First Ever STEREO Images of the Entire Sun

On Feb. 6th, NASA's twin STEREO probes moved into position on opposite sides of the sun, and they are now beaming back uninterrupted images of the entire star—front and back.

"For the first time ever, we can watch solar activity in its full 3-dimensional glory," says Angelos Vourlidas, a member of the STEREO science team at the Naval Research Lab in Washington, DC.

"This is a big moment in solar physics," says Vourlidas. "STEREO has revealed the sun as it really is--a sphere of hot plasma and intricately woven magnetic fields."

Each STEREO probe photographs half of the star and beams the images to Earth. Researchers combine the two views to create a sphere. These aren't just regular pictures, however. STEREO's telescopes are tuned to four wavelengths of extreme ultraviolet radiation selected to trace key aspects of solar activity such as flares, tsunamis and magnetic filaments. Nothing escapes their attention.

IBEX Spacecraft Finds Discoveries Close to Home

Imagine floating 35,000 miles above the sunny side of Earth. Our home planet gleams below, a majestic whorl of color and texture. All seems calm around you. With no satellites or space debris to dodge, you can just relax and enjoy the black emptiness of space.

But looks can be deceiving.

In reality, you've unknowingly jumped into an invisible mosh pit of electromagnetic mayhem — the place in space where a supersonic "wind" of charged particles from the Sun crashes head-on into the protective magnetic bubble that surrounds our planet. Traveling at a million miles per hour, the solar wind's protons and electrons sense Earth's magnetosphere too late to flow smoothly around it. Instead, they're shocked, heated, and slowed almost to a stop as they pile up along its outer boundary, the magnetopause, before getting diverted sideways.

Space physicists have had a general sense of these dynamic goings-on for decades. But it wasn't until the advent of the Interstellar Boundary Explorer or IBEX, a NASA spacecraft launched in October 2008, that they've been able to see what the human eye cannot: the first-ever images of this electromagnetic crash scene. They can now witness how some of the solar wind's charged particles are being neutralized by gas escaping from Earth's atmosphere.

A New Way to See Atoms

IBEX wasn't designed to keep tabs on Earth's magnetosphere. Instead, its job is to map interactions occurring far beyond the planets, 8 to 10 billion miles away, where the Sun's own magnetic bubble, the heliosphere, meets interstellar space.

IBEX found that Energetic Neutral Atoms, or ENAs, are coming from a region just outside Earth's magnetopause where nearly stationary protons from the solar wind interact with the tenuous cloud of hydrogen atoms in Earth's exosphere. Credit: NASA/Goddard Space Flight Center

Only two spacecraft, Voyagers 1 and 2, have ventured far enough to probe this region directly. IBEX, which travels in a looping, 8-day-long orbit around Earth, stays much closer to home, but it carries a pair of detectors that can observe the interaction region from afar.

Here's how: When fast-moving protons in the solar wind reach the edge of the heliosphere, they sometimes grab electrons from the slower-moving interstellar atoms around them, like batons getting passed between relay runners. This charge exchange creates electrically neutral hydrogen atoms that are no longer controlled by magnetic fields. Suddenly, they're free to go wherever they want — and because they're still moving fast, they quickly zip away from the interstellar boundary in all directions.

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This animation shows a neutral solar particle's path leaving the Sun, following the magnetic field lines out to the Heliosheath. The solar particle hits a hydrogen atom, stealing it's electron and we follow it until we see it hit one of IBEXs detectors. Credit: NASA/Goddard Space Flight Center

Some of these "energetic neutral atoms," or ENAs, zip past Earth, where they're recorded by IBEX. Its two detectors don't take pictures with conventional optics. Instead, they record the number and energy of atoms arriving from small spots of sky about 7 degrees across (the apparent size of a tennis ball held at arm's length). Because its spin axis always points at the Sun, the spacecraft slowly turns throughout Earth's orbit and its detectors scan overlapping strips that create a complete 360 degrees map every six months.

A Collision Zone Near Earth

Because IBEX is orbiting Earth, it also has a front-row seat for observing the chaotic pileup of solar-wind particles occurring along the "nose" of Earth's magnetopause, about 35,000 miles out. ENAs are created there too, as solar-wind protons wrest electrons from hydrogen atoms in the outermost vestiges of our atmosphere, the exosphere.

Other spacecraft have attempted to measure the density of the dayside exosphere, without much success. NASA's Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft probably detected ENAs from this region a decade ago, but its detectors didn't have the sensitivity to pinpoint or measure the source.

Now, thanks to IBEX, we know just how tenuous the outer exosphere really is. "Where the interaction is strongest, there are only about eight hydrogen atoms per cubic centimeter," explains Stephen A. Fuselier, the Lockheed Martin Space Systems researcher who led the mapping effort. His team's results appear in the July 8 issue of Geophysical Research Letters.

The key observations were made in March and April 2009, when IBEX was located far from Earth — about halfway to the Moon's orbit — and its detectors could scan the region directly in front of the magnetopause. During some of the March observations, the European Space Agency's Cluster 3 spacecraft was positioned just in front of the magnetopause, where it measured the number of deflected solar-wind protons directly. "Cluster played a very important role in this study," Fuselier explains. "It was in the right place at the right time."

Artist concept of the IBEX satellite. Credit: NASA/Goddard Space Flight Center

The new IBEX maps show that the ENAs thin out at locations away from the point of peak intensity. This falloff makes sense, Fuselier says, because Earth's magnetopause isn't spherical. Instead, it has a teardrop shape that's closest to Earth at its nose but farther away everywhere else. So at locations well away from the magnetopause's centerline, even fewer of the exosphere's hydrogen atoms are hanging around to interact with the solar wind. "No exosphere, no ENAs," he explains.

A Versatile Spacecraft

Since its launch, IBEX has also scanned another nearby world, with surprising results. The moon has no atmosphere or magnetosphere, so the solar wind slams unimpeded into its desolate surface. Most of those particles get absorbed by lunar dust. In fact, space visionaries wonder if the moon's rubbly surface has captured enough helium-3, an isotope present in tiny amounts in the Sun's outflow, to serve as a fuel for future explorers.

Yet cosmic chemists have long thought that some solar-wind protons must be bouncing off the lunar surface, becoming ENAs through charge exchange as they do. So does the moon glow in IBEX's scans? Indeed it does, says David J. McComas of Southwest Research Institute in San Antonio, Texas, who serves as the mission's Principal Investigator.

In a report published last year in Geophysical Research Letters, McComas and other researchers conclude that about 10 percent of the solar-wind particles striking the Moon escape to space as ENAs detectable by IBEX. That amounts to roughly 150 tons of recycled hydrogen atoms per year.

