בדיחות על חמותי (האתר הזה)
Tuesday, November 30, 2010
Saturday, November 27, 2010
Don't ask my way, I dont know
Sunday, November 21, 2010
Thursday, November 18, 2010
Imagine the kind of family you might see in a modern American sitcom
Imagine the kind of family you might see in a modern American sitcom: loving parents trying to maintain a family unit with a teenager engrossed in text messaging, a college-aged child who is always chatting online, and various wacky relatives who spend their days sending "funny" emails to the family.
This is an admittedly exaggerated stereotype but one we see every day in movies, TV and advertising because most of us can relate to parts of it. Between mobile devices and the Internet we can be more connected today than ever before, but there is still a feeling that the technology can also act as a barrier between us. When I want to share with someone it should be as simple as deciding who I want to share with and what I want to say. It should feel more like a human conversation.
How to get links from the usa gov web site
Linking Policy
Evaluation Criteria
The USA.gov staff evaluates all suggested links using the following criteria:- Is the recommended website an official government-owned or supported website?
- Does the recommended website provide official government information or services?
- Does the recommended website complement existing information, products and services on USA.gov?
- Is the recommended website accessible and applicable to a wide audience?
- Is the recommended website's content relevant, useful and authoritative for citizens, businesses and/or government officials?
- Does the recommended website's information appear to be accurate and current?
- Is the recommended website's approach to the privacy of personal information consistent with the government's privacy and security policies?
- Is the recommended website "user-friendly?"
- Does the recommended website meet one or more of the following "highly desirable" criteria?
- The website crosses agency or intergovernmental boundaries (e.g., students.gov, fedforms.gov and nutrition.gov);
- The website enables citizens, businesses and/or government officials to conduct transactions online (e.g., buying stamps or coins, replacing Medicare cards, and filing taxes);
- The website provides citizens, businesses and/or government officials with the information they need to interact directly with government organizations (e.g., clearly available telephone numbers, street addresses, e-mail addresses and instructions);
- The website provides citizens with information about service performance (e.g., Nursing Home Compare, AirNow and Ontime Airline Statistics); and/or
- The website provides community-level information and services (e.g., MapStats, post office locators, Social Security Office locators, National Park Service Guides and veterans' facilities).
Monday, November 15, 2010
space blog
Sunday, November 14, 2010
Oh Snap, NASA and LEGO Join Forces
LEGO bricks aren't just for kids, and they aren't just for Earth, either.
Astronauts on board the International Space Station will build small model spacecraft and working objects in orbit and share the experience with schoolchildren watching on Earth.
The students will build some of the same things in their own classrooms and see firsthand how differently objects behave in space, where there is practically no gravity, compared to the familiar world of Earth.
The project is one of the first steps in a three-year partnership between NASA and the Denmark-based The LEGO Group , maker of the ubiquitous plastic bricks that have been covering children's playroom floors for decades.
"We're going to use the classroom of space, the International Space Station, to inspire the next generation," said Leland Melvin, associate administrator for NASA Education and a former astronaut. Melvin flew two shuttle flights, spending time at the station during both missions. He joined LEGO officials Nov. 1 at NASA's Kennedy Space Center in Florida to announce the partnership.
Two small LEGO shuttles are packed inside Discovery for the STS-133 launch to promote the new partnership. They are expected to stay in their lockers, but astronauts may pull them out during the mission if they have time, said Debbie Biggs, an education specialist for International Space Station National Lab Education Projects.
NASA's fundamental goal is to use the partnership to inspire children to learn about science, technical fields, engineering and math. Known as STEM education, the focus has been a priority for the agency throughout this year's "Summer of Innovation."
Stephan Turnipseed, president of LEGO Education North America, said LEGO is the right partner because the bricks encourage kids to develop their inner engineer.
"Children think with their hands," Turnipseed said.
Astronaut Dan Tani, a veteran shuttle flier and station resident, agreed.
"LEGO taught me a lot of things about how things are built, what makes sense in terms of structure," said Tani, who brought his daughter to the LEGO activity tent. "I don't think I'd have been as good an engineer if it had not been for things like LEGO and construction kinds of toys."
There were plenty of children who thought so, too. Visiting LEGO's activity tent at one of the launch viewing sites at Kennedy on Wednesday, kids took to 1 ton of bricks and specialized pieces with barely any instructions. They quickly constructed spacecraft of all shapes, some small with launch facilities, others large replicas of the space shuttle. Some made a run at imagining colonies on the moon or Mars.
"You can make anything you want," said Tanner, a nine-year-old who has been building LEGO sets for years.
Melvin and Turnipseed were delighted with the kids' enthusiasm. They even joined in the building.
"This is showing what happens when we give kids a challenge, give them a tool that allows them to express their response to that challenge, their ideas," Turnipseed said.
LEGO and NASA still are working on lesson plans for students that will coincide with the work the astronauts perform in space, Biggs said. Some of the plans may even have the students challenge the astronaut to see who can build something quicker.
Astronaut Cady Coleman, in training for a mission to the International Space Station later this year, is slated to be the first astronaut enlisted to build LEGO objects in space.
Space shuttle Endeavour will carry nine specialized kits to the station in February during the STS-134 mission. Working with them inside a see-through glove box so the small pieces don't get lost in the station, Coleman will assemble LEGO blocks into models and working machines.
She already is practicing with some of the kits with her son and even picking up tips from other kids.
Melvin said the LEGO partnership is crucial for NASA's education mission because the blocks invite children to think, basically, like engineers. After all, building with the toys means deciding what kind of shape to make, what combination of blocks together make that shape the best and what can the thing do when it's finished. They also come up with designs that will be stronger depending on how the bricks are aligned with each other.
LEGO also is releasing four kits to the public based on NASA spacecraft and missions. Rather than being a part of a line of science fiction or fantasy toy kits, though, the NASA sets are being marketed as part of the company's "CITY" line, which calls on kids to build things that are part of everyday life.
"We believe that space, that space exploration, the fact that we have satellites in the air, it is a part of everyday life," Turnipseed said. "The children get it, they understand the importance of what we're doing."
"Space is permeated into everything we do," Melvin said.
For more information visit http://www.nasa.gov/mission_pages/shuttle/behindscenes/lego.html
Astronauts on board the International Space Station will build small model spacecraft and working objects in orbit and share the experience with schoolchildren watching on Earth.
The students will build some of the same things in their own classrooms and see firsthand how differently objects behave in space, where there is practically no gravity, compared to the familiar world of Earth.
The project is one of the first steps in a three-year partnership between NASA and the Denmark-based The LEGO Group , maker of the ubiquitous plastic bricks that have been covering children's playroom floors for decades.
"We're going to use the classroom of space, the International Space Station, to inspire the next generation," said Leland Melvin, associate administrator for NASA Education and a former astronaut. Melvin flew two shuttle flights, spending time at the station during both missions. He joined LEGO officials Nov. 1 at NASA's Kennedy Space Center in Florida to announce the partnership.
Two small LEGO shuttles are packed inside Discovery for the STS-133 launch to promote the new partnership. They are expected to stay in their lockers, but astronauts may pull them out during the mission if they have time, said Debbie Biggs, an education specialist for International Space Station National Lab Education Projects.
NASA's fundamental goal is to use the partnership to inspire children to learn about science, technical fields, engineering and math. Known as STEM education, the focus has been a priority for the agency throughout this year's "Summer of Innovation."
Stephan Turnipseed, president of LEGO Education North America, said LEGO is the right partner because the bricks encourage kids to develop their inner engineer.
"Children think with their hands," Turnipseed said.
Astronaut Dan Tani, a veteran shuttle flier and station resident, agreed.
"LEGO taught me a lot of things about how things are built, what makes sense in terms of structure," said Tani, who brought his daughter to the LEGO activity tent. "I don't think I'd have been as good an engineer if it had not been for things like LEGO and construction kinds of toys."
There were plenty of children who thought so, too. Visiting LEGO's activity tent at one of the launch viewing sites at Kennedy on Wednesday, kids took to 1 ton of bricks and specialized pieces with barely any instructions. They quickly constructed spacecraft of all shapes, some small with launch facilities, others large replicas of the space shuttle. Some made a run at imagining colonies on the moon or Mars.
"You can make anything you want," said Tanner, a nine-year-old who has been building LEGO sets for years.
Melvin and Turnipseed were delighted with the kids' enthusiasm. They even joined in the building.
"This is showing what happens when we give kids a challenge, give them a tool that allows them to express their response to that challenge, their ideas," Turnipseed said.
LEGO and NASA still are working on lesson plans for students that will coincide with the work the astronauts perform in space, Biggs said. Some of the plans may even have the students challenge the astronaut to see who can build something quicker.
Astronaut Cady Coleman, in training for a mission to the International Space Station later this year, is slated to be the first astronaut enlisted to build LEGO objects in space.
Space shuttle Endeavour will carry nine specialized kits to the station in February during the STS-134 mission. Working with them inside a see-through glove box so the small pieces don't get lost in the station, Coleman will assemble LEGO blocks into models and working machines.
She already is practicing with some of the kits with her son and even picking up tips from other kids.
Melvin said the LEGO partnership is crucial for NASA's education mission because the blocks invite children to think, basically, like engineers. After all, building with the toys means deciding what kind of shape to make, what combination of blocks together make that shape the best and what can the thing do when it's finished. They also come up with designs that will be stronger depending on how the bricks are aligned with each other.
LEGO also is releasing four kits to the public based on NASA spacecraft and missions. Rather than being a part of a line of science fiction or fantasy toy kits, though, the NASA sets are being marketed as part of the company's "CITY" line, which calls on kids to build things that are part of everyday life.
"We believe that space, that space exploration, the fact that we have satellites in the air, it is a part of everyday life," Turnipseed said. "The children get it, they understand the importance of what we're doing."
"Space is permeated into everything we do," Melvin said.
