Cassini Heading to Titan after Tagging Enceladus

NASA's Cassini spacecraft is on its way to a flyby of Saturn's largest moon, Titan, after capturing some stunning images of Enceladus. One view shows the hazy outline of Titan behind Saturn's rings, with the dark curve of Enceladus at the bottom.

In other images, Enceladus put its craggy face forward, exhibiting some of the fractures and cratering that have made the Saturnian moon a favorite of both planetary scientists and outer-planet mission groupies. A view of Enceladus' terminator was taken by NASA's Cassini spacecraft on May 18 from approximately 75,000 kilometers (46,500 miles) away.

Cassini sent back numerous images May 18, 2010, as it finished the first leg of its planned double flyby. Cassini passed within about 435 kilometers (270 miles) of the Enceladus surface.

Cassini is heading toward Titan for a flyby that occurs in the late evening May 19 Pacific time, which is in the early hours of May 20 UTC. Because of a fortuitous cosmic alignment, Cassini can catch glimpses of these two contrasting worlds within less than 48 hours, with no maneuver in between.

The main scientific goal at Enceladus was to watch the sun play peek-a-boo behind the water-rich plume emanating from the moon's south polar region. Scientists using the ultraviolet imaging spectrograph will be able to use the flickering light to measure whether there is molecular nitrogen in the plume. Ammonia has already been detected in the plume, and scientists know heat can decompose ammonia into nitrogen molecules. Determining the amount of molecular nitrogen in the plume will give scientists clues about thermal processing in the moon's interior.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL.

More raw images from the Enceladus flyby, dubbed "E10," are available at: http://saturn.jpl.nasa.gov/photos/raw/

More information on the Titan flyby, dubbed "T68," is online at: http://saturn.jpl.nasa.gov/mission/flybys/titan20100520/

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Cassini Double Play: Enceladus and Titan

About a month and a half after its last double flyby, NASA's Cassini spacecraft will be turning another double play this week, visiting the geyser moon Enceladus and the hazy moon Titan. The alignment of the moons means that Cassini can catch glimpses of these two contrasting worlds within less than 48 hours, with no maneuver in between.

Cassini will make its closest approach to Enceladus late at night on May 17 Pacific time, which is in the early hours of May 18 UTC. The spacecraft will pass within about 435 kilometers (270 miles) of the moon's surface.

The main scientific goal at Enceladus will be to watch the sun play peekaboo behind the water-rich plume emanating from the moon's south polar region. Scientists using the ultraviolet imaging spectrograph will be able to use the flickering light to measure whether there is molecular nitrogen in the plume. Ammonia has already been detected in the plume and scientists know heat can decompose ammonia into nitrogen molecules. Determining the amount of molecular nitrogen in the plume will give scientists clues about thermal processing in the moon's interior.

The second of Cassini's two flybys is an encounter with Titan. The closest approach will take place in the late evening May 19 Pacific time, which is in the early hours of May 20 UTC. The spacecraft will fly to within 1,400 kilometers (750 miles) of the surface.

Cassini will primarily be doing radio science during this pass to detect the subtle variations in the gravitational tug on the spacecraft by Titan, which is 25 percent larger in volume than the planet Mercury. Analyzing the data will help scientists learn whether Titan has a liquid ocean under its surface and get a better picture of its internal structure. The composite infrared spectrometer will also get its southernmost pass for thermal data to fill out its temperature map of the smoggy moon.

Cassini has made four previous double flybys and one more is planned in the years ahead.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL.

More information on the Enceladus flyby, dubbed "E10," is available at: http://saturn.jpl.nasa.gov/mission/flybys/enceladus20100518/

More information on the Titan flyby, dubbed "T68," is available at: http://saturn.jpl.nasa.gov/mission/flybys/titan20100520/

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Mars Image Takes Earth Photo Event to a New World

When some Mars explorers learned of plans for a worldwide photography event combining shots taken from thousands of different locations on May 2, 2010, they figured, "Why just one world?"

A New York Times photography blog, Lens, proposed the event and has received more than 12,000 images from around the world. Plus one from a rover on Mars.

The inspiration came from a suggestion by Emily Lakdawalla, science and technology coordinator for The Planetary Society in Pasadena, Calif.

