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NASA Probe Sees Solar Wind Decline

The 33-year odyssey of NASA's Voyager 1 spacecraft has reached a distant point at the edge of our solar system where there is no outward motion of solar wind. Now hurtling toward interstellar space some 17.4 billion...

Super-Earth Atmosphere

A team of astronomers, including two NASA Sagan Fellows, has made the first characterizations of a super-Earth's atmosphere, by using a ground-based telescope...

Kepler Discovers

NASA's Kepler spacecraft has discovered the first confirmed planetary system with more than one planet crossing in front of, or transiting, the same star...

Pulverized Planet

Tight double-star systems might not be the best places for life to spring up, according to a new study using data from NASA's Spitzer Space Telescope....

Dark Asteroids

NASA is set to launch a sensitive new infrared telescope to seek out sneaky things in the night sky -- among them, dark asteroids that could pose a threat to Earth....

Archive for May 2011

Space shuttle Endeavour and its crew of six astronauts are to return to Earth in the early morning of June 1, 2011, to complete the STS-134 mission, the last of Endeavour's spacegoing career. Landing is scheduled for 2:35 a.m. EDT. The mission launched Monday, May 16, 2011, at 8:56 a.m. EDT on a mission to the International Space Station.

We will cover Endeavour's return to NASA's Kennedy Space Center in Florida from the Air Traffic Control Tower at the Shuttle Landing Facility at Kennedy beginning at 1 a.m. Wednesday.

Tiny crystals of a green mineral called olivine are falling down like rain on a burgeoning star, according to observations from NASA's Spitzer Space Telescope.

This is the first time such crystals have been observed in the dusty clouds of gas that collapse around forming stars. Astronomers are still debating how the crystals got there, but the most likely culprits are jets of gas blasting away from the embryonic star.

"You need temperatures as hot as lava to make these crystals," said Tom Megeath of the University of Toledo in Ohio. He is the principal investigator of the research and the second author of a new study appearing in Astrophysical Journal Letters. "We propose that the crystals were cooked up near the surface of the forming star, then carried up into the surrounding cloud where temperatures are much colder, and ultimately fell down again like glitter."

Spitzer's infrared detectors spotted the crystal rain around a distant, sun-like embryonic star, or protostar, referred to as HOPS-68, in the constellation Orion.

The crystals are in the form of forsterite. They belong to the olivine family of silicate minerals and can be found everywhere from a periodot gemstone to the green sand beaches of Hawaii to remote galaxies. NASA's Stardust and Deep Impact missions both detected the crystals in their close-up studies of comets.

"If you could somehow transport yourself inside this protostar's collapsing gas cloud, it would be very dark," said Charles Poteet, lead author of the new study, also from the University of Toledo. "But the tiny crystals might catch whatever light is present, resulting in a green sparkle against a black, dusty backdrop."

Forsterite crystals were spotted before in the swirling, planet-forming disks that surround young stars. The discovery of the crystals in the outer collapsing cloud of a proto-star is surprising because of the cloud's colder temperatures, about minus 280 degrees Fahrenheit (minus 170 degrees Celsius). This led the team of astronomers to speculate the jets may in fact be transporting the cooked-up crystals to the chilly outer cloud.

The findings might also explain why comets, which form in the frigid outskirts of our solar system, contain the same type of crystals. Comets are born in regions where water is frozen, much colder than the searing temperatures needed to form the crystals, approximately 1,300 degrees Fahrenheit (700 degrees Celsius). The leading theory on how comets acquired the crystals is that materials in our young solar system mingled together in a planet-forming disk. In this scenario, materials that formed near the sun, such as the crystals, eventually migrated out to the outer, cooler regions of the solar system.

Poteet and his colleagues say this scenario could still be true but speculate that jets might have lifted crystals into the collapsing cloud of gas surrounding our early sun before raining onto the outer regions of our forming solar system. Eventually, the crystals would have been frozen into comets. The Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions, also participated in the study by characterizing the forming star.

"Infrared telescopes such as Spitzer and now Herschel are providing an exciting picture of how all the ingredients of the cosmic stew that makes planetary systems are blended together," said Bill Danchi, senior astrophysicist and program scientist at NASA Headquarters in Washington.

The Spitzer observations were made before it used up its liquid coolant in May 2009 and began its warm mission.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the Spitzer Space Telescope mission for the agency's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

At 11:55 p.m. EDT, space shuttle Endeavour undocked from the International Space Station. Endeavour spent 11 days, 17 hrs and 41 minutes docked to the orbiting laboratory. At undocking, the spacecraft were 215 miles above LaPaz, Bolivia.

The fly around of the space station will begin at 12:22 a.m., with Pilot Greg Johnson maneuvering Endeavour to circle the station at a distance of about 600 feet. The shuttle crew members will take detailed photographs of the external structure of the station, which serves as important documentation for the ground teams in Houston to monitor the orbiting laboratory.

Once the shuttle completes 1.5 revolutions of the complex, Johnson will fire Endeavour’s jets to leave the area. Nearly two hours after undocking a second firing of the engines, which would normally take the shuttle further away, will serve as the first maneuver to bring Endeavour back toward the station for the Sensor Test for Orion Relative-navigation Risk Mitigation, or STORRM. Commander Mark Kelly will pilot Endeavour for the re-rendezvous.

The test will characterize the performance of sensors in Endeavour’s payload bay and acquisition of reflectors on the shuttle’s docking target at the station. The re-rendezvous will mimic the Orion vehicle’s planned rendezvous trajectory and will approach no closer than 600 feet to the station. Endeavour is targeted to approach the station to a point 1,000 feet below and 300 feet behind the station at its closest point.

NASA will launch a spacecraft to an asteroid in 2016 and use a robotic arm to pluck samples that could better explain our solar system's formation and how life began. The mission, called Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer, or OSIRIS-REx, will be the first U.S. mission to carry samples from an asteroid back to Earth.

"This is a critical step in meeting the objectives outlined by President Obama to extend our reach beyond low-Earth orbit and explore into deep space," said NASA Administrator Charlie Bolden. "It’s robotic missions like these that will pave the way for future human space missions to an asteroid and other deep space destinations."

NASA selected OSIRIS-REx after reviewing three concept study reports for new scientific missions, which also included a sample return mission from the far side of the Moon and a mission to the surface of Venus.

Asteroids are leftovers formed from the cloud of gas and dust -- the solar nebula -- that collapsed to form our sun and the planets about 4.5 billion years ago. As such, they contain the original material from the solar nebula, which can tell us about the conditions of our solar system's birth.

