As Technicians ready Discovery, Last SRB Assembly Moves to VAB

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The Space Shuttle Program's final solid rocket booster structural assembly -- the right-hand forward -- moved from the Assembly Refurbishment Facility to the Vehicle Assembly Building at Kennedy Space Center on Thursday. The right and left forward assemblies, which are refurbished and processed at KSC, are comprised of three components -- nose cap, frustum and forward skirt. Inside the VAB, the boosters will be stacked and then mated to an external fuel tank for space shuttle Atlantis for what currently is planned as the "launch on need," or potential rescue mission, for Endeavour's STS-134 mission to the International Space Station targeted to launch in 2011.

About three miles away, at Launch Pad 39A, technicians are servicing the solid rocket booster hydraulic power units as the space shuttle Discovery stack is readied for launch. Liftoff remains targeted for Nov. 1 at 4:40 p.m. EDT.

The remnants of Tropical Storm Nicole passed well offshore from Kennedy and aren't affecting operations at the center. Discovery's processing at the pad also was not affected by the storm.

At NASA's Johnson Space Center in Houston, the STS-133 crew will perform a bench review of flight crew equipment.

NASA and NSF-Funded Research Finds First Potentially Habitable Exoplanet

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A team of planet hunters from the University of California (UC) Santa Cruz, and the Carnegie Institution of Washington has announced the discovery of a planet with three times the mass of Earth orbiting a nearby star at a distance that places it squarely in the middle of the star's "habitable zone."
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This discovery was the result of more than a decade of observations using the W. M. Keck Observatory in Hawaii, one of the world's largest optical telescopes. The research, sponsored by NASA and the National Science Foundation, placed the planet in an area where liquid water could exist on the planet's surface. If confirmed, this would be the most Earth-like exoplanet yet discovered and the first strong case for a potentially habitable one.

To astronomers, a "potentially habitable" planet is one that could sustain life, not necessarily one where humans would thrive. Habitability depends on many factors, but having liquid water and an atmosphere are among the most important.

The new findings are based on 11 years of observations of the nearby red dwarf star Gliese 581using the HIRES spectrometer on the Keck I Telescope. The spectrometer allows precise measurements of a star's radial velocity (its motion along the line of sight from Earth), which can reveal the presence of planets. The gravitational tug of an orbiting planet causes periodic changes in the radial velocity of the host star. Multiple planets induce complex wobbles in the star's motion, and astronomers use sophisticated analyses to detect planets and determihttp://www.nasa-spacestation-info.blogspot.com/ne their orbits and masses.

"Keck's long-term observations of the wobble of nearby stars enabled the detection of this multi-planetary system," said Mario R. Perez, Keck program scientist at NASA Headquarters in Washington. "Keck is once again proving itself an amazing tool for scientific research."

Steven Vogt, professor of astronomy and astrophysics at UC Santa Cruz, and Paul Butler of the Carnegie Institution lead the Lick-Carnegie Exoplanet Survey. The team's new findings are reported in a paper published in the Astrophysical Journal and posted online at:

Crew on Track With Treadmill Maintenance

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The three Expedition 25 crew members living and working aboard the orbiting International Space Station spent much of Tuesday conducting maintenance on the treadmill and the potable water system.

Commander Doug Wheelock and Flight Engineer Shannon Walker began their workday removing the privacy enclosure of the Waste Hygiene Compartment as part of an effort to install a T-hose on the Water Processing Apparatus (WPA) of the station’s Water Recovery System (WRS) in the Tranquility node.

Since the treadmill, also known as T2, needed to be removed to access the back of the WRS rack, the crew used this opportunity to perform some maintenance on the treadmill. With assistance from Walker, Wheelock removed the treadmill’s vibration isolation system, rotated the rack and stowed the apparatus in the Harmony module. Afterward, Walker replaced the treadmill’s power avionics unit.

The T2 is one of several exercise devices available to the crew as part of a daily exercise regimen to reduce the loss of bone density and muscle mass that typically occurs during long-duration spaceflight.

With the treadmill safely out of the way, Wheelock initiated a transfer of condensate water to a WPA storage tank. Later, Walker began the installation of the T-hose.
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Working in the Russian segment of the station Flight Engineer Fyodor Yurchikhin set up ham radio equipment to test the feasibility of sending photographs back to Earth through slow scan television video.

Wheelock, Walker and Yurchikhin have been the sole residents of the orbiting complex since the departure of Expedition 24 Commander Alexander Skvortsov and Flight Engineers Tracy Caldwell Dyson and Mikhail Kornienko aboard the Soyuz TMA-18 spacecraft Friday. Their Soyuz landed early Saturday near Arkalyk, Kazakhstan.

At the Baikonur Cosmodrome in Kazakhstan, three additional Expedition 25 flight engineers, NASA astronaut Scott Kelly and Russian cosmonauts Alexander Kaleri and Oleg Skripochka, reviewed rendezvous simulation programs as they await their launch to the station aboard the new Soyuz TMA-01M spacecraft Oct. 7 (Oct. 8, local time).

Goddard Team Obtains the 'Unobtainium' for NASA's Next Space Observatory

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Imagine building a car chassis without a blueprint or even a list of recommended construction materials.
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In a sense, that's precisely what a team of engineers at the NASA Goddard Space Flight Center in Greenbelt, Md., did when they designed a one-of-a-kind structure that is one of 9 key new technology systems of the Integrated Science Instrument Module (ISIM). Just as a chassis supports the engine and other components in a car, the ISIM will hold four highly sensitive instruments, electronics, and other shared instrument systems flying on the James Webb Space Telescope, NASA's next flagship observatory.

From scratch — without past experience to help guide them — the engineers designed the ISIM made of a never-before-manufactured composite material and proved through testing that it could withstand the super-cold temperatures it would encounter when the observatory reached its orbit 1.5-million kilometers (930,000 miles) from Earth. In fact, the ISIM structure survived temperatures that plunged as low as 27 Kelvin (-411 degrees Fahrenheit), colder than the surface of Pluto.
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"It is the first large, bonded composite spacecraft structure to be exposed to such a severe environment," said Jim Pontius, ISIM lead mechanical engineer.

