10:26 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
With a loud roar and mighty column of flame, NASA and ATK Aerospace Systems successfully completed a two-minute, full-scale test of the largest and most powerful solid rocket motor designed for flight. The motor is potentially transferable to future heavy-lift launch vehicle designs.
The stationary firing of the first-stage development solid rocket motor, dubbed DM-2, was conducted by ATK, a division of Alliant Techsystems of Brigham City, Utah. DM-2 is the most heavily instrumented solid rocket motor in NASA history, with a total of 53 test objectives measured through more than 760 instruments.
Prior to the static test, the solid rocket motor was cooled to 40 degrees Fahrenheit to verify the performance of new materials and assess motor performance at low temperatures during the full-duration test. Initial test data showed the motor performance met all expectations.
For more information visit http://www.nasa.gov/mission_pages/constellation/ares/10-202.html
useful links: Ferrini Boots, boy suits, Alligator boots
9:44 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
This detailed geologic map of Schrödinger basin, which formed when a huge object struck the moon, reveals a patchwork of lunar material, including the peak ring (inner brown ring), recent volcanic activity (red), cratering (yellow) and plains material (dark green and kelly green). Credit: NASA/Scott Mest - Larger image A new geologic map of the moon's Schrödinger basin paints an instant, camouflage-colored portrait of what a mash-up the moon's surface is after eons of violent events. The geologic record at Schrödinger is still relatively fresh because the basin is only about 3.8 billion years old; this makes it the moon's second-youngest large basin (it's roughly 320 kilometers, or 200 miles, in diameter).
Schrödinger is located near the moon's south pole, a region where pockets of permanent ice are thought to exist. The map will help researchers understand lunar geologic history and identify suitable landing sites for future exploration. Scott Mest, a research scientist with the Planetary Science Institute working at NASA's Goddard Space Flight Center in Greenbelt, Md., and his colleagues created this geologic map -- the most detailed one to date -- by combining topographic data from the Lunar Orbiter Laser Altimeter, a Goddard instrument aboard the 2009 Lunar Reconnaissance Orbiter, with images and spectral data from the earlier Clementine and Lunar Prospector missions.
Schrödinger is an example of an intriguing type of basin called a peak-ring. Like the basin rim (brown outer ring), the smaller and more fragmented peak ring (brown inner ring) is a mountainous region of crust that rose up after a huge object, probably measuring 35-40 kilometers, or about 21-25 miles, smacked into the moon here. These areas of raised crust are the oldest rocks in the basin and just about the only material that wasn't melted by the heat from the object's impact. The melted material was spewed in all directions and formed the plains. Patches of plains material can have slightly different textures and albedo (indicated by dark green and kelly green), probably because they cooled at different times. Fractures (black lines) formed in the basin floor as the material cooled.
Schrödinger Basin is one of the few areas near the moon's south pole with evidence of recent volcanic activity. This includes lava flows from volcanic activity on the surface (beige areas) as well as explosive eruptions from a vent inside the red area; this vent has brought up dark material that mantles the plains (red area, which is newer than the beige regions). Older volcanic material is spread over a wider range (gray and lime green). More recent cratering by smaller objects has scattered material (yellow areas) near the top of the basin. Next to that (very light green beside yellow) is a region with a knobby texture that suggests loose material that could have come from cratering outside the basin or from a landslide on the basin's rim.
For more information visit http://www.nasa.gov/mission_pages/LRO/news/camo-moon.html
useful links: Ferrini Boots, boy suits, Alligator boots
8:57 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
NASA's STEREO (Ahead) spacecraft watched as an eruptive prominence rose up and arched out in a horseshoe shape far above the Sun's surface (Aug. 25, 2010). The image and movie show the action in an extreme UV wavelength as an eruptive prominence churns, then rises up, arches out, and finally breaks apart and dissipates above the solar surface. Prominences are clouds of relatively cool gases suspended in the Sun's hot corona by magnetic fields that sometimes break loose to create these dramatic eruptions. The video clip covers about 30 hours of activity. This is one of the brightest and most substantial CMEs and largest eruptive prominences we have seen in several years.
For more information visit http://www.nasa.gov/topics/solarsystem/sunearthsystem/main/News082710-prom.html
9:06 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
NASA's Kepler spacecraft has discovered the first confirmed planetary system with more than one planet crossing in front of, or transiting, the same star.
The transit signatures of two distinct planets were seen in the data for the sun-like star designated Kepler-9. The planets were named Kepler-9b and 9c. The discovery incorporates seven months of observations of more than 156,000 stars as part of an ongoing search for Earth-sized planets outside our solar system. The findings will be published in Thursday's issue of the journal Science.
Kepler's ultra-precise camera measures tiny decreases in the stars' brightness that occur when a planet transits them. The size of the planet can be derived from these temporary dips.
The distance of the planet from the star can be calculated by measuring the time between successive dips as the planet orbits the star. Small variations in the regularity of these dips can be used to determine the masses of planets and detect other non-transiting planets in the system.
In June, mission scientists submitted findings for peer review that identified more than 700 planet candidates in the first 43 days of Kepler data. The data included five additional candidate systems that appear to exhibit more than one transiting planet. The Kepler team recently identified a sixth target exhibiting multiple transits and accumulated enough follow-up data to confirm this multi-planet system.
"Kepler's high quality data and round-the-clock coverage of transiting objects enable a whole host of unique measurements to be made of the parent stars and their planetary systems," said Doug Hudgins, the Kepler program scientist at NASA Headquarters in Washington.
Scientists refined the estimates of the masses of the planets using observations from the W.M. Keck Observatory in Hawaii. The observations show Kepler-9b is the larger of the two planets, and both have masses similar to but less than Saturn. Kepler-9b lies closest to the star with an orbit of about 19 days, while Kepler-9c has an orbit of about 38 days. By observing several transits by each planet over the seven months of data, the time between successive transits could be analyzed.
"This discovery is the first clear detection of significant changes in the intervals from one planetary transit to the next, what we call transit timing variations," said Matthew Holman, a Kepler mission scientist from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "This is evidence of the gravitational interaction between the two planets as seen by the Kepler spacecraft."
In addition to the two confirmed giant planets, Kepler scientists also have identified what appears to be a third, much smaller transit signature in the observations of Kepler-9. That signature is consistent with the transits of a super-Earth-sized planet about 1.5 times the radius of Earth in a scorching, near-sun 1.6 day-orbit. Additional observations are required to determine whether this signal is indeed a planet or an astronomical phenomenon that mimics the appearance of a transit.
NASA's Ames Research Center in Moffett Field, Calif., manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development.
Ball Aerospace and Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes the Kepler science data.
For more information visit http://www.nasa.gov/mission_pages/kepler/news/two_planet_orbit.html
useful links: Ferrini Boots, boy suits, Alligator boots
9:45 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
A relatively new type of El Niño, which has its warmest waters in the central-equatorial Pacific Ocean, rather than in the eastern-equatorial Pacific, is becoming more common and progressively stronger, according to a new study by NASA and NOAA. The research may improve our understanding of the relationship between El Niños and climate change, and has potentially significant implications for long-term weather forecasting.