For more information visit http://www.nasa.gov/mission_pages/shuttle/behindscenes/lego.html
Friday, November 12, 2010
Detailed Dark Matter Map Yields Clues to Galaxy Cluster Growth
Astronomers using NASA's Hubble Space Telescope took advantage of a giant cosmic magnifying glass to create one of the sharpest and most detailed maps of dark matter in the universe. Dark matter is an invisible and unknown substance that makes up the bulk of the universe's mass.
The new dark matter observations may yield new insights into the role of dark energy in the universe's early formative years. The result suggests that galaxy clusters may have formed earlier than expected, before the push of dark energy inhibited their growth. A mysterious property of space, dark energy fights against the gravitational pull of dark matter. Dark energy pushes galaxies apart from one another by stretching the space between them, thereby suppressing the formation of giant structures called galaxy clusters. One way astronomers can probe this primeval tug-of-war is through mapping the distribution of dark matter in clusters.
A team led by Dan Coe at NASA's Jet Propulsion Laboratory in Pasadena, Calif., used Hubble's Advanced Camera for Surveys to chart the invisible matter in the massive galaxy cluster Abell 1689, located 2.2 billion light-years away. The cluster's gravity, the majority of which comes from dark matter, acts like a cosmic magnifying glass, bending and amplifying the light from distant galaxies behind it. This effect, called gravitational lensing, produces multiple, warped, and greatly magnified images of those galaxies, like the view in a funhouse mirror. By studying the distorted images, astronomers estimated the amount of dark matter within the cluster. If the cluster's gravity only came from the visible galaxies, the lensing distortions would be much weaker.
Based on their higher-resolution mass map, Coe and his collaborators confirm previous results showing that the core of Abell 1689 is much denser in dark matter than expected for a cluster of its size, based on computer simulations of structure growth. Abell 1689 joins a handful of other well-studied clusters found to have similarly dense cores. The finding is surprising, because the push of dark energy early in the universe's history would have stunted the growth of all galaxy clusters.
"Galaxy clusters, therefore, would had to have started forming billions of years earlier in order to build up to the numbers we see today," Coe explains. "At earlier times, the universe was smaller and more densely packed with dark matter. Abell 1689 appears to have been well fed at birth by the dense matter surrounding it in the early universe. The cluster has carried this bulk with it through its adult life to appear as we observe it today."
Mapping the Invisible
Abell 1689 is among the most powerful gravitational lensing clusters ever observed. Coe's observations, combined with previous studies, yielded 135 multiple images of 42 background galaxies.
"The lensed images are like a big puzzle," Coe says. "Here we have figured out, for the first time, a way to arrange the mass of Abell 1689 such that it lenses all of these background galaxies to their observed positions." Coe used this information to produce a higher-resolution map of the cluster's dark matter distribution than was possible before.
Coe teamed with mathematician Edward Fuselier, who, at the time, was at the United States Military Academy at West Point, to devise a new technique to calculate the new map. "Thanks, in large part, to Eddie's contributions, we have finally `cracked the code' of gravitational lensing. Other methods are based on making a series of guesses as to what the mass map is, and then astronomers find the one that best fits the data. Using our method, we can obtain, directly from the data, a mass map that gives a perfect fit."
Astronomers are planning to study more clusters to confirm the possible influence of dark energy. A major Hubble program that will analyze dark matter in gigantic galaxy clusters is the Cluster Lensing and Supernova survey with Hubble (CLASH). In this survey, the telescope will study 25 clusters for a total of one month over the next three years. The CLASH clusters were selected because of their strong X-ray emission, indicating they contain large quantities of hot gas. This abundance means the clusters are extremely massive. By observing these clusters, astronomers will map the dark matter distributions and look for more conclusive evidence of early cluster formation, and possibly early dark energy.
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/dark-matter-map.html
The new dark matter observations may yield new insights into the role of dark energy in the universe's early formative years. The result suggests that galaxy clusters may have formed earlier than expected, before the push of dark energy inhibited their growth. A mysterious property of space, dark energy fights against the gravitational pull of dark matter. Dark energy pushes galaxies apart from one another by stretching the space between them, thereby suppressing the formation of giant structures called galaxy clusters. One way astronomers can probe this primeval tug-of-war is through mapping the distribution of dark matter in clusters.
A team led by Dan Coe at NASA's Jet Propulsion Laboratory in Pasadena, Calif., used Hubble's Advanced Camera for Surveys to chart the invisible matter in the massive galaxy cluster Abell 1689, located 2.2 billion light-years away. The cluster's gravity, the majority of which comes from dark matter, acts like a cosmic magnifying glass, bending and amplifying the light from distant galaxies behind it. This effect, called gravitational lensing, produces multiple, warped, and greatly magnified images of those galaxies, like the view in a funhouse mirror. By studying the distorted images, astronomers estimated the amount of dark matter within the cluster. If the cluster's gravity only came from the visible galaxies, the lensing distortions would be much weaker.
Based on their higher-resolution mass map, Coe and his collaborators confirm previous results showing that the core of Abell 1689 is much denser in dark matter than expected for a cluster of its size, based on computer simulations of structure growth. Abell 1689 joins a handful of other well-studied clusters found to have similarly dense cores. The finding is surprising, because the push of dark energy early in the universe's history would have stunted the growth of all galaxy clusters.
"Galaxy clusters, therefore, would had to have started forming billions of years earlier in order to build up to the numbers we see today," Coe explains. "At earlier times, the universe was smaller and more densely packed with dark matter. Abell 1689 appears to have been well fed at birth by the dense matter surrounding it in the early universe. The cluster has carried this bulk with it through its adult life to appear as we observe it today."
Mapping the Invisible
Abell 1689 is among the most powerful gravitational lensing clusters ever observed. Coe's observations, combined with previous studies, yielded 135 multiple images of 42 background galaxies.
"The lensed images are like a big puzzle," Coe says. "Here we have figured out, for the first time, a way to arrange the mass of Abell 1689 such that it lenses all of these background galaxies to their observed positions." Coe used this information to produce a higher-resolution map of the cluster's dark matter distribution than was possible before.
Coe teamed with mathematician Edward Fuselier, who, at the time, was at the United States Military Academy at West Point, to devise a new technique to calculate the new map. "Thanks, in large part, to Eddie's contributions, we have finally `cracked the code' of gravitational lensing. Other methods are based on making a series of guesses as to what the mass map is, and then astronomers find the one that best fits the data. Using our method, we can obtain, directly from the data, a mass map that gives a perfect fit."
Astronomers are planning to study more clusters to confirm the possible influence of dark energy. A major Hubble program that will analyze dark matter in gigantic galaxy clusters is the Cluster Lensing and Supernova survey with Hubble (CLASH). In this survey, the telescope will study 25 clusters for a total of one month over the next three years. The CLASH clusters were selected because of their strong X-ray emission, indicating they contain large quantities of hot gas. This abundance means the clusters are extremely massive. By observing these clusters, astronomers will map the dark matter distributions and look for more conclusive evidence of early cluster formation, and possibly early dark energy.
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/dark-matter-map.html
Thursday, November 11, 2010
Saturn Then and Now: 30 Years Since Voyager Visit
Ed Stone, project scientist for NASA's Voyager mission, remembers the first time he saw the kinks in one of Saturn's narrowest rings. It was the day the Voyager 1 spacecraft made its closest approach to the giant ringed planet, 30 years ago. Scientists were gathering in front of television monitors and in one another's offices every day during this heady period to pore over the bewildering images and other data streaming down to NASA's Jet Propulsion Laboratory in Pasadena, Calif.
Stone drew a crude sketch of this scalloped, multi-stranded ring, known as the F ring, in his notebook, but with no explanation next to it. The innumerable particles comprising the broad rings are in near-circular orbits about Saturn. So, it was a surprise to find that the F ring, discovered just a year before by NASA's Pioneer 11 spacecraft, had clumps and wayward kinks. What could have created such a pattern?
"It was clear Voyager was showing us something different at Saturn," said Stone, now based at the California Institute of Technology in Pasadena. "Over and over, the spacecraft revealed so many unexpected things that it often took days, months and even years to figure them out."
The F ring curiosity was only one of many strange phenomena discovered in the Voyager close encounters with Saturn, which occurred on Nov. 12, 1980, for Voyager 1, and Aug. 25, 1981, for Voyager 2. The Voyager encounters were responsible for finding six small moons and revealing the half-young, half-old terrain of Enceladus that had to point to some kind of geological activity.
Images from the two encounters also exposed individual storms roiling the planet's atmosphere, which did not show up at all in data from Earth-based telescopes. Scientists used Voyager data to resolve a debate about whether Titan had a thick or thin atmosphere, finding that Titan was shrouded in a thick haze of hydrocarbons in a nitrogen-rich atmosphere. The finding led scientists to predict there could be seas of liquid methane and ethane on Titan's surface.
"When I look back, I realize how little we actually knew about the solar system before Voyager," Stone added. "We discovered things we didn't know were there to be discovered, time after time."
In fact, the Voyager encounters sparked so many new questions that another spacecraft, NASA's Cassini, was sent to probe those mysteries. While Voyager 1 got to within about 126,000 kilometers (78,300 miles) above Saturn's cloud tops, and Voyager 2 approached as close as about 100,800 kilometers (62,600 miles), Cassini has dipped to this altitude and somewhat lower in its orbits around Saturn since 2004.
Because of Cassini's extended journey around Saturn, scientists have found explanations for many of the mysteries first seen by Voyager. Cassini has uncovered a mechanism to explain the new terrain on Enceladus – tiger stripe fissures with jets of water vapor and organic particles. It revealed that Titan indeed does have stable lakes of liquid hydrocarbons on its surface and showed just how similar to Earth that moon really is. Data from Cassini have also resolved how two small moons discovered by Voyager – Prometheus and Pandora – tug on the F ring to create its kinked shape and wakes that form snowballs.
"Cassini is indebted to Voyager for its many fascinating discoveries and for paving the way for Cassini," said Linda Spilker, Cassini project scientist at JPL, who started her career working on Voyager from 1977 to 1989. "On Cassini, we still compare our data to Voyager's and proudly build on Voyager's heritage."
