8:57 PM
Gabriella Brianna
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Flight Dynamics data from THEMIS-B (one of the two ARTEMIS spacecraft) indicated that one of the EFI (electric field instrument)spherical tip masses may have been struck by a meteoroid at 0605 UT on October 14. All science instruments continue to collect data. The probe and science instruments aboard the spacecraft continue to operate nominally. The upcoming insertion into Lissajous orbit will not be interrupted.
ARTEMIS stands for “Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun”. The ARTEMIS mission uses two of the five in-orbit spacecraft from another NASA Heliophysics constellation of satellites (THEMIS) that were launchedin 2007 and successfully completed their mission earlier in 2010. The ARTEMIS mission allowed NASA to repurpose two in-orbit spacecraft to extend their useful science mission. ARTEMIS will use simultaneous measurements of particles and electric and magnetic fields from two locations to provide the first three-dimensional perspective of how energetic particle acceleration occurs near the Moon's orbit, in the distant magnetosphere, and in the solar wind.
For more information visit thtp://www.nasa.gov/mission_pages/themis/news/artemis-struck.html
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9:22 PM
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The lunar rocks brought back to the Earth by the Apollo astronauts were found to have very little water, and to be much drier than rocks on Earth. An explanation for this was that the Moon formed billions of years ago in the solar system's turbulent youth, when a Mars-sized planet crashed into Earth. The impact stripped away our planet's outer layer, sending it into orbit. The pieces later coalesced under their own gravity to form our Moon. Heat from all this mayhem vaporized most of the water in the lunar material, so the water was lost to space.
However, there was still a chance that water might be found in special places on the Moon. Due to the Moon's orientation to the Sun, scientists theorized that deep craters at the lunar poles would be in permanent shadow and thus extremely cold and able to trap volatile material like water as ice perhaps delivered there by comet impacts or chemical reactions with hydrogen carried by the solar wind.
Last year on October 9, NASA's LCROSS (Lunar Crater Remote Observation and Sensing Satellite) intentionally crashed its companion Centaur upper stage into the Cabeus crater near the lunar south pole. The idea was to kick up debris from the bottom of the crater so its composition could be analyzed. The Centaur hit at over 5,600 miles per hour, sending up a plume of material over 12 miles high.
"Seeing mostly pure water ice grains in the plume means water ice was somehow delivered or chemical processes are causing ice to accumulate in large quantities," said Anthony Colaprete, LCROSS project scientist and principal investigator at NASA's Ames Research Center, Moffett Field, Calif. "Furthermore, the diversity and abundance of certain materials called volatiles in the plume, suggest a variety of sources, like comets and asteroids, and an active water cycle within the lunar shadows."
LCROSS was a companion mission to NASA's Lunar Reconnaissance Orbiter (LRO) mission.
The two missions were designed to work together, and support from LRO was critical to the success of LCROSS. During impact, LRO, which is normally looking at the lunar surface, was tilted toward the horizon so it could observe the plume. Shortly after the Centaur hit the Moon, LRO flew past debris and gas from the impact while its instruments collected data.
"LRO assisted LCROSS in two primary ways -- selecting the impact site and confirming the LCROSS observations," said Gordon Chin of NASA's Goddard Space Flight Center, Greenbelt, Md., LRO associate project scientist.
"Since observatories on Earth were also planning to view the impact, there were a lot of constraints on the location -- the impact plume had to rise out of the crater and into sunlight, and it had to be visible from Earth," said Chin.
Prior to the impact, LRO's instruments worked together to map and provide details on the polar regions, according to Chin. For example, LRO's Lunar Orbiter Laser Altimeter (LOLA) instrument built up three-dimensional (topographic) maps of the surface. This data was plugged into computer simulations to see how shadows change as the Moon moves in its orbit, so that regions in permanent shadow could be identified. The Lunar Reconnaissance Orbiter Camera (LROC) helped by making images of the actual regions of light and shade, which were used to verify the simulation's accuracy. Finally, LOLA measured the depths of polar craters to find areas where the impact could still be seen from Earth.
Since hydrogen is a component of water, maps of lunar hydrogen deposits are useful for finding areas that might hold water. Preliminary hydrogen maps were provided by the spacecraft's Lunar Exploration Neutron Detector (LEND) instrument. Regions that had relatively high amounts of hydrogen were identified as the most promising for the impact.
"Over a year ago, we formally suggested Cabeus to the LCROSS principal investigator," said LEND principal investigator, Igor Mitrofanov of the Institute for Space Research, Moscow. "According to our current data, the regolith within the Cabeus impact crater may have the highest content of water anywhere on the Moon, perhaps up 4.0 percent weight."
"Originally, the LCROSS team was going with a site further north than the Cabeus crater, because it was better for Earth visibility," said Chin. "However, LEND revealed that the area did not have a high hydrogen concentration, but Cabeus did. Also, Diviner showed that Cabeus was one of the coldest sites, and LOLA indicated it was in permanent shadow. So, we were able to inform the decision to aim for Cabeus further south -- while it was a little less visible from Earth, Cabeus was ultimately better for what we were trying to find."
Temperature maps from LRO's Diviner instrument were also crucial to identify where the coldest places were.
David Paige, principal Investigator of the Diviner instrument from the University of California, Los Angeles, used temperature measurements of the lunar south pole obtained by Diviner to model the stability of water ice both at and near the surface.
"The temperatures inside these permanently shadowed craters are even colder than we had expected. Our model results indicate that in these extreme cold conditions, surface deposits of water ice would almost certainly be stable," said Paige, "but perhaps more significantly, these areas are surrounded by much larger permafrost regions where ice could be stable just beneath the surface."
"We conclude that large areas of the lunar south pole are cold enough to trap not only water ice, but other volatile compounds (substances with low boiling points) such as sulfur dioxide, carbon dioxide, formaldehyde, ammonia, methanol, mercury and sodium," Paige added.
UCLA graduate student and Diviner team member, Paul Hayne, was monitoring the data in real-time as it was sent back from Diviner.
