jpl.nasa.gov


2013-270
Posted by Nelio Inacio at 4:23 PM 0 comments

NASA Evaluates Four Candidate Sites for 2016 Mars Mission

NASA Evaluates Four Candidate Sites for 2016 Mars Mission:

Landing Area Narrowed for 2016 InSight Mission to Mars
The process of selecting a site for NASA's next landing on Mars, planned for September 2016, has narrowed to four semifinalist sites located close together in the Elysium Planitia region of Mars. The mission known by the acronym InSight will study the Red Planet's interior, rather than surface features, to advance understanding of the processes that formed and shaped the rocky planets of the inner solar system, including Earth. Image credit: NASA/JPL-Caltech
› Full image and caption

September 04, 2013

NASA has narrowed to four the number of potential landing sites for the agency's next mission to the surface of Mars, a 2016 lander to study the planet's interior.


The stationary Interior Exploration Using Seismic Investigations, Geodesy and Heat Transport (InSight) lander is scheduled to launch in March 2016 and land on Mars six months later. It will touch down at one of four sites selected in August from a field of 22 candidates. All four semi-finalist spots lie near each other on an equatorial plain in an area of Mars called Elysium Planitia.


"We picked four sites that look safest," said geologist Matt Golombek of NASA's Jet Propulsion Laboratory in Pasadena, Calif. Golombek is leading the site-selection process for InSight. "They have mostly smooth terrain, few rocks and very little slope."


Scientists will focus two of NASA's Mars Reconnaissance Orbiter cameras on the semi-finalists in the coming months to gain data they will use to select the best of the four sites well before InSight is launched.


The mission will investigate processes that formed and shaped Mars and will help scientists better understand the evolution of our inner solar system's rocky planets, including Earth. Unlike previous Mars landings, what is on the surface in the area matters little in the choice of a site except for safety considerations.


"This mission's science goals are not related to any specific location on Mars because we're studying the planet as a whole, down to its core," said Bruce Banerdt, InSight principal investigator at JPL. "Mission safety and survival are what drive our criteria for a landing site."


Each semifinalist site is an ellipse measuring 81 miles (130 kilometers) from east to west and 17 miles (27 kilometers) from north to south. Engineers calculate the spacecraft will have a 99-percent chance of landing within that ellipse, if targeted for the center.


Elysium is one of three areas on Mars that meet two basic engineering constraints for InSight. One requirement is being close enough to the equator for the lander's solar array to have adequate power at all times of the year. Also, the elevation must be low enough to have sufficient atmosphere above the site for a safe landing. The spacecraft will use the atmosphere for deceleration during descent.


All four semifinalist sites, as well as the rest of the 22 candidate sites studied, are in Elysium Planitia. The only other two areas of Mars meeting the requirements of being near the equator at low elevation, Isidis Planitia and Valles Marineris, are too rocky and windy. Valles Marineris also lacks any swath of flat ground large enough for a safe landing.


InSight also needs penetrable ground, so it can deploy a heat-flow probe that will hammer itself 3 yards to 5 yards into the surface to monitor heat coming from the planet's interior. This tool can penetrate through broken-up surface material or soil, but could be foiled by solid bedrock or large rocks.


"For this mission, we needed to look below the surface to evaluate candidate landing sites," Golombek said.


InSight's heat probe must penetrate the ground to the needed depth, so scientists studied Mars Reconnaissance Orbiter images of large rocks near Martian craters formed by asteroid impacts. Impacts excavate rocks from the subsurface, so by looking in the area surrounding craters, the scientists could tell if the subsurface would have probe-blocking rocks lurking beneath the soil surface.


InSight also will deploy a seismometer on the surface and will use its radio for scientific measurements.


JPL manages InSight for NASA's Science Mission Directorate in Washington. The French space agency, Centre National d'Etudes Spatiales, and the German Aerospace Center are contributing instruments to the mission. Lockheed Martin Space Systems, Denver, is building the spacecraft.


InSight is part of NASA's Discovery Program, which NASA's Marshall Space Flight Center in Huntsville, Ala., manages. InSight's team includes U.S. and international co-investigators from universities, industry and government agencies.


For more information about InSight, visit: http://insight.jpl.nasa.gov . Additional information on the Discovery Program is available at: http://discovery.nasa.gov .

Guy Webster 818-354-6278

Jet Propulsion Laboratory, Pasadena, Calif.

guy.webster@jpl.nasa.gov


Dwayne Brown 202-358-1726

NASA Headquarters, Washington

dwayne.c.brown@nasa.gov


2013-269
Posted by Nelio Inacio at 4:22 PM 0 comments

Cassini Sees Saturn Storm's Explosive Power

Cassini Sees Saturn Storm's Explosive Power:

Two Looks at the Turbulent Saturn Storm
This set of images from NASA's Cassini mission shows the turbulent power of a monster Saturn storm. The visible-light image in the back, obtained on Feb. 25, 2011, by Cassini's imaging camera, shows the turbulent clouds churning across the face of Saturn. The inset infrared image, obtained a day earlier, by Cassini's visual and infrared mapping spectrometer, shows the dredging up of water and ammonia ices from deep in Saturn's atmosphere. This was the first time water ice was detected in Saturn's atmosphere. The storm, first detected by Cassini's radio and plasma wave subsystem in December 2011, churned around the planet in a band around 33 degrees north. Image Credit:
NASA/JPL-Caltech/SSI/Univ. of Arizona/Univ. of Wisconsin
› Full image and caption
› The visible-light image can be seen separately
› A separate version of the infrared image

September 03, 2013

A monster storm that erupted on Saturn in late 2010 - as large as any storm ever observed on the ringed planet -- has already impressed researchers with its intensity and long-lived turbulence. A new paper in the journal Icarus reveals another facet of the storm's explosive power: its ability to churn up water ice from great depths. This finding, derived from near-infrared measurements by NASA's Cassini spacecraft, is the first detection at Saturn of water ice. The water originates from deep in Saturn's atmosphere.


