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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 March 2011

NASA has signed a $36.9 million contract modification to space shuttle main engine manufacturer Pratt & Whitney Rocketdyne of Canoga Park, Calif., to provide continued shuttle main engine prelaunch and launch support from April 1 through July 31.

The contract modification also provides two additional options that if exercised, would bring the potential contract amount for all six months to $56 million.

This modification supports the flyout of the Space Shuttle Program and brings the total potential value of the contract to $2.29 billion. The original contract began on Jan. 1, 2002.

The majority of the work will take place at Pratt & Whitney Rocketdyne's headquarters in Canoga Park.

Three main engines and two solid rocket boosters provide the thrust to launch the space shuttle. At 14-feet long and seven-and-a-half feet in diameter at the nozzle exit, the liquid propellant main engines have a combined thrust of more than 1.2 million pounds.

Scientists recently completed a series of nighttime, ground-based testing of the German Receiver for Astronomy at Terahertz Frequencies, or GREAT, spectrometer in preparation for a series of astronomical science flights on the Stratospheric Observatory for Infrared Astronomy in April. With the SOFIA 747SP aircraft positioned on the ramp outside NASA’s Dryden Aircraft Operations Facility, the upper door covering the telescope was opened and GREAT’s interaction with the telescope was evaluated.

The GREAT instrument is a receiver for spectroscopic observations at far-infrared frequencies between 1.2 and 5 terahertz (wavelengths between 60 and 250 microns). Those wavelengths are not accessible from ground-based telescopes because of atmospheric water vapor absorption.

GREAT is one of two first-generation instruments built for SOFIA by a consortium of German research institutes, including the Max Planck Institute for Radio Astronomy, the University of Cologne, the German Aerospace Center and the Max Planck Society. The Max Planck Society and German Research Society financed the development of the instrument.

SOFIA is a joint venture of NASA and the German Aerospace Center DLR. NASA supplied the aircraft and the telescope was built in Germany. NASA’s Dryden Flight Research Center manages the SOFIA program. NASA's Ames Research Center at Moffett Field, Calif., manages SOFIA's scientific mission. The Universities Space Research Association, in Columbia, Md., and the German SOFIA Institute in Stuttgart, Germany, operate SOFIA's scientific mission operations respectively for NASA and the DLR.

NASA has selected five potential discoverers as the recipients of the 2011 Carl Sagan Postdoctoral Fellowships, named after the late astronomer. The Carl Sagan Fellowship takes a theme-based approach, in which fellows will focus on compelling scientific questions, such as "Are there Earth-like planets orbiting other stars?"

Sagan once said, "Somewhere, something incredible is waiting to be known," which is in line with the Sagan Fellowship's primary goal: to discover and characterize planetary systems and Earth-like planets around other stars. Planets outside of our solar system are called exoplanets. The fellowship also aims to support outstanding recent postdoctoral scientists in conducting independent research broadly related to the science goals of NASA's Exoplanet Exploration Program.

Previous Sagan Fellows have contributed significant discoveries in exoplanet exploration. including: the first characterizations of a super-Earth's atmosphere using a ground-based telescope; and the discovery of a massive disk of dust and gas encircling a giant young star, which could potentially answer the long-standing question of how massive stars are born.

"The Sagan Fellowship program seeks to identify the most highly qualified young researchers in the field of exoplanets. Nowhere is the dynamism of this young branch of astronomy demonstrated more dramatically than by the intellectual quality and enthusiasm of these five new Sagan Fellows," said Charles Beichman, executive director of the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena. "These scientists are certain to be leaders of this exciting and rapidly growing field for many years to come."

The program, created in 2008, awards selected postdoctoral scientists with annual stipends of approximately $64,500 for up to three years, plus an annual research budget of up to $16,000. Topics range from techniques for detecting the glow of a dim planet in the blinding glare of its host star, to searching for the crucial ingredients of life in other planetary systems.

NASA's Stardust spacecraft sent its last transmission to Earth at 4:33 p.m. PDT (7:33 p.m. EDT) Thursday, March 24, shortly after depleting fuel and ceasing operations. During a 12-year period, the venerable spacecraft collected and returned comet material to Earth and was reused after the end of its prime mission in 2006 to observe and study another comet during February 2011.

The Stardust team performed the burn to depletion because the comet hunter was literally running on fumes. The depletion maneuver command was sent from the Stardust-NExT mission control area at Lockheed Martin Space Systems in Denver. The operation was designed to fire Stardust's rockets until no fuel remained in the tank or fuel lines. The spacecraft sent acknowledgment of its last command from approximately 312 million kilometers (194 million miles) away in space.

"This is the end of the spacecraft's operations, but really just the beginnings of what this spacecraft's accomplishments will give to planetary science," said Lindley Johnson, Stardust-NExT and Discovery program executive at NASA Headquarters in Washington. "The treasure-trove of science data and engineering information collected and returned by Stardust is invaluable for planning future deep space planetary missions."

After completion of the burn, mission personnel began comparing the computed amount of fuel consumed during the engine firing with the anticipated amount based on consumption models. The models are required to track fuel levels, because there are no fully reliable fuel gauges for spacecraft in the weightless environment of space. Mission planners use approximate fuel usage by reviewing the history of the vehicle's flight, how many times and how long its rocket motors fired.

