Cassini Spacecraft Captures Images and Sounds of Big Saturn Storm

PASADENA, Calif. – Scientists analyzing data from NASA's Cassini spacecraft now have the first-ever, up-close details of a Saturn storm that is eight times the surface area of Earth.

On Dec. 5, 2010, Cassini first detected the storm that has been raging ever since. It appears at approximately 35 degrees north latitude on Saturn. Pictures from Cassini's imaging cameras show the storm wrapping around the entire planet covering approximately 1.5 billion square miles (4 billion square kilometers).

The storm is about 500 times larger than the biggest storm previously seen by Cassini during several months from 2009 to 2010. Scientists studied the sounds of the new storm's lightning strikes and analyzed images taken between December 2010 and February 2011. Data from Cassini's radio and plasma wave science instrument showed the lightning flash rate as much as 10 times more frequent than during other storms monitored since Cassini's arrival to Saturn in 2004. The data appear in a paper published this week in the journal Nature.

"Cassini shows us that Saturn is bipolar," said Andrew Ingersoll, an author of the study and a Cassini imaging team member at the California Institute of Technology in Pasadena, Calif. "Saturn is not like Earth and Jupiter, where storms are fairly frequent. Weather on Saturn appears to hum along placidly for years and then erupt violently. I'm excited we saw weather so spectacular on our watch."

At its most intense, the storm generated more than 10 lightning flashes per second. Even with millisecond resolution, the spacecraft's radio and plasma wave instrument had difficulty separating individual signals during the most intense period. Scientists created a sound file from data obtained on March 15 at a slightly lower intensity period.

Cassini has detected 10 lightning storms on Saturn since the spacecraft entered the planet's orbit and its southern hemisphere was experiencing summer, with full solar illumination not shadowed by the rings. Those storms rolled through an area in the southern hemisphere dubbed "Storm Alley." But the sun's illumination on the hemispheres flipped around August 2009, when the northern hemisphere began experiencing spring.

"This storm is thrilling because it shows how shifting seasons and solar illumination can dramatically stir up the weather on Saturn," said Georg Fischer, the paper's lead author and a radio and plasma wave science team member at the Austrian Academy of Sciences in Graz. "We have been observing storms on Saturn for almost seven years, so tracking a storm so different from the others has put us at the edge of our seats."

The storm's results are the first activities of a new "Saturn Storm Watch" campaign. During this effort, Cassini looks at likely storm locations on Saturn in between its scheduled observations. On the same day that the radio and plasma wave instrument detected the first lightning, Cassini's cameras happened to be pointed at the right location as part of the campaign and captured an image of a small, bright cloud. Because analysis on that image was not completed immediately, Fischer sent out a notice to the worldwide amateur astronomy community to collect more images. A flood of amateur images helped scientists track the storm as it grew rapidly, wrapping around the planet by late January 2011.

The new details about this storm complement atmospheric disturbances described recently by scientists using Cassini's composite infrared spectrometer and the European Southern Observatory's Very Large Telescope. The storm is the biggest observed by spacecraft orbiting or flying by Saturn. NASA's Hubble Space Telescope captured images in 1990 of an equally large storm.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena manages the mission for the agency's Science Mission Directorate in Washington. The radio and plasma wave science team is based at the University of Iowa, Iowa City, where the instrument was built. The imaging team is based at the Space Science Institute in Boulder, Colo. JPL is a division of the California Institute of Technology, Pasadena.

See Beautiful Ontario Lacus: Cassini's Guided Tour

Ontario Lacus, the largest lake in the southern hemisphere of Saturn's moon Titan, turns out to be a perfect exotic vacation spot, provided you can handle the frosty, subzero temperatures and enjoy soaking in liquid hydrocarbon.

Several recent papers by scientists working with NASA's Cassini spacecraft describe evidence of beaches for sunbathing in Titan's low light, sheltered bays for mooring boats, and pretty deltas for wading out in the shallows. They also describe seasonal changes in the lake's size and depth, giving vacationers an opportunity to visit over and over without seeing the same lake twice. (Travel agents, of course, will have to help you figure out how to breathe in an atmosphere devoid of oxygen.)

Using data that give us the most detailed picture yet of a lake on another world, scientists and animators have collaborated on a new video tour of Ontario Lacus based on radar data from Cassini's Titan flybys on June 22, 2009, July 8, 2009, and Jan. 12, 2010. A Web video explaining how scientists look to Earth's Death Valley to understand places like Titan's Ontario Lacus is available at: http://www.nasa.gov/multimedia/videogallery/index.html?collection_id=14658&media_id=16290407

"With such frigid temperatures and meager sunlight, you wouldn't think Titan has a lot in common with our own Earth," said Steve Wall, deputy team lead for the Cassini radar team, based at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "But Titan continues to surprise us with activity and seasonal processes that look marvelously, eerily familiar."

Cassini arrived at Saturn in 2004 when the southern hemisphere of the planet and its moons were experiencing summer. The seasons have started to change toward autumn, with winter solstice darkening the southern hemisphere of Titan in 2017. A year on Titan is the equivalent of about 29 Earth years.

This image of Ontario Lacus, the largest lake on the southern hemisphere of Saturn's moon Titan, was obtained by NASA's Cassini spacecraft on Jan. 12, 2010. Image Credit: NASA/JPL-Caltech

Titan is the only other world in our solar system known to have standing bodies of liquid on its surface. Because surface temperatures at the poles average a chilly 90 Kelvin (about minus 300 degrees Fahrenheit), the liquid is a combination of methane, ethane and propane, rather than water. Ontario Lacus has a surface area of about 15,000 square kilometers (6,000 square miles), slightly smaller than its terrestrial namesake Lake Ontario.

Cassini first obtained an image of Ontario Lacus with its imaging camera in 2004. A paper submitted to the journal Icarus by Alex Hayes, a Cassini radar team associate at the California Institute of Technology in Pasadena, and colleagues finds that the lake's shoreline has receded by about 10 kilometers (6 miles). This has resulted in a liquid level reduction of about 1 meter (3 feet) per year over a four–year period.

The shoreline appears to be receding because of liquid methane evaporating from the lake, with a total amount of evaporation that would significantly exceed the yearly methane gas output of all the cows on Earth, Hayes said. Some of the liquid could also seep into porous ground material. Hayes said the changes in the lake are likely occurring as part of Titan's seasonal methane cycle, and would be expected to reverse during southern winter.

This seasonal filling and receding is similar to what occurs at the shallow lakebed known as Racetrack Playa in Death Valley National Park, Hayes said. In fact, from the air, the topography and shape of Racetrack Playa and Ontario Lacus are quite similar, although Ontario Lacus is about 60 times larger.

"We are very excited about these results, because we did not expect Cassini to be able to detect changes of this magnitude in Titan's lakes," Hayes said. "It is only through the continued monitoring of seasonal variation during Cassini's extended mission that these discoveries have been made possible."

Other parts of the Ontario Lacus' shoreline, as described in the paper published in Geophysical Research Letters in March 2010 by Wall, Hayes and other colleagues, show flooded valleys and coasts, further proof that the lake level has changed.

