The docked space shuttle Discovery and the Canadian-built Dextre, also known as the Special Purpose Dextrous Manipulator, are featured in this photograph taken by the STS-133 crew aboard the station. The blackness of space and Earth's horizon provide the backdrop for the scene.

For more information visit http://www.nasa.gov/multimedia/imagegallery/image_feature_1877.html

NASA atmospheric scientists got an unexpected chance to study a curious phenomenon called "thundersnow" when a recent storm unleashed it right over their heads.

Walt Petersen and Kevin Knupp have traveled far and wide to study winter storms. They never dreamed that the most extraordinary one they'd see – featuring freakish thundersnow, a 50-mile long lightning bolt, and almost a dozen gravity waves -- would erupt in their own back yards. The storm hit Huntsville, Alabama, on the evening of January 9th.

"This incredible storm rolled right over the National Space Science and Technology Center where we work," says Knupp. "What luck!"

Snowstorms usually slip in silently, with soft snowflakes drifting noiselessly to Earth. Yet this Alabama snowstorm swept in with the fanfare of lightning and the growl of thunder.

Eyewitness Steve Coulter described the night's events: "It was as if a wizard was hurling lightning behind a huge white curtain. The flashes, muted inside thick, low hanging clouds, glowed purplish blue, like light through a prism. And then the thunder rumbled deep and low. This was one of the most beautiful things I've ever experienced.'"

It was a once-in-a-lifetime scene for anyone lucky enough to see it, but especially enthralling to scientists seeking the keys to nature's unique displays of power. Petersen and Knupp, with the help of graduate students from the University of Alabama-Huntsville, had their research equipment primed and ready.

From his at-home workstation, Petersen can monitor lightning detector networks and control radars, which he used to measure and record the storm. But when the storm first hit his response was a little less scientific: "I was so excited that I ran outside in my house slippers to take pictures," he recalls. At around 10:30 p.m., he heard the first rumble of thundersnow. "My first thought was, 'excellent, a bonus!'"

What made this snowstorm act like a thunderstorm? Petersen explains:

"You rarely have lightning in a snowstorm. But in this case, some unique conditions set the stage for it. Moist air at the bottom of the storm was lifted up, rapidly forming snow and ice. Some of the snow even grew in pellet forms called 'graupel,'" he says.

Snowflakes and ice pellets of different sizes ascended at different rates--and they began to exchange charges. The process isn't fully understood, but it could be a result of particles rubbing together (like wool socks on carpet). As the cloud charged up, it began to act less like an ordinary winter snowstorm and more like a summer thunderstorm.

It's no coincidence that the thundersnow was accompanied by massive roller coasters of air known as gravity waves. These waves are similar to waves in the ocean, but roll through the air instead of water.

"There was a nearly constant, uniform progression of gravity waves, starting at Monte Sano, a small mountain a few miles east of us, and moving westward, right over our building," says Knupp, who spent most of the storm's duration with his eyes riveted on instrument displays inside the team's mobile X-band radar van. "An easterly flow of air on the other side of the mountain ridge bumped into and was pushed over Monte Sano, forming 11 separate waves, about one per hour."

He believes the clockwork up and down motion of the waves created variations in the updrafts responsible for the heavy snow, leading to the charge separation that generated lightning. Unfortunately, he was knee-deep in computer displays instead of snow when the storm's most impressive lightning bolt set the sky aglow.

"This bolt reached from the tower on Monte Sano Mountain all the way to Molton, Alabama, about 50 miles away," says Knupp. "And I missed it."

Was he disappointed?

"I felt cheated, but it was worth the trade off. I learned some interesting things."

Spoken like a true scientist.

For more information visit http://science.nasa.gov/science-news/science-at-nasa/2011/24feb_thundersnow/

Imagine flying around in space to examine a future space observatory that’s under construction today. Thanks to animators and web developers, Internet users can get a fly-by tour of NASA's next-generation, tennis court-sized James Webb Space Telescope on their computer.

This new interactive utilizes cutting-edge Flash and 3-D interactivity through an engine for Flash called Away 3D. Models of this complexity are rarely truly interactive, and this one comes at the start of a trend that will bring true 3D interactivity to the web via Flash.

"We wanted to make the 3-D Webb feature fun and inviting," said Michael McClare, Senior Media Producer for the Webb telescope project for Honeywell at NASA's Goddard Space Flight Center in Greenbelt, Md. He said that users do not need to download anything to make the interactive fly-by tour work.

The interactive fly-by tour was created to allow people to get familiar with the Hubble Space Telescope’s successor. For years NASA and contractors have been brainstorming, designing, building, and testing various components of the telescope—infrared cameras, a massive multi-layer sunshield, 18 mirror segments—that will allow the Webb to peer deeper than ever into the cosmos.

The interactive Fly-by tour can be found on-line at www.nasa.gov/externalflash/webb3d

Users have complete control of the spacecraft. This differs from other 3-D interactives that use movies to mimic 3-D control—here you have true 360 degree interaction.

This interactive Fly-by tour allows smooth movements of the Webb telescope—users can make the spacecraft spin gently with just a nudge. The interactive actually allows for views of the telescope from any angle. Popup description boxes add a discovery/learning element to the feature, and in the large black box behind the Primary Mirror, users will be able to peer inside the telescope to see the actual location of instruments within the Integrated Science Instrument Module (ISIM) Structure.

After a brief opening sequence offering images of the space telescope intercut with Webb's science objective simulations, the Webb telescope appears in 3-D and a menu appears under the heading. Users can manipulate the telescope at will or can use the menu for a more guided tour of Webb's major components with choices to view Optics, Instruments or (Support) Systems.

Selecting "Optics" will tour viewers around the mirrors and the backplane. The "Instruments" menu choice guides the viewer through the Mid-Infrared Instrument (MIRI), Near-Infrared Camera (NIRCam), Near-Infrared Spectrograph (NIRSpec), Fine Guidance Sensor Tunable Filter Imager (FGS-TFI) and Integrated Science Instrument Module (ISIM). Finally, the "Systems" view includes the Sunshield, pallet structure, spacecraft bus, solar panels, high gain antenna, star trackers and momentum trim tab.