"Stardust's motors burned for 146 seconds," said Allan Cheuvront, Lockheed Martin Space Systems Company program manager for Stardust-NExT in Denver. "We'll crunch the numbers and see how close the reality matches up with our projections. That will be a great data set to have in our back pocket when we plan for future missions."

Launched Feb. 7, 1999, Stardust flew past the asteroid named Annefrank and traveled halfway to Jupiter to collect the particle samples from the comet Wild 2. The spacecraft returned to Earth's vicinity to drop off a sample return capsule eagerly awaited by comet scientists.

NASA re-tasked the spacecraft as Stardust-NExT to perform a bonus mission and fly past comet Tempel 1, which was struck by the Deep Impact mission in 2005. The mission collected images and other scientific data to compare with images of that comet collected by the Deep Impact mission in 2005. Stardust traveled approximately 21 million kilometers (13 million miles) around the sun in the weeks after the successful Tempel 1 flyby. The Stardust-NExT mission met all mission goals, and the spacecraft was extremely successful during both missions. From launch until final rocket engine burn, Stardust travelled approximately 5.69 billion kilometers (3.54 billion miles).

After the mileage logged in space, the Stardust team knew the end was near for the spacecraft. With its fuel tank empty and final radio transmission concluded, history's most traveled comet hunter will move from NASA's active mission roster to retired.

"This kind of feels like the end of one of those old western movies where you watch the hero ride his horse towards the distant setting sun -- and then the credits begin to roll," said Stardust-NExT project manager Tim Larson from NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Only there's no setting sun in space."

Stardust and Stardust-NExT missions were managed by JPL for NASA's Science Mission Directorate in Washington. The missions were part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Joe Veverka of Cornell University was the Stardust-NExT principal investigator. Don Brownlee of the University of Washington in Seattle was the Stardust principal investigator. Lockheed Martin Space Systems built the spacecraft and managed day-to-day mission operations.





 At 33 minutes after 4 p.m. PDT today, NASA's Stardust spacecraft finished its last transmission to Earth. The transmission came on the heels of the venerable spacecraft's final rocket burn, which was designed to provide insight into how much fuel remained aboard after its encounter with comet Tempel 1 in February.
"Stardust has been teaching us about our solar system since it was launched in 1999," said Stardust-NExT project manager Tim Larson from NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It makes sense that its very last moments would be providing us with data we can use to plan deep space mission operations in the future."

The burn to depletion maneuver was designed to fire Stardust's rockets until insufficient fuel remains to continue, all the while downlinking data on the burn to Earth some 312 million kilometers (194 million miles) away. Mission personnel will compare the amount of fuel consumed in the burn with the amount they anticipated would be burned based on their fuel consumption models.

Fuel consumption models are necessary because no one has invented a reliable fuel gauge for spacecraft when in the weightless environment of space flight. Until that day arrives, mission planners can approximate fuel usage by looking at the history of the vehicle's flight and how many times and for how long its rocket motors have fired.

Mission personnel watched the final data from the burn come down at JPL's Space Flight Operations Facility and at the Stardust-NExT mission support center at Lockheed Martin Space Systems in Denver.
"Stardust motors burned for 146 seconds," said Allan Cheuvront, Lockheed Martin Space Systems Company program manager for Stardust-NExT. "We'll crunch the numbers and see how close the reality matches up with our projections. That will be a great data set to have in our back pocket when we plan for future missions."

The Stardust team performed the final burn to depletion because NASA's most senior comet hunter is a spacecraft literally running on fumes. Launched on Feb. 7, 1999, Stardust had completed its prime mission back in January 2006. By that time, Stardust had already flown past an asteroid (Annefrank), flown halfway out to Jupiter to collect particle samples from the coma of a comet, Wild 2, and returned to fly by Earth to drop off a sample return capsule eagerly awaited by comet scientists. NASA then re-tasked the spacecraft to perform a bonus mission to fly past comet Tempel 1 to collect images and other scientific data. Stardust has traveled about 21 million kilometers (13 million miles) in its journey about the sun in the few weeks since the Valentine's day comet Tempel 1 flyby, making the grand total from launch to its final rocket burn about 5.69 billion kilometers.

With all that mileage logged, the Stardust team knew the end was near. Now, with its fuel tank empty and its final messages transmitted, history's most traveled comet hunter will move from NASA's active mission roster to retired.

"This kind of feels like the end of one of those old Western movies where you watch the hero ride his horse towards the distant setting sun – and then the credits begin to roll," said Larson. "Only there's no setting sun in space."

Stardust-NExT was a low-cost mission to expand the investigation of comet Tempel 1 initiated by NASA's Deep Impact spacecraft. JPL, a division of the California Institute of Technology in Pasadena, managed the Stardust-NExT project for the NASA Science Mission Directorate, Washington, D.C., which was part of the Discovery Program managed by NASA's Marshall Space Flight Center in Huntsville, Ala. Joe Veverka of Cornell University, Ithaca, N.Y., was the mission's principal investigator. Lockheed Martin Space Systems, Denver, built the spacecraft and managed day-to-day mission operations.