The 26-day test was specifically carried out to test whether the car-sized structure contracted and distorted as predicted when it cooled from room temperature to the frigid — very important since the science instruments must maintain a specific location on the structure to receive light gathered by the telescope's 6.5-meter (21.3-feet) primary mirror. If the structure shrunk or distorted in an unpredictable way due to the cold, the instruments no longer would be in position to gather data about everything from the first luminous glows following the big bang to the formation of star systems capable of supporting life.

"The tolerances are much looser on the Hubble Space Telescope," said Ray Ohl, a Goddard optical engineer who leads ISIM's optical integration and test. "The optical requirements for Webb are even more difficult to meet than those on Hubble."

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Despite repeated cycles of testing, the truss-like assembly designed by Goddard engineers did not crack. The structure shrunk as predicted by only 170 microns — the width of a needle —when it reached 27 Kelvin (-411 degrees Fahrenheit), far exceeding the design requirement of about 500 microns. "We certainly wouldn’t have been able to realign the instruments on orbit if the structure moved too much," said ISIM Structure Project Manager Eric Johnson. "That's why we needed to make sure we had designed the right structure."

Obtaining the Unobtainium

Achieving the milestone was just one of many firsts for the Goddard team. Almost on every level, "we pushed the technology envelope, from the type of material we would use to build ISIM to how we would test it once it was assembled," Pontius added. "The technology challenges are what attracted the people to the program."

One of the first challenges the team tackled after NASA had named Goddard as the lead center to design and develop ISIM was identifying a structural material that would assure the instruments' precise cryogenic alignment and stability, yet survive the extreme gravitational forces experienced during launch.

An exhaustive search in the technical literature for a possible candidate material yielded nothing, leaving the team with only one alternative — developing its own as-yet-to-be manufactured material, which team members jokingly referred to as "unobtainium." Through mathematical modeling, the team discovered that by combining two composite materials, it could create a carbon fiber/cyanate-ester resin system that would be ideal for fabricating the structure's square tubes that measure 75-mm (3-inch) in diameter.

How then would engineers attach these tubes? Again through mathematical modeling, the team found it could bond the pieces together using a combination of nickel-alloy fittings, clips, and specially shaped composite plates joined with a novel adhesive process, smoothly distributing launch loads while holding the instruments in precise locations — a difficult engineering challenge because different materials react differently to changes in temperature.

"We engineered from the small pieces to the big pieces testing along the way to see if the failure theories were correct. We were looking to see where the design could go wrong," Pontius explained. "By incorporating the lessons learned into the final flight structure, we met the requirements and test validated our building-block approach."

Making Cold, Colder

The test inside Goddard's Space Environment Simulator — a three-story thermal-vacuum chamber that simulates the temperature and vacuum conditions found in space — presented its own set of technological hurdles. "We weren't sure we could get the simulator cold enough," said Paul Cleveland, a technical consultant at Goddard involved in the project. For most spacecraft, the simulator's ability to cool down to 100 Kelvin (-279.7 degrees Fahrenheit) is cold enough. Not so for the Webb telescope, which will endure a constant temperature of 39 Kelvin (-389.5 degrees Fahrenheit) when it reaches its deep-space orbit.

The group engineered a giant tuna fish can-like shroud, cooled by helium gas, and inserted it inside the 27-foot diameter chamber. "When you get down to these temperatures, the physics change," Cleveland said. Anything, including wires or small gaps in the chamber, can create an intractable heat source. "It's a totally different arena," he added. "One watt can raise the temperature by 20 degrees Kelvin. We had to meticulously close the gaps."

With the gaps closed and the ISIM safely lowered into the helium shroud, technicians began sucking air from the chamber to create a vacuum. They activated the simulator's nitrogen panels to cool the chamber to 100 Kelvin (-279.7 degrees Fahrenheit) and began injecting helium gas inside the shroud to chill the ISIM to the correct temperature.

To measure ISIM's reaction as it cooled to the sub-freezing temperatures, the team used a technique called photogrammetry, the science of making precise measurements by means of photography. However, using the technique wasn't so cut-and-dried when carried out in a frosty, airless environment, Ohl said. To protect two commercial-grade cameras from extreme frostbite, team members placed the equipment inside specially designed protective canisters and attached the camera assemblies to the ends of a motorized boom.

As the boom made nearly 360-degree sweeps inside the helium shroud, the cameras snapped photos through a gold-coated glass window of reflective, hockey puck-shaped targets bolted onto ISIM's composite tubes. From the photos, the team could precisely determine whether the targets moved, and if so, by how much.

"It passed with flying colors," Pontius said, referring to the negligible shrinkage. "This test was a huge success for us."

With the critical milestone test behind them, team members say their work likely will serve NASA in the future. Many future science missions will also operate in deep space, and therefore would have to be tested under extreme cryogenic conditions. In the meantime, though, the facility will be used to test other Webb telescope systems, including the backplane, the structure to which the Webb telescope’s 18 primary mirror segments are bolted when the observatory is assembled. "We need to characterize its bending at cryogenic temperatures," Ohl said.

Departure Preparations, Science for Crew

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Expedition 24 Commander Alexander Skvortsov and Flight Engineers Tracy Caldwell Dyson and Mikhail Kornienko spent Monday preparing for their departure Thursday from the International Space Station. They packed items to be returned to Earth in their Soyuz TMA-18 spacecraft, reviewed deorbit and landing procedures and checked out their Sokol launch and entry suits.

Once they undock, Expedition 25 will begin its increment with Commander Doug Wheelock and Flight Engineers Shannon Walker and Fyodor Yurchikhin continuing their stay on the station. Skvortsov will ceremonially hand command of the station over to Wheelock Wednesday afternoon.

NASA Astronaut Scott Kelly and Russian Cosmonauts Alexander Kaleri and Oleg Skripochka will join Expedition 25 as flight engineers when they dock in the new Soyuz TMA-01M spacecraft next month.

