SpaceX Test Fires Engine Prototype for Astronaut Escape System

One of NASA's industry partners, Space Exploration Technologies (SpaceX), completed a full-duration, full-thrust firing of its new SuperDraco engine prototype at the company’s Rocket Development Facility in McGregor, Texas. The firing was in preparation for the ninth milestone to be completed under SpaceX's funded Space Act Agreement (SAA) with NASA's Commercial Crew Program (CCP).

“We are happy that our investment in SpaceX was met with success in the firing of its new engine.” Nine months after CCP awarded SpaceX $75 million to design and test its Dragon spacecraft with a launch abort system, the company test fired its SuperDraco development engine to demonstrate its capabilities of keeping an astronaut crew safe during launch and ascent. The engine produced full thrust within approximately 100 milliseconds of the ignition command. It also fired for 5 seconds, which is the same amount of time the engines would burn during an emergency abort.

"Eight SuperDracos will be built into the sidewalls of the Dragon spacecraft, producing up to 120,000 pounds of axial thrust to quickly carry astronauts to safety should an emergency occur during launch," said Elon Musk, SpaceX chief executive officer and chief technology officer. "Those engines will have the ability to deep throttle, providing astronauts with precise control and enormous power."

SuperDracos are powered by the same propellant that powers the 18 Draco thrusters Dragon will use to maneuver in orbit and during re-entry. To achieve the power necessary to quickly carry the spacecraft out of harm’s way, SuperDraco engines would burn through propellant 200 times faster than the engines Dragon uses for orbital maneuvers. "With eight SuperDracos, if any one engine fails the abort still can be carried out successfully."

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IBEX: Glimpses of the Interstellar Material Beyond our Solar System

A great magnetic bubble surrounds the solar system as it cruises through the galaxy. The sun pumps the inside of the bubble full of solar particles that stream out to the edge until they collide with the material that fills the rest of the galaxy, at a complex boundary called the heliosheath. On the other side of the boundary, electrically charged particles from the galactic wind blow by, but rebound off the heliosheath, never to enter the solar system. Neutral particles, on the other hand, are a different story. They saunter across the boundary as if it weren't there, continuing on another 7.5 billion miles for 30 years until they get caught by the sun's gravity, and sling shot around the star.



There, NASA's Interstellar Boundary Explorer lies in wait for them. Known as IBEX for short, this spacecraft methodically measures these samples of the mysterious neighborhood beyond our home. IBEX scans the entire sky once a year, and every February, its instruments point in the correct direction to intercept incoming neutral atoms. IBEX counted those atoms in 2009 and 2010 and has now captured the best and most complete glimpse of the material that lies so far outside our own system.

The results? It's an alien environment out there: the material in that galactic wind doesn't look like the same stuff our solar system is made of.
"We've directly measured four separate types of atoms from interstellar space and the composition just doesn't match up with what we see in the solar system," says Eric Christian, mission scientist for IBEX at NASA's Goddard Space Flight Center in Greenbelt, Md. "IBEX's observations shed a whole new light on the mysterious zone where the solar system ends and interstellar space begins."

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Mars-Bound Instrument Detects Solar Burst's Effects

The largest solar particle event since 2005 has been detected by the radiation-monitoring instrument aboard the Mars Science Laboratory spacecraft, on its way from Earth to Mars.

The Radiation Assessment Detector, inside the mission's Curiosity rover tucked inside the spacecraft, is measuring the radiation exposure that could affect a human astronaut on a potential Mars mission. It has measured an increase resulting from a Jan. 22 solar storm observed by other NASA spacecraft. No harmful effects to the Mars Science Laboratory have been detected from this solar event.

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Space Shuttle Program: Spanning 30 Years of Discovery

NASA's space shuttle fleet began setting records with its first launch on April 12, 1981 and continued to set high marks of achievement and endurance through 30 years of missions. Starting with Columbia and continuing with Challenger, Discovery, Atlantis and Endeavour, the spacecraft has carried people into orbit repeatedly, launched, recovered and repaired satellites, conducted cutting-edge research and built the largest structure in space, the International Space Station. The final space shuttle mission, STS-135, ended July 21, 2011 when Atlantis rolled to a stop at its home port, NASA's Kennedy Space Center in Florida.

As humanity's first reusable spacecraft, the space shuttle pushed the bounds of discovery ever farther, requiring not only advanced technologies but the tremendous effort of a vast workforce. Thousands of civil servants and contractors throughout NASA's field centers and across the nation have demonstrated an unwavering commitment to mission success and the greater goal of space exploration.