X-ray observations made by the Suzaku observatory provide the clearest picture to date of the size, mass and chemical content of a nearby cluster of galaxies. The study also provides the first direct evidence that million-degree gas clouds are tightly gathered in the cluster's outskirts.
Suzaku is sponsored by the Japan Aerospace Exploration Agency (JAXA) with contributions from NASA and participation by the international scientific community. The findings will appear in the March 25 issue of the journal Science.

Galaxy clusters are millions of light-years across, and most of their normal matter comes in the form of hot X-ray-emitting gas that fills the space between the galaxies.

"Understanding the content of normal matter in galaxy clusters is a key element for using these objects to study the evolution of the universe," explained Adam Mantz, a co-author of the paper at NASA's Goddard Space Flight Center in Greenbelt, Md.

Clusters provide independent checks on cosmological values established by other means, such as galaxy surveys, exploding stars and the cosmic microwave background, which is the remnant glow of the Big Bang. The cluster data and the other values didn't agree.

NASA's Wilkinson Microwave Anisotropy Probe (WMAP) explored the cosmic microwave background and established that baryons -- what physicists call normal matter -- make up only about 4.6 percent of the universe. Yet previous studies showed that galaxy clusters seemed to hold even fewer baryons than this amount.

Suzaku images of faint gas at the fringes of a nearby galaxy cluster have allowed astronomers to resolve this discrepancy for the first time.

The satellite's ideal target for this study was the Perseus Galaxy Cluster, which is located about 250 million light-years away and named for the constellation in which it resides. It is the brightest extended X-ray source beyond our own galaxy, and also the brightest and closest cluster in which Suzaku has attempted to map outlying gas.

"Before Suzaku, our knowledge of the properties of this gas was limited to the innermost parts of clusters, where the X-ray emission is brightest, but this left a huge volume essentially unexplored," said Aurora Simionescu, the study's lead researcher at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University.

In late 2009, Suzaku's X-ray telescopes repeatedly observed the cluster by progressively imaging areas farther east and northwest of the center. Each set of images probed sky regions two degrees across -- equivalent to four times the apparent width of the full moon or about 9 million light-years at the cluster's distance. Staring at the cluster for about three days, the satellite mapped X-rays with energies hundreds of times greater than that of visible light.

From the data, researchers measured the density and temperature of the faint X-ray gas, which let them infer many other important quantities. One is the so-called virial radius, which essentially marks the edge of the cluster. Based on this measurement, the cluster is 11.6 million light-years across and contains more than 660 trillion times the mass of the sun. That's nearly a thousand times the mass of our Milky Way galaxy.

The researchers also determined the ratio of the cluster's gas mass to its total mass, including dark matter -- the mysterious substance that makes up about 23 percent of the universe, according to WMAP. By virtue of their enormous size, galaxy clusters should contain a representative sample of cosmic matter, with normal-to-dark-matter ratios similar to WMAP's. Yet the outer parts of the Perseus cluster seemed to contain too many baryons, the opposite of earlier studies, but still in conflict with WMAP.

To solve the problem, researchers had to understand the distribution of hot gas in the cluster, the researchers say. In the central regions, the gas is repeatedly whipped up and smoothed out by passing galaxies. But computer simulations show that fresh infalling gas at the cluster edge tends to form irregular clumps.

Not accounting for the clumping overestimates the density of the gas. This is what led to the apparent disagreement with the fraction of normal matter found in the cosmic microwave background.

"The distribution of these clumps and the fact that they are not immediately destroyed as they enter the cluster are important clues in understanding the physical processes that take place in these previously unexplored regions," said Steve Allen at KIPAC, the principal investigator of the Suzaku observations.

Goddard supplied Suzaku's X-ray telescopes and data-processing software, and it continues to operate a facility that supports U.S. astronomers who use the spacecraft.

Suzaku is the fifth Japanese X-ray astronomy satellite. It was launched as Astro-E2 on July 10, 2005, and renamed in orbit. The observatory was developed at JAXA's Institute of Space and Astronautical Science in collaboration with NASA and other Japanese and U.S. institutions.

Space Shuttle Commander Mark Kelly will not be available for media interviews that had been scheduled from 3 p.m.-5 p.m. CDT Thursday, March 24, at the agency's Johnson Space Center in Houston. Kelly will participate in a previously scheduled news conference with his crew at 2 p.m. CDT Thursday to discuss their upcoming STS-134 shuttle mission to the International Space Station.

The news conference will air live on NASA Television and the agency's website.

The other STS-134 crew members, pilot Greg H. Johnson and Mission Specialists Michael
Fincke, Greg Chamitoff, Andrew Feustel and European Space Agency astronaut Roberto Vittori, will be available for previously scheduled interviews from 3 p.m.-6 p.m. CDT Thursday.

All other Thursday briefings related to the STS-134 mission remain as planned.

NASA's Stennis Space Center is moving ahead in supporting Orbital Sciences Corporation testing of Aerojet's AJ26 engines for commercial cargo flights to the International Space Station.

Orbital plans to launch the first of eight scheduled unmanned cargo missions to the ISS in early 2012. Key steps already have been taken toward that goal as Orbital has successfully tested the Aerojet AJ26 engines that will power the first stage of their Taurus II rocket. Tests on each of the engines were performed by a team of Orbital, Aerojet and John C. Stennis Space Center engineers at NASA’s south Mississippi test facility. The latest test was conducted on March 19 on the E-1 Test Stand.