The delta revealed by Cassini radar data on the western shore of Ontario Lacus is also the first well-developed delta observed on Titan, Wall said. He explained that the shape of the land there shows liquid flowing down from a higher plain switching channels on its way into the lake, forming at least two lobes.

Examples of this kind of channel switching and wave-modified deltas can be found on Earth at the southern end of Lake Albert between Uganda and the Democratic Republic of Congo in Africa, and the remains of an ancient lake known as Megachad in the African country Chad, Wall said.

The radar data also show a smooth beach on the northwestern shore of Ontario Lacus. Smooth lines parallel to the current shoreline could be formed by low waves over time, which were likely driven by winds sweeping in from the west or southwest. The pattern at Ontario Lacus resembles what might be seen on the southeastern side of Lake Michigan, where waves sculpt the shoreline in a similar fashion.

"Cassini continues to take our breath away as it fills in the details on the surfaces of these far-off moons," said Linda Spilker, Cassini project scientist based at JPL. "It's exhilarating to ride along as it takes us on the ultimate cold-weather adventure."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the Cassini-Huygens mission for NASA's Science Mission Directorate. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

More Cassini information is available, at http://www.nasa.gov/cassini, http://saturn.jpl.nasa.gov.

For more information visit http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20100715.html

NASA Finds Super-Hot Planet with Unique Comet-Like Tail

Astronomers using NASA's Hubble Space Telescope have confirmed the existence of a baked object that could be called a "cometary planet." The gas giant planet, named HD 209458b, is orbiting so close to its star that its heated atmosphere is escaping into space.

Observations taken with Hubble's Cosmic Origins Spectrograph (COS) suggest powerful stellar winds are sweeping the cast-off atmospheric material behind the scorched planet and shaping it into a comet-like tail.

"Since 2003 scientists have theorized the lost mass is being pushed back into a tail, and they have even calculated what it looks like," said astronomer Jeffrey Linsky of the University of Colorado in Boulder, leader of the COS study. "We think we have the best observational evidence to support that theory. We have measured gas coming off the planet at specific speeds, some coming toward Earth. The most likely interpretation is that we have measured the velocity of material in a tail."

The planet, located 153 light-years from Earth, weighs slightly less than Jupiter but orbits 100 times closer to its star than the Jovian giant. The roasted planet zips around its star in a short 3.5 days. In contrast, our solar system's fastest planet, Mercury, orbits the Sun in 88 days. The extrasolar planet is one of the most intensely scrutinized, because it is the first of the few known alien worlds that can be seen passing in front of, or transiting, its star. Linsky and his team used COS to analyze the planet's atmosphere during transiting events. During a transit, astronomers study the structure and chemical makeup of a planet's atmosphere by sampling the starlight that passes through it. The dip in starlight because of the planet's passage, excluding the atmosphere, is very small, only about 1.5 percent. When the atmosphere is added, the dip jumps to 8 percent, indicating a bloated atmosphere.

Illustration Credit: NASA, ESA, and G. Bacon (STScI)

COS detected the heavy elements carbon and silicon in the planet's super-hot, 2,000-degree-Fahrenheit atmosphere. This detection revealed the parent star is heating the entire atmosphere, dredging up the heavier elements and allowing them to escape the planet.

The COS data also showed the material leaving the planet was not all traveling at the same speed. "We found gas escaping at high velocities, with a large amount of this gas flowing toward us at 22,000 miles per hour," Linsky said. "This large gas flow is likely gas swept up by the stellar wind to form the comet-like tail trailing the planet."

Hubble's newest spectrograph has the ability to probe a planet's chemistry at ultraviolet wavelengths not accessible to ground-based telescopes. COS is proving to be an important instrument for probing the atmospheres of "hot Jupiters" like HD 209458b.

Another Hubble instrument, the Space Telescope Imaging Spectrograph (STIS), observed the planet in 2003. The STIS data showed an active, evaporating atmosphere, and a comet-tail-like structure was suggested as a possibility. But STIS wasn't able to obtain the spectroscopic detail necessary to show a tail, or an Earthward-moving component of the gas, during transits. The tail was detected for the first time because of the unique combination of very high ultraviolet sensitivity and good spectral resolution provided by COS.

Although this extreme planet is being roasted by its star, it won't be destroyed anytime soon. "It will take about a trillion years for the planet to evaporate," Linsky said.

The results appeared in the July 10 issue of The Astrophysical Journal.

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

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

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

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

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

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

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

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

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

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

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

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

The Coolest Stars Come Out of the Dark

Astronomers have uncovered what appear to be 14 of the coldest stars known in our universe. These failed stars, called brown dwarfs, are so cold and faint that they'd be impossible to see with current visible-light telescopes. Spitzer's infrared vision was able to pick out their feeble glow, much as a firefighter uses infrared goggles to find hot spots buried underneath a dark forest floor.

The brown dwarfs join only a handful of similar objects previously discovered. The new objects are between the temperatures of about 450 Kelvin to 600 Kelvin (350 to 620 degrees Fahrenheit). As far as stars go, this is bitter cold -- as cold, in some cases, as planets around other stars.

These cool orbs have remained elusive for years, but will soon start coming out of the dark in droves. NASA's Wide-field Infrared Survey Explorer (WISE) mission, which is up scanning the entire sky now in infrared wavelengths, is expected to find hundreds of objects of a similarly chilly disposition, if not even colder. WISE is searching a volume of space 40 times larger than that sampled in the recent Spitzer study, which concentrated on a region in the constellation Boötes. The Spitzer mission is designed to look at targeted patches of sky in detail, while WISE is combing the whole sky.

"WISE is looking everywhere, so the coolest brown dwarfs are going to pop up all around us," said Peter Eisenhardt, the WISE project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and lead author of a recent paper in the Astronomical Journal on the Spitzer discoveries. "We might even find a cool brown dwarf that is closer to us than Proxima Centauri, the closest known star."

This artist's conception shows simulated data predicting the hundreds of failed stars, or brown dwarfs, that NASA's Wide-field Infrared Survey Explorer (WISE) is expected to add to the population of known stars in our solar neighborhood. Image credit: AMNH/UCB/NASA/JPL-Caltech

Brown dwarfs form like stars out of collapsing balls of gas and dust, but they are puny in comparison, never collecting enough mass to ignite nuclear fusion and shine with starlight. The smallest known brown dwarfs are about 5 to 10 times the mass of our planet Jupiter -- that's as massive as some known gas-giant planets around other stars. Brown dwarfs start out with a bit of internal heat left over from their formation, but with age, they cool down. The first confirmed brown dwarf was announced in 1995.

"Brown dwarfs are like planets in some ways, but they are in isolation," said astronomer Daniel Stern, co-author of the Spitzer paper at JPL. "This makes them exciting for astronomers -- they are the perfect laboratories to study bodies with planetary masses."