Lead author Tong Lee of NASA's Jet Propulsion Laboratory, Pasadena, Calif., and Michael McPhaden of NOAA's Pacific Marine Environmental Laboratory, Seattle, measured changes in El Niño intensity since 1982. They analyzed NOAA satellite observations of sea surface temperature, checked against and blended with directly-measured ocean temperature data. The strength of each El Niño was gauged by how much its sea surface temperatures deviated from the average. They found the intensity of El Niños in the central Pacific has nearly doubled, with the most intense event occurring in 2009-10.
The scientists say the stronger El Niños help explain a steady rise in central Pacific sea surface temperatures observed over the past few decades in previous studies--a trend attributed by some to the effects of global warming. While Lee and McPhaden observed a rise in sea surface temperatures during El Niño years, no significant temperature increases were seen in years when ocean conditions were neutral, or when El Niño's cool water counterpart, La Niña, was present.
"Our study concludes the long-term warming trend seen in the central Pacific is primarily due to more intense El Niños, rather than a general rise of background temperatures," said Lee.
"These results suggest climate change may already be affecting El Niño by shifting the center of action from the eastern to the central Pacific," said McPhaden. "El Niño's impact on global weather patterns is different if ocean warming occurs primarily in the central Pacific, instead of the eastern Pacific.
"If the trend we observe continues," McPhaden added, "it could throw a monkey wrench into long-range weather forecasting, which is largely based on our understanding of El Niños from the latter half of the 20th century."
El Niño, Spanish for "the little boy," is the oceanic component of a climate pattern called the El Niño-Southern Oscillation, which appears in the tropical Pacific Ocean on average every three to five years. The most dominant year-to-year fluctuating pattern in Earth's climate system, El Niños have a powerful impact on the ocean and atmosphere, as well as important socioeconomic consequences. They can influence global weather patterns and the occurrence and frequency of hurricanes, droughts and floods; and can even raise or lower global temperatures by as much as 0.2 degrees Celsius (0.4 degrees Fahrenheit).
During a "classic" El Niño episode, the normally strong easterly trade winds in the tropical eastern Pacific weaken. That weakening suppresses the normal upward movement of cold subsurface waters and allows warm surface water from the central Pacific to shift toward the Americas. In these situations, unusually warm surface water occupies much of the tropical Pacific, with the maximum ocean warming remaining in the eastern-equatorial Pacific.
Since the early 1990s, however, scientists have noted a new type of El Niño that has been occurring with greater frequency. Known variously as "central-Pacific El Niño," "warm-pool El Niño," "dateline El Niño" or "El Niño Modoki" (Japanese for "similar but different"), the maximum ocean warming from such El Niños is found in the central-equatorial, rather than eastern, Pacific. Such central Pacific El Niño events were observed in 1991-92, 1994-95, 2002-03, 2004-05 and 2009-10. A recent study found many climate models predict such events will become much more frequent under projected global warming scenarios.
Lee said further research is needed to evaluate the impacts of these increasingly intense El Niños and determine why these changes are occurring. "It is important to know if the increasing intensity and frequency of these central Pacific El Niños are due to natural variations in climate or to climate change caused by human-produced greenhouse gas emissions," he said.
Results of the study were published recently in Geophysical Research Letters.
For more information visit http://www.nasa.gov/topics/earth/features/elnino20100825.html
useful links: Ferrini Boots, boy suits, Alligator boots
9:13 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
James Cameron, director of "Avatar," the most successful film ever released, is featured in a series of new NASA public service announcements that describe the many contributions of the agency's Earth science program to environmental awareness and exploration of our home planet.
"When NASA ventures into space, it remembers to keep a steady eye on home," Cameron said. "Its fleet of Earth-orbiting satellites constantly reveals our whole planet: its remotest places, its mysteries and the powerful influence of humans."
Cameron's 3-D epic, based on the fictional planet of Pandora is coming back to theaters this week. The story centers on a beautiful planet threatened by forces that want to exploit its natural resources.
The public service announcements feature "Avatar" film imagery and include computer animations and data from NASA's fleet of Earth-observing satellites. NASA has 14 science satellites in orbit making cutting-edge global observations of the entire global system including the atmosphere, oceans, land surface, snow and ice.
'Part of the Global Network'
For more information visit http://www.nasa.gov/topics/earth/features/avatar.html
12:20 AM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
Tight double-star systems might not be the best places for life to spring up, according to a new study using data from NASA's Spitzer Space Telescope. The infrared observatory spotted a surprisingly large amount of dust around three mature, close-orbiting star pairs. Where did the dust come from? Astronomers say it might be the aftermath of tremendous planetary collisions.
"This is real-life science fiction," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. "Our data tell us that planets in these systems might not be so lucky -- collisions could be common. It's theoretically possible that habitable planets could exist around these types of stars, so if there happened to be any life there, it could be doomed."
Drake is the principal investigator of the research, published in the Aug.19 issue of the Astrophysical Journal Letters.
The particular class of binary, or double, stars in the study are about as snug as stars get. Named RS Canum Venaticorums, or RS CVns for short, they are separated by only about two million miles (3.2 million kilometers), or two percent of the distance between Earth and our sun. The stellar pairs orbit around each other every few days, with one face on each star perpetually locked and pointed toward the other.
The close-knit stars are similar to the sun in size and are probably about a billion to a few billion years old -- roughly the age of our sun when life first evolved on Earth. But these stars spin much faster, and, as a result, have powerful magnetic fields, and giant, dark spots. The magnetic activity drives strong stellar winds -- gale-force versions of the solar wind -- that slow the stars down, pulling the twirling duos closer over time. And this is where the planetary chaos may begin.
As the stars cozy up to each other, their gravitational influences change, and this could cause disturbances to planetary bodies orbiting around both stars. Comets and any planets that may exist in the systems would start jostling about and banging into each other, sometimes in powerful collisions. This includes planets that could theoretically be circling in the double stars' habitable zone, a region where temperatures would allow liquid water to exist. Though no habitable planets have been discovered around any stars beyond our sun at this point in time, tight double-star systems are known to host planets; for example, one system not in the study, called HW Vir, has two gas-giant planets.
"These kinds of systems paint a picture of the late stages in the lives of planetary systems," said Marc Kuchner, a co-author from NASA Goddard Space Flight Center in Greenbelt, Md. "And it's a future that's messy and violent."
Spitzer spotted the infrared glow of hot dusty disks, about the temperature of molten lava, around three such tight binary systems. One of the systems was originally flagged as having a suspicious excess of infrared light in 1983 by the Infrared Astronomical Satellite. In addition, researchers using Spitzer recently found a warm disk of debris around another star that turned out to be a tight binary system.