"During the fly-by 90 seconds after impact, all seven of Diviner's infrared channels measured an enhanced thermal signal from the crater. The more sensitive of its two solar channels also measured the thermal signal, along with reflected sunlight from the impact plume. Two hours later, the three longest wavelength channels picked up the signal, and after four hours only one channel detected anything above the background temperature."
Scientists were able to learn two things from these measurements: first, they were able to constrain the mass of material that was ejected outwards into space from the impact crater; second, they were able to infer the initial temperature and make estimates about the effects of ice in the soil on the observed cooling behavior.
Another LRO instrument, the Lyman-Alpha Mapping Project (LAMP), used data on the gas cloud to confirm the presence of the molecular hydrogen, carbon monoxide and atomic mercury, along with smaller amounts of calcium and magnesium, all in gaseous form.
"We had hints from Apollo soils and models that the volatiles we see in the impact plume have been long collecting near the Moon’s polar regions," said Randy Gladstone, LAMP acting principal investigator, of Southwest Research Institute (SwRI) in San Antonio, Texas. "Now we have confirmation."
"The detection of mercury in the soil was the biggest surprise, especially that it’s in about the same abundance as the water detected by LCROSS," said Kurt Retherford, LAMP team member, also of SwRI.
"The observations by the suite of LRO and LCROSS instruments demonstrate the moon has a complex environment that experiences intriguing chemical processes," said Richard Vondrak, LRO project scientist at NASA Goddard. "This knowledge can open doors to new areas of research and exploration."
LCROSS launched with LRO aboard an Atlas V rocket from Cape Canaveral, Fla., on June 18, 2009.
The research was funded by NASA's Exploration Systems Missions Directorate at NASA Headquarters in Washington. LRO was built and is managed by NASA's Goddard Space Flight Center in Greenbelt, Md. LCROSS is managed by NASA's Ames Research Center, Moffett Field, Calif. LAMP was developed by the Southwest Research Institute in San Antonio, Texas; LOLA was built by NASA Goddard; LROC was provided by Arizona State University, Tempe; LEND was provided by Institute for Space Research, Moscow; The Diviner instrument was built and is managed by NASA’s Jet Propulsion Laboratory in Pasadena, Calif. UCLA is the home institution of Diviner’s principal investigator.
For more information visit http://www.nasa.gov/mission_pages/LRO/news/lro-lcross-impact.html
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9:16 PM
Gabriella Brianna
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Pyrocumulonimbus is the fire-breathing dragon of clouds.
A cumulonimbus without the "pyre" part is imposing enough -- a massive, anvil-shaped tower of power reaching five miles (8 km) high, hurling thunderbolts, wind and rain.
Add smoke and fire to the mix and you have pyrocumulonimbus, an explosive storm cloud actually created by the smoke and heat from fire, and which can ravage tens of thousands of acres. And in the process, "pyroCb" storms funnel their smoke like a chimney into Earth's stratosphere, with lingering ill effects.
Global Impact
Researchers believe these intense storms may be the source of what previously was believed to have been volcanic particles in the stratosphere. They also suggest pyroCbs happen more often than thought, and say they're responsible for a huge volume of pollutants trapped in the upper atmosphere.
"An individual pyroCb can inject particles into the lower stratosphere as high as 10 miles," says Dr. Glenn K. Yue, an atmospheric scientist at NASA Langley Research Center in Hampton, Va.
Yue is one of eight authors of a paper on pyrocumulonimbus in the September 2010 Bulletin of the American Meteorological Society (BAMS) titled "The Untold Story of Pyrocumulonimbus."
The paper reevaluates previous data to conclude that many stratospheric pollution events erroneously have been attributed to particles from volcanic eruptions.
Three "mystery cloud phenomena" were cited as examples that were actually the result of pyrocumulonimbus storms, including one initially attributed to the 1991 eruption of Mount Pinatubo in the Philippines. The plume thought to have been from Pinatubo was, it turns out, from a pyrocumulonimbus storm in Canada.
One reason for the misinterpretation, Yue said, is that scientists believed nothing less energetic than a volcanic eruption could penetrate Earth's "tropopause" in so short a period of time. The tropopause is the barrier between the lower atmosphere and stratosphere.
"At the time, the thinking was that it was unlikely," said Yue.
SAGE II Data
Yue reevaluated data he'd analyzed years earlier from NASA Langley's SAGE II instrument on the Earth Radiation Budget Satellite. SAGE II was launched in 1984 and turned off in 2005.
"Our paper also shows that pyroCbs happen more often than people realize," Yue added. In 2002, for example, various sensing instruments detected 17 distinct pyrocumulonimbus events in North America alone.
Humans have been responsible for many pyrocumulonimbus storms, says Mike Fromm, lead author on the BAMS paper.
The worst fire in Colorado history was set by a forestry officer "and within 24 hours there was a pyrocumulonimbus storm," says Fromm, a meteorologist at the Naval Research Laboratory in Washington, D.C. Whipped by the storm it had sparked, the 2002 fire swept across 138,000 acres (558.5 sq km) in four counties, drove more than 5,000 from their homes and killed six people.
Whether human actions influence pyrocumulonimbus activity enough to significantly impact the global climate is an open question. Human activity is believed to cause climate warming that leads to more wildfires.
"It's a compelling story line. We don't know enough now to say if there's enough supporting evidence of that," says Fromm.
"There's lots of fairly convincing evidence that under a warming climate, there are forest areas of Siberia and Canada that will be under more heat stress than before. And it's reasonable to think that there will be more fires."
For more informations visit http://www.nasa.gov/topics/earth/features/pyrocb.html
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10:10 PM
Gabriella Brianna
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The most famous of all comets, Comet Halley is noted for producing spectacular displays when it passes near Earth on its 76-year trip around the sun. However, you don't have to wait until 2061 to see a piece of the comet -- you can do it this very week!
