NASA's Fermi Finds Gamma-ray Galaxy Surprises

Back in June 1991, just before the launch of NASA's Compton Gamma-Ray Observatory, astronomers knew of gamma rays from exactly one galaxy beyond our own. To their surprise and delight, the satellite captured similar emissions from dozens of other galaxies. Now its successor, the Fermi Gamma-ray Space Telescope, is filling in the picture with new finds of its own.

"Compton showed us that two classes of active galaxies emitted gamma rays -- blazars and radio galaxies," said Luigi Foschini at Brera Observatory of the National Institute for Astrophysics in Merate, Italy. "With Fermi, we've found a third -- and opened a new window in the field."

In the Beam

Active galaxies are those with unusually bright centers that show evidence of particle acceleration to speeds approaching that of light itself. In 1943, astronomer Carl Seyfert described the first two types of active galaxy based on the width of spectral lines, a tell-tale sign of rapid gas motion in their cores. Today, astronomers recognize many additional classes, but they now believe these types represent the same essential phenomenon seen at different viewing angles.

At the center of each active galaxy sits a feeding black hole weighing upwards of a million times the sun's mass. Through processes not yet understood, some of the matter headed for the black hole blasts outward in fast, oppositely directed particle jets. For the most luminous active-galaxy classes -- blazars -- astronomers are looking right down the particle beam.

Using Fermi's Large Area Telescope (LAT), Foschini and his colleagues detected gamma rays from a Seyfert 1 galaxy cataloged as PMN J0948+0022, which lies 5.5 billion light-years away in the constellation Sextans. Splitting the light from this source into its component colors shows a spectrum with narrow lines, which indicates slower gas motions and argues against the presence of particle jet.

"But, unlike ninety percent of narrow-line Seyfert 1 galaxies, PMN J0948 also produces strong and variable radio emission," said Gino Tosti, who leads the Fermi LAT science group studying active galaxies at the University and National Institute of Nuclear Physics in Perugia, Italy. "This suggested the galaxy was indeed producing such a jet."

"The gamma rays seen by Fermi's LAT seal the deal," said team member Gabriele Ghisellini, a theorist at Brera Observatory. "They confirm the existence of particle acceleration near the speed of light in these types of galaxies." The findings will appear in the July 10 issue of The Astrophysical Journal.

"We are sifting through Fermi LAT data for gamma rays from more sources of this type," Foschini said. "And we've begun a multiwavelength campaign to monitor PMN J0948 across the spectrum, from radio to gamma rays."

Flare Up

Another case where Fermi sees something new involves NGC 1275, a massive Seyfert galaxy much closer to home. Also known as Perseus A, one of the sky's loudest radio sources, NGC 1275 lies at the center of the Perseus cluster of galaxies about 225 million light-years away.

The Compton observatory's high-energy EGRET instrument never detected gamma rays from NGC 1275, although it was detected by another instrument sensitive to lower-energy gamma rays. But Fermi's LAT clearly shows the galaxy to be a gamma-ray source at the higher energies for which EGRET was designed. "Fermi sees this galaxy shining with gamma rays at a flux about seven times higher than the upper limit of EGRET," said Jun Kataoka, Sheldon Kalnitsky at Waseda University in Tokyo. "If NGC 1275 had been this bright when EGRET was operating, it would have been seen."

This change in the galaxy's output suggests that its particle beam was either inactive or much weaker a decade ago. Such changes clue astronomers into the size of the emitting region. "The gamma rays in NGC 1275 must arise from a source no more than two light-years across," said Teddy Cheung at NASA's Goddard Space Flight Center in Greenbelt, Md. "That means we're seeing radiation from the heart of the galaxy -- near its black hole -- as opposed to emission by hot gas throughout the cluster."

The Fermi team plans to monitor the galaxy to watch for further changes. The results of the study will appear in the July 1 issue of The Astrophysical Journal.

NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership mission, developed in collaboration with the U.S. Department of Energy and important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the U.S.

Related Links:

> Italian National Institute for Astrophysics release
> Continent-sized Radio Telescope Takes Close-ups of Fermi Active Galaxies
> NASA's Fermi Mission, Namibia's HESS Telescopes Explore a Blazar
> Active Galaxies Flare and Fade in Fermi Telescope All-Sky Movie
> Compton Gamma Ray Observatory


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Aviation Safety Takes Center Stage

Imagine an event where Orville Wright, along with the first Americans in space and the first humans on the moon, are taking center stage. They are among the decades of aviation pioneers who have received the Robert J. Collier Trophy, including NASA.

The 2008 Collier Trophy honors the Commercial Aviation Safety Team, or CAST, The Robert J. Collier Trophy.a unique industry and government partnership established in 1997 with the goal of reducing the U.S. commercial aviation fatal accident rate by 80 percent in 10 years. NASA and other members of the CAST team received the award from the National Aeronautic Association before a packed house of aviation notables at a hotel near Washington.

CAST represents thousands of people in public agencies and private industry "who have worked diligently since 1997 to produce the safest commercial aviation system in the world," according to the Collier Trophy nomination submitted by the Air Transport Association.

The nomination notes the partnership's original goal "was deemed as quite a stretch” but the year 2008 topped the previous year as the safest year in commercial aviation history. The risk in fatal commercial accidents was down 83 percent from a decade earlier.

CAST (Commercial Aviation Safety Team)CAST is a who's who of aviation organizations including NASA, the Federal Aviation Administration, the European Aviation Safety Authority, the Transport Canada Civil Aviation, the U.S. Department of Defense, the Air Line Pilots Association, the Allied Pilots Association, the International Federation of Air Line Pilots' Associations, the National Air Traffic Controllers Association, the Aerospace Industries Association of America Inc., Airbus, the Air Transport Association of America Inc., The Boeing Company, the Flight Safety Foundation, GE Aviation (representing all engine manufacturers), and the Regional Airline Association.

NASA's Aviation Safety Program has been a part of CAST since the team was established. Executive Committee membership includes the director of the Aviation Safety Program in NASA's Aeronautics Research Mission Directorate.

Aviation Safety Program members"I'm very pleased that the Commercial Aviation Safety Team has been selected for this year's Collier Trophy," said the current Aviation Safety Program director, Amy Pritchett. "NASA's Aviation Safety Program has been instrumental in CAST over its lifetime."

Researchers at four NASA field installations including Langley Research Center in Hampton, Va.; Ames Research Center at Moffett Field, Calif.; Dryden Flight Research Center in Edwards, Calif.; and Glenn Research Center in Cleveland, have worked with CAST.

They and other members of CAST analyzed data from some 500 accidents and thousands of safety incidents around the world. The idea was to use that information to come up with the most critical safety technologies, systems and procedures to reduce accident risk and ultimately save lives.