But Voyager left a few mysteries that Cassini has not yet solved. For instance, scientists first spotted a hexagonal weather pattern when they stitched together Voyager images of Saturn's north pole. Cassini has obtained higher-resolution pictures of the hexagon – which tells scientists it's a remarkably stable wave in one of the jet streams that remains 30 years later – but scientists are still not sure what forces maintain the hexagon.
Even more perplexing are the somewhat wedge-shaped, transient clouds of tiny particles that Voyager discovered orbiting in Saturn's B ring. Scientists dubbed them "spokes" because they looked like bicycle spokes. Cassini scientists have been searching for them since the spacecraft first arrived. As Saturn approached equinox, and the sun's light hit the rings edge-on, the spokes did reappear in the outer part of Saturn's B ring. But Cassini scientists are still testing their theories of what might be causing these odd features.
"The fact that we still have mysteries today goes to show how much we still have to learn about our solar system," said Suzanne Dodd, Voyager's project manager, based at JPL. "Today, the Voyager spacecraft continue as pioneers traveling toward the edge of our solar system. We can't wait for the Voyager spacecraft to enter interstellar space – true outer space – and make more unexpected discoveries."
Voyager 1, which was launched on Sept. 5, 1977, is currently about 17 billion kilometers (11 billion miles) away from the sun. It is the most distant spacecraft. Voyager 2, which was launched on Aug. 20, 1977, is currently about 14 billion kilometers (9 billion miles) away from the sun.
The Voyagers were built by JPL, which continues to operate both spacecraft. Caltech manages JPL for NASA. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages Cassini for NASA. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL.
For more information visit http://www.nasa.gov/mission_pages/voyager/voyager20101111.html
Stone drew a crude sketch of this scalloped, multi-stranded ring, known as the F ring, in his notebook, but with no explanation next to it. The innumerable particles comprising the broad rings are in near-circular orbits about Saturn. So, it was a surprise to find that the F ring, discovered just a year before by NASA's Pioneer 11 spacecraft, had clumps and wayward kinks. What could have created such a pattern?
"It was clear Voyager was showing us something different at Saturn," said Stone, now based at the California Institute of Technology in Pasadena. "Over and over, the spacecraft revealed so many unexpected things that it often took days, months and even years to figure them out."
The F ring curiosity was only one of many strange phenomena discovered in the Voyager close encounters with Saturn, which occurred on Nov. 12, 1980, for Voyager 1, and Aug. 25, 1981, for Voyager 2. The Voyager encounters were responsible for finding six small moons and revealing the half-young, half-old terrain of Enceladus that had to point to some kind of geological activity.
Images from the two encounters also exposed individual storms roiling the planet's atmosphere, which did not show up at all in data from Earth-based telescopes. Scientists used Voyager data to resolve a debate about whether Titan had a thick or thin atmosphere, finding that Titan was shrouded in a thick haze of hydrocarbons in a nitrogen-rich atmosphere. The finding led scientists to predict there could be seas of liquid methane and ethane on Titan's surface.
"When I look back, I realize how little we actually knew about the solar system before Voyager," Stone added. "We discovered things we didn't know were there to be discovered, time after time."
In fact, the Voyager encounters sparked so many new questions that another spacecraft, NASA's Cassini, was sent to probe those mysteries. While Voyager 1 got to within about 126,000 kilometers (78,300 miles) above Saturn's cloud tops, and Voyager 2 approached as close as about 100,800 kilometers (62,600 miles), Cassini has dipped to this altitude and somewhat lower in its orbits around Saturn since 2004.
Because of Cassini's extended journey around Saturn, scientists have found explanations for many of the mysteries first seen by Voyager. Cassini has uncovered a mechanism to explain the new terrain on Enceladus – tiger stripe fissures with jets of water vapor and organic particles. It revealed that Titan indeed does have stable lakes of liquid hydrocarbons on its surface and showed just how similar to Earth that moon really is. Data from Cassini have also resolved how two small moons discovered by Voyager – Prometheus and Pandora – tug on the F ring to create its kinked shape and wakes that form snowballs.
"Cassini is indebted to Voyager for its many fascinating discoveries and for paving the way for Cassini," said Linda Spilker, Cassini project scientist at JPL, who started her career working on Voyager from 1977 to 1989. "On Cassini, we still compare our data to Voyager's and proudly build on Voyager's heritage."
But Voyager left a few mysteries that Cassini has not yet solved. For instance, scientists first spotted a hexagonal weather pattern when they stitched together Voyager images of Saturn's north pole. Cassini has obtained higher-resolution pictures of the hexagon – which tells scientists it's a remarkably stable wave in one of the jet streams that remains 30 years later – but scientists are still not sure what forces maintain the hexagon.
Even more perplexing are the somewhat wedge-shaped, transient clouds of tiny particles that Voyager discovered orbiting in Saturn's B ring. Scientists dubbed them "spokes" because they looked like bicycle spokes. Cassini scientists have been searching for them since the spacecraft first arrived. As Saturn approached equinox, and the sun's light hit the rings edge-on, the spokes did reappear in the outer part of Saturn's B ring. But Cassini scientists are still testing their theories of what might be causing these odd features.
"The fact that we still have mysteries today goes to show how much we still have to learn about our solar system," said Suzanne Dodd, Voyager's project manager, based at JPL. "Today, the Voyager spacecraft continue as pioneers traveling toward the edge of our solar system. We can't wait for the Voyager spacecraft to enter interstellar space – true outer space – and make more unexpected discoveries."
Voyager 1, which was launched on Sept. 5, 1977, is currently about 17 billion kilometers (11 billion miles) away from the sun. It is the most distant spacecraft. Voyager 2, which was launched on Aug. 20, 1977, is currently about 14 billion kilometers (9 billion miles) away from the sun.
The Voyagers were built by JPL, which continues to operate both spacecraft. Caltech manages JPL for NASA. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages Cassini for NASA. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL.
For more information visit http://www.nasa.gov/mission_pages/voyager/voyager20101111.html
Wednesday, November 10, 2010
Cassini's CIRS Reveals Saturn Is on a Cosmic Dimmer Switch
Like a cosmic light bulb on a dimmer switch, Saturn emitted gradually less energy each year from 2005 to 2009, according to observations by NASA’s Cassini spacecraft. But unlike an ordinary bulb, Saturn's southern hemisphere consistently emitted more energy than its northern one. On top of that, energy levels changed with the seasons and differed from the last time a spacecraft visited in the early 1980s. These never-before-seen trends came from an analysis of comprehensive data from the Composite Infrared Spectrometer (CIRS), an instrument built by NASA's Goddard Space Flight Center in Greenbelt, Md., as well as a comparison with earlier data from NASA's Voyager spacecraft. When combined with information about the energy coming to Saturn from the sun, the results could help scientists understand the nature of Saturn's internal heat source.
The findings were reported November 9 in the Journal of Geophysical Research-Planets by Liming Li of Cornell University in Ithaca, N.Y. (now at the University of Houston), and colleagues from several institutions, including Goddard and NASA's Jet Propulsion Laboratory in Pasadena Calif., which manages the Cassini mission. "The Cassini CIRS data are very valuable because they give us a nearly complete picture of Saturn," says Li. "This is the only single data set that provides so much information about this planet, and it's the first time that anybody has been able to study the power emitted by one of the giant planets in such detail."
The planets in our solar system lose energy in the form of heat radiation in wavelengths that are invisible to the human eye. The CIRS instrument picks up wavelengths in the thermal infrared region, which is beyond red light, where the wavelengths correspond to heat emission.
"In planetary science, we tend to think of planets as losing power evenly in all directions and at a steady rate," says Li. "Now we know Saturn is not doing that." (Power is the amount of energy emitted per unit of time.)
Instead, Saturn's flow of outgoing energy was lopsided, with its southern hemisphere giving off about one-sixth more energy than the northern one, Li explains. This effect matched Saturn's seasons: during those five Earth years, it was summer in the southern hemisphere and winter in the northern one. (A season on Saturn lasts about seven Earth years.) Like Earth, Saturn has these seasons because the planet is tilted on its axis, so one hemisphere receives more energy from the sun and experiences summer while the other receives less energy and is shrouded in winter. Saturn’s equinox, when the sun was directly over the equator, occurred in August 2009.
In the study, Saturn's seasons looked Earth-like in another way: in each hemisphere, its effective temperature, which characterizes its thermal emission to space, started to warm up or cool down as a change of season approached. Because Saturn's weather is variable and the atmosphere tends to retain heat (called heat inertia), the temperature changes in complicated ways throughout the atmosphere. "The effective temperature provides us a simple way to track the response of Saturn's atmosphere, as a system, to the seasonal changes," says Li. Cassini's observations in the northern hemisphere revealed that the effective temperature gradually dropped from 2005 to 2008 and then started to warm up again by 2009. In Saturn's southern hemisphere, the effective temperature cooled from 2005 to 2009, as the equinox started to approach.
The emitted energy for each hemisphere rose and fell along with the effective temperature. Even so, during this five-year period, the planet as a whole seemed to be slowly cooling down and emitting less energy.
To find out if similar changes were happening one Saturn year ago, the researchers looked at data collected by Voyager in 1980 and 1981. Like Cassini CIRS, Voyager recorded fluctuations in the energy emitted by the planet and in the effective temperature. But Voyager did not see the imbalance between the southern and northern hemispheres; instead, the two regions were much more consistent with each other.
Why wouldn't Voyager have seen the same summer-versus-winter difference between the two hemispheres? The amount of energy coming from the sun (called solar radiance), which drives weather and atmospheric temperatures, could have fluctuated from one Saturn year to the next. The patterns in Saturn's cloud cover and haze could have, too.
"It's reasonable to think that the changes in Saturn's emitted power are related to cloud cover," says Amy Simon-Miller, who heads the Planetary Systems Laboratory at Goddard and is a co-author on the paper. "As the amount of cloud cover changes, the amount of radiation escaping into space also changes. This might vary during a single season and from one Saturn year to another. But to fully understand what is happening on Saturn, we will need the other half of the picture: the amount of power being absorbed by the planet."