Most of the new brown dwarfs found by Spitzer are thought to belong to the coolest known class of brown dwarfs, called T dwarfs, which are defined as being less than about 1,500 Kelvin (2,240 degrees Fahrenheit). One of the objects appears to be so cold that it may even be a long-sought Y dwarf -- a proposed class of even colder stars. The T and Y classes are part of a larger system categorizing all stars; for example, the hottest, most massive stars are O stars; our sun is a G star.

"Models indicate there may be an entirely new class of stars out there, the Y dwarfs, that we haven't found yet," said co-author Davy Kirkpatrick, a co-author of the study and a member of the WISE science team at the California Institute of Technology, Pasadena, Calif. "If these elusive objects do exist, WISE will find them." Kirkpatrick is a world expert in brown dwarfs -- he came up with L, T and Y classifications for the cooler stars.

Kirkpatrick says that it's possible that WISE could find an icy, Neptune-sized or bigger object in the far reaches of our solar system -- thousands of times farther from the sun than Earth. There is some speculation amongst scientists that such a cool body, if it exists, could be a brown dwarf companion to our sun. This hypothetical object has been nicknamed "Nemesis."

"We are now calling the hypothetical brown dwarf Tyche instead, after the benevolent counterpart to Nemesis," said Kirkpatrick. "Although there is only limited evidence to suggest a large body in a wide, stable orbit around the sun, WISE should be able to find it, or rule it out altogether."

This image shows what astronomers think is one of the coldest brown dwarfs discovered so far (red dot in middle of frame). Image credit: NASA/JPL-Caltech

The 14 objects found by Spitzer are hundreds of light-years away -- too far away and faint for ground-based telescopes to see and confirm with a method called spectroscopy. But their presence implies that there are a hundred or more within only 25 light-years of our sun. Because WISE is looking everywhere, it will find these missing orbs, which will be close enough to confirm with spectroscopy. It's possible that WISE will even find more brown dwarfs within 25-light years of the sun than the number of stars known to exist in this space.

"WISE is going to transform our view of the solar neighborhood," said Eisenhardt. We'll be studying these new neighbors in minute detail -- they may contain the nearest planetary system to our own."

Other authors of the Spitzer paper are Roger Griffith and Amy Mainzer of JPL; Ned Wright, A.M. Ghez and Quinn Konopacky of UCLA; Matthew Ashby and Mark Brodwin of the Harvard-Smithsonian Center for Astrophysics, Cambridge; Mass., Michael Brown of Monash University, Australia; R.S. Bussmann of the University of Arizona, Tucson; Arjun Dey of National Optical Astronomy Observatory, Tucson, Ariz.; Eilat Glikman of Caltech; Anthony Gonzalez and David Vollbach of the University of Florida, Gainesville; and Shelley Wright of the University of California, Berkeley.

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

JPL manages the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer. More information about WISE is online at http://wise.astro.ucla.edu and http://www.nasa.gov/wise.

For more information visit http://www.nasa.gov/mission_pages/spitzer/news/spitzer20100624.html

NASA Releases Kepler Data on Potential Extrasolar Planets

PASADENA, Calif. -- NASA's Kepler Mission has released 43 days of science data on more than 156,000 stars. These stars are being monitored for subtle brightness changes as part of an ongoing search for Earth-like planets outside of our solar system.

Astronomers will use the new data to determine if orbiting planets are responsible for brightness variations in several hundred stars. These stars represent a full range of temperatures, sizes and ages. Many of them are stable, while others pulsate. Some show starspots, which are similar to sunspots, and a few produce flares that would sterilize their nearest planets.

Kepler, a space observatory, looks for the data signatures of planets by measuring tiny decreases in the brightness of stars when planets cross in front of, or transit, them. The size of the planet can be derived from the change in the star's brightness.

Artist's concept of Kepler in the distant solar system. Image credit: NASA/JPL-Caltech

The 28-member Kepler science team also is using ground-based telescopes and NASA's Hubble Space Telescope and Spitzer Space Telescope to perform follow-up observations on a specific set of 400 objects of interest. The star field that Kepler observes in the constellations Cygnus and Lyra can only be seen from ground-based observatories in spring through early fall. The data from these other observations will determine which of the candidates can be identified as planets. That data will be released to the scientific community in February 2011.

Without the additional information, candidates that are actual planets cannot be distinguished from false alarms, such as binary stars -- two stars that orbit each other. The size of the planetary candidates also can be only approximated until the size of the stars they orbit is determined from additional spectroscopic observations made by ground-based telescopes.

"I look forward to the scientific community analyzing the data and announcing new exoplanet results in the coming months," said Lia LaPiana, Kepler's program executive at NASA Headquarters in Washington.

"This is the most precise, nearly continuous, longest and largest data set of stellar photometry ever," said Kepler Deputy Principal Investigator David Koch of NASA's Ames Research Center in Moffett Field, Calif. "The results will only get better as the duration of the data set grows with time."

Kepler will continue conducting science operations until at least November 2012, searching for planets as small as Earth, including those that orbit stars in a warm, habitable zone where liquid water could exist on the surface of the planet. Since transits of planets in the habitable zone of solar-like stars occur about once a year and require three transits for verification, it is expected to take at least three years to locate and verify an Earth-size planet.

"The Kepler observations will tell us whether there are many stars with planets that could harbor life, or whether we might be alone in our galaxy," said the mission's science principal investigator, William Borucki of Ames.

Ames is responsible for the ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed the Kepler mission development. Ball Aerospace and Technologies Corp. in Boulder, Colo., developed the Kepler flight system, and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes the Kepler science data.

To see the science data, visit: http://archive.stsci.edu/kepler. For more information about the Kepler mission, visit: http://www.nasa.gov/kepler.

For more information visit http://www.nasa.gov/topics/universe/features/kepler20100615.html

NASA Helps in Upcoming Asteroid Mission Homecoming

The space and astronomy worlds have June 13 circled on the calendar.

That's when the Japan Aerospace Exploration Agency (JAXA) expects the sample return capsule of the agency's technology demonstrator spacecraft, Hayabusa, to boomerang back to Earth. The capsule, along with its mother ship, visited a near-Earth asteroid, Itokawa, five years ago and has logged about 2 billion kilometers (1.25 billion miles) since its launch in May 2003.

With the return of the Hayabusa capsule, targeted for June 13 at Australia's remote Woomera Test Range in South Australia, JAXA will have concluded a remarkable mission of exploration -- one in which NASA scientists and engineers are playing a contributing role.

"Hayabusa will be the first space mission to have made physical contact with an asteroid and returned to Earth," said Tommy Thompson, NASA's Hayabusa project manager from the Jet Propulsion Laboratory in Pasadena, Calif. "The mission and its team have faced and overcome several challenges over the past seven years. This round-trip journey is a significant space achievement and one which NASA is proud to be part of."

Launched May 9, 2003, from the Kagoshima Space Center, Uchinoura, Japan, Hayabusa was designed as a flying testbed. Its mission: to research several new engineering technologies necessary for returning planetary samples to Earth for further study. With Hayabusa, JAXA scientists and engineers hoped to obtain detailed information on electrical propulsion and autonomous navigation, as well as an asteroid sampler and sample reentry capsule.