Walker set up equipment for the Anomalous Long Term Effects in Astronauts' Central Nervous System experiment. Also known as ALTEA, the experiment uses several diagnostic technologies to measure the effect of the exposure of crew members to cosmic radiation. Specifically, ALTEA was set up Monday to measure the effectiveness of materials on the orbital complex designed to shield the crew from this radiation.
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Meanwhile, Kornienko assisted Skvortsov in a session with the Russian Pilot-M experiment. Pilot-M tests piloting skill in simulations on a laptop under stopwatch control and studies the response of cosmonauts to the effects of stress factors in flight.

Yurchikhin worked with the Matryoshka-R experiment. The Russian payload is designed for sophisticated radiation studies and is named after the traditional Russian set of nested dolls.

Wheelock installed a cable that will send power to the Pressurized Multipurpose Module when it is delivered by the STS-133 crew aboard space shuttle Discovery later this year.

Caldwell Dyson set up the U.S. Sound Level Meter and performed an acoustic survey of the station, the data from which she later downloaded to controllers on the ground.

NASA Study Shows Desert Dust Cuts Colorado River Flow

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PASADENA, Calif. – Snowmelt in the Colorado River basin is occurring earlier, reducing runoff and the amount of crucial water available downstream. A new study shows this is due to increased dust caused by human activities in the region during the past 150 years.

The study, led by a NASA scientist and funded by the agency and the National Science Foundation, showed peak spring runoff now comes three weeks earlier than before the region was settled and soils were disturbed. Annual runoff is lower by more than five percent on average compared to pre-settlement levels.
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The findings have major implications for the 27 million people in the seven U.S. states and Mexico who rely on the Colorado River for drinking, agricultural and industrial water. The results were published in this week's Proceedings of the National Academy of Sciences.

The research team was led by Tom Painter, a snow hydrologist at both NASA's Jet Propulsion Laboratory in Pasadena, Calif., and UCLA. The team examined the impact of human-produced dust deposits on mountain snowpacks over the Upper Colorado River basin between 1915 and 2003. Studies of lake sediment cores showed the amount of dust falling in the Rocky Mountains increased by 500 to 600 percent since the mid-to-late 1800s, when grazing and agriculture began to disturb fragile but stable desert soils.

The team used an advanced hydrology model to simulate the balance of water flowing into and out of the river basin under current dusty conditions, and those that existed before soil was disturbed. Hydrologic data gathered from field studies funded by NASA and the National Science Foundation, and measurements of the absorption of sunlight by dust in snow, were combined with the modeling.

More than 80 percent of sunlight falling on fresh snow is typically reflected back into space. In the semi-arid regions of the Colorado Plateau and Great Basin, winds blow desert dust east, triggering dust-on-snow events. When dark dust particles fall on snow, they reduce its ability to reflect sunlight. The snow also absorbs more of the sun's energy. This darker snow cover melts earlier, with some water evaporating into the atmosphere.

Earlier melt seasons expose vegetation sooner, and plants lose water to the atmosphere through the exhalation of vapor. The study shows an annual average of approximately 35-billion cubic feet of water is lost from this exhalation and the overall evaporation that would otherwise feed the Colorado River. This is enough water to supply Los Angeles for 18 months.
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"The compressed mountain runoff period makes water management more difficult than a slower runoff," Painter said. "With the more rapid runoff under dust-accelerated melt, costly errors are more likely to be made when water is released from and captured in Colorado River reservoirs."

Prior to the study, scientists and water managers had a poor understanding of dust-on-snow events. Scientists knew from theory and modeling studies that dust could be changing the way snowfields reflect and absorb sunlight, but no one had measured its full impact on snowmelt rates and runoff over the river basin. The team addressed these uncertainties by making systematic measurements of the sources, frequency and snowmelt impact of dust-on-snow events.

"These researchers brought together their collective expertise to provide a historical context for how the Colorado River and its runoff respond to dust deposition on snow," said Anjuli Bamzai, program director in the National Science Foundation's Division of Atmospheric and Geospace Sciences in Arlington, Va. "The work lays the foundation for future sound water resource management."

Painter believes steps can be taken to reduce the severity of dust-on-snow events in the Colorado River basin. He points to the impact of the Taylor Grazing Act of 1934 for potential guidance on how dust loads can be reduced. The act regulated grazing on public lands to improve rangeland conditions. Lake sediment studies show it decreased the amount of dust falling in the Rocky Mountains by about one quarter.

"Restoration of desert soils could increase the duration of snow cover, simplifying water management, increasing water supplies and reducing the need for additional reservoir storage of water. Peak runoff under cleaner conditions would then come later in summer, when agricultural and other water demands are greater," Painter said.
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"It could also at least partially mitigate the expected regional impacts of climate change, which include reduced Colorado River flows, increased year-to-year variability in its flow rate, and more severe and longer droughts," he added. "Climate models project a seven to 20 percent reduction in Colorado River basin runoff in this century due to climate change."

Other institutions participating in the study include the National Snow and Ice Center in Boulder, Colo.; U.S. Geological Survey Southwest Biological Center in Moab, Utah; University of Washington in Seattle; Center for Snow and Avalanche Studies in Silverton, Colo.; and the University of Colorado-NOAA Western Water Assessment in Boulder.

For more information about NASA and agency programs, visit: http://www.nasa.gov . JPL is managed for NASA by the California Institute of Technology in Pasadena.

NASA's LRO Exposes Moon's Complex, Turbulent Youth

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The moon was bombarded by two distinct populations of asteroids or comets in its youth, and its surface is more complex than previously thought, according to new results from NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft featured in three papers appearing in the Sept. 17 issue of Science.



In the first paper, lead author James Head of Brown University in Providence, R.I., describes results obtained from a detailed global topographic map of the moon created using LRO's Lunar Orbiter Laser Altimeter (LOLA). "Our new LRO LOLA dataset shows that the older highland impactor population can be clearly distinguished from the younger population in the lunar 'maria' -- giant impact basins filled with solidified lava flows," says Head. "The highlands have a greater density of large craters compared to smaller ones, implying that the earlier population of impactors had a proportionally greater number of large fragments than the population that characterized later lunar history."