Halley's Comet leaves bits of itself behind -- in the form of small conglomerates of dust and ice called meteoroids -- as it moves in its orbit, which the Earth approaches in early May and mid-October. When it does, it collides with these bits of ice and dust, producing a meteor shower as the particles ablate -- or burn up -- many miles above our heads. The May shower is called the Eta Aquarids, as the meteors appear to come from the constellation Aquarius. The October shower has meteors that appear to come from the well-known constellation of Orion the Hunter, hence the name: Orionids.
Orionids move very fast, at a speed of 147,300 miles per hour. At such an enormous speed, the meteors don't last long, burning up very high in the atmosphere. Last year, the NASA allsky cameras at Marshall Space Flight Center in Huntsville, Ala., and in Chickamauga, Ga., recorded 43 definite Orionid meteors. Most of these appeared at an altitude of 68 miles and completely burned up by the time they were 60 miles above the ground, seen in the graph at right.
Even though the peak isn't until October 21, the shower is going on now. The NASA camera systems saw their first Orionid on Oct. 15. Unfortunately, the light from the nearly full moon will wash out the fainter meteors, so expect to see fewer than the 30-per-hour rate you might see under completely dark skies.
The good news is that watching Orionids is easy. Go out into a clear, dark sky after 11 p.m. at night -- your local time -- and lie on a sleeping bag or lawn chair. Look straight up. After a few minutes, your eyes will become dark-adapted, you'll start to see meteors. Any of these that appear to come from Orion will be an Orionid, and therefore represent a piece of Halley's Comet doing its death dive into our atmosphere.
Most folks would consider seeing one or two of these a fair exchange for an hour or so of time. :)
9:12 PM
Gabriella Brianna
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On Saturday, October 16, NASA’s Solar Dynamics Observatory captured this stunning image of one of the most intense, solar flares seen in the past few months. So far there have been no reports of energetic particles from this M-class flare interfering with NASA spacecraft or making their way to Earth.
Fast-growing sunspot 1112 is crackling with solar flares. The three strongest of this 24 hour period: an M3-flare at 1910 UT on Oct. 16th, a C1-flare at 0900 UT and another C1-flare at 1740 UT on Oct. 17th. So far, none of the blasts has hurled a substantial CME toward Earth.
In addition, a vast filament of magnetism is cutting across the sun's southern hemisphere, measuring about 400,000 km. A bright 'hot spot' just north of the filament's midpoint is UV radiation from sunspot 1112. The proximity is no coincidence; the filament appears to be rooted in the sunspot below. If the sunspot flares, it could cause the entire structure to erupt. But so far, none of the flares has destabilized the filament.
9:24 PM
Gabriella Brianna
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Observations with NASA’s Chandra, Swift and Rossi X-ray observatories, Fermi Gamma-ray Space Telescope and ESA’s XMM-Newton have revealed that a slowly rotating neutron star with an ordinary surface magnetic field is giving off bursts of X-rays and gamma rays. This discovery may indicate the presence of an internal magnetic field much more intense than the surface magnetic field, with implications for how the most powerful magnets in the cosmos evolve.
The neutron star, SGR 0418+5729, was discovered on June 5, 2009, when the Fermi Gamma-ray Space Telescope detected bursts of gamma-rays from this object. Follow-up observations four days later with the Rossi X-Ray Timing Explorer (RXTE) showed that, in addition to sporadic X-ray bursts, the neutron star exhibits persistent X-ray emission with regular pulsations that indicate that the star has a rotational period of 9.1 seconds. RXTE was able to monitor this activity for about 100 days. This behavior is similar to a class of neutron stars called magnetars, which have strong to extreme magnetic fields 20 to 1000 times above the average of the galactic radio pulsars.
As neutron stars rotate, the radiation of low frequency electromagnetic waves -- or winds of high-energy particles -- carry energy away from the star, causing the rotation rate of the star to gradually decrease. Careful monitoring of SGR 0418 was possible because Chandra and XMM-Newton were able to measure its pulsation period even though it faded by a factor of 10 after the initial detection. What sets SGR 0418 apart from other magnetars is that careful monitoring over a span of 490 days has revealed no detectable decrease in its rotation rate.
The lack of rotational slowing implies that the radiation of low frequency waves must be weak, and hence the surface magnetic field must be much weaker than normal. But this raises another question: Where does the energy come from to power bursts and the persistent X-ray emission from the source?
The generally accepted answer for magnetars is that the energy to power the X-ray and gamma-ray emission comes from an internal magnetic field that has been twisted and amplified in the turbulent interior of the neutron star. Theoretical studies indicate that if the internal field becomes about ten or more times stronger than the surface field, the decay or untwisting of the field can lead to the production of steady and bursting X-ray emission through the heating of the neutron star crust or the acceleration of particles.
A crucial question is how large an imbalance can be maintained between the surface and interior fields. SGR 0418 represents an important test case. The observations already imply an imbalance of between 50 and 100. If further observations by Chandra push the surface magnetic field limit lower, then theorists may have to dig deeper for an explanation of this enigmatic object.
This discovery is the result of an international teamwork from CSIC-IEEC, INAF, University of Padua, MSSL-UCL, CEA-Saclay, Sabanci University and NASA’s Marshall Space Flight Center in Huntsville, Ala. These results appear in the Oct. 14 issue of Science Express, which provides electronic publication of selected science papers in advance of print.
The Marshall Center manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.
For More Information visit http://www.nasa.gov/mission_pages/chandra/news/10-137.html
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9:35 PM
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NASA's Hubble Space Telescope has captured the first snapshots of a suspected asteroid collision. The images show a bizarre X-shaped object at the head of a comet-like trail of material.
In January, astronomers began using Hubble to track the object for five months. They thought they had witnessed a fresh asteroid collision, but were surprised to learn the collision occurred in early 2009.
"We expected the debris field to expand dramatically, like shrapnel flying from a hand grenade," said astronomer David Jewitt of the University of California in Los Angeles, who is a leader of the Hubble observations. "But what happened was quite the opposite. We found that the object is expanding very, very slowly."