The 510-kilogram (950-pound) Hayabusa spacecraft rendezvoused with asteroid Itokawa in September 2005. Over the next two-and-a-half months, the spacecraft made up-close and personal scientific observations of the asteroid's shape, terrain, surface altitude distribution, mineral composition, gravity, and the way it reflected the sun's rays. On Nov. 25 of that year, Hayabusa briefly touched down on the surface of Itokawa. That was only the second time in history a spacecraft descended to the surface of an asteroid (NASA's Near Earth Asteroid Rendezvous-Shoemaker spacecraft landed on asteroid Eros on Feb. 12, 2001). Hayabusa marked the first attempt to sample asteroid surface material.

The spacecraft departed Itokawa in January 2007. The road home for the technology demonstrator has been a long one, with several anomalies encountered along the way. But now the spacecraft is three days away from its home planet, and the Australian government, working closely with JAXA, has cleared the mission for landing. A team of Japanese and American navigators is guiding Hayabusa on the final leg of its journey. Together, they calculate the final trajectory correction maneuvers Hayabusa's ion propulsion system must perform for a successful homecoming.

"We have been collaborating with the JAXA navigators since the launch of the mission," said Shyam Bhaskaran, a member of JPL's Hayabusa navigation team. "We worked closely with them during the descents to the asteroid, and now are working together to guide the spacecraft back home."

To obtain the data they need, the navigation team frequently calls upon JAXA's tracking stations in Japan, as well as those of NASA's Deep Space Network, which has antennas at Goldstone, in California's Mojave Desert; near Madrid, Spain; and near Canberra, Australia. In addition, the stations provide mission planners with near-continuous communications with the spacecraft to keep them informed on spacecraft health.

This artist's concept depicts the Hayabusa spacecraft (left) and sample return capsule (right) entering the atmosphere over South Australia. Image credit: NASA/JPL

"Our task is to help advise JAXA on how to best get a spacecraft traveling at 12.2 kilometers per second (27,290 miles per hour) to intersect a very specific target point 200 kilometers (120 miles) above the Earth," said Bhaskaran. "Once that is done, and the heat shield of the sample return capsule starts glowing from atmospheric friction, our job is done."

While atmospheric entry may be the end of the line for the team that has plotted the spacecraft's every move for the past 2 billion kilometers, NASA's involvement continues for the craft's final 200 kilometers (120 miles), to the surface of the Australian Outback. A joint Japanese-U.S. team operating on the ground and in the air will monitor this most critical event to help retrieve the capsule and heat shield.

"This is the second highest velocity re-entry of a capsule in history," said Peter Jenniskens, a SETI Institute scientist at NASA's Ames Research Center in Moffett Field, Calif. "This extreme entry speed will result in high heating rates and thermal loads to the capsule's heat shield. Such manmade objects entering with interplanetary speed do not happen every day, and we hope to get a ringside seat to this one."

Jenniskens is leading an international team as it monitor the final plunge of Hayabusa to Earth using NASA's DC-8 airborne laboratory, which is managed and piloted by a crew from NASA's Dryden Flight Research Center, Edwards, Calif. The DC-8 flies above most clouds, allowing an unfettered line of sight for its instrument suite measuring the shock-heated gas and capsule surface radiation emitted by the re-entry fireball.

The data acquired by the high-flying team will help evaluate how thermal protection systems behave during these super-speedy spacecraft re-entries. This, in turn, will help engineers understand what a sample return capsule returning from Mars would undergo. The Hayabusa sample return capsule re-entry observation will be similar to earlier observations by the DC-8 team of NASA's Stardust capsule return, and the re-entry of the European Space Agency's ATV-1 ("Jules Verne") automated transfer vehicle.

Soon after the sample return capsule touches down on the ground, Hayabusa team members will retrieve it and transport it to JAXA's sample curatorial facility in Sagamihara, Japan. There, Japanese astromaterials scientists, assisted by two scientists from NASA and one from Australia, will perform a preliminary cataloging and analysis of the capsule's contents.

"This preliminary analysis follows the basic protocols used for Apollo moon rocks, Genesis and Stardust samples," said Mike Zolensky, a scientist at NASA's Astromaterials Research and Exploration Science Directorate at the Johnson Space Center, Houston. "If this capsule contains samples from the asteroid, we expect it will take a year to determine the primary characteristics of the samples, and learn how to best handle them. Then the samples will be distributed to scientists worldwide for more detailed analysis."

"The Japanese and NASA engineers and scientists involved in Hayabusa's return from asteroid Itokawa are proud of their collaboration and their joint accomplishments," said Thompson. "Certainly, any samples retrieved from Itokawa will provide exciting new insights to understanding the early history of the solar system. This will be the icing on the cake, as this mission has already taught us so much. "

For more information about the Hayabusa mission, visit:

http://www.isas.jaxa.jp/e/enterp/missions/hayabusa/index.shtml .

For more information visit http://www.nasa.gov/topics/solarsystem/features/hayabusa20100609.html

NASA's Dawn Spacecraft Fires Past Record for Speed Change

PASADENA, Calif. - Deep in the heart of the asteroid belt, on its way to the first of the belt's two most massive inhabitants, NASA's ion-propelled Dawn spacecraft has eclipsed the record for velocity change produced by a spacecraft's engines.

The previous standard-bearer for velocity change, NASA's Deep Space 1, also impelled by ion propulsion, was the first interplanetary spacecraft to use this technology. The Deep Space 1 record fell on Saturday, June 5, when the Dawn spacecraft's accumulated acceleration over the mission exceeded 4.3 kilometers per second (9,600 miles per hour).

"We are using this amazing ion-engine technology as a stepping-stone to orbit and explore two of the asteroid belt's most mysterious objects, Vesta and Ceres," said Robert Mase, Dawn project manager from NASA's Jet Propulsion Laboratory in Pasadena, Calif.

A spacecraft's change in velocity refers to its ability to change its path through space by using its own rocket engines. This measurement of change begins only after the spacecraft exits the last stage of the launch vehicle that hurled it into space.

To get to where it is in both the record books and the asteroid belt, the Dawn spacecraft had to fire its three engines - one at a time-- for a cumulative total of 620 days. In that time, it has used less than 165 kilograms (363 pounds) of xenon propellant. Over the course of its eight-plus-year mission, Dawn's three ion engines are expected to accumulate 2,000 days of operation -- 5.5 years of thrusting -- for a total change in velocity of more than 38,620 kilometers per hour (24,000 miles per hour).

NASA's Dawn spacecraft, illustrated in this artist's concept, is propelled by ion engines. Image credit: NASA/JPL

"I am delighted that it will be Dawn that surpasses DS1's record," said Marc Rayman, chief engineer for the Dawn mission and a previous project manager for Deep Space 1."It is a tribute to all those involved in the design and operations of this remarkable spacecraft."