Meteorite impacts can radically alter the history of a planet. The moon, Mars, and Mercury all bear scars of ancient craters hundreds or even thousands of miles across. If Earth was subjected to this assault as well -- and there's no reason to assume our planet was spared -- these enormous impacts could have disrupted the initial origin of life. Large impacts that occurred later appear to have altered life's evolution. The approximately 110-mile-diameter, partially buried crater at Chicxulub, in the Yucatan Peninsula of Mexico, is from an impact about 65 million years ago that is now widely believed to have led or contributed to the demise of the dinosaurs and many other lifeforms.

Scientists trying to reconstruct the meteorite bombardment history of Earth face difficulty because impact craters are eroded by wind and water, or destroyed by the action of plate tectonics, the gradual movement and recycling of the Earth's crust. However, a rich record of craters is preserved on the moon, because it has only an extremely thin atmosphere – a vacuum better than those typically used for experiments in laboratories on Earth. The moon’s surface has no liquid water and no plate tectonics. The only source of significant erosion is other impacts.

"The moon is thus analogous to a Rosetta stone for understanding the bombardment history of the Earth," said Head. "Like the Rosetta stone, the lunar record can be used to translate the 'hieroglyphics' of the poorly preserved impact record on Earth."

Even so, previous lunar maps had different resolutions, viewing angles, and lighting conditions, which made it hard to consistently identify and count craters. Head and his team used the LOLA instrument on board LRO to build a map that highlights lunar craters with unprecedented clarity. The instrument sends laser pulses to the lunar surface, measures the time that it takes for them to reflect back to the spacecraft, and then with a very precise knowledge of the orbit of the LRO spacecraft, scientists can convert this information to a detailed topographic map of the moon, according to Head.

Objects hitting the moon can be categorized in different “impactor populations,” where each population has its own set of characteristics. Head also used the LOLA maps to determine the time when the impactor population changed. "Using the crater counts from the different impact basins and examining the populations making up the superposed craters, we can look back in time to discover when this transition in impactor populations occurred. The LRO LOLA impact crater database shows that the transition occurred about the time of the Orientale impact basin, about 3.8 billion years ago. The implication is that this change in populations occurred around the same time as the large impact basins stopped forming, and raises the question of whether or not these factors might be related. The answers to these questions have implications for the earliest history of all the planets in the inner solar system, including Earth," says Head.

In the other two Science papers, researchers describe how data from the Diviner Lunar Radiometer Experiment instrument on LRO are showing that the geologic processes that forged the lunar surface were complex as well. The data have revealed previously unseen compositional differences in the crustal highlands, and have confirmed the presence of anomalously silica-rich material in five distinct regions.

Every mineral, and therefore every rock, absorbs and emits energy with a unique spectral signature that can be measured to reveal its identity and formation mechanisms. For the first time ever, LRO's Diviner instrument is providing scientists with global, high-resolution infrared maps of the moon, which are enabling them to make a definitive identification of silicate minerals commonly found within its crust. "Diviner is literally viewing the moon in a whole new light," says Benjamin Greenhagen of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., lead author of one of the Diviner Science papers.

Lunar geology can be roughly broken down into two categories – the anorthositic highlands, rich in calcium and aluminium, and the basaltic maria, which are abundant in iron and magnesium. Both of these crustal rocks are what’s deemed by geologists as 'primitive'; that is, they are the direct result of crystallization from lunar mantle material, the partially molten layer beneath the crust.

Diviner’s observations have confirmed that most lunar terrains have spectral signatures consistent with compositions that fall into these two broad categories. However they have also revealed that the lunar highlands may be less homogenous than previously thought.

In a wide range of terrains, Diviner revealed the presence of lunar soils with compositions more sodium rich than that of the typical anorthosite crust. The widespread nature of these soils reveals that there may have been variations in the chemistry and cooling rate of the magma ocean which formed the early lunar crust, or they could be the result of secondary processing of the early lunar crust.

Most impressively, in several locations around the moon, Diviner has detected the presence of highly silicic minerals such as quartz, potassium-rich, and sodium-rich feldspar - minerals that are only ever found in association with highly evolved lithologies (rocks that have undergone extensive magmatic processing).

The detection of silicic minerals at these locations is a significant finding for scientists, as they occur in areas previously shown to exhibit anomalously high abundances of the element thorium, another proxy for highly evolved lithologies.

"The silicic features we've found on the moon are fundamentally different from the more typical basaltic mare and anorthositic highlands," says Timothy Glotch of Stony Brook University in Stony Brook, N.Y., lead author of the second Diviner Science paper. "The fact that we see this composition in multiple geologic settings suggests that there may have been multiple processes producing these rocks."

One thing not apparent in the data is evidence for pristine lunar mantle material, which previous studies have suggested may be exposed at some places on the lunar surface. Such material, rich in iron and magnesium, would be readily detected by Diviner.

However, even in the South Pole Aitken Basin (SPA), the largest, oldest, and deepest impact crater on the moon -- deep enough to have penetrated through the crust and into the mantle -- there is no evidence of mantle material.

The implications of this are as yet unknown. Perhaps there are no such exposures of mantle material, or maybe they occur in areas too small for Diviner to detect.

However it's likely that if the impact that formed this crater did excavate any mantle material, it has since been mixed with crustal material from later impacts inside and outside SPA. "The new Diviner data will help in selecting the appropriate landing sites for potential future robotic missions to return samples from SPA. We want to use these samples to date the SPA-forming impact and potentially study the lunar mantle, so it's important to use Diviner data to identify areas with minimal mixing," says Greenhagen.

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. LOLA was built by NASA Goddard. David E. Smith from the Massachusetts Institute of Technology and NASA Goddard is the LOLA principal investigator. 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, David Paige.

Discovery Readied for Evening Rollout

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Space shuttle Discovery, joined to its external fuel tank and twin solid rocket boosters, is standing on its mobile launcher platform inside the Vehicle Assembly Building today as technicians get ready to move it to the launch pad this evening. A crawler-transporter has been positioned just outside the VAB's mammoth doors and will move inside later today so the stack can be placed on its sizeable back for the move. The rollout at NASA's Kennedy Space Center in Florida will take about six hours.