"The new finding from Cassini shows that Saturn can dredge up material from more than 100 miles [160 kilometers]," said Kevin Baines, a co-author of the paper who works at the University of Wisconsin-Madison and NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It demonstrates in a very real sense that typically demure-looking Saturn can be just as explosive or even more so than typically stormy Jupiter." Water ice, which originates from deep in the atmosphere of gas giants, doesn't appear to be lofted as high at Jupiter.


Monster storms rip across the northern hemisphere of Saturn once every 30 years or so, or roughly once per Saturn year. The first hint of the most recent storm first appeared in data from Cassini's radio and plasma wave subsystem on Dec. 5, 2010. Soon after that, it could be seen in images from amateur astronomers and from Cassini's imaging science subsystem. The storm quickly grew to superstorm proportions, encircling the planet at about 30 degrees north latitude for an expanse of nearly 190,000 miles (300,000 kilometers).


The new paper focuses on data gathered by Cassini's visual and infrared mapping spectrometer on Feb. 24, 2011. The team, led by Lawrence Sromovsky, also of the University of Wisconsin, found that cloud particles at the top of the great storm are composed of a mix of three substances: water ice, ammonia ice, and an uncertain third constituent that is possibly ammonium hydrosulfide. The observations are consistent with clouds of different chemical compositions existing side-by-side, though it is more likely that the individual cloud particles are composed of two or all three of the materials.


The classic model of Saturn's atmosphere portrays it as a layered sandwich of sorts, with a deck of water clouds at the bottom, ammonia hydrosulfide clouds in the middle, and ammonia clouds near the top. Those layers are just below an upper tropospheric haze of unknown composition that obscures almost everything.


But this storm appears to have disrupted those neat layers, lofting up water vapor from a lower layer that condensed and froze as it rose. The water ice crystals then appeared to become coated with more volatile materials like ammonium hydrosulfide and ammonia as the temperature decreased with their ascent, the authors said.


"We think this huge thunderstorm is driving these cloud particles upward, sort of like a volcano bringing up material from the depths and making it visible from outside the atmosphere," said Sromovsky. "The upper haze is so optically thick that it is only in the stormy regions where the haze is penetrated by powerful updrafts that you can see evidence for the ammonia ice and the water ice. Those storm particles have an infrared color signature that is very different from the haze particles in the surrounding atmosphere."


In understanding the dynamics of this Saturn storm, researchers realized that it worked like the much smaller convective storms on Earth, where air and water vapor are pushed high into the atmosphere, resulting in the towering, billowing clouds of a thunderstorm. The towering clouds in Saturn storms of this type, however, were 10 to 20 times taller and covered a much bigger area. They are also far more violent than an Earth storm, with models predicting vertical winds of more than about 300 mph (500 kilometers per hour) for these rare giant storms.


The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the mission for NASA's Science Mission Directorate, Washington. The California Institute of Technology in Pasadena manages JPL for NASA. The VIMS team is based at the University of Arizona in Tucson.


For more information about the Cassini mission, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .

Jia-Rui C. Cook 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov


Terry Devitt 608-262-8282

University of Wisconsin, Madison

trdevitt@wisc.edu

2013-268
Posted by Nelio Inacio at 4:22 PM 0 comments

NASA Voyager Statement About Solar Wind Models

NASA Voyager Statement About Solar Wind Models:

The Space Between: This artist's concept shows the Voyager 1
The Space Between: This artist's concept shows the Voyager 1 spacecraft entering the space between stars. Interstellar space is dominated by plasma, ionized gas (illustrated here as brownish haze), that was thrown off by giant stars millions of years ago. Image credit: NASA/JPL-Caltech
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July 23, 2014

A paper recently published in the journal Geophysical Research Letters describes an alternate model for the interaction between the heliosphere -- a "bubble" around our planets and sun -- and the interstellar medium. It also proposes a test for whether Voyager 1 has, indeed, left the heliosphere.

NASA's Voyager project scientist, Ed Stone of the California Institute of Technology in Pasadena, responds:

"It is the nature of the scientific process that alternative theories are developed in order to account for new observations. This paper differs from other models of the solar wind and the heliosphere and is among the new models that the Voyager team will be studying as more data are acquired by Voyager."

Stone went on to explain that other models, which he and colleagues used to conclude that Voyager 1 entered interstellar space, predict that the density of interstellar wind outside the heliosphere is 40 times greater than the density of the solar wind inside.

Voyager scientists had carefully analyzed the observational data from the spacecraft, which revealed a plasma density that was 40 times higher. They then concluded that Voyager 1 had departed the solar bubble and entered interstellar space around August 25, 2012.

But the new article argues that solar wind inside the heliosphere can be compressed to the point that the solar wind density inside is just as high as interstellar space outside. Therefore, Voyager 1 could still be inside.

Authors of the new study predict that if Voyager 1 is still inside the heliosphere, the spacecraft will observe a reversal in direction of the solar magnetic field sometime before the end of 2015. Stone said he and colleagues will be looking carefully at the magnetic field data over the coming 18 months to see if Voyager picks up this change.

The Voyager spacecraft were built and continue to be operated by NASA's Jet Propulsion Laboratory, in Pasadena, California. Caltech manages JPL for NASA. The Voyager missions are a part of NASA's Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate at NASA Headquarters in Washington.

For more information about Voyager, visit:

http://www.nasa.gov/voyager
http://voyager.jpl.nasa.gov

Elizabeth Landau

NASA's Jet Propulsion Laboratory, Pasadena, Calif.

818-354-6425

Elizabeth.Landau@jpl.nasa.gov


2014-238
Posted by Nelio Inacio at 4:20 PM 0 comments

The Most Precise Measurement of an Alien World's Size

The Most Precise Measurement of an Alien World's Size:

Gauging an Alien World's Size
Using data from NASA's Kepler and Spitzer Space Telescopes, scientists have made the most precise measurement ever of the size of a world outside our solar system, as illustrated in this artist's conception.
› Full image and caption


July 23, 2014

Thanks to NASA's Kepler and Spitzer Space Telescopes, scientists have made the most precise measurement ever of the radius of a planet outside our solar system. The size of the exoplanet, dubbed Kepler-93b, is now known to an uncertainty of just 74 miles (119 kilometers) on either side of the planetary body.