The astronomy team says that dust normally would have dissipated and blown away from the stars by this mature stage in their lives. They conclude that something -- most likely planetary collisions -- must therefore be kicking up the fresh dust. In addition, because dusty disks have now been found around four, older binary systems, the scientists know that the observations are not a fluke. Something chaotic is very likely going on.
If any life forms did exist in these star systems, and they could look up at the sky, they would have quite a view. Marco Matranga, first author of the paper, from the Harvard-Smithsonian Center for Astrophysics and now a visiting astronomer at the Palermo Astronomical Observatory in Sicily, said, "The skies there would have two huge suns, like the ones above the planet Tatooine in 'Star Wars.'"
Other authors include V.L. Kashyap of the Harvard-Smithsonian Center for Astrophysics; and Massimo Marengo of Iowa State University, Ames.
The Spitzer observations were made before it ran out of its liquid coolant in May 2009, officially beginning its warm mission.
NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA.
For More information visit http://www.nasa.gov/mission_pages/spitzer/news/spitzer20100823.html
useful links: Ferrini Boots, boy suits, Alligator boots
9:16 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
NASA is developing technologies that will allow landing vehicles to automatically identify and navigate to the location of a safe landing site while detecting landing hazards during the final descent to the surface. This is important because future missions -- whether to the Moon, an asteroid, Mars or other location -- will need this capability to land safely near specific resources that are located in potentially hazardous terrain.
Langley Research Center, Hampton, Va., has designed three light detection and ranging (lidar) sensors that together can provide all the necessary data for achieving safe autonomous precision landing.
One is a three-dimensional active imaging device, referred to as flash lidar, for detecting hazardous terrain features and identifying safe landing sites. The second is a Doppler lidar instrument for measuring the vehicle velocity and altitude to help land precisely at the chosen site. The third is a high-altitude laser altimeter providing data prior to final approach for correcting the flight trajectory towards the designated landing area.
In conjunction with laser/lidar sensor development at Langley, NASA's Jet Propulsion Laboratory, Pasadena, Calif., is developing algorithms, or mathematical procedures, for analyzing the acquired three-dimensional lidar maps and determining the most suitable landing site. The resulting Doppler lidar and laser altimeter data are used by the navigation system being developed by NASA Johnson Space Center, Houston, and Charles Draper Laboratory, Cambridge, Mass., to control the spacecraft to the identified location.
These technologies have been integrated as part of NASA's Autonomous Landing and Hazard Avoidance Technology (ALHAT) project and are in the process of being demonstrated in a series of flight tests.
The most recent flight tests occurred at NASA's Dryden Flight Research Center, Edwards, Calif., in July.
"These were the first tests where we had all three of our laser systems on board and working together as a complete sensor suite," said Langley's Farzin Amzajerdian, technical lead for development of the sensors. "These tests are being viewed as critical by many within NASA."
Robert Reisse, Langley project manager, added, "We were pleased that the flight tests we've conducted so far have resulted in better than expected performance of these sensors."
The main objective of the first test, carried out in May 2008, was to demonstrate the application of 3-D imaging technology, or 'flash' lidar, for topography mapping and hazard detection.
The second round of flight tests, completed in August 2008, was to evaluate the capabilities of the Doppler lidar. This lidar provides high reliability vehicle velocity vector, altitude and attitude with about two orders of magnitude higher precision than radars.
The third flight test campaign was conducted in June 2009 in which the flash lidar and laser altimeter were integrated and flown onboard a fixed-wing aircraft to assess its performance for terrain relative navigation and altimetry functions. Several flights were performed in areas of Death Valley and in the Nevada Test Site with various flight profiles and altitudes reaching more than five miles above ground level. Locations were selected primarily because of topographical similarities to the lunar terrain.
For the most recent field test, a Sikorsky S-64 helicopter carried all three lidar systems in a pod along with their support instruments. The flash lidar was mounted on a gimbal controlled by the ALHAT processor box that included a navigation filter built specifically for ALHAT by Draper Labs and a human interface module built by NASA Johnson. The processor box also included a 3-D elevation map generator developed by NASA JPL.
NASA Johnson leads the eight-year ALHAT task, begun in early 2006, for NASA's Exploration Technology Development Program. Support is also provided by Draper Labs and the Johns Hopkins Applied Physics Laboratory, Baltimore.
For More information visit http://www.nasa.gov/exploration/features/alhat.html
useful links: Ferrini Boots, boy suits, Alligator boots
10:23 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
In late July 2010, flooding caused by heavy monsoon rains began across several regions of Pakistan. According to the Associated Press, the floods have affected about one-fifth of this country of more than 170 million. Tens of thousands of villages have been flooded, more than 1,500 people have been killed, and millions have been left homeless. The floodwaters are not expected to recede fully before late August.
NASA's CloudSat satellite captured the genesis of the flooding event as it flew over the region on July 28, 2010. At that time, a large area of intense thunderstorms covered much of Pakistan. Between July 28 and 29, up to 400 millimeters (16 inches) of rain fell from these storm cells, triggering flooding along the Indus and Kabul Rivers. Storms with similar structures to this one have become common this summer as tropical monsoon moisture, coupled with a strengthening La Nina (which has different effects around the world), dominate this region's weather patterns.
A series of NASA images shows the anatomy of the flood disaster. Click here to view all five images.
The top portion of the first image, from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua spacecraft, reveals the bright white cloud tops of the cluster of thunderstorms. The blue vertical line shows CloudSat's path at the time the MODIS image was acquired. CloudSat's path cut through a large thunderstorm cell in the northern section of the country.
The Cloudsat data are shown in the bottom portion of the first image. As seen in the top half of the bottom image, CloudSat classified the majority of the clouds present at the time as deep convective (cumulonimbus) clouds, typical of thunderstorms. The bottom half of the lower image shows the 3-D vertical structure of the storm along the satellite's flight path, revealing its heavy precipitation. CloudSat measured the cloud heights along the radar's flight path at around 15 kilometers (9.3 miles) in the areas of deepest convection.
The next pair of images was taken by the vertical-viewing camera on the Multi-angle Imaging Spectroradiometer (MISR) instrument aboard NASA's Terra spacecraft. The image on the left was taken Aug. 8, 2009, while the one on the right is from Aug. 11, 2010. These false-color views display the instrument's near-infrared, red and green bands as shades of red, green and blue. The colors distinctly highlight the contrast between water and vegetation on the river banks, since vegetation appears bright in the near-infrared portion of the electromagnetic spectrum.
The region of southern Pakistan shown here includes the Sindh Province. The Indus River, Pakistan's longest, can be seen snaking across the image from lower left to upper right. The feature near the bottom and left of center is Manchhar Lake. Water appears as shades of blue and cyan, though sediment content can add a tan color, as seen in the upper right. Clouds appear white. In the image from 2009, the Indus is typically about 1 kilometer (0.6 miles) wide. In contrast, in the 2010 image, the river is around 23 kilometers (14 miles) wide in spots, and flooding is very evident in much of the surrounding region, particularly in the Larkana District west of the river.