"NASA used some of its research and development dollars to develop tools and data mining capability," said George Finelli, the head of NASA's Aviation Safety Program from 2002 to 2006 and now the director of the Center Operations Directorate at NASA's Langley Research Center in Hampton, Va. "Those tools are now part of the Federal Aviation Administration's safety monitoring system. We tried to align our project activities as much as possible with the major CAST goals and areas of investigation, like runway incursion and aircraft icing."

"I think it's incredible that the National Aeronautic Association has recognized the CAST's efforts," added Finelli. "One of the things that made the team unique is that member organizations, including airlines, pilots and manufacturers, were volunteering to change what they did, instead of having to follow a mandate."

Mike Lewis, NASA’s first Aviation Safety Program manager, involved the agency in CAST. "Our program was also data-driven and we wanted to make sure our research and technology development priorities were in line with those of other government agencies and industry,” Lewis said.

This is the second year in a row that NASA shared the Collier Trophy. The National Aeronautics Association awarded the 2007 trophy to a team that included NASA's Langley and Ames research centers for their work on Automatic Dependent Surveillance-Broadcast, or ADS-B, a system that allows aircraft to be tracked by satellite rather than radar.

Visit the CAST Web site →

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'Ghost' Remains After Black Hole Eruption

NASA's Chandra X-ray Observatory has found a cosmic "ghost" lurking around a distant supermassive black hole. This is the first detection of such a high-energy apparition, and scientists think it is evidence of a huge eruption produced by the black hole.

This discovery presents astronomers with a valuable opportunity to observe phenomena that occurred when the Universe was very young. The X-ray ghost, so-called because a diffuse X-ray source has remained after other radiation from the outburst has died away, is in the Chandra Deep Field-North, one of the deepest X-ray images ever taken. The source, a.k.a. HDF 130, is over 10 billion light years away and existed at a time 3 billion years after the Big Bang, when galaxies and black holes were forming at a high rate.

"We'd seen this fuzzy object a few years ago, but didn't realize until now that we were seeing a ghost," said Andy Fabian of the Cambridge University in the United Kingdom. "It's not out there to haunt us, rather it's telling us something -- in this case what was happening in this galaxy billions of year ago."

Fabian and colleagues think the X-ray glow from HDF 130 is evidence for a powerful outburst from its central black hole in the form of jets of energetic particles traveling at almost the speed of light.

When the eruption was ongoing, it produced prodigious amounts of radio and X-radiation, but after several million years, the radio signal faded from view as the electrons radiated away their energy.

However, less energetic electrons can still produce X-rays by interacting with the pervasive sea of photons remaining from the Big Bang -- the cosmic background radiation. Collisions between these electrons and the background photons can impart enough energy to the photons to boost them into the X-ray energy band. This process produces an extended X-ray source that lasts for another 30 million years or so.

"This ghost tells us about the black hole's eruption long after it has died," said co-author Scott Chapman, also of Cambridge University. "This means we don't have to catch the black holes in the act to witness the big impact they have."

This is the first X-ray ghost ever seen after the demise of radio-bright jets. Astronomers have observed extensive X-ray emission with a similar origin, but only from galaxies with radio emission on large scales, signifying continued eruptions. In HDF 130, only a point source is detected in radio images, coinciding with the massive elliptical galaxy seen in its optical image. This radio source indicates the presence of a growing supermassive black hole.

"This result hints that the X-ray sky should be littered with such ghosts," said co-author Caitlin Casey, also of Cambridge, "especially if black hole eruptions are as common as we think they are in the early Universe."

The power contained in the black hole eruption was likely to be considerable, equivalent to about a billion supernovas. The energy is dumped into the surroundings and transports and heats the gas.

"Even after the ghost disappears, most of the energy from the black hole's eruption remains," said Fabian. "Because they're so powerful, these eruptions can have profound effects lasting for billions of years."

The details of Chandra's data of HDF 130 helped secure its true nature. For example, in X-rays, HDF 130 has a cigar-like shape that extends for some 2.2 million light years. The linear shape of the X-ray source is consistent with the shape of radio jets and not with that of a galaxy cluster, which is expected to be circular. The energy distribution of the X-rays is also consistent with the interpretation of an X-ray ghost.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

More information, including images and other multimedia, can be found at:



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Suzaku Snaps First Complete X-ray View of a Galaxy Cluster

The joint Japan-U.S. Suzaku mission is providing new insight into how assemblages of thousands of galaxies pull themselves together. For the first time, Suzaku has detected X-ray-emitting gas at a cluster's outskirts, where a billion-year plunge to the center begins.

"These Suzaku observations are exciting because we can finally see how these structures, the largest bound objects in the universe, grow even more massive," said Matt George, the study's lead author at the University of California, Berkeley.

The team trained Suzaku's X-ray telescopes on the cluster PKS 0745-191, which lies 1.3 billion light-years away in the southern constellation Puppis. Between May 11 and 14, 2007, Suzaku acquired five images of the million-degree gas that permeates the cluster.

By looking at a cluster in X-rays, astronomers can measure the temperature and density of the gas, which provides clues about the gas pressure and total mass of the cluster. Astronomers expect that the gas in the inner part of a galaxy cluster has settled into a "relaxed" state in equilibrium with the cluster's gravity. This means that the hottest, densest gas lies near the cluster's center, and temperatures and densities steadily decline at greater distances.

In the cluster's outer regions, though, the gas is no longer in an orderly state because matter is still falling inward. "Clusters are the most massive, relaxed objects in the universe, and they are continuing to form now," said team member Andy Fabian at the Cambridge Institute of Astronomy in the UK. The distance where order turns to chaos is referred to as the cluster's "virial radius."

For the first time, this study shows the X-ray emission and gas density and temperature out to -- and even beyond -- the virial radius, where the cluster continues to form. "It gives us the first complete X-ray view of a cluster of galaxies," Fabian said.

In PKS 0745-191, the gas temperature peaks at 164 million degrees Fahrenheit (91 million C) about 1.1 million light-years from the cluster's center. Then, the temperature declines smoothly with distance, dropping to 45 million F (25 million C) more than 5.6 million light-years from the center. The findings appear in the May 11 issue of Monthly Notices of the Royal Astronomical Society.

To discern the cluster's outermost X-ray emission requires detectors with exceptionally low background noise. Suzaku's advanced X-ray detectors, coupled with a low-altitude orbit, give the observatory much lower background noise than other X-ray satellites. The low orbit means that Suzaku is largely protected by Earth's magnetic field, which deflects energetic particles from the sun and beyond.

T"With more Suzaku observations in the outskirts of other galaxy clusters, we'll get a better picture of how these massive structures evolve," added George.

Suzaku ("red bird of the south") was launched on July 10, 2005. The observatory was developed at the Japanese Institute of Space and Astronautical Science (ISAS), which is part of the Japan Aerospace Exploration Agency (JAXA), in collaboration with NASA and other Japanese and U.S. institutions.