Li is finishing an analysis of the solar energy that came to Saturn, based on data sets collected by two other Cassini instruments, the imaging science subsystem and the visual and infrared mapping spectrometer. He agrees that this information is crucial because Saturn, like its fellow giant planets Jupiter and Neptune, is thought to have its own source of internal energy. (The fourth giant planet, Uranus, does not seem to have an internal source.) By studying the changes in Saturn's outgoing energy along with the changes in incoming solar energy, scientists can learn about the nature of the planet's internal energy source and whether it, too, changes over time.
"The differences between Saturn's northern and southern hemisphere and that fact that Voyager did not see the same asymmetry raise a very important question: does Saturn's internal heat vary with time?" says Li. "The answer will significantly deepen our understanding of the weather, internal structure and evolution of Saturn and the other giant planets."
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA Goddard, where the instrument was built.
For more information visit http://www.nasa.gov/mission_pages/cassini/whycassini/dimmer-switch.html
The findings were reported November 9 in the Journal of Geophysical Research-Planets by Liming Li of Cornell University in Ithaca, N.Y. (now at the University of Houston), and colleagues from several institutions, including Goddard and NASA's Jet Propulsion Laboratory in Pasadena Calif., which manages the Cassini mission. "The Cassini CIRS data are very valuable because they give us a nearly complete picture of Saturn," says Li. "This is the only single data set that provides so much information about this planet, and it's the first time that anybody has been able to study the power emitted by one of the giant planets in such detail."
The planets in our solar system lose energy in the form of heat radiation in wavelengths that are invisible to the human eye. The CIRS instrument picks up wavelengths in the thermal infrared region, which is beyond red light, where the wavelengths correspond to heat emission.
"In planetary science, we tend to think of planets as losing power evenly in all directions and at a steady rate," says Li. "Now we know Saturn is not doing that." (Power is the amount of energy emitted per unit of time.)
Instead, Saturn's flow of outgoing energy was lopsided, with its southern hemisphere giving off about one-sixth more energy than the northern one, Li explains. This effect matched Saturn's seasons: during those five Earth years, it was summer in the southern hemisphere and winter in the northern one. (A season on Saturn lasts about seven Earth years.) Like Earth, Saturn has these seasons because the planet is tilted on its axis, so one hemisphere receives more energy from the sun and experiences summer while the other receives less energy and is shrouded in winter. Saturn’s equinox, when the sun was directly over the equator, occurred in August 2009.
In the study, Saturn's seasons looked Earth-like in another way: in each hemisphere, its effective temperature, which characterizes its thermal emission to space, started to warm up or cool down as a change of season approached. Because Saturn's weather is variable and the atmosphere tends to retain heat (called heat inertia), the temperature changes in complicated ways throughout the atmosphere. "The effective temperature provides us a simple way to track the response of Saturn's atmosphere, as a system, to the seasonal changes," says Li. Cassini's observations in the northern hemisphere revealed that the effective temperature gradually dropped from 2005 to 2008 and then started to warm up again by 2009. In Saturn's southern hemisphere, the effective temperature cooled from 2005 to 2009, as the equinox started to approach.
The emitted energy for each hemisphere rose and fell along with the effective temperature. Even so, during this five-year period, the planet as a whole seemed to be slowly cooling down and emitting less energy.
To find out if similar changes were happening one Saturn year ago, the researchers looked at data collected by Voyager in 1980 and 1981. Like Cassini CIRS, Voyager recorded fluctuations in the energy emitted by the planet and in the effective temperature. But Voyager did not see the imbalance between the southern and northern hemispheres; instead, the two regions were much more consistent with each other.
Why wouldn't Voyager have seen the same summer-versus-winter difference between the two hemispheres? The amount of energy coming from the sun (called solar radiance), which drives weather and atmospheric temperatures, could have fluctuated from one Saturn year to the next. The patterns in Saturn's cloud cover and haze could have, too.
"It's reasonable to think that the changes in Saturn's emitted power are related to cloud cover," says Amy Simon-Miller, who heads the Planetary Systems Laboratory at Goddard and is a co-author on the paper. "As the amount of cloud cover changes, the amount of radiation escaping into space also changes. This might vary during a single season and from one Saturn year to another. But to fully understand what is happening on Saturn, we will need the other half of the picture: the amount of power being absorbed by the planet."
Li is finishing an analysis of the solar energy that came to Saturn, based on data sets collected by two other Cassini instruments, the imaging science subsystem and the visual and infrared mapping spectrometer. He agrees that this information is crucial because Saturn, like its fellow giant planets Jupiter and Neptune, is thought to have its own source of internal energy. (The fourth giant planet, Uranus, does not seem to have an internal source.) By studying the changes in Saturn's outgoing energy along with the changes in incoming solar energy, scientists can learn about the nature of the planet's internal energy source and whether it, too, changes over time.
"The differences between Saturn's northern and southern hemisphere and that fact that Voyager did not see the same asymmetry raise a very important question: does Saturn's internal heat vary with time?" says Li. "The answer will significantly deepen our understanding of the weather, internal structure and evolution of Saturn and the other giant planets."
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA Goddard, where the instrument was built.
For more information visit http://www.nasa.gov/mission_pages/cassini/whycassini/dimmer-switch.html
Tuesday, November 9, 2010
NASA's Fermi Telescope Finds Giant Structure in our Galaxy
NASA's Fermi Gamma-ray Space Telescope has unveiled a previously unseen structure centered in the Milky Way. The feature spans 50,000 light-years and may be the remnant of an eruption from a supersized black hole at the center of our galaxy.
"What we see are two gamma-ray-emitting bubbles that extend 25,000 light-years north and south of the galactic center," said Doug Finkbeiner, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., who first recognized the feature. "We don't fully understand their nature or origin."
The structure spans more than half of the visible sky, from the constellation Virgo to the constellation Grus, and it may be millions of years old. A paper about the findings has been accepted for publication in The Astrophysical Journal.
Finkbeiner and his team discovered the bubbles by processing publicly available data from Fermi's Large Area Telescope (LAT). The LAT is the most sensitive and highest-resolution gamma-ray detector ever launched. Gamma rays are the highest-energy form of light.
"What we see are two gamma-ray-emitting bubbles that extend 25,000 light-years north and south of the galactic center," said Doug Finkbeiner, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., who first recognized the feature. "We don't fully understand their nature or origin."
The structure spans more than half of the visible sky, from the constellation Virgo to the constellation Grus, and it may be millions of years old. A paper about the findings has been accepted for publication in The Astrophysical Journal.
Finkbeiner and his team discovered the bubbles by processing publicly available data from Fermi's Large Area Telescope (LAT). The LAT is the most sensitive and highest-resolution gamma-ray detector ever launched. Gamma rays are the highest-energy form of light.
Other astronomers studying gamma rays hadn't detected the bubbles partly because of a fog of gamma rays that appears throughout the sky. The fog happens when particles moving near the speed of light interact with light and interstellar gas in the Milky Way. The LAT team constantly refines models to uncover new gamma-ray sources obscured by this so-called diffuse emission. By using various estimates of the fog, Finkbeiner and his colleagues were able to isolate it from the LAT data and unveil the giant bubbles.
Scientists now are conducting more analyses to better understand how the never-before-seen structure was formed. The bubble emissions are much more energetic than the gamma-ray fog seen elsewhere in the Milky Way. The bubbles also appear to have well-defined edges. The structure's shape and emissions suggest it was formed as a result of a large and relatively rapid energy release - the source of which remains a mystery.
One possibility includes a particle jet from the supermassive black hole at the galactic center. In many other galaxies, astronomers see fast particle jets powered by matter falling toward a central black hole. While there is no evidence the Milky Way's black hole has such a jet today, it may have in the past. The bubbles also may have formed as a result of gas outflows from a burst of star formation, perhaps the one that produced many massive star clusters in the Milky Way's center several million years ago.
"In other galaxies, we see that starbursts can drive enormous gas outflows," said David Spergel, a scientist at Princeton University in New Jersey. "Whatever the energy source behind these huge bubbles may be, it is connected to many deep questions in astrophysics."
Hints of the bubbles appear in earlier spacecraft data. X-ray observations from the German-led Roentgen Satellite suggested subtle evidence for bubble edges close to the galactic center, or in the same orientation as the Milky Way. NASA's Wilkinson Microwave Anisotropy Probe detected an excess of radio signals at the position of the gamma-ray bubbles.
The Fermi LAT team also revealed Tuesday the instrument's best picture of the gamma-ray sky, the result of two years of data collection.
"Fermi scans the entire sky every three hours, and as the mission continues and our exposure deepens, we see the extreme universe in progressively greater detail," said Julie McEnery, Fermi project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.
NASA's Fermi is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.
"Since its launch in June 2008, Fermi repeatedly has proven itself to be a frontier facility, giving us new insights ranging from the nature of space-time to the first observations of a gamma-ray nova," said Jon Morse, Astrophysics Division director at NASA Headquarters in Washington. “These latest discoveries continue to demonstrate Fermi's outstanding performance.”
For more information visit http://www.nasa.gov/mission_pages/GLAST/news/new-structure.html
Labels: NASA News
Monday, November 8, 2010
Sunspot 1121 Unleashes X-ray Flare
Active sunspot 1121 has unleashed one of the brightest x-ray solar flares in years, an M5.4-class eruption at 15:36 UT on Nov. 6th.
Radiation from the flare created a wave of ionization in Earth's upper atmosphere that altered the propagation of low-frequency radio waves. There was, however, no bright CME (plasma cloud) hurled in our direction, so the event is unlikely to produce auroras in the nights ahead.
This is the third M-flare in as many days from this increasingly active sunspot. So far none of the eruptions has been squarely Earth-directed, but this could change in the days ahead as the sun's rotation turns the active region toward our planet.