At first glance, Dawn's pedal-to-the-metal performance is a not-so-inspiring 0-to-97 kilometers per hour (0-to-60 miles per hour) in four days. But due to its incredible efficiency, it expends only 37 ounces of xenon propellant during that time. Then take into consideration that after those four days of full-throttle thrusting, it will do another four days, and then another four. By the end of 12 days, the spacecraft will have increased its velocity by more than 290 kilometers per hour (180 miles per hour), with more days and weeks and months of continuous thrusting to come. In one year's time, Dawn's ion propulsion system can increase the spacecraft's speed by 8,850 kilometers per hour (5,500 miles per hour), while consuming the equivalent of only 16 gallons of fuel.

"This is a special moment for the spacecraft team," said Dawn's principal investigator, Chris Russell of the University of California Los Angeles. "In only 407 days, our minds will be on another set of records, the data records that Dawn will transmit when we enter Vesta orbit."

Dawn's 4.8-billion-kilometer (3-billion-mile) odyssey includes exploration of asteroid Vesta in 2011 and 2012, and the dwarf planet Ceres in 2015. These two icons of the asteroid belt have been witness to much of our solar system's history. By using the same set of instruments at two separate destinations, scientists can more accurately formulate comparisons and contrasts. Dawn's science instrument suite will measure shape, surface topography and tectonic history, elemental and mineral composition, as well as seek out water-bearing minerals. In addition, the way the Dawn spacecraft orbits both Vesta and Ceres will be used to measure the celestial bodies' masses and gravity fields.

While Dawn surpassed Deep Space 1's record for velocity change, Deep Space 1 will continue to reign as holder for the longest duration of powered spaceflight for another few months. Dawn is expected to take over that record on about August 10 of this year.

The Dawn mission to Vesta and Ceres is managed by JPL, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate, Washington. The University of California, Los Angeles, is responsible for overall Dawn mission science. Other scientific partners include Planetary Science Institute, Tucson, Ariz.; Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany; DLR Institute for Planetary Research, Berlin, Germany; Italian National Institute for Astrophysics, Rome; and the Italian Space Agency, Rome. Orbital Sciences Corporation of Dulles, Va., designed and built the Dawn spacecraft.

To learn more about Dawn and its mission to the asteroid belt, visit: http://www.nasa.gov/dawn

For more information visit http://www.nasa.gov/mission_pages/dawn/news/dawn20100607.html

Hubble Images Suggest Rogue Asteroid Smacked Jupiter

Without warning, a mystery object struck Jupiter on July 19, 2009, leaving a dark bruise the size of the Pacific Ocean. The spot first caught the eye of an amateur astronomer in Australia, and soon, observatories around the world, including NASA’s Hubble Space Telescope, were zeroing in on the unexpected blemish.

Astronomers had witnessed this kind of cosmic event before. Similar scars had been left behind during the course of a week in July 1994, when more than 20 pieces of Comet P/Shoemaker-Levy 9 (SL9) plunged into Jupiter’s atmosphere. The 2009 impact occurred during the same week, 15 years later.

Astronomers who compared Hubble images of both collisions say the culprit may have been an asteroid about 1,600 feet (500 meters) wide. The images, therefore, may show for the first time the immediate aftermath of an asteroid, rather than a comet, striking another planet.

The Jupiter bombardments reveal that the solar system is a rambunctious place, where unpredictable events may occur more frequently than first thought. Jupiter impacts were expected to occur every few hundred to few thousand years. Although there are surveys to catalogue asteroids, many small bodies may still go unnoticed and show up anytime to wreak havoc.

“This solitary event caught us by surprise, and we can only see the aftermath of the impact, but fortunately we do have the 1994 Hubble observations that captured the full range of impact phenomena, including the nature of the objects from pre-impact observations” says astronomer Heidi Hammel of the Space Science Institute in Boulder, Colo., leader of the Jupiter impact study.

These NASA Hubble Space Telescope snapshots reveal an impact scar on Jupiter fading from view over several months between July 2009 and November 2009. Credit: NASA, ESA, M. Wong, H. Hammel, I. de Pater, and the Jupiter Impact Team

In 2009 Hammel’s team snapped images of the debris field with Hubble’s recently installed Wide Field Camera 3 and newly repaired Advanced Camera for Surveys.

The analysis revealed key differences between the two collisions (in 1994 and 2009), providing clues to the 2009 event. Astronomers saw a distinct halo around the 1994 impact sites in Hubble ultraviolet (UV) images, evidence of fine dust arising from a comet-fragment strike. The UV images also showed a strong contrast between impact-generated debris and Jupiter’s clouds.

Hubble ultraviolet images of the 2009 impact showed no halo and also revealed that the site’s contrast faded rapidly. Both clues suggest a lack of lightweight particles, providing circumstantial evidence for an impact by a solid asteroid rather than a dusty comet.

The elongated shape of the recent impact site also differs from the 1994 strike, indicating that the 2009 object descended from a shallower angle than the SL9 fragments. The 2009 body also came from a different direction than the SL9 pieces.

Team member Agustín Sanchez-Lavéga of the University of the Basque Country in Bilbao, Spain, and colleagues performed an analysis of possible orbits that the 2009 impacting body could have taken to collide with Jupiter. Their work indicates the object probably came from the Hilda family of bodies, a secondary asteroid belt consisting of more than 1,100 asteroids orbiting near Jupiter.

The 2009 strike was equal to a few thousand standard nuclear bombs exploding, comparable to the blasts from the medium-sized fragments of SL9. The largest of those fragments created explosions that were many times more powerful than the world’s entire nuclear arsenal blowing up at once.

The recent impact underscores the important work performed by amateur astronomers. “This event beautifully illustrates how amateur and professional astronomers can work together,” notes Hammel.

Occasional dark spots have appeared on Jupiter throughout the history of sky watching. Observing records of the planet are filled with references to spots, including “white spots,” “peculiar spots,” and “well-defined spots.” Only a handful may have described possible Jupiter strikes.

In 1686, the Italian astronomer Giovanni Cassini reported a dark spot on Jupiter that was roughly the size of the largest SL9 impact. Nearly 150 years later, in 1834, British astronomer George Airy independently reported a dark feature in Jupiter’s southern belts that looked nearly four times as large as shadows cast on the planet by the Galilean moons. Crude telescopes prevented sky watchers from probing the nature of those spots.

The study by Hammel’s team appeared in the June 1 issue of The Astrophysical Journal Letters.

For images and more information about Jupiter, visit:
hubblesite.org/news/2010/16
nasa.gov/hubble

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

NASA's Webb Telescope Has 'Made It' to New York City!

The James Webb Space Telescope has finally made the "big time" at least according to the old Frank Sinatra song "New York, New York." The life-sized model of NASA's next generation space telescope is being set up in New York City's Battery Park for the 2010 World Science Festival, which runs June 1- June 6. The opening ceremony will be held in front of the model on June 1.

As the song goes, "if (the Webb telescope) can make it there, it'll make it anywhere" and scientists are hoping that it will safely arrive in its orbit one million miles from Earth.