Meanwhile, the squat, eight-sided spacecraft continues its primary task of mapping the interactions between the outermost heliosphere and the interstellar medium that lies beyond. McComas and his team are especially eager to learn more about the mysterious and unexpected "ribbon" of ENAs that turned up in the spacecraft's initial all-sky map.

At NASA's Goddard Space Flight Center in Greenbelt, Md., IBEX Mission Scientist Robert MacDowall says the spacecraft should be able to continue its observations through at least 2012. "We weren't sure those heliospheric interactions would vary with time, but they do," he explains, "and it's great that IBEX will be able to record them for years to come."

For more information visit http://www.nasa.gov/mission_pages/ibex/em-crash.html

NASA Telescope Finds Elusive Buckyballs in Space

PASADENA, Calif. -- Astronomers using NASA's Spitzer Space Telescope have discovered carbon molecules, known as "buckyballs," in space for the first time. Buckyballs are soccer-ball-shaped molecules that were first observed in a laboratory 25 years ago.

They are named for their resemblance to architect Buckminster Fuller's geodesic domes, which have interlocking circles on the surface of a partial sphere. Buckyballs were thought to float around in space, but had escaped detection until now.

"We found what are now the largest molecules known to exist in space," said astronomer Jan Cami of the University of Western Ontario, Canada, and the SETI Institute in Mountain View, Calif. "We are particularly excited because they have unique properties that make them important players for all sorts of physical and chemical processes going on in space." Cami has authored a paper about the discovery that will appear online Thursday in the journal Science.

Buckyballs are made of 60 carbon atoms arranged in three-dimensional, spherical structures. Their alternating patterns of hexagons and pentagons match a typical black-and-white soccer ball. The research team also found the more elongated relative of buckyballs, known as C70, for the first time in space. These molecules consist of 70 carbon atoms and are shaped more like an oval rugby ball. Both types of molecules belong to a class known officially as buckminsterfullerenes, or fullerenes.

The Cami team unexpectedly found the carbon balls in a planetary nebula named Tc 1. Planetary nebulas are the remains of stars, like the sun, that shed their outer layers of gas and dust as they age. A compact, hot star, or white dwarf, at the center of the nebula illuminates and heats these clouds of material that has been shed.

The buckyballs were found in these clouds, perhaps reflecting a short stage in the star's life, when it sloughs off a puff of material rich in carbon. The astronomers used Spitzer's spectroscopy instrument to analyze infrared light from the planetary nebula and see the spectral signatures of the buckyballs. These molecules are approximately room temperature -- the ideal temperature to give off distinct patterns of infrared light that Spitzer can detect. According to Cami, Spitzer looked at the right place at the right time. A century from now, the buckyballs might be too cool to be detected.

The data from Spitzer were compared with data from laboratory measurements of the same molecules and showed a perfect match.

NASA's Spitzer Space Telescope has at last found buckyballs in space, as illustrated by this artist's conception showing the carbon balls coming out from the type of object where they were discovered. Image credit: NASA/JPL-Caltech

"We did not plan for this discovery," Cami said. "But when we saw these whopping spectral signatures, we knew immediately that we were looking at one of the most sought-after molecules."

In 1970, Japanese professor Eiji Osawa predicted the existence of buckyballs, but they were not observed until lab experiments in 1985. Researchers simulated conditions in the atmospheres of aging, carbon-rich giant stars, in which chains of carbon had been detected. Surprisingly, these experiments resulted in the formation of large quantities of buckminsterfullerenes. The molecules have since been found on Earth in candle soot, layers of rock and meteorites.

The study of fullerenes and their relatives has grown into a busy field of research because of the molecules' unique strength and exceptional chemical and physical properties. Among the potential applications are armor, drug delivery and superconducting technologies.

These data from NASA's Spitzer Space Telescope show the signatures of buckyballs in space. Image credit: NASA/JPL-Caltech/University of Western Ontario

Sir Harry Kroto, who shared the 1996 Nobel Prize in chemistry with Bob Curl and Rick Smalley for the discovery of buckyballs, said, "This most exciting breakthrough provides convincing evidence that the buckyball has, as I long suspected, existed since time immemorial in the dark recesses of our galaxy."

Previous searches for buckyballs in space, in particular around carbon-rich stars, proved unsuccessful. A promising case for their presence in the tenuous clouds between the stars was presented 15 years ago, using observations at optical wavelengths. That finding is awaiting confirmation from laboratory data. More recently, another Spitzer team reported evidence for buckyballs in a different type of object, but the spectral signatures they observed were partly contaminated by other chemical substances.

For more information visit http://www.nasa.gov/mission_pages/spitzer/news/spitzer20100722.html

Hyperfast Star Was Booted From Milky Way

A hundred million years ago, a triple-star system was traveling through the bustling center of our Milky Way galaxy when it made a life-changing misstep. The trio wandered too close to the galaxy's giant black hole, which captured one of the stars and hurled the other two out of the Milky Way. Adding to the stellar game of musical chairs, the two outbound stars merged to form a super- hot, blue star.

This story may seem like science fiction, but astronomers using NASA's Hubble Space Telescope say it is the most likely scenario for a so-called hypervelocity star, known as HE 0437-5439, one of the fastest ever detected. It is blazing across space at a speed of 1.6 million miles (2.5 million kilometers) an hour, three times faster than our Sun's orbital velocity in the Milky Way. Hubble observations confirm that the stellar speedster hails from the Milky Way's core, settling some confusion over where it originally called home.

Most of the roughly 16 known hypervelocity stars, all discovered since 2005, are thought to be exiles from the heart of our galaxy. But this Hubble result is the first direct observation linking a high-flying star to a galactic center origin.

"Using Hubble, we can for the first time trace back to where the star comes from by measuring the star's direction of motion on the sky. Its motion points directly from the Milky Way center," says astronomer Warren Brown of the Harvard- Smithsonian Center for Astrophysics in Cambridge, Mass., a member of the Hubble team that observed the star. "These exiled stars are rare in the Milky Way's population of 100 billion stars. For every 100 million stars in the galaxy lurks one hypervelocity star."