For more information visit http://www.nasa.gov/topics/solarsystem/sunearthsystem/main/News110610-Mflare.html
Radiation from the flare created a wave of ionization in Earth's upper atmosphere that altered the propagation of low-frequency radio waves. There was, however, no bright CME (plasma cloud) hurled in our direction, so the event is unlikely to produce auroras in the nights ahead.
This is the third M-flare in as many days from this increasingly active sunspot. So far none of the eruptions has been squarely Earth-directed, but this could change in the days ahead as the sun's rotation turns the active region toward our planet.
For more information visit http://www.nasa.gov/topics/solarsystem/sunearthsystem/main/News110610-Mflare.html
Sunday, November 7, 2010
NASA Extends TIMED Mission for Fourth Time
Nine years after beginning its unprecedented look at the gateway between Earth's environment and space, not to mention collecting more data on the upper atmosphere than any other satellite, NASA’s Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission has been extended again.
Before the launch of TIMED, the mesosphere and lower thermosphere/ionosphere -- which help protect us from harmful solar radiation -- had been one of the least explored and understood regions of our environment.
"The middle part of the atmosphere was the part we kind of ignored," says John Sigwarth, the deputy project scientist for TIMED at NASA's Goddard Space Flight Center in Greenbelt, MD. "It's too high for balloons and too low for spacecraft. So the understanding of this middle atmosphere and its impact on the upper atmosphere has been tremendously increased due to TIMED."
The mission will now continue to study the influences of the sun and humans on our upper atmosphere. TIMED began its extended mission on Oct. 1, 2010, and will collect data through 2014. This is its fourth extension since the original 2-year mission began in January 2002. TIMED will focus this time on a problem that has long puzzled scientists: differentiating between human-induced and naturally occurring changes in this atmospheric region. This extension also allows TIMED to continue collecting data for longer than a full 11-year solar cycle.
"The sun is a variable star with an 11 year cycle," says Sigwarth. "So, if things change in the mesosphere, you don't know if it's because the sun changed or because human activity has caused the change. By getting back to the same point in the cycle, we can compare what it was like then, and what it's like now, and see if there's a long term trend of changes that's not solar related."
The key instrument performing this work is known as SABER (or Sounding of the Atmosphere using Broadband Emission Radiometry), built by Hampton University in Hampton, Va. SABER can remotely sense composition and temperature in the mesosphere.
In addition to checking for effects from humans, TIMED scientists would like to understand how cooling temperatures in the middle atmosphere are causing the thermosphere to become less dense and its composition to change. With fewer particles in the thermosphere, there’s less drag on satellites in space, which affects how long spacecraft and space debris stay in orbit – information that must be integrated into calculations for orbit models.
Composition changes in the thermosphere can also alter ionospheric structures that affect radio wave propagation and communications. To help with this is an instrument called SEE (or the Solar EUV Experiment) built at the University of Colo., which looks at the sun's x-rays and extreme ultraviolet rays to see how they impact our atmosphere.
TIMED will also collaborate with NASA’s newest eye on the Sun, the Solar Dynamics Observatory, which provides continuing solar radiation measurements and new views of how solar activity is created.
NASA's Goddard Space Flight Center in Greenbelt, Md. manages the TIMED mission for the agency's Science Mission Directorate at NASA Headquarters in Washington. The spacecraft was built by the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.
For more information visit http://www.nasa.gov/topics/solarsystem/sunearthsystem/main/timed-extended.html
Before the launch of TIMED, the mesosphere and lower thermosphere/ionosphere -- which help protect us from harmful solar radiation -- had been one of the least explored and understood regions of our environment.
"The middle part of the atmosphere was the part we kind of ignored," says John Sigwarth, the deputy project scientist for TIMED at NASA's Goddard Space Flight Center in Greenbelt, MD. "It's too high for balloons and too low for spacecraft. So the understanding of this middle atmosphere and its impact on the upper atmosphere has been tremendously increased due to TIMED."
The mission will now continue to study the influences of the sun and humans on our upper atmosphere. TIMED began its extended mission on Oct. 1, 2010, and will collect data through 2014. This is its fourth extension since the original 2-year mission began in January 2002. TIMED will focus this time on a problem that has long puzzled scientists: differentiating between human-induced and naturally occurring changes in this atmospheric region. This extension also allows TIMED to continue collecting data for longer than a full 11-year solar cycle.
"The sun is a variable star with an 11 year cycle," says Sigwarth. "So, if things change in the mesosphere, you don't know if it's because the sun changed or because human activity has caused the change. By getting back to the same point in the cycle, we can compare what it was like then, and what it's like now, and see if there's a long term trend of changes that's not solar related."
The key instrument performing this work is known as SABER (or Sounding of the Atmosphere using Broadband Emission Radiometry), built by Hampton University in Hampton, Va. SABER can remotely sense composition and temperature in the mesosphere.
In addition to checking for effects from humans, TIMED scientists would like to understand how cooling temperatures in the middle atmosphere are causing the thermosphere to become less dense and its composition to change. With fewer particles in the thermosphere, there’s less drag on satellites in space, which affects how long spacecraft and space debris stay in orbit – information that must be integrated into calculations for orbit models.
Composition changes in the thermosphere can also alter ionospheric structures that affect radio wave propagation and communications. To help with this is an instrument called SEE (or the Solar EUV Experiment) built at the University of Colo., which looks at the sun's x-rays and extreme ultraviolet rays to see how they impact our atmosphere.
TIMED will also collaborate with NASA’s newest eye on the Sun, the Solar Dynamics Observatory, which provides continuing solar radiation measurements and new views of how solar activity is created.
NASA's Goddard Space Flight Center in Greenbelt, Md. manages the TIMED mission for the agency's Science Mission Directorate at NASA Headquarters in Washington. The spacecraft was built by the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.
For more information visit http://www.nasa.gov/topics/solarsystem/sunearthsystem/main/timed-extended.html
Wednesday, November 3, 2010
Mars Rovers Mission Using Cloud Computing
The project team that built and operates the Mars rovers Spirit and Opportunity has become the first NASA space mission to use cloud computing for daily mission operations.
Cloud computing is a way to gain fast flexibility in computing ability by ordering capacity on demand -- as if from the clouds -- and paying only for what is used. NASA's Mars Exploration Rover Project moved to this strategy last week for the software and data that the rovers' flight team uses to develop daily plans for rover activities. NASA's Jet Propulsion Laboratory, Pasadena, Calif., which manages the project, gained confidence in cloud computing from experience with other uses of the technology, including public participation sites about Mars exploration.
"This is a change to thinking about computer capacity and data storage as a commodity like electricity, or even the money in your bank account," said JPL's John Callas, rover project manager. "You don't keep all your money in your wallet. Instead you go to a nearby ATM and get cash when you need it. Your money is safe, and the bank can hold as much or as little of the money as you want. Data is the same way: You don't need to have it on you all the time. It can be safely stored elsewhere and you can get it anytime via an Internet connection.
"When we need more computing capacity, we don't need to install more servers if we can rent more capacity from the cloud for just the time we need it. This way we don't waste electricity and air conditioning with servers idling waiting to be used, and we don't have to worry about hardware maintenance and operating system obsolescence."
Spirit and Opportunity landed on Mars in January 2004 for what were planned as three-month missions. Bonus, extended missions have continued for more than six years. Opportunity is currently active, requiring daily activity plans by a team of engineers at JPL, and scientists at many locations in North America and Europe. Spirit has been silent since March 2010 and is believed to be in a low-power hibernation mode for the Martian winter.
"The rover project is well suited for cloud computing," said Khawaja Shams, a JPL software engineer supporting the project. "It has a widespread user community acting collaboratively. Cloud enables us to deliver the data to each user from nearby locations for faster reaction time." Also, the unexpected longevity of the mission means the volume of data used has outgrown the systems originally planned for handling and sharing data, which makes the virtually limitless capacity of cloud computing attractive.
JPL collaborated with the cloud team of Amazon.com Inc., Seattle, to plan and implement the use of cloud computing in the Mars Exploration Rover Project's daily operations. JPL developed the rover project's activity-planning software, called Maestro.
"We have worked closely with multiple cloud vendors since 2007 to learn the best ways to gain the advantages of cloud computing," said Tomas Soderstrom, chief technology officer for the JPL Office of the Chief Information Officer. "To implement JPL CIO Jim Rinaldi's vision of renting instead of buying capacity, we pragmatically look past the hype about cloud computing to find the practical, cost-efficient real mission applications. The Mars Exploration Rover project's use of clouds is one example of this results-oriented partnership. More will follow."
In support of the federal Open Government Initiative, which increases public access to data collected by the federal government, JPL collaborated with the cloud team at Microsoft Corp., Redmond, Wash., to launch the "Be a Martian" website in November 2009. The site enables the public to participate as citizen scientists to improve Mars maps and take part in Mars research tasks.
For another early use of cloud computing, JPL worked with the cloud team at Google Inc., Mountain View, Calif. The Google cloud served a project in which JPL and computer science students at the University of California, San Diego, developed an educational application enabling fifth- and sixth-graders to tag labels onto images from Mars spacecraft.
In addition to establishing a private cloud and working with Amazon, Google and Microsoft, JPL has also collaborated with other vendors of public cloud computing. Soderstrom said, "We defined a 'cloud-oriented architecture' to use clouds as an extension of our own resources and to run the computing and storage where it is most appropriate for each application."
The extended missions of Spirit and Opportunity have provided a resource for testing innovations during an active space mission for possible use in future missions. New software uploads giving the rovers added autonomy have been one example, and cloud computing is another. JPL is currently building and testing NASA's next Mars rover, Curiosity, for launch in late 2011 in the Mars Science Laboratory mission. This rover will land on Mars in August 2012.
Shams said, "The experience we gain using cloud computing for planning Opportunity's activities may be valuable when Curiosity reaches Mars, too."
For more information visit http://www.nasa.gov/mission_pages/mer/news/mer20101102.html
Cloud computing is a way to gain fast flexibility in computing ability by ordering capacity on demand -- as if from the clouds -- and paying only for what is used. NASA's Mars Exploration Rover Project moved to this strategy last week for the software and data that the rovers' flight team uses to develop daily plans for rover activities. NASA's Jet Propulsion Laboratory, Pasadena, Calif., which manages the project, gained confidence in cloud computing from experience with other uses of the technology, including public participation sites about Mars exploration.