A different before-and-after perspective of the floods is provided by the next pair of false-color images, taken by the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua spacecraft using its four visible and near-infrared channels. These images also show southern Pakistan and the Sindh Province. The Indus River appears to enter from the upper right and winds its way southwestward toward the lower left. The image at the left was taken before the flooding on July 9, 2010, while the right-hand image was taken on Aug. 10, 2010.
The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft provides the next image, a cloud-free view over the city of Sukkur, Pakistan, taken on Aug. 18, 2010. Sukkur, a city of a half million residents in southeastern Pakistan's Sindh Province, is visible as the gray, urbanized area in the lower left center of the image. It lies along the Indus River, which snakes vertically from north to south through the image and forms the basis for the world's largest canal-based irrigation system. As reported by the British Broadcasting Corporation, Sukkur is one of the few urban areas in the region that has so far escaped widespread destruction from the flooding, which has affected an estimated 4 million people in the province. Relief camps have sprung up across the city to house some of these displaced people. The land along the Indus River in this region is largely agricultural, and the flooding has taken a heavy toll on the region's crops and fruit trees.
The final image was created with data from the Advanced Microwave Sounding Unit instrument, which flies on NASA's Aqua spacecraft as part of the AIRS instrument suite. It shows how surface emissivity-how efficiently Earth's surface radiates heat-changed in the affected region over a 32-day period between July 11 and August 12. Surface emission, in this case in the microwave region of the electromagnetic spectrum, depends strongly on what type of surface is present. For dry land, surface emission is high-measuring close to 1 (land radiates heat very efficiently); while for water, it is quite low-measuring less than 0.5 (water tends to retain heat better than land). The image shows that the emission dropped over this time span by up to 0.4 in large areas surrounding the Indus River, indicating that these areas are almost completely underwater.
Scientists can use this technique to estimate how much of the land surface has been inundated. A significant advantage is that the technique works both day and night, and under both clear and cloudy conditions.
For more information visit http://www.jpl.nasa.gov/news/news.cfm?release=2010-274
useful links: Ferrini Boots, boy suits, Alligator boots
9:42 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
Astronomers have devised a new method for measuring perhaps the greatest puzzle of our universe -- dark energy. This mysterious force, discovered in 1998, is pushing our universe apart at ever-increasing speeds.
For the first time, astronomers using NASA's Hubble Space Telescope were able to take advantage of a giant magnifying lens in space -- a massive cluster of galaxies -- to narrow in on the nature of dark energy. Their calculations, when combined with data from other methods, significantly increase the accuracy of dark energy measurements. This may eventually lead to an explanation of what the elusive phenomenon really is.
"We have to tackle the dark energy problem from all sides," said Eric Jullo, an astronomer at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It's important to have several methods, and now we've got a new, very powerful one." Jullo is lead author of a paper on the findings appearing in the Aug. 20 issue of the journal Science.
Scientists aren't clear about what dark energy is, but they do know that it makes up a large chunk of our universe -- about 72 percent. Another chunk, about 24 percent, is thought to be dark matter, also mysterious in nature but easier to study than dark energy because of its gravitational influence on matter that we can see. The rest of the universe, a mere four percent, is the stuff that makes up people, planets, stars and everything made up of atoms.
In their new study, the science team used images from Hubble to examine a massive cluster of galaxies, named Abell 1689, which acts as a magnifying, or gravitational, lens. The gravity of the cluster causes galaxies behind it to be imaged multiple times into distorted shapes, sort of like a fun house mirror reflection that warps your face.
Using these distorted images, the scientists were able to figure out how light from the more distant, background galaxies had been bent by the cluster -- a characteristic that depends on the nature of dark energy. Their method also depends on precise ground-based measurements of the distance and speed at which the background galaxies are traveling away from us. The team used these data to quantify the strength of the dark energy that is causing our universe to accelerate.
"What I like about our new method is that it's very visual," said Jullo. "You can literally see gravitation and dark energy bend the images of the background galaxies into arcs."
According to the scientists, their method required multiple, meticulous steps. They spent the last several years developing specialized mathematical models and precise maps of the matter -- both dark and "normal" -- constituting the Abell 1689 cluster.
"We can now apply our technique to other gravitational lenses," said co-author Priya Natarajan, a cosmologist at Yale University, New Haven, Conn. "We're exploiting a beautiful phenomenon in nature to learn more about the role that dark energy plays in our universe."
Other authors of the paper include Jean-Paul Kneib and Carlo Schimd of the Université de Provence, France; Anson D'Aloisio of Yale University; Marceau Limousin of Université de Provence and University of Copenhagen, Denmark; and Johan Richard of Durham University, United Kingdom.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute, operated for NASA by the Association of Universities for Research in Astronomy, Inc. in Washington, conducts Hubble science operations.
For more information visit http://www.jpl.nasa.gov/news/news.cfm?release=2010-272
useful links: Ferrini Boots, boy suits, Alligator boots
9:49 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
Imagine floating 35,000 miles above the sunny side of Earth. Our home planet gleams below, a majestic whorl of color and texture. All seems calm around you. With no satellites or space debris to dodge, you can just relax and enjoy the black emptiness of space.
But looks can be deceiving.
In reality, you've unknowingly jumped into an invisible mosh pit of electromagnetic mayhem — the place in space where a supersonic "wind" of charged particles from the Sun crashes head-on into the protective magnetic bubble that surrounds our planet. Traveling at a million miles per hour, the solar wind's protons and electrons sense Earth's magnetosphere too late to flow smoothly around it. Instead, they're shocked, heated, and slowed almost to a stop as they pile up along its outer boundary, the magnetopause, before getting diverted sideways.
Space physicists have had a general sense of these dynamic goings-on for decades. But it wasn't until the advent of the Interstellar Boundary Explorer or IBEX, a NASA spacecraft launched in October 2008, that they've been able to see what the human eye cannot: the first-ever images of this electromagnetic crash scene. They can now witness how some of the solar wind's charged particles are being neutralized by gas escaping from Earth's atmosphere.
A New Way to See Atoms
IBEX wasn't designed to keep tabs on Earth's magnetosphere. Instead, its job is to map interactions occurring far beyond the planets, 8 to 10 billion miles away, where the Sun's own magnetic bubble, the heliosphere, meets interstellar space.
Only two spacecraft, Voyagers 1 and 2, have ventured far enough to probe this region directly. IBEX, which travels in a looping, 8-day-long orbit around Earth, stays much closer to home, but it carries a pair of detectors that can observe the interaction region from afar.
Here's how: When fast-moving protons in the solar wind reach the edge of the heliosphere, they sometimes grab electrons from the slower-moving interstellar atoms around them, like batons getting passed between relay runners. This charge exchange creates electrically neutral hydrogen atoms that are no longer controlled by magnetic fields. Suddenly, they're free to go wherever they want — and because they're still moving fast, they quickly zip away from the interstellar boundary in all directions.