The James Webb Space Telescope is NASA's next-generation space observatory and successor to the Hubble Space Telescope. The most powerful space telescope ever built, Webb will observe the most distant objects in the universe, provide images of the very first galaxies ever formed, provide insight to how solar systems evolve and help explore planets around distant stars. The Webb telescope is a joint project of NASA, the European Space Agency, and the Canadian Space Agency.

The interactivity was the creation of a team of advanced web designers, programmers and visualizers. The team includes: Kris Meister, Director of Alien Communication, Washington, D.C.; Tyler Chase, Animator, University of Maryland Baltimore County, Baltimore Md.; Katie Lewis, web designer, NASA Goddard/University of Maryland Baltimore County, Md.; and Mike McClare.

So next time you want to explore something huge and amazing, seeing it as if it were right in front of you, go on-line and take the fly-by tour around the James Webb Space Telescope.

For more information visit http://www.nasa.gov/topics/universe/features/webb-interactive.html

This astronaut photograph illustrates the diverse agricultural landscape in the western part of Minas Gerais state in Brazil. Though most widely known for its mineral wealth, Minas Gerais is also a large agricultural producer for Brazil.

The fields in this image are located southwest of the city of Perdizes, which means “partridges” in Portuguese. A mix of regularly-gridded polygonal fields and circular center-pivot fields marks the human use of the region. Small streams (and their adjacent floodplains) of the Araguari River extend like fingers throughout the landscape.

The visual diversity of the field forms is matched by the variety of crops: sunflowers, wheat, potatoes, coffee, rice, soybeans, and corn are among the products of the region. While the Northern Hemisphere is still in the grip of winter, crops are growing in the Southern Hemisphere, as indicated by the many green fields. Fallow fields—not in active agricultural use—display the violet, reddish, and light tan soils common to this part of Brazil. Darker soils are often rich in iron and aluminum oxides, and are typical of highly weathered soil that forms in hot, humid climates.

For more information visit http://earthobservatory.nasa.gov/IOTD/view.php?id=49352&src=imgrss

On Feb. 11, 2011, a group of 57 avid space enthusiasts received a rare “behind-the-scenes” glimpse at NASA’s Ames Research Center and then instantly shared their adventure with the world.

These space geeks are also known as “tweeps”—people who use Twitter, follow space-themed accounts, such as @NASA_Ames, and tweet about their love for space.

More than 400 people registered online for a chance to participate in the Tweetup, which included tours of the Vertical Motion Simulator, Future Flight Central, Fluid Mechanics Lab and the Kepler Science Operations Center.

The sky was blue and spirits were high that morning as tweeps started trickling in to the NASA Ames Exploration Center. As Heather Archuletta (@Pillownaut) tweeted, “@NASA_Ames #exo tweeps waiting not-very-patiently for #nasatweetup to begin, LOL! Let's go early! =).”

The theme of the inaugural Tweetup focused on “planet hunting” to coincide with the midpoint anniversary of the Kepler mission. The tweeps started off the day listening to Kepler Deputy Science Team Lead Natalie Batalha, SOFIA Project Scientist Pamela Marcum and David Morrison, Director of the Carl Sagan Center for the Study of Life in the Universe.

Beth Johnson (@ladypembroke) tweeted, “I must admit that I get excited and a little verklempt when thinking about @NASAKepler. I'm such an astrogeek!”

While listening to Morrison speak, Dom Narducci from Prescott, Ariz. (@dnathe4th) tweeted, “#nasatweetup #exo debunks every 2012 myth in about four minutes. Science Win.”

Morrison shared his enthusiasm for reaching out to cyberspace. “Twitter reaches a lot of people,” he said. “If those people are interested in NASA, Twitter is a great way to talk to them, assuming you can do so in 20 words or roughly 140 characters.”

Don Breedwell (@MrDDon), a special education teacher, traveled from Nashville, Tenn. to tweet back to his students about his experience. “NASA was on my bucket list,” said Breedwell. “I'm tweeting all the things we're trying to do for the future.”

As the day progressed, word spread through the Twitterverse about the Tweetup and at one point, the event ranked fourth in the most-tweeted topics in the San Francisco Bay Area.

The Tweetup concluded with a group photo and a visit to the gift shop back at the Exploration Center. Robyn Villavecchia, (@fizzviic) a former Apollo propulsion chemist, tweeted, “After a day at the NASATweetup @NASA_Ames, it is so hard to come back to Earth.”

For more information visit http://www.nasa.gov/centers/ames/news/features/2011/tweetup.html

What would our solar system look like if visitors from other worlds took a series of pictures?

NASA's MESSENGER spacecraft did just that by piecing together the first portrait of our solar system from the inside looking out. Comprised of 34 images, the mosaic provides a complement to the solar system portrait--from the outside looking in--taken by Voyager 1 in 1990.

"Obtaining this portrait was a terrific feat by the MESSENGER team," says MESSENGER principal investigator Sean Solomon, of the Carnegie Institution of Washington. "This snapshot of our neighborhood also reminds us that Earth is a member of a planetary family that was formed by common processes four and a half billion years ago. Our spacecraft is soon to orbit the innermost member of the family, one that holds many new answers to how Earth-like planets are assembled and evolve."

MESSENGER's Wide Angle Camera (WAC) captured the images on Nov. 3 and 16, 2010. In the mosaic, all of the planets are visible except for Uranus and Neptune, which--at distances of 3.0 and 4.4 billion kilometers--were too faint to detect. Earth's moon and Jupiter's Galilean satellites (Callisto, Ganymede, Europa and Io) can be seen in the WAC image insets. The solar system's perch on a spiral arm of the Milky Way galaxy also afforded a beautiful view of a portion of the galaxy in the bottom center.

"The curved shape of the mosaic is due to the inclination of MESSENGER's orbit from the ecliptic, the plane in which Earth and most planets orbit, which means that the cameras must point up to see some planets and down to see others," explains imaging team member Brett Denevi of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md. "The images are stretched to make it easier to detect the planets, though this stretch also highlights light scattered off of the planet limbs, and in some cases creates artifacts such as the non-spherical shape of some planets."