"This is a change to thinking about computer capacity and data storage as a commodity like electricity, or even the money in your bank account," said JPL's John Callas, rover project manager. "You don't keep all your money in your wallet. Instead you go to a nearby ATM and get cash when you need it. Your money is safe, and the bank can hold as much or as little of the money as you want. Data is the same way: You don't need to have it on you all the time. It can be safely stored elsewhere and you can get it anytime via an Internet connection.
"When we need more computing capacity, we don't need to install more servers if we can rent more capacity from the cloud for just the time we need it. This way we don't waste electricity and air conditioning with servers idling waiting to be used, and we don't have to worry about hardware maintenance and operating system obsolescence."
Spirit and Opportunity landed on Mars in January 2004 for what were planned as three-month missions. Bonus, extended missions have continued for more than six years. Opportunity is currently active, requiring daily activity plans by a team of engineers at JPL, and scientists at many locations in North America and Europe. Spirit has been silent since March 2010 and is believed to be in a low-power hibernation mode for the Martian winter.
"The rover project is well suited for cloud computing," said Khawaja Shams, a JPL software engineer supporting the project. "It has a widespread user community acting collaboratively. Cloud enables us to deliver the data to each user from nearby locations for faster reaction time." Also, the unexpected longevity of the mission means the volume of data used has outgrown the systems originally planned for handling and sharing data, which makes the virtually limitless capacity of cloud computing attractive.
JPL collaborated with the cloud team of Amazon.com Inc., Seattle, to plan and implement the use of cloud computing in the Mars Exploration Rover Project's daily operations. JPL developed the rover project's activity-planning software, called Maestro.
"We have worked closely with multiple cloud vendors since 2007 to learn the best ways to gain the advantages of cloud computing," said Tomas Soderstrom, chief technology officer for the JPL Office of the Chief Information Officer. "To implement JPL CIO Jim Rinaldi's vision of renting instead of buying capacity, we pragmatically look past the hype about cloud computing to find the practical, cost-efficient real mission applications. The Mars Exploration Rover project's use of clouds is one example of this results-oriented partnership. More will follow."
In support of the federal Open Government Initiative, which increases public access to data collected by the federal government, JPL collaborated with the cloud team at Microsoft Corp., Redmond, Wash., to launch the "Be a Martian" website in November 2009. The site enables the public to participate as citizen scientists to improve Mars maps and take part in Mars research tasks.
For another early use of cloud computing, JPL worked with the cloud team at Google Inc., Mountain View, Calif. The Google cloud served a project in which JPL and computer science students at the University of California, San Diego, developed an educational application enabling fifth- and sixth-graders to tag labels onto images from Mars spacecraft.
In addition to establishing a private cloud and working with Amazon, Google and Microsoft, JPL has also collaborated with other vendors of public cloud computing. Soderstrom said, "We defined a 'cloud-oriented architecture' to use clouds as an extension of our own resources and to run the computing and storage where it is most appropriate for each application."
The extended missions of Spirit and Opportunity have provided a resource for testing innovations during an active space mission for possible use in future missions. New software uploads giving the rovers added autonomy have been one example, and cloud computing is another. JPL is currently building and testing NASA's next Mars rover, Curiosity, for launch in late 2011 in the Mars Science Laboratory mission. This rover will land on Mars in August 2012.
Shams said, "The experience we gain using cloud computing for planning Opportunity's activities may be valuable when Curiosity reaches Mars, too."
For more information visit http://www.nasa.gov/mission_pages/mer/news/mer20101102.html
Tuesday, November 2, 2010
Using Planet Colors to Search for Alien Earths
Earth is invitingly blue. Mars is angry red. Venus is brilliant white. Astronomers have learned that a planet's "true colors" can reveal important details. For example, Mars is red because its soil contains rusty red stuff called iron oxide. And the famous tint of our planet, the "blue marble"? It's because the atmosphere scatters blue light rays more strongly than red ones. Therefore the atmosphere looks blue from above and below.
Planets around other stars probably exhibit a rainbow of colors every bit as diverse as those in our solar system. And astronomers would like to eventually harness color to learn more about exoplanets. Are they rocky or gaseous — or earthlike?
In a study recently accepted for publication in The Astrophysical Journal, a team led by NASA astronomer Lucy McFadden and UCLA graduate student Carolyn Crow describe a simple way to distinguish between the planets of our solar system based on color information. Earth, in particular, stands out clearly among the planets, like a blue jay in a flock of seagulls.
"The method we developed separates the planets out," Crow says. "It makes Earth look unique."
This suggests that someday, when we have the technology to gather light from individual exoplanets, astronomers could use color information to identify earthlike worlds. "Eventually, as telescopes get bigger, there will be the light-gathering power to look at the colors of planets around other stars," McFadden says. "Their colors will tell us which ones to study in more detail."
Earth the Exoplanet
The project began in 2008, when Crow teamed up with McFadden, her faculty mentor at the University of Maryland in College Park. McFadden currently heads university and post-doctoral programs at NASA's Goddard Space Flight Center in Greenbelt, Maryland.
New color information about Earth, the moon, and Mars became available, thanks to NASA's Deep Impact spacecraft. En route to a planned encounter this November with Comet 103P/Hartley 2, Deep Impact observed Earth. The idea was to determine what our home looks like to alien astronomers and eventually use that insight to figure out how to spot earthlike worlds around other stars.
As Deep Impact cruised through space, its High Resolution Instrument (HRI) measured the intensity of Earth's light. HRI is an 11.8-inch (30 cm) telescope that feeds light through seven different color filters mounted on a revolving wheel. Each filter samples the incoming light at a different portion of the visible-light spectrum, from ultraviolet and blue to red and near-infrared. On May 28, 2008, Deep Impact even caught a glimpse of the moon's light as it crossed in front of Earth. Later, in 2009, HRI scoped Mars.
McFadden wondered what combination of color information from the filters would best distinguish Earth from the other planets and moons of the solar system. She recruited Crow to work on the project. Eight other researchers from NASA, the University of Maryland, the University of Washington (Seattle), and the Johns Hopkins University Applied Physics Lab also joined the team.
The Magic Mix
The Deep Impact color data covered Earth, the moon, and Mars. The relative amounts of light passing through the filters vary for each planet or moon, providing a kind of color fingerprint. To this the team added existing color information about Mercury, Venus, Jupiter, Saturn, Uranus, Neptune, and Saturn's moon Titan.
A simple side-by-side comparison of color data on all the major planets was a confusing mess. The team finally found a combination of three different filters — one in the blue, one in the green, and one in the red — that highlights the differences between the planets.
On a special "color-color" diagram the team created, the planets cluster into groups based on similarities in the wavelengths of sunlight that their surfaces and atmospheres reflect. The gas giants Jupiter and Saturn huddle in one corner, Uranus and Neptune in a different one. The rocky inner planets Mars, Venus, and Mercury cluster off in their own corner of "color space."
But Earth is the true loner in color space. Its uniqueness traces to two factors. One is the scattering of blue light by the atmosphere. This is called Rayleigh scattering, after the English scientist who discovered it.
The other reason Earth stands out in color space is because it does not absorb a lot of infrared light. That's because our atmosphere is low in infrared-absorbing gases like methane and ammonia, compared to the gas giant planets Jupiter and Saturn.
"It is Earth's atmosphere that dominates the colors of Earth," Crow says. "It's the scattering of light in the ultraviolet and the absence of absorption in the infrared."
Colorful Future
Someday, the three-filter approach may provide a rough "first cut" look at exoplanet surfaces and atmospheres. "There are some things we can tell from the colors but there are some things that we can't quite tell without additional information," Crow says.
For example, if an exoplanet shows a similar color fingerprint to Earth's, it would not necessarily mean that the planet has the blue skies and vast oceans of our home. But it would tell us to look at that planet more closely.
And that would be an important first step toward making sense of the colorful complexity of the 490 (and counting) alien planets already discovered, and the scores more on the way.
For more information visit http://www.nasa.gov/topics/universe/features/planet-colors.html
Planets around other stars probably exhibit a rainbow of colors every bit as diverse as those in our solar system. And astronomers would like to eventually harness color to learn more about exoplanets. Are they rocky or gaseous — or earthlike?
In a study recently accepted for publication in The Astrophysical Journal, a team led by NASA astronomer Lucy McFadden and UCLA graduate student Carolyn Crow describe a simple way to distinguish between the planets of our solar system based on color information. Earth, in particular, stands out clearly among the planets, like a blue jay in a flock of seagulls.
"The method we developed separates the planets out," Crow says. "It makes Earth look unique."
This suggests that someday, when we have the technology to gather light from individual exoplanets, astronomers could use color information to identify earthlike worlds. "Eventually, as telescopes get bigger, there will be the light-gathering power to look at the colors of planets around other stars," McFadden says. "Their colors will tell us which ones to study in more detail."
Earth the Exoplanet
The project began in 2008, when Crow teamed up with McFadden, her faculty mentor at the University of Maryland in College Park. McFadden currently heads university and post-doctoral programs at NASA's Goddard Space Flight Center in Greenbelt, Maryland.
New color information about Earth, the moon, and Mars became available, thanks to NASA's Deep Impact spacecraft. En route to a planned encounter this November with Comet 103P/Hartley 2, Deep Impact observed Earth. The idea was to determine what our home looks like to alien astronomers and eventually use that insight to figure out how to spot earthlike worlds around other stars.
As Deep Impact cruised through space, its High Resolution Instrument (HRI) measured the intensity of Earth's light. HRI is an 11.8-inch (30 cm) telescope that feeds light through seven different color filters mounted on a revolving wheel. Each filter samples the incoming light at a different portion of the visible-light spectrum, from ultraviolet and blue to red and near-infrared. On May 28, 2008, Deep Impact even caught a glimpse of the moon's light as it crossed in front of Earth. Later, in 2009, HRI scoped Mars.