Some of these "energetic neutral atoms," or ENAs, zip past Earth, where they're recorded by IBEX. Its two detectors don't take pictures with conventional optics. Instead, they record the number and energy of atoms arriving from small spots of sky about 7 degrees across (the apparent size of a tennis ball held at arm's length). Because its spin axis always points at the Sun, the spacecraft slowly turns throughout Earth's orbit and its detectors scan overlapping strips that create a complete 360 degrees map every six months.
A Collision Zone Near Earth
Because IBEX is orbiting Earth, it also has a front-row seat for observing the chaotic pileup of solar-wind particles occurring along the "nose" of Earth's magnetopause, about 35,000 miles out. ENAs are created there too, as solar-wind protons wrest electrons from hydrogen atoms in the outermost vestiges of our atmosphere, the exosphere.
Other spacecraft have attempted to measure the density of the dayside exosphere, without much success. NASA's Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft probably detected ENAs from this region a decade ago, but its detectors didn't have the sensitivity to pinpoint or measure the source.
Now, thanks to IBEX, we know just how tenuous the outer exosphere really is. "Where the interaction is strongest, there are only about eight hydrogen atoms per cubic centimeter," explains Stephen A. Fuselier, the Lockheed Martin Space Systems researcher who led the mapping effort. His team's results appear in the July 8 issue of Geophysical Research Letters.
The key observations were made in March and April 2009, when IBEX was located far from Earth — about halfway to the Moon's orbit — and its detectors could scan the region directly in front of the magnetopause. During some of the March observations, the European Space Agency's Cluster 3 spacecraft was positioned just in front of the magnetopause, where it measured the number of deflected solar-wind protons directly. "Cluster played a very important role in this study," Fuselier explains. "It was in the right place at the right time."
The new IBEX maps show that the ENAs thin out at locations away from the point of peak intensity. This falloff makes sense, Fuselier says, because Earth's magnetopause isn't spherical. Instead, it has a teardrop shape that's closest to Earth at its nose but farther away everywhere else. So at locations well away from the magnetopause's centerline, even fewer of the exosphere's hydrogen atoms are hanging around to interact with the solar wind. "No exosphere, no ENAs," he explains.
A Versatile Spacecraft
Since its launch, IBEX has also scanned another nearby world, with surprising results. The moon has no atmosphere or magnetosphere, so the solar wind slams unimpeded into its desolate surface. Most of those particles get absorbed by lunar dust. In fact, space visionaries wonder if the moon's rubbly surface has captured enough helium-3, an isotope present in tiny amounts in the Sun's outflow, to serve as a fuel for future explorers.
Yet cosmic chemists have long thought that some solar-wind protons must be bouncing off the lunar surface, becoming ENAs through charge exchange as they do. So does the moon glow in IBEX's scans? Indeed it does, says David J. McComas of Southwest Research Institute in San Antonio, Texas, who serves as the mission's Principal Investigator.
In a report published last year in Geophysical Research Letters, McComas and other researchers conclude that about 10 percent of the solar-wind particles striking the Moon escape to space as ENAs detectable by IBEX. That amounts to roughly 150 tons of recycled hydrogen atoms per year.
Meanwhile, the squat, eight-sided spacecraft continues its primary task of mapping the interactions between the outermost heliosphere and the interstellar medium that lies beyond. McComas and his team are especially eager to learn more about the mysterious and unexpected "ribbon" of ENAs that turned up in the spacecraft's initial all-sky map.
At NASA's Goddard Space Flight Center in Greenbelt, Md., IBEX Mission Scientist Robert MacDowall says the spacecraft should be able to continue its observations through at least 2012. "We weren't sure those heliospheric interactions would vary with time, but they do," he explains, "and it's great that IBEX will be able to record them for years to come."
For more information visit http://www.nasa.gov/mission_pages/ibex/em-crash.html
useful links: Ferrini Boots, boy suits, Alligator boots
9:49 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
NASA's Cassini spacecraft has successfully completed its flyby over the "tiger stripes" in the south polar region of Saturn's moon Enceladus and has sent back images of its passage. The spacecraft also targeted the moon Tethys.
The tiger stripes are actually giant fissures that spew jets of water vapor and organic particles hundreds of kilometers, or miles, out into space. While the winter is darkening the moon's southern hemisphere, Cassini has its own version of "night vision goggles" -- the composite infrared spectrometer instrument - to track heat even when visible light is low. It will take time for scientists to assemble the data into temperature maps of the fissures.
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 Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL.
For More information visit http://www.jpl.nasa.gov/news/news.cfm?release=2010-269
useful links: Ferrini Boots, boy suits, Alligator boots
9:44 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
Astronomers using NASA's Fermi Gamma-ray Space Telescope have detected gamma-rays from a nova for the first time, a finding that stunned observers and theorists alike. The discovery overturns the notion that novae explosions lack the power to emit such high-energy radiation.
A nova is a sudden, short-lived brightening of an otherwise inconspicuous star. The outburst occurs when a white dwarf in a binary system erupts in an enormous thermonuclear explosion.
"In human terms, this was an immensely powerful eruption, equivalent to about 1,000 times the energy emitted by the sun every year," said Elizabeth Hays, a Fermi deputy project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "But compared to other cosmic events Fermi sees, it was quite modest. We're amazed that Fermi detected it so strongly."
Gamma rays are the most energetic form of light, and Fermi's Large Area Telescope (LAT) detected the nova for 15 days. Scientists believe the emission arose as a million-mile-per-hour shock wave raced from the site of the explosion.
A paper detailing the discovery will appear in the Aug. 13 edition of the journal Science.
The story opened in Japan during the predawn hours of March 11, when amateur astronomers Koichi Nishiyama and Fujio Kabashima in Miyaki-cho, Saga Prefecture, imaged a dramatic change in the brightness of a star in the constellation Cygnus. They realized that the star, known as V407 Cyg, was 10 times brighter than in an image they had taken three days earlier.
The team relayed the nova discovery to Hiroyuki Maehara at Kyoto University, who notified astronomers around the world for follow-up observations. Before this notice became widely available, the outburst was independently reported by three other Japanese amateurs: Tadashi Kojima, Tsumagoi-mura Agatsuma-gun, Gunma prefecture; Kazuo Sakaniwa, Higashichikuma-gun, Nagano prefecture; and Akihiko Tago, Tsuyama-shi, Okayama prefecture.
On March 13, Goddard's Davide Donato was on-duty as the LAT "flare advocate," a scientist who monitors the daily data downloads for sources of potential interest, when he noticed a significant detection in Cygnus. But linking this source to the nova would take several days, in part because key members of the Fermi team were in Paris for a meeting of the LAT scientific collaboration.
"This region is close to the galactic plane, which packs together many types of gamma-ray sources -- pulsars, supernova remnants, and others in our own galaxy, plus active galaxies beyond them," Donato said. "If the nova had occurred elsewhere in the sky, figuring out the connection would have been easier."
The LAT team began a concerted effort to identify the mystery source over the following days. On March 17, the researchers decided to obtain a "target-of-opportunity" observation using NASA's Swift satellite -- only to find that Swift was already observing the same spot.