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Heliophysics

We live in the extended atmosphere of an active star. While sunlight enables and sustains life, the Sun's variability produces streams of high energy particles and radiation that can harm life or alter its evolution. Under the protective shield of a magnetic field and atmosphere, the Earth is an island in the Universe where life has developed and flourished. The origins and fate of life on Earth are intimately connected to the way the Earth responds to the Sun's variations.

Understanding the Sun, Heliosphere, and Planetary Environments as a single connected system is the goal of the Science Mission Directorate's Heliophysics Research Program. In addition to solar processes, our domain of study includes the interaction of solar plasma and radiation with Earth, the other planets, and the Galaxy. By analyzing the connections between the Sun, solar wind, planetary space environments, and our place in the Galaxy, we are uncovering the fundamental physical processes that occur throughout the Universe. Understanding the connections between the Sun and its planets will allow us to predict the impacts of solar variability on humans, technological systems, and even the presence of life itself.

We have already discovered ways to peer into the internal workings of the Sun and understand how the Earth's magnetosphere responds to solar activity. Our challenge now is to explore the full system of complex interactions that characterize the relationship of the Sun with the solar system. Understanding these connections is especially critical as we contemplate our destiny in the third millennium. Heliophysics is needed to facilitate the accelerated expansion of human experience beyond the confines of our Earthly home. Recent advances in technology allow us, for the first time, to realistically contemplate voyages beyond the solar system.

There are three primary objectives that define the multi-decadal studies needed:

To understand the changing flow of energy and matter throughout the Sun, Heliosphere, and Planetary Environments.
To explore the fundamental physical processes of space plasma systems.
To define the origins and societal impacts of variability in the Earth-Sun System.

A combination of interrelated elements is used to achieve these objectives. They include complementary missions of various sizes; timely development of enabling and enhancing technologies; and acquisition of knowledge through research, analysis, theory, and modeling.

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Crew Prepares for Progress 46 Arrival

To prepare for the impending arrival of the ISS Progress 46 cargo craft to the International Space Station, Expedition 30 Flight Engineers Anton Shkaplerov and Oleg Kononenko reviewed procedures for the use of TORU, the Russian telerobotically operated rendezvous system. The crew can use TORU to monitor the docking of a Progress cargo craft with the station or take control of the process if difficulties arise.

At the Baikonur Cosmodrome in Kazakhstan, meanwhile, Progress 46 was hauled to its launch pad by rail and vertically erected for final preparations for launch Wednesday at 6:06 p.m. EST (5:06 a.m. Baikonur time Thursday). Rollout occurred at sunrise at the Baikonur Cosmodrome with temperatures around zero degrees Fahrenheit. The Progress 46 craft is loaded with 2,050 pounds of propellant, 110 pounds of oxygen and air, 926 pounds of water and 2,778 pounds of spare parts and experiment hardware for a total of 2.9 tons of food, fuel and equipment to be delivered to the six crew members on the orbital laboratory. NASA TV coverage of the launch begins at 5:45 p.m.

Commander Dan Burbank spent a large portion of his day collecting fluid samples from the Internal Thermal Control System in the station’s U.S. segment. This sample collection is part of regular station maintenance. He also spoke to students in Placerville, Calif., via amateur radio.



Astronaut Don Pettit, a flight engineer, participated in a session with the Integrated Cardiovascular (ICV) experiment. ICV researches the extent and causes of weakening of the heart during long-duration missions. Additionally, Pettit conducted a safety video tour of the station, which is required once every increment for the benefit of ground controllers.

Kononenko participated in a Russian medical test called SPRUT-2, which investigates the distribution and behavior of human body fluids in zero gravity.
Flight Engineer Anatoly Ivanishin worked with the radiation payload suite Matryoshka-R. The Russian payload is designed for sophisticated radiation studies and is named after the traditional Russian set of nested dolls.

Andre Kuipers, also a flight engineer, set up and tested the Urine Monitoring System. He also initiated charging of batteries some of the Russian crew members will use for pistol grip tools during a spacewalk slated for Feb. 16. The spacewalkers will attach five debris shields to the Zvezda service module and move one of the two Strela booms from Pirs to the Poisk module.