"The World Science Festival is a great opportunity for people to get a look at, and learn more about, the future of astronomy from space," said Eric Smith, NASA's Webb Program Scientist. "The Webb telescope full scale model dramatically highlights how far the next generation of space telescopes will be from its predecessors. It’s unlike any telescope you’ve ever seen."

The Webb telescope full scale model lit up at night in Munich, Germany in 2009. Credit: EADS

The James Webb Space Telescope is the next-generation premier space observatory, exploring deep space phenomena from distant galaxies to nearby planets and stars. The telescope will give scientists clues about the formation of the universe and the evolution of our own solar system, from the first light after the Big Bang to the formation of star systems capable of supporting life on planets like Earth.

For six days in June, New York City residents can get a free look at the full-scale model of the Webb telescope as it sits on display in Battery Park. The model viewing hours run from Tuesday, June 1 from 9:00 a.m. to Sunday, June 6 at 9:00 p.m. EDT. The actual size model is highly detailed. It is constructed mainly of aluminum and steel, weighs 12,000 pounds, is approximately 80 feet long, 40 feet wide and 40 feet tall. It is as large as a tennis court. The model requires 2 trucks to ship it and assembly takes a crew of 12 approximately four days. The model will be lit up from its base so that night-time viewers can take in all the details.

The full-scale model of the James Webb Space Telescope was built by the prime contractor, Northrop Grumman, to provide a better understanding of the size, scale and complexity of this satellite.

Visitors will also be able to learn about what the Webb telescope is going to show scientists. They can play with interactive exhibits, watch videos about what the Webb will be exploring in the cosmos, and even ask a scientist about the telescope.

On Friday June 4, from 8-9:30 p.m. EDT, there will be a special event at the base of the full-sized model, called "From the City to the Stars," where scientists will talk about the possible discoveries that the Webb telescope could make.

The life-sized James Webb Space Telescope model sits in front of the Royal Hospital Kilmainham, in Dublin, Ireland. Credit: Richard Bent, Northrop Grumman Space Technology.

The event is also free and open to the public. Dr. John Mather, Nobel laureate and the Webb telescope’s senior project scientist; Dr. John Grunsfeld, astronaut, physicist and "chief repairman" of the Hubble Telescope and planetary astronomer Dr. Heidi Hammel will be at the event to talk about the discoveries anticipated from the Webb telescope. NASA Deputy Administrator Lori Garver will be a featured speaker at the Festival kick-off. She will share with the New York audience NASA’s strong commitment to continued scientific discovery, with missions like the Webb telescope, and talk about some of the other exciting endeavors on NASA’s new path forward.

Since 2005, the model has journeyed to Florida, Germany, Ireland and Washington, D.C. The actual Webb space telescope is going a lot further, about a million miles from Earth!

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

Hubble Finds a Star Eating a Planet

The hottest known planet in the Milky Way galaxy may also be its shortest-lived world. The doomed planet is being eaten by its parent star, according to observations made by a new instrument on NASA's Hubble Space Telescope, the Cosmic Origins Spectrograph (COS). The planet may only have another 10 million years left before it is completely devoured.

The planet, called WASP-12b, is so close to its sunlike star that it is superheated to nearly 2,800 degrees Fahrenheit and stretched into a football shape by enormous tidal forces. The atmosphere has ballooned to nearly three times Jupiter's radius and is spilling material onto the star. The planet is 40 percent more massive than Jupiter.

This effect of matter exchange between two stellar objects is commonly seen in close binary star systems, but this is the first time it has been seen so clearly for a planet.

"We see a huge cloud of material around the planet, which is escaping and will be captured by the star. We have identified chemical elements never before seen on planets outside our own solar system," says team leader Carole Haswell of The Open University in Great Britain.

Haswell and her science team's results were published in the May 10, 2010 issue of The Astrophysical Journal Letters.

A theoretical paper published in the science journal Nature last February by Shu-lin Li of the Department of Astronomy at the Peking University, Beijing, first predicted that the planet's surface would be distorted by the star's gravity, and that gravitational tidal forces make the interior so hot that it greatly expands the planet's outer atmosphere. Now Hubble has confirmed this prediction.

Artist's concept of the exoplanet WASP-12b. Credit: NASA/ESA/G. Bacon

WASP-12 is a yellow dwarf star located approximately 600 light-years away in the winter constellation Auriga. The exoplanet was discovered by the United Kingdom's Wide Area Search for Planets (WASP) in 2008. The automated survey looks for the periodic dimming of stars from planets passing in front of them, an effect called transiting. The hot planet is so close to the star it completes an orbit in 1.1 days.

The unprecedented ultraviolet (UV) sensitivity of COS enabled measurements of the dimming of the parent star's light as the planet passed in front of the star. These UV spectral observations showed that absorption lines from aluminum, tin, manganese, among other elements, became more pronounced as the planet transited the star, meaning that these elements exist in the planet's atmosphere as well as the star's. The fact the COS could detect these features on a planet offers strong evidence that the planet's atmosphere is greatly extended because it is so hot.

The UV spectroscopy was also used to calculate a light curve to precisely show just how much of the star's light is blocked out during transit. The depth of the light curve allowed the COS team to accurately calculate the planet's radius. They found that the UV-absorbing exosphere is much more extended than that of a normal planet that is 1.4 times Jupiter's mass. It is so extended that the planet's radius exceeds its Roche lobe, the gravitational boundary beyond which material would be lost forever from the planet's atmosphere.

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

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Central Peak of Bullialdus Crater

Nearly every square inch of the Moon is affected by impact craters, from micron-sized pits to gargantuan impact basins (like the 1100 km diameter Imbrium basin, which you can see with your naked eyes on a clear night). Lunar craters have a dizzying array of sizes and morphologies; this is because the size and the morphology of a crater depends on the size (and to some extent, the speed) of the impacting bolide.

The Moon is the best preserved and most accessible laboratory for understanding impact processes. Impacts are the most fundamental and important geologic process in the Solar System. On the Earth, which has been hit by impactors for over four billion years, erosion caused by wind and precipitation degrades impact craters, making them (relatively) hard to study. On the Moon, though, these craters are relatively well preserved.

Summit of the central peak of Bullialdus crater, a Constellation region of interest. LROC Narrow Angle Camera image M114098458LE, image is 500 m wide Credit: NASA/GSFC/Arizona State University

Complex craters are of particular interest. Complex craters have a well defined central peak and often a terraced rim; this central peak is brought up from great depths beneath the crater as the ground elastically rebounds after the shock and pressure of the bolide impact. These sorts of impacts happened on Earth, too - but the erosion caused by terrestrial weather removes all traces of their presence. On the Moon, though, complex impact structures are well-preserved, and the central peaks - which have brought up materials from great depth - offer us the easiest way to explore the composition of the Moon's lower crust and upper mantle, providing critical insights for planetary scientists trying to figure out how planets in this Solar System (and others, around other stars) form.

