Friday, April 29, 2011

The Legacy of Endeavour

Space shuttle Endeavour has spent 19 years pushing boundaries, and its final mission will allow that legacy to live on.

Among Endeavour’s missions was the first to include four spacewalks, and then the first to include five. Its STS-67 mission set a length record almost two full days longer than any shuttle mission before it. Its airlock is the only one to have seen three spacewalkers exit through it for a single spacewalk. And in its cargo bay, the first two pieces of the International Space Station were joined together.

On STS-134, however, it will help push boundaries of a different sort as it delivers a new, cutting edge science experiment to the space station: the Alpha Magnetic Spectrometer.

“The AMS is an amazing story all by itself,” said Gary Horlacher, lead space shuttle flight director for the mission. “They’ve been working on this for well over 15 years now. It’s bigger than a VW bug, and it will be able to look at things that the other observatories aren’t even looking at. It is, without a doubt, going to continue to rewrite our future as we try to figure out our past.”

The Alpha Magnetic Spectrometer is a state-of-the-art, high energy particle physics experiment built in Geneva by a collaboration of 16 different countries. It will search for clues on what the universe is made of and how it began, the origin of dark matter, antimatter and strangelets, pulsars, blazers and gamma ray bursters. And that’s just what the scientists know to look for.

“I am quite confident that once we start measuring data in space, we will find things that we never anticipated,” NASA’s AMS Project Manager Trent Martin said. “And those things will lead to potential new areas of study, new areas of science and maybe even redefine some of the physics books.”

It’s a new area of investigation for International Space Station science, and the only experiment of its type in the universe; although there are detectors on the ground trying to answer the same questions, they’re limited to the particles that make it through the Earth’s atmosphere, or that they create themselves. Meanwhile several telescopes are already in space, but they can only measure light, not particles.

Thanks to the extension of the International Space Station program, the AMS will be sifting through the cosmos for years after Endeavour has retired. And some of the other aspects of Endeavour’s mission will help ensure that the station is able to continue providing a home for it and the many other science experiments going on in space.

After AMS is installed on station’s truss during the fourth day of the mission, a pallet of spare parts will be added to the space station on the mission’s flight day 5. Then there will be a string of spacewalks – the last spacewalks to be performed by a shuttle crew – dedicated to getting the station in the best possible shape for the end of the space shuttle program.

The spacewalkers will top off a leaky ammonia loop and lubricate one of the massive joints that turn the station’s solar array wings. They’ll also add to the Russian segment of the station a handhold for the station’s robotic arm, extending the arm’s range to that area, and make a permanent home on the station’s truss for the shuttle robotic arm’s 50-foot long boom extension, so that it can be left behind to give the station’s arm a greater reach.

None of the tasks are urgent – the ammonia leak is very small and wouldn’t really need to be dealt with for another two years or so, for instance, and the joint would eventually need the lubrication but doesn’t yet. However, getting these things done is easier when there’s a shuttle present – it costs the station less oxygen, and the extra hands on deck improve efficiency. So, it’s better to get them done now.

“These spacewalks are kind of a catch all – an accumulation of the stuff we haven’t been able to get to on the last several flights,” Derek Hassmann, lead station flight director for the mission, said. “But it’s all about getting the station in the best posture to give it the most margin and most capability for a long life after we stop flying shuttles.”

But for all that one of the primary focuses of the mission is preparing the station for the shuttle’s final wheel stop, everyone agrees that the subject of the end isn’t one that they’ve spent much time contemplating. Horlacher and Hassmann say they’ve worked hard to ensure that they disconnect from the commotion associated with STS-134 being Endeavour’s final flight, and focus on making it every bit as successful as Endeavour’s first. And the mission’s commander, Mark Kelly, agreed.

“It is what it is,” he said. “I’ll think about it more after the mission. We’re just going to try to do the job and do it safely.”

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Thursday, April 28, 2011

Voyager Set to Enter Interstellar Space

More than 30 years after they left Earth, NASA's twin Voyager probes are now at the edge of the solar system. Not only that, they're still working. And with each passing day they are beaming back a message that, to scientists, is both unsettling and thrilling.

The message is, "Expect the unexpected."

"It's uncanny," says Ed Stone of Caltech, Voyager Project Scientist since 1972. "Voyager 1 and 2 have a knack for making discoveries."

Today, April 28, 2011, NASA held a press conference to reflect on what the Voyager mission has accomplished--and to preview what lies ahead as the probes prepare to enter the realm of the Milky Way itself.

The adventure began in the late 1970s when the probes took advantage of a rare alignment of outer planets for an unprecedented Grand Tour. Voyager 1 visited Jupiter and Saturn, while Voyager 2 flew past Jupiter, Saturn, Uranus and Neptune. (Voyager 2 is still the only probe to visit Uranus and Neptune.)

When pressed to name the top discoveries from those encounters, Stone pauses, not for lack of material, but rather an embarrassment of riches. "It's so hard to choose," he says.

Stone's partial list includes the discovery of volcanoes on Jupiter's moon Io; evidence for an ocean beneath the icy surface of Europa; hints of methane rain on Saturn's moon Titan; the crazily-tipped magnetic poles of Uranus and Neptune; icy geysers on Neptune's moon Triton; planetary winds that blow faster and faster with increasing distance from the sun.

"Each of these discoveries changed the way we thought of other worlds," he says Stone.

In 1980, Voyager 1 used the gravity of Saturn to fling itself slingshot-style out of the plane of the Solar System. In 1989, Voyager 2 got a similar assist from Neptune. Both probes set sail into the void.

Sailing into the void sounds like a quiet time, but the discoveries have continued.

Stone sets the stage by directing our attention to the kitchen sink. "Turn on the faucet," he instructs. "Where the water hits the sink, that's the sun, and the thin sheet of water flowing radially away from that point is the solar wind. Note how the sun 'blows a bubble' around itself."

There really is such a bubble, researchers call it the "heliosphere," and it is gargantuan. Made of solar plasma and magnetic fields, the heliosphere is about three times wider than the orbit of Pluto. Every planet, asteroid, spacecraft, and life form belonging to our solar system lies inside.

The Voyagers are trying to get out, but they're not there yet. To locate them, Stone peers back into the sink: "As the water (or solar wind) expands, it gets thinner and thinner, and it can't push as hard. Abruptly, a sluggish, turbulent ring forms. That outer ring is the heliosheath--and that is where the Voyagers are now."

The heliosheath is a very strange place, filled with a magnetic froth no spacecraft has ever encountered before, echoing with low-frequency radio bursts heard only in the outer reaches of the solar system, so far from home that the sun is a mere pinprick of light.

"In many ways, the heliosheath is not like our models predicted,” says Stone.

In June 2010 Voyager 1 beamed back a startling number: zero. That's the outward velocity of the solar wind where the probe is now. No one thinks the solar wind has completely stopped; it may have just turned a corner. But which way? Voyager 1 is trying to figure that out through a series of "weather vane" maneuvers, in which V1 turns itself in a different direction to track the local breeze. The old spacecraft still has some moves left, it seems.