Assembling this portrait was no easy feat, says Solomon. "It's not easy to find a moment when many of the planets are within a single field of view from that perspective, and we have strong Sun-pointing constraints on our ability to image in some directions."

APL's Hong Kang, from MESSENGER’s guidance and control team, used the Jet Propulsion Laboratory's Solar System Simulator to pinpoint the relative positions of MESSENGER and the planets to determine if it was possible to see the planets from MESSENGER at any given time.

"I used the celestial coordinates of the planets at the time I wanted to observe them to verify with simulations that MESSSENGER could see each of the planets," Kang explains. "I also used a satellite tool kit to verify that we had the planets in the field of view of MESSENGER’s Mercury Dual Imaging System."

The MESSENGER team then had to determine how long the exposures needed to be for each planet.

"From exposure times that worked for previous imaging of stars with visual magnitudes similar to those of the planets, we chose exposure times that would allow us to obtain the appropriate number of counts (i.e., amount of light) in each planet image," explains APL's Nori Laslo, the mission's Operations Lead and Instrument Sequencer for MDIS.

"We decided to take images using both the Narrow Angle Camera and the Wide Angle Camera for each planet so that we would cover the sky surrounding the planets and also image the planets themselves at as high a resolution as possible," she adds. "I took all of these parameters, along with a variety of related settings, and began building the command sequence with the library of MDIS commands that we have to configure and control the camera system."

Robin Vaughan, who worked with Kang to coordinate the pointing and timing of the MDIS, also played a role in Voyager's portrait.

"I was working as an optical navigation analyst at JPL for the Voyager Neptune encounter," says Vaughan, the lead engineer for MESSENGER's guidance and control (attitude control) subsystem at APL. "I had to plan and generate the pointing commands for pictures of Neptune and its satellites against background stars that we used to improve our estimate of the spacecraft's trajectory leading up to the Neptune encounter. Voyager's solar system portrait was done a few years after that flyby and was coordinated by the imaging team. Our optical navigation image planning software was used to double check the pointing commands they had designed and confirm what they expected to see in each image."

Vaughan did the same thing for MESSENGER’s portrait, using Kang’s designs. "I used the SPICE trajectory files for the spacecraft generated by MESSENGER's navigation team, as well as routines in the SPICE toolkit, to write a software program that would identify windows when each of the planets would be visible to MDIS given the constraints on pivot angle and Sun keep-in zone for spacecraft attitude," she says.

From a technical standpoint, the MESSENGER portrait was a little more complicated than what was done for Voyager because we had to stay within the Sun keep-in constraints. "With Voyager so far out in the solar system, the Sun is much fainter and there were no constraints on the overall spacecraft attitude as far as the Sun was concerned," Vaughan says. "Being in the inner solar system, MESSENGER has to constantly keep the sunshade pointing toward the sun, which limits the periods when the different planets can be viewed even with the extra degree of freedom that MDIS has with its pivot capability."

Denevi says the experiment was humbling. "Seeing our solar system as just these little specks of light, it reminds you of how lucky we are that we've had the chance, through so many missions, to get up close and explore the incredible diversity and geology that each planet and moon displays," she says. "Mercury has been just a dot on the horizon for most of history, and we get to fill in the details and know it as a real world. What an amazing opportunity!"

For more information visit http://www.nasa.gov/topics/solarsystem/features/family_portrait.html

Mission controllers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., watched as data downlinked from the Stardust spacecraft indicated it completed its closest approach with comet Tempel 1. An hour after closest approach, the spacecraft turned to point its large, high-gain antenna at Earth. It is expected that images of the comet's nucleus collected during the flyby will be received on Earth starting at about midnight California time (3 a.m. EST on Tuesday, Feb. 15).

Preliminary data already transmitted from the spacecraft indicate the time of closest approach was about 8:39 p.m. PST (11:39 p.m. EST), at a distance of 181 kilometers (112 miles) from Tempel 1.

This is a bonus mission for the comet chaser, which previously flew past comet Wild 2 and returned samples from its coma to Earth. During this bonus encounter, the plan called for the spacecraft to take images of the comet's surface to observe what changes occurred since a NASA spacecraft last visited. (NASA's Deep Impact spacecraft executed an encounter with Tempel 1 in July 2005).

Stardust-NExT is a low-cost mission that will expand the investigation of comet Tempel 1 initiated by NASA's Deep Impact spacecraft. JPL, a division of the California Institute of Technology in Pasadena, manages Stardust-NExT for NASA's Science Mission Directorate, Washington, D.C. Lockheed Martin Space Systems, Denver, built the spacecraft and manages day-to-day mission operations.

For more information visit http://www.nasa.gov/mission_pages/stardust/news/stardust20110214c.html

They're called atmospheric rivers - narrow regions in Earth's atmosphere that transport enormous amounts of water vapor across the Pacific or other regions. Aptly nicknamed "rivers in the sky," they can transport enough water vapor in one day, on average, to flood an area the size of Maryland 0.3 meters (1 foot) deep, or about seven times the average daily flow of water from the Mississippi River into the Gulf of Mexico. The phenomenon was the subject of a recent major emergency preparedness scenario led by the U.S. Geological Survey, "ARkStorm," which focused on the possibility of a series of strong atmospheric rivers striking California - a scenario of flooding, wind and mudslides the USGS said could cause damages exceeding those of Hurricane Katrina in 2005.

While atmospheric rivers are responsible for great quantities of rain that can produce flooding, they also contribute to beneficial increases in snowpack. A series of atmospheric rivers fueled the strong winter storms that battered the U.S. West Coast from western Washington to Southern California from Dec. 10 to 22, 2010, producing 28 to 64 centimeters (11 to 25 inches) of rain in certain areas. The atmospheric rivers also contributed to the snowpack in the Sierras, which received 75 percent of its annual snow by Dec. 22, the first full day of winter.