The peculiar object, dubbed P/2010 A2, was found cruising around the asteroid belt, a reservoir of millions of rocky bodies between the orbits of Mars and Jupiter. It is estimated modest-sized asteroids smash into each other about once a year. When the objects collide, they inject dust into interplanetary space. But until now, astronomers have relied on models to make predictions about the frequency of these collisions and the amount of dust produced.
Catching colliding asteroids is difficult because large impacts are rare while small ones, such as the one that produced P/2010 A2, are exceedingly faint. The two asteroids that make up P/2010 A2 were unknown before the collision because they were too faint to be noticed. The collision itself was unobservable because of the asteroids' position in relation to the sun. About 10 or 11 months later, in January 2010, the Lincoln Near-Earth Research (LINEAR) Program Sky Survey spotted the comet-like tail produced by the collision. But only Hubble discerned the X pattern, offering unequivocal evidence that something stranger than a comet outgassing had occurred.
Although the Hubble images give compelling evidence for an asteroid collision, Jewitt says he still does not have enough information to rule out other explanations for the peculiar object. In one such scenario, a small asteroid's rotation increases from solar radiation and loses mass, forming the comet-like tail.
"These observations are important because we need to know where the dust in the solar system comes from, and how much of it comes from colliding asteroids as opposed to 'outgassing' comets," Jewitt said. "We also can apply this knowledge to the dusty debris disks around other stars, because these are thought to be produced by collisions between unseen bodies in the disks. Knowing how the dust was produced will yield clues about those invisible bodies."
The Hubble images, taken from January to May 2010 with the telescope's Wide Field Camera 3, reveal a point-like object about 400 feet wide, with a long, flowing dust tail behind a never-before-seen X pattern. Particle sizes in the tail are estimated to vary from about 1/25th of an inch to an inch in diameter.
The 400-foot-wide object in the Hubble image is the remnant of a slightly larger precursor body. Astronomers think a smaller rock, perhaps 10 to 15 feet wide, slammed into the larger one. The pair probably collided at high speed, about 11,000 mph, which smashed and vaporized the small asteroid and stripped material from the larger one. Jewitt estimates that the violent encounter happened in February or March 2009 and was as powerful as the detonation of a small atomic bomb.
Sunlight radiation then swept the debris behind the remnant asteroid, forming a comet-like tail. The tail contains enough dust to make a ball 65 feet wide, most of it blown out of the bigger body by the impact-caused explosion. The science journal Nature will publish the findings in the Oct. 14 issue.
"Once again, Hubble has revealed unexpected phenomena occurring in our celestial 'back yard," said Eric Smith, Hubble Program scientist at NASA Headquarters in Washington. "Though it's often Hubble's deep observations of the universe or beautiful images of glowing nebulae in our galaxy that make headlines, observations like this of objects in our own solar system remind us how much exploration we still have to do locally."
Astronomers do not have a good explanation for the X shape. The crisscrossed filaments at the head of the tail suggest that the colliding asteroids were not perfectly symmetrical. Material ejected from the impact, therefore, did not make a symmetrical pattern, a bit like the ragged splash made by throwing a rock into a lake. Larger particles in the X disperse very slowly and give this structure its longevity.
Astronomers plan to use Hubble again next year to view the object. Jewitt and his colleagues hope to see how far the dust has been swept back by the sun's radiation and how the mysterious X-shaped structure has evolved.
For more information visit http://www.nasa.gov/mission_pages/hubble/news/asteroid-collision.html
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5:26 AM
Gabriella Brianna
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During a period of universal warming 11 billion years ago, quasars -- the brilliant core of active galaxies -- produced fierce radiation blasts that stunted the growth of some dwarf galaxies for approximately 500 million years.
This important conclusion comes from a team of astronomers that used the new capabilities of NASA's Hubble Space Telescope to probe the invisible, remote universe. The team's results will be published in the October 10 issue of The Astrophysical Journal.
Using Hubble's Cosmic Origins Spectrograph (COS), the astronomers identified this era, from 11.7 to 11.3 billion years ago, when the ultraviolet light emitted by active galaxies stripped electrons off helium atoms. The process, known as ionization, heated the intergalactic helium from 18,000 degrees Fahrenheit to nearly 40,000 degrees. This inhibited the gas from gravitationally collapsing to form new generations of stars in some small galaxies.
Because of its greatly improved sensitivity and lower background "noise" compared to previous spectrographs in space, the COS observations were ground-breaking. The observations allowed scientists to produce more detailed measurements of the intergalactic helium than previously possible.
"These COS results yield new insight into an important phase in the history of our universe," said Hubble Program Scientist Eric Smith at NASA Headquarters in Washington.
Michael Shull of the University of Colorado in Boulder and his team studied the spectrum of ultraviolet light produced by a quasar and found signs of ionized helium. This beacon, like a headlight shining through fog, travels through interspersed clouds of otherwise invisible gas and allows for a core sample of the gas clouds.
The universe went through an initial heat wave more than 13 billion years ago when energy from early massive stars ionized cold interstellar hydrogen from the big bang. This epoch is called reionization, because the hydrogen nuclei originally were in an ionized state shortly after the big bang.
The Hubble team found it would take another two billion years before the universe produced sources of ultraviolet radiation with enough energy to reionize the primordial helium that also was cooked up in the big bang. This radiation didn't come from stars, but rather from super massive black holes. The black holes furiously converted some of the gravitational energy of this mass to powerful ultraviolet radiation that blazed out of these active galaxies.
The helium's reionization occurred at a transitional time in the universe's history when galaxies collided to ignite quasars. After the helium was reionized, intergalactic gas again cooled down and dwarf galaxies could resume normal assembly.
"I imagine quite a few more dwarf galaxies may have formed if helium reionization had not taken place," Shull said.
So far, Shull and his team only have one perspective to measure the helium transition to its ionized state. However, the COS science team plans to use Hubble to look in other directions to determine if helium reionization uniformly took place across the universe.
9:21 PM
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Astronomers using NASA's Spitzer Space Telescope have discovered that a giant star in a remote galaxy ended its life with a dust-shrouded whimper instead of the more typical bang.