LROC Wide Angle Camera View of Bullialdus crater (60 km diameter). The approximate position of today's NAC featured image is highlighted with the white arrow. Credit: NASA/GSFC/Arizona State University

Today's featured image shows the summit of the central peak of Bullialdus crater, an exploration region of interest located in the western part of Mare Nubium. Spectroscopic observations of Bullialdus using terrestrial telescopes showed that Bullialdus is compositionally distinct from the surrounding region. Later studies using Clementine multispectral data indicated that there are several rock types exposed on the floor of the crater. Lunar scientists who have studied Bullialdus proposed that the impact excavated mafic materials from great depth. Lunar scientists need to discover what these mafic materials are - are they some type of exotic mare basalts? Rare highlands non-mare volcanic rocks? We don't know, and we must find out to fully understand the Moon.

The central peak of Bullialdus is about a kilometer high. Astronaut explorers will not only have to explore around the base, but probably also scale this small mountain to collect the diverse array of samples required to really answer this question.

For more information visit http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/20100513_bullialdus.html

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NASA Invites Public to Take Virtual Walk on Moon

More than 37 years after humans last walked on the moon, planetary scientists are inviting members of the public to return to the lunar surface as “virtual astronauts” to help answer important scientific questions.

No spacesuit or rocket ship is required -- all visitors need to do is go to www.moonzoo.org and be among the first to see the lunar surface in unprecedented detail. New high-resolution images, taken by NASA’s Lunar Reconnaissance Orbiter Camera (LROC), offer exciting clues to unveil or reveal the history of the moon and our solar system.

“We need Web users around the world to help us interpret these stunning new images of the lunar surface,” said Chris Lintott of Oxford University and chair of the Citizen Science Alliance. “If you only spend five minutes on the site counting craters you’ll be making a valuable contribution to science and, who knows, you might run across a Russian spacecraft.”

Screen capture of the Moon Zoo site.

Scientists are particularly interested in knowing how many craters appear in a particular region of the moon in order to determine the age and depth of the lunar surface (regolith). Fresh craters left by recent impacts provide clues about the potential risks from meteor strikes on the moon and on Earth.

“We hope to address key questions about the impact bombardment history of the moon and discover sites of geological interest that have never been seen before,” said Katherine Joy of the Lunar and Planetary Institute and a Moon Zoo science team member.

NASA Lunar Science Institute (NLSI) scientists are contributing to the Moon Zoo efforts by providing science expertise. NLSI is also providing educational content and supporting outreach goals of the project.

The Moon Zoo makes use of images, such as this one showing the Apollo 11 landing site, from the LRO Camera. Credit: NASA/Goddard/Arizona State University

“The NASA Lunar Science Institute is very excited to be involved with Moon Zoo and support lunar citizen science,” said David Morrison, NLSI director. “Science and public outreach are cornerstones of our Institute; Moon Zoo will contribute to the accomplishment of important science, while being a major step forward in participatory exploration.”

For more information visit http://www.nasa.gov/mission_pages/LRO/news/moon-zoo.html

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Intra-Crater Structure in NW Hellas Basin, Mars

This subimage from an observation by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter covers a small portion of the northwest quadrant of Hellas Basin, or Hellas Planitia, on southern Mars. With a diameter of about 2,200 kilometers (about 1,400 miles) and a depth reaching the lowest elevations on Mars, Hellas is one of the largest impact craters in the solar system.

This area of Hellas Basin has a number of unusual features which are thought to be quite old because of the high crater density. Here a crater inside Hellas has been filled with material. This may be related to volcanic activity on the northwestern rim of Hellas.

However, it might also be related to water and water ice. There is evidence elsewhere that the ground here is ice-rich. HiRISE is being used to investigate this in more detail when Hellas Basin is free from atmospheric dust.

This image is a portion of the HiRISE observation catalogued as ESP_017196_1455, taken on March 28, 2010, and centered at 33.95 degrees south latitude, 48.50 degrees east longitude. Other image products from this observation are available at http://hirise.lpl.arizona.edu/ESP_017196_1455.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace & Technologies Corp., Boulder, Colo..

Image Credit: NASA/JPL-Caltech/University of Arizona/International Research School of Planetary Sciences

For more information visit http://www.nasa.gov/mission_pages/MRO/multimedia/pia13097.html

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Scientists Say Ice Lurks in Asteroid's Cold Heart

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

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

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

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

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

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

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

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

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

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

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

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NASA's Swift Catches 500th Gamma-ray Burst

In its first five years in orbit, NASA's Swift satellite has given astronomers more than they could have hoped for. Its discoveries range from a nearby nascent supernova to a blast so far away that it happened when our universe was only 5 percent of its present age.

Swift primarily studies gamma-ray bursts (GRBs) -- the biggest and most mysterious explosions in the cosmos. On April 13, the spacecraft's "burst-o-meter" cataloged its 500th GRB.

"On the one hand, it's just a number, but on the other it is a remarkable milestone," said Neil Gehrels, Swift's lead researcher at Goddard Space Flight Center in Greenbelt, Md. "Each burst has turned over a new piece of the puzzle and a clearer picture is emerging."

"Over five years and 500 bursts, Swift has fulfilled every significant promise of its mission and, in addition, brought a wealth of surprises," noted Derek Fox, a Swift team member at Penn State in University Park, Pa.

Watch: Five years of Swift-discovered gamma-ray bursts.
Credit: NASA/Goddard Space Flight Center/Swift

Burst 500, officially known as GRB 100413B, exploded in constellation Cassiopeia as a long burst, a type usually associated with the death of a massive star. It wasn't detected in on-board analysis of data from the spacecraft's Burst Alert Telescope (BAT), which was interrupted 18 seconds after the burst as Swift slewed to a pre-planned target.

Instead, GRB 100413B came to light when David Palmer, an astrophysicist at Los Alamos National Laboratory in New Mexico, later analyzed the data. "The BAT team regularly digs through the data once it comes to the ground and finds weak bursts like this one that take a bit of special care," said Goddard's Judith Racusin, who coordinated burst observations that day.

Summaries of other notable bursts in Swift's storied career are listed below.

This all-sky map shows the locations of Swift's 500 gamma-ray bursts, color coded by the year in which they occurred. In the background, an infrared image shows the location of our galaxy and its largest satellites. Credit: NASA/Swift/Francis Reddy

Swift's main job is to quickly localize each gamma-ray burst, report its position so that others can immediately conduct follow-up observations, and then study the burst using its X-ray and Ultraviolet/Optical telescopes. But it does much more, including ultraviolet studies of exploding stars, monitoring black holes and neutron stars for surges of high-energy radiation, and carrying out a long-term X-ray survey of the entire sky.

The spacecraft rocketed into orbit in November 2004. Managed by NASA's Goddard Space Flight Center, Swift was built and is operated in collaboration with Penn State, the Los Alamos National Laboratory in New Mexico, and General Dynamics of Gilbert, Ariz. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, with additional collaborators in Germany and Japan.

Origins

Because gamma rays are the highest-energy form of light, the brief but brilliant blasts represent a colossal energy release. Gamma-ray bursts were discovered in 1967 by unclassified military satellites designed to look for clandestine nuclear tests. The first observations required extensive analysis to be sure that the bursts were truly originating beyond the solar system, and they weren't published until 1973.