The initial two engines, tested earlier this year, will be delivered to Orbital at the Wallops Flight Facility launch site in Virginia for integration with the Taurus II’s first stage core.Orbital is developing its Taurus II's cargo logistics system under the joint Commercial Orbital Transportation Services demonstration project with NASA, and is scheduled to carry out its ISS cargo resupply missions under the Commercial Resupply Services contract.

Hopes for reviving NASA Spirit Mars rover dimmed further with passage last week of the point at which the rover's locale received its maximum sunshine for the Martian year.

The rover team has tried to contact Spirit for months with strategies based on the possibility that increasing energy availability might wake the rover from hibernation. The team has now switched to communication strategies designed to address more than one problem on the rover. If no signal is heard from Spirit in the next month or two, the team at NASA's Jet Propulsion Laboratory, Pasadena, Calif., will shift to single-rover operations, continuing to operate Spirit's active twin, Opportunity.

"The commands we are sending starting this week should work in a multiple-fault scenario where Spirit's main transmitter is no longer working and the mission clock has lost track of time or drifted significantly," said JPL's John Callas, project manager for Spirit and Opportunity.

Spirit landed on Mars Jan. 4, 2004 Universal Time for a mission designed to last for three months. After accomplishing its prime-mission goals, Spirit worked for more than five years in bonus-time extended missions.

Spirit has not communicated since March 22, 2010. Power output from its solar array had been waning prior to that, and the rover had been expected to go into a low-power hibernation mode. With drive motors on two of its six wheels no longer working, Spirit had been unable in preceding months to maneuver much in its sand-trap location. The rover could not get to a favorable tilt for its solar panels as Martian winter approached.

During the Martian winter with most heaters turned off, Spirit experienced colder internal temperatures than in any of its three previous winters on Mars. The cold could have damaged any of several electronic components that, if damaged, would prevent reestablishing communication with Spirit.

However, attempts to regain contact have continued for more than eight months in the possibility that the seasonal increase in solar energy available at Spirit's location would revive the rover. NASA's Deep Space Network of antennas in California, Spain and Australia has been listening for Spirit daily. The rover team has also sent commands to elicit a response from the rover even if the rover has lost track of time, or if its receiver has degraded in frequency response.

The available solar energy at Spirit's site was estimated to peak on March 10. Revised commanding began March 15, including instructions for the rover to be receptive over UHF relay to hailing from the Mars orbiters for extended periods of time and to use a backup transmitter on the rover.

Spirit and Opportunity both have made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life. Opportunity landed three weeks after Spirit.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Science Mission Directorate, Washington.

NASA's MESSENGER spacecraft successfully achieved orbit around Mercury at approximately 9 p.m. EDT Thursday. This marks the first time a spacecraft has accomplished this engineering and scientific milestone at our solar system's innermost planet.

"This mission will continue to revolutionize our understanding of Mercury during the coming year," said NASA Administrator Charles Bolden, who was at MESSENGER mission control at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., as engineers received telemetry data confirming orbit insertion. "NASA science is rewriting text books. MESSENGER is a great example of how our scientists are innovating to push the envelope of human knowledge."

At 9:10 p.m. EDT, engineers Operations Center, received the anticipated radiometric signals confirming nominal burn shutdown and successful insertion of the MESSENGER probe into orbit around the planet Mercury. NASA's MErcury Surface, Space ENvironment, Geochemistry, and Ranging, or MESSENGER, rotated back to the Earth by 9:45 p.m. EDT, and started transmitting data. Upon review of the data, the engineering and operations teams confirmed the burn executed nominally with all subsystems reporting a clean burn and no logged errors.

MESSENGER's main thruster fired for approximately 15 minutes at 8:45 p.m., slowing the spacecraft by 1,929 miles per hour and easing it into the planned orbit about Mercury. The rendezvous took place about 96 million miles from Earth.

"Achieving Mercury orbit was by far the biggest milestone since MESSENGER was launched more than six and a half years ago," said Peter Bedini, MESSENGER project manager of the Applied Physics Laboratory (APL). "This accomplishment is the fruit of a tremendous amount of labor on the part of the navigation, guidance-and-control, and mission operations teams, who shepherded the spacecraft through its 4.9-billion-mile journey."

For the next several weeks, APL engineers will be focused on ensuring the spacecraft's systems are all working well in Mercury's harsh thermal environment. Starting on March 23, the instruments will be turned on and checked out, and on April 4 the mission's primary science phase will begin.

"Despite its proximity to Earth, the planet Mercury has for decades been comparatively unexplored," said Sean Solomon, MESSENGER principal investigator of the Carnegie Institution of Washington. "For the first time in history, a scientific observatory is in orbit about our solar system's innermost planet. Mercury's secrets, and the implications they hold for the formation and evolution of Earth-like planets, are about to be revealed."

APL designed and built the spacecraft. The lab manages and operates the mission for NASA's Science Mission Directorate in Washington.

The crew of STS-133 closed out space shuttle Discovery's roster of accomplishments with a virtually flawless 13-day flight to attach a new module to the International Space Station and help the residents there outfit the orbiting laboratory for continued research.

Commander Steve Lindsey, Pilot Eric Boe and Mission Specialists Alvin Drew, Michael Barratt, Nicole Stott and Steve Bowen lifted off aboard Discovery on Feb. 24, 2011, from NASA's Kennedy Space Center in Florida to begin the spacecraft's pursuit of the station.