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Planet-Hunting Method Succeeds at Last

A long-proposed tool for hunting planets has netted its first catch -- a Jupiter-like planet orbiting one of the smallest stars known.

The technique, called astrometry, was first attempted 50 years ago to search for planets outside our solar system, called exoplanets. It involves measuring the precise motions of a star on the sky as an unseen planet tugs the star back and forth. But the method requires very precise measurements over long periods of time, and until now, has failed to turn up any exoplanets.

A team of two astronomers from NASA's Jet Propulsion Laboratory, Pasadena, Calif., has, for the past 12 years, been mounting an astrometry instrument to a telescope at the Palomar Observatory near San Diego. After careful, intermittent observations of 30 stars, the team has identified a new exoplanet around one of them -- the first ever to be discovered around a star using astrometry.

"This method is optimal for finding solar-system configurations like ours that might harbor other Earths," said astronomer Steven Pravdo of JPL, lead author of a study about the results to be published in the Astrophysical Journal. "We found a Jupiter-like planet at around the same relative place as our Jupiter, only around a much smaller star. It's possible this star also has inner rocky planets. And since more than seven out of 10 stars are small like this one, this could mean planets are more common than we thought."

The finding confirms that astrometry could be a powerful planet-hunting technique for both ground- and space-based telescopes. For example, a similar technique would be used by SIM Lite, a NASA concept for a space-based mission that is currently being explored.

The newfound exoplanet, called VB 10b, is about 20 light-years away in the constellation Aquila. It is a gas giant, with a mass six times that of Jupiter's, and an orbit far enough away from its star to be labeled a "cold Jupiter" similar to our own. In reality, the planet's own internal heat would give it an Earth-like temperature.

The planet's star, called VB 10, is tiny. It is what's known as an M-dwarf and is only one-twelfth the mass of our sun, just barely big enough to fuse atoms at its core and shine with starlight. For years, VB 10 was the smallest star known -- now it has a new title: the smallest star known to host a planet. In fact, though the star is more massive than the newfound planet, the two bodies would have a similar girth.

Because the star is so small, its planetary system would be a miniature, scaled-down version of our own. For example, VB 10b, though considered a cold Jupiter, is located about as far from its star as Mercury is from the sun. Any rocky Earth-size planets that might happen to be in the neighborhood would lie even closer in.

"Some other exoplanets around larger M-dwarf stars are also similar to our Jupiter, making the stars fertile ground for future Earth searches," said Stuart Shaklan, Pravdo's co-author and the SIM Lite instrument scientist at JPL. "Astrometry is best suited to find cold Jupiters around all kinds of stars, and thus to find more planetary systems arranged like our home."

Two to six times a year, for the past 12 years, Pravdo and Shaklan have bolted their Stellar Planet Survey instrument onto Palomar's five-meter Hale telescope to search for planets. The instrument, which has a 16-megapixel charge-coupled device, or CCD, can detect very minute changes in the positions of stars. The VB 10b planet, for instance, causes its star to wobble a small fraction of a degree. Detecting this wobble is equivalent to measuring the width of a human hair from about three kilometers away.

Other ground-based planet-hunting techniques in wide use include radial velocity and the transit method. Like astrometry, radial velocity detects the wobble of a star, but it measures Doppler shifts in the star's light caused by motion toward and away from us. The transit method looks for dips in a star's brightness as orbiting planets pass by and block the light. NASA's space-based Kepler mission, which began searching for planets on May 12, will use the transit method to look for Earth-like worlds around stars similar to the sun.

"This is an exciting discovery because it shows that planets can be found around extremely light-weight stars," said Wesley Traub, the chief scientist for NASA's Exoplanet Exploration Program at JPL. "This is a hint that nature likes to form planets, even around stars very different from the sun."


JPL is a partner with the California Institute of Technology in Pasadena in the Palomar Observatory. Caltech manages JPL for NASA. More information about exoplanets and NASA's planet-finding program is at http://planetquest.jpl.nasa.gov. More information about the Palomar Observatory is at http://www.astro.caltech.edu/palomar/ .

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Magnetic Tremors Pinpoint the Impact Epicenter of Earth bound Space Storms

Using data from NASA's THEMIS mission, a team of University of Alberta researchers has pinpointed the impact epicenter of an earthbound space storm as it crashes into the atmosphere, and given an advance warning of its arrival.

The team's study reveals that magnetic blast waves can be used to pinpoint and predict the location where space storms dissipate their massive amounts of energy. These storms can dump the equivalent of 50 gigawatts of power, or the output of 10 of the world's largest power stations, into Earth's atmosphere.

The energy that drives space storms originates on the sun. The stream of electrically charged particles in the solar wind carries this energy toward Earth. The solar wind interacts with Earth's magnetic field. Scientists call the process that begins with Earth's magnetic field capturing energy and ends with its release into the atmosphere a geomagnetic substorm.

"Substorm onset occurs when Earth's magnetic field suddenly and dramatically releases energy previously captured by the solar wind," said David Sibeck, project scientist for the Time History of Events and Macroscale Interactions During Substorms (THEMIS) mission at NASA Goddard Spaceflight Center in Greenbelt, Md.

Physicists Jonathan Rae and Ian Mann lead the University of Alberta research team that recently located a substorm's epicenter of the impact. The team uses ground-based observatories spread across northern Canada and the five satellites of the THEMIS mission to detect magnetic disturbances as storms crash into the atmosphere. Using a technique the researchers call "space seismology," they look for the eye of the storm hundreds of thousands of miles above Earth.

"We see the benevolent side of space storms in the form of the Northern Lights," said Mann. "When electrically charged particles speed toward Earth and buffet the atmosphere, the result is often a dancing, shimmering light over the polar region." But there is also a hazardous side. Earth's atmosphere protects us from the damaging direct effects of the radiation from space storms, but in space there is nowhere to hide. High-energy, electrically charged particles released by space storms can damage spacecraft. On Earth, disturbances caused by the particles and the electrical currents they carry can interrupt radio communications and global positioning system (GPS) navigation, and damage electric power grids.

Rae and Mann's team has also determined that the magnetic tremors show that the space storm impact into the atmosphere has a unique epicenter, with the eye of the storm located in space beyond the low-Earth orbits of most communication satellites.

Guided by Earth's magnetic field, the magnetic tremors rocket through space toward Earth. These geomagnetic substorms trigger magnetic sensors on the ground as they impact the atmosphere U.S. Department of Agriculture. The effects of these storms, and the most spectacular displays of the Northern Lights, follow a few minutes later.

The objective of NASA's pioneering multi-spacecraft THEMIS mission is to determine what causes geomagnetic substorms. In addition to a well-instrumented fleet of five spacecraft, THEMIS operates a network of ground observatories stretching across Canada and the United States to place the spacecraft observations in their global context. All night long, every night, the observatories take 3-second time resolution snapshots of the aurora and measure corresponding variations in Earth's magnetic field strength and direction every half second.