Astronomer Jim Bell of Cornell University in Ithaca, N.Y., lead scientist for the panoramic camera (Pancam) on NASA's Mars Exploration Rover Opportunity, suggested that the rover team include commands for Opportunity to take multiple exposures late in the Martian afternoon on May 2. The resulting scene extends from the rover's own deck to ochre sky above the horizon more than 3 kilometers (2 miles) away. Dramatically shaded ripples of windblown sand reach toward the distant horizon.

The Opportunity image is highlighted at the Lens blog at: http://lens.blogs.nytimes.com/2010/05/12/readers-19/. The entire gallery of "Moment in Time" images, the vast majority from Planet Earth, is online at: http://www.nytimes.com/interactive/2010/05/03/blogs/a-moment-in-time.html#/4bdd9784db799a656b0002e9.

The Lens blog proposed that photos be shot at 1500 Universal Time (UT, or Greenwich Mean Time) on May 2 from locations around the world. For logistical reasons, the rover instead took the pictures just before 1500 "local true solar time" on Mars, which was about 1115 UT on May 2 on Earth. Shortly afterwards, the rover transmitted the image data to NASA's Mars Odyssey orbiter, which relayed them to Earth.

"It wasn't until about 1500 Universal Time on Earth that we could actually see the images and combine them into a mosaic," Bell said. "So we shot the mosaic on Mars at around 1500 local Mars time and received and processed the image on Earth around 1500 Universal Time. In those respects, we hope that our entry is consistent with the spirit of the rules, making this a truly interplanetary event."

The Jet Propulsion Laboratory in Pasadena, Calif., manages the Mars Exploration Rovers, Spirit and Opportunity, for NASA's Science Mission Directorate, Washington. JPL is a division of the California Institute of Technology in Pasadena.

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Asteroid Caught Marching Across Tadpole Nebula

A new infrared image from NASA's Wide-field Infrared Survey Explorer, or WISE, showcases the Tadpole nebula, a star-forming hub in the Auriga constellation about 12,000 light-years from Earth.

As WISE scanned the sky, capturing this mosaic of stitched-together frames, it happened to catch an asteroid in our solar system passing by. The asteroid, called 1719 Jens, left tracks across the image, seen as a line of yellow-green dots in the boxes near center. A second asteroid, called 1992 UZ5, was also observed cruising by, as highlighted in the boxes near the upper left (the larger boxes are blown-up versions of the smaller ones).

But that's not all that WISE caught in this busy image -- two satellites orbiting above WISE (highlighted in the ovals) streak through the image, appearing as faint green trails. The apparent motion of asteroids is slower than satellites because asteroids are much more distant, and thus appear as dots that move from one WISE frame to the next, rather than streaks in a single frame.

This Tadpole region is chock full of stars as young as only a million years old -- infants in stellar terms -- and masses over 10 times that of our sun. It is called the Tadpole nebula because the masses of hot, young stars are blasting out ultraviolet radiation that has etched the gas into two tadpole-shaped pillars, called Sim 129 and Sim 130. These "tadpoles" appear as the yellow squiggles near the center of the frame. The knotted regions at their heads are likely to contain new young stars. WISE's infrared vision is helping to ferret out hidden stars such as these.

The 1719 Jens asteroid, discovered in 1950, orbits in the main asteroid belt between Mars and Jupiter. The space rock, which has a diameter of 19 kilometers (12 miles), rotates every 5.9 hours and orbits the sun every 4.3 years.

Twenty-five frames of the region, taken at all four of the wavelengths detected by WISE, were combined into this one image. The space telescope caught 1719 Jens in 11 successive frames. Infrared light of 3.4 microns is color-coded blue: 4.6-micron light is cyan; 12-micron-light is green; and 22-micron light is red.

WISE is an all-sky survey, snapping pictures of the whole sky, including everything from asteroids to stars to powerful, distant galaxies.

JPL manages WISE for NASA's Science Mission Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. 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.

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Final Attempts to Hear from Mars Phoenix Scheduled

From May 17 to 21, NASA's Mars Odyssey orbiter will conduct a fourth and final campaign to check on whether the Phoenix Mars Lander has come back to life.