This illustration shows one possible mechanism for how the star HE 0437-5439 acquired enough energy to be ejected from our Milky Way galaxy. In this scenario, a triple-star system, consisting of a close binary system and another outer member bound to the group, is orbiting near the galaxy's monster black hole. One star is captured by the black hole and the tightly bound pair gets ejected from the galaxy. As the duo speeds through the galaxy, one member evolves more quickly and consumes the other. The resulting rejuvenated star, massive and very blue, is called a blue straggler. Credit: NASA, ESA, and A. Feild (STScI)

The movements of these unbound stars could reveal the shape of the dark matter distribution surrounding our galaxy. "Studying these stars could provide more clues about the nature of some of the universe's unseen mass, and it could help astronomers better understand how galaxies form," says team leader Oleg Gnedin of the University of Michigan in Ann Arbor. "Dark matter's gravitational pull is measured by the shape of the hyperfast stars' trajectories out of the Milky Way."

The stellar outcast is already cruising in the Milky Way's distant outskirts, high above the galaxy's disk, about 200,000 light-years from the center. By comparison, the diameter of the Milky Way's disk is approximately 100,000 light- years. Using Hubble to measure the runaway star's direction of motion and determine the Milky Way's core as its starting point, Brown and Gnedin's team calculated how fast the star had to have been ejected to reach its current location.

"The star is traveling at an absurd velocity, twice as much as the star needs to escape the galaxy's gravitational field," explains Brown, a hypervelocity star hunter who found the first unbound star in 2005. "There is no star that travels that quickly under normal circumstances-something exotic has to happen."

The hot, blue star HE 0437-5439 has been tossed out of the center of our Milky Way galaxy with enough speed to escape the galaxy's gravitational clutches. The stellar outcast is rocketing through the Milky Way's distant outskirts at 1.6 million miles an hour, high above the galaxy's disk, about 200,000 light-years from the center. The star is destined to roam intergalactic space. Credit: NASA, ESA, and G. Bacon (STScI)

There's another twist to this story. Based on the speed and position of HE 0437- 5439, the star would have to be 100 million years old to have journeyed from the Milky Way's core. Yet its mass - nine times that of our Sun - and blue color mean that it should have burned out after only 20 million years - far shorter than the transit time it took to get to its current location.

The most likely explanation for the star's blue color and extreme speed is that it was part of a triple-star system that was involved in a gravitational billiard-ball game with the galaxy's monster black hole. This concept for imparting an escape velocity on stars was first proposed in 1988. The theory predicted that the Milky Way's black hole should eject a star about once every 100,000 years.

Brown suggests that the triple-star system contained a pair of closely orbiting stars and a third outer member also gravitationally tied to the group. The black hole pulled the outer star away from the tight binary system. The doomed star's momentum was transferred to the stellar twosome, boosting the duo to escape velocity from the galaxy. As the pair rocketed away, they went on with normal stellar evolution. The more massive companion evolved more quickly, puffing up to become a red giant. It enveloped its partner, and the two stars spiraled together, merging into one superstar - a blue straggler.

"While the blue straggler story may seem odd, you do see them in the Milky Way, and most stars are in multiple systems," Brown says.

Compass/Scale Image of Hypervelocity Star HE 0437-5439 Credit: NASA, ESA, and Z. Levay (STScI)

This vagabond star has puzzled astronomers since its discovery in 2005 by the Hamburg/European Southern Observatory sky survey. Astronomers had proposed two possibilities to solve the age problem. The star either dipped into the Fountain of Youth by becoming a blue straggler, or it was flung out of the Large Magellanic Cloud, a neighboring galaxy.

In 2008 a team of astronomers thought they had solved the mystery. They found a match between the exiled star's chemical makeup and the characteristics of stars in the Large Magellanic Cloud. The rogue star's position also is close to the neighboring galaxy, only 65,000 light-years away. The new Hubble result settles the debate over the star's birthplace.

Astronomers used the sharp vision of Hubble's Advanced Camera for Surveys to make two separate observations of the wayward star 3 1/2 years apart. Team member Jay Anderson of the Space Telescope Science Institute in Baltimore, Md., developed a technique to measure the star's position relative to each of 11 distant background galaxies, which form a reference frame.

Anderson then compared the star's position in images taken in 2006 with those taken in 2009 to calculate how far the star moved against the background galaxies. The star appeared to move, but only by 0.04 of a pixel (picture element) against the sky background. "Hubble excels with this type of measurement," Anderson says. "This observation would be challenging to do from the ground."

Location of Hypervelocity Star HE 0437-5439 Credit: NASA, ESA, and Z. Levay (STScI)

The team is trying to determine the homes of four other unbound stars, all located on the fringes of the Milky Way.

"We are targeting massive 'B' stars, like HE 0437-5439," says Brown, who has discovered 14 of the 16 known hypervelocity stars. "These stars shouldn't live long enough to reach the distant outskirts of the Milky Way, so we shouldn't expect to find them there. The density of stars in the outer region is much less than in the core, so we have a better chance to find these unusual objects."

The results were published online in The Astrophysical Journal Letters on July 20, 2010. Brown is the paper's lead author.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc. in Washington, D.C.

For more information visit http://www.nasa.gov/mission_pages/hubble/science/expelled-star.html

NASA Retires TRACE Spacecraft After Highly Successful Mission

NASA's Transition Region And Coronal Explorer, known as TRACE, conducted its final observations of the sun on June 21.

Although launched on April Fools' Day, 1998, TRACE quickly proved its worth, observing – for the first time - an entire cycle of solar activity and imaging dynamic coronal phenomena.

TRACE provided images at five times the magnification of those taken by the Extreme Ultraviolet Imaging Telescope Instrument aboard the Solar and Heliospheric Observatory (SOHO).

TRACE spacecraft from video

Many details of the fine structure of the corona were observed for the first time. Early in its mission, it discovered the fine-scale magnetic features where enhanced heating occurs at the footpoints of coronal loop systems in solar active regions, which later became known as "coronal moss."

In 2001, TRACE observations of astonishing coronal activity were highlighted in the IMAX movie SolarMax.

High spatial resolution observations of the solar corona are now being carried out by NASA''s newest eye on the sun, the Solar Dynamics Observatory, a Goddard-built spacecraft managed by the Science Mission Directorate's Heliophysics Division. SDO's field of view is much larger than TRACE, so that the entire disk of the sun, not a small area, is imaged in every observation.

The TRACE spacecraft observes an X-ray flare over solar active region AR9906, April 21, 2002.

Lockheed-Martin Solar and Astrophysics Laboratory in Palo Alto, Calif., developed the TRACE instrument and NASA Goddard Space Flight Center's Flight Projects Directorate designed and built this Small Explorer class spacecraft. The entire mission was accomplished for $10M under budget.

During its 12 year mission, TRACE produced millions of stunning images and contributed to more than 1,000 scientific publications.