No one knows exactly how many more miles the Voyagers must travel before they "pop free" into interstellar space. Most researchers believe, however, that the end is near. "The heliosheath is 3 to 4 billion miles in thickness," estimates Stone. "That means we'll be out within five years or so."

There is plenty of power for the rest of the journey. Both Voyagers are energized by the radioactive decay of a Plutonium 238 heat source. This should keep critical subsystems running through at least 2020.

After that, he says, "Voyager will become our silent ambassador to the stars."

Each probe is famously equipped with a Golden Record, literally, a gold-coated copper phonograph record. It contains 118 photographs of Earth; 90 minutes of the world's greatest music; an audio essay entitled Sounds of Earth (featuring everything from burbling mud pots to barking dogs to a roaring Saturn 5 liftoff); greetings in 55 human languages and one whale language; the brain waves of a young woman in love; and salutations from the Secretary General of the United Nations. A team led by Carl Sagan assembled the record as a message to possible extraterrestrial civilizations that might encounter the spacecraft.

"A billion years from now, when everything on Earth we've ever made has crumbled into dust, when the continents have changed beyond recognition and our species is unimaginably altered or extinct, the Voyager record will speak for us," wrote Carl Sagan and Ann Druyan in an introduction to a CD version of the record.

Some people note that the chance of aliens finding the Golden Record is fantastically remote. The Voyager probes won't come within a few light years of another star for some 40,000 years. What are the odds of making contact under such circumstances?

On the other hand, what are the odds of a race of primates evolving to sentience, developing spaceflight, and sending the sound of barking dogs into the cosmos?

Expect the unexpected, indeed.

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Wednesday, April 27, 2011

Robonaut Hand, Ship Bearing Head to Space

Robonaut 2 went into space on shuttle Discovery’s STS-133 to show that humanoid robots can work there. A Robonaut hand and arm unit is going up on the following shuttle flight, Endeavour's STS-134 mission to commemorate the work done on Earth for the project.

The robotic appendage is one of dozens of commemorative items the crew of Endeavour's mission are taking with them to mark their own achievements and that of NASA's youngest shuttle on its final flight.

After Endeavour returns from its two-week stay aboard the International Space Station, the commemorative items will be displayed in museums and collections around the world.

The Mary Rose Museum in Portsmouth, England, loaned a 3-inch wooden ball from the 16th century ship "Mary Rose" so it could sail in the vast ocean of space. The "Mary Rose" was one of the first purpose-built warships and was raised in 1982 after more than 400 years underwater. The ball, called a "parrel," was part of the mechanism used to raise sails up the masts.

The "Mary Rose" has one more connection to NASA: astronaut Michael Foale worked as a volunteer diver on the ship's excavation in 1981. The astronaut would later fly the space shuttle, to the Russian space station Mir and to the International Space Station.

Another museum-sponsored piece will go into orbit, the 5-star insignia worn by General Henry "Hap" Arnold, an architect of the modern Air Force. The insignia belongs to the National Museum of the U.S. Air Force in Dayton, Ohio, which holds numerous items from Arnold in its collection.

A number of the items on Endeavour's Official Flight Kit manifest, such as pins, flags and patches, will be given as awards after returning to Earth.

Some of the items will be awarded to Boy Scouts who earn the new robotics merit badge. There are 100 of the merit badges going along with Endeavour.

The astronauts are allowed to pick personal items to take into orbit, too. Sometimes they choose mementos of their accomplishments or things associated with their hometowns or other locations.

A small gold bar from the U.S. Merchant Marine Academy will make the trip inside Endeavour. STS-134 Commander Mark Kelly graduated from the academy in 1986.

A poem from the Tucson Poetry Center in Arizona also is making the trip, along with an Archie Comics comic book cover.

Objects ranging from a metal disk from the National Institute of Nuclear Physics in Rome to a pennant from Tuscany are representing Italy on STS-134, the home nation of European Space Agency Mission Specialist Roberto Vittori.

The objects continue a tradition of taking items into space that began with NASA's first astronauts. During the 50 years of astronauts launching into space, commemorative objects have flown to the moon's surface and made repeated orbits of Earth, returning later to inspire those who could not make the trip themselves and remind astronauts of their accomplishments.

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Tuesday, April 26, 2011

NASA Technology Looks Inside Japan's Nuclear Reactor

Design techniques honed at NASA's Jet Propulsion Laboratory in Pasadena, Calif., for Mars rovers were used to create the rover currently examining the inside of Japan's nuclear reactors, in areas not yet deemed safe for human crews.

The iRobot PackBot employs technologies used previously in the design of "Rocky-7," which served as a terrestrial test bed at JPL for the current twin Mars rovers, Spirit and Opportunity. PackBot's structural features are modeled after Rocky-7, including the lightweight, high-torque actuators that control the rover; and its strong, lightweight frame structure and sheet-metal chassis.

PackBot's other "ancestor," called Urbie, was an urban reconnaissance robot with military and disaster response applications. Urbie's lightweight structure and rugged features also made it useful in emergency response situations; for example, at sites contaminated with radiation and chemical spills, and at buildings damaged by earthquakes. Urbie's physical structure was designed by iRobot Corp., Bedford, Mass., while JPL was responsible for the intelligent robot's onboard sensors and vision algorithms, which helped the robot factor in obstacles and determine an appropriate driving path. Following the success of Urbie's milestones, the team at iRobot created its successor: PackBot.

Since 2002, iRobot has delivered variations of the PackBot model to the U.S. Army, U.S. Air Force and U.S. Navy. The tactical robot's first military deployment was to Afghanistan in July 2002, to assist soldiers by providing "eyes and ears" in the most dangerous or inaccessible areas. It was also used to search through debris at Ground Zero after the Sept. 11, 2001 attacks in New York.

Recently, iRobot provided two PackBots to help after the devastating March 11, 2011, earthquake and tsunami in Japan. The PackBot models, currently taking radioactivity readings in the damaged Fukushima Daiichi nuclear power plant buildings, are equipped with multiple cameras and hazard material sensors. The images and readings provided by the PackBots indicated radiation levels are still too high to allow human repair crews to safely enter the buildings.

Urbie was a joint effort of the Defense Advanced Research Project's Agency's (DARPA) Tactical Mobile Robot program, JPL, iRobot Corp., the Robotics Institute of Carnegie Mellon University, and the University of Southern California's Robotics Research Laboratory. JPL is managed for NASA by the California Institute of Technology in Pasadena.

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Sunday, April 24, 2011

JPL Tweetup Previews Missions: Mars, Jupiter and More

NASA's Jet Propulsion Laboratory in Pasadena, Calif., will host a Tweetup for approximately 120 Twitter followers on Monday, June 6.

With four space missions launching this year and an asteroid belt encounter nearly underway, 2011 will be one of the busiest ever in planetary exploration. Tweetup participants will interact with JPL scientists and engineers about these upcoming missions: Aquarius, to study ocean salinity; Grail, to study the moon's gravity field; Juno to Jupiter; and the Mars Science Laboratory/Curiosity rover. Participants also will learn about the Dawn mission and its upcoming encounter with the asteroid Vesta.