During that period, Odyssey will listen for a signal from Phoenix during 61 flights over the lander's site on far-northern Mars. The orbiter detected no transmission from the lander in earlier campaigns totaling 150 overflights in January, February and April.

In 2008, Phoenix completed its three-month mission studying Martian ice, soil and atmosphere. The lander worked for five months before reduced sunlight caused energy to become insufficient to keep the lander functioning. The solar-powered robot was not designed to survive through the dark and cold conditions of a Martian arctic winter. However, in case it did, NASA has used Odyssey to listen for the signals that Phoenix would transmit if abundant spring sunshine revived the lander.

Northern Mars will experience its maximum-sunshine day, the summer solstice, on May 12 (Eastern Time; May 13, Universal Time), so the sun will be higher in the sky above Phoenix during the fourth listening campaign than during any of the prior ones. Still, expectations of hearing from the lander remain low.

"To be thorough, we decided to conduct this final session around the time of the summer solstice, during the best thermal and power conditions for Phoenix," said Chad Edwards, chief telecommunications engineer for the Mars Exploration Program at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The Phoenix mission is led by Principal Investigator Peter H. Smith of the University of Arizona, Tucson, with project management at JPL and development partnership with Lockheed Martin Space Systems. JPL, a division of the California Institute of Technology in Pasadena, also manages the Odyssey project in an operational partnership with Lockheed Martin.

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Herschel Finds a Hole in Space

The Herschel Space Observatory has made an unexpected discovery: a gaping hole in the clouds surrounding a batch of young stars. The hole has provided astronomers with a surprising glimpse into the end of the star-forming process.

Stars are born hidden in dense clouds of dust and gas, which can now be studied in remarkable detail with Herschel, a European Space Agency mission with important NASA participation. Although jets and winds of gas have been seen streaming from young stars in the past, it has always been a mystery exactly how a star uses the jets to blow away its surroundings and emerge from its birth cloud. For the first time, Herschel may be seeing an unexpected step in this process.

A cloud of bright reflective gas known to astronomers as NGC 1999 sits next to a black patch of sky. For most of the 20th century, such black patches were known to be dense clouds of dust and gas that block light from passing through.

When Herschel looked in its direction to study nearby young stars, astronomers were surprised to see the cloud continued to look black, which shouldn't have been the case. Herschel's infrared eyes are designed to see into such clouds. Either the cloud was immensely dense or something was wrong.

Investigating further using ground-based telescopes, astronomers found the same story no matter how they looked: this patch looks black not because it is a dense pocket of gas but because it is truly empty. Something has blown a hole right through the cloud.

"No one has ever seen a hole like this," says Tom Megeath of the University of Toledo, Ohio, the principal investigator of the research. "It's as surprising as knowing you have worms tunneling under your lawn, but finding one morning that they have created a huge, yawning pit."

The astronomers think that the hole must have been opened when the narrow jets of gas from some of the young stars in the region punctured the sheet of dust and gas that forms NGC 1999. The powerful radiation from a nearby adolescent star may also have helped to clear the hole. Whatever the precise chain of events, it could be an important glimpse into the way newborn stars rip apart their birth clouds.

Other members of the research team include Thomas Stanke of the European Southern Observatory, Germany; Amy Stutz of the Max-Planck Institute for Astronomy, Germany, and the Steward Observatory, Tucson; John Tobin of the University of Michigan, Ann Arbor; Lori Allen of the National Optical Astronomy Observatory, Tucson; Ali Babar of the NASA Herschel Science Center at the California Institute of Technology, Pasadena; and Will Fischer and Erin Kryukova, University of Toledo, Ohio.

Herschel is a European Space Agency cornerstone mission, with science instruments provided by consortia of European institutes and with important participation by NASA. NASA's Herschel Project Office is based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. JPL contributed mission-enabling technology for two of Herschel's three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the United States astronomical community. Caltech manages JPL for NASA.

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Rock and Roll: Titan's Gem Tumbler

It appears flash flooding has paved streambeds in the Xanadu region of Saturn's moon Titan with thousands of sparkling crystal balls of ice, according to scientists with NASA's Cassini spacecraft. By analyzing the way the terrain has scattered radar beams, scientists deduce the spheres measure at least a few centimeters (inches) and maybe up to a couple of meters (yards) in diameter. The spheres likely originated as part of water-ice bedrock in higher terrain in Xanadu.