Congratulations to TRACE mission team and numerous other scientists and engineers who contributed the mission’s outstanding success.

For more information visit http://www.nasa.gov/topics/solarsystem/sunearthsystem/main/trace-retires.html

Voyager 2 at 12,000 Days: The Super-Marathon Continues

NASA's plucky Voyager 2 spacecraft has hit a long-haul operations milestone today (June 28) -- operating continuously for 12,000 days. For nearly 33 years, the venerable spacecraft has been returning data about the giant outer planets, and the characteristics and interaction of solar wind between and beyond the planets. Among its many findings, Voyager 2 discovered Neptune's Great Dark Spot and its 450-meter-per-second (1,000-mph) winds.

The two Voyager spacecraft have been the longest continuously operating spacecraft in deep space. Voyager 2 launched on August 20, 1977, when Jimmy Carter was president. Voyager 1 launched about two weeks later on Sept. 5. The two spacecraft are the most distant human-made objects, out at the edge of the heliosphere -- the bubble the sun creates around the solar system. Mission managers expect Voyager 1 to leave our solar system and enter interstellar space in the next five years or so, with Voyager 2 on track to enter interstellar space shortly after that.

This artist's rendering depicts NASAs Voyager 2 spacecraft as it studies the outer limits of the heliosphere - a magnetic 'bubble' around the solar system that is created by the solar wind. Image credit: NASA/JPL-Caltech.

Having traveled more than 21 billion kilometers (13 billion miles) on its winding path through the planets toward interstellar space, the spacecraft is now nearly 14 billion kilometers (9 billion miles) from the sun. A signal from the ground, traveling at the speed of light, takes about 12.8 hours one-way to reach Voyager 2.

This image of the official Voyager clock, taken today, June 28, 2010, at NASA's Jet Propulsion Laboratory, shows that NASA's Voyager 2 spacecraft has been operating continuously for 12,000 days. The Voyager clock is kept at JPL. Image Credit: NASA/JPL-Caltech.

Voyager 1 will reach this 12,000-day milestone on July 13, 2010 after traveling more than 22 billion kilometers (14 billion miles). Voyager 1 is currently more than 17 billion kilometers (11 billion miles) from the sun.

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

For more information about the Voyagers, visit: http://voyager.jpl.nasa.gov/.

For more information visit http://www.nasa.gov/mission_pages/voyager/voyager20100628.html

Oil Offshore of Alabama and Florida's Western Panhandle

The possibility of detecting oil slicks in photo-like satellite images depends on the slick being located in the sunglint region—the wide, washed-out strip where the mirror-like reflection of the Sun off the water is diffused by waves and currents. When the oil is located in that relatively narrow region of the scene, it can strongly influence how the water reflects light. Oil-covered water may look dramatically brighter or darker than adjacent, oil-free water.

In this image from Sunday, June 27, 2010, eastern areas of the slick are more visible than western areas, even though analysis from the National Oceanic and Atmospheric Administration indicates heavy concentrations of oil in the vicinity of the leaking well, which is about 75 kilometers (47 miles) southeast of the Mississippi Delta (beyond the left edge of the image). Ribbons of silvery-gray oil swirl in the waters off Alabama and Florida, while farther west—closer to the source of the leak—the reflection seems to be dominated by muddy water in the Mississippi River Delta.

Although the oil extent does change from day to day, the big difference in the appearance of oil in this image versus the previous day’s image is the location of the oil in relation to the sunglint region. In this view from June 27, the sunglint fell across an area farther east than it did in the image from June 26, and so the oil is more visible there. Image Credit: NASA MODIS Rapid Response Team

Text credit: Rebecca Lindsey/NASA's Earth Observatory/NASA's Goddard Space Flight Center

For more information visit http://www.nasa.gov/topics/earth/features/oilspill/20100628_oil.html

The Earth From The Moon

All cameras are susceptible to scattered light. You may have seen scattered light in pictures you have taken looking towards the Sun. Sunlight reflects off the optics and sometimes off the structure of the lens, and often appears as a gradient of brightness across the image. Attaching a baffle to your camera, like we did with the LROC Wide and Narrow Angle Cameras, can minimize this effect. More subtle effects are often present but usually you simply just don't notice artifacts because of strong color contrasts in the scene.

Since the Moon has only very small color contrasts, the LROC team must characterize even subtle scattered light effects within the 7-color Wide Angle Camera (WAC) images. Changes in composition (rock types) result in subtle differences of color, typically about 10% or less. For scientists to make accurate interpretations of WAC color maps, the amount of scattered light must be quantified (and preferably corrected). One way of measuring scattered light is imaging a bright object against a dark background. From the Moon, the Earth serves that function well.

While a series of WAC calibration images of the Earth were being acquired, the Narrow Angle Camera (NAC) was shuttered to capture this spectacular Earth view. The bottom of the Earth was clipped because the prediction of the exact time when the cameras' fields of view would cross the Earth was off by a few seconds.

The Earth as seen from the Moon! LROC NAC mosaic of images snapped on 12 June 2010 during a calibration sequence (Images E130954785L and E130954785R). Credit: NASA/Goddard/Arizona State University

Since the NAC acquires only one line of a picture at a time, the spacecraft had to be nodded across the Earth to build up the scene. The NAC Earth view is actually a mosaic of NAC-Left and NAC-Right images put together after calibration. The distance between the Moon and the Earth was 372,335 km when the picture was taken, with a pixel scale of about 3.7 km, and the center of this view of Earth is 25°N latitude, 114°E longitude (a few hundred kilometers north of Hong Kong).

It was a beautiful clear summer day over the North Pole. You can see ice covering most of the Arctic Ocean with a few leads of open water (dark) starting to open up. If you look very close you can follow the Lena River upstream from the Arctic Ocean all the way to Lake Baikal. Much of the Middle East was clear and you can trace spectacular swirl patterns of folded rock layers through Iran, Afghanistan, and Pakistan. These mountains formed as the Eurasian and Arabian tectonic plates collided.

AP: Arabian Peninsula; CS: Caspian Sea; H: Himalayan Mountains; L: Lena River; I: Indian Ocean; A: Australia; J: Japan; P: Pacific Ocean; large yellow arrow indicates approximate position of the North Pole. Credit: NASA/Goddard/Arizona State University

Browse the full-sized image at the LRO Camera website maintained by Arizona State University.

For more information visit http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/lroc-20100624-earth.html

'L2' Will be the James Webb Space Telescope's Home in Space

When you ask an astronomer about the James Webb Space Telescope's orbit, they'll tell you something that sounds like it came from a science-fiction novel. The Webb won't be orbiting the Earth –instead we will send it almost a million miles out into space to a place called "L2."