The Tweetup will include a tour of JPL, robotics demonstrations and a last chance to see the Curiosity rover before it ships to Florida to prepare for a November launch. Tour stops will include the Spacecraft Assembly Facility, where Curiosity is under construction, the mission control center of NASA's Deep Space Network, and JPL's new Earth Science Visitor Center.

Tweetup participants also will mingle with fellow attendees and the staff behind the tweets on @NASA, @NASAJPL, @MarsRovers, @AsteroidWatch and more.

Registration for the event opens at noon PDT (3 p.m. EDT) on Tuesday, April 26, and it closes at noon PDT (3 p.m. EDT) on Wednesday, April 27. For more information about the Tweetup and to sign up, visit: .

NASA Television will broadcast portions of the Tweetup on June 6 at: and .

Find all the ways to connect and collaborate with NASA at:
For more information about JPL, visit: . JPL is managed for NASA by the California Institute of Technology in Pasadena.

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Thursday, April 21, 2011

Ultraviolet Spotlight on Plump Stars in Tiny Galaxies

Astronomers using NASA's Galaxy Evolution Explorer may be closer to knowing why some of the most massive stellar explosions ever observed occur in the tiniest of galaxies.

"It's like finding a sumo wrestler in a little 'Smart Car,'" said Don Neill, a member of NASA's Galaxy Evolution Explorer team at the California Institute of Technology in Pasadena, and lead author of a new study published in the Astrophysical Journal.

"The most powerful explosions of massive stars are happening in extremely low-mass galaxies. New data are revealing that the stars that start out massive in these little galaxies stay massive until they explode, while in larger galaxies they are whittled away as they age, and are less massive when they explode," said Neill.

Over the past few years, astronomers using data from the Palomar Transient Factory, a sky survey based at the ground-based Palomar Observatory near San Diego, have discovered a surprising number of exceptionally bright stellar explosions in so-called dwarf galaxies up to 1,000 times smaller than our Milky Way galaxy. Stellar explosions, called supernovae, occur when massive stars -- some up to 100 times the mass of our sun -- end their lives.

The Palomar observations may explain a mystery first pointed out by Neil deGrasse Tyson and John Scalo when they were at the University of Austin Texas (Tyson is now the director of the Hayden Planetarium in New York, N.Y.). They noted that supernovae were occurring where there seemed to be no galaxies at all, and they even proposed that dwarf galaxies were the culprits, as the Palomar data now indicate.

Now, astronomers are using ultraviolet data from the Galaxy Evolution Explorer to further examine the dwarf galaxies. Newly formed stars tend to radiate copious amounts of ultraviolet light, so the Galaxy Evolution Explorer, which has scanned much of the sky in ultraviolet light, is the ideal tool for measuring the rate of star birth in galaxies.

The results show that the little galaxies are low in mass, as suspected, and have low rates of star formation. In other words, the petite galaxies are not producing that many huge stars.

"Even in these little galaxies where the explosions are happening, the big guys are rare," said co-author Michael Rich of UCLA, who is a member of the mission team.

In addition, the new study helps explain why massive stars in little galaxies undergo even more powerful explosions than stars of a similar heft in larger galaxies like our Milky Way. The reason is that low-mass galaxies tend to have fewer heavy atoms, such as carbon and oxygen, than their larger counterparts. These small galaxies are younger, and thus their stars have had less time to enrich the environment with heavy atoms.

According to Neill and his collaborators, the lack of heavy atoms in the atmosphere around a massive star causes it to shed less material as it ages. In essence, the massive stars in little galaxies are fatter in their old age than the massive stars in larger galaxies. And the fatter the star, the bigger the blast that will occur when it finally goes supernova. This, according to the astronomers, may explain why super supernovae are occurring in the not-so-super galaxies.

"These stars are like heavyweight champions, breaking all the records," said Neill.

Added Rich, "These dwarf galaxies are especially interesting to astronomers, because they are quite similar to the kinds of galaxies that may have been present in our young universe, shortly after the Big Bang. The Galaxy Evolution Explorer has given us a powerful tool for learning what galaxies were like when the universe was just a child."

Caltech leads the Galaxy Evolution Explorer mission and is responsible for science operations and data analysis. NASA's Jet Propulsion Laboratory in Pasadena manages the mission and built the science instrument. Caltech manages JPL for NASA. The mission was developed under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. Researchers sponsored by Yonsei University in South Korea and the Centre National d'Etudes Spatiales (CNES) in France collaborated on this mission.

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Wednesday, April 20, 2011

Cassini Sees Saturn Electric Link With Enceladus

NASA is releasing the first images and sounds of an electrical connection between Saturn and one of its moons, Enceladus. The data collected by the agency's Cassini spacecraft enable scientists to improve their understanding of the complex web of interaction between the planet and its numerous moons. The results of the data analysis are published in the journals Nature and Geophysical Research Letters.

Scientists previously theorized an electrical circuit should exist at Saturn. After analyzing data that Cassini collected in 2008, scientists saw a glowing patch of ultraviolet light emissions near Saturn's north pole that marked the presence of a circuit, even though the moon is 240,000 kilometers (150,000 miles) away from the planet.

The patch occurs at the end of a magnetic field line connecting Saturn and its moon Enceladus. The area, known as an auroral footprint, is the spot where energetic electrons dive into the planet's atmosphere, following magnetic field lines that arc between the planet's north and south polar regions.

"The footprint discovery at Saturn is one of the most important fields and particle revelations from Cassini and ultimately may help us understand Saturn's strange magnetic field," said Marcia Burton, a Cassini fields and particles scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It gives us the first visual connection between Saturn and one of its moons."

The auroral footprint measures approximately 1,200 kilometers (750 miles) by less than 400 kilometers (250 miles), covering an area comparable to California or Sweden. At its brightest, the footprint shone with an ultraviolet light intensity far less than Saturn's polar auroral rings, but comparable to the faintest aurora visible at Earth without a telescope in the visible light spectrum. Scientists have not found a matching footprint at the southern end of the magnetic field line. Jupiter's active moon Io creates glowing footprints near Jupiter's north and south poles, so scientists suspected there was an analogous electrical connection between Saturn and Enceladus. It is the only known active moon in the Saturn system with jets spraying water vapor and organic particles into space. For years, scientists used space telescopes to search Saturn's poles for footprints, but they found none.

"Cassini fields and particles instruments found particle beams aligned with Saturn's magnetic field near Enceladus, and scientists started asking if we could see an expected ultraviolet spot at the end of the magnetic field line on Saturn," said Wayne Pryor, a lead author of the Nature study released today, and Cassini co-investigator at Central Arizona College in Coolidge, Ariz. "We were delighted to find the glow close to the 'bulls-eye' at the center of our target."

In 2008, Cassini detected a beam of energetic protons near Enceladus aligned with the magnetic field and field-aligned electron beams. A team of scientists analyzed the data and concluded the electron beams had sufficient energy flux to generate a detectable level of auroral emission at Saturn. A few weeks later, Cassini captured images of an auroral footprint in Saturn's northern hemisphere. In 2009, a group of Cassini scientists led by Donald Gurnett at the University of Iowa in Iowa City, detected more complementary signals near Enceladus consistent with currents that travel from the moon to the top of Saturn's atmosphere, including a hiss-like sound from the magnetic connection. That paper was published in March in Geophysical Research Letters.