After traveling four years, OSIRIS-REx will approach the primitive, near Earth asteroid designated 1999 RQ36 in 2020. Once within three miles of the asteroid, the spacecraft will begin six months of comprehensive surface mapping. The science team then will pick a location from where the spacecraft's arm will take a sample. The spacecraft gradually will move closer to the site, and the arm will extend to collect more than two ounces of material for return to Earth in 2023. The mission, excluding the launch vehicle, is expected to cost approximately $800 million.

The sample will be stored in a capsule that will land at Utah's Test and Training Range in 2023. The capsule's design will be similar to that used by NASA's Stardust spacecraft, which returned the world's first comet particles from comet Wild 2 in 2006. The OSIRIS-REx sample capsule will be taken to NASA's Johnson Space Center in Houston. The material will be removed and delivered to a dedicated research facility following stringent planetary protection protocol. Precise analysis will be performed that cannot be duplicated by spacecraft-based instruments.

RQ36 is approximately 1,900 feet in diameter or roughly the size of five football fields. The asteroid, little altered over time, is likely to represent a snapshot of our solar system's infancy. The asteroid also is likely rich in carbon, a key element in the organic molecules necessary for life. Organic molecules have been found in meteorite and comet samples, indicating some of life's ingredients can be created in space. Scientists want to see if they also are present on RQ36.

"This asteroid is a time capsule from the birth of our solar system and ushers in a new era of planetary exploration," said Jim Green, director, NASA's Planetary Science Division in Washington. "The knowledge from the mission also will help us to develop methods to better track the orbits of asteroids."

The mission will accurately measure the "Yarkovsky effect" for the first time. The effect is a small push caused by the sun on an asteroid, as it absorbs sunlight and re-emits that energy as heat. The small push adds up over time, but it is uneven due to an asteroid's shape, wobble, surface composition and rotation. For scientists to predict an Earth-approaching asteroid's path, they must understand how the effect will change its orbit. OSIRIS-REx will help refine RQ36's orbit to ascertain its trajectory and devise future strategies to mitigate possible Earth impacts from celestial objects.

Michael Drake of the University of Arizona in Tucson is the mission's principal investigator. NASA's Goddard Space Flight Center in Greenbelt, Md., will provide overall mission management, systems engineering, and safety and mission assurance. Lockheed Martin Space Systems in Denver will build the spacecraft. The OSIRIS-REx payload includes instruments from the University of Arizona, Goddard, Arizona State University in Tempe and the Canadian Space Agency. NASA’s Ames Research Center at Moffett Field, Calif., the Langley Research Center in Hampton Va., and the Jet Propulsion Laboratory in Pasadena, Calif., also are involved. The science team is composed of numerous researchers from universities, private and government agencies.

This is the third mission in NASA's New Frontiers Program. The first, New Horizons, was launched in 2006. It will fly by the Pluto-Charon system in July 2015, then target another Kuiper Belt object for study. The second mission, Juno, will launch in August to become the first spacecraft to orbit Jupiter from pole to pole and study the giant planet's atmosphere and interior. NASA's Marshall Space Flight Center in Huntsville, Ala., manages New Frontiers for the agency's Science Mission Directorate in Washington.

NASA's twin lunar probes have arrived in Florida to begin final preparations for a launch in late summer. The two Gravity Recovery And Interior Laboratory spacecraft (Grail) were shipped from Lockheed Martin Space Systems, Denver, to the Astrotech payload processing facility in Titusville, Fla., Friday, May 20. NASA's dynamic duo will orbit the moon to determine the structure of the lunar interior from crust to core and to advance understanding of the thermal evolution of the moon.

"NASA's lunar twins have arrived at Cape Canaveral," said Maria Zuber, Grail's principal investigator, based at the Massachusetts Institute of Technology, in Cambridge. "We're only a few full moons away from a mission that will reveal clues not only into the history of the moon and Earth, but will provide important data for future lunar exploration."

The Grail twins, known as Grail-A and Grail-B, were removed from their shipping containers Monday, May 23. Later this week, they will begin functional testing to verify their state of health after their ride on an Air Force transport jet from Colorado. Over the next four months at the Astrotech facility, the spacecraft will undergo final testing, fueling and packaging in the shroud that will protect them as the Delta II launch vehicle lifts them into space. The spacecraft will then be transported to the Cape Canaveral Air Force Station for installation atop the rocket that will carry them toward the moon.

Grail will be carried into space aboard a United Launch Alliance Delta II Heavy rocket lifting off from Launch Complex-19 at the Cape Canaveral Air Force Station in Florida. The launch period opens Sept. 8, 2011, and extends through Oct. 19. For a Sept. 8 liftoff, the launch window opens at 5:37 a.m. PDT (8:37 a.m. EDT) and remains open through 6:16 a.m. PDT.

Grail-A and Grail-B will fly in tandem orbits around the moon for several months to measure its gravity field in unprecedented detail. The mission will also answer longstanding questions about Earth's moon, and provide scientists a better understanding of how Earth and other rocky planets in the solar system formed.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Grail mission. The Massachusetts Institute of Technology, Cambridge, is home to the mission's principal investigator, Maria Zuber. The Grail mission is part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the spacecraft. Launch management for the mission is the responsibility of NASA's Launch Services Program at the Kennedy Space Center in Florida. JPL is a division of the California Institute of Technology in Pasadena.

An international team, including NASA-funded researchers, using radio telescopes located throughout the Southern Hemisphere has produced the most detailed image of particle jets erupting from a supermassive black hole in a nearby galaxy.

"These jets arise as infalling matter approaches the black hole, but we don't yet know the details of how they form and maintain themselves," said Cornelia Mueller, the study's lead author and a doctoral student at the University of Erlangen-Nuremberg in Germany.

The new image shows a region less than 4.2 light-years across -- less than the distance between our sun and the nearest star. Radio-emitting features as small as 15 light-days can be seen, making this the highest-resolution view of galactic jets ever made. The study will appear in the June issue of Astronomy and Astrophysics and is available online.

Mueller and her team targeted Centaurus A (Cen A), a nearby galaxy with a supermassive black hole weighing 55 million times the sun's mass. Also known as NGC 5128, Cen A is located about 12 million light-years away in the constellation Centaurus and is one of the first celestial radio sources identified with a galaxy.