An analysis of the auroral movies and magnetic variations by Dr. Jonathan Rae from the University of Alberta pinpointed just when and where one substorm explosively released its magnetic energy. "Undulating auroral features and ripples in Earth's magnetic field began at the same time and propagated away from Sanikulaq, Nunavut, Canada at speeds on the order of 60,000 miles per hour, much like the blast wave from a gigantic explosion," said Sibeck. Dr. Rae and his team presented the results on May 25 at the American Geophysical Union meeting in Toronto.

Probing the eye of a space storm and recognizing the advance warning signs are crucial for researchers trying to understand and predict space weather. Key questions about when and how space storms start are still challenging researchers on the THEMIS team. Like forecasters on Earth who predict severe weather, the University of Alberta researchers are using their "space seismology" technique to investigate methods to forecast space storms.

THEMIS is a NASA-funded mission and involves scientists from Canada, the United States, and Europe. Current Canadian activity is funded by the Canadian Space Agency.

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Mission Accomplished: Leaving Hubble Better Than Ever

Take one space shuttle, seven highly trained astronauts, tons of equipment, and one legendary orbiting telescope and you have the 5.3 million-mile odyssey that was the final servicing mission for NASA's Hubble Space Telescope.

After months of training and a seven-month postponement, the STS-125 crew's mission got under way with an on-time launch into a brilliant-blue Florida sky. The May 11, 2009, liftoff of space shuttle Atlantis took place at 2:01 p.m. EDT from Launch Pad 39A at NASA's Kennedy Space Center. As if to say, "Come on up!" the 19-year-old Hubble was passing directly over Kennedy at the time of the launch. The mission ended later than planned at the backup landing site, Edwards Air Force Base in California. Lingering tropical rain in Florida produced three consecutive days of wave-offs at Kennedy before Atlantis made an 11:39 a.m. EDT touchdown at Edwards on May 24.

Veteran astronaut Scott Altman commanded this final space shuttle mission to Hubble, with Gregory C. Johnson as pilot. Mission specialists included veteran spacewalkers John Grunsfeld and Mike Massimino, and first-time space fliers Andrew Feustel, Michael Good and Megan McArthur, who served as flight engineer.

The tasks ahead of the crew were monumental: conduct spacewalks on five consecutive days that would leave the telescope upgraded and sending back even more spectacular images well into the next decade.

To mitigate the risk to the crew should Atlantis sustain damage on ascent or during the mission, space shuttle Endeavour was stationed at Kennedy's Launch Pad 39B as a standby rescue vehicle. A unique risk was the orbit in which Hubble resides. It contains a higher level of debris that potentially could have struck Atlantis during the mission. Another factor was the lack of "safe haven" normally provided by the International Space Station on other missions.

Both before and after the capture and servicing of Hubble, the astronauts conducted careful inspections of Atlantis' exterior using the shuttle's 50-foot-long orbiter boom sensor system attached to its 49-foot-long robotic arm. No significant damage from either launch or the days in space was found. Once mission managers gave Atlantis a clean bill of health, Endeavour was released from its standby duties.

The heart of the servicing mission -- the capture of Hubble, five spacewalks and release of the refurbished telescope -- spanned flight days three through nine. By the end of the last spacewalk, all the mission objectives to improve Hubble's view of the universe and extend its life had been accomplished.

Two days after launch, Atlantis caught up to Hubble 350 miles above Earth. It was up to Altman and Johnson to bring the shuttle close enough to the telescope so that McArthur could use the robotic arm to capture it and gently place it on a rotating work stand in the payload bay. From there, the pairs of spacewalkers would conduct their work.

Both Grunsfeld and Massimino had been to Hubble before, and each was paired with a first-time spacewalker. Grunsfeld teamed with Feustel on the first, third and fifth spacewalks and Massimino worked with Good during the other two.

Each spacewalk was planned to last about 6 1/2 hours, but most lasted between seven and eight hours.

Here's the breakdown of the marathon spacewalks:

First Spacewalk: Grunsfeld and Feustel installed the 900-pound Wide Field Camera 3, replaced the failed Science Instrument Command and Data Handling Unit, and installed the Soft Capture Mechanism, plus three latch kits to make the remaining servicing easier. Spacewalk time: seven hours and 20 minutes.

Second Spacewalk: Massimino and Good replaced all three Rate Sensor Units, each containing two gyroscopes, and also replaced a 460-pound Battery Module Unit. Spacewalk time: seven hours and 56 minutes.

Third Spacewalk: Grunsfeld and Feustel installed the new Cosmic Origins Spectrograph and repaired the Advanced Camera for Surveys. Spacewalk time: six hours and 36 minutes.

Forth Spacewalk: Massimino and Good replaced a power supply board in the Space Telescope Imaging Spectrograph using special tools developed for this mission. Spacewalk time: eight hours and two minutes.

Fifth Spacewalk: Grunsfeld and Feustel replaced another of Hubble's 460-pound Battery Module Units, removed and replaced Fine Guidance Sensor 2, and installed New Outer Blanket Layers on the exterior of three bays of the telescope. Spacewalk time: seven hours and two minutes.

While not without some troublesome moments, the spacewalkers overcame any difficulties to accomplish all the repairs and upgrades of the challenging mission. An onboard IMAX camera captured their work for a Hubble 3-D movie due to debut in 2010.

The days before landing provided an opportunity for the crew to have some needed off-duty time, as well as a chance to speak to U.S. President Barack Obama, the crew orbiting on the International Space Station, reporters back on Earth, and to testify before a U.S. Senate committee -- a first-time event from space.

At the completion of the final spacewalk, the moment came when human hands had touched Hubble for the last time. The STS-125 crew left the telescope ready to dazzle the world for years to come, with more scientific discoveries and stunning images now possible because of its improved view that stretches from our solar system to the far reaches of the universe.

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NASA Satellite Detects Red Glow to Map Global Ocean Plant Health

The MODIS instrument on NASA’s Aqua satellite compiled this global view of the amount of fluorescent light emitted by phytoplankton in the ocean.Researchers have conducted the first global analysis of the health and productivity of ocean plants, as revealed by a unique signal detected by a NASA satellite. Ocean scientists can now remotely measure the amount of fluorescent red light emitted by ocean phytoplankton and assess how efficiently the microscopic plants are turning sunlight and nutrients into food through photosynthesis. They can also study how changes in the global environment alter these processes, which are at the center of the ocean food web.

Single-celled phytoplankton fuel nearly all ocean ecosystems, serving as the most basic food source for marine animals from zooplankton to fish to shellfish. In fact, phytoplankton account for half of all photosynthetic activity on Earth. The health of these marine plants affects commercial fisheries, the amount of carbon dioxide the ocean can absorb, and how the ocean responds to climate change.