The water cloud above the Enceladus jets produces a massive, ionized "plasma" cloud through its interactions with the magnetic bubble around Saturn. This cloud disturbs the magnetic field lines. The footprint appears to flicker in these new data, so the rate at which Enceladus is spewing particles may vary.

"The new data are adding fuel to the fire of some long-standing debates about this active little moon," said Abigail Rymer, the other lead author of the Nature study and a Cassini team scientist based at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "Scientists have been wondering whether the venting rate is variable, and these new data suggest that it is."

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

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Monday, April 18, 2011

GOES-13 Satellite Animation Shows U.S. Severe Storms and Tornado Outbreak

The GOES-13 satellite captured images of the powerful weather system that triggered severe weather in the southern U.S. this weekend, and NASA created an animation to show its progression. GOES-13 satellite data showed the strong cold front as it moved eastward from Saturday through Monday and generated tornadoes before moving off-shore into the Atlantic Ocean. NASA's Aqua satellite also captured data from the system and took the temperature of the cold front's cloud tops and revealing severely cold temperatures of some of the thunderstorms.

The Geostationary Operational Environmental Satellite called GOES-13 monitors weather in the eastern half of the U.S. and is operated by NOAA. The NASA GOES Project at NASA's Goddard Space Flight Center in Greenbelt, Md. creates images and animations from the GOES satellite data. The NASA GOES Project created an animation of the satellite imagery from April 15 through April 17 that showed the movement of the powerful cold front through the eastern U.S. In the movie, you can see the low pressure area over Oklahoma on April 15, in a tight circular rotation and watch it move east bringing the cold front with it.

NOAA's Storm Prediction Center noted that the system generated 243 tornadoes in 13 states in three days, from April 14-16. According to the Weather Channel, the weather system generated 29 tornadoes on April 14 across the states of Oklahoma, Kansas, Arkansas and Texas. As the storm moved east, 73 tornadoes touched down in Alabama, Mississippi, Illinois, Arkansas, Kentucky, Missouri and Louisiana on April 15. On Saturday, April 16, 51 tornadoes were reported in North Carolina, Virginia, South Carolina, Alabama, Georgia and Maryland. Alabama, Mississippi, North Carolina and Virginia have all declared a state of emergency.

The National Weather Service ranks the power of a tornado by the Enhanced-F scale or "EF" Scale. The EF Scale is a set of wind estimates (not measurements) based on damage. Its uses three-second gusts estimated at the point of damage based on a judgment of 8 levels of damage to the 28 indicators. These estimates vary with height and exposure. To see the indicators and scale, visit: ›

The National Weather Service in Oklahoma reported that at least 21 tornadoes touched down in that state. The two strongest tornadoes were of EF3 and EF2 strength. The EF3 had wind speeds between 136 to 165 miles per hour and touched down in the town of Tushka, Atoka County. The EF2 had winds between 111 to 135 mph, and touched down near Lake Eucha in Delaware County. Weaker tornadoes were reported in 12 other counties in Oklahoma.

As the system continued to move east, an EF1 tornado touched down in Little Rock, Ark. early Friday morning, April 15, with winds between 86 and 110 mph. The National Weather Service also confirmed EF1 tornadoes in western Ark., near the town of Dyer, Crawford County and Branch, in Franklin County.

In Kentucky, the two tornadoes that touched down were both in Trigg County. The National Weather Service confirms that one was an EF1 tornado with sustained winds of 90 mph that touched down just southwest of Cadiz, Ky. The other was an EF) in the same vicinity that touched down briefly.

When the front swept through North Carolina on Saturday, April 16, the National Weather Service confirmed six tornadoes hit the central part of the state. The motion of the line of clouds associated with the front and the severe weather can be seen on the GOES-13 satellite animation. Reports of tornadoes came from Alamance, Cumberland, Lee, Person and Wake counties.

The National Weather Service in North Carolina has confirmed the strength of six different tornadoes that hit the state this weekend. They are working on confirming other possible tornadoes, as teams survey more damaged areas in the state. Two of the tornadoes were powerful EF3s with estimated winds near 160 mph. One of those tornadoes traveled through Hoke, Cumberland and Harnett counties while the other powerhouse traveled through Lee and Wake counties causing damage in their wake. The two EF3s had paths that stretched more than 60 miles, according to the National Weather Service.

A less powerful, but destructive EF2 tornado tracked through Wilson County, while EF1s affected Johnston and southeastern Cumberland and Sampson County. Person County had a touchdown of an EF0 twister.

News stations around the country have been showing footage of the Loews hardware store in Sanford that was completely destroyed. Television footage has shown the collapsed building with lawnmowers still positioned in a straight line outside the store. The roof had been torn off by one of the EF3 tornadoes.

NASA's Aqua satellite captured an infrared image from its Atmospheric Infrared Sounder (AIRS) instrument on Apr. 16 at 18:29 UTC (2:29 p.m. EDT). The image showed very cold, high cloud tops of the strong thunderstorms that spawned tornadoes in North Carolina and Virginia. The coldest cloud tops indicated the strongest storms. Temperatures in those clouds were as cold as or colder than -63 F/-52C.

In Virginia, storms associated with the powerful cold front caused flash flooding, wind damage, downed trees and power outages. There were five deaths reported from the storms. According to Dominion Virginia power, a tornado touched down at the switchyard of a Surry, Va. nuclear power station on Sat night, April 16. The tornado cut electricity and triggered a shutdown of two reactors.

In the animation of GOES satellite imagery, the low pressure center moved through the Ohio Valley as the front pushed east. Ahead of the cold front was a warm front that brought in warm, unstable air from the Gulf of Mexico. As the cold front marched through it triggered the severe weather. The animation of GOES satellite imagery clearly shows the line of clouds associated with the powerful cold front moving though the Carolinas on April 16. By April 18, that line of clouds is still visible in the Atlantic Ocean, hundreds of miles off the U.S. East coast.

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Sunday, April 17, 2011

Geomagnetic Storm Subsiding

UPDATE: A geomagnetic storm that sparked auroras around the Arctic Circle and sent Northern Lights spilling over the Canadian border into the United States on April 12, 2011 is subsiding. NOAA forecasters estimate a 25% chance of more geomagnetic activity during the next 24 hours.

April 12, 2011: A G1-class geomagnetic storm is in progress, sparked by a high-speed solar wind stream which is buffeting Earth's magnetic field. High latitude sky watchers should be alert for auroras.

What is a geomagnetic storm?

The Earth's magnetosphere is created by our magnetic field and protects us from most of the particles the sun emits. When a CME or high-speed stream arrives at Earth it buffets the magnetosphere. If the arriving solar magnetic field is directed southward it interacts strongly with the oppositely oriented magnetic field of the Earth. The Earth's magnetic field is then peeled open like an onion allowing energetic solar wind particles to stream down the field lines to hit the atmosphere over the poles. At the Earth's surface a magnetic storm is seen as a rapid drop in the Earth's magnetic field strength. This decrease lasts about 6 to 12 hours, after which the magnetic field gradually recovers over a period of several days.