With Lindsey at the controls, Discovery rendezvoused with the station two days later and then backed the shuttle to its berthing port. Discovery's docking completed the rare occasion of having vehicles from the United States, Russia, Europe and Japan connected to the International Space Station at the same time. Along with the shuttle and the Russian Soyuz capsules, the European Space Agency's uncrewed Automated Transferred Vehicle-2 and the Japan Aerospace Exploration Agency's H-II Transfer Vehicle, or HTV, were attached to the station.

Discovery's six astronauts joined the six residents on the station for a quick welcome before they teamed up to move an equipment platform out of the shuttle's cargo bay and onto the station's truss.

The Express Logistics Carrier had been loaded on Earth with spare parts for the station, including a radiator to cool the station's systems. The parts will not be installed until they are needed as replacements.

Barratt and Stott operated the space station's robotic arm to lift the platform out of Discovery's cargo bay. They handed it off to the shuttle's own robotic arm, worked by Boe and Drew. After the station arm was maneuvered to a new location, the shuttle arm was used to hand it back to the station arm, which maneuvered the platform to its final location on the station's backbone.

Drew and Bowen left the station's Quest airlock Feb. 28 on the first of two spacewalks planned for the mission. Working inside Discovery's cargo bay and on the station, the duo put the finishing touches on the outside of the Permanent Multipurpose Module, or PMM, so it could be installed on the station and they moved a failed pump module to a stowage platform where it will stay until it can be brought back to Earth for evaluation.

Station Commander Scott Kelly worked with Barratt to drive the station's robotic arm during the spacewalk to assist Bowen and Drew. Although a glitch in the arm's control system prompted them to move to a backup location, the spacewalk's objectives were completed.

Barratt and Stott took the controls of the station's robotic arm again the next day to attach the new module to the underside of the station, connecting it to the Earth-facing side of the Unity node. The PMM is a closet for the space station, giving the crew more room to store equipment and supplies. Technicians retrofitted the Italian-built Leonardo resupply module with meteorite shielding and other gear so it could be permanently attached to the station.

The module went into space loaded with equipment, experiments and supplies for the station, so the shuttle and station crews worked throughout the mission to unpack some of the material in the PMM as well as the supplies inside the European and Japanese cargo ships.

Bowen and Drew ventured outside the station again on the mission's seventh day in space. Bowen, riding the station's robotic arm, disconnected an experiment rack from the outside of the Columbus laboratory module and Drew removed covers from the logistics carrier Discovery brought up.

The crews of both spacecraft spent the next week working inside the space station to prepare it for continuing research operations. Outfitting work inside the PMM included removing launch supports and putting unneeded materials into the HTV, which will be jettisoned later to burn up in the atmosphere.

Discovery left the space station Monday, March 7 and its crew began prepping the shuttle for its final glide back to Earth.

The shuttle soared through mostly clear skies over Florida on Wednesday, March 9. Lindsey guided Discovery onto Kennedy's runway at 11:57 a.m. EST.

After the landing, reflection mixed with celebration after Discovery completed the last of its 39 missions into orbit. Lindsey and his crew walked beneath the shuttle with NASA officials including Administrator Charles Bolden.

"I am so glad we got to land here at Kennedy, the home of Discovery," STS-133 Commander Steve Lindsey said. "As the minutes pass, I'm actually getting sadder and sadder about this being the last flight and I know all the folks involved with the shuttle program feel the same way."

After more than a dozen laps through the inner solar system, NASA's MESSENGER spacecraft will move into orbit around Mercury on March 17, 2011. The durable spacecraft--carrying seven science instruments and fortified against the blistering environs near the sun--will be the first to orbit the innermost planet.

At 8:45 p.m. EDT, MESSENGER--having pointed its largest thruster very close to the direction of travel--will fire that thruster for nearly 14 minutes, with other thrusters firing for an additional minute, slowing the spacecraft by 862 meters per second (1,929 mph) and consuming 31 percent of the propellant that the spacecraft carried at launch. Less than 9.5 percent of the usable propellant at the start of the mission will remain after completing the orbit insertion maneuver, but the spacecraft will still have plenty of propellant for future orbit correction maneuvers.

The orbit insertion will place the spacecraft into a 12-hour orbit about Mercury with a 200 kilometer (124 mile) minimum altitude. At the time of orbit insertion, MESSENGER will be 46.14 million kilometers (28.67 million miles) from the sun and 155.06 million kilometers (96.35 million miles) from Earth.
MESSENGER has been on a six-year mission to become the first spacecraft to orbit Mercury. The spacecraft followed a path through the inner solar system, including one flyby of Earth, two flybys of Venus, and three flybys of Mercury. This impressive journey is returning the first new spacecraft data from Mercury since the Mariner 10 mission over 30 years ago.

On March 7, antennas from each of the three Deep Space Network (DSN) ground stations began continuous monitoring, allowing flight control engineers at the Johns Hopkins University Applied Physics Laboratory to observe MESSENGER on its final approach to Mercury. The spacecraft also began executing the last cruise command sequence of the mission, when the command sequence containing the orbit-insertion burn will start.