To improve our understanding of how atmospheric rivers form and behave and evaluate the operational use of unmanned aircraft for investigating these phenomena, NASA scientists, aircraft and sensors will participate in a National Oceanic and Atmospheric Administration-led airborne field campaign slated to begin Feb. 11.

Called Winter Storms and Pacific Atmospheric Rivers, or WISPAR, the field campaign, which continues through the end of February, is designed to demonstrate new technology, contribute to our understanding of atmospheric rivers and assist NOAA in potentially conducting offshore monitoring of atmospheric rivers to aid in future weather predictions.

A NASA Global Hawk unmanned aircraft operated out of NASA's Dryden Flight Research Center in Southern California is scheduled to depart Dryden Friday morning, Feb. 11, on the campaign's first science flight. The 24-hour flight will study an atmospheric river currently developing in the Pacific Ocean off Hawaii that appears as though it will impact the Oregon-California coast this weekend. Aboard the Global Hawk will be new weather reconnaissance devices called dropsondes developed by the National Center for Atmospheric Research that will take temperature, wind and other readings as they descend through an atmospheric river. Also aboard will be an advanced water vapor sensor - the High-Altitude Monolithic Microwave Integrated Circuit Sounding Radiometer, or HAMSR - created by NASA's Jet Propulsion Laboratory in Pasadena, Calif.

The remote-sensing HAMSR instrument analyzes the heat radiation emitted by oxygen and water molecules in the atmosphere to determine their density and temperature. The instrument operates at microwave frequencies that can penetrate clouds, enabling it to determine temperature, humidity and cloud structure under all weather conditions. This capability is critical for studying atmospheric processes associated with bad weather, like the conditions present during atmospheric river events.

HAMSR Principal Investigator Bjorn Lambrigtsen of JPL says the instrument - the most accurate and sensitive of its kind in the world - will help scientists better understand these unique weather phenomena.

"The WISPAR campaign is intended to study the concentrated streams of tropical moisture that sometimes get connected with cold fronts and winter storms approaching the U.S. West Coast - sometimes called the pineapple express, since they often originate near Hawaii - which can result in very intense rain events," Lambrigtsen said. "HAMSR, flying on NASA's unpiloted Global Hawk well above the weather but close enough to get a much more detailed picture than is possible from a satellite, will be used to map out this phenomenon and answer scientific questions about the formation and structure of these systems."

NASA's Global Hawk is an ideal platform from which to conduct WISPAR science because it is able to fly long distances, stay aloft for more than 24 hours and travel at high and low altitudes that could be dangerous for humans. Lambrigtsen will be at Dryden in the Global Hawk Operations Center during the flights, using data from the sensor and other information to adjust the Global Hawk's flight track, as necessary, to optimize the sampling of the atmospheric rivers.

Lambrigtsen said the public can monitor the progress of the WISPAR science flights in real time on a WISPAR version of JPL's hurricane portal website at http://winterscience.jpl.nasa.gov/WISPAR2011/ . The site will display the most recent satellite images, the Global Hawk flight track and a real-time subset of HAMSR data.

For more information visit http://www.jpl.nasa.gov/news/news.cfm?release=2011-048

A bonus round is something one usually associates with the likes of a TV game show, not a pioneering deep space mission. "We are definitely in the bonus round," said Stardust-NExT Project Manager Tim Larson of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "This spacecraft has already flown by an asteroid and a comet, returned comet dust samples to Earth, and now has almost doubled its originally planned mission life. Now it is poised to perform one more comet flyby."


A Successful Prime Mission

NASA's Stardust spacecraft was launched on Feb. 7, 1999, on a mission that would explore a comet as no previous mission had. Before Stardust, seven spacecraft from NASA, Russia, Japan and the European Space Agency had visited comets – they had flight profiles that allowed them to perform brief encounters, collecting data and sometimes images of the nuclei during the flyby.

Like those comet hunters before it, Stardust was tasked to pass closely by a comet, collecting data and snapping images. It also had the ability to come home again, carrying with it an out-of -this-world gift for cometary scientists – particles of the comet itself. Along the way, the telephone booth-sized comet hunter racked up numerous milestones and more than a few "space firsts."

In the first round of its prime mission, Stardust performed observations of asteroid Annefrank, only the sixth asteroid in history to be imaged close up. After that, Stardust racked up more points of space exploration firsts. It became the first spacecraft to capture particles of interstellar dust for Earth return. It was first to fly past a comet and collect data and particles of comet dust (hurtling past it at almost four miles per second) for later analysis. Then, it was first to make the trip back to Earth after traveling beyond the orbit of Mars (a two-year trip of 1.2 billion kilometers, or 752 million miles). When Stardust dropped off its sample return capsule from comet Wild 2, the capsule became the fastest human-made object to enter Earth's atmosphere. The mission was also the first to provide a capsule containing cometary dust specimens, speciments that will have scientists uncovering secrets of comets for years to come.

With such a high tally of "firsts" on its scoreboard, you'd think Stardust could receive a few parting gifts and leave the game. And an important part of the original spacecraft is currently enjoying retirement – albeit a high-profile one: Stardust's 100-pound sample return capsule is on display in the main hall (Milestones of Flight) of the Smithsonian's National Air and Space Museum in Washington. But the rest of NASA's most-seasoned comet hunter is still up there – and there is work still to be done.

"We placed Stardust in a parking orbit that would carry it back by Earth in a couple of years, and then asked the science community for proposals on what could be done with a spacecraft that had a lot of zeros on its odometer, but also had some fuel and good miles left in it," said Jim Green, director of NASA's Planetary Science Division.


Moving into the Bonus Round

In January 2007, from a stack of proposals with intriguing ideas, NASA chose Stardust-NExT (Stardust's Next Exploration of Tempel). It was a plan to revisit comet Tempel 1 at a tenth of the cost of a new, from-the-ground-up mission. Comet Tempel 1 was of particular interest to NASA. It had been the target of a previous NASA spacecraft visit in July 2005. That mission, Deep Impact, placed a copper-infused, 800-pound impactor on a collision course with the comet and observed the results from the cosmic fender-bender via the telescopic cameras onboard the larger part of Deep Impact, a "flyby" spacecraft observing from a safe distance.