"At that point, I knew Swift was targeting V407 Cyg, but I didn't know why," said Teddy Cheung, an astrophysicist at the Naval Research Laboratory (NRL) in Washington, D.C., and the lead author of the study. Examining the Swift data, Cheung saw no additional X-ray sources that could account for what Fermi's LAT was seeing.
V407 Cyg had to be it.
Half an hour later, Cheung learned from other members of the LAT team that the system had undergone a nova outburst, which was the reason the Swift observations had been triggered. "When we looked closer, we found that the LAT had detected the first gamma rays at about the same time as the nova's discovery," he said.
V407 Cyg lies 9,000 light-years away. The system is a so-called symbiotic binary containing a compact white dwarf and a red giant star about 500 times the size of the sun.
"The red giant is so swollen that its outermost atmosphere is just leaking away into space," said Adam Hill at Joseph Fourier University in Grenoble, France. The phenomenon is similar to the solar wind produced by the sun, but the flow is much stronger. "Each decade, the red giant sheds enough hydrogen gas to equal the mass of Earth," he added.
The white dwarf intercepts and captures some of this gas, which accumulates on its surface. As the gas piles on for decades to centuries, it eventually becomes hot and dense enough to fuse into helium. This energy-producing process triggers a runaway reaction that explodes the accumulated gas.
The white dwarf itself, however, remains intact.
The blast created a hot, dense expanding shell called a shock front, composed of high-speed particles, ionized gas and magnetic fields. According to an early spectrum obtained by Christian Buil at Castanet Tolosan Observatory, France, the nova's shock wave expanded at 7 million miles per hour -- or nearly 1 percent the speed of light.
The magnetic fields trapped particles within the shell and whipped them up to tremendous energies. Before they could escape, the particles had reached velocities near the speed of light. Scientists say that the gamma rays likely resulted when these accelerated particles smashed into the red giant's wind.
"We know that the remnants of much more powerful supernova explosions can trap and accelerate particles like this, but no one suspected that the magnetic fields in novae were strong enough to do it as well," said NRL's Soebur Razzaque.
Supernovae remnants endure for 100,000 years and affect regions of space thousands of light-years across.
Kent Wood at NRL compares astronomical studies of supernova remnants to looking at static images in a photo album. "It takes thousands of years for supernova remnants to evolve, but with this nova we've watched the same kinds of changes over just a few days," he said. "We've gone from a photo album to a time-lapse movie."
For more information visit http://www.nasa.gov/mission_pages/GLAST/news/shocking-nova.html
9:29 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
Astronomers have found mysterious, giant loops of ultraviolet light in aged, massive galaxies, which seem to have a second lease on life. Somehow these "over-the-hill galaxies" have been infused with fresh gas to form new stars that power these truly gargantuan rings, some of which could encircle several Milky Way galaxies.
The discovery of these rings implies that bloated galaxies presumed "dead" and devoid of star-making can be reignited with star birth, and that galaxy evolution does not proceed straight from the cradle to the grave.
"In a galaxy's lifetime, it must make the transition from an active, star-forming galaxy to a quiescent galaxy that does not form stars," said Samir Salim, lead author of a recent study and a research scientist in the department of astronomy at Indiana University, Bloomington. "But it is possible this process goes the other way, too, and that old galaxies can be rejuvenated."
A One-Two Observational Punch
The findings come courtesy of the combined power of two orbiting observatories, NASA's Galaxy Evolution Explorer and Hubble Space Telescope. First, the Galaxy Evolution Explorer surveyed a vast region of the sky in ultraviolet light. The satellite picked out 30 elliptical and lens-shaped "early" galaxies with puzzlingly strong ultraviolet emissions but no signs of visible star formation. Early-type galaxies, so the scientists' thinking goes, have already made their stars and now lack the cold gas necessary to build new ones.
The Galaxy Evolution Explorer could not discern the fine details of these large, rounded galaxies gleaming in the ultraviolet, so to get a closer look, researchers turned to the Hubble Space Telescope. What they saw shocked them: three-quarters of the galaxies were spanned by great, shining rings of ultraviolet light, with some ripples stretching 250,000 light-years. A few galaxies even had spiral-shaped ultraviolet features.
"We haven't seen anything quite like these rings before," said Michael Rich, co-author of the paper and a research astronomer at UCLA. "These beautiful and very unusual objects might be telling us something very important about the evolution of galaxies."
Colors of the Ages
Astronomers can tell a galaxy's approximate age just by the color of its collective starlight. Lively, young galaxies look bluish to our eyes due to the energetic starlight of their new, massive stars. Elderly galaxies instead glow in the reddish hues of their ancient stars, appearing "old, red and dead," as astronomers bluntly say. Gauging by the redness of their constituent stars, the galaxies seen by the Galaxy Evolution Explorer and Hubble are geezers, with most stars around 10 billion years old.
But relying on the spectrum of light visible to the human eye can be deceiving, as some of us have found out after spending a day under the sun's invisible ultraviolet rays and getting a sunburn. Sure enough, when viewed in the ultraviolet part of the spectrum, these galaxies clearly have more going on than meets the eye.
Some ultraviolet starlight in a few of the observed galaxies might just be left over from an initial burst of star formation. But in most cases, new episodes of star birth must be behind the resplendent rings, meaning that fresh gas has somehow been introduced to these apparently ancient galaxies. Other telltale signs of ongoing star formation, such as blazing hydrogen gas clouds, might be on the scene as well, but have so far escaped detection.
The Lord of the Ultraviolet Rings
Just where the gas for this galactic resurrection came from and how it has created rings remains somewhat perplexing. A merging with a smaller galaxy would bring in fresh gas to spawn hordes of new stars, and could in rare instances give rise to the ring structures as well.
But the researchers have their doubts about this origin scenario. "To create a density shock wave that forms rings like those we've seen, a small galaxy has to hit a larger galaxy pretty much straight in the center," said Salim. "You have to have a dead-on collision, and that's very uncommon."
Rather, the rejuvenating spark more likely came from a gradual sopping-up of the gas in the so-called intergalactic medium, the thin soup of material between galaxies. This external gas could generate these rings, especially in the presence of bar-like structures that span some galaxies' centers.
Ultimately, more observations will be needed to show how these galaxies began growing younger and lit up with humongous halos. Salim and Rich plan to search for more evidence of bars, as well as faint structures that might be the remnants of stellar blooms that occurred in the galaxies' pasts. Rather like recurring seasons, it may be that galaxies stirred from winter can breed stars again and then bask in another vibrant, ultraviolet-soaked summer.
The study detailing the findings appeared in the April 21 issue of the Astrophysical Journal.
The California Institute of Technology in Pasadena leads the Galaxy Evolution Explorer mission and is responsible for science operations and data analysis. NASA's Jet Propulsion Laboratory, also in Pasadena, manages the mission and built the science instrument. The mission was developed under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. Researchers sponsored by Yonsei University in South Korea and the Centre National d'Etudes Spatiales (CNES) in France collaborated on this mission.