"This is a milestone event for our small, but highly experienced, operations team, marking the end of six and one half years of successfully shepherding the spacecraft through six planetary flybys, five major propulsive maneuvers, and sixteen trajectory-correction maneuvers, all while simultaneously preparing for orbit injection and primary mission operations," said MESSENGER Systems Engineer Eric Finnegan. "Whatever the future holds, this team of highly dedicated engineers has done a phenomenal job methodically generating, testing, and verifying commands to the spacecraft, getting MESSENGER where it is today."

"The cruise phase of the MESSENGER mission has reached the end game," adds MESSENGER Principal investigator Sean Solomon, of the Carnegie Institution of Washington. "Orbit insertion is the last hurdle to a new game level, operation of the first spacecraft in orbit about the solar system's innermost planet. The MESSENGER team is ready and eager for orbital operations to begin."

The March 11, magnitude 9.0 earthquake in Japan may have shortened the length of each Earth day and shifted its axis. But don't worry—you won't notice the difference. 

Using a United States Geological Survey estimate for how the fault responsible for the earthquake slipped, research scientist Richard Gross of NASA's Jet Propulsion Laboratory, Pasadena, Calif., applied a complex model to perform a preliminary theoretical calculation of how the Japan earthquake—the fifth largest since 1900—affected Earth's rotation. His calculations indicate that by changing the distribution of Earth's mass, the Japanese earthquake should have caused Earth to rotate a bit faster, shortening the length of the day by about 1.8 microseconds (a microsecond is one millionth of a second). 

The calculations also show the Japan quake should have shifted the position of Earth's figure axis (the axis about which Earth's mass is balanced) by about 17 centimeters (6.5 inches), towards 133 degrees east longitude. Earth's figure axis should not be confused with its north-south axis; they are offset by about 10 meters (about 33 feet). This shift in Earth's figure axis will cause Earth to wobble a bit differently as it rotates, but it will not cause a shift of Earth's axis in space—only external forces such as the gravitational attraction of the sun, moon and planets can do that. 

Both calculations will likely change as data on the quake are further refined. 

In comparison, following last year's magnitude 8.8 earthquake in Chile, Gross estimated the Chile quake should have shortened the length of day by about 1.26 microseconds and shifted Earth's figure axis by about 8 centimeters (3 inches). A similar calculation performed after the 2004 magnitude 9.1 Sumatran earthquake revealed it should have shortened the length of day by 6.8 microseconds and shifted Earth's figure axis by about 7 centimeters, or 2.76 inches. How an individual earthquake affects Earth's rotation depends on its size (magnitude), location and the details of how the fault slipped. 

Gross said that, in theory, anything that redistributes Earth's mass will change Earth's rotation.
"Earth's rotation changes all the time as a result of not only earthquakes, but also the much larger effects of changes in atmospheric winds and oceanic currents," he said. "Over the course of a year, the length of the day increases and decreases by about a millisecond, or about 550 times larger than the change caused by the Japanese earthquake. The position of Earth's figure axis also changes all the time, by about 1 meter (3.3 feet) over the course of a year, or about six times more than the change that should have been caused by the Japan quake." 

Gross said that while we can measure the effects of the atmosphere and ocean on Earth's rotation, the effects of earthquakes, at least up until now, have been too small to measure. The computed change in the length of day caused by earthquakes is much smaller than the accuracy with which scientists can currently measure changes in the length of the day. However, since the position of the figure axis can be measured to an accuracy of about 5 centimeters (2 inches), the estimated 17-centimeter shift in the figure axis from the Japan quake may actually be large enough to observe if scientists can adequately remove the larger effects of the atmosphere and ocean from the Earth rotation measurements. He and other scientists will be investigating this as more data become available. 

Gross said the changes in Earth's rotation and figure axis caused by earthquakes should not have any impacts on our daily lives. "These changes in Earth's rotation are perfectly natural and happen all the time," he said. "People shouldn't worry about them."

Dr. James Garvin, chief scientist at NASA's Goddard Space Flight Center, answers your questions about the 'supermoon' phenomenon.

Question: What is the definition of a supermoon and why is it called that?
'Supermoon' is a situation when the moon is slightly closer to Earth in its orbit than on average, and this effect is most noticeable when it occurs at the same time as a full moon. So, the moon may seem bigger although the difference in its distance from Earth is only a few percent at such times.
It is called a supermoon because this is a very noticeable alignment that at first glance would seem to have an effect. The 'super' in supermoon is really just the appearance of being closer, but unless we were measuring the Earth-Moon distance by laser rangefinders (as we do to track the LRO [Lunar Reconnaissance Orbiter] spacecraft in low lunar orbit and to watch the Earth-Moon distance over years), there is really no difference. The supermoon really attests to the wonderful new wealth of data NASA's LRO mission has returned for the Moon, making several key science questions about our nearest neighbor all the more important.

Are there any adverse effects on Earth because of the close proximity of the moon?

The effects on Earth from a supermoon are minor, and according to the most detailed studies by terrestrial seismologists and volcanologists, the combination of the moon being at its closest to Earth in its orbit, and being in its 'full moon' configuration (relative to the Earth and sun), should not affect the internal energy balance of the Earth since there are lunar tides every day. The Earth has stored a tremendous amount of internal energy within its thin outer shell or crust, and the small differences in the tidal forces exerted by the moon (and sun) are not enough to fundamentally overcome the much larger forces within the planet due to convection (and other aspects of the internal energy balance that drives plate tectonics). Nonetheless, these supermoon times remind us of the effect of our 'Africa-sized' nearest neighbor on our lives, affecting ocean tides and contributing to many cultural aspects of our lives (as a visible aspect of how our planet is part of the solar system and space).