Researchers suspect that this odd event -- the first one of its kind ever viewed by astronomers – was more common early in the universe.
It also hints at what we would see if the brightest star system in our Milky Way galaxy exploded, or went supernova.
The discovery is reported in a paper published online in the Astrophysical Journal. The lead author is Christopher Kochanek, a professor of astronomy at Ohio State University, Columbus.
For more information visit http://www.nasa.gov/mission_pages/spitzer/news/spitzer20101012.html
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9:46 PM
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A small asteroid will fly past Earth early Tuesday within the Earth-moon system. The asteroid, 2010 TD54, will have its closest approach to Earth’s surface at an altitude of about 45,000 kilometers (27,960 miles) at 6:50 EDT a.m. (3:50 a.m. PDT). At that time, the asteroid will be over southeastern Asia in the vicinity of Singapore. During its flyby, Asteroid 2010 TD54 has zero probability of impacting Earth. A telescope of the NASA-sponsored Catalina Sky Survey north of Tucson, Arizona discovered 2010 TD54 on Oct. 9 at (12:55 a.m. PDT) during routine monitoring of the skies.
2010 TD54 is estimated to be about 5 to 10 meters (16 to 33 feet) wide. Due to its small size, the asteroid would require a telescope of moderate size to be viewed. A five-meter-sized near-Earth asteroid from the undiscovered population of about 30 million would be expected to pass daily within a lunar distance, and one might strike Earth's atmosphere about every 2 years on average. If an asteroid of the size of 2010 TD54 were to enter Earth’s atmosphere, it would be expected to burn up high in the atmosphere and cause no damage to Earth’s surface.
The distance used on the Near Earth Object page is always the calculated distance from the center of Earth. The distance stated for 2010 TD54 is 52,000 kilometers (32,000 miles). To get the distance it will pass from Earth’s surface you need to subtract the distance from the center to the surface (which varies over the planet), or about one Earth radii. That puts the pass distance at about 45,500 kilometers (28,000 miles) above the planet.
NASA detects, tracks and characterizes asteroids and comets passing close to Earth using both ground- and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them, and plots their orbits to determine if any could be potentially hazardous to our planet.
JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.
For more information visit http://www.nasa.gov/topics/solarsystem/features/asteroid20101011.html
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9:59 PM
Gabriella Brianna
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It's a strange-sounding name for a constellation, coming from the Greco-Roman word for giraffe, or "camel leopard". The October Camelopardalids are a collection of faint stars that have no mythology associated with them -- in fact, they didn't begin to appear on star charts until the 17th century.
Even experienced amateur astronomers are hard-pressed to find the constellation in the night sky. But in early October, it comes to prominence in the minds of meteor scientists as they wrestle with the mystery of this shower of meteors, which appears to radiate from the giraffe's innards.
The October Camelopardalids are not terribly spectacular, with only a handful of bright meteors seen on the night of Oct. 5. It may have been first noticed back in 1902, but definite confirmation had to wait until Oct. 2005, when meteor cameras videotaped 12 meteors belonging to the shower. Moving at a speed of 105,000 miles per hour, Camelopardalids ablate, or burn up, somewhere around 61 miles altitude, according to observations from the NASA allsky meteor cameras on the night of Oct. 5, 2010.
So they aren't spectacular. Their speed is calculated. Their "burn up" altitudes and orbits are known. So what's the mystery?
Camelopardalids have orbits -- see diagram at right -- which indicates that they come from a long period comet, like Halley's Comet. But the Camelopardalids don't come from Halley, nor from any of the other comets that have been discovered.
Hence the mystery: somewhere out there is -- or was -- a comet that passes close to Earth which has eluded detection. These tiny, millimeter size bits of ice leaving pale streaks of light in the heavens are our only clues about a comet of a mile, maybe more, in diameter.
This is why astronomers keep looking at the Camelopardalids meteors. They hope that measuring more orbits may eventually help determine the orbit of the comet, enabling us to finally locate and track this shadowy visitor to Earth's neighborhood.
For more information visit http://www.nasa.gov/topics/solarsystem/features/watchtheskies/camelopardalis.html
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10:31 PM
Gabriella Brianna
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Scientists using data from NASA's Cassini spacecraft have learned that distinctive, colorful bands and splotches embellish the surfaces of Saturn's inner, mid-size moons. The reddish and bluish hues on the icy surfaces of Mimas, Enceladus, Tethys, Dione and Rhea appear to be the aftermath of bombardments large and small.
A paper based on the findings was recently published online in the journal Icarus. In it, scientists describe prominent global patterns that trace the trade routes for material exchange between the moons themselves, an outer ring of Saturn known as the E ring and the planet's magnetic environment. The finding may explain the mysterious Pac-Man thermal pattern on Mimas, found earlier this year by Cassini scientists, said lead author Paul Schenk, who was funded by a Cassini data analysis program grant and is based at the Lunar and Planetary Institute in Houston.
"The beauty of it all is how the satellites behave as a family, recording similar processes and events on their surfaces, each in its own unique way," Schenk said. "I don't think anyone expected that electrons would leave such obvious fingerprints on planetary surfaces, but we see it on several moons, including Mimas, which was once thought to be rather bland."
Schenk and colleagues processed raw images obtained by Cassini's imaging cameras from 2004 to 2009 to produce new, high-resolution global color maps of these five moons. The new maps used camera frames shot through visible-light, ultraviolet and infrared filters which were processed to enhance our views of these moons beyond what could be seen by the human eye.
"The richness of the Cassini data set – visible images, infrared images, ultraviolet images, measurements of the radiation belts – is such that we can finally 'paint a picture' as to how the satellites themselves are 'painted,'" said William B. McKinnon, one of six co-authors on the paper. McKinnon is based at Washington University in St. Louis and was also funded by the Cassini data analysis program.
Icy material sprayed by Enceladus, which makes up the misty E ring, appears to leave a brighter, blue signature. The pattern of bluish material on Enceladus, for example, indicates that the moon is covered by the fallback of its own "breath."