Discovery's crew of six astronauts are to perform an integrated entry simulation today at their training base at NASA's Johnson Space Center in Houston.

NASA TV will cover the rollout this evening beginning at 8 p.m. Coverage will continue until it gets dark at Kennedy.

A Growing La NiƱa Chills Out the Pacific

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A Growing La NiƱa Chills Out the Pacific: The tropical Pacific Ocean has transitioned from last winter's El NiƱo conditions to a cool La NiƱa, as shown by new data about sea surface heights, collected by the U.S-French Ocean Surface Topography Mission (OSTM)/Jason-2 oceanography satellite.

This OSTM/Jason-2 image of the Pacific Ocean is based on the average of 10 days of data centered on Sept. 3, 2010. A new image depicts places where the Pacific sea surface height is higher (warmer) than normal as yellow and red, with places where the sea surface is lower (cooler) than normal as blue and purple. Green indicates near-normal conditions. Sea surface height is an indicator of how much of the sun's heat is stored in the upper ocean.

La NiƱa ocean conditions often follow an El NiƱo episode and are essentially the opposite of El NiƱo conditions. During a La NiƱa episode, trade winds are stronger than normal, and the cold water that normally exists along the coast of South America extends to the central equatorial Pacific. La NiƱa episodes change global weather patterns and are associated with less moisture in the air over cooler ocean waters, resulting in less rain along the coasts of North and South America and the equator, and more rain in the far Western Pacific.
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"This La NiƱa has strengthened for the past four months, is strong now and is still building," said Climatologist Bill Patzert of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It will surely impact this coming winter's weather and climate.

"After more than a decade of mostly dry years on the Colorado River watershed and in the American Southwest, and only one normal rain year in the past five years in Southern California, water supplies are dangerously low," Patzert added. "This La NiƱa could deepen the drought in the already parched Southwest and could also worsen conditions that have fueled Southern California's recent deadly wildfires."

NASA will continue to track this change in Pacific climate.

The comings and goings of El NiƱo and La NiƱa are part of a long-term, evolving state of global climate, for which measurements of sea surface height are a key indicator. JPL manages the U.S. portion of the OSTM/Jason-2 mission for NASA's Science Mission Directorate, Washington, D.C.

Five Things About NASA's Mars Curiosity Rover

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Mars Science Laboratory, aka Curiosity, is part of NASA's Mars Exploration Program, a long-term program of robotic exploration of the Red Planet. The mission is scheduled to launch from Cape Canaveral, Fla., in late 2011, and arrive at an intriguing region of Mars in August 2012. The goal of Curiosity, a rolling laboratory, is to assess whether Mars ever had an environment capable of supporting microbial life and conditions favorable for preserving clues about life, if it existed. This will help us better understand whether life could have existed on the Red Planet and, if so, where we might look for it in the future.
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1. How Big Is It?: The Mini Cooper-sized rover is much bigger than its rover predecessors, Spirit, Opportunity and Pathfinder. Curiosity is twice as long (about 2.8 meters, or 9 feet) and four times as heavy as Spirit and Opportunity, which landed in 2004. Pathfinder, about the size of a microwave oven, landed in 1997.

2. Landing--Where and How: In November 2008, possible landing sites were narrowed to four finalists, all linked to ancient wet conditions. NASA will select a site believed to be among the most likely places to hold a geological record of a favorable environment for life. The site must also meet safe-landing criteria. The landing system is similar to a sky crane heavy-lift helicopter. After a parachute slows the rover's descent toward Mars, a rocket-powered backpack will lower the rover on a tether during the final moments before landing. This method allows landing a very large, heavy rover on Mars (instead of the airbag landing systems of previous Mars rovers). Other innovations enable a landing within a smaller target area than previous Mars missions.

3. Toolkit: Curiosity will use 10 science instruments to examine rocks, soil and the atmosphere. A laser will vaporize patches of rock from a distance, and another instrument will search for organic compounds. Other instruments include mast-mounted cameras to study targets from a distance, arm-mounted instruments to study targets they touch, and deck-mounted analytical instruments to determine the composition of rock and soil samples acquired with a powdering drill and a scoop.
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4. Big Wheels: Each of Curiosity's six wheels has an independent drive motor. The two front and two rear wheels also have individual steering motors. This steering allows the rover to make 360-degree turns in-place on the Mars surface. The wheels' diameter is double the wheel diameter on Spirit and Opportunity, which will help Curiosity roll over obstacles up to 75 centimeters (30 inches) high.

5. Rover Power: A nuclear battery will enable Curiosity to operate year-round and farther from the equator than would be possible with only solar power.

DC-8, Global Hawk Complete Coordinated Caribbean Science Flights

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Two NASA environmental research aircraft – a DC-8 flying science laboratory and an unmanned long-endurance Global Hawk – completed coordinated science flights over the AL-92 tropical disturbance southeast of Haiti and the Dominican Republic in the Caribbean Sept. 12, with a follow-up flight by the DC-8 over the same storm system Sept. 13. The flights were part of NASA's six-week Genesis and Rapid Intensification Processes, or GRIP, mission that is studying how and why some tropical storms rapidly intensify into hurricanes while others diminish just as rapidly.
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All nine instruments installed on the DC-8 collected data during its Sunday flight over the storm system, and 21 dropsondes were launched successfully to aid the other instruments in gauging wind profiles and moisture content. After some early difficulties were resolved in flight path coordination with the Global Hawk flying some 20,000 feet above, both aircraft flew two coordinated data-collection passes over the storm at the same time. The passes were also coordinated with a Gulfstream IV operated by the National Oceanic and Atmospheric Administration in the same area.

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The Global Hawk, operated remotely from NASA's Dryden Flight Research Center at Edwards Air Force Base in Southern California, completed a 24.3-hour flight, including seven hours collecting data over the storm system itself, according to payload engineer Dave Fratello at Dryden. The aircraft had departed Edwards at 4:30 a.m. PDT Sunday, and landed at 4:50 a.m. Monday, Sept. 13. Mission scientists are downloading data recorded during the flight from the three specialized meteorological instruments installed on the Global Hawk for the GRIP campaign.