At Mission Control, the robotics officers maneuvered the Canadarm2 in a viewing position to inspect the Common Berthing Mechanism on Harmony’s Earth-facing port, to which the SpaceX Dragon spacecraft will be berthed when it reaches the complex.

Ground controllers had been following reports earlier in the week from U.S. Space Command that a piece of Chinese satellite debris about 4 inches (10 centimeters) in diameter might come close enough to the station to warrant moving out of the way, what is called a debris avoidance maneuver. Planning for the move was called off when tracking showed the highly erratic debris was not a concern.

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Herschel and Spitzer See Nearby Galaxies' Stardust

The cold dust that builds blazing stars is revealed in new images that combine observations from the Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions; and NASA's Spitzer Space Telescope. The new images map the dust in the galaxies known as the Large and Small Magellanic Clouds, two of the closest neighbors to our own Milky Way galaxy.

The Large Magellanic Cloud looks like a fiery, circular explosion in the combined Herschel-Spitzer infrared data. Ribbons of dust ripple through the galaxy, with significant fields of star formation noticeable in the center, center-left and top right (the brightest center-left region is called 30 Doradus, or the Tarantula Nebula, for its appearance in visible light). The Small Magellanic Cloud has a much more irregular shape. A stream of dust extends to the left in this image, known as the galaxy's "wing," and a bar of star formation appears on the right.

The colors in these images indicate temperatures in the dust that permeate the Magellanic Clouds. Colder regions show where star formation is at its earliest stages or is shut off, while warm expanses point to new stars heating dust surrounding them. The coolest areas and objects appear in red, corresponding to infrared light taken up by Herschel's Spectral and Photometric Imaging Receiver at 250 microns, or millionths of a meter. Herschel's Photodetector Array Camera and Spectrometer fills out the mid-temperature bands, shown in green, at 100 and 160 microns. The warmest spots appear in blue, courtesy of 24- and 70-micron data from Spitzer.

"Studying these galaxies offers us the best opportunity to study star formation outside of the Milky Way," said Margaret Meixner, an astronomer at the Space Telescope Science Institute, Baltimore, Md., and principal investigator for the mapping project. "Star formation affects the evolution of galaxies, so we hope understanding the story of these stars will answer questions about galactic life cycles."

The Large and Small Magellanic Clouds are the two biggest satellite galaxies of our home galaxy, the Milky Way, though they are still considered dwarf galaxies compared to the big spiral of the Milky Way. Dwarf galaxies also contain fewer metals, or elements heavier than hydrogen and helium. Such an environment is thought to slow the growth of stars. Star formation in the universe peaked around 10 billion years ago, even though galaxies contained lesser abundances of metallic dust. Previously, astronomers only had a general sense of the rate of star formation in the Magellanic Clouds, but the new images enable them to study the process in more detail.

The results were presented today at the 219th meeting of the American Astronomical Society in Austin, Texas.

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

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech. Caltech manages JPL for NASA.

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Sun Unleashes X6.9 Class Flare

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NASA's Dawn's Spacecraft Views Dark Side of Vesta

Dawn took this image over Vesta's northern hemisphere after the spacecraft completed its first passage over the dark side of the giant asteroid. It is northern hemisphere winter on Vesta now, so its north pole is in deep shadow.

The Dawn science team is working to determine the significance of the distinct features in this image, which include large grooves or ridges extending for great distances around Vesta.

This image was taken by Dawn's framing camera on July 23, from a distance of 3,200 miles (5,200 kilometers).

The Dawn mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, for NASA. The University of California, Los Angeles, is responsible for overall Dawn mission science. The Dawn framing cameras have been developed and built under the leadership of the Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, with significant contributions by DLR German Aerospace Center, Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig. The Framing Camera project is funded by the Max Planck Society, DLR, and NASA/JPL.

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NASA's Jupiter-Bound Juno Spacecraft Mated to its Rocket

NASA's Juno spacecraft completed its last significant terrestrial journey today, July 27, with a 15-mile (25-kilometer) trip from Astrotech Space Operations in Titusville, Fla., to its launch pad at the Cape Canaveral Air Force Station. The solar-powered, Jupiter-bound spacecraft was secured into place on top of its rocket at 10:42 a.m. EDT (7:42 a.m. PDT).

Juno will arrive at Jupiter in July 2016 and orbit its poles 33 times to learn more about the gas giant's interior, atmosphere and aurora.