The findings confirm Kepler-93b as a "super-Earth" that is about one-and-a-half times the size of our planet. Although super-Earths are common in the galaxy, none exist in our solar system. Exoplanets like Kepler-93b are therefore our only laboratories to study this major class of planet.

With good limits on the sizes and masses of super-Earths, scientists can finally start to theorize about what makes up these weird worlds. Previous measurements, by the Keck Observatory in Hawaii, had put Kepler-93b's mass at about 3.8 times that of Earth. The density of Kepler-93b, derived from its mass and newly obtained radius, indicates the planet is in fact very likely made of iron and rock, like Earth.

"With Kepler and Spitzer, we've captured the most precise measurement to date of an alien planet's size, which is critical for understanding these far-off worlds," said Sarah Ballard, a NASA Carl Sagan Fellow at the University of Washington in Seattle and lead author of a paper on the findings published in the Astrophysical Journal.

"The measurement is so precise that it's literally like being able to measure the height of a six-foot tall person to within three quarters of an inch -- if that person were standing on Jupiter," said Ballard.

Kepler-93b orbits a star located about 300 light-years away, with approximately 90 percent of the sun's mass and radius. The exoplanet's orbital distance -- only about one-sixth that of Mercury's from the sun -- implies a scorching surface temperature around 1,400 degrees Fahrenheit (760 degrees Celsius). Despite its newfound similarities in composition to Earth, Kepler-93b is far too hot for life.

To make the key measurement about this toasty exoplanet's radius, the Kepler and Spitzer telescopes each watched Kepler-93b cross, or transit, the face of its star, eclipsing a tiny portion of starlight. Kepler's unflinching gaze also simultaneously tracked the dimming of the star caused by seismic waves moving within its interior. These readings encode precise information about the star's interior. The team leveraged them to narrowly gauge the star's radius, which is crucial for measuring the planetary radius.

Spitzer, meanwhile, confirmed that the exoplanet's transit looked the same in infrared light as in Kepler's visible-light observations. These corroborating data from Spitzer -- some of which were gathered in a new, precision observing mode -- ruled out the possibility that Kepler's detection of the exoplanet was bogus, or a so-called false positive.

Taken together, the data boast an error bar of just one percent of the radius of Kepler-93b. The measurements mean that the planet, estimated at about 11,700 miles (18,800 kilometers) in diameter, could be bigger or smaller by about 150 miles (240 kilometers), the approximate distance between Washington, D.C., and Philadelphia.

Spitzer racked up a total of seven transits of Kepler-93b between 2010 and 2011. Three of the transits were snapped using a "peak-up" observational technique. In 2011, Spitzer engineers repurposed the spacecraft's peak-up camera, originally used to point the telescope precisely, to control where light lands on individual pixels within Spitzer's infrared camera.

The upshot of this rejiggering: Ballard and her colleagues were able to cut in half the range of uncertainty of the Spitzer measurements of the exoplanet radius, improving the agreement between the Spitzer and Kepler measurements.

"Ballard and her team have made a major scientific advance while demonstrating the power of Spitzer's new approach to exoplanet observations," said Michael Werner, project scientist for the Spitzer Space Telescope at NASA's Jet Propulsion Laboratory, Pasadena, California.

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.

NASA's Ames Research Center in Moffett Field, California, is responsible for Kepler's ground system development, mission operations and science data analysis. JPL managed Kepler mission development. Ball Aerospace & Technologies Corp. in Boulder, Colorado, developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and was funded by the agency's Science Mission Directorate.

For more information about the Kepler mission, visit:

http://www.nasa.gov/kepler

For more information about Spitzer, visit:

http://spitzer.caltech.edu

http://www.nasa.gov/spitzer

Whitney Clavin

Jet Propulsion Laboratory, Pasadena, Calif.

818-354-4673

whitney.clavin@jpl.nasa.gov


2014-239
Posted by Nelio Inacio at 4:20 PM 0 comments

NASA Seeks Proposals for Commercial Mars Data Relay Satellites

NASA Seeks Proposals for Commercial Mars Data Relay Satellites:

Artist rendering of commercial Mars satellites providing communications back to Earth.
Artist rendering of commercial Mars satellites providing communications back to Earth.
Image Credit: NASA/JPL-Caltech

› Larger image


July 23, 2014

NASA has issued a Request for Information (RFI) to investigate the possibility of using commercial Mars-orbiting satellites to provide telecommunications capabilities for future robotic missions to the Red Planet.

"We are looking to broaden participation in the exploration of Mars to include new models for government and commercial partnerships," said John Grunsfeld, associate administrator of NASA's Science Mission Directorate at the agency's headquarters in Washington. "Depending on the outcome, the new model could be a vital component in future science missions and the path for humans to Mars."

The RFI details possible new business models that would involve NASA contracting to purchase services from a commercial service provider, which would own and operate one or more communication relay orbiters. The solicitation is open to all types of organizations including U.S. industry, universities, nonprofits, NASA centers, and federally funded research and development centers, in addition to U.S. government and international organizations.

NASA is interested in exploring alternative models to sustain and evolve its Mars' communications relay infrastructure to avoid a communications gap in the 2020s. The RFI encourages innovative ideas for cost-effective approaches that provide relay services for existing landers, as well as significantly improving communications performance.

One possible area for improvement is laser or optical communications. NASA successfully demonstrated laser communications technology in October 2013 with its Lunar Atmosphere and Dust Environment Explorer (LADEE) mission. LADEE made history using a pulsed laser beam to transmit data over 239,000 miles from the moon to Earth at a record-breaking download rate of 622 megabits-per-second (Mbps).

Mars landers and rovers currently transmit their science data and other information to Earth either by a direct communication link or via orbiting satellites acting as relay stations. The direct link is severely limited because of mass, volume, and power limits on the rovers. To address these limits, NASA's Mars Exploration Program currently uses relay radios on its Mars science orbiters. The spacecraft carry high-gain antennas and higher power transmitters that provide very high-rate, energy-efficient links between orbiters and surface missions as the obiters pass overhead.

NASA currently is operating two Mars science orbiters with relay capabilities -- Odyssey, launched in 2001, and the Mars Reconnaissance Orbiter (MRO), launched in 2005. These spacecraft enable communication links from the Curiosity and Opportunity rovers on Mars' surface. This approach will continue with the Sept. 21 arrival of the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, and the 2016 arrival of the European Space Agency's ExoMars/Trace Gas Orbiter.