In binary systems containing neutron stars, the emission of gravitational radiation gradually brings the objects closer together. This animation shows such a system after about a billion years, when two equal-mass neutron stars whirl around each other 60,000 times a minute. The stars merge in a few milliseconds, sending out a pulse of gravitational waves and creating a short gamma-ray burst. Credit: NASA/Swift/Dana Berry

Over the following years, astronomers learned that sufficiently sensitive instruments could detect about two bursts per day, on average, somewhere in the sky. Of those twice-daily GRBs, Swift's Burst Alert Telescope snares about one in eight for detailed study.

According to Lorella Angelini, a Goddard astrophysicist now developing a comprehensive burst database, the number of recorded GRBs is approaching 6,000. Yet if one considers only bursts with measured distances, Swift's share of the total is a whopping 75 percent.

An earlier NASA satellite, the Compton Gamma Ray Observatory, showed that bursts come in long and short varieties, with long bursts (those lasting longer than two seconds) outnumbering short bursts three to one. Compton also showed that bursts occur randomly and evenly over the sky. Maps of GRB distribution bear no hint of our galaxy's structure. This means that they are extremely far away — and all the more powerful.

Across the universe

A key breakthrough in understanding GRBs came from the Italian-Dutch satellite Beppo-SAX, which in 1997 provided the first precise burst positions. It later discovered lingering X-ray emission -- dubbed "afterglows" -- at burst locations. Observatories on the ground quickly discovered afterglows in visible light, which provided information that confirmed the burst's enormous distances. Astronomers now regularly study afterglows across the electromagnetic spectrum.

Most of the time, the hard task of measuring burst distances falls to ground-based observatories, which can target a burst's location with telescopes far larger than the Ultraviolet/Optical Telescope aboard Swift.

"Getting on the afterglows quickly with large ground-based telescopes remains a key element in understanding GRBs," said Fox, whose research focuses on follow-up observations. "It's this synergy between Swift and ground observatories that has really moved the ball forward, especially for short bursts."

And the farther the burst, the more important rapid ground follow-up becomes. At distances greater than about 12 billion light-years, gas clouds block ultraviolet wavelengths before they can reach Earth, and all optical light becomes shifted into infrared wavelengths only detectable by specially-equipped ground-based telescopes. Astronomers scramble to detect afterglow from new bursts as soon as they can.

"Thanks to such efforts, we know Swift has seen GRBs as close as about 100 million light-years and as far away as 13 billion light-years," adds Gehrels. Put another way, Swift sees gamma-ray bursts over a span of time equivalent to about 95 percent of the universe's age.

The long and the short of GRBs

By the time Swift launched, mounting evidence already pointed to the deaths of massive stars as the source of most long GRBs -- a scenario that still stands. When such a star runs out of fuel, its core collapses and likely forms a black hole surrounded by a dense hot disk of gas called an accretion disk. Somehow, the black hole diverts part of the infalling matter into a pair of high-energy jets that tear through the collapsing star.

The jets move so fast -- upwards of 99.9 percent the speed of light -- that collisions within them produce gamma rays. As the jet breaches the star's surface, a gamma-ray burst is born. The jet continues on, later striking gas beyond the star to produce afterglows.

Short bursts, however, proved much harder to pin down. "We didn't know their most basic properties," notes Ehud Nakar, an astrophysicist at Tel Aviv University in Israel. "We knew so little we weren't even sure that short GRBs were a unique astrophysical phenomenon."

It turns out they are. "Long GRBs originate from the collapse of stars just millions of years old, but the objects that give rise to some short GRBs reach ages of billions of years before exploding," Nakar adds.

The emerging picture is that short GRBs arise when two compact objects -- either a pair of neutron stars or a neutron star and a black hole -- collide and merge. These objects, which are the crushed cores of exploded stars, pack more mass than the sun into volumes just a few miles across. For those bound in a binary system, Einstein's relativity seals their fate.

According to Einstein, massive orbiting objects give off a type of energy called gravitational radiation. Although no one has yet detected these waves, astronomers have observed an effect predicted by this energy loss -- the slowly shrinking orbits of binary neutron stars. Over billions of years, the stellar cinders grow ever closer and finally merge in an event that unleashes titanic energies and creates a short GRB.

Gamma-ray bursts longer than two seconds are caused by the collapse of a rap-idly rotating massive star at the end of its life. As the star collapses, jets of parti-cles and gamma radiation produced by a newborn black hole blast in opposite directions from the stellar core. Credit: NASA/Swift/Cruz deWilde

But Nakar thinks the full picture still eludes astronomers. "So far, the data favor merging neutron stars, and that is certainly the most popular idea, but other scenarios remain possible. We still do not know the origin of short GRBs."

Thanks mainly to burst identifications from Swift and the afterglow observations they make possible, scientists now have details on dozens of short bursts and their afterglows. "We're now beginning to understand the home galaxies of short GRBs," Fox said.

Over the past five years, Swift has delivered a great deal of revolutionary science. But its career isn't over yet -- and with a little luck, there will be much more to come.

Swift GRB highlights

April 13, 2010: NASA's Swift discovers its 500th burst. GRB 100413B is a long burst in the constellation Cassiopeia.

April 23, 2009: GRB 090423 in Leo holds the record for the farthest burst yet known -- 13.04 billion light-years away. "The burst is beyond the farthest confirmed galaxies and quasars, making it the most distant object we know in the universe today," Fox said. This find validates models suggesting that galaxy and star formation were well under way in the universe's first billion years and that some early stars died as bursts.

March 19, 2008: GRB 080319B, in Boötes, is truly extraordinary. It produces enough light to be seen briefly with the unaided eye, cresting at visual magnitude 5.3 despite occurring 7.5 billion light-years away -- or more than halfway across the visible universe. Scientists conclude that one of its particle jets appears to have been aimed squarely at Earth.

July 14, 2007: GRB 070714B explodes in Taurus. Afterglow observations indicate a distance of 7.3 billion light-years, making this one of the farthest short bursts to date.

Feb. 18, 2006: GRB 060218 explodes in Aries 450 million light-years away -- in our back yard, cosmically speaking. Although faint, the burst emits detectable gamma rays for more than 40 minutes and detectable optical and X-ray emission lasts more than 10 days. The event is a hybrid, showing characteristics of both a GRB and a supernova, and leads to the best observations yet exploring connections between these phenomena.

Sept. 4, 2005: At a distance of 12.77 billion light-years, GRB 050904, located in Pisces, is the farthest-known GRB at the time, the first of many such Swift records.

May 9, 2005: GRB 050509B, in Coma Berenices, erupts with a flash of gamma-rays that lasts just 0.03 second. Swift turns to the burst fast enough to detect 11 X-ray photons, making this the first short burst with a detected afterglow.

Dec. 17, 2004: Swift's first burst, in Crater, is eight-second-long GRB 041217.

For more information visit http://www.nasa.gov/mission_pages/swift/bursts/500th.html

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