"We're about to start our journey to Jupiter to unlock the secrets of the early solar system," said Scott Bolton, the mission's principal investigator from the Southwest Research Institute in San Antonio. "After eight years of development, the spacecraft is ready for its important mission."

Now that the Juno payload is atop the most powerful Atlas rocket ever made -- the United Launch Alliance Atlas V 551 -- a final flurry of checks and tests can begin and confirm that all is go for launch. The final series of checks begins Wednesday with an on-pad functional test. The test is designed to confirm that the spacecraft is healthy after the fueling, encapsulation and transport operations.

"The on-pad functional test is the first of seven tests and reviews that Juno and its flight team will undergo during the spacecraft's last 10 days on Earth," said Jan Chodas, Juno's project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "There are a number of remaining pre-launch activities that we still need to focus on, but the team is really excited that the final days of preparation, which we've been anticipating for years, are finally here. We are ready to go."

The launch period for Juno opens Aug. 5, 2011, and extends through Aug. 26. For an Aug. 5 liftoff, the launch window opens at 11:34 a.m. EDT (8:34 a.m. PDT) and remains open through 12:43 p.m. EDT (9:43 a.m. PDT).

JPL manages the Juno mission for principal investigator Scott Bolton. The Juno mission is part of the New Frontiers Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems of Denver built the spacecraft. Launch management for the mission is the responsibility of NASA's Launch Services Program at the agency's Kennedy Space Center in Florida. JPL is a division of the California Institute of Technology in Pasadena.

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NASA's Hubble Makes One Millionth Science Observation

NASA's Hubble Space Telescope crossed another milestone in its space odyssey of exploration and discovery. On Monday, July 4, the Earth-orbiting observatory logged its one millionth science observation during a search for water in an exoplanet's atmosphere 1,000 light-years away.

"For 21 years Hubble has been the premier space science observatory, astounding us with deeply beautiful imagery and enabling ground-breaking science across a wide spectrum of astronomical disciplines," said NASA Administrator Charles Bolden. He piloted the space shuttle mission that carried Hubble to orbit. "The fact that Hubble met this milestone while studying a faraway planet is a remarkable reminder of its strength and legacy."

Although Hubble is best known for its stunning imagery of the cosmos, the millionth observation is a spectroscopic measurement, where light is divided into its component colors. These color patterns can reveal the chemical composition of cosmic sources.

Hubble's millionth exposure is of the planet HAT-P-7b, a gas giant planet larger than Jupiter orbiting a star hotter than our sun. HAT-P-7b, also known as Kepler 2b, has been studied by NASA's planet-hunting Kepler observatory after it was discovered by ground-based observations. Hubble now is being used to analyze the chemical composition of the planet’s atmosphere.

"We are looking for the spectral signature of water vapor. This is an extremely precise observation and it will take months of analysis before we have an answer," said Drake Deming of the University of Maryland and NASA's Goddard Space Flight Center in Greenbelt, Md. "Hubble demonstrated it is ideally suited for characterizing the atmospheres of exoplanets, and we are excited to see what this latest targeted world will reveal."

Hubble was launched April 24, 1990, aboard space shuttle's Discovery's STS-31 mission. Its discoveries revolutionized nearly all areas of astronomical research from planetary science to cosmology. The observatory has collected more than 50 terabytes of data to-date.

Hubble's odometer reading includes every observation of astronomical targets since its launch and observations used to calibrate its suite of instruments. Hubble made the millionth observation using its Wide Field Camera 3, a visible and infrared light imager with an on-board spectrometer. It was installed by astronauts during the Hubble Servicing Mission 4 in May 2009.

"The Hubble keeps amazing us with groundbreaking science," said Sen. Barbara A. Mikulski, the chairwoman of the Senate Commerce, Justice, Science and Related Agencies Appropriations Subcommittee that funds NASA. "I championed the mission to repair and renew Hubble not just to get one million science observations, but also to inspire millions of children across the planet to become our next generation of stargazers, scientists, astronauts and engineers."

Hubble is a project of international cooperation between NASA and the European Space Agency. Goddard 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.

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Dawn Nears Start of Year-Long Stay at Giant Asteroid

NASA's Dawn spacecraft is on track to begin the first extended visit to a large asteroid. The mission expects to go into orbit around Vesta on July 16 and begin gathering science data in early August. Vesta resides in the main asteroid belt and is thought to be the source of a large number of meteorites that fall to Earth.