"This Mars relay strategy has been extremely successful in providing the science and engineering data returned from the Martian surface over the past decade," said Lisa May, lead program executive for Mars Exploration Program in Washington.

Because NASA has launched science orbiters to Mars on a steady cadence, the current strategy has been cost effective. However, NASA has no scheduled Mars science orbiters after MAVEN arrives on the Red Planet in the fall. This creates the need to identify cost-effective options to ensure continuity of reliable, high-performance telecommunications relay services for the future.

"Looking ahead, we need to seriously explore the possibility of the commercialization of Mars communications services," said May. "This will offer advantages to NASA, while also providing appropriate return-on-investment to the service provider."

The RFI is for planning and information purposes only. It is not to be construed as a commitment by the government to enter into a contractual agreement, nor will the government pay for information solicited.

To view the complete RFI, visit:

http://go.nasa.gov/1kV6KYj

For more information on NASA Mars missions, visit:

http://www.nasa.gov/mars

For information on the LADEE mission, visit:

http://www.nasa.gov/ladee

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Mars Reconnaissance Orbiter, Mars Odyssey, Opportunity and Curiosity missions. JPL is a division of the California Institute of Technology in Pasadena.

Dwayne Brown

NASA Headquarters, Washington

202-358-1726

dwayne.c.brown@nasa.gov


2014-240
Posted by Nelio Inacio at 4:19 PM 0 comments

NEOWISE Spots a Comet That Looked Like an Asteroid

NEOWISE Spots a Comet That Looked Like an Asteroid:

NEOWISE Spies Activity on Comet Catalina
Comet C/2013 UQ4 (Catalina) appeared to be a highly active comet one day past perihelion on July 7, 2014. Image credit: NASA/JPL-Caltech
› Full image and caption


July 23, 2014

Comet C/2013 UQ4 (Catalina) has been observed by NASA's Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) spacecraft just one day after passing through its closest approach to the sun. The comet glows brightly in infrared wavelengths, with a dust tail streaking more than 62,000 miles (100,000 kilometers) across the sky. Its spectacular activity is driven by the vaporization of ice that has been preserved from the time of planet formation 4.5 billion years ago.

"The tail forms a faint fan as the smaller dust particles are more easily pushed away from the sun by the radiation pressure of the sunlight," said James Bauer, researcher at NASA's Jet Propulsion Laboratory in Pasadena, California.

C/2013 UQ4 takes more than 450 years to orbit the sun once and spends most of its time far away at very low temperatures. Its orbit is also retrograde, which means that the comet moves around the sun in the opposite direction to the planets and asteroids.

The comet was originally thought to be an asteroid, as it appeared inactive when discovered by the Catalina Sky Survey on October 23, 2013. NEOWISE also observed the comet to be inactive on New Year's Eve, 2013, but since then the comet has become highly active, allowing astronomers around the world to observe it. The comet's activity should decline as it once again returns to the cold recesses of space.

NASA's Jet Propulsion Laboratory manages the NEOWISE mission for NASA's Science Mission Directorate in Washington. The Space Dynamics Laboratory in Logan, Utah, built the science instrument. Ball Aerospace & Technologies Corp. of Boulder, Colo., built the spacecraft. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. For more information about NEOWISE, visit:

http://www.nasa.gov/neowise

Elizabeth Landau

818-354-6425

Jet Propulsion Laboratory, Pasadena, Calif.

elizabeth.landau@jpl.nasa.gov


2014-241
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Tuesday, July 22, 2014

Comet Found Hiding in Plain Sight

Comet Found Hiding in Plain Sight:

Spitzer Spies a Comet Coma and Tail
With the help of NASA's Spitzer Space Telescope, astronomers have discovered that what was thought to be a large asteroid called Don Quixote is in fact a comet. Image credit: NASA/JPL-Caltech/DLR/NAU
› Full image and caption

September 10, 2013

For 30 years, a large near-Earth asteroid wandered its lone, intrepid path, passing before the scrutinizing eyes of scientists armed with telescopes while keeping something to itself. The object, known as Don Quixote, whose journey stretches to the orbit of Jupiter, now appears to be a comet.


The discovery resulted from an ongoing project coordinated by researchers at Northern Arizona University, Flagstaff, Ariz., using NASA's Spitzer Space Telescope. Through a lot of focused attention and a little luck, they found evidence of comet activity, which had evaded detection for three decades.


The results show that Don Quixote is not, in fact, a dead comet, as previously believed, but it has a faint coma and tail. In fact, this object, the third-biggest near-Earth asteroid known, skirts Earth with an erratic, extended orbit and is "sopping wet," said David Trilling of Northern Arizona University, with large deposits of carbon dioxide and presumably water ice. Don Quixote is about 11 miles (18 kilometers) long.


"This discovery of carbon dioxide emission from Don Quixote required the sensitivity and infrared wavelengths of the Spitzer telescope and would not have been possible using telescopes on the ground," said Michael Mommert, who conducted the research at the German Aerospace Center, Berlin, before moving to Northern Arizona University. This discovery implies that carbon dioxide and water ice might be present on other near-Earth asteroids, as well.


The implications have less to do with a potential impact, which is extremely unlikely in this case, and more with "the origins of water on Earth," Trilling said. Impacts with comets like Don Quixote over geological time may be the source of at least some of it, and the amount on Don Quixote represents about 100 billion tons of water -- roughly the same amount that can be found in Lake Tahoe, Calif.


Mommert presented the results at the European Planetary Science Congress in London on Sept. 10.


Read the full news release from Northern Arizona University at http://news.nau.edu/nau-led-teams-discovers-comet-hiding-in-plain-sight/ .


NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. 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 http://spitzer.caltech.edu and http://www.nasa.gov/spitzer .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


2013-274
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'La Nada' Climate Pattern Lingers in the Pacific

'La Nada' Climate Pattern Lingers in the Pacific:

The latest image of sea surface heights in the Pacific Ocean from NASA's Jason-2 satellite
The latest image of sea surface heights in the Pacific Ocean from NASA's Jason-2 satellite shows that the equatorial Pacific Ocean is now in its 16th month of being locked in what some call a neutral, or "La Nada" state.
Image credit: NASA-JPL/Caltech/Ocean Surface Topography Team

› Full image and caption

September 09, 2013

UPDATE - SEPT. 10: After publication of this image on Sept. 9, a small error was discovered in the original processing of the data that were used to generate the Aug. 27, 2013 Jason-2 image. The image has been updated accordingly. The data used to generate the reprocessed image are the same, and the discussion and analysis of the data in the news story below remains unchanged.


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New remote sensing data from NASA's Jason-2 satellite show near-normal sea-surface height conditions across the equatorial Pacific Ocean. This neutral, or "La Nada" event, has stubbornly persisted for 16 months, since spring 2012. Models suggest this pattern will continue through the spring of 2014, according to the National Weather Service's Climate Prediction Center.


"Without an El Niño or La Niña signal present, other, less predictable, climatic factors will govern fall, winter and spring weather conditions," said climatologist Bill Patzert of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Long-range forecasts are most successful during El Niño and La Niña episodes. The 'in between' ocean state, La Nada, is the dominant condition, and is frustrating for long-range forecasters. It's like driving without a decent road map -- it makes forecasting difficult."


The near-normal conditions are shown in a new image (as areas shaded in green), based on the average of 10 days of data centered on Aug. 27, 2013. The image is available at: http://www.jpl.nasa.gov/spaceimages/details.php?id=pia17454 .


For the past several decades, about half of all years have experienced La Nada conditions, compared to about 20 percent for El Niño and 30 percent for La Niña.


Patzert noted that some of the wettest and driest winters occur during La Nada periods.


"Neutral infers something benign, but in fact if you look at these La Nada years when neither El Niño nor La Niña are present, they can be the most volatile and punishing. As an example, the continuing, deepening drought in the American West is far from 'neutral,'" he said.


The height of the sea water relates, in part, to its temperature, and thus is an indicator of the amount of heat stored in the ocean below. As the ocean warms, its level rises; as it cools, its level falls. Yellow and red areas indicate where the waters are relatively warmer and have expanded above normal sea level, while green (which dominates in this image) indicates near-normal sea level, and blue and purple areas show where the waters are relatively colder and sea level is lower than normal. Above-normal height variations along the equatorial Pacific indicate El Niño conditions, while below-normal height variations indicate La Niña conditions. The temperature of the upper ocean can have a significant influence on weather patterns and climate. For a more detailed explanation of what this type of image means, visit: http://sealevel.jpl.nasa.gov/science/elninopdo/latestdata/.


This latest image highlights the processes that occur on time scales of more than a year, but usually less than 10 years, such as El Niño and La Niña. These processes are known as the interannual ocean signal. To show that signal, scientists refined data for this image by removing trends over the past 20 years, seasonal variations and time-averaged signals of large-scale ocean circulation.


NASA scientists will continue to monitor this persistent La Nada event to see what the Pacific Ocean has in store next for the world's climate.


The comings and goings of El Niño, La Niña and La Nada are part of the long-term, evolving state of global climate, for which measurements of sea surface height are a key indicator. Jason-2 is a joint effort between NASA, the National Oceanic and Atmospheric Administration (NOAA), the French Space Agency Centre National d'Etudes Spatiales (CNES) and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). JPL manages the U.S. portion of Jason-2 for NASA's Science Mission Directorate, Washington, D.C.
In early 2015, NASA and its international partners CNES, NOAA and EUMETSAT will launch Jason-3, which will extend the timeline of ocean surface topography measurements begun by the Topex/Poseidon and Jason 1 and 2 satellites. Jason-3 will make highly detailed measurements of sea level on Earth to gain insight into ocean circulation and climate change.


For more on NASA's satellite altimetry programs, visit: http://sealevel.jpl.nasa.gov.

Alan Buis 818-354-0474

Jet Propulsion Laboratory, Pasadena, Calif.

alan.buis@jpl.nasa.gov


2013-272
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Coldest Brown Dwarfs Blur Star, Planet Lines

Coldest Brown Dwarfs Blur Star, Planet Lines:

Brown Dwarf Backyardigans
The locations of brown dwarfs discovered by NASA's Wide-field Infrared Survey Explorer, or WISE, and mapped by NASA's Spitzer Space Telescope, are shown in this diagram. The view is from a vantage point about 100 light-years away from the sun, looking back toward the constellation Orion. Image credit: NASA/JPL-Caltech
› Full image and caption

September 05, 2013

In 2011, astronomers on the hunt for the coldest star-like celestial bodies discovered a new class of such objects using NASA's Wide-Field Infrared Survey Explorer (WISE) space telescope. But until now, no one knew exactly how cool the bodies' surfaces really are. In fact, some evidence suggested they could be at room temperature.


A new study using data from NASA's Spitzer Space Telescope shows that while these so-called brown dwarfs are indeed the coldest known free-floating celestial bodies, they are warmer than previously thought, with surface temperatures ranging from about 250 to 350 degrees Fahrenheit (125 to 175 degrees Celsius). By comparison, the sun has a surface temperature of about 10,340 degrees Fahrenheit (5,730 degrees Celsius).


To reach these surface temperatures after cooling for billions of years, these objects would have to have masses of only five to 20 times that of Jupiter. Unlike the sun, the only source of energy for these coldest of brown dwarfs is from their gravitational contraction, which depends directly on their mass. The sun is powered by the conversion of hydrogen to helium; these brown dwarfs are not hot enough for this type of "nuclear burning" to occur.


The findings help researchers understand how planets and stars form.


"If one of these objects were found orbiting a star, there is a good chance that it would be called a planet," said Trent Dupuy, a Hubble Fellow at the Harvard-Smithsonian Center for Astrophysics and a co-author of the study, appearing online Sept. 5 in the journal Science Express. But because they probably formed on their own and not in a planet-forming disk orbiting a more massive star, astronomers still call these objects brown dwarfs even if their mass is of planetary size.


Characterizing these cold brown dwarfs is challenging because they emit most of their light at infrared wavelengths and are very faint due to their small size and low temperature.