L2 is short-hand for the second Lagrange Point, a wonderful accident of gravity and orbital mechanics, and the perfect place to park the Webb telescope in space. There are five so-called "Lagrange Points" - areas where gravity from the sun and Earth balance the orbital motion of a satellite. Putting a spacecraft at any of these points allows it to stay in a fixed position relative to the Earth and sun with a minimal amount of energy needed for course correction.

The five Lagrangian points for the Sun-Earth system are shown in the diagram below. An object placed at any one of these 5 points will stay in place relative to the other two. Credit: NASA

The term L2 may sound futuristic and mysterious, but the name actually honors a Mathematician born in 1736. The Lagrange points were named after the Italian-born mathematician and astronomer Joseph-Louis Lagrange, who made important contributions to classical and celestial mechanics. Lagrange studied the "three-body problem" (so-called because three bodies are orbiting each other) for the Earth, sun, and moon in 1764, and by 1772 he had found the solution; there are five stable points at which you could put an object and have it stay fixed in place relative to the other two.

In the case of L2, this happens about 930,000 miles away from the Earth in the exact opposite direction from the sun. The Earth, as we know, orbits the sun once every year. Normally, an object almost a million miles farther out from the sun should move more slowly, taking more than a year to complete its orbit around the sun. However, at L2, exactly lined up with both the sun and Earth, the added gravity of the two large bodies pulling in the same direction gives a spacecraft an extra boost of energy, locking it into perfect unison with the Earth's yearly orbit. The Webb telescope will be placed slightly off the true balance point, in a gentle orbit around L2.

Why send the Webb telescope all the way out to L2? When astronomers began to think about where the Webb telescope should be placed in space, there were several considerations to keep in mind. To begin with, the Webb telescope will view the universe entirely in infrared light, what we commonly think of as heat radiation. To give the telescope the best chance of detecting distant, dim objects in space, the coldest temperatures possible are needed.

The James Webb Space Telescope (identified as "JWST" here) relative to the Hubble telescope's orbit around the Earth. Credit: NASA

"A huge advantage of deep space (like L2) when compared to Earth orbit is that we can radiate the heat away," said Jonathan P. Gardner, the Deputy Senior Project Scientist on the Webb Telescope mission and Chief of the Observational Cosmology Laboratory at NASA's Goddard Space Flight Center in Greenbelt, Md. "Webb works in the infrared, which is heat radiation. To see the infrared light from distant stars and galaxies, the telescope has to be cold. Webb's large sunshield will protect it from both Sunlight and Earthlight, allowing it to cool to 225 degrees below zero Celsius (minus 370 Fahrenheit)." For the sunshield to be effective, Webb will need to be an orbit where the sun and Earth are in about the same direction.

With the sun and the Earth in the same part of the sky, the Webb telescope will enjoy an open, unimpeded view of the universe. In comparison, the Hubble Space Telescope is in low-Earth orbit where it goes in and out of the Earth's shadow every 90 minutes. Hubble's view is blocked by the Earth for part of each orbit, limiting where the telescope can look at any given time.

The Spitzer Space Telescope, another infrared telescope, is in orbit around the sun and drifting away from the Earth. Spitzer is already more than 100 million kilometers (60 million miles) away from the Earth, and eventually its path will take it to the other side of the sun. Once we can no longer communicate with Spitzer that means it is at the end of its mission life.

This animation shows the Webb Telescope spacecraft orbiting far from the Earth. Credit: NASA/Chris Meaney (HTSI)

In contrast, a major perk of parking at L2 is the ease of communications. Essentially, the Webb telescope will always be at the same point in space. "We can have continuous communications with Webb through the Deep Space Network (DSN)," Gardner said. "During routine operations, we will uplink command sequences and downlink data up to twice per day, through the DSN. The observatory can perform a sequence of commands (pointing and observations) autonomously. Typically, we will upload a full week's worth of commands at a time, and make updates daily as needed."

Even before the Webb telescope, L2 has been known to astronomers as a good spot for space-based observatories. There are already several satellites in the L2 orbit, including the Wilkinson Microwave Anisotropy Probe, and the Herschel and Planck space observatories. But there's plenty of room for another neighbor, and the Webb telescope will be heading out to L2 in the near future.

The Webb telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency.

For more information visit http://www.nasa.gov/topics/universe/features/webb-l2.html

Why NASA Keeps a Close Eye on the Sun's Irradiance

For more than two centuries, scientists have wondered how much heat and light the sun expels, and whether this energy varies enough to change Earth’s climate. In the absence of a good method for measuring the sun's output, the scientific conversation was often heavy with speculation.

By 1976, that began to change when Jack Eddy, a solar astronomer from Boulder, Colo., examined historical records of sunspots and published a seminal paper that showed some century-long variations in solar activity are connected with major climatic shifts. Eddy helped show that an extended lull in solar activity during the 17th Century --called the Maunder Minimum -- was likely connected to a decades-long cold period on Earth called the "Little Ice Age."

Two years after Eddy published his paper, NASA launched the first in a series of satellite instruments called radiometers, which measure the amount of sunlight striking the top of Earth's atmosphere, or total solar irradiance. Radiometers have provided unparalleled details about how the sun's irradiance has varied in the decades since. Such measurements have helped validate and expand upon Eddy's findings. And they've led to a number of other discoveries—and questions—about the sun.

Sunspots are darker areas of the Sun that have lower solar irradiance than other areas. A large sunspot group in 2003, observed by the Total Irradiance Monitor (TIM) radiometer, caused irradiance to decrease by 0.34 percent. Credit: University of Colorado/Laboratory for Atmospheric and Space Physics/Greg Kopp

Without radiometers, scientists would probably still wonder how much energy the sun emits and whether it varies with the sunspot cycle. They wouldn't know of the competition between dark sunspots and bright spots called faculae that drives irradiance variations.

And they’d have little chance of answering a question that continues to perplex solar experts today: Has overall irradiance changed progressively throughout the past three 11-year cycles, or are variations in the sun's irradiance limited to a single cycle?

The answer has important implications for understanding climate change, as some scientists have suggested that trends in solar irradiance account for a significant portion of global warming.

The next space radiometer, slated for launch this November aboard NASA's Glory satellite, should help chip away at the uncertainty that surrounding the sun's role in climate change.

A Variable Sun It's well known today that the sun's irradiance fluctuates constantly in conjunction with sunspots, which become more and less abundant every 11 years due to turbulent magnetic fields that course through the sun's interior and erupt onto its surface.