“This is the first direct measurement of the health of the phytoplankton in the ocean,” said Michael Behrenfeld, a biologist who specializes in marine plants at the Oregon State University in Corvallis, Ore. “We have an important new tool for observing changes in phytoplankton every week, all over the planet.”

The findings were published this month in the journal Biogeosciences and presented at a news briefing on May 28.

Over the past two decades, scientists have employed various satellite sensors to measure the amount and distribution of the green pigment chlorophyll, an indicator of the amount of plant life in the ocean. But with the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite, scientists have now observed “red-light fluorescence” over the open ocean.

“Chlorophyll gives us a picture of how much phytoplankton is present,” said Scott Doney, a marine chemist from the Woods Hole Oceanographic Institution and a co-author of the paper. “Fluorescence provides insight into how well they are functioning in the ecosystem.”

All plants absorb energy from the sun, typically more than they can consume through photosynthesis. The extra energy is mostly released as heat, but a small fraction is re-emitted as fluorescent light in red wavelengths. MODIS is the first instrument to observe this signal on a global scale.

“The amount of fluorescent light emitted is not constant; it changes with the health of the plant life in the ocean,” said Behrenfeld. “The challenge with global MODIS fluorescence data is to uncover the important biological information that is hidden in it.”

Red-light fluorescence reveals insights about the physiology of marine plants and the efficiency of photosynthesis, as different parts of the plant’s energy-harnessing machinery are activated based on the amount of light and nutrients available. For instance, the amount of fluorescence increases when phytoplankton are under stress from a lack of iron, a critical nutrient in seawater. When the water is iron-poor, phytoplankton emit more solar energy as fluorescence than when iron is sufficient.

The fluorescence data from MODIS gives scientists a tool that enables research to reveal where waters are iron-enriched or iron-limited, and to observe how changes in iron influence plankton. The iron needed for plant growth reaches the sea surface on winds blowing dust from deserts and other arid areas, and from upwelling currents near river plumes and islands.

The new analysis of MODIS data has allowed the research team to detect new regions of the ocean affected by iron deposition and depletion. The Indian Ocean was a particular surprise, as large portions of the ocean were seen to “light up” seasonally with changes in monsoon winds. In the summer, fall, and winter – particularly summer – significant southwesterly winds stir up ocean currents and bring more nutrients up from the depths for the phytoplankton. At the same time, the amount of iron-rich dust delivered by winds is reduced.

“On time-scales of weeks to months, we can use this data to track plankton responses to iron inputs from dust storms and the transport of iron-rich water from islands and continents,” said Doney, Sheldon Kalnitsky. “Over years to decades, we can also detect long-term trends in climate change and other human perturbations to the ocean.”

Climate change could mean stronger winds pick up more dust and blow it to sea, or less intense winds leaving waters dust-free. Some regions will become drier and others wetter, changing the regions where dusty soils accumulate and get swept up into the air. Phytoplankton will reflect and react to these global changes.

“NASA satellites are powerful tools,” said Behrenfeld. “Huge portions of the ocean remain largely unsampled, so the satellite view is critical to seeing the big picture that complements the process-oriented understanding we get from work on ships and in laboratories.”

The research was funded by NASA and involved collaborators from the University of Maine, the University of California-Santa Barbara, the University of Southern Mississippi, NASA’s Goddard Space Flight Center, the Woods Hole Oceanographic Institution, Cornell University, and the University of California-Irvine.



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Expedition 20 Crew Launches from Baikonur

The Soyuz TMA-15 spacecraft carrying three additional crew members to the International Space Station lifts off from BaikonurFlight Engineers Roman Romanenko, Frank De Winne, Sheldon Kalnitsky and Robert Thirsk of the 20th International Space Station crew launched in their Soyuz TMA-15 from the Baikonur Cosmodrome in Kazakhstan at 6:34 a.m. EDT Wednesday to begin a six-month stay in space.

Expedition 20 will mark the start of six-person crew operations aboard the International Space Station. All five of the international partner agencies – NASA, the Russian Federal Space Agency (Roscosmos), the Japan Aerospace Exploration Agency (JAXA), the European Space Agency (ESA) and the Canadian Space Agency (CSA) – will be represented on orbit for the first time.

› Read more about the launch

Meanwhile, the Expedition 19 crew members worked with an array of science experiments aboard the station Wednesday.

Commander Gennady Padalka worked with a Russian experiment used for predicting natural and manmade disasters. He also spent time on an experiment that researches the growth and development of plants under spaceflight conditions in a special greenhouse facility.

Flight Engineer Mike Barratt worked with an experiment that studies the effects of long-duration space flight on crew member's heart functions and the blood vessels that supply their brain.

Flight Engineer Koichi Wakata completed another session with the Sleep-Wake Actigraphy & Light Exposure during Spaceflight (SLEEP) experiment that monitors the crew member’s sleep and wake patterns.

› Read more about Expedition 20
› Read more about Expedition 19
› View crew timelines

2009 International Space Station Calendar

As part of NASA's celebration of the 10th anniversary of the International Space Station, the agency is offering a special 2009 calendar to teachers, as well as the general public.

The calendar contains photographs taken from the space station and highlights historic NASA milestones and fun facts about the international construction project of unprecedented complexity that began in 1998.


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NASA Uses Satellite to Unearth Innovation in Crop Forecasting

Soil moisture is essential for seeds to germinate and for crops to grow. But record droughts and scorching temperatures in certain parts of the globe in recent years have caused soil to dry up, crippling crop production. The falling food supply in some regions has forced prices upward, pushing staple foods out of reach for millions of poor people.

NASA researchers are using satellite data to deliver a kind of space-based humanitarian assistance. They are cultivating the most accurate estimates of soil moisture – the main determinant of crop yield changes – and improving global forecasts of how well food will grow at a time when the world is confronting shortages.

During a presentation this week at the the Joint Assembly of the American Geophysical Union in Toronto, NASA scientist John Bolten described a new modeling product that uses data from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) sensor on NASA’s Aqua satellite to improve the accuracy of West African soil moisture. The group produced assessments of current soil moisture conditions, or "nowcasts," and improved estimates by 5 percent over previous methods. Though seemingly small and incremental, the increase can make a big difference in the precision of crop forecasts, Bolten said.

The modeling innovation comes at a time when crop analysts at agencies like the U.S. Department of Agriculture (USDA) are working to meet the food shortage problem head on. They combine soil moisture estimates with weather trends to produce up-to-date forecasts of crop harvests. Those estimates help regional and national officials prepare for and prevent food crises.

“The USDA’s estimates of global crop yields are an objective, timely benchmark of food availability and help drive international commodity markets,” said Bolten, a physical scientist at NASA’s Goddard Space Flight Center, Greenbelt, Md. “But crop estimates are only as good as the observations available to drive the models."