To get accurate temperatures, astronomers need to know the distances to these objects. "We wanted to find out if they were colder, fainter and nearby, or if they were warmer, brighter and more distant," explains Dupuy.


Using Spitzer, the team determined that the brown dwarfs in question are located at distances 20 to 50 light-years away.


To determine the distances to these objects, the team measured their parallax -- the apparent change in position against background stars over time. As Spitzer orbits the sun, its perspective changes and nearby objects appear to shift back and forth slightly. The same effect occurs if you hold up a finger in front of your face and close one eye and then the other. The position of your finger seems to shift when viewed against the distant background.


But even for these relatively nearby brown dwarfs, the parallax motion is small. "To be able to determine accurate distances, our measurements had to be the same precision as knowing the position of a firefly to within 1 inch (2.5 centimeters) from 200 miles (320 kilometers) away," explained Adam Kraus, professor at the University of Texas at Austin and the study's other co-author.


The new data also present new puzzles to astronomers who study cool, planet-like atmospheres. Unlike warmer brown dwarfs and stars, the observable properties of these objects don't seem to correlate as strongly with temperature. This suggests increased roles for other factors, such as convective mixing, in driving the chemistry at the surface.


This study examined the initial sample of the coldest brown dwarfs discovered in the WISE survey data. Additional objects discovered in the past two years remain to be studied, and scientists hope they will shed light on some of these outstanding issues.


NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. 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 http://spitzer.caltech.edu and http://www.nasa.gov/spitzer.

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov

2013-271
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How Do We Know When Voyager Reaches Interstellar Space?

How Do We Know When Voyager Reaches Interstellar Space?:

This artist's concept shows NASA's Voyager spacecraft against a backdrop of stars.
You Are Here, Voyager: This artist's concept puts huge solar system distances in perspective. The scale bar is measured in astronomical units (AU), with each set distance beyond 1 AU representing 10 times the previous distance. Each AU is equal to the distance from the sun to the Earth. It took from 1977 to 2013 for Voyager 1 to reach the edge of interstellar space.
Image Credit:
NASA/JPL-Caltech
› Full image and caption

September 12, 2013

Whether and when NASA's Voyager 1 spacecraft, humankind's most distant object, broke through to interstellar space, the space between stars, has been a thorny issue. For the last year, claims have surfaced every few months that Voyager 1 has "left our solar system." Why has the Voyager team held off from saying the craft reached interstellar space until now?


"We have been cautious because we're dealing with one of the most important milestones in the history of exploration," said Voyager Project Scientist Ed Stone of the California Institute of Technology in Pasadena. "Only now do we have the data -- and the analysis -- we needed."


Basically, the team needed more data on plasma, which is ionized gas, the densest and slowest moving of charged particles in space. (The glow of neon in a storefront sign is an example of plasma.) Plasma is the most important marker that distinguishes whether Voyager 1 is inside the solar bubble, known as the heliosphere, which is inflated by plasma that streams outward from our sun, or in interstellar space and surrounded by material ejected by the explosion of nearby giant stars millions of years ago. Adding to the challenge: they didn't know how they'd be able to detect it.


"We looked for the signs predicted by the models that use the best available data, but until now we had no measurements of the plasma from Voyager 1," said Stone.


Scientific debates can take years, even decades to settle, especially when more data are needed. It took decades, for instance, for scientists to understand the idea of plate tectonics, the theory that explains the shape of Earth's continents and the structure of its sea floors. First introduced in the 1910s, continental drift and related ideas were controversial for years. A mature theory of plate tectonics didn't emerge until the 1950s and 1960s. Only after scientists gathered data showing that sea floors slowly spread out from mid-ocean ridges did they finally start accepting the theory. Most active geophysicists accepted plate tectonics by the late 1960s, though some never did.


Voyager 1 is exploring an even more unfamiliar place than our Earth's sea floors -- a place more than 11 billion miles (17 billion kilometers) away from our sun. It has been sending back so much unexpected data that the science team has been grappling with the question of how to explain all the information. None of the handful of models the Voyager team uses as blueprints have accounted for the observations about the transition between our heliosphere and the interstellar medium in detail. The team has known it might take months, or longer, to understand the data fully and draw their conclusions.


"No one has been to interstellar space before, and it's like traveling with guidebooks that are incomplete," said Stone. "Still, uncertainty is part of exploration. We wouldn't go exploring if we knew exactly what we'd find."


The two Voyager spacecraft were launched in 1977 and, between them, had visited Jupiter, Saturn, Uranus and Neptune by 1989. Voyager 1's plasma instrument, which measures the density, temperature and speed of plasma, stopped working in 1980, right after its last planetary flyby. When Voyager 1 detected the pressure of interstellar space on our heliosphere in 2004, the science team didn't have the instrument that would provide the most direct measurements of plasma. Instead, they focused on the direction of the magnetic field as a proxy for source of the plasma. Since solar plasma carries the magnetic field lines emanating from the sun and interstellar plasma carries interstellar magnetic field lines, the directions of the solar and interstellar magnetic fields were expected to differ.


Most models told the Voyager science team to expect an abrupt change in the magnetic field direction as Voyager switched from the solar magnetic field lines inside our solar bubble to those in interstellar space. The models also said to expect the levels of charged particles originating from inside the heliosphere to drop and the levels of galactic cosmic rays, which originate outside the heliosphere, to jump.


In May 2012, the number of galactic cosmic rays made its first significant jump, while some of the inside particles made their first significant dip. The pace of change quickened dramatically on July 28, 2012. After five days, the intensities returned to what they had been. This was the first taste of a new region, and at the time Voyager scientists thought the spacecraft might have briefly touched the edge of interstellar space.


By Aug. 25, when, as we now know, Voyager 1 entered this new region for good, all the lower-energy particles from inside zipped away. Some inside particles dropped by more than a factor of 1,000 compared to 2004. The levels of galactic cosmic rays jumped to the highest of the entire mission. These would be the expected changes if Voyager 1 had crossed the heliopause, which is the boundary between the heliosphere and interstellar space. However, subsequent analysis of the magnetic field data revealed that even though the magnetic field strength jumped by 60 percent at the boundary, the direction changed less than 2 degrees. This suggested that Voyager 1 had not left the solar magnetic field and had only entered a new region, still inside our solar bubble, that had been depleted of inside particles.