Seen in radio waves, Cen A is one of the biggest and brightest objects in the sky, nearly 20 times the apparent size of a full moon. This is because the visible galaxy lies nestled between a pair of giant radio-emitting lobes, each nearly a million light-years long.

These lobes are filled with matter streaming from particle jets near the galaxy's central black hole. Astronomers estimate that matter near the base of these jets races outward at about one-third the speed of light.

Using an intercontinental array of nine radio telescopes, researchers for the TANAMI (Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry) project were able to effectively zoom into the galaxy's innermost realm.

"Advanced computer techniques allow us to combine data from the individual telescopes to yield images with the sharpness of a single giant telescope, one nearly as large as Earth itself," said Roopesh Ojha at NASA's Goddard Space Flight Center in Greenbelt, Md.

The enormous energy output of galaxies like Cen A comes from gas falling toward a black hole weighing millions of times the sun's mass. Through processes not fully understood, some of this infalling matter is ejected in opposing jets at a substantial fraction of the speed of light. Detailed views of the jet's structure will help astronomers determine how they form.

The jets strongly interact with surrounding gas, at times possibly changing a galaxy's rate of star formation. Jets play an important but poorly understood role in the formation and evolution of galaxies.

NASA's Fermi Gamma-ray Space Telescope has detected much higher-energy radiation from Cen A's central region. "This radiation is billions of times more energetic than the radio waves we detect, and exactly where it originates remains a mystery," said Matthias Kadler at the University of Wuerzburg in Germany and a collaborator of Ojha. "With TANAMI, we hope to probe the galaxy's innermost depths to find out."

Ojha is funded through a Fermi investigation on multiwavelength studies of Active Galactic Nuclei. The astronomers credit continuing improvements in the Australian Long Baseline Array (LBA) with TANAMI's enormously increased image quality and resolution. The project augments the LBA with telescopes in South Africa, Chile and Antarctica to explore the brightest galactic jets in the southern sky.

NASA’s Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the U.S. The Australia Long Baseline Array is part of the Australia Telescope National Facility, which is funded by the Commonwealth of Australia for operation as a National Facility managed by the Commonwealth Scientific and Industrial Research Organization.

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.

Final preparations are under way for the June 9 launch of the international Aquarius/SAC-D observatory. The mission's primary instrument, Aquarius, will study interactions between ocean circulation, the water cycle and climate by measuring ocean surface salinity. 

Engineers at Vandenberg Air Force Base in California are performing final tests before mating Aquarius/SAC-D to its Delta II rocket. The mission is a collaboration between NASA and Argentina's space agency, Comision Nacional de Actividades Espaciales (CONAE), with participation from Brazil, Canada, France and Italy. SAC stands for Satelite de Applicaciones Cientificas. Aquarius was built by NASA's Jet Propulsion Laboratory in Pasadena, Calif., and the agency's Goddard Space Flight Center in Greenbelt, Md.
In addition to Aquarius, the observatory carries seven other instruments that will collect environmental data for a wide range of applications, including studies of natural hazards, air quality, land processes and epidemiology. 

The mission will make NASA's first space observations of the concentration of dissolved salt at the ocean surface. Aquarius' observations will reveal how salinity variations influence ocean circulation, trace the path of freshwater around our planet, and help drive Earth's climate. The ocean surface constantly exchanges water and heat with Earth's atmosphere. Approximately 80 percent of the global water cycle that moves freshwater from the ocean to the atmosphere to the land and back to the ocean happens over the ocean. 

Salinity plays a key role in these exchanges. By tracking changes in ocean surface salinity, Aquarius will monitor variations in the water cycle caused by evaporation and precipitation over the ocean, river runoff, and the freezing and melting of sea ice. 

Salinity also makes seawater denser, causing it to sink, where it becomes part of deep, interconnected ocean currents. This deep ocean "conveyor belt" moves water masses and heat from the tropics to the polar regions, helping to regulate Earth's climate. 

"Salinity is the glue that bonds two major components of Earth's complex climate system: ocean circulation and the global water cycle," said Aquarius Principal Investigator Gary Lagerloef of Earth & Space Research in Seattle. "Aquarius will map global variations in salinity in unprecedented detail, leading to new discoveries that will improve our ability to predict future climate." 

Aquarius will measure salinity by sensing microwave emissions from the water's surface with a radiometer instrument. These emissions can be used to indicate the saltiness of the surface water, after accounting for other environmental factors. Salinity levels in the open ocean vary by only about five parts per thousand, and small changes are important. Aquarius uses advanced technologies to detect changes in salinity as small as about two parts per 10,000, equivalent to a pinch (about one-eighth of a teaspoon) of salt in a gallon of water. 

Aquarius will map the entire open ocean every seven days for at least three years from 408 miles (657 kilometers) above Earth. Its measurements will produce monthly estimates of ocean surface salinity with a spatial resolution of 93 miles (150 kilometers). The data will reveal how salinity changes over time and from one part of the ocean to another. 

The Aquarius/SAC-D mission continues NASA and CONAE's 17-year partnership. NASA provided launch vehicles and operations for three SAC satellite missions and science instruments for two. 

JPL will manage Aquarius through its commissioning phase and archive mission data. Goddard will manage Aquarius mission operations and process science data. NASA's Launch Services Program at the agency's Kennedy Space Center in Florida is managing the launch. 

CONAE is providing the SAC-D spacecraft, an optical camera, a thermal camera in collaboration with Canada, a microwave radiometer,; sensors from various Argentine institutions and the mission operations center there. France and Italy are contributing instruments.

At the heart of every comet lies a remnant of the dawn of the solar system. Or is that remnants? Astronomers don't know, but the answer would give them a clearer picture of exactly how comets were born eons ago at the birth of the Solar System. Did thin tendrils of dust and ice get drawn slowly inward and pack themselves into a single, uniform mass? Or did a hodge-podge of mini-comets come together to form the core for a comet of substance?

For Hartley-2, the answer so far is neither. "We haven't seen a comet like this before," says Michael Mumma of NASA's Goddard Space Flight Center in Greenbelt, Md. "Hartley-2 could be the first of a new breed."

Both data collected by Mumma's team and detailed images of the comet taken by NASA's EPOXI mission reveal that the comet's core is not uniform. "We have evidence of two different kinds of ice in the core, possibly three," says Mumma. "But we can also see that the comet's overall composition is very consistent. So, something subtle is happening. We're not sure what that is."