For more information visit http://www.jpl.nasa.gov/news/news.cfm?release=2010-264
useful links: Ferrini Boots, boy suits, Alligator boots
10:53 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
NASA's Wide-field Infrared Survey Explorer, or WISE, is warming up. Team members say the spacecraft is running out of the frozen coolant needed to keep its heat-sensitive instrument chilled.
The telescope has two coolant tanks that keep the spacecraft's normal operating temperature at 12 Kelvin (minus 438 degrees Fahrenheit). The outer, secondary tank is now depleted, causing the temperature to increase. One of WISE's infrared detectors, the longest-wavelength band most sensitive to heat, stopped producing useful data once the telescope warmed to 31 Kelvin (minus 404 degrees Fahrenheit). The primary tank still has a healthy supply of coolant, and data quality from the remaining infrared detectors remains high.
WISE completed its primary mission, a full scan of the entire sky in infrared light, on July 17, 2010. The mission has taken more than 1.5 million snapshots so far, uncovering hundreds of millions of objects, including asteroids, stars and galaxies. It has discovered more than 29,000 new asteroids to date, more than 100 near-Earth objects and 15 comets.
WISE is continuing a second survey of about one-half the sky as originally planned. It’s possible the remaining coolant will run out before that scan is finished. Scientists say the second scan will help identify new and nearby objects, as well as those that have changed in brightness. It could also help to confirm oddball objects picked up in the first scan.
NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program, managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.
For more information visit http://www.jpl.nasa.gov/news/news.cfm?release=2010-263
useful links: Ferrini Boots, boy suits, Alligator boots
10:18 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
On Aug. 5, 2010, an enormous chunk of ice, roughly 97 square miles (251 square kilometers) in size, broke off the Petermann Glacier, along the northwestern coast of Greenland. The Canadian Ice Service detected the remote event within hours in near real-time data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite. The Petermann Glacier lost about one-quarter of its 70-kilometer (40-mile) long floating ice shelf, said researchers who analyzed the satellite data at the University of Delaware.
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured these natural-color images of Petermann Glacier 18:05 UTC on August 5, 2010 (top), and 17:15 UTC on July 28, 2010 (bottom). The Terra image of the Petermann Glacier on August 5 was acquired almost 10 hours after the Aqua observation that first recorded the event. By the time Terra took this image, skies were less cloudy than they had been earlier in the day, and the oblong iceberg had broken free of the glacier and moved a short distance down the fjord.
Icebergs calving off the Petermann Glacier are not unusual. Petermann Glacier’s floating ice tongue is the Northern Hemisphere’s largest, and it has occasionally calved large icebergs. The recently calved iceberg is the largest to form in the Arctic since 1962, said the University of Delaware.
Map of Greenland showing approximate location of Petermann Glacier.
10:56 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
Side-by-side comparison of carbon monoxide pollution from the series of devastating wildfires burning across central and western Russia, as seen by the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua spacecraft on July 21, 2010 (left) and Aug. 1, 2010 (right). The AIRS data show the abundance of carbon monoxide present in the atmosphere at an altitude of 5.5 kilometers (18,000 feet). Image credit: NASA/JPL/Leonid Yurganov, University of Maryland, Baltimore County - Larger view
Drought and the worst heat wave Russia has seen in 130 years have sparked a devastating outbreak of wildfires across the nation this summer, primarily in the country's western and central regions. According to wire service reports and Russia's Emergency Situations Ministry, as of Aug. 6, 2010, some 558 fires were burning. The fires have killed at least 52 people, destroyed some 2,000 homes and charred more than 1,796 square kilometers (693 square miles). Russia's capital city of Moscow is currently blanketed in a thick smog, which has curtailed activities and disrupted air traffic. According to the Associated Press, levels of carbon monoxide pollution in Moscow are at an all-time high, four times higher than normal.
The Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua spacecraft is tracking the concentration and transport of carbon monoxide from the Russian fires. The figures presented here show the abundance of carbon monoxide present in the atmosphere at an altitude of 5.5 kilometers (18,000 feet). AIRS is sensitive to carbon monoxide in the mid-troposphere at heights between 2 and 10 kilometers (1.2 and 6.2 miles), with a peak sensitivity at an altitude of approximately 5 kilometers (3.1 miles). This region of Earth's atmosphere is also conducive to the long-range transport of the pollution that is lofted to this altitude.
As shown in Figure 1, acquired July 21, 2010, the concentration of carbon monoxide from the fires on that date was largely limited to the European part of Russia (western and central Russia). This contrasts dramatically with the data in Figure 2, acquired on August 1, when the carbon monoxide concentration was much higher and the area of the fires had increased significantly. The concentration of carbon monoxide is continuing to grow. According to Aug. 4 NASA estimates, the smoke plume from the fires spans about 3,000 kilometers (1,860 miles) from east to west, approximately the distance from San Francisco to Chicago.
Figure 3 shows changes in the total amount of carbon monoxide above western Russia in megatons through August 1, 2010 (shown by the red curve). The changes are plotted again the base year of 2009, which saw normal levels of seasonal carbon monoxide. This is contrasted against the year 2002, when peat fires predominated in Russia. The 2002 data are from the Measurements of Pollution in the Troposphere (MOPITT) instrument on NASA's Terra spacecraft. On August 1, 2010, the excess carbon monoxide content almost reached the maximum values seen in 2002. The rate of growth (approximately 0.7 megatons, or 700,000 metric tons, per day) characterizes the rate of emission; the current rate is approximately three times higher than in 2002.
AIRS is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.
For more information visit http://www.jpl.nasa.gov/news/news.cfm?release=2010-261
useful links: Ferrini Boots, boy suits, Alligator boots
9:00 PM
Gabriella Brianna
, Posted in
NASA News
,
0 Comments
A Geminid meteor. Image credit: Jimmy Westlake - Larger image
There are several major meteor showers to enjoy every year at various times, with some more active than others. For example, April's Lyrids are expected to produce about 15 meteors an hour at their peak for observers viewing in good conditions. Now, if you put the same observer in the same good conditions during a higher-rate shower like August's Perseids or December's Geminids, that person could witness up to 80 meteors an hour during peak activity.
Whether you're watching from a downtown area or the dark countryside, here are some tips to help you enjoy these celestial shows of shooting stars. Those streaks of light are really caused by tiny specks of comet-stuff hitting Earth's atmosphere at very high speed and disintegrating in flashes of light.
First a word about the moon - it is not the meteor watcher's friend. Light reflecting off a bright moon can be just as detrimental to good meteor viewing as those bright lights of the big city. There is nothing you can do except howl at the moon, so you'll have to put up with it or wait until the next favorable shower. However, even though the 2010 Perseids and Geminids share the night sky with the moon, they are still expected to produce more visible meteor activity than other major showers that don't have an interfering moon.