For answers to other space weather questions, please visit the Spaceweather Frequently Asked Questions page.

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Friday, April 15, 2011

NASA's Next Generation Space Telescope Marks Key Milestone

The first six of 18 segments that will form NASA's James Webb Space Telescope’s primary mirror for space observations will begin final round-the-clock cryogenic testing this week. These tests will confirm the mirrors will respond as expected to the extreme temperatures of space prior to integration into the telescope's permanent housing structure.

The X-ray and Cryogenic Facility at NASA's Marshall Space Flight Center in Huntsville, Ala. will provide the space-like environment to help engineers measure how well the telescope will image infrared sources once in orbit.

Each mirror segment measures approximately 4.3 feet (1.3 meters) in diameter to form the 21.3 foot (6.5 meters), hexagonal telescope mirror assembly critical for infrared observations. Each of the 18 hexagonal-shaped mirror assemblies weighs approximately 88 pounds (40 kilograms). The mirrors are made of a light and strong metal called beryllium, and coated with a microscopically thin coat of gold to enabling the mirror to efficiently collect light.

"The six flight mirrors sitting ready for cryogenic acceptance tests have been carefully polished to their exact prescriptions," said Helen Cole, project manager for Webb activities at Marshall. "It's taken the entire mirror development team, including all the partners, over eight years of fabrication, polishing and cryogenic testing to get to this point."

During cryogenic testing, the mirrors are subjected to extreme temperatures dipping to minus 415 degrees Fahrenheit (-248C) in a 7,600 cubic-foot (approximately 215 cubic meter) helium-cooled vacuum chamber. This permits engineers to measure in extreme detail how the shape of the mirror changes as it cools. This simulates the actual processes each mirror will undergo as it changes shape over a range of operational temperatures in space.

"This final cryotest is expected to confirm the exacting processes that have resulted in flight mirrors manufactured to tolerances as tight as 20 nanometers, or less than one millionth of an inch," said Scott Texter, Webb Optical Telescope element manager at Northrop Grumman in Redondo Beach, Calif.

A second set of six mirror assemblies will arrive at Marshall in July to begin testing, and the final set of six will arrive during the fall.

The Webb Telescope is NASA's next-generation space observatory and successor to the Hubble Space Telescope. The most powerful space telescope designed, Webb will observe the most distant objects in the universe, provide images of the very first galaxies ever formed and help identify unexplored planets around distant stars. The telescope will orbit approximately one million miles from Earth.

"The Webb telescope continues to make good technological progress," said Rick Howard, JWST Program Director in Washington. "We’re currently developing a new baseline cost and schedule to ensure the success of the program."

The telescope is a combined project of NASA, the European Space Agency and the Canadian Space Agency. Northrop Grumman is the prime contractor under NASA's Goddard Space Flight Center in Greenbelt, Md. Ball Aerospace & Technologies Corp. in Boulder, Colo., is responsible for mirror development. L-3- Tinsley Laboratories Inc. in Richmond, Calif. is responsible for mirror grinding and polishing.

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Thursday, April 14, 2011

Fast-Rotating Asteroid Winks For Astronomer's Camera

Video imaging of newly discovered asteroid 2011 GP59 shows the object appearing to blink on and off about once every four minutes.

Amateur astronomers, including Nick James of Chelmsford, Essex, England, have captured video of the interesting object. James generated this video of GP59 on the night of Monday, April 11. The video, captured with an 11-inch Schmidt-Cassegrain telescope, is a compilation of 137 individual frames, each requiring 30 seconds of exposure. At the time, the asteroid was approximately 3,356,000 kilometers (2,081,000 mile) distant. Since then, the space rock has become something of a darling of the amateur astronomy community, with many videos available.

"Usually, when we see an asteroid strobe on and off like that, it means that the body is elongated and we are viewing it broadside along its long axis first, and then on its narrow end as it rotates ," said Don Yeomans, manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "GP59 is approximately 50 meters [240 feet] long, and we think its period of rotation is about seven-and-a-half minutes. This makes the object's brightness change every four minutes or so."

2011 GP59 was discovered the night of April 8/9 by astronomers with the Observatorio Astronomico de Mallorca in Andalusia, Spain. It will make its closest approach to Earth on April 15 at 19:09 UTC (12:09 p.m. PDT) at a distance just beyond the moon's orbit - about 533,000 kilometers (331,000 miles).

"Although newly discovered, the near-term orbital location of asteroid 2011 GP59 can be accurately plotted," said Yeomans. "There is no possibility of the small space rock entering Earth's atmosphere during this pass or for the foreseeable future."

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.

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Tuesday, April 12, 2011

NASA Announces New Homes for Space Shuttle Orbiters After Retirement

After 30 years of spaceflight, more than 130 missions, and numerous science and technology firsts, NASA's space shuttle fleet will retire and be on display at institutions across the country to inspire the next generation of explorers and engineers.

NASA Administrator Charles Bolden on Tuesday announced the facilities where four shuttle orbiters will be displayed permanently at the conclusion of the Space Shuttle Program.

* Shuttle Enterprise, the first orbiter built, will move from the Smithsonian's National Air and Space Museum Steven F. Udvar-Hazy Center in Virginia to the Intrepid Sea, Air & Space Museum in New York.
* The Udvar-Hazy Center will become the new home for shuttle Discovery, which retired after completing its 39th mission in March.
* Shuttle Endeavour, which is preparing for its final flight at the end of the month will go to the California Science Center in Los Angeles.
* Shuttle Atlantis, which will fly the last planned shuttle mission in June, will be displayed at the Kennedy Space Center Visitor’s Complex in Florida.

"We want to thank all of the locations that expressed an interest in one of these national treasures," Bolden said. "This was a very difficult decision, but one that was made with the American public in mind. In the end, these choices provide the greatest number of people with the best opportunity to share in the history and accomplishments of NASA's remarkable Space Shuttle Program. These facilities we've chosen have a noteworthy legacy of preserving space artifacts and providing outstanding access to U.S. and international visitors."

NASA also announced that hundreds of shuttle artifacts have been allocated to museums and education institutions.

* Various shuttle simulators for the Adler Planetarium in Chicago, the Evergreen Aviation & Space Museum of McMinnville, Ore., and Texas A&M's Aerospace Engineering Department
* Full fuselage trainer for the Museum of Flight in Seattle
* Nose cap assembly and crew compartment trainer for the National Museum of the U.S. Air Force at Wright-Patterson Air Force Base in Ohio
* Flight deck pilot and commander seats for NASA's Johnson Space Center in Houston
* Orbital maneuvering system engines for the U.S. Space and Rocket Center of Huntsville, Ala., National Air and Space Museum in Washington, and Evergreen Aviation & Space Museum

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Thursday, April 7, 2011

Breakthrough Study Confirms Cause of Short Gamma-Ray Bursts

A new supercomputer simulation shows the collision of two neutron stars can naturally produce the magnetic structures thought to power the high-speed particle jets associated with short gamma-ray bursts (GRBs). The study provides the most detailed glimpse of the forces driving some of the universe's most energetic explosions.