The researchers observed Hartley-2 six times during the summer, fall and winter of 2010, both before and after the EPOXI mission's Deep Impact spacecraft had its November rendezvous with the comet. Using telescopes perched high in the mountains of Hawaii and Chile, Mumma's team studied the comet's coma—the aura of gas, dust and ice particles that surround the core. The findings of Mumma and his colleagues at Catholic University of America in Washington, D.C., the University of Missouri in St. Louis, the University of Hawaii in Honolulu, the California Institute of Technology in Pasadena, the Max Planck Institute for Solar System Research in Katlenburg-Lindau, Germany, and Rowan University in Glassboro, N.J., are being reported in a special issue of Astrophysical Journal Letters on May 16, 2011

The gases and rocky particles that make up the coma are the clues that astronomers use to deduce what the core is made of, and thus its origin. To see which types of molecules are there, researchers check for telltale signatures in the near-infrared region of light, at wavelengths from 2.9 to 3.8 micrometers. In this way, it's also possible to tell how plentiful each type of molecule is.

Ices in Hartley-2 are mostly made of water, along with traces of many other types of molecules, the team learned. This is in addition to the plentiful carbon dioxide detected in the comet in 1997 by the European Space Agency’s Infrared Space Observatory. Mumma and colleagues paid close attention to the levels of water and seven other molecules that evaporate easily. The molecules remain frozen either on or below the core’s surface until the warming rays of the sun vaporize them; then, they are swept into the coma.

The release of the molecules depends a great deal on exposure to the sun. The researchers knew that in 2009 ground-based observers had detected telltale signs that the core was rotating quickly. So the team was interested in what would happen to the production levels of these molecules as the comet rotated every 18 hours, giving each of its faces a turn to bathe in sunlight. Turns out, they saw something that nobody has seen before.

First of all, they saw the comet's wild side. "The amount of water changed dramatically night by night and even within a single night—in some cases, doubling in that time," says Mumma. But, in truth, Hartley-2 isn't the only comet to get caught being fickle.

What surprised the researchers was this: as the amount of water went up, so did the amounts of the other gases. And as the amount of water went down, the others did, too. "This is the first time anyone has seen an entire suite of these gases change in the same way at the same time," says Mumma.

This result is important for astronomers, he notes, because they often study the gases in a comet's coma one at a time. "But this suggests that if you look at one gas on one night and another the next night, the production rates might change quite a bit. The findings could be different than if you measured the two gases together," he says. "And in the worst case, you could get the wrong idea about the composition of the comet."

Beyond that, Mumma says, "this tells us that the overall composition of the gas in the coma did not change." Taken by itself, this might seem to imply that the core of the comet is uniform. But when the findings of the EPOXI science team are considered, the picture gets more complicated.

"The fact that the gases all vary together is somewhat puzzling, because EPOXI found a large variation in the release of carbon dioxide relative to water," says the head of the EPOXI science team, Michael A'Hearn of the University of Maryland. "At this point the interpretation is pretty speculative."

EPOXI's Deep Impact spacecraft had a rendezvous with the comet in November 2010. The rich images taken then of the comet's surface revealed small, volcano-like "jets" spewing out carbon dioxide gas and water ice at one end. The jets activate when sunlight warms that end of the comet, turning the frozen carbon dioxide (aka dry ice) below the surface into gas that escapes through open holes.

The researchers think that chunks of water ice are glued together in the comet's core by the frozen carbon dioxide, which evaporates before the water ice. "The carbon dioxide gas drags with it chunks of ice, which later evaporate to provide much of the water vapor in the coma," A'Hearn explains.

Researchers had never seen this before. "In other comets that have been visited, most of the water appears to be converted into gas below or at the surface," says A'Hearn. "We have not seen icy grains, or at least, very few, being dragged into the coma."

But the whole core is not made the same way. EPOXI revealed that the carbon dioxide jets are not found at the large end of the comet, and in the middle region, water vapor is released without any carbon dioxide. "So clearly, when we look at the comet up close, the composition of the core changes from one region to another," Mumma says.

Mumma's team found more evidence that Hartley-2's core is not uniform. They did so by looking carefully at four types of gas to see in which directions their molecules traveled after release. They saw that water and another gas, methanol, came off the comet in all directions. "Because they are found together, we infer that they come from the same chunks of ice," he explains.

"So, we have water ice with methanol in it, and we have carbon dioxide ice. Both are in the comet's core," Mumma says. "We may also have a third type of ice, made from ethane."

That possibility is based on the fact that ethane, unlike water and methanol, was released strongly in one direction. "This is actually rather profound," says Mumma. "It suggests that some molecules, such as methanol, may be mixed with water, while others, such as ethane, are not. This isn't the way we've thought of comets, before now."

More research needs to be done, and whether all comets behave like Hartley-2 isn't known, Mumma adds. "But now that we know what this one does, we have a baseline to compare other comets against."

Space shuttle Endeavour is officially on its way to the International Space Station on its STS-134 mission and final flight. Endeavour lifted off from NASA's Kennedy Space Center on time at 8:56 a.m. EDT, soaring through a few clouds, after a relatively smooth countdown.

"I can't thank the teams that got this vehicle ready to fly and for all the work they've done," said Associate Administrator for Space Operations Bill Gerstenmaier referring to the Auxiliary Power Unit (APU) heater issues and said, "The teams worked really hard to get through that, get it behind and to understand what the problem was -- and it was no problem to us at all during the count."

"The teams stayed focused, and made this launch a success," Gerstenmaier added. "The mission in front of us is no easy mission, the EVAs are very demanding - but it'll be exciting to see the AMS get installed on the station and get some real research data for the ISS."

"We showed our determination to succeed on a very complex mission," said Michel Tognini, head of the European Astronaut Center and former ESA astronaut, "and this is the model of human exploration for the future."

Mike Moses apologized (in jest) about the view not being the best and the longest because of the cloud cover." But the data that we were looking at in the launch center was absolutely perfect," said Moses. "We had the clouds where we needed them, so we went."

There were a few minor problems, but they were managed and worked immediately, including the minor tile repair, reported Moses.

After every launch an award is given to one of the teams, according to Shuttle Launch Director Mike Leinbach, and today's honor was given to the combined APU repair/test team. "It was an outstanding countdown, lots of pats on the back in the lobby of the LCC afterwards when we were eating our beans and corn bread ," said Leinbach. "Endeavour's on orbit safely and it's going to perform a great mission and we'll see her back here on June 1."

"It's a great day here at Kennedy Space Center and for the Shuttle Program," added Leinbach.

New data analysis from NASA's Galileo spacecraft reveals a subsurface ocean of molten or partially molten magma beneath the surface of Jupiter's volcanic moon Io.