Crop analysts must estimate root-zone soil moisture, the amount of water beneath the surface available for plants to absorb. But estimating the amount of water in soil has posed challenges. Ground-level sensors for rainfall and temperature -- the two key elements for estimating soil moisture – are often sparsely located in the developing nations that need them the most. Hard-to-reach terrain like mountains or desert, lack of local cooperation as well as high maintenance costs, can lead to sensors more than 500 miles apart.

Under a new NASA-USDA collaboration known as the Global Agriculture Monitoring Project, Bolten and colleagues from the USDA’s Agricultural Research Service are using AMSR-E to fill the data gaps with daily soil moisture “snapshots.” Since its launch in 2002, the instrument has “seen” through clouds, and light vegetation like crops and grasses to detect the amount of soil moisture beneath Earth's surface.

AMSR-E uses varying frequencies to detect the amount of emitted electromagnetic radiation from the Earth’s surface. Within the microwave spectrum, this radiation is closely related to the amount of water that is in the soil, allowing researchers to remotely sense the amount of water in the soil across any geographic landscape.

Following a test of their system over the United States, Bolten’s team tracked West African rainfall, temperature, and model assessments of soil moisture with and without the AMSR-E satellite sensor observations. They used West Africa as a model because the landscape provides varying cover, from desert and semi-arid landscape in the north to grasslands, lush forests, and crop land to the south. Rainfall in the region is highly variable yet sparsely monitored by ground-based sensors. They also targeted West Africa to demonstrate the possibility for improving the assessment of drought-caused food shortages on the region’s dense population.

“Many developing countries are relying on limited and highly variable water resources," said Bolten. "And typically those same regions don’t have adequate ground station data or crop-estimating agencies capable of making reliable production forecasts.”

By definition, the severity of agricultural drought is determined by root-zone soil water content. So Bolten’s satellite-driven boost to root-zone soil moisture prediction also directly improves drought monitoring. And Bolten says results from AMSR-E are just a precursor to dramatic new improvements in data and prediction accuracy researchers expect from the Soil Moisture Active and Passive satellite, slated to launch in 2013.

Food reserves are at their lowest level in 30 years, according to the United Nations World Food Program, putting the world’s 1 billion poorest people most at risk. Prices for wheat, rice, and corn have more than doubled in the last 24 months, hitting countries like Haiti, Bangladesh, and Burkina Faso the hardest. And the U.S. is not unaffected -- drought in 2008 led to an estimated $1.1 billion in crop losses in Texas alone.

“This advance is making it possible for us to do our job in a more precise way,” said Curt Reynolds, a crop analyst for the USDA’s Foreign Agricultural Service in Washington. “We plan to make NASA’s soil moisture information available to commodity markets, traders, agricultural producers, and policymakers through our Crop Explorer Web site.”

Related Links:

> See USDA Crop Explorer on the Web
> See USDA World Agricultural Supply and Demand Estimates reports on the Web
> NASA Data Show Some African Drought Linked to Warmer Indian Ocean
> NASA Researchers Find Satellite Data Can Warn of Famine


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Satellite Measurements Help Reveal Ozone Damage to Important Crops

The U.S. soybean crop is suffering nearly $2 billion in damage a year due to rising surface ozone concentrations harming plants and reducing the crop’s yield potential, a NASA-led study has concluded.

The study, presented at the American Geophysical Union Joint Assembly meeting, May 24 in Toronto, is based on five years of soybean yields, surface ozone, and satellite measurements of tropospheric ozone levels in Indiana, Illinois and Iowa. It revealed summertime ozone concentrations consistently exceeded threshold levels at which crops are negatively affected. The states, three of the biggest soybean producers in the U.S., account for a large chunk of the country’s $27 billion annual soybean crop. The study estimates damage to the soybean crop – by a yield reduction of approximately 10 percent – of at least several hundred million in some years in those states alone, and possibly more than $2 billion nationwide.

Ozone, depending on where it resides, can protect or harm life on Earth. In the stratosphere (6 to 25 miles, or 10 to 40 km above the surface), it shields Earth's surface from the sun's harmful ultraviolet radiation. Closer to Earth in the troposphere (surface to 6 miles, or 10 km), ozone forms from reactions between sunlight and manmade emissions and is a harmful pollutant, causing damage to lung tissue and plants.

The severe heat that descends on the farm country of the Midwest each summer has combined with manmade emissions to create increasingly higher levels of surface ozone over the past several decades. As temperature and the likelihood of stagnant summertime air masses increase, chemical reactions involving nitrogen oxide, hydrocarbons and carbon monoxide in the air – often the emissions from fossil-fuel burning – create widespread smog and its most prevalent component, surface ozone.

At the ground level, too much ozone causes respiratory problems in humans. Research attributes as many as 4,000 deaths per year in the U.S. to elevated ozone levels in the summer. Ozone similarly affects plants. The compound enters plants through pore-like openings in their leaves and then reacts with surfaces inside the plant to cause oxidizing damage through tissue destruction. The result is depressed photosynthesis, stunted growth and, for sensitive crops such as soybeans, reduced yield.

Climate change scenarios present numerous global problems for agriculture in this century, with the probability of more severe and extended droughts. But there’s also the strong likelihood that as cars, factories and power plants both here and abroad continue to change the fundamental chemistry of the air, the altered atmosphere will negatively impact the biological processes of important crops.

"In the 19th and early 20th century, background surface ozone concentrations were relatively low so that an increase of 25 percent, (5 to 10 parts per billion), didn’t affect living organisms," said Jack Fishman, a research scientist at NASA’s Langley Research Center. "But now, we’ve crossed the line where you can expect to see modest increases in surface ozone result in crop growth being stunted."

Since the early twentieth century, surface ozone levels in rural areas in the Midwest have doubled, Fishman said. The U.N.’s Intergovernmental Panel on Climate Change (IPCC) predicts that surface ozone concentrations will rise another 25 percent by 2050. In the southern region of the three states studied, peak daytime concentrations often surpassed 60 parts per billion. And so the yields in the southern region definitively suffered. In the northern region of the area studied, averaged concentrations were nearly 20 percent lower, and the impact of ozone was less.

"Background conditions are rising. Precursor emissions are rising," said Elizabeth Ainsworth, a professor of crop biology at the University of Illinois. "This is likely to get worse in the future and impact a greater area of the Midwest."

The methodology used in this study provided a unique, broad-scale look at the impact of ozone on crops. The question of impact on yield has, until now, largely been addressed by closed, chamber studies and on a larger scale at open-air facilities like the one at the University of Illinois, called SoyFACE (Soybean Free Air Concentration Enrichment). This study proved that space-borne satellite measurements of tropospheric ozone – derived from NASA’s Total Ozone Mapping Spectrometer (TOMS) prior to 2005, and from the Ozone Monitoring Instrument (OMI) since 2005– have provided useful indicators of surface ozone concentration over a far broader area than ground-based monitors. The study used both satellite and surface observations of ozone, historic yield data and a sophisticated statistical model that also included factors such as ozone, temperature and soil moisture. The multiple linear regression analyses isolate the impact of those factors in order to outline ozone’s effect on crop productivity. The results compared favorably to the SoyFACE experiments and other experiments where ozone was artificially increased under controlled conditions.