The state-of-the-art simulation ran for nearly seven weeks on the Damiana computer cluster at the Albert Einstein Institute (AEI) in Potsdam, Germany. It traces events that unfold over 35 milliseconds -- about three times faster than the blink of an eye.

GRBs are among the brightest events known, emitting as much energy in a few seconds as our entire galaxy does in a year. Most of this emission comes in the form of gamma rays, the highest-energy form of light.

"For the first time, we've managed to run the simulation well past the merger and the formation of the black hole," said Chryssa Kouveliotou, a co-author of the study at NASA's Marshall Space Flight Center in Huntsville, Ala. "This is by far the longest simulation of this process, and only on sufficiently long timescales does the magnetic field grow and reorganize itself from a chaotic structure into something resembling a jet."

GRBs longer than two seconds are the most common type and are widely thought to be triggered by the collapse of a massive star into a black hole. As matter falls toward the black hole, some of it forms jets in the opposite direction that move near the speed of light. These jets bore through the collapsing star along its rotational axis and produce a blast of gamma rays after they emerge. Understanding short GRBs, which fade quickly, proved more elusive. Astronomers had difficulty obtaining precise positions for follow-up studies.

That began to change in 2004, when NASA’s Swift satellite began rapidly locating bursts and alerting astronomers where to look.

"For more than two decades, the leading model of short GRBs was the merger of two neutron stars," said co-author Bruno Giacomazzo at the University of Maryland and NASA's Goddard Space Flight Center in Greenbelt, Md. "Only now can we show that the merger of neutron stars actually produces an ultrastrong magnetic field structured like the jets needed for a GRB."

A neutron star is the compressed core left behind when a star weighing less than about 30 times the sun's mass explodes as a supernova. Its matter reaches densities that cannot be reproduced on Earth -- a single spoonful outweighs the Himalayan Mountains.

The simulation began with a pair of magnetized neutron stars orbiting just 11 miles apart. Each star packed 1.5 times the mass of the sun into a sphere just 17 miles across and generated a magnetic field about a trillion times stronger than the sun's.

In 15 milliseconds, the two neutron stars crashed, merged and transformed into a rapidly spinning black hole weighing 2.9 suns. The edge of the black hole, known as its event horizon, spanned less than six miles. A swirling chaos of superdense matter with temperatures exceeding 18 billion degrees Fahrenheit surrounded the newborn black hole. The merger amplified the strength of the combined magnetic field, but it also scrambled it into disarray.

Over the next 11 milliseconds, gas swirling close to the speed of light continued to amplify the magnetic field, which ultimately became a thousand times stronger than the neutron stars' original fields. At the same time, the field became more organized and gradually formed a pair of outwardly directed funnels along the black hole's rotational axis.

This is exactly the configuration needed to power the jets of ultrafast particles that produce a short gamma-ray burst. Neither of the magnetic funnels was filled with high-speed matter when the simulation ended, but earlier studies have shown that jet formation can occur under these conditions.

"By solving Einstein's relativity equations as never before and letting nature take its course, we've lifted the veil on short GRBs and revealed what could be their central engine," said Luciano Rezzolla, the study's lead author at AEI. "This is a long-awaited result. Now it appears that neutron star mergers inevitably produce aligned jet-like structures in an ultrastrong magnetic field."

The study is available online and will appear in the May 1 edition of The Astrophysical Journal Letters.

The authors note the ultimate proof of the merger model will have to await the detection of gravitational waves -- ripples in the fabric of space-time predicted by relativity. Merging neutron stars are expected to be prominent sources, so the researchers also computed what the model's gravitational-wave signal would look like. Observatories around the world are searching for gravitational waves, so far without success because the signals are so faint.

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Wednesday, April 6, 2011

For NASA's Aquarius, Quest for Salt a Global Endeavor

With more than a few stamps on its passport, NASA's Aquarius instrument on the Argentinian Satélite de Aplicaciones Científicas (SAC)-D spacecraft will soon embark on its space mission to "taste" Earth's salty ocean.

After a journey of development and assembly through NASA facilities; a technology center in Bariloche, Argentina; and testing chambers in Brazil, the Aquarius instrument, set to measure the ocean's surface salinity, recently made the trip from São José dos Campos, Brazil, to California's Vandenberg Air Force Base for final integration and testing before its scheduled launch on June 9.

Aquarius will map the concentration of dissolved salt at the ocean's surface, information that scientists will use to study the ocean's role in the global water cycle and how this is linked to ocean currents and climate. Sea surface temperature has been monitored by satellites for decades, but it is both temperature and salinity that determine the density of the surface waters of the ocean. Aquarius will provide fundamentally new ocean surface salinity data to give scientists a better understanding of the density-driven circulation; how it is tied to changes in rainfall and evaporation, or the melting and freezing of ice; and its effect on climate variability.

"The ocean is essentially Earth's thermostat. It stores most of the heat, and what we need to understand is how do changes in salinity affect the 3-D circulation of the ocean," said Gene Feldman, Aquarius Ground System and Mission Operations manager at NASA's Goddard Space Flight Center, Greenbelt, Md.

The development of the Aquarius mission began more than 10 years ago as a joint effort between Goddard and NASA's Jet Propulsion Laboratory in Pasadena, Calif. In 2008, Goddard engineers completed the Aquarius microwave radiometer instrument, which is the key component for measuring salinity from space.

"The radiometer is the most accurate and stable radiometer built for sensing of Earth from space. It's a one-of-a-kind instrument," said Shannon Rodriguez-Sanabria, a microwave communications specialist at Goddard.

JPL built Aquarius' scatterometer instrument, a microwave radar sensor that scans the ocean's surface to measure the effect wind speed has on the radiometer measurements. The radiometer and scatterometer instruments, along with a 2.5-by-3-meter (8.25-by-10-foot) elliptical antenna reflector and many other systems, have been integrated together at JPL to form the complete Aquarius instrument. Other instruments aboard the SAC-D spacecraft are contributions from Argentina, France, Canada and Italy.

In June 2009, Aquarius was flown via a U.S. Air Force cargo jet to San Carlos de Bariloche, Argentina, a destination known for its natural scenery of blue lakes and verdant mountains, to be integrated with Argentina's SAC-D spacecraft. A year later, the fully assembled spacecraft and all the instruments now referred to as the "Aquarius/SAC-D Observatory" were shipped to Brazil. There, engineers began a nine-month campaign of alignment, electromagnetic, vibration, and thermal vacuum testing to ensure it will survive the rigors of launch and space.

JPL will manage the Aquarius mission through Aquarius' commissioning phase, scheduled to last 45 days after launch. Goddard will then manage the Aquarius instrument operations during the mission. Argentina's Comisión Nacional de Actividades Espaciales (CONAE) will operate the spacecraft and download all of the data collected by Aquarius several times per day. Goddard is responsible for producing the Aquarius science data products. JPL will manage the data archive and distribution to scientists worldwide.

Aquarius will collect data continuously as it flies in a near-polar orbit and circles Earth 14 to 15 times each day. The field of view of the instrument is 390 kilometers (242 miles) wide, and it will provide a global map every seven days. The data will be compiled to generate more accurate monthly averages during the mission, which is designed to last a minimum of three years.