Enceladean spray also appears to splatter the parts of Tethys, Dione and Rhea that run into the spray head-on in their orbits around Saturn. But scientists are still puzzling over why the Enceladean frost on the leading hemisphere of these moons bears a coral-colored, rather than bluish, tint.
On Tethys, Dione and Rhea, darker, rust-colored, reddish hues paint the entire trailing hemisphere, or the side that faces backward in the orbit around Saturn. The reddish hues are thought to be caused by tiny particle strikes from circulating plasma, a gas-like state of matter so hot that atoms split into an ion and an electron, in Saturn's magnetic environment. Tiny, iron-rich "nanoparticles" may also be involved, based on earlier analyses by the Cassini visual and infrared mapping spectrometer team.
Mimas is also touched by the tint of Enceladean spray, but it appears on the trailing side of Mimas. This probably occurs because it orbits inside the path of Enceladus, or closer to Saturn, than Tethys, Dione and Rhea.
In addition, Mimas and Tethys sport a dark, bluish band. The bands match patterns one might expect if the surface were being irradiated by high-energy electrons that drift in a direction opposite to the flow of plasma in the magnetic bubble around Saturn. Scientists are still figuring out exactly what is happening, but the electrons appear to be zapping the Mimas surface in a way that matches the Pac-Man thermal pattern detected by Cassini's composite infrared spectrometer, Schenk said.
Schenk and colleagues also found a unique chain of bluish splotches along the equator of Rhea that re-open the question of whether Rhea ever had a ring around it. The splotches do not seem related to Enceladus, but rather appear where fresh, bluish ice has been exposed on older crater rims. Though Cassini imaging scientists recently reported that they did not see evidence in Cassini images of a ring around Rhea, the authors of this paper suggest the crash of orbiting material, perhaps a ring, to the surface of Rhea in the not-too-distant past could explain the bluish splotches.
"Analyzing the image color ratios is a great way to really enhance the otherwise subtle color variations and make apparent some of the processes at play in the Saturn system," said Amanda Hendrix, Cassini deputy project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The Cassini images highlight the importance and potential effects of so-called 'space weathering' that occurs throughout the solar system – on any surface that isn't protected by a thick atmosphere or magnetic field."
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, 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 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/cassini20101007.html
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9:47 PM
Gabriella Brianna
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After nine years of scanning the sky, the Wilkinson Microwave Anisotropy Probe (WMAP) space mission has concluded its observations of the cosmic microwave background, the oldest light in the universe. The spacecraft has not only given scientists their best look at this remnant glow, but also established the scientific model that describes the history and structure of the universe.
"WMAP has opened a window into the earliest universe that we could scarcely imagine a generation ago," said Gary Hinshaw, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md., who manages the mission. "The team is still busy analyzing the complete nine-year set of data, which the scientific community eagerly awaits."
WMAP was designed to provide a more detailed look at subtle temperature differences in the cosmic microwave background that were first detected in 1992 by NASA's Cosmic Background Explorer (COBE). The WMAP team has answered many longstanding questions about the universe's age and composition. WMAP acquired its final science data on Aug. 20. On Sept. 8, the satellite fired its thrusters, left its working orbit, and entered into a permanent parking orbit around the sun.
"We launched this mission in 2001, accomplished far more than our initial science objectives, and now the time has come for a responsible conclusion to the satellite's operations," said Charles Bennett, WMAP's principal investigator at Johns Hopkins University in Baltimore.
WMAP detects a signal that is the remnant afterglow of the hot young universe, a pattern frozen in place when the cosmos was only 380,000 years old. As the universe expanded over the next 13 billion years, this light lost energy and stretched into increasingly longer wavelengths. Today, it is detectable as microwaves.
WMAP is in the Guinness Book of World Records for "most accurate measure of the age of the universe." The mission established that the cosmos is 13.75 billion years old, with a degree of error of one percent.
WMAP also showed that normal atoms make up only 4.6 percent of today's cosmos, and it verified that most of the universe consists of two entities scientists don't yet understand.
Dark matter, which makes up 23 percent of the universe, is a material that has yet to be detected in the laboratory. Dark energy is a gravitationally repulsive entity which may be a feature of the vacuum itself. WMAP confirmed its existence and determined that it fills 72 percent of the cosmos.
Another important WMAP breakthrough involves a hypothesized cosmic "growth spurt" called inflation. For decades, cosmologists have suggested that the universe went through an extremely rapid growth phase within the first trillionth of a second it existed. WMAP's observations support the notion that inflation did occur, and its detailed measurements now rule out several well-studied inflation scenarios while providing new support for others.
"It never ceases to amaze me that we can make a measurement that can distinguish between what may or may not have happened in the first trillionth of a second of the universe," says Bennett.
WMAP was the first spacecraft to use the gravitational balance point known as Earth-Sun L2 as its observing station. The location is about 930,000 miles or (1.5 million km) away.
"WMAP gave definitive measurements of the fundamental parameters of the universe," said Jaya Bapayee, WMAP program executive at NASA Headquarters in Washington. "Scientists will use this information for years to come in their quest to better understand the universe."
Launched as MAP on June 30, 2001, the spacecraft was later renamed WMAP to honor David T. Wilkinson, a Princeton University cosmologist and a founding team member who died in September 2002.
For more information visit http://www.nasa.gov/topics/universe/features/wmap-complete.html
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9:34 PM
Gabriella Brianna
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Hubble Space Telescope observations of comet 103P/Hartley 2, taken on September 25, are helping in the planning for a November 4 flyby of the comet by NASA's Deep Impact eXtended Investigation (DIXI) spacecraft.
Analysis of the new Hubble data shows that the nucleus has a diameter of approximately 0.93 miles (1.5 km), which is consistent with previous estimates.
The comet is in a highly active state, as it approaches the Sun. The Hubble data show that the coma is remarkably uniform, with no evidence for the types of outgassing jets seen from most "Jupiter Family" comets, of which Hartley 2 is a member.