But as recently as the 1970s, scientists assumed that the sun’s irradiance was unchanging; the amount of energy it expels was even called the "solar constant."

It was data from radiometers aboard Nimbus 7, launched in 1978, and the Solar Maximum Mission, launched two years later, that were the death knell to the solar constant. Soon after launching, instruments aboard both satellites showed that solar irradiance changed significantly as patches of sunspots rotated around the sun's surface. Irradiance would fall, for example, when groups of sunspots faced Earth. And it would recover when the sunspots rotated to the far side of the sun.

Likewise, in 2003, a radiometer aboard NASA's Solar Radiation and Climate Experiment (SORCE) satellite observed large sunspot patches that caused irradiance to drop by as much 0.34 percent, the largest short-term decrease ever recorded.

"When you look at longer scales on the sun, it's the opposite," said Lean, a solar scientist at the U.S. Naval Research Laboratory in Washington, D.C., and a member of Glory's science team. "Overall, irradiance actually increases when the sun is more active even though sunspots are more common."

Although sunspots cause a decrease in irradiance they're accompanied by bright white blotches called faculae that cause an overall increase in solar irradiance. Credit: NASA/Goddard/SORCE

How can increases in dark, cool sunspots yield increases in irradiance? "It didn't make much sense until we were able to show that sunspots are just half of the story," said Lean.

Measurements collected during the 1980s and 1990s gave scientists the evidence they needed to prove that irradiance is actually a balance between darkening from sunspots and brightening from accompanying hot regions called faculae, a word meaning "bright torch" in Latin.

When solar activity increases, as it does every 11 years or so, both sunspots and faculae become more numerous. But during the peak of a cycle, the faculae brighten the sun more than sunspots dim it.

Overall, radiometers show that the sun’s irradiance changes by about 0.1 percent as the number of sunspots varies from about 20 sunspots or less per year during periods of low activity (solar minimum) to between 100 and 150 during periods of high activity (solar maximum).

“That may seem like a tiny amount, but it’s critical we understand even these small changes if we want to understand whether the sun's output is trending up or down and affecting climate,” said Greg Kopp, a principal investigator for Glory and scientist at the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

Like sunspots, solar prominences are more likely to occur during the most active part of the solar cycle. Yet despite their striking appearance, they have little impact on the sun's total solar irradiance. Credit: NASA/GSFC/Solar Dynamics Observatory's AIA Instrument

Though most scientists believe the 0.1 percent variation is too subtle to explain all of the recent warming, it's not impossible that long-term patterns -- proceeding over hundreds or thousands of years -- could cause more severe swings that could have profound impacts on climate.

Searching for a Trend Line A total of 10 radiometers have monitored the sun since Nimbus 7, and by patching all of the measurements together into one data stream, scientists have tried to identify whether the sun’s irradiance has increased or decreased over the last three cycles.

However, melding the results from different instruments has proven complicated because many of the radiometers record slightly different absolute measurements. And the areas of overlap between instruments in the long-term record aren't as robust as scientists would like.

As a result, questions remain about how the sun's irradiance has changed. Richard Willson, principal investigator for NASA's Active Cavity Radiometer Irradiance Monitor (ACRIM), reported in a 2003 paper that the overall brightness of the sun was increasing by 0.05 percent per decade.

Subsequent assessments of the same data have come to a different conclusion. Other groups of scientists have shown that the apparent upward trend is actually an artifact of the radiometers and how they degrade in orbit. Complicating the issue further, an instrument aboard NASA's Solar and Heliospheric Observatory (SOHO) measured irradiance levels during a solar minimum in 2008 that were actually lower than the previous solar minimum.

Which measurements are right? Has the sun experienced subtle brightening or dimming during the last few solar cycles? Such questions remain controversial, but the radiometer aboard Glory, called the Total Irradiance Monitor (TIM), is ready to provide answers. The Glory TIM will be more accurate and stable than previous instruments because of unique optical and electrical advances. And each of its components has undergone a rigorous regime of calibrations at a newly-built facility at the University of Colorado.

“It’s a very exciting time to be studying the sun,” said Lean. “Every day there's something new, and we’re on the verge of answering some very important questions.”

Related Links:
Changing Sun, Changing Climate
www.aip.org/history/climate/solar.htm

New Sun Watching Instrument to monitor Sunlight Fluctuations
www.nasa.gov/topics/earth/features/glory_irradiance.html

Glory Website
www.nasa.gov/mission_pages/Glory/main/index.html

LASP Total Irradiance Monitor Website
lasp.colorado.edu/sorce/instruments/tim.htm

GISS Total Irradiance Monitor Page
glory.giss.nasa.gov/tim/

SORCE Website
lasp.colorado.edu/sorce/index.htm

SORCE Earth Observatory Factsheet
earthobservatory.nasa.gov/Features/SORCE/sorce_07.php

For more information visit http://www.nasa.gov/topics/solarsystem/features/sun-brightness.html

Final Attempts to Hear from Mars Phoenix Scheduled

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

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

Artist concept of NASA's Mars Odyssey orbiter. Image credit: NASA/JPL

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

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

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

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

For more information visit http://www.nasa.gov/mission_pages/phoenix/news/phx20100513.html

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Engineers Diagnosing Voyager 2 Data System

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

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

This artist's rendering depicts NASAs Voyager 2 spacecraft as it studies the outer limits of the heliosphere - a magnetic 'bubble' around the solar system that is created by the solar wind. Image credit: NASA/JPL-Caltech.

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

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

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

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

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

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

For more information about the Voyagers, visit: http://voyager.jpl.nasa.gov/.

For more information visit http://www.nasa.gov/mission_pages/voyager/voyager20100506.html

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NASA Satellite Imagery Keeping Eye on the Gulf Oil Spill

NASA's Terra satellite flew over the Deepwater Horizon rig's oil spill in the Gulf of Mexico on Saturday, May 1 and captured a natural-color image of the slick from space. The oil slick resulted from an accident at the Deepwater Horizon rig in the Gulf of Mexico.

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA’s Terra satellite captured a natural-color image. The oil slick appeared as a tangle of dull gray on the ocean surface, made visible to the satellite sensor by the sun’s reflection on the ocean surface. On May 1, most of the oil slick was southeast of the Mississippi Delta.

The Deepwater Horizon oil spill (appearing as a dull gray color) is southeast of the Mississippi Delta in this May 1, 2010, image from NASA's MODIS instrument. Credit: NASA/Goddard/MODIS Rapid Response Team

The National Oceanic and Atmospheric Administration (NOAA) is the lead agency on oil spills and uses airplane fly-over's to assess oil spill extent. NASA's Terra and Aqua satellites are also helping NOAA with satellite images of the area.