During its follow-up 8.5-hour flight over the storm system on Monday, the DC-8 completed four transects of the center of the system with all nine instruments operating, including the deployment of another 21 dropsondes. The modified jetliner conducted various maneuvers at 32,000 ft. altitude during which the Meteorological Measurement System in the aircraft's nose recorded barometric pressure, temperature, winds and turbulence before the aircraft returning to its deployment base at Fort Lauderdale, Fla.

NASA Data Track Seasonal Pollution Changes Over India

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Data from the Multi-angle Imaging Spectroradiometer (MISR) instrument on NASA's Terra spacecraft have been used in a groundbreaking new university study that examines the concentration, distribution and composition of aerosol pollution over the Indian subcontinent. The study documents the region's very high levels of natural and human-produced pollutants, and uncovered surprising seasonal shifts in the source of the pollution.

Larry Di Girolamo and postdoctoral scientist Sagnik Dey of the University of Illinois, Champaign, used a decade's worth of MISR data to comprehensively analyze aerosol polluhttp://nasa-spacestation-info.blogspot.com/tion over the Indian subcontinent. This densely populated region has poor air quality and lacks on-the-ground pollution monitoring sites. The study was published recently in the Journal of Geophysical Research.

Aerosols — tiny particles suspended in the air — are produced both by natural sources, such as dust and pollen carried on the wind, and by human activities, such as soot and other hydrocarbons released from the burning of fossil fuels. They can affect the environment and human health, causing a range of respiratory problems. Aerosol pollution levels can be measured on the ground, but only the most developed countries have widespread sensor data.

Since standard satellite imaging cannot measure aerosols over land, Di Girolamo and Dey used NASA's MISR, developed and managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. MISR's unique multi-view design allows researchers to differentiate surface variability from the atmosphere so they can observe and quantitatively measure particles in the air. MISR not only measures the amount of aerosols, but can also distinguish between natural and human-produced particles.

The scientists found very high levels of both natural and human-produced aerosol pollutants. The level of atmospheric pollution across most of the country was two to five times higher than World Health Organization guidelines.

But the study also revealed some surprising trends. For example, the researchers noticed consistent seasonal shifts in human-produced versus natural aerosols. Before monsoon season begins, the winds over the Indian subcontinent shift, blowing inland instead of out to sea. These winds carry immense amounts of dust from Africa and the Arabian Peninsula to India, degrading air quality.

"Just before the rains come, the air gets really polluted, and for a long time everyone blamed the dust," Di Girolamo said, "but MISR has shown that not only is there an influx of dust, there's also a massive buildup of man-made pollutants that's hidden within the dust."

During monsoon season, rains wash some of the dust and soot from the air, but other human-produced pollutants continue to build up. After monsoon season, dust transport is reduced, but human-produced pollutant levels skyrocket, as biomass burning and the use of diesel-fueled transportation soar. During winter, seaward-blowing breezes disperse all the pollutants across the subcontinent and out to sea, where they remain until the pre-monsoon winds blow again.

"We desperately needed these observations to help validate our atmospheric models," said Di Girolamo. "We're finding that in a complex area like India, we have a long way to go. But these observations help give us some guidance."

As MISR continues to collect worldwide aerosol data, Di Girolamo says atmospheric scientists will continue to refine models for India and other areas and begin to propose new regulatory measures. The MISR data may also reveal trends in aerosol concentration over time, which can be compared with climate and health data.

Emerging Technologies May Fuel Revolutionary Launcher

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As NASA studies possibilities for the next launcher to the stars, a team of engineers from Kennedy Space Center and several other field centers are looking for a system that turns a host of existing cutting-edge technologies into the next giant leap spaceward.

An early proposal has emerged that calls for a wedge-shaped aircraft with scramjets to be launched horizontally on an electrified track or gas-powered sled. The aircraft would fly up to Mach 10, using the scramjets and wings to lift it to the upper reaches of the atmosphere where a small payload canister or capsule similar to a rocket's second stage would fire off the back of the aircraft and into orbit. The aircraft would come back and land on a runway by the launch site.
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Engineers also contend the system, with its advanced technologies, will benefit the nation's high-tech industry by perfecting technologies that would make more efficient commuter rail systems, better batteries for cars and trucks, and numerous other spinoffs.

It might read as the latest in a series of science fiction articles, but NASA's Stan Starr, branch chief of the Applied Physics Laboratory at Kennedy, points out that nothing in the design calls for brand-new technology to be developed. However, the system counts on a number of existing technologies to be pushed forward.

"All of these are technology components that have already been developed or studied," Starr said. "We're just proposing to mature these technologies to a useful level, well past the level they've already been taken."

For example, electric tracks catapult rollercoaster riders daily at theme parks. But those tracks call for speeds of a relatively modest 60 mph -- enough to thrill riders, but not nearly fast enough to launch something into space. The launcher would need to reach at least 10 times that speed over the course of two miles in Starr's proposal.

The good news is that NASA and universities already have done significant research in the field, including small-scale tracks at NASA's Marshall Space Flight Center in Huntsville, Ala., and at Kennedy. The Navy also has designed a similar catapult system for its aircraft carriers.

As far as the aircraft that would launch on the rail, there already are real-world tests for designers to draw on. The X-43A, or Hyper-X program, and X-51 have shown that scramjets will work and can achieve remarkable speeds.

The group sees NASA's field centers taking on their traditional roles to develop the Advanced Space Launch System. For instance, Langley Research Center in Virginia, Glenn Research Center in Ohio and Ames Research Center in California would work on different elements of the hypersonic aircraft. Dryden Research Center in California, Goddard Space Flight Center in Maryland and Marshall would join Kennedy in developing the launch rail network. Kennedy also would build a launch test bed, potentially in a two-mile long area parallel to the crawlerway leading to Launch Pad 39A.

Because the system calls for a large role in aeronautic advancement along with rocketry, Starr said, "essentially you bring together parts of NASA that aren't usually brought together. I still see Kennedy's core role as a launch and landing facility."