Jets can be produced when the dust emanates from a few specific icy regions, while most of the surface is covered with relatively inert, meteoritic-like material. In stark contrast, the activity from Hartley 2's nucleus appears to be more uniformly distributed over its entire surface, perhaps indicating a relatively "young" surface that hasn't yet been crusted over.
Hubble's spectrographs - the Cosmic Origins Spectrograph (COS) and the Space Telescope Imaging Spectrograph (STIS) -- are expected to provide unique information about the comet's chemical composition that might not be obtainable any other way, including measurements by DIXI. The Hubble team is specifically searching for emissions from carbon monoxide (CO) and diatomic sulfur (S2). These molecules have been seen in other comets but have not yet been detected in 103P/Hartley 2.
103P/Hartley has an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit in Siding Spring, Australia. The comet will pass within 11 million miles of Earth (about 45 times the distance to the Moon) on October 20. During that time the comet may be visible to the naked eye as a 5th magnitude "fuzzy star" in the constellation Auriga.
For more information visit http://www.nasa.gov/mission_pages/hubble/science/hartley-2.html
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9:36 PM
Gabriella Brianna
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From Earth, the Sun looks like a calm, placid body that does little more than shine brightly while marching across the sky. Images from a bit closer, of course, show it’s an unruly ball of hot gas that can expel long plumes out into space – but even this isn’t the whole story. Surrounding the Sun is a roiling wind of electrons and protons that shows constant turbulence at every size scale: long streaming jets, smaller whirling eddies, and even microscopic movements as charged particles circle in miniature orbits. Through it all, great magnetic waves and electric currents move through, stirring up the particles even more.
This solar wind is some million degrees Celsius, can move as fast as 750 kilometers (466 statute miles) per second, and – so far – defies a complete description by any one theory. It’s hotter than expected, for one, and no one has yet agreed which of several theories offers the best explanation.
Now, the ESA/NASA Cluster mission – four identical spacecraft that fly in a tight formation to provide 3-dimensional snapshots of structures around Earth – has provided new information about how the protons in the solar wind are heated.
“We had a perfect window of 50 minutes,” says NASA scientist Melvyn Goldstein, chief of the Geospace Physics Laboratory at NASA’s Goddard Space Flight Center in Greenbelt, Md. and co-author of the new paper that appeared in Physical Review Letters on September 24. “It was a time when the four Cluster spacecraft were so close together they could watch movements in the solar wind at a scale small enough that it was possible to observe the heating of protons through turbulence directly for the first time."
Scientists know that large turbulence tends to “cascade” down into smaller turbulence -- imagine the sharply defined whitecaps on top of long ocean waves. In ocean waves, the energy from such cascades naturally adds a small amount of heat from friction as the particles shift past each other, thus heating the water slightly. But the fast, charged particles – known as “plasma” -- around the sun don’t experience that kind of friction, yet they heat up in a similar way.
“Unlike the usual fluids of everyday life,” says Fouad Sahraoui, lead author of a new paper on the solar wind and a scientist at the CNRS-Ecole Polytechnique-UPMC in France, “plasmas possess electric and magnetic fields generated by the motions of proton and electrons. This changes much of the intuitive images that we get from observing conventional fluids.”
Somehow the magnetic and electric fields in the plasma must contribute to heating the particles. Decades of research on the solar wind have been able to infer the length and effects of the magnetic waves, but direct observation was not possible before the Cluster mission watched large waves from afar. These start long as long wavelength fluctuations, but lose energy – while getting shorter – over time. Loss of energy in the waves transfer energy to the solar wind particles, heating them up, but the exact method of energy transfer, and the exact nature of the waves doing the heating, has not been completely established.
In addition to trying to find the mechanism that heats the solar wind, there’s another mystery: The magnetic waves transfer heat to the particles at different rates depending on their wavelength. The largest waves lose energy at a continuous rate until they make it down to about 100-kilometer wavelength. They then lose energy even more quickly before they hit around 2-kilometer wavelength and return to more or less the previous rate. To tackle these puzzles, scientists used data from Cluster when it was in the solar wind in a position where it could not be influenced by Earth’s magnetosphere.
For this latest paper, the four Cluster spacecraft provided 50 minutes of data at a time when conditions were just right -- the spacecraft were in a homogeneous area of the solar wind, they were close together, and they formed a perfect tetrahedral shape -- such that the instruments could measure electromagnetic waves in three dimensions at the small scales that affect protons.
The measurements showed that the cascade of turbulence occurs through the action of a special kind of traveling waves – named Alfvén waves after Nobel laureate Hannes Alfvén, who discovered them in 1941.
The surprising thing about the waves that Cluster observed is that they pointed perpendicular to the magnetic field. This is in contrast to previous work from the Helios spacecraft, which in the 1970’s examined magnetic waves closer to the sun. That work found magnetic waves running parallel to the magnetic field, which can send particles moving in tight circular orbits – a process known as cyclotron resonance -- thus giving them a kick in both energy and temperature. The perpendicular waves found here, on the other hand, create electric fields that efficiently transfer energy to particles by, essentially, pushing them to move faster.
Indeed, earlier Cluster work suggested that this process – known as Landau damping – helped heat electrons. But, since much of the change in temperature with distance from the sun is due to changes in the proton temperature, it was crucial to understand how they obtained their energy. Since hot electrons do not heat protons very well at all, this couldn’t be the mechanism.
That Landau damping is what adds energy to both protons and electrons – at least near Earth – also helps explain the odd rate change in wave fluctuations as well. When the wavelengths are about 100 kilometers or a bit shorter, the electric fields of these perpendicular waves heat protons very efficiently. So, at these lengths, the waves transfer energy quickly to the surrounding protons -- offering an explanation why the magnetic waves suddenly begin to lose energy at a faster rate. Waves that are about two kilometers, however, do not interact efficiently with protons because the electric fields oscillate too fast to push them. Instead these shorter waves begin to push and heat electrons efficiently and quickly deplete all the energy in the waves.
“We can see that not all the energy is dissipated by protons,” Sahraoui said. “The remaining energy in the wave continues its journey toward smaller scales, wavelengths of about two kilometers long. At that point, electrons in turn get heated.”