"What we believe happened in this area is a lot like what creates polished river rocks on Earth," said Alice Le Gall, a postdoctoral fellow at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and the lead author of the study, which used the Cassini radar instrument. "Bouncing downstream smoothes out the edges of rocks."

As foothill residents know in southern California and other areas, sudden rains can trigger mudslides and flooding at the mountainous fringes of desert areas. Those flows can pick up boulders and debris and tumble them downstream. On Titan, the flows appear to have occurred periodically for eons, on a catastrophic scale. The process on Titan, however, involves rain made of liquid methane and ethane, rather than Earth's water rain. Titan's rocks are believed to be made primarily of water ice frozen into a hard mass about minus 180 degrees Celsius (minus 290 degrees Fahrenheit), rather than Earth's mineral rocks.

Earth-like river rocks have already been observed on Titan at the landing site of the European Space Agency's Huygens probe, near the equator in the borderland between the Adiri and Shangri-la regions. The landing site also showed signs of flash flooding that deposited cobblestones about 2 to 20 centimeters (1 to 8 inches) in diameter.

But the spidery channels in this southern lowland part of Xanadu looked brighter to Cassini's radar instrument than the Huygens landing area. In fact, the channels, which were scanned by Cassini in May 2008, are among the brightest features ever seen on Titan by the radar instrument.

In a paper now available online in the journal Icarus, Le Gall and colleagues concluded that the most plausible explanation for the extreme brightness of the Xanadu channels was a collection of transparent spherical sediments, packed more tightly together than the cobblestones at the Huygens landing site. The effect would be similar to bejeweling an area with light-catching rhinestones.

The spheres appear to be made of water ice – possibly doped with ammonia – that would look bright to the microwaves used by Cassini's radar. Spheres are good at sending light back in the direction it came from. This property has actually led manufacturers to use plastic spheres in reflective paints and tape, Le Gall said.

Xanadu may be an especially good gem grinder because of its broad expanse and gentle southward slope. Flows could have traveled long distances there and tumbled the chunks for hundreds of kilometers (miles). The subtle work to shape them into spheres could have come from fine grit rubbing against the rocks in the flowing methane. Or, ice may be malleable in Titan's cold temperatures, deforming plastically during the collisions rather than fracturing. The flows that transported these icy spheres probably traveled around 1 meter per second (2 mph).

"It's been really hard for a long time for people to understand why Xanadu is so bright," said Steve Wall, a radar team member at JPL. "You might not expect these kinds of geometries in a natural setting, but we believe this can explain the enigma."

The radar team plans to continue looking for other instances of small, smooth spheres in nature to increase their confidence about the explanation. They also said more study is needed on the mechanical properties of water ice at such cold temperatures.

"Here is yet another example of Titan as a world with Earth-like processes," said Linda Spilker, Cassini project scientist at JPL. "As the seasons change on Titan, maybe we'll get a chance to see methane flow through some of the river channels."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

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JPL Invites the Public to Annual Open House

NASA's Jet Propulsion Laboratory, Pasadena, Calif., invites the public to a close-up look at JPL's past, present and future at its annual Open House on Saturday, May 15, and Sunday, May 16, from 9 a.m. to 5 p.m. The event, themed "Worlds Beyond," features displays and demonstrations from numerous space missions, and a first look at JPL's recently renovated von Karman Visitor Center.

On special display will be the JPL-built Wide Field and Planetary Camera 2, retrieved from NASA's Hubble Space Telescope last year by space-walking astronauts. The instrument, affectionately known as the "Camera that Saved Hubble," is on loan from the Smithsonian Institution's National Air and Space Museum. The camera captured many of Hubble's iconic space images.

Other Open House highlights include: seeing JPL's next spacecraft bound for Mars, Mars Science Laboratory, under construction in the lab's largest "clean room;" life-size rover models in a "Mars" test bed; and JPL's Microdevices Lab, where engineers and scientists use tiny technology to revolutionize space exploration. Visitors can also see the sun through solar-safe telescopes, and learn how NASA instruments help scientists better understand global climate change.