"The spacecraft is right on target," said Robert Mase, Dawn project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We look forward to exploring this unknown world during Dawn's one-year stay in Vesta's orbit."

After traveling nearly four years and 1.7 billion miles (2.7 billion kilometers), Dawn is approximately 96,000 miles (155,000 kilometers) away from Vesta. When Vesta captures Dawn into its orbit on July 16, there will be approximately 9,900 miles (16,000 kilometers) between them. When orbit is achieved, they will be approximately 117 million miles (188 million kilometers) away from Earth.

After Dawn enters Vesta's orbit, engineers will need a few days to determine the exact time of capture. Unlike other missions where a dramatic, nail-biting propulsive burn results in orbit insertion around a planet, Dawn has been using its placid ion propulsion system to subtly shape its path for years to match Vesta's orbit around the sun.

Images from Dawn's framing camera, taken for navigation purposes, show the slow progress toward Vesta. They also show Vesta rotating about 65 degrees in the field of view. The images are about twice as sharp as the best images of Vesta from NASA's Hubble Space Telescope, but the surface details Dawn will obtain are still a mystery.

"Navigation images from Dawn's framing camera have given us intriguing hints of Vesta, but we're looking forward to the heart of Vesta operations, when we begin officially collecting science data," said Christopher Russell, Dawn principal investigator, at UCLA. "We can't wait for Dawn to peel back the layers of time and reveal the early history of our solar system."

Dawn's three instruments are all functioning and appear to be properly calibrated. The visible and infrared mapping spectrometer, for example, has started to obtain images of Vesta that are larger than a few pixels in size. During the initial reconnaissance orbit, at approximately 1,700 miles (2,700 kilometers), the spacecraft will get a broad overview of Vesta with color pictures and data in different wavelengths of reflected light. The spacecraft will move into a high-altitude mapping orbit, about 420 miles (680 kilometers) above the surface to systematically map the parts of Vesta's surface illuminated by the sun; collect stereo images to see topographic highs and lows; acquire higher-resolution data to map rock types at the surface; and learn more about Vesta's thermal properties.

Dawn then will move even closer, to a low-altitude mapping orbit approximately 120 miles (200 kilometers) above the surface. The primary science goals of this orbit are to detect the byproducts of cosmic rays hitting the surface and help scientists determine the many kinds of atoms there, and probe the protoplanet's internal structure. As Dawn spirals away from Vesta, it will pause again at the high-altitude mapping orbit. Because the sun's angle on the surface will have progressed, scientists will be able to see previously hidden terrain while obtaining different views of surface features.

"We've packed our year at Vesta chock-full of science observations to help us unravel the mysteries of Vesta," said Carol Raymond, Dawn's deputy principal investigator at JPL. Vesta is considered a protoplanet, or body that never quite became a full-fledged planet.

Dawn launched in September 2007. Following a year at Vesta, the spacecraft will depart for its second destination, the dwarf planet Ceres, in July 2012. Dawn's mission to Vesta and Ceres is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Ala.

UCLA is responsible for overall Dawn mission science. Orbital Sciences Corp. of Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are part of the mission team. JPL is managed for NASA by the California Institute of Technology in Pasadena

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MESSENGER Provides New Data about Mercury

After nearly three months in orbit about Mercury, MESSENGER's payload is providing a wealth of new information about the planet closest to the Sun, as well as a few surprises.

The spacecraft entered orbit around Mercury on March 18, 2011 UTC, becoming the first spacecraft ever to do so. Tens of thousands of images of major features on the planet — previously seen only at comparatively low resolution — are now available in sharp focus. Measurements of the chemical composition of Mercury's surface are providing important clues to the origin of the planet and its geological history. Maps of the planet's topography and magnetic field are revealing new clues to Mercury's interior dynamical processes. And scientists now know that bursts of energetic particles in Mercury's magnetosphere are a continuing product of the interaction of Mercury's magnetic field with the solar wind.

This week, MESSENGER completed is first perihelion passage from orbit, its first superior solar conjunction from orbit, and its first orbit-correction maneuver. "Those milestones provide important context to the continuing feast of new observations that MESSENGER has been sending home on nearly a daily basis,” offers MESSENGER Principal investigator Sean Solomon of the Carnegie Institution of Washington.