On Sunday, May 2, NOAA restricted fishing in federal waters of the Gulf of Mexico from the mouth of the Mississippi to Pensacola Bay for at least ten days. More details about the closure can be found at: http://sero.nmfs.noaa.gov/. In addition to the federal closure, Louisiana closed vulnerable fisheries in state waters -- within three miles of the coast. NOAA noted that anyone wanting to report oil on land, or for general Community and Volunteer Information, please call 1-866-448-5816. To report oiled or injured wildlife, please call 1-800-557-1401.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center, Greenbelt, Md.

For more information visit http://www.nasa.gov/topics/earth/features/oil-creep.html

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Scientists Say Ice Lurks in Asteroid's Cold Heart

Scientists using a NASA funded telescope have detected water-ice and carbon-based organic compounds on the surface of an asteroid. The cold hard facts of the discovery of the frosty mixture on one of the asteroid belt's largest occupants, suggests that some asteroids, along with their celestial brethren, comets, were the water carriers for a primordial Earth. The research is published in today's issue of the journal Nature.

"For a long time the thinking was that you couldn't find a cup's worth of water in the entire asteroid belt," said Don Yeomans, manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "Today we know you not only could quench your thirst, but you just might be able to fill up every pool on Earth – and then some."

In this artist's concept, a narrow asteroid belt filled with rocks and dusty debris orbits a star similar to our own sun. Image credit: NASA/JPL-Caltech

The discovery is a result of six years of observing asteroid 24 Themis by astronomer Andrew Rivkin of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. Rivkin, along with Joshua Emery, of the University of Tennessee in Knoxville, employed the NASA Infrared Telescope Facility to take measurements of the asteroid on seven separate occasions beginning in 2002. Buried in their compiled data was the consistent infrared signature of water ice and carbon-based organic materials.

The study's findings are particularly surprising because it was believed that Themis, orbiting the sun at "only" 479 million kilometers (297 million miles), was too close to the solar system's fiery heat source to carry water ice left over from the solar system's origin 4.6 billion years ago.

Now, the astronomical community knows better. The research could help re-write the book on the solar system's formation and the nature of asteroids.

"This is exciting because it provides us a better understanding about our past – and our possible future," said Yeomans. "This research indicates that not only could asteroids be possible sources of raw materials, but they could be the fueling stations and watering holes for future interplanetary exploration."

Rivkin and Emory's findings were independently confirmed by a team led by Humberto Campins at the University of Central Florida in Orlando.

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

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. More information about asteroids and near-Earth objects is at: http://www.jpl.nasa.gov/asteroidwatch .

For more information visit http://www.nasa.gov/topics/solarsystem/features/asteroid20100428.html

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Solar Flare Activity For First Light

Images taken by SDO immediately after the AIA CCD cameras cooled on March 30, 2010. This image shows several flares and their associated waves across the Sun. Credit: NASA/GSFC/AIA

For more information visit http://www.nasa.gov/mission_pages/sdo/multimedia/gallery/f_211_193_171.jpg.html

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NASA's New Eye on the Sun Delivers Stunning First Images

NASA's recently launched Solar Dynamics Observatory, or SDO, is returning early images that confirm an unprecedented new capability for scientists to better understand our sun’s dynamic processes. These solar activities affect everything on Earth.

Some of the images from the spacecraft show never-before-seen detail of material streaming outward and away from sunspots. Others show extreme close-ups of activity on the sun’s surface. The spacecraft also has made the first high-resolution measurements of solar flares in a broad range of extreme ultraviolet wavelengths.

"These initial images show a dynamic sun that I had never seen in more than 40 years of solar research,” said Richard Fisher, director of the Heliophysics Division at NASA Headquarters in Washington. "SDO will change our understanding of the sun and its processes, which affect our lives and society. This mission will have a huge impact on science, similar to the impact of the Hubble Space Telescope on modern astrophysics.”

A full-disk multiwavelength extreme ultraviolet image of the sun taken by SDO on March 30, 2010. False colors trace different gas temperatures. Reds are relatively cool (about 60,000 Kelvin, or 107,540 F); blues and greens are hotter (greater than 1 million Kelvin, or 1,799,540 F). Credit: NASA

Launched on Feb. 11, 2010, SDO is the most advanced spacecraft ever designed to study the sun. During its five-year mission, it will examine the sun's magnetic field and also provide a better understanding of the role the sun plays in Earth's atmospheric chemistry and climate. Since launch, engineers have been conducting testing and verification of the spacecraft’s components. Now fully operational, SDO will provide images with clarity 10 times better than high-definition television and will return more comprehensive science data faster than any other solar observing spacecraft.

A movie of the March 30, 2010, solar prominence eruption, as seen by SDO. Credit: NASA/Goddard

SDO will determine how the sun's magnetic field is generated, structured and converted into violent solar events such as turbulent solar wind, solar flares and coronal mass ejections. These immense clouds of material, when directed toward Earth, can cause large magnetic storms in our planet’s magnetosphere and upper atmosphere.

SDO will provide critical data that will improve the ability to predict these space weather events. NASA's Goddard Space Flight Center in Greenbelt, Md., built, operates and manages the SDO spacecraft for the agency’s Science Mission Directorate in Washington.

“I’m so proud of our brilliant work force at Goddard, which is rewriting science textbooks once again.” said Sen. Barbara Mikulski, D-Md., chairwoman of the Commerce, Justice and Science Appropriations Subcommittee that funds NASA. “This time Goddard is shedding new light on our closest star, the sun, discovering new information about powerful solar flares that affect us here on Earth by damaging communication satellites and temporarily knocking out power grids. Better data means more accurate solar storm warnings.”

This image compares the relative size of SDO's imagery to that of other missions. Credit: NASA

Space weather has been recognized as a cause of technological problems since the invention of the telegraph in the 19th century. These events produce disturbances in electromagnetic fields on Earth that can induce extreme currents in wires, disrupting power lines and causing widespread blackouts. These solar storms can interfere with communications between ground controllers, satellites and airplane pilots flying near Earth's poles. Radio noise from the storm also can disrupt cell phone service.

More "Hello, SDO!" videos from NASA Goddard's Scientific Visualization Studio. Credit: NASA/Goddard/Chris Smith

SDO will send 1.5 terabytes of data back to Earth each day, which is equivalent to a daily download of half a million songs onto an MP3 player. The observatory carries three state-of the-art instruments for conducting solar research.