The Advanced Space Launch System is not meant to replace the space shuttle or other program in the near future, but could be adapted to carry astronauts after unmanned missions rack up successes, Starr said.
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The studies and development program could also be used as a basis for a commercial launch program if a company decides to take advantage of the basic research NASA performs along the way. Starr said NASA's fundamental research has long spurred aerospace industry advancement, a trend that the advanced space launch system could continue.

For now, the team proposed a 10-year plan that would start with launching a drone like those the Air Force uses. More advanced models would follow until they are ready to build one that can launch a small satellite into orbit.

A rail launcher study using gas propulsion already is under way, but the team is applying for funding under several areas, including NASA's push for technology innovation, but the engineers know it may not come to pass. The effort is worth it, however, since there is a chance at revolutionizing launches.

Observe the Moon Night' at NASA Goddard’s Visitor Center

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Come to the NASA Goddard Visitor Center on Saturday, September 18, 2010 from 6:30 pm – 10:00 pm for a fun-filled evening celebrating International Observe the Moon Night. Enjoy guest speakers, hands-on activities, laser ranging facility tours*, a public unveiling of Lunar Reconnaissance Orbiter (LRO) images, and of course, Moon observations! Learn why the Moon goes through phases, how it came to look like it does today, and what we’ve discovered as LRO orbits about 30 miles above Moon’s surface. The 2010 International Observe the Moon Night is our opportunity to celebrate the science returned from the Lunar Reconnaissance Orbiter, which was built at NASA Goddard and reached lunar orbit on June 23, 2009.
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* Laser ranging facility tours are open to the first 100 people on a first-come, first-served basis, so arrive at 6:30 pm to ensure your space!

Agenda for the International Observe the Moon Night
(Hands-on activities and moon observations from 6:45 pm – 10:00 pm)

6:30 pm - Welcome and introduction
6:45 pm - Remote presentation by a scientist from the Lunar and Planetary Institute in Houston, TX
6:45 pm - Science On a Sphere shows every 15 minutes, hands-on activities begin
7:00 pm - Laser ranging tours begin and run every half hour, moon observation with amateur astronomers begins
7:30 pm - 8:15 pm - Presentation by local lunar expert
8:30 pm - 9:15 pm - Presentation by local lunar expert
9:15 pm - 10:00 pm – Hands-on activities, moon observation with amateur astronomers

ARTEMIS - The First Earth-Moon Libration Orbiter

In August 1960, NASA launched its first communications satellite, Echo 1. Fifty years later, NASA has achieved another first by placing the ARTEMIS-P1 spacecraft into a unique orbit behind the moon, but not actually orbiting the moon itself. This type of orbit, called an Earth-Moon libration orbit, relies on a precise balancing of the Sun, Earth, and Moon gravity so that a spacecraft can orbit about a virtual location rather than about a planet or moon. The diagrams below show the full ARTEMIS-P1 orbit as it flies in proximity to the moon.
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ARTEMIS-P1 is the first spacecraft to navigate to and perform stationkeeping operations around the Earth-Moon L1 and L2 Lagrangian points. There are five Lagrangian points associated with the Earth-Moon system. The two points nearest the moon are of great interest for lunar exploration. These points are called L1 (located between the Earth and Moon) and L2 (located on the far side of the Moon from Earth), each about 61,300 km (38,100 miles) above the lunar surface. It takes about 14 to 15 days to complete one revolution about either the L1 or L2 point. These distinctive kidney-shaped orbits are dynamically unstable and require weekly monitoring from ground personnel. Orbit corrections to maintain stability are regularly performed using onboard thrusters.

After the ARTEMIS-P1 spacecraft has completed its first four revolutions in the L2 orbit, the ARTEMIS-P2 spacecraft will enter the L1 orbit. The two sister spacecraft will take magnetospheric observations from opposite sides of the moon for three months, then ARTEMIS-P1 will move to the L1 side where they will both remain in orbit for an additional three months. Flying the two spacecraft on opposite sides, then the same side, of the moon provides for collection of new science data in the Sun-Earth-Moon environment. 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. ARTEMIS will also collect unprecedented observations of the space environment behind the dark side of the Moon – the greatest known vacuum in the solar system – by the solar wind. In late March 2011, both spacecraft will be maneuvered into elliptical lunar orbits where they will continue to observe magnetospheric dynamics, solar wind and the space environment over the course of several years.
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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 launched in 2007 and successfully completed their mission earlier this year. The ARTEMIS mission allowed NASA to repurpose two in-orbit spacecraft to extend their useful science mission, saving tens of millions of taxpayer dollars instead of building and launching new spacecraft. Other benefits of this first ever libration orbit mission include the investigation of lunar regions to provide a staging location for both assembly of telescopes or human exploration of planets and asteroids or even to serve as a communication relay location for a future lunar outpost. The navigation and control of the spacecraft will also provide NASA engineers with important information on propellant usage, requirements on ground station resources, and the sensitivity of controlling these unique orbits.

The ARTEMIS mission implementation and operation represents a joint effort between NASA Goddard Space Flight Center in Greenbelt, Md., the Jet Propulsion Laboratory in Calif., and the University of California, Berkeley, Space Sciences Laboratory.

Chandra Finds Evidence for Stellar Cannibalism


Evidence that a star has recently engulfed a companion star or a giant planet has been found using NASA's Chandra X-ray Observatory. The likely existence of such a "cannibal" star provides new insight into how stars and the planets around them may interact as they age.

The star in question, known as BP Piscium (BP Psc), appears to be a more evolved version of our Sun, but with a dusty and gaseous disk surrounding it. A pair of jets several light years long blasting out of the system in opposite directions has also been seen in optical data. While the disk and jets are characteristics of a very young star, several clues -- including the new results from Chandra -- suggest that BP Psc is not what it originally appeared to be.

Instead, astronomers have suggested that BP Psc is an old star in its so-called red giant phase. And, rather than being hallmarks of its youth, the disk and jets are, in fact, remnants of a recent and catastrophic interaction whereby a nearby star or giant planet was consumed by BP Psc.

When stars like the Sun begin to run of nuclear fuel, they expand and shed their outer layers. Our Sun, for example, is expected to swell so that it nearly reaches or possibly engulfs Earth, as it becomes a red giant star.