A Surface Revealed in Unprecedented Detail

Among the fascinating features seen in MESSENGER flyby images of Mercury were bright, patchy deposits on some crater floors. Without high-resolution images to obtain a closer look, these features remained a curiosity. New targeted Mercury Dual Imaging System images at up to 10 meters per pixel reveal these patchy deposits to be clusters of rimless, irregular pits varying in size from hundreds of meters to several kilometers. These pits are often surrounded by diffuse halos of higher-reflectance material, and they are found associated with central peaks, peak rings, and rims of craters.

"The etched appearance of these landforms is unlike anything we've seen before on Mercury or the Moon," says Brett Denevi, a staff scientist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., and a member of the MESSENGER imaging team. "We are still debating their origin, but they appear to have a relatively young age and may suggest a more abundant than expected volatile component in Mercury's crust."


Mercury's Surface Composition

The X-ray Spectrometer (XRS) — one of two instruments on MESSENGER designed to measure the abundances of many key elements on Mercury — has made several important discoveries since the orbital mission began. The magnesium/silicon, aluminum/silicon, and calcium/silicon ratios averaged over large areas of the planet's surface show that, unlike the surface of the Moon, Mercury's surface is not dominated by feldspar-rich rocks.

XRS observations have also revealed substantial amounts of sulfur at Mercury's surface, lending support to prior suggestions from ground-based telescopic spectral observations that sulfide minerals are present. This discovery suggests that the original building blocks from which Mercury was assembled may have been less oxidized than those that formed the other terrestrial planets, and it has potentially important implications for understanding the nature of volcanism on Mercury.


Mapping of Mercury's Topography and Magnetic Field

MESSENGER's Mercury Laser Altimeter has been systematically mapping the topography of Mercury's northern hemisphere. After more than two million laser-ranging observations, the planet's large-scale shape and profiles of geological features are both being revealed in high detail. The north polar region of Mercury, for instance, is a broad area of low elevations. The overall range in topographic heights seen to date exceeds 9 kilometers.

Two decades ago, Earth-based radar images showed that around both Mercury's north and south poles are deposits characterized by high radar backscatter. These polar deposits are thought to consist of water ice and perhaps other ices preserved on the cold, permanently shadowed floors of high-latitude impact craters. MESSENGER's altimeter is testing this idea by measuring the floor depths of craters near Mercury's north pole. To date, the depths of craters hosting polar deposits are consistent with the idea that those deposits occupy areas in permanent shadow.

Energetic Particle Events at Mercury

One of the major discoveries made by Mariner 10 during the first of its three flybys of Mercury in 1974 were bursts of energetic particles in Mercury's Earth-like magnetosphere. Four bursts of particles were observed on that flyby, so it was puzzling that no such strong events were detected by MESSENGER during any of its three flybys of the planet in 2008 and 2009. With MESSENGER now in near-polar orbit about Mercury, energetic events are being seen almost like clockwork.

"We are assembling a global overview of the nature and workings of Mercury for the first time,” adds Solomon, "and many of our earlier ideas are being cast aside as new observations lead to new insights. Our primary mission has another three Mercury years to run, and we can expect more surprises as our solar system's innermost planet reveals its long-held secrets."

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STEREO Sees Complete Far Side

The far side unveiled! This is the first complete image of the solar far side, the half of the sun invisible from Earth. Captured on June 1, 2011, the composite image was assembled from NASA's two Solar TErrestrial RElations Observatory (STEREO) spacecraft. STEREO-Ahead's data is shown on the left half of image and STEREO-Behind's data on the right.

The STEREO spacecraft reached opposition (180° separation) on February 6 but part of the sun was inaccessible to their combined view until June 1. This image represents the first day when the entire far side could be seen.

The image is aligned so that solar north is directly up. The seam between the two images is inclined because the plane of Earth’s -- and STEREO's -- orbit, known as the "ecliptic", is inclined with respect to the sun's axis of rotation. The data was collected by STEREO's Extreme Ultraviolet Imagers in the SECCHI instrument suites.

STEREO was built and is operated for NASA by the Applied Physical Laboratory of the Johns Hopkins University; the spacecraft were launched on October 25, 2006 aboard a Delta II. The SECCHI instrument suite is a collaboration led by the Naval Research Laboratory, and the EUVI instruments were built by the Lockheed Martin Solar and Astrophysics Laboratory.

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Landsat 5 Satellite Sees Tornado Track near Sturbridge, Massachusetts

On June 1, 2011, a supercell thunderstorm developed over western Massachusetts. The storm produced an EF3 tornado that cut a 39-mile (63-kilometer) track of destruction across southwest and south-central Massachusetts. Not only did the long-lived tornado remain on the ground for many miles, but it also widened to 0.5 miles (0.8 kilometers).