JPL Open House provides a memorable experience for adult and kids, with plenty of hands-on activities, and opportunities to talk with scientists and engineers. Selected locations at Open House will be featured live online on Ustream TV at http://www.ustream.tv/channel/nasajpl on Sat., May 15, at 10 a.m., 11 a.m., noon and 1 p.m. Pacific time (1, 2, 3 and 4 p.m. Eastern time). Each time slot will feature a new location at the top of each hour.

JPL is located at 4800 Oak Grove Drive, Pasadena, Calif., 91109. Admission to Open House is free. Parking is also free, but is limited. To get to JPL, take the Berkshire Avenue/Oak Grove Drive exit from the 210 Freeway in La Canada/Flintridge. All visitors should wear comfortable shoes -- no buses will be provided from JPL parking lots. JPL will provide vans for mobility-challenged guests.

Vehicles entering NASA/JPL property are subject to inspection. Visitors cannot bring these items to NASA/JPL: weapons, explosives, incendiary devices, dangerous instruments, alcohol, illegal drugs, pets, all types of skates including skateboards, Segways and bicycles. No bags, backpacks or ice chests are allowed, except small purses and diaper bags.

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JPL Invites the Public to Annual Open House

NASA's Jet Propulsion Laboratory, Pasadena, Calif., invites the public to a close-up look at JPL's past, present and future at its annual Open House on Saturday, May 15, and Sunday, May 16, from 9 a.m. to 5 p.m. The event, themed "Worlds Beyond," features displays and demonstrations from numerous space missions, and a first look at JPL's recently renovated von Karman Visitor Center.

On special display will be the JPL-built Wide Field and Planetary Camera 2, retrieved from NASA's Hubble Space Telescope last year by space-walking astronauts. The instrument, affectionately known as the "Camera that Saved Hubble," is on loan from the Smithsonian Institution's National Air and Space Museum. The camera captured many of Hubble's iconic space images.

Other Open House highlights include: seeing JPL's next spacecraft bound for Mars, Mars Science Laboratory, under construction in the lab's largest "clean room;" life-size rover models in a "Mars" test bed; and JPL's Microdevices Lab, where engineers and scientists use tiny technology to revolutionize space exploration. Visitors can also see the sun through solar-safe telescopes, and learn how NASA instruments help scientists better understand global climate change.

JPL Open House provides a memorable experience for adult and kids, with plenty of hands-on activities, and opportunities to talk with scientists and engineers. Selected locations at Open House will be featured live online on Ustream TV at http://www.ustream.tv/channel/nasajpl on Sat., May 15, at 10 a.m., 11 a.m., noon and 1 p.m. Pacific time (1, 2, 3 and 4 p.m. Eastern time). Each time slot will feature a new location at the top of each hour.

JPL is located at 4800 Oak Grove Drive, Pasadena, Calif., 91109. Admission to Open House is free. Parking is also free, but is limited. To get to JPL, take the Berkshire Avenue/Oak Grove Drive exit from the 210 Freeway in La Canada/Flintridge. All visitors should wear comfortable shoes -- no buses will be provided from JPL parking lots. JPL will provide vans for mobility-challenged guests.

Vehicles entering NASA/JPL property are subject to inspection. Visitors cannot bring these items to NASA/JPL: weapons, explosives, incendiary devices, dangerous instruments, alcohol, illegal drugs, pets, all types of skates including skateboards, Segways and bicycles. No bags, backpacks or ice chests are allowed, except small purses and diaper bags.

You might like this article also : Misting cooling system, Patio misting system, CeMAP training, CeMAP courses.


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JPL Invites the Public to Annual Open House

NASA's Jet Propulsion Laboratory, Pasadena, Calif., invites the public to a close-up look at JPL's past, present and future at its annual Open House on Saturday, May 15, and Sunday, May 16, from 9 a.m. to 5 p.m. The event, themed "Worlds Beyond," features displays and demonstrations from numerous space missions, and a first look at JPL's recently renovated von Karman Visitor Center.