"The plan for our encounter is to be more hospitable to comet Tempel 1 than our predecessor," said Joe Veverka, principal investigator of Stardust-NExT from Cornell University in Ithaca, N.Y. "We will come within about 200 kilometers [124 miles] of Tempel 1 and view the changes that took place over the past five-and-a-half years."

That period of time is significant for Tempel 1 -- it is the period of time it takes the comet to orbit the sun once. Not much happens during a comet's transit through the chilly reaches of the outer solar system. But when it nears perihelion (the point in its orbit that an object, such as a planet or a comet, is closest to the sun), things begin to sizzle.

"Comets can be very spectacular when they come close to the sun, but we still don't understand them as well as we should," said Veverka. "They are also messengers from the past. They tell us how the solar system was formed long ago, and Stardust-NExT will help us understand how much they have changed since their formation."

So the spacecraft that had traveled farther afield than any of its predecessors was being sent out again in the name of scientific opportunity. In between spacecraft and comet lay four-and-a-half years, over a billion kilometers (646 million miles), and more than a few hurdles along the way.

Your Mileage May Vary

"One of the challenges with reusing a spacecraft designed for a different prime mission is you don't get to start out with a full tank of gas," said Larson. "Just about every deep-space exploration spacecraft has a fuel supply customized to get the job done, with some held in reserve for contingency maneuvers and other uncertainties. Fortunately, the Stardust mission navigation team did a great job, the spacecraft operated extremely well, and there was an adequate amount of contingency fuel aboard after its prime mission to make this new comet flyby possible – but just barely."

Just how much fuel is in Stardust's tanks for its final act?

"We estimate we have a little under three percent of the fuel the mission launched with," said Larson. "It is an estimate, because no one has invented an entirely reliable fuel gauge for spacecraft. There are some excellent techniques with which we have made these estimates, but they are still estimates."

One of the ways mission planners can approximate fuel usage is to look at the history of the vehicle's flight and how many times and for how long its rocket motors have fired. When that was done for Stardust, the team found their spacecraft's attitude and translational thrusters had fired almost half-a-million times each over the past 12 years.

"There is always a little plus and minus with each burn. When you add them all up, that is how you get the range of possible answers on how much fuel was used," said Larson.

Fuel is not the only question that needs to be addressed on the way to a second comet encounter. Added into the mix is the fact a comet near the sun can fire off jets of gas and dust that can cause a change in its orbit, sometimes in unexpected ways, potentially causing a precisely designed cometary approach to become less precise. Then there are the distances involved. Stardust will fly past comet Tempel 1 on almost the opposite side of the sun from Earth, making deep-space communication truly, well, deep space. Add into the mix the Stardust spacecraft itself. Launched when Bill Clinton was in the White House, Stardust has been cooked and frozen countless times during its trips from the inner to outer solar system. It has also weathered its fair share of radiation-packed solar storms. But while its fuel tank may be running near-empty, that doesn't mean Stardust doesn't have anything left in the tank.

"All this mission's challenges are just that – challenges," said Larson. "We believe our team and our spacecraft are up to meeting every one of them, and we're looking forward to seeing what Tempel 1 looks like these days."


The Final Payoff

Larson, Veverka and the world will get their chance beginning a few hours after the encounter on Monday, Feb. 14, at about 8:56 p.m. PST (11:56 p.m. EST), when the first of 72 bonus-round images of the nucleus of comet Tempel 1 are downlinked.

All images of the comet will be taken by the spacecraft's navigation camera – an amalgam of spare flight-ready hardware left over from previous NASA missions: Voyager (launched in 1977), Galileo (launched in 1989), and Cassini (launched in 1997). Each image will take about 15 minutes to transmit. The first five images to be received and processed on the ground are expected to include a close up of Tempel 1's nucleus. All data from the flyby (including the images and science data obtained by the spacecraft's two onboard dust experiments) are expected to take about 10 hours to reach the ground.

Stardust-NExT is a low-cost mission that will expand the investigation of comet Tempel 1 initiated by NASA's Deep Impact spacecraft. JPL, a division of the California Institute of Technology in Pasadena, manages Stardust-NExT for the NASA Science Mission Directorate, Washington, D.C. Joe Veverka of Cornell University, Ithaca, N.Y., is the mission's principal investigator. Lockheed Martin Space Systems, Denver Colo., built the spacecraft and manages day-to-day mission operations.

For more information visit http://www.nasa.gov/mission_pages/stardust/news/stardust20110209.html

NASA will host several live activities for the Stardust-NExT mission's close encounter with comet Tempel 1. The closest approach is expected at approximately 8:37 p.m. PST (11:37 p.m. EST) on Feb. 14, with confirmation received on Earth at about 8:56 p.m. PST (11:56 p.m. EST).

Live coverage of the Tempel 1 encounter will begin at 8:30 p.m. PST on Feb. 14 on NASA Television and the agency's website. The coverage will include live commentary from mission control at NASA's Jet Propulsion Laboratory in Pasadena, Calif., and video from Lockheed Martin Space System's mission support area in Denver.

Live coverage of a news briefing is planned for 10 a.m. PST on Feb. 15. Scheduled participants are:
-- Ed Weiler, NASA associate administrator, Science Mission Directorate, Washington
-- Joe Veverka, Stardust-NExT principal investigator, Cornell University, Ithaca, N.Y.
-- Tim Larson, Stardust-NExT project manager, JPL
-- Don Brownlee, Stardust-NExT co-investigator, University of Washington, Seattle

Mission coverage schedule (all times PST and subject to change):

-- 8:30 to 10 p.m., Feb. 14: Live NASA TV commentary begins from mission control; includes coverage of closest approach and the re-establishment of contact with the spacecraft following the encounter.

-- Midnight to 1:30 a.m., Feb. 15: NASA TV commentary will chronicle the arrival and processing of the first five of 72 close-approach images the team expects to be downlinked after the encounter. The images are expected to include a close-up view of the comet's surface.