Then, in April 2013, scientists got another piece of the puzzle by chance. For the first eight years of exploring the heliosheath, which is the outer layer of the heliosphere, Voyager's plasma wave instrument had heard nothing. But the plasma wave science team, led by Don Gurnett and Bill Kurth at the University of Iowa, Iowa City, had observed bursts of radio waves in 1983 to 1984 and again in 1992 to 1993. They deduced these bursts were produced by the interstellar plasma when a large outburst of solar material would plow into it and cause it to oscillate. It took about 400 days for such solar outbursts to reach interstellar space, leading to an estimated distance of 117 to 177 AU (117 to 177 times the distance from the sun to the Earth) to the heliopause. They knew, though, that they would be able to observe plasma oscillations directly once Voyager 1 was surrounded by interstellar plasma.


Then on April 9, 2013, it happened: Voyager 1's plasma wave instrument picked up local plasma oscillations. Scientists think they probably stemmed from a burst of solar activity from a year before, a burst that has become known as the St. Patrick's Day Solar Storms. The oscillations increased in pitch through May 22 and indicated that Voyager was moving into an increasingly dense region of plasma. This plasma had the signatures of interstellar plasma, with a density more than 40 times that observed by Voyager 2 in the heliosheath.


Gurnett and Kurth began going through the recent data and found a fainter, lower-frequency set of oscillations from Oct. 23 to Nov. 27, 2012. When they extrapolated back, they deduced that Voyager had first encountered this dense interstellar plasma in August 2012, consistent with the sharp boundaries in the charged particle and magnetic field data on August 25.


Stone called three meetings of the Voyager team. They had to decide how to define the boundary between our solar bubble and interstellar space and how to interpret all the data Voyager 1 had been sending back. There was general agreement Voyager 1 was seeing interstellar plasma, based on the results from Gurnett and Kurth, but the sun still had influence. One persisting sign of solar influence, for example, was the detection of outside particles hitting Voyager from some directions more than others. In interstellar space, these particles would be expected to hit Voyager uniformly from all directions.


"Now that we had actual measurements of the plasma environment - by way of an unexpected outburst from the sun - we had to reconsider why there was still solar influence on the magnetic field and plasma in interstellar space," Stone said. "The path to interstellar space has been a lot more complicated than we imagined."


Stone discussed with the Voyager science group whether they thought Voyager 1 had crossed the heliopause. What should they call the region were Voyager 1 is?


"In the end, there was general agreement that Voyager 1 was indeed outside in interstellar space," Stone said. "But that location comes with some disclaimers - we're in a mixed, transitional region of interstellar space. We don't know when we'll reach interstellar space free from the influence of our solar bubble."


So, would the team say Voyager 1 has left the solar system? Not exactly - and that's part of the confusion. Since the 1960s, most scientists have defined our solar system as going out to the Oort Cloud, where the comets that swing by our sun on long timescales originate. That area is where the gravity of other stars begins to dominate that of the sun. It will take about 300 years for Voyager 1 to reach the inner edge of the Oort Cloud and possibly about 30,000 years to fly beyond it. Informally, of course, "solar system" typically means the planetary neighborhood around our sun. Because of this ambiguity, the Voyager team has lately favored talking about interstellar space, which is specifically the space between each star's realm of plasma influence.


"What we can say is Voyager 1 is bathed in matter from other stars," Stone said. "What we can't say is what exact discoveries await Voyager's continued journey. No one was able to predict all of the details that Voyager 1 has seen. So we expect more surprises."


Voyager 1, which is working with a finite power supply, has enough electrical power to keep operating the fields and particles science instruments through at least 2020, which will mark 43 years of continual operation. At that point, mission managers will have to start turning off these instruments one by one to conserve power, with the last one turning off around 2025.


Voyager 1 will continue sending engineering data for a few more years after the last science instrument is turned off, but after that it will be sailing on as a silent ambassador. In about 40,000 years, it will be closer to the star AC +79 3888 than our own sun. (AC +79 3888 is traveling toward us faster than we are traveling towards it, so while Alpha Centauri is the next closest star now, it won't be in 40,000 years.) And for the rest of time, Voyager 1 will continue orbiting around the heart of the Milky Way galaxy, with our sun but a tiny point of light among many.


The Voyager spacecraft were built and continue to be operated by NASA's Jet Propulsion Laboratory, in Pasadena, Calif. Caltech manages JPL for NASA. The Voyager missions are a part of NASA's Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate at NASA Headquarters in Washington.


For more information about Voyager, visit: http://www.nasa.gov/voyager and http://voyager.jpl.nasa.gov.

Jia-Rui Cook 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov


2013-278
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NASA Spacecraft Embarks on Historic Journey Into Interstellar Space

NASA Spacecraft Embarks on Historic Journey Into Interstellar Space:

Voyager 1 Entering Interstellar Space
The Space Between: This artist's concept shows the Voyager 1 spacecraft entering the space between stars. Interstellar space is dominated by plasma, ionized gas (illustrated here as brownish haze), that was thrown off by giant stars millions of years ago. Image credit: NASA/JPL-Caltech
› Full image and caption

September 12, 2013

PASADENA, Calif. -- NASA's Voyager 1 spacecraft officially is the first human-made object to venture into interstellar space. The 36-year-old probe is about 12 billion miles (19 billion kilometers) from our sun.


New and unexpected data indicate Voyager 1 has been traveling for about one year through plasma, or ionized gas, present in the space between stars. Voyager is in a transitional region immediately outside the solar bubble, where some effects from our sun are still evident. A report on the analysis of this new data, an effort led by Don Gurnett and the plasma wave science team at the University of Iowa, Iowa City, is published in Thursday's edition of the journal Science.


"Now that we have new, key data, we believe this is mankind's historic leap into interstellar space," said Ed Stone, Voyager project scientist based at the California Institute of Technology, Pasadena. "The Voyager team needed time to analyze those observations and make sense of them. But we can now answer the question we've all been asking -- 'Are we there yet?' Yes, we are."