On special display will be the JPL-built Wide Field and Planetary Camera 2, retrieved from NASA's Hubble Space Telescope last year by space-walking astronauts. The instrument, affectionately known as the "Camera that Saved Hubble," is on loan from the Smithsonian Institution's National Air and Space Museum. The camera captured many of Hubble's iconic space images.

Other Open House highlights include: seeing JPL's next spacecraft bound for Mars, Mars Science Laboratory, under construction in the lab's largest "clean room;" life-size rover models in a "Mars" test bed; and JPL's Microdevices Lab, where engineers and scientists use tiny technology to revolutionize space exploration. Visitors can also see the sun through solar-safe telescopes, and learn how NASA instruments help scientists better understand global climate change.

JPL Open House provides a memorable experience for adult and kids, with plenty of hands-on activities, and opportunities to talk with scientists and engineers. Selected locations at Open House will be featured live online on Ustream TV at http://www.ustream.tv/channel/nasajpl on Sat., May 15, at 10 a.m., 11 a.m., noon and 1 p.m. Pacific time (1, 2, 3 and 4 p.m. Eastern time). Each time slot will feature a new location at the top of each hour.

JPL is located at 4800 Oak Grove Drive, Pasadena, Calif., 91109. Admission to Open House is free. Parking is also free, but is limited. To get to JPL, take the Berkshire Avenue/Oak Grove Drive exit from the 210 Freeway in La Canada/Flintridge. All visitors should wear comfortable shoes -- no buses will be provided from JPL parking lots. JPL will provide vans for mobility-challenged guests.

Vehicles entering NASA/JPL property are subject to inspection. Visitors cannot bring these items to NASA/JPL: weapons, explosives, incendiary devices, dangerous instruments, alcohol, illegal drugs, pets, all types of skates including skateboards, Segways and bicycles. No bags, backpacks or ice chests are allowed, except small purses and diaper bags.

You might like this article also : Misting cooling system, Patio misting system, CeMAP training, CeMAP courses.


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Engineers Diagnosing Voyager 2 Data System

Engineers have shifted NASA's Voyager 2 spacecraft into a mode that transmits only spacecraft health and status data while they diagnose an unexpected change in the pattern of returning data. Preliminary engineering data received on May 1 show the spacecraft is basically healthy, and that the source of the issue is the flight data system, which is responsible for formatting the data to send back to Earth. The change in the data return pattern has prevented mission managers from decoding science data.

The first changes in the return of data packets from Voyager 2, which is near the edge of our solar system, appeared on April 22. Mission team members have been working to troubleshoot and resume the regular flow of science data. Because of a planned roll maneuver and moratorium on sending commands, engineers got their first chance to send commands to the spacecraft on April 30. It takes nearly 13 hours for signals to reach the spacecraft and nearly 13 hours for signals to come down to NASA's Deep Space Network on Earth.

Voyager 2 launched on August 20, 1977, about two weeks before its twin spacecraft, Voyager 1. The two spacecraft are the most distant human-made objects, out at the edge of the heliosphere, the bubble the sun creates around the solar system. Mission managers expect Voyager 1 to leave our solar system and enter interstellar space in the next five years or so, with Voyager 2 on track to enter interstellar space shortly afterward. Voyager 1 is in good health and performing normally.

"Voyager 2's initial mission was a four-year journey to Saturn, but it is still returning data 33 years later," said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena. "It has already given us remarkable views of Uranus and Neptune, planets we had never seen close-up before. We will know soon what it will take for it to continue its epic journey of discovery."

The original goals for the two Voyager spacecraft were to explore Jupiter and Saturn.

As part of a mission extension, Voyager 2 also flew by Uranus in 1986 and Neptune in 1989, taking advantage of a once-in-176-year alignment to take a grand tour of the outer planets. Among its many findings, Voyager 2 discovered Neptune's Great Dark Spot and 450-meter-per-second (1,000-mph) winds. It also detected geysers erupting from the pinkish-hued nitrogen ice that forms the polar cap of Neptune's moon Triton. Working in concert with Voyager 1, it also helped discover actively erupting volcanoes on Jupiter's moon Io, and waves and kinks in Saturn's icy rings from the tugs of nearby moons.

Voyager 2 is about 13.8 billion kilometers, or 8.6 billion miles, from Earth. Voyager 1 is about 16.9 billion kilometers (10.5 billion miles) away from Earth.