-- 10 a.m., Feb. 15: News briefing

-- Starting on Feb. 9, NASA TV will air Stardust-NExT mission animation and other video during its Video File segments. For NASA TV streaming video, scheduling and downlink information, visit: http://www.nasa.gov/ntv .

-- Commentary and the news conference will also be carried live on one of JPL's Ustream channels. During events, viewers can engage in a real-time chat and submit questions to the Stardust-NExT team at: http://www.ustream.tv/user/NASAJPL2 .

The public can watch a real-time animation of the Stardust-NExT comet flyby using NASA's new "Eyes on the Solar System" Web tool. JPL created this 3-D environment, which allows people to explore the solar system from their computers. It is available at: http://solarsystem.nasa.gov/eyes .

This flyby of Tempel 1 will give scientists an opportunity to look for changes on the comet's surface since it was visited by NASA's Deep Impact spacecraft in July 2005. Since then, Tempel 1 has completed one orbit of the sun, and scientists are looking forward to monitoring any differences in the comet.

During its 12 years in space, Stardust became the first spacecraft to collect samples of a comet (Wild 2 in 2004), which were delivered to Earth in 2006 for study. The Stardust-NExT mission is managed by JPL for NASA's Science Mission Directorate in Washington. Lockheed Martin Space Systems in Denver built the spacecraft and manages day-to-day mission operations.

For More information visit http://www.jpl.nasa.gov/news/news.cfm?release=2011-044b

A city that rarely sees snowfall, Huntsville, Ala., was blanketed the evening of Jan. 9 under several inches of snow following a winter storm that also produced a rare "thundersnow" or lightning flashes. This unique weather event allowed scientists at NASA's Marshall Space Flight Center and the University of Alabama in Huntsville the opportunity to assemble one of the most detailed snowfall datasets on record for the deep southern tier of the continental United States.

Scientists in Huntsville were eager to measure the snowstorm's effects since the city hadn't seen a storm of this magnitude since March of 1993 when the city received a record 7.3 inches of snowfall. As the flakes started to fall, researchers worked to deploy several advanced radars, a large collection of snow particle measurement instrumentation and a 3-D lightning location array to gather storm data.

Advanced instruments known as "dual-polarimetric" radars from UAHuntsville scanned the snow-producing clouds Sunday night and Monday morning, measuring precipitation contents, and wind-flow while ground-based camera and laser imaging systems measured individual snowflake sizes, the rate of fall of the snowflakes, and the amount of melted water associated with the snowfall.

Dr. Walt Petersen's "Disdrometer and Radar Observations of Precipitation" group, or DROP Facility, of the Marshall Center and NASA's Global Precipitation Measurement (GPM) mission provided a large cluster of precipitation measurement equipment currently managed at Marshall and guided the Advanced Radar for Meteorological and Operational Research (ARMOR) polarimetric radar operations as part of the study with UAHuntsville scientists.

"NASA's GPM mission has invested significant resources in equipment that can help us better determine what an orbiting, satellite-based remote sensor sees at the top of Earth's atmosphere when it is snowing or raining at the surface of the Earth," said Petersen. "The snowflakes and raindrops produced in clouds between the Earth's surface and the top of the atmosphere cause changes in the microwave radiation measured at the top of the atmosphere. These changes occur as a function of the cloud thickness, as well as precipitation type and shape, and are particularly sensitive to the presence of snowflakes or raindrops."

The snowstorm provided an excellent opportunity for Petersen's team to take detailed measurements of precipitation and use those observations as a type of database or model to simulate what the constellation of GPM satellites would see from space. By combining the observations at the ground with those of the polarimetric radar, Petersen's team expects to learn a great deal about the processes responsible for creating the snowfall, and more accurately measure the water content of the snow from space and the rate at which that snow-water equivalent accumulates on the ground.

"The snow rate accumulation is important for winter weather preparedness on Earth," said Petersen. "Several of the Southern states were criticized for their lack of planning. It would mean a great deal if we could predict the intensity of the storm to allow cities more opportunity to be ready for this type of once in a decade weather event."

Petersen and his team worked in tandem with researchers and scientists from the Department of Atmospheric Science led by Professor Kevin Knupp at UAHuntsville. Knupp's team deployed the UAHuntsville mobile X-band radar (MAX) and used it to scan over the top of the NASA GPM instruments at the National Space Science and Technology Center in Huntsville. By combining the radar measurements from at least two of the radars, Knupp's team hopes to relate the wind flow within the storm to the precipitation measurements taken by Petersen. Knupp noted that "the atmosphere was full of gravity waves," features in the atmosphere that produce rapid up and downward motions and enhance the rate at which snow falls.

"Our team feels lucky and even surprised to have been able to marshal our collective resources to sample such a unique event in this part of the United States," said Petersen. "A team of scientists, including Dr. Lawrence Carey, Patrick Gatlin and Matt Wingo of UAHuntsville, just finished making similar measurements in Finland, yet here we are doing something similar in Huntsville, of all places."

The combined research team was able to collect the most detailed observations of thundersnow -- including the actual propagation path of individual lighting flashes -- ever collected in the Southeastern United States. These observations will help the NASA and UAHuntsville teams determine how electrical processes in thunderstorms function by comparing the observations to those collected in more frequently observed summer thunderstorms.

The ARMOR radar and Northern Alabama lightning-mapping array projects represent collaborative efforts between the Marshall Center and team members and partners from the University of Alabama in Huntsville. These efforts are funded in part by the NOAA/NASA GOES-R satellite program, NASA’s Tropical Rainfall Measuring Mission and Global Precipitation Measurement Missions, all managed by NASA’s Goddard Space Flight Center in Greenbelt, Md., and NASA's Earth Science Division in Washington.

For more information visit http://www.nasa.gov/topics/nasalife/features/thundersnow.html

Piece by piece a team of NASA researchers put together a huge composite and metal structure that looked a lot like high-tech tinkertoys on steroids.