McFadden wondered what combination of color information from the filters would best distinguish Earth from the other planets and moons of the solar system. She recruited Crow to work on the project. Eight other researchers from NASA, the University of Maryland, the University of Washington (Seattle), and the Johns Hopkins University Applied Physics Lab also joined the team.
The Magic Mix
The Deep Impact color data covered Earth, the moon, and Mars. The relative amounts of light passing through the filters vary for each planet or moon, providing a kind of color fingerprint. To this the team added existing color information about Mercury, Venus, Jupiter, Saturn, Uranus, Neptune, and Saturn's moon Titan.
A simple side-by-side comparison of color data on all the major planets was a confusing mess. The team finally found a combination of three different filters — one in the blue, one in the green, and one in the red — that highlights the differences between the planets.
On a special "color-color" diagram the team created, the planets cluster into groups based on similarities in the wavelengths of sunlight that their surfaces and atmospheres reflect. The gas giants Jupiter and Saturn huddle in one corner, Uranus and Neptune in a different one. The rocky inner planets Mars, Venus, and Mercury cluster off in their own corner of "color space."
But Earth is the true loner in color space. Its uniqueness traces to two factors. One is the scattering of blue light by the atmosphere. This is called Rayleigh scattering, after the English scientist who discovered it.
The other reason Earth stands out in color space is because it does not absorb a lot of infrared light. That's because our atmosphere is low in infrared-absorbing gases like methane and ammonia, compared to the gas giant planets Jupiter and Saturn.
"It is Earth's atmosphere that dominates the colors of Earth," Crow says. "It's the scattering of light in the ultraviolet and the absence of absorption in the infrared."
Colorful Future
Someday, the three-filter approach may provide a rough "first cut" look at exoplanet surfaces and atmospheres. "There are some things we can tell from the colors but there are some things that we can't quite tell without additional information," Crow says.
For example, if an exoplanet shows a similar color fingerprint to Earth's, it would not necessarily mean that the planet has the blue skies and vast oceans of our home. But it would tell us to look at that planet more closely.
And that would be an important first step toward making sense of the colorful complexity of the 490 (and counting) alien planets already discovered, and the scores more on the way.
For more information visit http://www.nasa.gov/topics/universe/features/planet-colors.html
Monday, November 1, 2010
Cassini Sees Saturn Rings Oscillate Like Mini-Galaxy
Scientists believe they finally understand why one of the most dynamic regions in Saturn's rings has such an irregular and varying shape, thanks to images captured by NASA's Cassini spacecraft. And the answer, published online today in the Astronomical Journal, is this: The rings are behaving like a miniature version of our own Milky Way galaxy.
This new insight, garnered from images of Saturn's most massive ring, the B ring, may answer another long-standing question: What causes the bewildering variety of structures seen throughout the very densest regions of Saturn's rings?
Another finding from new images of the B ring's outer edge was the presence of at least two perturbed regions, including a long arc of narrow, shadow-casting peaks as high as 3.5 kilometers (2 miles) above the ring plane. The areas are likely populated with small moons that might have migrated across the outer part of the B ring in the past and got trapped in a zone affected by the moon Mimas' gravity. This process is commonly believed to have configured the present-day solar system.
"We have found what we hoped we'd find when we set out on this journey with Cassini nearly 13 years ago: visibility into the mechanisms that have sculpted not only Saturn's rings, but celestial disks of a far grander scale, from solar systems, like our own, all the way to the giant spiral galaxies," said Carolyn Porco, co-author on the new paper and Cassini imaging team lead, based at the Space Science Institute, Boulder, Colo.
Since NASA's Voyager spacecraft flew by Saturn in 1980 and 1981, scientists have known that the outer edge of the planet's B ring was shaped like a rotating, flattened football by the gravitational perturbations of Mimas. But it was clear, even in Voyager's findings, that the outer B ring's behavior was far more complex than anything Mimas alone might do.
Now, analysis of thousands of Cassini images of the B ring taken over a four-year period has revealed the source of most of the complexity: at least three additional, independently rotating wave patterns, or oscillations, that distort the B ring's edge. These oscillations, with one, two or three lobes, are not created by any moons. They have instead spontaneously arisen, in part because the ring is dense enough, and the B ring edge is sharp enough, for waves to grow on their own and then reflect at the edge.
"These oscillations exist for the same reason that guitar strings have natural modes of oscillation, which can be excited when plucked or otherwise disturbed," said Joseph Spitale, lead author on today's article and an imaging team associate at the Space Science Institute. "The ring, too, has its own natural oscillation frequencies, and that's what we're observing."
Astronomers believe such "self-excited" oscillations exist in other disk systems, like spiral disk galaxies and proto-planetary disks found around nearby stars, but they have not been able to directly confirm their existence. The new observations confirm the first large-scale wave oscillations of this type in a broad disk of material anywhere in nature.
Self-excited waves on small, 100-meter (300-foot) scales have been previously observed by Cassini instruments in a few dense ring regions and have been attributed to a process called "viscous overstability." In that process, the ring particles' small, random motions feed energy into a wave and cause it to grow. The new results confirm a Voyager-era predication that this same process can explain all the puzzling chaotic waveforms found in Saturn's densest rings, from tens of meters up to hundreds of kilometers wide.
"Normally viscosity, or resistance to flow, damps waves -- the way sound waves traveling through the air would die out," said Peter Goldreich, a planetary ring theorist at the California Institute of Technology in Pasadena. "But the new findings show that, in the densest parts of Saturn's rings, viscosity actually amplifies waves, explaining mysterious grooves first seen in images taken by the Voyager spacecraft."
The two perturbed B ring regions found orbiting within Mimas' zone of influence stretch along arcs up to 20,000 kilometers (12,000 miles) long. The longest one was first seen last year when the sun's low angle on the ring plane betrayed the existence of a series of tall structures through their long, spiky shadows. The small moons disturbing the material are probably hundreds of meters to possibly a kilometer or more in size.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.
For more information visit http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20101101.html
This new insight, garnered from images of Saturn's most massive ring, the B ring, may answer another long-standing question: What causes the bewildering variety of structures seen throughout the very densest regions of Saturn's rings?
Another finding from new images of the B ring's outer edge was the presence of at least two perturbed regions, including a long arc of narrow, shadow-casting peaks as high as 3.5 kilometers (2 miles) above the ring plane. The areas are likely populated with small moons that might have migrated across the outer part of the B ring in the past and got trapped in a zone affected by the moon Mimas' gravity. This process is commonly believed to have configured the present-day solar system.
"We have found what we hoped we'd find when we set out on this journey with Cassini nearly 13 years ago: visibility into the mechanisms that have sculpted not only Saturn's rings, but celestial disks of a far grander scale, from solar systems, like our own, all the way to the giant spiral galaxies," said Carolyn Porco, co-author on the new paper and Cassini imaging team lead, based at the Space Science Institute, Boulder, Colo.
Since NASA's Voyager spacecraft flew by Saturn in 1980 and 1981, scientists have known that the outer edge of the planet's B ring was shaped like a rotating, flattened football by the gravitational perturbations of Mimas. But it was clear, even in Voyager's findings, that the outer B ring's behavior was far more complex than anything Mimas alone might do.
Now, analysis of thousands of Cassini images of the B ring taken over a four-year period has revealed the source of most of the complexity: at least three additional, independently rotating wave patterns, or oscillations, that distort the B ring's edge. These oscillations, with one, two or three lobes, are not created by any moons. They have instead spontaneously arisen, in part because the ring is dense enough, and the B ring edge is sharp enough, for waves to grow on their own and then reflect at the edge."These oscillations exist for the same reason that guitar strings have natural modes of oscillation, which can be excited when plucked or otherwise disturbed," said Joseph Spitale, lead author on today's article and an imaging team associate at the Space Science Institute. "The ring, too, has its own natural oscillation frequencies, and that's what we're observing."
Astronomers believe such "self-excited" oscillations exist in other disk systems, like spiral disk galaxies and proto-planetary disks found around nearby stars, but they have not been able to directly confirm their existence. The new observations confirm the first large-scale wave oscillations of this type in a broad disk of material anywhere in nature.
Self-excited waves on small, 100-meter (300-foot) scales have been previously observed by Cassini instruments in a few dense ring regions and have been attributed to a process called "viscous overstability." In that process, the ring particles' small, random motions feed energy into a wave and cause it to grow. The new results confirm a Voyager-era predication that this same process can explain all the puzzling chaotic waveforms found in Saturn's densest rings, from tens of meters up to hundreds of kilometers wide.
"Normally viscosity, or resistance to flow, damps waves -- the way sound waves traveling through the air would die out," said Peter Goldreich, a planetary ring theorist at the California Institute of Technology in Pasadena. "But the new findings show that, in the densest parts of Saturn's rings, viscosity actually amplifies waves, explaining mysterious grooves first seen in images taken by the Voyager spacecraft."
The two perturbed B ring regions found orbiting within Mimas' zone of influence stretch along arcs up to 20,000 kilometers (12,000 miles) long. The longest one was first seen last year when the sun's low angle on the ring plane betrayed the existence of a series of tall structures through their long, spiky shadows. The small moons disturbing the material are probably hundreds of meters to possibly a kilometer or more in size.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.
For more information visit http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20101101.html
Sunday, October 31, 2010
NASA Survey Suggests Earth-Sized Planets Are Common
Nearly one in four stars similar to the sun may host planets as small as Earth, according to a new study funded by NASA and the University of California.
The study is the most extensive and sensitive planetary census of its kind. Astronomers used the W.M. Keck Observatory in Hawaii for five years to search 166 sun-like stars near our solar system for planets of various sizes, ranging from three to 1,000 times the mass of Earth. All of the planets in the study orbit close to their stars. The results show more small planets than large ones, indicating small planets are more prevalent in our Milky Way galaxy.