NASA will unveil its new rocket integration facility at the Wallops Flight Facility in Virginia during a ribbon-cutting ceremony at 10 a.m. EDT on March 22.

The Horizontal Integration Facility will support medium-class mission capabilities. The first customer to use the facility will be Orbital Sciences Corp. of Dulles, Va., with its Taurus II launch vehicle.

Orbital will conduct missions for NASA under the agency's Commercial Orbital Transportation Services project and Commercial Resupply Services program. Integration of the Taurus II in the facility will begin this month, with the first launch expected later this year.

Before space shuttle Discovery's STS-133 crew members departed NASA's Kennedy Space Center in Florida for their home base at NASA's Johnson Space Center in Houston, they gathered in Kennedy's TV Auditorium to briefly answer questions from the media.

STS-133 Commander Steve Lindsey was first to say, "It was a great day to come back and land in Florida, we're happy to bring Discovery home."

When asked how emotional the landing was, Lindsey said, "As hard as it was to leave the flight deck when we were all done - at least for me it was - we were really focused today on bringing it home safe. We were really working hard the whole mission and didn't have a whole lot of time to reflect about that."

"I did notice when I was on the ramp and walking around afterward as the minutes passed I kind of got more and more sad looking at the vehicle and how healthy it is and wonderful it performed, not just on this flight but the other two flights that I flew on, as well as every other flight," Lindsey continued. "It kind of got sadder for me as the minutes rolled past."

Mission Specialist Steve Bowen, who replaced Tim Kopra on the mission after a bicycle accident kept him earthbound, said Kopra was with them not only in spirit but in constant contact via the Mission Control Center in Houston.

"He actually helped us through the EVA's from the ground, which I greatly appreciated," said Bowen. "Just having him in mission control to be able to question things and know that if I wasn't doing something quite right, he was going to step in and help me out."

The crew of Discovery's STS-133 mission, the final flight for NASA's oldest active shuttle, will be honored at a welcome ceremony tomorrow at Ellington Field near Houston. Meanwhile, space shuttle Endeavour's move, or "rollout" to Launch Pad 39A has been delayed for at least 24 hours, due to predictions of unfavorable weather. Managers will meet Thursday morning to reassess weather conditions for the next rollout attempt.

NASA will preview the final space shuttle missions during media events on Wednesday, March 23, and Thursday, March 24, at the agency's Johnson Space Center in Houston.

On March 23, reporters are invited to a media availability with three of the four STS-135 crew members who will fly aboard Atlantis on the final shuttle flight in June. STS-135 Commander Chris Ferguson, Pilot Doug Hurley and Mission Specialist Sandra Magnus will demonstrate a shuttle rendezvous and docking to the International Space Station in Johnson's domed simulation facility. Reporters can film and photograph the crew, instructors and engineering support teams, as well as try the task first-hand.

On March 24, there will be a series of news briefings about shuttle Endeavour's STS-134 mission targeted to launch on April 19. NASA Television and the agency's website will broadcast the briefings live. Reporters will be able to ask questions from participating NASA locations.

8 a.m. -- Program Overview
9:30 a.m. -- STS-134 Mission Overview
11:30 a.m. -- STS-134 Spacewalk Overview
12:30 p.m. -- Alpha Magnetic Spectrometer Briefing
2 p.m. -- STS-134 Crew News Conference

The STS-134 crew will be available for interviews at Johnson by phone or in person after the briefings. To reserve an interview opportunity, reporters must contact Gayle Frere at 281-483-8645 by 5 p.m. on March 18.

To attend the STS-134 events and the STS-135 availability at Johnson, reporters must contact the Johnson newsroom at 281-483-5111 by 5 p.m. on March 14 for credentials. All required paperwork for international journalists must be submitted to the newsroom by March 14.

STS-134's 14-day mission to the International Space Station will deliver the Alpha Magnetic Spectrometer, a particle physics detector designed to operate from the station and search for various types of unusual matter. The shuttle crew also will deliver spare parts, including two S-band communications antennas, a high-pressure gas tank and additional parts for the Dextre robot. The crew also will transfer Endeavour's orbiter boom sensor system to the station truss as a permanent fixture to assist spacewalkers, if required.

STS-134 will include four spacewalks. As Endeavour undocks from the station to return to Earth, Commander Mark Kelly and Pilot Greg H. Johnson will ease the shuttle back toward the station to test new sensor technologies that could make it easier for future space vehicles to dock to the International Space Station.

Kelly and Johnson will be joined by Mission Specialists Michael Fincke, Greg Chamitoff, Andrew Feustel and European Space Agency astronaut Roberto Vittori.

The NASA Authorization Act of 2010 directs NASA to conduct the STS-135 mission, and the teams are preparing for the target launch date of June 28. More information on mission preview briefings, which are targeted for mid-June, will be forthcoming. Atlantis will carry the Raffaello multipurpose logistics module to deliver supplies, logistics and spare parts to the station. The mission also will fly a system to investigate the potential for remote-controlled robot refueling of satellites and spacecraft in orbit.