The Thematic Mapper on the Landsat 5 satellite captured this natural-color image on June 5, 2011. This image shows part of the tornado track, including damage in Sturbridge. According to the Boston Globe, Massachusetts state police reported a tornado on the ground in Sturbridge at 5:22 p.m. The tornado was spotted on the Interstate 84 exit, and cars were overturned.

The Boston Globe reported that the Massachusetts governor declared a state of emergency and ordered National Guard troops to assist with cleanup efforts. Tornadoes on June 1 killed at least four residents of the state, as well as reducing homes, schools, and churches to rubble.

The Landsat Program is a series of Earth-observing satellite missions jointly managed by NASA and the U.S. Geological Survey. Since 1972, Landsat satellites have collected information about Earth from space. This science, known as remote sensing, has matured with the Landsat Program.

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NASA's Hubble Finds Rare 'Blue Straggler' Stars in Milky Way's Hub

NASA's Hubble Space Telescope has found a rare class of oddball stars called blue stragglers in the hub of our Milky Way, the first detected within our galaxy's bulge.

Blue stragglers are so named because they seemingly lag behind in the aging process, appearing younger than the population from which they formed. While they have been detected in many distant star clusters, and among nearby stars, they never have been seen inside the core of our galaxy.

It is not clear how blue stragglers form. A common theory is that they emerge from binary pairs. As the more massive star evolves and expands, the smaller star gains material from its companion. This stirs up hydrogen fuel and causes the growing star to undergo nuclear fusion at a faster rate. It burns hotter and bluer, like a massive young star.

The findings support the idea that the Milky Way's central bulge stopped making stars billions of years ago. It now is home to aging sun-like stars and cooler red dwarfs. Giant blue stars that once lived there have long since exploded as supernovae.

The results have been accepted for publication in an upcoming issue of The Astrophysical Journal. Lead author Will Clarkson of Indiana University in Bloomington, will discuss them today at the American Astronomical Society meeting in Boston.

"Although the Milky Way bulge is by far the closest galaxy bulge, several key aspects of its formation and subsequent evolution remain poorly understood," Clarkson said. "Many details of its star-formation history remain controversial. The extent of the blue straggler population detected provides two new constraints for models of the star-formation history of the bulge."

The discovery followed a seven-day survey in 2006 called the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS). Hubble peered at 180,000 stars in the crowded central bulge of our galaxy, 26,000 light-years away. The survey was intended to find hot Jupiter-class planets that orbit very close to their stars. In doing so, the SWEEPS team also uncovered 42 oddball blue stars with brightness and temperatures typical for stars much younger than ordinary bulge stars.

The observations clearly indicate that if there is a young star population in the bulge, it is very small. It was not detected in the SWEEPS program. Blue stragglers long have been suspected to be living in the bulge, but had not been observed because younger stars in the disk of our galaxy lie along the line-of-sight to the core, confusing and contaminating the view.

Astronomers used Hubble to distinguish the motion of the core population from foreground stars in the Milky Way. Bulge stars orbit the galactic center at a different speed than foreground stars. Plotting their motion required returning to the SWEEPS target region with Hubble two years after the first observations were made. The blue stragglers were identified as moving along with the other stars in the bulge.

"The size of the field of view on the sky is roughly that of the thickness of a human fingernail held at arm's length, and within this region, Hubble sees about a quarter million stars toward the bulge," Clarkson said. "Only the superb image quality and stability of Hubble allowed us to make this measurement in such a crowded field."

From the 42 candidate blue stragglers, the investigators estimate 18 to 37 are likely genuine. The remainder could be a mix of foreground objects and, at most, a small population of genuinely young bulge stars.

"The SWEEPS program was designed to detect transiting planets through small light variations" said Kailash Sahu, the principal investigator of the SWEEPS program. "Therefore the program could easily detect the variability of binary pairs, which was crucial in confirming these are indeed blue stragglers."

Hubble is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., 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 in Washington.

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NASA Concludes Attempts to Contact Mars Rover Spirit

NASA is ending attempts to regain contact with the long-lived Mars Exploration Rover Spirit, which last communicated on March 22, 2010.