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Tuesday, April 5, 2011

Get Some Quick "Cool" Facts About NASA's Webb Telescope on Video

Interested in learning some quick facts about NASA's next-generation space telescope? NASA has created a short video to show you just how literally "cool" the James Webb Space Telescope really is. For one thing, Webb's infrared detectors will be cryogenically cooled to roughly –370F (-224C)!

In a 4 minute video produced at NASA's Goddard Space Flight Center in Greenbelt, Md., astrophysicist Amber Straughn takes you on a quick journey of facts and images to explain what the Webb will tell us about the cosmos.

Amber provides some amazing images of the Hubble and phenomena that it has seen while answering the question, how will Webb improve on what Hubble has seen? Amber tells viewers how Webb's use of infrared light is going to reveal a lot more than astronomers have ever seen before. She also explains how the Webb telescope can see farther back in space and time, and compares the size of the Webb and Hubble primary mirrors to the height of a person.

What's so cool about the Webb telescope? Amber demonstrates just how cold the temperatures of space are where Webb will orbit (over 1 million miles from the Earth) by dipping flexible rubber surgical tubing into liquid nitrogen. At room temperature, nitrogen is a gas; but is a liquid at very cold temperatures - below -321 Fahrenheit (F)/-196 Celsius (C) similar to what the Webb will experience and can instantly change the structure of the tubing, and Amber proves this by smashing it like glass!

Infrared light is heat radiation, so Webb's detectors also need to be kept very cold. That way, they can detect the faint infrared light given off from objects such as stars that are so far away. To keep the telescope that cold, there's a giant sunshield to reflect away the heat and light from the sun. Objects that the Webb's infrared detectors will observe would appear to our eyes as faint as a child’s night light shining from the surface of the moon!

The video shows artist's concepts of some of the mysteries of the universe Webb telescope hopes to solve, like forming and evolving galaxies, the atmospheres of other planets outside of our solar system, the first stars in the universe, and the birth of stars.

The James Webb Space Telescope is named for the second NASA administrator, James Webb, who was the leader of NASA during the Apollo Moon program. The Webb telescope is a collaborative effort between NASA, the European Space Agency and the Canadian Space Agency.

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Monday, April 4, 2011

The End of a Remarkable Mission: SeaWiFS’ Thirteen Years of Observing our Home Planet

Mary Cleave left the NASA astronaut corps in the early 1990s to make a rare jump from human spaceflight to Earth science. She was going to work on an upcoming mission to measure gradations in ocean color – something she had actually seen from low-Earth orbit with her own eyes. From space, differing densities of phytoplankton and algae and floating bits of plant life reveal themselves as so many blues and greens. For Cleave, a former environmental engineer, the attraction was simple.

"We were going to measure green slime on a global scale," said Cleave, now retired from her varied NASA career.

That is exactly what SeaWiFS – Sea-viewing Wide Field-of-view-Sensor – did for over 13 years, until it recently stopped communicating with ground-based data stations and after several months of intensive efforts at recovery, was declared unrecoverable in February. This seemingly simple measurement offers a window into the oceans’ basic ability to support life. SeaWiFS’ long, well-calibrated data record gives scientists one of the best benchmarks available to study the planet’s biological response to a changing environment.

The OrbView-2 spacecraft, which carried the SeaWiFS instrument, stopped communicating with Earth-based data stations in December 2010. After several months of attempts to revive the link, GeoEye, the company that operated the spacecraft, officially ended any further attempts at recovery. SeaWiFS was NASA’s first "data buy" mission, in which a private company, Orbital Sciences, designed and built the instrument and spacecraft to NASA specifications and NASA agreed to purchase the data as long at it met its scientific requirements. Like all spacecraft, the one that carried SeaWiFS had several fundamental back-up systems, which allowed the spacecraft to operate well past its planned five-year mission life.

"The hope was to induce it to go into 'Phoenix mode' – a self-protective state, that would have allowed the ground controllers to recover the spacecraft. Unfortunately they were never able to get a return signal and without the ability to communicate with it, chances for recovery faded," said Gene Carl Feldman, SeaWiFS project manager, based at NASA's Goddard Space Flight Center, Greenbelt, Md. "Unfortunately, we'll never absolutely know what went wrong. Many people said it would never get off the ground. Some said it wouldn’t last a year. The mission was planned for five years. We got 13 years of incredible data out of this amazing little satellite."

For centuries, oceanographers were limited in their study of the highly variable and incredibly vast ocean by what they could physically sample from the deck of a slow moving ship. Like so many scientific fields, satellites changed that. The oceans, once thought homogenous and boring, have been revealed as far more dynamic, changing and varied from region to region and season to season. Quantifying this diversity in time and space would be impossible without long-operating satellites. Since its launch in 1997, SeaWiFS has been making outsized contributions to the field of observing the oceans pulse with life through changing seasons and a changing climate.

SeaWiFS was designed to measure ocean color. This seemingly narrow measurement captures the fundamental biological activity at the ocean surface, the surging and depleting life cycle of phytoplankton, the microscopic floating ocean plant life. Phytoplankton forms the base of the oceanic food web, and its abundance is a direct indicator of the seas’ ability to support life. It also plays a central role in the oceans’ carbon uptake, a key component of the planet’s climate system, particularly as the level of carbon dioxide in the atmosphere continues to increase. SeaWiFS was used to offer real-time monitoring of red tides and other harmful algae, which can bloom in polluted waters and be deadly to fish and oysters. Ocean color also offers a window into the constantly changing interplay between the ocean’s physical and chemical processes such as temperature and nutrient levels, the atmosphere and the biological life of the seas.

Feldman remembers watching the first dramatic example of SeaWiFS ability to capture this unfold. The satellite reached orbit and starting collecting data during the middle of the 1997-98 El Niño. An El Niño typically suppresses nutrients in the surface waters, critical for phytoplankton growth and keeps the ocean surface in the equatorial Pacific relatively barren.

Then in the spring of 1998, as the El Niño began to fade and trade winds picked up, the equatorial Pacific Ocean bloomed with life, changing "from a desert to a rain forest," in Feldman’s words, in a matter of weeks. "Thanks to SeaWiFS, we got to watch it happen," he said. "It was absolutely amazing – a plankton bloom that literally spanned half the globe."

Originally designed to measure only ocean plant life, modifications made to SeaWiFS before launch allowed it to make a similar kind of measurement of plant color on land. This ability to see all of the planet’s plant life with a single, well-calibrated instrument produced a first-of-its-kind snapshot of the Earth’s biosphere in 1998. Then-Vice President Al Gore was so impressed he asked for a poster of the image to hang in his office, Feldman said.

From the broadest perspective, Feldman sees this measurement as an observation of what makes Earth different from all the other celestial bodies NASA studies. "None of the other planets we have studied so far seem to have the combination of factors that result in life. We do. That SeaWiFS image of the global biosphere is the picture of the things that set us apart."

But the mission’s lasting contribution will no doubt be its study of the life of the oceans. This record stretches over a long enough period to produce a critical record of both natural variability and the planet’s biological response to a changing climate.