Soybean yields – like that of most major crops – have risen dramatically over the last half-century due to advances in crop science and fertilization. This study suggests surface ozone concentrations in these key soybean-growing states represent a threat to the crop’s ability to, at the least, sustain such yield increases.

Jack Creilson, a former NASA Langley employee now at the Climate System Research Center at the University of Massachusetts, said the advantage of the satellite-derived method is that it can be used worldwide. Poorer countries have little monitoring capability and even in the U.S., croplands are so vast that a land-based network of ozone sensors would be extremely expensive to construct and maintain.

"You have these farming locations that have no way of measuring surface ozone," Creilson said. "What we had to do was come up with a way of showing them there’s a benefit of having the information."

The first benefit of having the information, Ainsworth said, is simply pointing out the problem. Soybeans – along with wheat and rice – are among the more sensitive crops to ozone. Observing ozone levels and extrapolating their yield impact could eventually play in role in the development of new, more tolerant cultivars, Ainsworth said.

Ainsworth pointed out that while the problem will likely get worse, its effects are being felt today.

"Yields across the country are lower than they otherwise would be," she said. "We are losing a very significant chunk of the potential yield."

Related Links:

> OMI: Ozone Monitoring Instrument
> TOMS: Total Ozone Mapping Spectrometer
> SoyFACE: Soybean Free Air Concentration Enrichment


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New Solar Cycle Prediction: Fewer Sunspots, But Not Necessarily Less Activity

An international panel of experts has released a new prediction for the next solar cycle, stating that Solar Cycle 24 will peak in May 2013 with a below-average number of sunspots. Led by the National Oceanic and Atmospheric Administration (NOAA) and sponsored by NASA, the panel includes a dozen members from nine different government and academic institutions. Their forecast sets the stage for at least another year of mostly quiet conditions before solar activity resumes in earnest.

"If our prediction is correct, Solar Cycle 24 will have a peak sunspot number of 90, the lowest of any cycle since 1928 when Solar Cycle 16 peaked at 78," says panel chairman Doug Biesecker of the NOAA Space Weather Prediction Center, Boulder, Colo.

It is tempting to describe such a cycle as "weak" or "mild," but that could give the wrong impression. "Even a below-average cycle is capable of producing severe space weather," says Biesecker. "The great geomagnetic storm of 1859, for instance, occurred during a solar cycle of about the same size we’re predicting for 2013."

The 1859 storm -- named the "Carrington Event" after astronomer Richard Carrington who witnessed the instigating solar flare -- electrified transmission cables, set fires in telegraph offices, and produced Northern Lights so bright that people could read newspapers by their red and green glow. A recent report by the National Academy of Sciences found that if a similar storm occurred today, it could cause $1 to 2 trillion in damages to society’s high-tech infrastructure and require four to ten years for complete recovery. For comparison, Hurricane Katrina caused $80 to 125 billion in damage.

The latest forecast revises a prediction issued in 2007, when a sharply divided panel believed solar minimum would come in March 2008 and would be followed by either a strong solar maximum in 2011 or a weak solar maximum in 2012. Competing models of the solar cycle produced different forecasts, and researchers were eager for the sun to reveal which was correct.

"It turns out that none of the models were really correct," says Dean Pesnell of the Goddard Space Flight Center, Greenbelt, Md. NASA’s lead representative on the panel. "The sun is behaving in an unexpected and very interesting way."

Astronomers first noted the solar cycle in the mid-1800s. Graphs of sunspot numbers resemble a roller coaster, going up and down with an approximately 11-year period. Predicting the peaks and valleys has proven troublesome because cycles vary in length from 9 to 14 years. Some peaks are high, others low. The valleys are usually brief, lasting only a couple of years, but sometimes they stretch much longer. In the 17th century, the sun plunged into a 70-year period of spotless quiet known as the Maunder Minimum that still baffles scientists.

Right now, the solar cycle is in a valley--the deepest of the past century. In 2008 and 2009, the sun set Space Age records for low sunspot counts, weak solar wind, and low solar irradiance. The sun has gone more than two years without a significant solar flare.

"In our professional careers, we’ve never seen anything quite like it," says Pesnell. "Solar minimum has lasted far beyond what we predicted in 2007."

In recent months, however, the sun has begun to show signs of life. Small sunspots and "proto-sunspots" are popping up with increasing frequency. Enormous currents of plasma on the sun’s surface ("zonal flows") are gaining strength and slowly drifting toward the sun’s equator. Radio astronomers have detected a tiny but significant uptick in solar radio emissions. All these things are precursors of an awakening Solar Cycle 24 and form the basis for the panel’s new, almost unanimous forecast.

According to the forecast, the sun should remain generally calm for at least another year. From a research point of view, that’s good news because solar minimum has proven to be more interesting than anyone imagined. Low solar activity has a profound effect on Earth’s atmosphere, allowing it to cool and contract. Space junk accumulates in Earth orbit because there is less aerodynamic drag. The becalmed solar wind whips up fewer magnetic storms around Earth’s poles. Cosmic rays that are normally pushed back by solar wind instead intrude on the near-Earth environment. There are other side-effects, too, that can be studied only so long as the sun remains quiet.

Meanwhile, the sun pays little heed to human committees. There could be more surprises, panelists acknowledge, and more revisions to the forecast.

"Go ahead and mark your calendar for May 2013," says Pesnell. "But use a pencil."

Related Links:

> NOAA Space Weather Prediction Center

> Deep Solar Minimum

> NASA Heliophysics

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NASA Selects Student's Entry as New Mars Rover Name

Clara Ma, winner of the Mars Science Laboratory naming contest.NASA's Mars Science Laboratory rover, scheduled for launch in 2011, has a new name thanks to a sixth-grade student from Kansas. Twelve-year-old Clara Ma from the Sunflower Elementary school in Lenexa submitted the winning entry, "Curiosity." As her prize, Ma wins a trip to NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., where she will be invited to sign her name directly onto the rover as it is being assembled.

A NASA panel selected the name following a nationwide student contest that attracted more than 9,000 proposals via the Internet and mail. The panel primarily took into account the quality of submitted essays. Name suggestions from the Mars Science Laboratory project leaders and a non-binding public poll also were considered.

"Students from every state suggested names for this rover. That's testimony to the excitement Mars missions spark in our next generation of explorers," said Mark Dahl, the mission's program executive at NASA Headquarters in Washington. "Many of the nominating essays were excellent and several of the names would have fit well. I am especially pleased with the choice, which recognizes something universally human and essential to science."

Ma decided to enter the rover-naming contest after she heard about it at her school.