The Voyagers were built by JPL, which continues to operate both spacecraft. Caltech manages JPL for NASA.

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NASA, JPL Websites Win Webby Awards

Three NASA sites have won awards in the 14th Annual Webby Awards -- the leading international honor for the world's best websites. NASA.gov was the People's Voice Winner for Government, and NASA's Jet Propulsion Laboratory was the People's Voice Winner in the science category for its Global Climate Change site. NASA Home & City Version 2.0 won the juried competition for Government.

A fourth NASA site, Kepler: The Search for Habitable Planets, was designated an official honoree in the science category. The Kepler site was created by teams at JPL and NASA Ames Research Center, Moffett Field, Calif.

Presented by The International Academy of Digital Arts and Sciences, The Webby Award recognizes excellence in technology and creativity. The Academy created the awards in 1996 to help drive the creative, technical, and professional progress of the Internet and evolving forms of interactive media. The winners were announced online May 4, 2010.

While members of The International Academy of Digital Arts and Sciences select the winners for the Webby Awards, the online community determines the winners of the People's Voice Awards.

Visit The 14th Annual Webby Awards for the complete list of winners and nominees.

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Radar Clicks Asteroid's Pic

Near-Earth asteroid 2005 YU55 was "imaged" by the Arecibo Radar Telescope in Puerto Rico on April 19. Data collected during Arecibo's observation of 2005 YU55 allowed the Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory to refine the space rock's orbit, allowing scientists to rule out any possibility of an Earth impact for the next 100 years.

The space rock was about 2.3 million kilometers (1.5 million miles) from Earth at the time this image of the radar echo was generated. The ghostly image has a resolution of 7.5 meters (25 feet) per pixel. It reveals 2005 YU55 as a spherical object about 400 meters (1,300 feet) in size.

Not only can the radar provide data on an asteroid's dimensions, but also on its exact location in space. Using Arecibo's high-precision radar astrometry capability, scientists were able to reduce orbit uncertainties for YU55 by 50 percent.

"At one time we had classified 2005 YU55 as a potential threat," said Steve Chesley, a scientist at JPL's Near-Earth Object Program Office. Prior to the Arecibo radar passes on April 19 thru 21, we had eliminated almost all upcoming Earth flybys as possibilities of impact. But there were a few that had a low remaining probability of impact. After incorporating the data from Arecibo, we were able to rule impacts out entirely for the next 100 years."

With more observations in the coming years, scientists may be able to accurately plot 2005 YU55's orbit even further out.

NASA detects, tracks and characterizes asteroids and comets passing close to Earth using both ground- and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them, and plots their orbits to determine if any could be potentially hazardous to our planet.

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.

More information about asteroids and near-Earth objects is at: http://www.jpl.nasa.gov/asteroidwatch.

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Cassini Returning Enceladus Gravity Data

NASA's Cassini spacecraft successfully completed its 26-hour gravity observation at Saturn's moon Enceladus this week, sending back data scientists will use to understand the moon's interior composition and structure.

The flyby took Cassini through the water-rich plume flaring out from Enceladus' south polar region, with a closest approach of about 100 kilometers (60 miles) occurring in the late afternoon of April 27, 2010, Pacific Time, or just after midnight April 28 UTC.

A steady radio link to NASA's Deep Space Network on Earth enabled Cassini's scientists to use the radio science instrument to measure the variations in the gravitational pull of Enceladus. Analyzing the wiggles will help scientists understand whether an ocean, pond or great lake lies under the famous "tiger stripe" fractures that spew water vapor and organic particles from the south polar region.

Results from the experiment will also tell scientists if bubbles of warmer ice in the interior rise toward that region's surface like an underground lava lamp.

Radio science was prime during the flyby and controlled spacecraft pointing. The optical instruments were not pointed at Enceladus during most of the flyby, so the imaging camera obtained some more distant pictures.

Cassini often relies on thrusters to control attitude during flybys such as this one, but this time it turned the thrusters off and relied on its reaction wheels. Using thrusters adds acceleration effects to the spacecraft, complicating the precise measurements needed for the radio science experiment.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL.

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