The finding heralds the first direct confirmation of this kind of magma layer at Io and explains why the moon is the most volcanic object known in the solar system. The research was conducted by scientists at the University of California, Los Angeles; the University of California, Santa Cruz;, and the University of Michigan, Ann Arbor. The study is published this week in the journal Science.

"Scientists are excited we finally understand where Io's magma is coming from and have an explanation for some of the mysterious signatures we saw in some of the Galileo's magnetic field data," said Krishan Khurana, lead author of the study and former co-investigator on Galileo's magnetometer team at UCLA. "It turns out Io was continually giving off a 'sounding signal' in Jupiter's rotating magnetic field that matched what would be expected from molten or partially molten rocks deep beneath the surface."

Io produces about 100 times more lava each year than all the volcanoes on Earth. While Earth's volcanoes occur in localized hotspots like the "Ring of Fire" around the Pacific Ocean, Io's volcanoes are distributed all over its surface. A global magma ocean about 30 to 50 kilometers (20 to 30 miles) beneath Io's crust helps explain the moon's activity.

"It has been suggested that both the Earth and its moon may have had similar magma oceans billions of years ago at the time of their formation, but they have long since cooled," said Torrence Johnson, a former Galileo project scientist based at NASA's Jet Propulsion Laboratory in Pasadena, Calif. He was not directly involved in the study. "Io's volcanism informs us how volcanoes work and provides a window in time to styles of volcanic activity that may have occurred on the Earth and moon during their earliest history."

NASA's Voyager spacecraft discovered Io's volcanoes in 1979, making that moon the only body in the solar system other than Earth known to have active magma volcanoes. The energy for the volcanic activity comes from the squeezing and stretching of the moon by Jupiter's gravity as Io orbits the largest planet in the solar system.

Galileo was launched in 1989 and began orbiting Jupiter in 1995. Unexplained signatures appeared in magnetic field data from Galileo flybys of Io in October 1999 and February 2000. After a successful mission, the spacecraft was intentionally sent into Jupiter's atmosphere in 2003.

"During the final phase of the Galileo mission, models of the interaction between Io and Jupiter's immense magnetic field, which bathes the moon in charged particles, were not yet sophisticated enough for us to understand what was going on in Io's interior," said Xianzhe Jia, a co-author of the study at the University of Michigan.

Recent work in mineral physics showed that a group of rocks known as "ultramafic" rocks become capable of carrying substantial electrical current when melted. Ultramafic rocks are igneous in origin, or form through the cooling of magma. On Earth, they are believed to originate from the mantle. The finding led Khurana and colleagues to test the hypothesis that the strange signature was produced by current flowing in a molten or partially molten layer of this kind of rock.

Tests showed that the signatures detected by Galileo were consistent with a rock such as lherzolite, an igneous rock rich in silicates of magnesium and iron found in Spitzbergen, Norway. The magma ocean layer on Io appears to be more than 50 kilometers (30 miles thick), making up at least 10 percent of the moon's mantle by volume. The blistering temperature of the magma ocean probably exceeds 1,200 degrees Celsius.

The Galileo mission was managed by JPL for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.

The famous Crab Nebula supernova remnant has erupted in an enormous flare five times more powerful than any flare previously seen from the object. On April 12, NASA's Fermi Gamma-ray Space Telescope first detected the outburst, which lasted six days.

The nebula is the wreckage of an exploded star that emitted light which reached Earth in the year 1054. It is located 6,500 light-years away in the constellation Taurus. At the heart of an expanding gas cloud lies what is left of the original star's core, a superdense neutron star that spins 30 times a second. With each rotation, the star swings intense beams of radiation toward Earth, creating the pulsed emission characteristic of spinning neutron stars.

Apart from these pulses, astrophysicists believed the Crab Nebula was a virtually constant source of high-energy radiation. But in January, scientists associated with several orbiting observatories, including NASA's Fermi, Swift and Rossi X-ray Timing Explorer, reported long-term brightness changes at X-ray energies.

"The Crab Nebula hosts high-energy variability that we're only now fully appreciating," said Rolf Buehler, a member of the Fermi Large Area Telescope (LAT) team at the Kavli Institute for Particle Astrophysics and Cosmology, a facility jointly located at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University.

Since 2009, Fermi and the Italian Space Agency's AGILE satellite have detected several short-lived gamma-ray flares at energies greater than 100 million electron volts (eV) -- hundreds of times higher than the nebula's observed X-ray variations. For comparison, visible light has energies between 2 and 3 eV.

On April 12, Fermi's LAT, and later AGILE, detected a flare that grew about 30 times more energetic than the nebula's normal gamma-ray output and about five times more powerful than previous outbursts. On April 16, an even brighter flare erupted, but within a couple of days, the unusual activity completely faded out.

"These superflares are the most intense outbursts we've seen to date, and they are all extremely puzzling events," said Alice Harding at NASA's Goddard Space Flight Center in Greenbelt, Md. "We think they are caused by sudden rearrangements of the magnetic field not far from the neutron star, but exactly where that's happening remains a mystery."

The Crab's high-energy emissions are thought to be the result of physical processes that tap into the neutron star's rapid spin. Theorists generally agree the flares must arise within about one-third of a light-year from the neutron star, but efforts to locate them more precisely have proven unsuccessful so far.

Since September 2010, NASA's Chandra X-ray Observatory routinely has monitored the nebula in an effort to identify X-ray emission associated with the outbursts. When Fermi scientists alerted astronomers to the onset of a new flare, Martin Weisskopf and Allyn Tennant at NASA's Marshall Space Flight Center in Huntsville, Ala., triggered a set of pre-planned observations using Chandra.

"Thanks to the Fermi alert, we were fortunate that our planned observations actually occurred when the flares were brightest in gamma rays," Weisskopf said. "Despite Chandra's excellent resolution, we detected no obvious changes in the X-ray structures in the nebula and surrounding the pulsar that could be clearly associated with the flare."

Scientists think the flares occur as the intense magnetic field near the pulsar undergoes sudden restructuring. Such changes can accelerate particles like electrons to velocities near the speed of light. As these high-speed electrons interact with the magnetic field, they emit gamma rays.

To account for the observed emission, scientists say the electrons must have energies 100 times greater than can be achieved in any particle accelerator on Earth. This makes them the highest-energy electrons known to be associated with any cosmic source. Based on the rise and fall of gamma rays during the April outbursts, scientists estimate that the size of the emitting region must be comparable in size to the solar system.