Voyager 1 first detected the increased pressure of interstellar space on the heliosphere, the bubble of charged particles surrounding the sun that reaches far beyond the outer planets, in 2004. Scientists then ramped up their search for evidence of the spacecraft's interstellar arrival, knowing the data analysis and interpretation could take months or years.


Voyager 1 does not have a working plasma sensor, so scientists needed a different way to measure the spacecraft's plasma environment to make a definitive determination of its location. A coronal mass ejection, or a massive burst of solar wind and magnetic fields, that erupted from the sun in March 2012 provided scientists the data they needed. When this unexpected gift from the sun eventually arrived at Voyager 1's location 13 months later, in April 2013, the plasma around the spacecraft began to vibrate like a violin string. On April 9, Voyager 1's plasma wave instrument detected the movement. The pitch of the oscillations helped scientists determine the density of the plasma. The particular oscillations meant the spacecraft was bathed in plasma more than 40 times denser than what they had encountered in the outer layer of the heliosphere. Density of this sort is to be expected in interstellar space.


The plasma wave science team reviewed its data and found an earlier, fainter set of oscillations in October and November 2012. Through extrapolation of measured plasma densities from both events, the team determined Voyager 1 first entered interstellar space in August 2012.


"We literally jumped out of our seats when we saw these oscillations in our data -- they showed us the spacecraft was in an entirely new region, comparable to what was expected in interstellar space, and totally different than in the solar bubble," Gurnett said. "Clearly we had passed through the heliopause, which is the long-hypothesized boundary between the solar plasma and the interstellar plasma."


The new plasma data suggested a timeframe consistent with abrupt, durable changes in the density of energetic particles that were first detected on Aug. 25, 2012. The Voyager team generally accepts this date as the date of interstellar arrival. The charged particle and plasma changes were what would have been expected during a crossing of the heliopause.


"The team's hard work to build durable spacecraft and carefully manage the Voyager spacecraft's limited resources paid off in another first for NASA and humanity," said Suzanne Dodd, Voyager project manager, based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We expect the fields and particles science instruments on Voyager will continue to send back data through at least 2020. We can't wait to see what the Voyager instruments show us next about deep space."


Voyager 1 and its twin, Voyager 2, were launched 16 days apart in 1977. Both spacecraft flew by Jupiter and Saturn. Voyager 2 also flew by Uranus and Neptune. Voyager 2, launched before Voyager 1, is the longest continuously operated spacecraft. It is about 9.5 billion miles (15 billion kilometers) away from our sun.


Voyager mission controllers still talk to or receive data from Voyager 1 and Voyager 2 every day, though the emitted signals are currently very dim, at about 23 watts -- the power of a refrigerator light bulb. By the time the signals get to Earth, they are a fraction of a billion-billionth of a watt. Data from Voyager 1's instruments are transmitted to Earth typically at 160 bits per second, and captured by 34- and 70-meter NASA Deep Space Network stations. Traveling at the speed of light, a signal from Voyager 1 takes about 17 hours to travel to Earth. After the data are transmitted to JPL and processed by the science teams, Voyager data are made publicly available.


"Voyager has boldly gone where no probe has gone before, marking one of the most significant technological achievements in the annals of the history of science, and adding a new chapter in human scientific dreams and endeavors," said John Grunsfeld, NASA's associate administrator for science in Washington. "Perhaps some future deep space explorers will catch up with Voyager, our first interstellar envoy, and reflect on how this intrepid spacecraft helped enable their journey."


Scientists do not know when Voyager 1 will reach the undisturbed part of interstellar space where there is no influence from our sun. They also are not certain when Voyager 2 is expected to cross into interstellar space, but they believe it is not very far behind.


JPL built and operates the twin Voyager spacecraft. The Voyagers Interstellar Mission is a part of NASA's Heliophysics System Observatory, sponsored by the Heliophysics Division of NASA's Science Mission Directorate in Washington. NASA's Deep Space Network, managed by JPL, is an international network of antennas that supports interplanetary spacecraft missions and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected Earth-orbiting missions.


The cost of the Voyager 1 and Voyager 2 missions -- including launch, mission operations and the spacecraft's nuclear batteries, which were provided by the Department of Energy -- is about $988 million through September.


For a sound file of the oscillations detected by Voyager in interstellar space, animations and other information, visit: http://www.nasa.gov/voyager and http://www.jpl.nasa.gov/interstellarvoyager/ .


For an image of the radio signal from Voyager 1 on Feb. 21 by the National Radio Astronomy Observatory's Very Long Baseline Array, which links telescopes from Hawaii to St. Croix, visit:
http://www.nrao.edu .

Jia-Rui C. Cook/D.C. Agle 818-354-0850/818-393-9011

Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov


Dwayne Brown 202-358-1726

Headquarters, Washington

dwayne.c.brown@nasa.gov


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NASA News Conference Today to Discuss Voyager Spacecraft

NASA News Conference Today to Discuss Voyager Spacecraft:

Voyager in Space
This artist's concept shows NASA's Voyager spacecraft against a backdrop of stars. Image credit: NASA/JPL-Caltech
› Full image and caption

September 11, 2013

PASADENA, Calif. - NASA will host a news conference today at 11 a.m. PDT (2 p.m. EDT), to discuss NASA's Voyager mission. It is related to a paper to be published in the journal Science, which is embargoed until 11 a.m. PDT (2 p.m. EDT).


The briefing will be held at NASA Headquarters in Washington and air live on NASA Television and the agency's website.


During the news conference, the public may send questions via Twitter to #AskNASA.


For NASA TV streaming video, scheduling and downlink information, visit: http://www.nasa.gov/ntv .


The event will also be streamed live on Ustream at: http://www.ustream.tv/nasajpl2 .


For information about the Voyager mission, visit: http://www.nasa.gov/voyager .

DC Agle/Jia-Rui Cook 818-393-9011/818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

agle@jpl.nasa.gov/jccook@jpl.nasa.gov


Dwayne Brown 202-358-1726

NASA Headquarters, Washington

dwayne.c.brown@nasa.gov


2013-276b
Posted by Nelio Inacio at 6:41 PM 0 comments
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