The Helioseismic and Magnetic Imager maps solar magnetic fields and looks beneath the sun’s opaque surface. The experiment will decipher the physics of the sun’s activity, taking pictures in several very narrow bands of visible light. Scientists will be able to make ultrasound images of the sun and study active regions in a way similar to watching sand shift in a desert dune. The instrument’s principal investigator is Phil Scherrer of Stanford University. HMI was built by a collaboration of Stanford University and the Lockheed Martin Solar and Astrophysics Laboratory in Palo Alto, Calif.

The Atmospheric Imaging Assembly is a group of four telescopes designed to photograph the sun’s surface and atmosphere. The instrument covers 10 different wavelength bands, or colors, selected to reveal key aspects of solar activity. These types of images will show details never seen before by scientists. The principal investigator is Alan Title of the Lockheed Martin Solar and Astrophysics Laboratory, which built the instrument.

The Extreme Ultraviolet Variability Experiment measures fluctuations in the sun’s radiant emissions. These emissions have a direct and powerful effect on Earth’s upper atmosphere -- heating it, puffing it up, and breaking apart atoms and molecules. Researchers don't know how fast the sun can vary at many of these wavelengths, so they expect to make discoveries about flare events. The principal investigator is Tom Woods of the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. LASP built the instrument.

"These amazing images, which show our dynamic sun in a new level of detail, are only the beginning of SDO's contribution to our understanding of the sun," said SDO Project Scientist Dean Pesnell of Goddard.

SDO is the first mission of NASA's Living with a Star Program, or LWS, and the crown jewel in a fleet of NASA missions that study our sun and space environment. The goal of LWS is to develop the scientific understanding necessary to address those aspects of the connected sun-Earth system that directly affect our lives and society.

For more information visit http://www.nasa.gov/mission_pages/sdo/news/first-light.html

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Lunar Polar Craters May Be Electrified

As the solar wind flows over natural obstructions on the moon, it may charge polar lunar craters to hundreds of volts, according to new calculations by NASA’s Lunar Science Institute team.

Polar lunar craters are of interest because of resources, including water ice, which exist there. The moon’s orientation to the sun keeps the bottoms of polar craters in permanent shadow, allowing temperatures there to plunge below minus 400 degrees Fahrenheit, cold enough to store volatile material like water for billions of years. "However, our research suggests that, in addition to the wicked cold, explorers and robots at the bottoms of polar lunar craters may have to contend with a complex electrical environment as well, which can affect surface chemistry, static discharge, and dust cling," said William Farrell of NASA’s Goddard Space Flight Center, Greenbelt, Md. Farrell is lead author of a paper on this research published March 24 in the Journal of Geophysical Research. The research is part of the Lunar Science Institute’s Dynamic Response of the Environment at the moon (DREAM) project.

"This important work by Dr. Farrell and his team is further evidence that our view on the moon has changed dramatically in recent years," said Gregory Schmidt, deputy director of the NASA Lunar Science Institute at NASA's Ames Research Center, Moffett Field, Calif. "It has a dynamic and fascinating environment that we are only beginning to understand."

Solar wind inflow into craters can erode the surface, which affects recently discovered water molecules. Static discharge could short out sensitive equipment, while the sticky and extremely abrasive lunar dust could wear out spacesuits and may be hazardous if tracked inside spacecraft and inhaled over long periods.

New research from NASA's Lunar Science Institute indicates that the solar wind may be charging certain regions at the lunar poles to hundreds of volts. In this short video Dr. Bill Farrell discusses this research and what it means for future exploration of the moon's poles. Credit: NASA/Goddard Space Flight Center

The solar wind is a thin gas of electrically charged components of atoms -- negatively charged electrons and positively charged ions -- that is constantly blowing from the surface of the sun into space. Since the moon is only slightly tilted compared to the sun, the solar wind flows almost horizontally over the lunar surface at the poles and along the region where day transitions to night, called the terminator.

The researchers created computer simulations to discover what happens when the solar wind flows over the rims of polar craters. They discovered that in some ways, the solar wind behaves like wind on Earth -- flowing into deep polar valleys and crater floors. Unlike wind on Earth, the dual electron-ion composition of the solar wind may create an unusual electric charge on the side of the mountain or crater wall; that is, on the inside of the rim directly below the solar wind flow.

Since electrons are over 1,000 times lighter than ions, the lighter electrons in the solar wind rush into a lunar crater or valley ahead of the heavy ions, creating a negatively charged region inside the crater. The ions eventually catch up, but rain into the crater at consistently lower concentrations than that of the electrons. This imbalance in the crater makes the inside walls and floor acquire a negative electric charge. The calculations reveal that the electron/ion separation effect is most extreme on a crater's leeward edge – along the inside crater wall and at the crater floor nearest the solar wind flow. Along this inner edge, the heavy ions have the greatest difficulty getting to the surface. Compared to the electrons, they act like a tractor-trailer struggling to follow a motorcycle; they just can’t make as sharp a turn over the mountain top as the electrons. "The electrons build up an electron cloud on this leeward edge of the crater wall and floor, which can create an unusually large negative charge of a few hundred Volts relative to the dense solar wind flowing over the top," says Farrell.

The negative charge along this leeward edge won’t build up indefinitely. Eventually, the attraction between the negatively charged region and positive ions in the solar wind will cause some other unusual electric current to flow. The team believes one possible source for this current could be negatively charged dust that is repelled by the negatively charged surface, gets levitated and flows away from this highly charged region. "The Apollo astronauts in the orbiting Command Module saw faint rays on the lunar horizon during sunrise that might have been scattered light from electrically lofted dust," said Farrell. "Additionally, the Apollo 17 mission landed at a site similar to a crater environment – the Taurus-Littrow valley. The Lunar Ejecta and Meteorite Experiment left by the Apollo 17 astronauts detected impacts from dust at terminator crossings where the solar wind is nearly-horizontal flowing, similar to the situation over polar craters."

Next steps for the team include more complex computer models. "We want to develop a fully three-dimensional model to examine the effects of solar wind expansion around the edges of a mountain. We now examine the vertical expansion, but we want to also know what happens horizontally," said Farrell. As early as 2012, NASA will launch the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission that will orbit the moon and could look for the dust flows predicted by the team’s research.

This work was enabled by support from NASA Goddard’s Internal Research and Development program and NASA’s Lunar Science Institute. The team includes researchers from NASA Goddard, the University of California, Berkeley, and the University of Maryland, Baltimore County.

For more information visit http://www.nasa.gov/topics/moonmars/features/electric-craters.html