NASA's Fermi is an astrophysics and particle physics partnership managed by NASA's Goddard Space Flight Center in Greenbelt, Md., and developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

The Marshall Space Flight Center 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.

How do instruments end up on satellites orbiting the Earth?

For many of them, long before they are ever launched into space, they are tested from NASA airplanes. One of the objectives of the NASA Airborne Science Program is to test new instruments in space-like environments. Testing future satellite instruments from airplanes is the next best thing to actually testing them in space.

Over the past three weeks, a team from NASA's Goddard Space Flight Center, Greenbelt, Md., led by Bill Heaps has been testing a new broadband lidar instrument on NASA’s DC-8 flying laboratory that they hope will fly on the ASCENDS satellite mission. ASCENDS, an acronym for Active Sensing of Carbon dioxide Emissions over Nights, Days and Seasons, is an upcoming NASA satellite expected to be launched in 2018-2020. The goal of the ASCENDS mission is to measure the sources, distribution and variations in carbon dioxide gas with very high precision all over the Earth. Mapping carbon dioxide is important for understanding the global carbon cycle and for modeling global climate change.

How is carbon dioxide measured from space?

Carbon dioxide makes up a very small fraction of the gas in Earth’s atmosphere. In addition, the majority of the carbon dioxide variability occurs in the first 100 feet above the surface of the Earth. In order to measure the abundance of carbon dioxide from a satellite, any instrument must therefore look through Earth’s entire atmosphere in order to detect the variations in carbon dioxide occurring near the surface.

Heaps’ broadband lidar – an acronym for light detection and ranging -- uses an infrared laser beam aimed at the surface of the Earth. As the laser passes through the atmosphere and bounces off the ground, carbon dioxide molecules in the atmosphere absorb some of the light from the laser. Measuring the amount of absorption that occurs as the instrument passes over different locations on the Earth will allow the team to build global carbon dioxide maps.

Typical lidar systems have lasers that emit light at very specific colors, or wavelengths. The carbon dioxide molecule, however, absorbs light at a several different infrared wavelengths. The broadband laser used in Heaps’ instrument emits light with a broader range of wavelengths, and thus has the advantage of being able to detect carbon dioxide absorption in multiple wavelength bands with one laser. The wavelength control requirements are also less strict than for a more conventional narrowband laser, which may make the system easier to implement on a satellite.

The Goddard team worked for over two weeks to install and test their instrument in the belly of the DC-8 at the NASA Dryden Aircraft Operations Facility in Palmdale, Calif.

The team then flew with their instrument on two four-hour flights on the converted jetliner during the week of May 2 – 6 over northern and central California. During the flights, they tested the instrument’s performance at variety of altitudes and over different types of surfaces – deserts, agricultural fields, mountainous terrain, the ocean and the flat waters of Lake Tahoe. The team was very pleased with the performance of the instrument.

Bill Heaps tests the broadband lidar instrument inside lower fuselage of NASA's DC-8 flying laboratory.Bill Heaps tests the broadband lidar instrument inside lower fuselage of NASA's DC-8 flying laboratory. (Elena Georgieva)
› View Larger Image “The system definitely measured CO2 on both flights, even transmitting a very small amount of laser power. I believe the broadband technique has excellent potential to be scaled up for measurements from space,” Heaps said.

This July, several instrument teams, all vying to have their instrument fly on ASCENDS, will test their instruments side-by-side on the DC-8. With data from the test flights of the broadband lidar instrument in hand, Heaps’ team will return to Goddard to make refinements and improvements in the hope that their instrument will be chosen to fly on the ASCENDS satellite mission.

The NASA Earth Science Technology Office Instrument Incubator program provided funding for the Goddard broadband lidar.

One of the space shuttle program's earliest commanders and the first woman to live on the International Space Station took their places alongside the nation's space heroes May 7 as they were welcomed into the U.S. Astronaut Hall of Fame.

Karol "Bo" Bobko and Susan Helms joined the Hall of Fame during a ceremony at the Kennedy Space Center Visitor Complex at NASA's Kennedy Space Center in Florida. The celebration came two days after NASA marked the 50th anniversary of Alan Shepard's flight in 1961 that made him the first American in space.

Bobko flew as the pilot on STS-6, the first flight of space shuttle Challenger, in April 1983. Two years later, he commanded Discovery on STS-51D and landed the shuttle safely despite a blown main gear tire. Six months later, Bobko commanded Atlantis on its maiden flight, STS-51J.

"My wife said whenever I was given a chance, I chose the career path toward space," Bobko said. "All spaceflight is beautiful and inspiring."

The astronaut thought he would go into space a lot sooner. The Air Force chose him for its own astronaut corps in 1966 to crew the Manned Orbiting Laboratory, or MOL, a project the Air Force later canceled. Like STS-1 Pilot Bob Crippen and five others who were in the MOL program, Bobko joined NASA. He worked on the Apollo-Soyuz Test Project as a support team member before flying as a chase pilot on the shuttle prototype Enterprise landing tests.

"Bo loved spaceflight and he wanted everyone working with him to enjoy it as much as he did," said Bobko's presenter, former astronaut Jeff Hoffman. "He enjoyed flying so much that his family said they could judge how close he was getting to a flight because the smile on his face kept getting bigger and bigger and bigger."

Helms, an Air Force veteran like Bobko, flew five times on the shuttle beginning with STS-54 in January 1993. Her spaceflight career included flights on Endeavour, Discovery, Columbia, Atlantis and the International Space Station. She spent more than 5,000 hours in space, with 163 days of that on the station.

"It was one of the most amazing things that I've ever had the chance to do, which was be part of a space outpost" Helms said. "That truly was a human adventure that has no equal."

Working from Discovery, Helms performed a world-record spacewalk lasting eight hours and 56 minutes.

Endurance was kind of a trademark of Helms, said her presenter, NASA Administrator and former astronaut Charlie Bolden. She went for a jog on one occasion with her dog, Radar, and when she and the dog got back, she said the jog had gone fine. But Radar went and laid down on the bed for two days.

On the morning of May 5, 1961, astronaut Alan Shepard crawled into the cramped Mercury capsule, "Freedom 7," at Launch Complex 5 at Florida's Cape Canaveral Air Force Station. The slender, 82-foot-tall Mercury-Redstone rocket rose from the launch pad at 9:34 a.m. EST, sending Shepard on a remarkably successful, 15-minute suborbital flight.