"We studied planets of many masses -- like counting boulders, rocks and pebbles in a canyon -- and found more rocks than boulders, and more pebbles than rocks. Our ground-based technology can't see the grains of sand, the Earth-size planets, but we can estimate their numbers," said Andrew Howard of the University of California, Berkeley, lead author of the new study. "Earth-size planets in our galaxy are like grains of sand sprinkled on a beach -- they are everywhere."
The study appears in the Oct. 29 issue of the journal Science.
The research provides a tantalizing clue that potentially habitable planets could also be common. These hypothesized Earth-size worlds would orbit farther away from their stars, where conditions could be favorable for life. NASA's Kepler spacecraft is also surveying sun-like stars for planets and is expected to find the first true Earth-like planets in the next few years.
Howard and his planet-hunting team, which includes principal investigator Geoff Marcy, also of the University of California, Berkeley, looked for planets within 80-light-years of Earth, using the radial velocity, or "wobble," technique.
They measured the numbers of planets falling into five groups, ranging from 1,000 times the mass of Earth, or about three times the mass of Jupiter, down to three times the mass of Earth. The search was confined to planets orbiting close to their stars -- within 0.25 astronomical units, or a quarter of the distance between our sun and Earth.
A distinct trend jumped out of the data: smaller planets outnumber larger ones. Only 1.6 percent of stars were found to host giant planets orbiting close in. That includes the three highest-mass planet groups in the study, or planets comparable to Saturn and Jupiter. About 6.5 percent of stars were found to have intermediate-mass planets, with 10 to 30 times the mass of Earth -- planets the size of Neptune and Uranus. And 11.8 percent had the so-called "super-Earths," weighing in at only three to 10 times the mass of Earth.
"During planet formation, small bodies similar to asteroids and comets stick together, eventually growing to Earth-size and beyond. Not all of the planets grow large enough to become giant planets like Saturn and Jupiter," Howard said. "It's natural for lots of these building blocks, the small planets, to be left over in this process."
The astronomers extrapolated from these survey data to estimate that 23 percent of sun-like stars in our galaxy host even smaller planets, the Earth-sized ones, orbiting in the hot zone close to a star. "This is the statistical fruit of years of planet-hunting work," said Marcy. "The data tell us that our galaxy, with its roughly 200 billion stars, has at least 46 billion Earth-size planets, and that's not counting Earth-size planets that orbit farther away from their stars in the habitable zone."
The findings challenge a key prediction of some theories of planet formation. Models predict a planet "desert" in the hot-zone region close to stars, or a drop in the numbers of planets with masses less than 30 times that of Earth. This desert was thought to arise because most planets form in the cool, outer region of solar systems, and only the giant planets were thought to migrate in significant numbers into the hot inner region. The new study finds a surplus of close-in, small planets where theories had predicted a scarcity.
"We are at the cusp of understanding the frequency of Earth-sized planets among planetary systems in the solar neighborhood," said Mario R. Perez, Keck program scientist at NASA Headquarters in Washington. "This work is part of a key NASA science program and will stimulate new theories to explain the significance and impact of these findings."
NASA's Exoplanet Science Institute at the California Institute of Technology, Pasadena, Calif., manages time allocation on the Keck telescope for NASA. NASA's Jet Propulsion Laboratory, also in Pasadena, manages NASA's Exoplanet Exploration program office.
For More information visit http://www.nasa.gov/topics/universe/features/exoplanet20101028.html
Thursday, October 28, 2010
NASA Trapped Mars Rover Finds Evidence of Subsurface Water
The ground where NASA's Mars Exploration Rover Spirit became stuck last year holds evidence that water, perhaps as snow melt, trickled into the subsurface fairly recently and on a continuing basis.
Stratified soil layers with different compositions close to the surface led the rover science team to propose that thin films of water may have entered the ground from frost or snow. The seepage could have happened during cyclical climate changes in periods when Mars tilted farther on its axis. The water may have moved down into the sand, carrying soluble minerals deeper than less soluble ones. Spin-axis tilt varies over timescales of hundreds of thousands of years.
The relatively insoluble minerals near the surface include what is thought to be hematite, silica and gypsum. Ferric sulfates, which are more soluble, appear to have been dissolved and carried down by water. None of these minerals are exposed at the surface, which is covered by wind-blown sand and dust.
"The lack of exposures at the surface indicates the preferential dissolution of ferric sulfates must be a relatively recent and ongoing process since wind has been systematically stripping soil and altering landscapes in the region Spirit has been examining," said Ray Arvidson of Washington University in St. Louis, deputy principal investigator for the twin rovers Spirit and Opportunity.
Analysis of these findings appears in a report in the Journal of Geophysical Research published by Arvidson and 36 co-authors about Spirit's operations from late 2007 until just before the rover stopped communicating in March.
The twin Mars rovers finished their three-month prime missions in April 2004, then kept exploring in bonus missions. One of Spirit's six wheels quit working in 2006.
In April 2009, Spirit's left wheels broke through a crust at a site called "Troy" and churned into soft sand. A second wheel stopped working seven months later. Spirit could not obtain a position slanting its solar panels toward the sun for the winter, as it had for previous winters. Engineers anticipated it would enter a low-power, silent hibernation mode, and the rover stopped communicating March 22. Spring begins next month at Spirit's site, and NASA is using the Deep Space Network and the Mars Odyssey orbiter to listen if the rover reawakens.
Researchers took advantage of Spirit's months at Troy last year to examine in great detail soil layers the wheels had exposed, and also neighboring surfaces. Spirit made 13 inches of progress in its last 10 backward drives before energy levels fell too low for further driving in February. Those drives exposed a new area of soil for possible examination if Spirit does awaken and its robotic arm is still usable.
"With insufficient solar energy during the winter, Spirit goes into a deep-sleep hibernation mode where all rover systems are turned off, including the radio and survival heaters," said John Callas, project manager for Spirit and Opportunity at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "All available solar array energy goes into charging the batteries and keeping the mission clock running."
The rover is expected to have experienced temperatures colder than it has ever before, and it may not survive. If Spirit does get back to work, the top priority is a multi-month study that can be done without driving the rover. The study would measure the rotation of Mars through the Doppler signature of the stationary rover's radio signal with enough precision to gain new information about the planet's core. The rover Opportunity has been making steady progress toward a large crater, Endeavour, which is now approximately 8 kilometers (5 miles) away.
Spirit, Opportunity, and other NASA Mars missions have found evidence of wet Martian environments billions of years ago that were possibly favorable for life. The Phoenix Mars Lander in 2008 and observations by orbiters since 2002 have identified buried layers of water ice at high and middle latitudes and frozen water in polar ice caps. These newest Spirit findings contribute to an accumulating set of clues that Mars may still have small amounts of liquid water at some periods during ongoing climate cycles.
JPL, a division of the California Institute of Technology in Pasadena, manages the rovers for the agency's Science Mission Directorate in Washington.
Stratified soil layers with different compositions close to the surface led the rover science team to propose that thin films of water may have entered the ground from frost or snow. The seepage could have happened during cyclical climate changes in periods when Mars tilted farther on its axis. The water may have moved down into the sand, carrying soluble minerals deeper than less soluble ones. Spin-axis tilt varies over timescales of hundreds of thousands of years.
The relatively insoluble minerals near the surface include what is thought to be hematite, silica and gypsum. Ferric sulfates, which are more soluble, appear to have been dissolved and carried down by water. None of these minerals are exposed at the surface, which is covered by wind-blown sand and dust.
"The lack of exposures at the surface indicates the preferential dissolution of ferric sulfates must be a relatively recent and ongoing process since wind has been systematically stripping soil and altering landscapes in the region Spirit has been examining," said Ray Arvidson of Washington University in St. Louis, deputy principal investigator for the twin rovers Spirit and Opportunity.
Analysis of these findings appears in a report in the Journal of Geophysical Research published by Arvidson and 36 co-authors about Spirit's operations from late 2007 until just before the rover stopped communicating in March.
The twin Mars rovers finished their three-month prime missions in April 2004, then kept exploring in bonus missions. One of Spirit's six wheels quit working in 2006.
In April 2009, Spirit's left wheels broke through a crust at a site called "Troy" and churned into soft sand. A second wheel stopped working seven months later. Spirit could not obtain a position slanting its solar panels toward the sun for the winter, as it had for previous winters. Engineers anticipated it would enter a low-power, silent hibernation mode, and the rover stopped communicating March 22. Spring begins next month at Spirit's site, and NASA is using the Deep Space Network and the Mars Odyssey orbiter to listen if the rover reawakens.
Researchers took advantage of Spirit's months at Troy last year to examine in great detail soil layers the wheels had exposed, and also neighboring surfaces. Spirit made 13 inches of progress in its last 10 backward drives before energy levels fell too low for further driving in February. Those drives exposed a new area of soil for possible examination if Spirit does awaken and its robotic arm is still usable.
"With insufficient solar energy during the winter, Spirit goes into a deep-sleep hibernation mode where all rover systems are turned off, including the radio and survival heaters," said John Callas, project manager for Spirit and Opportunity at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "All available solar array energy goes into charging the batteries and keeping the mission clock running."
The rover is expected to have experienced temperatures colder than it has ever before, and it may not survive. If Spirit does get back to work, the top priority is a multi-month study that can be done without driving the rover. The study would measure the rotation of Mars through the Doppler signature of the stationary rover's radio signal with enough precision to gain new information about the planet's core. The rover Opportunity has been making steady progress toward a large crater, Endeavour, which is now approximately 8 kilometers (5 miles) away.
Spirit, Opportunity, and other NASA Mars missions have found evidence of wet Martian environments billions of years ago that were possibly favorable for life. The Phoenix Mars Lander in 2008 and observations by orbiters since 2002 have identified buried layers of water ice at high and middle latitudes and frozen water in polar ice caps. These newest Spirit findings contribute to an accumulating set of clues that Mars may still have small amounts of liquid water at some periods during ongoing climate cycles.
JPL, a division of the California Institute of Technology in Pasadena, manages the rovers for the agency's Science Mission Directorate in Washington.
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