The best thing you can do to maximize the number of meteors you'll see is to get as far away from urban light pollution as possible and find a location with a clear, unclouded view of the night sky. If you enjoy camping, try planning a trip that coincides with dates of one of the meteor showers listed below. Once you get to your viewing location, search for the darkest patch of sky you can find, as meteors can appear anywhere overhead. The meteors will always travel in a path away from the constellation for which the shower is named. This apparent point of origin is called the "radiant." For example, meteors during a Leonid meteor shower will appear to originate from the constellation Leo. (Note: the constellation only serves as a helpful guide in the night's sky. The constellation is not the actual source of the meteors. For an overview of what causes meteor showers click on Meteor Showers: Shooting for Shooting Stars)
Whether viewing from your front porch or a mountaintop, be sure to dress for success. This means clothing appropriate for cold overnight temperatures, which might include mittens or gloves, and blankets. This will enable you to settle in without having to abandon the meteor-watching because your fingers are starting to turn colors.
Next, bring something comfortable on which to sit or lie down. While Mother Nature can put on a magnificent celestial display, meteor showers rarely approach anything on the scale of a July 4th fireworks show. Plan to be patient and watch for at least half an hour. A reclining chair or ground pad will make it far more comfortable to keep your gaze on the night sky.
Lastly, put away the telescope or binoculars. Using either reduces the amount of sky you can see at one time, lowering the odds that you'll see anything but darkness. Instead, let your eyes hang loose and don't look in any one specific spot. Relaxed eyes will quickly zone in on any movement up above, and you'll be able to spot more meteors. Avoid looking at your cell phone or any other light. Both destroy night vision. If you have to look at something on Earth, use a red light. Some flashlights have handy interchangeable filters. If you don't have one of those, you can always paint the clear filter with red fingernail polish.
The meteor showers listed below will provide casual meteor observers with the most bang for their buck. They are the easiest to observe and most active. All these showers are best enjoyed in the hours after midnight. Be sure to also check the "Related Links" box for additional information, and for tools to help you determine how many meteors may be visible from your part of the world.
Major Meteor Showers (2010-2011)
Delta Aquarids
Comet of Origin: unknown
Radiant: constellation Aquarius
Active: July 14-Aug. 18, 2010
Peak Activity: No definite peak, but nights surrounding July 30 were predicted to be the best
Peak Activity Meteor Count: Approximately 15 meteors per hour (Northern Hemisphere).
Time of Optimal Viewing: An hour or two before dawn. Meteor watchers in the Southern Hemisphere and in the Northern Hemisphere's tropical latitudes enjoy the best views.
Meteor Velocity: 42 kilometers per second (26 miles per second)
Perseids
Comet of Origin: 109P/Swift-Tuttle
Radiant: constellation Perseus
Active: Perseids begin to rise early August.
Peak Activity: Aug. 12-13, 2010
Peak Activity Meteor Count: Approximately 50 meteors per hour
Time of Optimal Viewing: Crescent moon will set early in the evening, allowing for dark skies all the way up until peak viewing just before dawn
Meteor Velocity: 61 kilometers (38 miles) per second
Note: The Perseid meteor shower is one of the most consistent performers and considered by many as 2010's best shower. The meteors they produce are among the brightest of all meteor showers.
Orionids
Comet of Origin: 1P/Halley
Radiant: Just to the north of constellation Orion's bright star Betelgeuse
Active: Oct. 4-Nov. 14, 2010
Peak Activity: Night of Oct. 22, but the light reflecting off an almost-full moon makes 2010 a less-than-spectacular year for one of Mother Nature's most spectacular showers.
Peak Activity Meteor Count: Approximately 15 meteors per hour, if the sky is dark
Time of Optimal Viewing: An hour or two before dawn
Meteor Velocity: 68 kilometers (42 miles) per second
Note: With the second-fastest entry velocity of the annual meteor showers, meteors from the Orionids produce yellow and green colors and have been known to produce an odd fireball from time to time.
Leonids
Comet of Origin: 55P/Tempel-Tuttle
Radiant: constellation Leo
Active: Nov. 7-28, 2010
Peak Activity: Night of Nov. 17-18, 2010
Peak Activity Meteor Count: Approximately 15 per hour
Time of Optimal Viewing: A half-full moon sets after midnight, allowing for a dark sky. Best viewing time will be just before dawn.
Meteor Velocity: 71 kilometers (44 miles) per second
Note: The Leonids have not only produced some of the best meteor showers in history, but they have sometimes achieved the status of meteor storm. During a Leonid meteor storm, many thousands of meteors per hour can shoot across the sky. Scientists believe these storms recur in cycles of about 33 years, though the reason is unknown. The last documented Leonid meteor storm occurred in 2002.
Geminids
Comet of Origin: 3200 Phaethon
Radiant: constellation Gemini
Active: Dec. 4-16, 2010
Peak Activity: Night of Dec 13-14, 2010
Peak Activity Meteor Count: Approximately 50 meteors per hour
Time of Optimal Viewing: 2 a.m.
Meteor Velocity: 35 kilometers (22 miles) per second
Note: Generally, the Geminids or August's Perseids provide the best meteor shower show of the year. Geminids are usually considered the best opportunity for younger viewers because the show gets going around 9 or 10 p.m. Unfortunately the moon does not set until after midnight this year, making for the possibility of drooping eyelids from the pre-teen set.
Quadrantids
Comet of Origin: 2003 EH1
Radiant: constellation Quadrant Murales
Active: Dec. 28, 2010-Jan. 12, 2011
Peak Activity: Jan. 3-4, 2011
Peak Activity Meteor Count: Approximately 40 meteors per hour
Time of Optimal Viewing: 2:30 a.m. to dawn
Meteor Velocity: 41 kilometers (25.5 miles) per second
Note: The alternate name for the Quadrantids is the Bootids. Constellation Quadrant Murales is now defunct, and the meteors appear to radiate from the modern constellation Bootes. Since the show is usually only a few hours long and often obscured by winter weather, it doesn't have the same celebrated status as the Geminids or Perseids.
Lyrids
Comet of Origin: C/1861 G1 Thatcher
Radiant: constellation Lyra
Active: April 16-25, 2011
Peak Activity: April 21-22, 2011
Peak Activity Meteor Count: 18-20 meteors per hour
Time of Optimal Viewing: 11 p.m.-dawn
Meteor Velocity: Lyrid meteors hit the atmosphere at a moderate speed of 48 kilometers (30 miles) per second. They often produce luminous dust trains observable for several seconds.
Note: Light from the waning gibbous moon will degrade viewing
Eta Aquarids
Comet of Origin: 1P Halley
Radiant: constellation Aquarius
Active: April 19-May 28, 2011
Peak Activity: Early morning May 5-7, 2011
Peak Activity Meteor Count: Approximately 20 meteors per hour
Time of Optimal Viewing: 3:30-5 a.m.
Meteor Velocity: 66 kilometers (44 miles) per second
For more information visit http://www.jpl.nasa.gov/news/news.cfm?release=2010-119
useful links: Ferrini Boots, boy suits, Alligator boots