But more than that, it kick-started America's future as a spacefaring nation.

On the 50th anniversary of Shepard's pioneering flight, his three daughters, Laura Churchley, Julie Jenkins and Alice Wackermann, joined former space workers and their families, community leaders and others to celebrate the flight and its legacy.

"In the audience today, we have more than 100 workers from the Mercury era who devoted their lives to flying humans safely in space," said Kennedy Space Center Director Bob Cabana. He asked them to stand, and they were greeted by a round of applause.

"You should be extremely proud of what you did for our country and for humankind," Cabana said.

The flight of "Freedom 7" boosted spirits throughout the country at a time when the U.S. appeared to be faltering in the quest for a viable space program. Just weeks before, on April 12, 1961, Russian cosmonaut Yuri Gagarin had become the first human in space, orbiting the Earth for 108 minutes in the Vostok 1 spacecraft.

A U.S. Navy test pilot, Shepard was one of the first astronauts selected by NASA. The "Mercury Seven" astronauts -- M. Scott Carpenter, Leroy Gordon Cooper, Shepard, John H. Glenn Jr., Virgil I. "Gus" Grissom Jr., Walter M. "Wally" Schirra Jr., and Donald K. "Deke" Slayton -- were introduced to the nation in April 1959. NASA kept the identity of the first astronaut to fly a secret until word of Shepard's command got out just days before the launch.

After ignition, Shepard reached up to start the mission clock. The vehicle experienced some vibration about a minute and a half into flight when it pierced the area of peak aerodynamic pressure, but Shepard enjoyed a smoother ride as the Redstone pushed skyward. Once the Mercury spacecraft separated from the rocket, the capsule turned, with its heat shield facing forward. During the short flight, Shepard took in the amazing view and experimented with the spacecraft's controls.

At the anniversary event, the entire flight was replayed in a video that began five minutes before launch time, with liftoff and landing at the precise moment when Shepard began and ended his mission 50 years ago.

"It was an intense countdown. Everybody had their job. There was no joking around," said Former Chief Test Conductor Bob Moser. "But we enjoyed it, and it worked. Congratulations to all of us. We were a great team."

The flight was significant not only because it displayed bravery and technological progress, but also because it played out before journalists and the public. For the first time, the world was able to share in the tension and excitement as the historic event unfolded on television in real time.

"To me -- and I've gone through hundreds of launches and done countdowns in hundreds of launches -- the first is always very special," said Jack King, former chief of NASA's Public Information Office. "I must admit, it's the only one when I was misty-eyed. The first American in space! I couldn't be prouder. And I couldn't be prouder for being a part of it."

"Freedom 7" was only the beginning of Shepard's spaceflight career. He went on to serve as chief of the Astronaut Office after his first flight. In 1971, he commanded the Apollo 14 mission, landing along with Lunar Module Pilot Edgar Mitchell in the Fra Mauro region originally intended as Apollo 13's target while Command Module Pilot Stuart Roosa orbited overhead.

"I remember every time he spoke, he always gave credit to everyone in NASA who built the good ships that brought him home to us safely," Churchley said. "We thank you all very much."

Human spaceflight has changed dramatically in the ensuing half-century. A space shuttle flight is typically about two weeks; long-duration increments aboard the massive International Space Station last several months. Today's space missions are intricate and complex, requiring years of training and rehearsal, with crews of five, six or seven astronauts working together on a single flight. Rather than a race to the finish, a spirit of international cooperation provides a backdrop for today's space program.

NASA's Gravity Probe B (GP-B) mission has confirmed two key predictions derived from Albert Einstein's general theory of relativity, which the spacecraft was designed to test.

The experiment, launched in 2004, used four ultra-precise gyroscopes to measure the hypothesized geodetic effect, the warping of space and time around a gravitational body, and frame-dragging, the amount a spinning object pulls space and time with it as it rotates.

GP-B determined both effects with unprecedented precision by pointing at a single star, IM Pegasi, while in a polar orbit around Earth. If gravity did not affect space and time, GP-B's gyroscopes would point in the same direction forever while in orbit. But in confirmation of Einstein's theories, the gyroscopes experienced measurable, minute changes in the direction of their spin, while Earth's gravity pulled at them.

The findings are online in the journal Physical Review Letters.

"Imagine the Earth as if it were immersed in honey. As the planet rotates, the honey around it would swirl, and it's the same with space and time," said Francis Everitt, GP-B principal investigator at Stanford University. "GP-B confirmed two of the most profound predictions of Einstein's universe, having far-reaching implications across astrophysics research. Likewise, the decades of technological innovation behind the mission will have a lasting legacy on Earth and in space."

GP-B is one of the longest running projects in NASA history, with agency involvement starting in the fall of 1963 with initial funding to develop a relativity gyroscope experiment. Subsequent decades of development led to groundbreaking technologies to control environmental disturbances on spacecraft, such as aerodynamic drag, magnetic fields and thermal variations. The mission's star tracker and gyroscopes were the most precise ever designed and produced.

GP-B completed its data collection operations and was decommissioned in December 2010.

"The mission results will have a long-term impact on the work of theoretical physicists," said Bill Danchi, senior astrophysicist and program scientist at NASA Headquarters in Washington. "Every future challenge to Einstein's theories of general relativity will have to seek more precise measurements than the remarkable work GP-B accomplished."

Innovations enabled by GP-B have been used in GPS technologies that allow airplanes to land unaided. Additional GP-B technologies were applied to NASA's Cosmic Background Explorer mission, which accurately determined the universe's background radiation. That measurement is the underpinning of the big-bang theory, and led to the Nobel Prize for NASA physicist John Mather.

The drag-free satellite concept pioneered by GP-B made a number of Earth-observing satellites possible, including NASA's Gravity Recovery and Climate Experiment and the European Space Agency's Gravity field and steady-state Ocean Circulation Explorer. These satellites provide the most precise measurements of the shape of the Earth, critical for precise navigation on land and sea, and understanding the relationship between ocean circulation and climate patterns.

GP-B also advanced the frontiers of knowledge and provided a practical training ground for 100 doctoral students and 15 master's degree candidates at universities across the United States. More than 350 undergraduates and more than four dozen high school students also worked on the project with leading scientists and aerospace engineers from industry and government. One undergraduate student who worked on GP-B became the first American woman in space, Sally Ride. Another was Eric Cornell who won the Nobel Prize in Physics in 2001.