The structural mechanics and concepts branch engineers are going back to the past to try to explore the future. Most of them were involved with large space structure research done at NASA's Langley Research Center from the 70s to the early 90s. Now they're dusting off some of the hardware to see if the concepts would work in the 21st century.

"Back almost 20 years ago we were doing research in how to build large space telescopes that astronauts could put together on orbit during a space walk," said senior researcher John Dorsey. "Since NASA is now looking at in-space operations to support Near Earth Object missions as well as satellite servicing, we are going back here at Langley and starting to look at telescope assembly again. But now because we are working in the human robotics systems project we are going to try to do it with robots."

Dorsey and five others recently spent about three and a half hours in a corner of the Langley aircraft hangar -- the only place big enough to construct the almost 46-foot wide (14 meter) node and strut superstructure indoors. The truss system, which has been in storage for years, was developed as part of a four-year program called the Precision Segmented Reflector that ended in 1992. The program goal, which was successfully accomplished, was to come up with a structural configuration that was lightweight, low-cost, compactly stored and easy to put together. Reflectors could then be attached to the truss structure to form a space telescope mirror.

"What we're doing now is inventorying the parts and all the mechanical components and making sure they work okay," added Dorsey. "The easiest way to do that was to put the giant structure together."

Immediately after the team put the three-dimensional puzzle of the 315 struts and 84 nodes together -- they took it apart and packed it into six crates. Langley is shipping the crates to a new robotics center at West Virginia University that was built with support of a grant from NASA's Goddard Space Flight Center.

"We've been collaborating with Goddard, which has a lot of experience in Hubble repair missions," said researcher Dorsey. "Now they're doing work in robotic satellite servicing and already have experience with robotic operations on orbit. Goddard has a continuing grant with the facility at West Virginia University."

Langley and Goddard researchers will consult and work with the WVU robotics center team to help develop the machines and procedures needed to assemble the massive rod and joint telescope mirror platform.

For More information visit http://www.nasa.gov/topics/technology/features/truss.html

NASA Deputy Administrator Lori Garver returned Feb. 1 from a four-day trip to Israel where she represented NASA at an international space conference, met with students and paid tribute to the memory of Israeli astronaut Ilan Ramon.

Garver’s visit was highlighted by her participation in the Sixth Annual Ilan Ramon International Space Conference, a two-day forum for Israel’s space community to discuss technologies, programs and strategies with representatives from around the world. The conference included meetings with European Space Agency Director General Jean-Jacques Dordain, Israeli Minister of Science and Technology Daniel Hershkowitz, Menachem Greenblum, director general of Israel’s Ministry of Science and Technology, and Israel Space Agency Director General Zvi Kaplan.

Garver delivered a keynote address Jan. 30 that highlighted the importance of international cooperation.

“We’re now entering our second decade with a continuous human presence in space,” Garver said. “This was the future that Ilan Ramon contributed to. It is a future that we strive to create every day at NASA. It is our great privilege and honor to do that work with Israel and the rest of the international community.”

Ramon was Israel’s first and only astronaut. He and six crewmates aboard space shuttle Columbia died on Feb. 1, 2003, when their ship broke apart en route to a planned landing in Florida. Garver commemorated the eighth anniversary of the tragedy with a Jan. 31 visit to Ramon’s gravesite at a cemetery near Nahalal, Israel. There, she placed wreaths on the graves of Ramon and his son, Asaf, an Israeli air force pilot who died in a 2009 training accident.

Garver also took time during her trip to meet with Israeli students. On Jan. 30, she participated in a space and science workshop at Tel Aviv University, addressing a packed assembly and answering questions from the audience. The following day, on Jan. 31, Garver visited the Ort Brotherhood Gilboa’a Comprehensive School in Naura, Israel, where she met with more than 30 students. Some of the students took the top prize in Israel’s FIRST robotics competition in 2010 and participated in the international finals in Atlanta.

News media representatives seeking additional information on the trip should contact Michael Cabbage in NASA’s Office of Communication at mcabbage@nasa.gov or 202-358-1600.

For more information visit http://www.nasa.gov/about/highlights/garver_israel.html

If you're distributing 412 million data products in a year to more than 1.1 million users, how do you ever make sure people are getting what they want? The Earth Observing System Data and Information System (EOSDIS) Project based at Goddard Space Flight Center, Greenbelt, Md., came up with a simple formula: They ask.

EOSDIS is the network of Earth science data centers that process, store, and make available the trove of data from NASA's past and current Earth-observing satellites. For the past seven years, EOSDIS management has collected thousands of responses from users of its system as a way to both gather metrics and improve on its delivery. EOSDIS works with the American Customer Satisfaction Index (ACSI) to systematically track its standing and progress through the eyes of its users.

In the recently released ACSI ratings for 2010, EOSDIS achieved a customer satisfaction score well above the standard for government agencies and even higher scores in several key categories. EOSDIS scored a 77 on a scale of 0 to 100, while the government benchmark is 65. EOSDIS has maintained scores in the high 70s over the past several years.

"This accomplishment is particularly noteworthy given its consistency, even though customer expectations rose during that period," said Ron Oberbillig, Chief Operating Officer of the Federal Consulting Group, executive agent within the federal government that works with ACSI on behalf of all agencies. Oberbillig particularly lauded EOSDIS for scores in the upper eighties when customers were asked about their likelihood to use the data centers in the future and willingness to recommend the data centers to colleagues.

"We use the ACSI surveys as a way to measure our performance, but also as a way to keep improving on what we do" said Jeanne Behnke, EOSDIS Deputy Project Manager for Operations at NASA Goddard.

Behind the Scenes

Satellites have ushered in a new era of Earth science in the past few decades. A constantly orbiting fleet of NASA satellites keeps its sensors trained on our blue planet – capturing the intricacies of its atmosphere, the seasonal cycles of plant growth and sea ice, and the patterns in ocean circulation and temperature.