A transmission that will end on Wednesday, May 25, will be the last in a series of attempts. Extensive communications activities during the past 10 months also have explored the possibility that Spirit might reawaken as the solar energy available to it increased after a stressful Martian winter without much sunlight. With inadequate energy to run its survival heaters, the rover likely experienced colder internal temperatures last year than in any of its prior six years on Mars. Many critical components and connections would have been susceptible to damage from the cold.

Engineers' assessments in recent months have shown a very low probability for recovering communications with Spirit. Communications assets that have been used by the Spirit mission in the past, including NASA's Deep Space Network of antennas on Earth, plus two NASA Mars orbiters that can relay communications, now are needed to prepare for NASA's Mars Science Laboratory mission. MSL is scheduled to launch later this year.

"We're now transitioning assets to support the November launch of our next generation Mars rover, Curiosity," said Dave Lavery, NASA’s program executive for solar system exploration. "However, while we no longer believe there is a realistic probability of hearing from Spirit, the Deep Space Network may occasionally listen for any faint signals when the schedule permits."

Spirit landed on Mars on Jan. 3, 2004, for a mission designed to last three months. After accomplishing its prime-mission goals, Spirit worked to accomplish additional objectives. Its twin, Opportunity, continues active exploration of Mars.

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Cassini and Telescope See Violent Saturn Storm

NASA's Cassini spacecraft and a European Southern Observatory ground-based telescope tracked the growth of a giant early-spring storm in Saturn's northern hemisphere that is so powerful it stretches around the entire planet. The rare storm has been wreaking havoc for months and shooting plumes of gas high into the planet's atmosphere.

Cassini's radio and plasma wave science instrument first detected the large disturbance, and amateur astronomers tracked its emergence in December 2010. As it rapidly expanded, its core developed into a giant, powerful thunderstorm. The storm produced a 3,000-mile-wide (5,000-kilometer-wide) dark vortex, possibly similar to Jupiter's Great Red Spot, within the turbulent atmosphere.

The dramatic effects of the deep plumes disturbed areas high up in Saturn's usually stable stratosphere, generating regions of warm air that shone like bright "beacons" in the infrared. Details are published in this week's edition of Science Magazine.

"Nothing on Earth comes close to this powerful storm," says Leigh Fletcher, the study's lead author and a Cassini team scientist at the University of Oxford in the United Kingdom. "A storm like this is rare. This is only the sixth one to be recorded since 1876, and the last was way back in 1990."

This is the first major storm on Saturn observed by an orbiting spacecraft and studied at thermal infrared wavelengths, where Saturn's heat energy reveals atmospheric temperatures, winds and composition within the disturbance.

Temperature data were provided by the Very Large Telescope (VLT) on Cerro Paranal in Chile and Cassini's composite infrared spectrometer (CIRS), operated by NASA's Goddard Space Flight Center in Greenbelt, Md.

"Our new observations show that the storm had a major effect on the atmosphere, transporting energy and material over great distances, modifying the atmospheric winds -- creating meandering jet streams and forming giant vortices -- and disrupting Saturn's slow seasonal evolution," said Glenn Orton, a paper co-author, based at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

The violence of the storm -- the strongest disturbances ever detected in Saturn's stratosphere -- took researchers by surprise. What started as an ordinary disturbance deep in Saturn's atmosphere punched through the planet's serene cloud cover to roil the high layer known as the stratosphere.

"On Earth, the lower stratosphere is where commercial airplanes generally fly to avoid storms which can cause turbulence," says Brigette Hesman, a scientist at the University of Maryland in College Park who works on the CIRS team at Goddard and is the second author on the paper. "If you were flying in an airplane on Saturn, this storm would reach so high up, it would probably be impossible to avoid it."

Other indications of the storm's strength are the changes in the composition of the atmosphere brought on by the mixing of air from different layers. CIRS found evidence of such changes by looking at the amounts of acetylene and phosphine, both considered to be tracers of atmospheric motion. A separate analysis using Cassini's visual and infrared mapping spectrometer, led by Kevin Baines of JPL, confirmed the storm is very violent, dredging up larger atmospheric particles and churning up ammonia from deep in the atmosphere in volumes several times larger than previous storms. Other Cassini scientists are studying the evolving storm, and a more extensive picture will emerge soon.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The mission is managed by JPL for NASA's Science Mission Directorate in Washington. The European Southern Observatory in Garching, Germany operates the VLT in Chile. JPL is a division of the California Institute of Technology in Pasadena.

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