Future NASA missions such as the Magnetospheric Multiscale mission, scheduled for launch in 2014, will be able to probe the movements of the solar wind at even smaller scales.
Cluster recently surpassed a decade of passing in and out of our planet's magnetic field, returning invaluable data to scientists worldwide. Besides studying the solar wind, Cluster’s other observations include studying the composition of the earth’s aurora and its magnetosphere.
For more information visit http://www.nasa.gov/topics/solarsystem/sunearthsystem/main/cluster-turbulence.html
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9:29 PM
Gabriella Brianna
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A major instrument due to fly aboard NASA's James Webb Space Telescope is getting its first taste of space in the test facilities at the Rutherford Appleton Laboratory (RAL) in the United Kingdom. The Mid-InfraRed Instrument (MIRI) has been designed to contribute to areas of investigation as diverse as the first light in the early Universe and the formation of planets around other stars.
"The start of space simulation testing of the MIRI is the last major engineering activity needed to enable its delivery to NASA. It represents the culmination of 8 years of work by the MIRI consortium, and is a major progress milestone for the Webb telescope project," said Matt Greenhouse, NASA Project Scientist for the Webb telescope Integrated Science Instrument Module, at NASA's Goddard Space Flight Center, Greenbelt, Md.
The James Webb Space Telescope represents the next generation of space telescope and, unlike its predecessor Hubble, it will have to journey far from home. Its ultimate destination is L2, a gravitational pivot point located 1.5 million kilometers (930,000 miles) away, on the opposite side of the Earth from the Sun. Here it is cool enough for the MIRI to obtain exquisite measurements that astronomers will use to help decipher the Universe. "At L2 we are at an environmentally stable point where we can be permanently shaded from light from the Sun and Earth. That allows us to reach the very low temperatures - as low as 7K (- 447.1 Fahrenheit) in the case of MIRI – that are necessary to measure in the mid-infrared," says Jose Lorenzo Alvarez, MIRI Instrument Manager for European Space Agency (ESA).
The MIRI provides imaging, coronagraphy and integral field spectroscopy over the 5-28 micron wavelength range. It is being developed as a partnership between Europe and the U.S. The MIRI is one of four instruments flying aboard the Webb telescope. The other instruments include: NIRSpec (a near-infrared spectrograph), NIRCam (a near-infrared camera), and TFI (a tunable filter imager).
One of the jewels in the MIRI's crown is the potential to observe star formation that has been triggered by an interaction between galaxies. This phenomena has been difficult to study with Hubble or ground-based telescopes since the optical and near-infrared light from these newly formed stars is hidden from view by clouds of dust that typically surround newly formed stars This will not be a problem for MIRI, as it is sensitive to longer wavelengths of light in the range 5 to 28 microns, which can penetrate the dust.
However, keeping the MIRI at a colder temperature than on Pluto, for a sustained period of time, was one of the biggest engineering challenges facing those charged with constructing the instrument. "A critical aspect, to achieving the right sensitivity, is to ensure stable operation at 7 Kelvin (- 447.1 Fahrenheit) that will last for the five years of the mission," explains Alvarez.
This past spring, the flight model of the MIRI began to take shape as the key sub-assemblies - the imager, the spectrometer optics, and the input-optics and calibration module - were delivered to RAL for integration. Each of the optical sub-assemblies of the MIRI had at that stage already, separately, undergone exhaustive mechanical and thermal testing to make sure they can not only survive the rigors of a journey to L2, but also remain operational for the life of the mission. At RAL, the sub-assemblies were integrated into the flight model and are now being tested again, as a complete instrument, using a specially designed chamber developed at RAL to reproduce the environment at L2.
For the purposes of these environmental and calibration tests the Webb telescope optics are simulated using the MIRI Telescope Simulator (MTS) that was built in Spain. Following completion of these tests, the MIRI will be shipped to NASA's Goddard Space Flight Center in Greenbelt, Md., U.S. next spring, when the instrument will be integrated with the Webb’s Integrated Science Instrument Module.
When the MIRI eventually reaches its sheltered position, located four times further away from the Earth than the Moon, scientists can begin probing the Universe's secrets, including its earliest days. "We'd like to try and identify very young galaxies, containing some of the first stars that formed in the Universe," says Gillian Wright, European Principal Investigator for MIRI based at the U.K. Astronomy Technology Centre, Edinburgh, U.K.
With the current generation of space telescopes, distinguishing between a galaxy mature enough to have a central black hole and a young galaxy at a high redshift is troublesome, as they appeared similar in the near-infrared. A key to the MIRI's potential success is its ability to see through cosmic dust. When stars form they burn through the elements, creating dust which ends up in the interstellar medium of the galaxy. The re-radiated emission from this dust creates a spectrum markedly different from that of a galaxy with no dust; the emission is expected to be 5-10 times stronger in the mature galaxy. "MIRI provides a diagnostic of whether there has been a previous generation of stars that had gone supernova and created dust. In the first generation of stars there would be no dust or black holes because there hadn't been time to make any," explains Wright.
The astronomers who will use the MIRI and the James Webb Space Telescope are also particularly keen to explore the formation of planets around distant stars, another area where the ability to peer through the dust becomes important. "MIRI is absolutely essential for understanding planet formation because we know that it occurs in regions which are deeply embedded in dust," said Wright. MIRI's beam width of 0.1 arc seconds allows the instrument to image 30-35 Astronomical Units (AU) of a proto-planetary disc.
With most such discs thought to be hundreds of AU across, the MIRI can build up highly resolved mosaics of these planetary nurseries in unprecedented detail. With its spectrometer, the MIRI could even reveal the existence of water and/or hydrocarbons within the debris, paving the way for investigations into the habitability of other planetary systems.
The James Webb Space Telescope is a joint project of NASA, ESA and the Canadian Space Agency.
For more information visit http://www.nasa.gov/topics/technology/features/miri-test.html
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8:57 PM
Gabriella Brianna
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