EOSDIS manages constant streams of data for scientists to dissect and discover new knowledge about how our planet's dynamic systems work and interact with one another. But before any scientific investigation can begin, the raw data itself must be received, stored, processed and made available. It's a process that often occurs behind the scenes but ultimately enables all the NASA-related studies of Earth and its climate. EOSDIS manages this flow of information – from satellites in space to data processing facilities to a scientist's desktop – with a network of 12 Earth science data centers in the U.S. These Earth science data centers are located at NASA centers or partner institutions and specialize in specific types of datasets, such as snow and ice, atmospheric or ocean data.

NASA's Earth Observing System (EOS) was devised to make long-term, comprehensive measurements of Earth's interrelated systems – to capture their fundamental nature and any natural or man-made changes. In the 1990s, EOS identified 24 key measurements of Earth systems, and EOSDIS manages the gathering and distribution of those measurements from end to end – from command and control of several satellites, to coordination of data gathering through ground stations the world over, to the distribution interface on NASA websites where scientists can download data.

The wide-ranging effort essentially takes a long-term measure of the scope of Earth's land, atmosphere and ocean systems. While EOS is only about 15 years old, these data records will become more valuable as they capture a longer period of time and more natural and man-made variability in the various Earth systems. That makes the EOSDIS task of not only processing but also archiving all NASA data a vital component to the future of Earth science.

Moving Forward

“Likewise, the annual use of the ACSI survey will become more valuable to EOSDIS over time, as the organization can see how users respond to changes prompted by their comments,” EOSDIS outreach manager Carol Boquist said. The ACSI score is certain to remain a key metric for an organization whose goal is to make as much data available in as easy a manner as possible.

"At our core, we are delivering an extensive array of products to a national and international base of scientists, researchers, educators, and the general public," Boquist said. "With new data products always coming online and our users' needs constantly changing, the only way to make sure we're succeeding is to ask."

NASA's Earth Observing System has a website that has sections specifically written for scientists, educators, kids, or media and press.

For more information http://www.nasa.gov/topics/earth/features/eosdis-feedback.html

NASA's NEOWISE mission has completed its survey of small bodies, asteroids and comets, in our solar system. The mission's discoveries of previously unknown objects include 20 comets, more than 33,000 asteroids in the main belt between Mars and Jupiter, and 134 near-Earth objects (NEOs). The NEOs are asteroids and comets with orbits that come within 45 million kilometers (28 million miles) of Earth's path around the sun.

NEOWISE is an enhancement of the Wide-field Infrared Survey Explorer, or WISE, mission that launched in December 2009. WISE scanned the entire celestial sky in infrared light about 1.5 times. It captured more than 2.7 million images of objects in space, ranging from faraway galaxies to asteroids and comets close to Earth.

In early October 2010, after completing its prime science mission, the spacecraft ran out of the frozen coolant that keeps its instrumentation cold. However, two of its four infrared cameras remained operational. These two channels were still useful for asteroid hunting, so NASA extended the NEOWISE portion of the WISE mission by four months, with the primary purpose of hunting for more asteroids and comets, and to finish one complete scan of the main asteroid belt.

"Even just one year of observations from the NEOWISE project has significantly increased our catalog of data on NEOs and the other small bodies of the solar systems," said Lindley Johnson, NASA's program executive for the NEO Observation Program.

Now that NEOWISE has successfully completed a full sweep of the main asteroid belt, the WISE spacecraft will go into hibernation mode and remain in polar orbit around Earth, where it could be called back into service in the future.

In addition to discovering new asteroids and comets, NEOWISE also confirmed the presence of objects in the main belt that had already been detected. In just one year, it observed about 153,000 rocky bodies out of approximately 500,000 known objects. Those include the 33,000 that NEOWISE discovered.

NEOWISE also observed known objects closer and farther to us than the main belt, including roughly 2,000 asteroids that orbit along with Jupiter, hundreds of NEOs and more than 100 comets.

These observations will be key to determining the objects' sizes and compositions. Visible-light data alone reveal how much sunlight reflects off an asteroid, whereas infrared data is much more directly related to the object's size. By combining visible and infrared measurements, astronomers also can learn about the compositions of the rocky bodies -- for example, whether they are solid or crumbly. The findings will lead to a much-improved picture of the various asteroid populations.

NEOWISE took longer to survey the whole asteroid belt than WISE took to scan the entire sky because most of the asteroids are moving in the same direction around the sun as the spacecraft moves while it orbits Earth. The spacecraft field of view had to catch up to, and lap, the movement of the asteroids in order to see them all.

"You can think of Earth and the asteroids as racehorses moving along in a track," said Amy Mainzer, the principal investigator of NEOWISE at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We're moving along together around the sun, but the main belt asteroids are like horses on the outer part of the track. They take longer to orbit than us, so we eventually lap them."

NEOWISE data on the asteroid and comet orbits are catalogued at the NASA-funded International Astronomical Union's Minor Planet Center, a clearinghouse for information about all solar system bodies at the Smithsonian Astrophysical Observatory in Cambridge, Mass. The science team is analyzing the infrared observations now and will publish new findings in the coming months.

When combined with WISE observations, NEOWISE data will aid in the discovery of the closest dim stars, called brown dwarfs. These observations have the potential to reveal a brown dwarf even closer to us than our closest known star, Proxima Centauri, if such an object does exist. Likewise, if there is a hidden gas-giant planet in the outer reaches of our solar system, data from WISE and NEOWISE could detect it.

The first batch of observations from the WISE mission will be available to the public and astronomical community in April.

"WISE has unearthed a mother lode of amazing sources, and we're having a great time figuring out their nature," said Edward (Ned) Wright, the principal investigator of WISE at UCLA.

JPL manages WISE for NASA's Science Mission Directorate at the agency's headquarters in Washington. The mission was competitively selected under NASA's Explorers Program, which NASA's Goddard Space Flight Center in Greenbelt, Md., manages. The Space Dynamics Laboratory in Logan, Utah, built the science instrument, and 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. JPL manages NEOWISE for NASA's Planetary Sciences Division. The mission's data processing also takes place at the Infrared Processing and Analysis Center.

For more information visit http://www.nasa.gov/mission_pages/WISE/news/wise20110201.html