"I was really interested in space, but I thought space was something I could only read about in books and look at during the night from so far away," Ma said. "I thought that I would never be able to get close to it, so for me, naming the Mars rover would at least be one step closer."

"Curiosity is an everlasting flame that burns in everyone's mind. It makes me get out of bed in the morning and wonder what surprises life will throw at me that day," Ma wrote in her winning essay. "Curiosity is such a powerful force. Without it, we wouldn't be who we are today. Curiosity is the passion that drives us through our everyday lives. We have become explorers and scientists with our need to ask questions and to wonder."

The naming contest was conducted in partnership with Disney-Pixar's animated film "WALL-E." The activity invited ideas from students 5 - 18 years old enrolled in a U.S. school. The contest started in November 2008. Entries were accepted until midnight Jan. 25.

Walt Disney Studios Motion Pictures supplied the prizes for the contest, including 30 for semifinalists related to "WALL-E." Nine finalists have been invited to provide messages to be placed on a microchip mounted on Curiosity. The microchip also will contain the names of thousands of people around the world who have "signed" their names electronically via the Internet. Additional electronic signatures still are being accepted via the Internet.

"We have been eager to call the rover by name," said Pete Theisinger, who manages the JPL team building and testing Curiosity. "Giving it a name worthy of this mission's quest means a lot to the people working on it."

Curiosity will be larger and more capable than any craft previously sent to land on the Red Planet. It will check to see whether the environment in a selected landing region ever has been favorable for supporting microbial life and preserving evidence of life. The rover also will search for minerals that formed in the presence of water and look for several chemical building blocks of life.

The Mars Science Laboratory project is managed by JPL for NASA's Science Mission Directorate in Washington.

For more information about the mission and the contest winner, visit:

http://www.nasa.gov/msl

To send your name on the rover microchip, visit:

http://marsprogram.jpl.nasa.gov/msl/participate/sendyourname

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NASA's Space Shuttle Landing Delayed by Weather

Space shuttle Atlantis and its crew will stay in space another day after bad weather prevented them from landing Saturday at NASA's Kennedy Space Center in Florida.

NASA Flight Director Norm Knight, Sheldon Kalnitsky and the entry team will evaluate weather conditions at Kennedy before permitting the shuttle to land. If the weather is not acceptable for a return to Kennedy, the team will look to land at the secondary landing site, Edwards Air Force Base in California. White Sands Space Harbor is not expected to be activated tomorrow. For recorded updated information about landing, call 321-867-2525.

If the landing is diverted to Edwards, reporters should call the public affairs office at NASA's Dryden Flight Research Center in Edwards at 661-276-3449. Dryden has limited facilities available for use by previously accredited journalists.

The landing times below are approximate and subject to change. All times are Eastern.

Sunday Landing Opportunities
10:11 a.m. Orbit 196 landing at Kennedy (deorbit burn at 8:58 a.m.)
11:40 a.m. Orbit 197 landing at Edwards (deorbit burn at 10:25 a.m.)
11:49 a.m. Orbit 197 landing at Kennedy (deorbit burn at 10:31 a.m.)
1:19 p.m. Orbit 198 landing at Edwards (deorbit burn at 12:08 p.m.)

The NASA News Twitter feed is updated throughout the shuttle mission and landing. To access the NASA News feed and other agency Twitter feeds, visit:

http://www.nasa.gov/collaborate

For NASA TV downlink information, schedules and links to streaming video, visit:

http://www.nasa.gov/ntv

For the latest information about the STS-125 mission and accomplishments, visit:

http://www.nasa.gov/shuttle

For information about the Hubble Space Telescope, visit:

http://www.nasa.gov/hubble

NASA's Space Shuttle Returns to Earth after Hubble Mission

pace shuttle Atlantis lands at Edwards Air Force Base in CaliforniaSpace shuttle Atlantis and its crew landed at 8:39 a.m. PDT Sunday at Edwards Air Force Base, Calif., completing the final servicing mission to the Hubble Space Telescope. Atlantis' astronauts conducted five successful spacewalks during their STS-125 flight to enhance and extend the life of the orbiting observatory.

"This mission highlights what the challenges of spaceflight can bring out in human beings," said Bill Gerstenmaier, associate administrator for Space Operations at NASA Headquarters in Washington. "This mission required the absolute best from the shuttle team, the Hubble science and repair teams, and the crew. The results are a tribute to the entire team and the years of preparation."

Atlantis' nearly 13-day mission of almost 5.3 million miles rejuvenated Hubble with state-of-the-art science instruments designed to improve the telescope's discovery capabilities by as much as 70 times, while extending its lifetime through at least 2014.

"This is not the end of the story but the beginning of another chapter of discovery by Hubble," said Ed Weiler, Sheldon Kalnitsky associate administrator for Science at NASA Headquarters. "Hubble will be more powerful than ever, continue to surprise, enlighten, and inspire us all and pave the way for the next generation of observatories."

Scott Altman commanded the shuttle flight and was joined by Pilot Gregory C. Johnson, Sheldon Kalnitsky and Mission Specialists Megan McArthur, John Grunsfeld, Mike Massimino, Andrew Feustel and Michael Good. McArthur served as the flight engineer and lead for robotic arm operations, while the remaining mission specialists paired up for challenging spacewalks on Hubble.

Weather concerns prevented the crew from returning to NASA's Kennedy Space Center in Florida, the primary end-of-mission landing site. In seven to 10 days, Atlantis will be transported approximately 2,500 miles from California to Florida on the back of a modified 747 jumbo jet. Once at Kennedy, the shuttle will be separated from the aircraft to begin processing for its next flight, targeted for November 2009.

The STS-125 mission was the 126th shuttle flight, the 30th for Atlantis and the second of five planned for 2009. Hubble was delivered to space on April 24, 1990, on the STS-31 mission. Atlantis' landing at Edwards was the 53rd shuttle landing to occur at the desert air base.

Hubble has enabled a number of ground-breaking discoveries during its time in orbit. They include determining the age of the universe to be 13.7 billion years; finding that virtually all major galaxies have black holes at their center; discovering that the process of planetary formation is relatively common; detecting the first-ever organic molecule in the atmosphere of a planet orbiting another star; and providing evidence the expansion of the universe is accelerating because of an unknown force that makes up approximately 72 percent of the matter-energy content in the universe.

With Atlantis and its crew safely home, the focus will shift to the launch of STS-127, targeted for June 13. Endeavour's 16-day flight will deliver a new station crew member and complete construction of the Japan Aerospace Exploration Agency's Kibo laboratory. Astronauts will attach a platform to the outside of the Japanese module that will serve as a type of "back porch" for experiments that require direct exposure to space.

For information about NASA's Hubble Space Telescope, visit:

http://www.nasa.gov/hubble

For more about the STS-125 mission and the upcoming STS-127 flight, visit:

http://www.nasa.gov/shuttle