"GP-B adds to the knowledge base on relativity in important ways and its positive impact will be felt in the careers of students whose educations were enriched by the project," said Ed Weiler, associate administrator for the Science Mission Directorate at NASA Headquarters.

NASA's Marshall Space Flight Center in Huntsville, Ala., managed the Gravity Probe-B program for the agency. Stanford University, NASA's prime contractor for the mission, conceived the experiment and was responsible for the design and integration of the science instrument, mission operations and data analysis. Lockheed Martin Corp. of Huntsville designed, integrated and tested the space vehicle and some of its major payload components.

NASA's Dawn spacecraft has reached its official approach phase to the asteroid Vesta and will begin using cameras for the first time to aid navigation for an expected July 16 orbital encounter. The large asteroid is known as a protoplanet – a celestial body that almost formed into a planet.

At the start of this three-month final approach to this massive body in the asteroid belt, Dawn is 1.21 million kilometers (752,000 miles) from Vesta, or about three times the distance between Earth and the moon. During the approach phase, the spacecraft's main activity will be thrusting with a special, hyper-efficient ion engine that uses electricity to ionize and accelerate xenon. The 12-inch-wide ion thrusters provide less thrust than conventional engines, but will provide propulsion for years during the mission and provide far greater capability to change velocity.

"We feel a little like Columbus approaching the shores of the New World," said Christopher Russell, Dawn principal investigator, based at the University of California in Los Angeles (UCLA). "The Dawn team can't wait to start mapping this Terra Incognita."

Dawn previously navigated by measuring the radio signal between the spacecraft and Earth, and used other methods that did not involve Vesta. But as the spacecraft closes in on its target, navigation requires more precise measurements. By analyzing where Vesta appears relative to stars, navigators will pin down its location and enable engineers to refine the spacecraft's trajectory. Using its ion engine to match Vesta's orbit around the sun, the spacecraft will spiral gently into orbit around the asteroid. When Dawn gets approximately 16,000 kilometers (9,900 miles) from Vesta, the asteroid's gravity will capture the spacecraft in orbit.

"After more than three-and-a-half years of interplanetary travel, we are finally closing in on our first destination," said Marc Rayman, Dawn's chief engineer, at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We're not there yet, but Dawn will soon bring into focus an entire world that has been, for most of the two centuries scientists have been studying it, little more than a pinpoint of light."

Scientists will search the framing camera images for possible moons around Vesta. None of the images from ground-based and Earth-orbiting telescopes have seen any moons, but Dawn will give scientists much more detailed images to determine whether small objects have gone undiscovered.

The gamma ray and neutron detector instrument also will gather information on cosmic rays during the approach phase, providing a baseline for comparison when Dawn is much closer to Vesta. Simultaneously, Dawn's visible and infrared mapping spectrometer will take early measurements to ensure it is calibrated and ready when the spacecraft enters orbit around Vesta.

Dawn's odyssey, which will take it on a journey of 4.8-billion kilometers (3-billion miles), began on Sept. 27, 2007, with its launch from Cape Canaveral Air Force Station in Florida. It will stay in orbit around Vesta for one year. After another long cruise phase, Dawn will arrive at its second destination, an even more massive body in the asteroid belt, called Ceres, in 2015.

These two icons of the asteroid belt will help scientists unlock the secrets of our solar system's early history. The mission will compare and contrast the two giant bodies, which were shaped by different forces. Dawn's science instrument suite will measure surface composition, topography and texture. In addition, the Dawn spacecraft will measure the tug of gravity from Vesta and Ceres to learn more about their internal structures.

The Dawn mission to Vesta and Ceres is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of SMD's Discovery Program, which is 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 Dawn spacecraft. The framing cameras have been developed and built under the leadership of the Max Planck Institute for Solar System Research in Katlenburg-Lindau in Germany, with significant contributions by the German Aerospace Center (DLR) Institute of Planetary Research in Berlin, and in coordination with the Institute of Computer and Communication Network Engineering in Braunschweig. The framing camera project is funded by NASA, the Max Planck Society and DLR.

NASA Administrator Charles Bolden will commemorate the 50th anniversary of the first U.S. manned spaceflight during two events this week around the agency's Kennedy Space Center in Florida. NASA Television will carry both events live.

On Wednesday, May 4, at 2 p.m. EDT, the U.S. Postal Service will unveil two new stamps at the Rocket Garden of the Kennedy Space Center Visitor Complex, located on State Road 405. Journalists interested in covering the event should contact Andrea Farmer at 321-449-4318 or Jillian McRae at 321-449-4273. Media need to arrive at least 30 minutes before the start of the ceremony.

One stamp commemorates NASA's Project Mercury and Alan Shepard's historic launch on May 5, 1961 aboard the spacecraft Freedom 7. The second stamp honors NASA's MESSENGER, which reached Mercury in March to become the first spacecraft to orbit the planet. The two missions frame a remarkable 50-year period in which America advanced space exploration through more than 1,500 manned and unmanned flights.

Mercury astronaut Scott Carpenter and members of the Shepard family will join Bolden at the stamps' unveiling and at a 50th anniversary ceremony on Thursday, May 5, at 9 a.m., at the Cape Canaveral Air Force Station.
To cover the event, news media representatives need to be at the Air Force Badging Office at 6:30 a.m. for transportation to Complex 5/6. Mission badges for the STS-134 shuttle mission will be honored for this event. Reporters who do not have one must contact Christopher Calkins at 321-494-7732 or Auburn Davis at 321-494-6489 to arrange for media credentials.

The Thursday event includes a re-creation of Shepard's flight and recovery, as well as a tribute to his contributions as a moonwalker on the Apollo 14 lunar mission. KSC Director and former astronaut Bob Cabana and more than 200 workers from the original Mercury program, also will be in attendance.

NASA managers have determined space shuttle Endeavour will not launch before Sunday, May 8, but will not officially set a new launch date until early this week.


After Friday’s launch scrub, Kennedy Space Center technicians searched for the cause of a failure in a heater circuit associated with Endeavour’s hydraulic power system. The failure was found to be in a power circuit in a switchbox in the shuttle’s aft compartment.

Managers and engineers are developing a schedule to remove and replace the switchbox and retest the new unit. That work will delay Endeavour’s launch until at least May 8.


The shuttle has three Auxiliary Power Units that provide hydraulic power to steer the vehicle during ascent and entry. The hydrazine fuel lines on each APU have two heater circuits that prevent the fuel from freezing while the shuttle is in space. NASA launch commit criteria and flight rules require all three APUs and heater circuits to be operational for liftoff.