Given the length and breadth of the SeaWiFS data record, it may help oceanographers test this question of just how resilient the oceans are. SeaWiFS has observed a decline in plant life productivity in some of the larger "gyres," large-scale ocean current patterns, said Jim Yoder, a senior scientist at Woods Hole Oceanographic Institute, Woods Hole, Mass. who also worked on ocean color at NASA in two different stints in the 1980s and 1990s. It’s the kind of observation over time a satellite can make, and it has created a debate in ocean science circles about whether this is a natural cycle or an effect of climate change.

"Everyone who looks at the data sees the decline, it’s just a question of why," Yoder said. "This has set off a lot of interest and debate. The climate implication would be the global ocean is declining in productivity due to increasing temperatures, which suppresses nutrients so there is less phytoplankton. Is it a cycle or is it a trend? Part of SeaWiFS’ legacy may be related to trying to resolve this. You can’t do that if your global change data has gaps between years and different satellites."

Cleave, a Space Shuttle astronaut who had been an environmental engineer with the Utah Water Research Laboratory before joining the astronaut corps, is one of the few people to have seen ocean color gradations from space with her own eyes.

"It really is amazing and beautiful," said, Cleave, who worked as SeaWiFS project manager for much of the 1990s before becoming NASA’s Associate Administrator for the Science Mission Directorate, NASA Headquarters, Washington. She retired in 2007. "You can see plants growing in the ocean, which is basically what ocean color is. Particularly around the mouths of big, dirty rivers."

Cleave was drawn to questions about both ocean and land plants’ role in the global carbon cycle. How much carbon dioxide were the aquatic plants drawing from the atmosphere for photosynthesis? How much were land plants using? Before SeaWiFS, this fundamental question wasn’t answered. With its ability to measure both land and ocean primary productivity, SeaWiFS also revealed to scientists the balance between the two as a percentage of global plant life.

"Turns out it’s about 50-50," Cleave said. "But that’s something we didn’t know."

NASA continues to make ocean color measurements with its MODIS (MODerate resolution Imaging Spectroradiometer) instruments. Others have followed on in recognizing the importance of ocean color observations both for understanding the global carbon cycle and more immediate societal benefits such as monitoring harmful algae and helping commericial fisheries locate potential feeding grounds. Since the launch of SeaWiFS, the Indian Space Research Organization has launched its Oceansat satellites and the European Space Agency launched Envisat, which measures ocean color with its MERIS (Medium-resolution Imaging Spectrometer) instrument.

Yoder said SeaWiFS has made great contributions, but its ultimate legacy remains unwritten. Scientists will likely use its data record for decades, both for new research and as a baseline to measure the biosphere’s response to climate change.

"It’s hard to pin this down, but it changed the field of biological productivity from one that focused on individual bays or estuaries. It changed the field from a local to global perspective. Until then you didn’t have that ability."

Said Feldman, "The international scientific community certainly could not have asked for a more tenacious little spacecraft and instrument that has served us so well for the past 13-plus years. There is no question that the Earth is changing. SeaWiFS enabled us for the first time to monitor the biological consequences of that change - to see how the things we do, and how natural variability, affect the Earth's ability to support life."

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Sunday, April 3, 2011

NASA Test Stand Passes Review for Next-Generation Rocket Engine Testing

Forty-five years after its first Saturn V rocket stage test and 35 years after its first space shuttle main engine test, the A-2 Test Stand at NASA’s John C. Stennis Space Center achieved a milestone in preparation for its third major rocket engine test project.

A facility readiness review in mid-March indicated all major modifications have been completed on the historic A-2 stand to begin testing the next-generation J-2X rocket engine this summer.

The new test project comes as Stennis celebrates its 50th anniversary year. On Oct. 26, 1961, NASA publicly announced plans to build the south Mississippi facility to test the massive Saturn V rocket stages for the Apollo Program.

The first test of a Saturn V second stage at Stennis was performed at the A-2 stand on April 23, 1966. Stennis engineers tested 27 first and second Saturn V rocket stages for the Apollo Program, including those used to carry humans to the moon.

In the mid-1970s, the stand was modified from Apollo Program parameters to allow testing of space shuttle main engines. The first space shuttle main engine test on the A-2 stand was conducted 35 years ago, on March 31, 1976. In ensuing decades, Stennis engineers tested space shuttle main engines used to power more than 130 missions. The last scheduled space shuttle main engine test was performed on the A-2 stand in July 2009.

After a decommissioning period, Stennis employees spent 10 months converting the A-2 stand from space shuttle main engine parameters to those needed for the new engine test series. The March 16-17 facility readiness review identified no major actions, which means the A-2 Test Stand is ready to receive the J-2X engine and begin checkout testing activation of engine critical systems. Stand employees now will work through the final items to be completed before installation of a J-2X engine in early June.

"Some of the hardware was decades old and nearing the end of its serviceability," said Gary Benton, manager of the J-2X engine testing project at Stennis. "Also, the J-2X has different testing requirements than the space shuttle main engine. It was a major transition completed on a very demanding schedule."

The transition work from the space shuttle main engine project to the J-2X test project included structural, electrical and plumbing modifications to accommodate the different geometry of the J-2X engine, and included the installation of a new J-2X engine start system. Liquid oxygen and liquid hydrogen transfer lines that dated back to the 1960s also were replaced, as was other piping on the stand. Control systems also were upgraded on the stand.

The J-2X engine is being developed by Pratt & Whitney Rocketdyne for NASA as a next-generation engine that can carry humans beyond low-Earth orbit to deep space. Engineers at NASA's Marshall Space Flight Center in Huntsville, Ala., manage J-2X engine development. Stennis is preparing three stands to test the new engine. Power pack testing is scheduled on the A-1 Test Stand. Verification and sea-level testing will be conducted on the A-2 Test Stand. The A-3 Test Stand under construction and set for activation in 2013 will allow operators to test new engines at simulated altitudes up to 100,000 feet, a critical requirement for a deep space engine.

Plans now are to install a J-2X research-and-development engine on the A-2 Test Stand this summer. Testing will begin soon afterward and continue throughout the year. Various verification and start-sequence tests will be performed.

"This is the future for American space exploration," Benton said. "We are excited to play a key part in the progress of the nation's space program."

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Friday, April 1, 2011

The Art of Making Stars

It might look like an abstract painting, but this splash of colors is in fact a busy star-forming complex called Rho Ophiuchi. NASA's Wide-field Infrared Explorer, or WISE, captured the picturesque image of the region, which is one of the closest star-forming complexes to Earth.

The amazing variety of colors seen in this image represents different wavelengths of infrared light. The bright white nebula in the center of the image is glowing due to heating from nearby stars, resulting in what is called an emission nebula. The same is true for most of the multi-hued gas prevalent throughout the entire image, including the bluish, bow-shaped feature near the bottom right. The bright red area in the bottom right is light from the star in the center – Sigma Scorpii – that is reflected off of the dust surrounding it, creating what is called a reflection nebula. And the much darker areas scattered throughout the image are pockets of cool, dense gas that block out the background light, resulting in absorption (or 'dark') nebulae. WISE's longer wavelength detectors can typically see through dark nebulae, but these are exceptionally opaque.

JPL manages and operates the Wide-field Infrared Survey Explorer 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.

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