NASA's space shuttle fleet began setting records with its first launch on April 12, 1981 and continues to set high marks of achievement and endurance. Starting with Columbia and continuing with Challenger, Discovery, Atlantis and Endeavour, the spacecraft has carried people into orbit repeatedly, launched, recovered and repaired satellites, conducted cutting-edge research and built the largest structure in space, the International Space Station.

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

On this page, you'll find a collection of feature stories and videos documenting space shuttle operations. You'll also receive an insider's perspective of what it takes to maintain and fly this technological marvel.

At 4:11 p.m. EST, hatches were closed between space shuttle Discovery and the International Space Station. The hatches between the two spacecraft were opened at 4:16 p.m. on February 26 and remained open for joint crew operations for a total of 7 days, 23 hours, and 55 minutes.

Prior to hatch closure, the shuttle and station crews exchanged farewells. Discovery Commander Steve Lindsey thanked station Commander Scott Kelly for the hospitality. Kelly responded, “It was a very successful time onboard. We enjoyed having you as guests, we’re going to miss you, and we’re going to miss space shuttle Discovery. Discovery been a great ship and has really supported ISS more than any other shuttle and we wish her fair winds and following seas. Thank you.”

Discovery’s six crew members will awaken to a special song with a surprise twist at 3:23 a.m. Monday, “Theme from Star Trek” by Alexander Courage.

The Discovery crew’s sleep period begins at 7:23 p.m. EST, with a wakeup call scheduled for 3:23 a.m. Saturday. Highlights of Flight Day 9 will be replayed hourly on NASA Television during crew sleep beginning at 8 p.m.

During the afternoon Friday, Mission Specialists Steve Bowen and Alvin Drew stowed tools they used outside on the spacewalks earlier this week. Meanwhile their colleagues continued with Leonardo Permanent Multipurpose Module activities, moving supplies and equipment from the new module into the station and outfitting the interior of the module.

Earlier in the day, all 12 shuttle and station crew members gathered for the joint news conference. They took questions from reporters at Johnson Space Center, Kennedy Space Center and in Italy.

Both the Glory spacecraft and Taurus XL rocket are ready for launch tomorrow morning at 2:09:43 a.m. PST/5:09:43 a.m. EST. The weather forecast is 100 percent "go" with the possibility of some fog and a low ceiling not expected to be an issue. The call to stations for the launch team is 10:20 p.m. PST/1:20 a.m. EST.

The liftoff from Vandenberg Air Force Base in California is targeted for the middle of a 48-second launch window. Spacecraft separation will occur 13 minutes after launch. Coverage of the countdown on the Glory launch blog and on NASA TV will begin on launch day at 3:30 a.m. EST. Technical issues with ground support equipment for the Taurus XL launch vehicle led to the scrub of the first launch attempt on Feb. 23.

Data from the Glory mission will allow scientists to better understand how the sun and tiny atmospheric particles called aerosols affect Earth's climate. Both aerosols and solar energy influence the planet's energy budget -- the amount of energy entering and exiting Earth's atmosphere. An accurate measurement of these impacts is important in order to anticipate future changes to our climate and how they may affect human life.

Project management for Glory is the responsibility of NASA's Goddard Space Flight Center in Greenbelt, Md. The launch management for the mission is the responsibility of NASA's Launch Services Program at the Kennedy Space Center in Florida. Orbital Sciences Corp. of Dulles, Va., is the launch service provider to Kennedy of the four-stage Taurus XL rocket and is also builder of the Glory satellite for Goddard.

Spacewalkers Steve Bowen and Alvin Drew completed a six-hour, 14-minute spacewalk at 4:56 p.m. EST.

This was the final STS-133 spacewalk, the 244th by U.S. astronauts. It was the seventh for Bowen totaling 47 hours, 18 minutes and places him sixth on the all-time list. It was the second spacewalk for Drew, totaling 12 hours, 48 minutes. It was the 155th spacewalk in support of International Space Station assembly and maintenance, totaling 973 hours, 53 minutes, equal to 40 full days of spacewalks.

NASA's Glory spacecraft is scheduled for launch on Friday, March 4. Technical issues with ground support equipment for the Taurus XL launch vehicle led to the scrub of the original Feb. 23 launch attempt. Those issues have been resolved.

The liftoff from Vandenberg Air Force Base in California is targeted for 5:09:43 a.m. EST, in the middle of a 48-second launch window. Spacecraft separation occurs 13 minutes after launch.

Coverage of the countdown on the Glory launch blog and on NASA TV will begin on launch day at 3:30 a.m. EST.

Data from the Glory mission will allow scientists to better understand how the sun and tiny atmospheric particles called aerosols affect Earth's climate. Both aerosols and solar energy influence the planet's energy budget -- the amount of energy entering and exiting Earth's atmosphere. An accurate measurement of these impacts is important in order to anticipate future changes to our climate and how they may affect human life.

Project management for Glory is the responsibility of NASA's Goddard Space Flight Center in Greenbelt, Md. The launch management for the mission is the responsibility of NASA's Launch Services Program at the Kennedy Space Center in Florida. Orbital Sciences Corp. of Dulles, Va., is the launch service provider to Kennedy of the four-stage Taurus XL rocket and is also builder of the Glory satellite for Goddard.