"It appears that BP Psc represents a star-eat-star Universe, or maybe a star-eat-planet one," said Joel Kastner of the Rochester Institute of Technology, who led the Chandra study. "Either way, it just shows it's not always friendly out there." http://nasa-spacestation-info.blogspot.com/

Several pieces of information have led astronomers to rethink how old BP Psc might be. First, BP Psc is not located near any star-forming cloud, and there are no other known young stars in its immediate vicinity. Secondly, in common with most elderly stars, its atmosphere contains only a small amount of lithium. Thirdly, its surface gravity appears to be too weak for a young star and instead matches up with one of an old red giant.

Chandra adds to this story. Young, low-mass stars are brighter than most other stars in X-rays, and so X-ray observations can be used as a sign of how old a star may be. Chandra does detect X-rays from BP Psc, but at a rate that is too low to be from a young star. Instead, the X-ray emission rate measured for BP Psc is consistent with that of rapidly rotating giant stars.

The spectrum of the X-ray emission -- that is how the amount of X-rays changes with wavelength -- is consistent with flares occurring on the surface of the star, or with interactions between the star and the disk surrounding it. The magnetic activity of the star itself might be generated by a dynamo caused by its rapid rotation. This rapid rotation can be caused by the engulfment process.

"It seems that BP Psc has been energized by its meal," said co-author Rodolfo (Rudy) Montez Jr., also from the Rochester Institute of Technology.

The star's surface is obscured throughout the visible and near-infrared bands, so the Chandra observation represents the first detection at any wavelength of BP Psc itself.

"BP Psc shows us that stars like our Sun may live quietly for billions of years," said co-author David Rodriguez from UCLA, "but when they go, they just might take a star or planet or two with them."

Although any close-in planets were presumably devastated when BP Psc turned into a giant star, a second round of planet formation might be occurring in the surrounding disk, hundreds of millions of years after the first round. A new paper using observations with the Spitzer Space Telescope has reported possible evidence for a giant planet in the disk surrounding BP Psc. This might be a newly formed planet or one that was part of the original planetary system.

"Exactly how stars might engulf other stars or planets is a hot topic in astrophysics today," said Kastner. "We have many important details that we still need to work out, so objects like BP Psc are really exciting to find."

These results appeared in The Astrophysical Journal Letters. Other co-authors on the study were Nicolas Grosso of the University of Strasbourg, Ben Zuckerman from UCLA, Marshall Perrin from the Space Telescope Science Institute, Thierry Forveille of the Grenoble Astrophysics Laboratory in France and James Graham from University of California, Berkeley.

NASA's Marshall Space Flight Center in Huntsville, Ala., 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.

Caught in the Act - Fireballs Light up Jupiter

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Amateur astronomers are first to detect small objects impacting Jupiter

Amateur astronomers working with professional astronomers have spotted two fireballs lighting up Jupiter's atmosphere this summer, marking the first time Earth-based telescopes have captured relatively small objects burning up in the atmosphere of the giant planet. The two fireballs – which produced bright freckles on Jupiter that were visible through backyard telescopes – occurred on June 3, 2010, and August 20, 2010, respectively.


A new paper that includes both pros and amateurs, led by Ricardo Hueso of the Universidad del PaĆ­s Vasco, Bilbao, Spain, appears today in the Astrophysical Journal Letters. In the paper, astronomers estimate the object that caused the June 3 fireball was 8 to 13 meters (30 to 40 feet) in diameter. The object is comparable in size to the asteroid 2010 RF12 that flew by Earth on Wednesday, Sept. 8, and slightly larger than the asteroid 2008 TC3, which burned up above Sudan two years ago.

An impact of this kind on Earth would not be expected to cause damage on the ground. The energy released by the June 3 fireball as it collided with Jupiter's atmosphere was five to 10 times less than the 1908 Tunguska event on Earth, which knocked over tens of millions of trees in a remote part of Russia. Analysis is continuing on the Aug. 20 fireball, but scientists said it was comparable to the June 3 object.

"Jupiter is a big gravitational vacuum cleaner," said Glenn Orton, a co-author on the paper and an astronomer at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It is clear now that relatively small objects, remnants of the formation of the solar system 4.5 billion years ago, still hit Jupiter frequently. Scientists are trying to figure out just how frequently."

Orton and colleagues said this kind of discovery couldn't have been made without amateur astronomers around the world, whose observations of Jupiter provide a near round-the-clock surveillance that would be impossible to do with the long lines of scientists waiting to use the large telescopes. Amateur astronomers, for example, were the first to see the dark spot that appeared on Jupiter in July 2009 as the result of an impact. Professional astronomers are still analyzing that impact.
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Anthony Wesley, an amateur astronomer from Murrumbateman, Australia, who was also the first to take a picture of that dark spot on Jupiter in July 2009, was the first to see the tiny flash on June 3. Amateur astronomers had their telescopes trained on Jupiter that day because they were in the middle of "Jupiter season," when the planet is high in the sky and at its largest size, as seen by backyard telescopes.

Wesley was visiting an amateur astronomer friend about 1,000 kilometers (600 miles) away in Broken Hill, and he set a digital video camera to record images from his telescope at about 60 frames per second. He was watching the live video on a computer screen at his friend's house when he saw a two-and-a-half-second-long flash of light near the limb of the planet.

"It was clear to me straight away it had to be an event on Jupiter," he said. "I'm used to seeing other momentary flashes in the camera from cosmic ray impacts, but this was different. Cosmic ray strikes last only for one frame of video, whereas this flash gradually brightened and then faded over 133 frames."
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Wesley sent a message out on his e-mail list of amateur and professional astronomers, which included Orton. After receiving Wesley's e-mail, Christopher Go of Cebu, Philippines -- who like Wesley, is an amateur astronomer -- checked his own recordings and confirmed that he had seen a flash, too.

Before Wesley's work, scientists didn't know these small-size impacts could be observed, Hueso explained. "The discovery of optical flashes produced by objects of this size helps scientists understand how many of these objects are out there and the role they played in the formation of our solar system," Hueso said.

For three days afterward, Hueso and colleagues looked for signs of the impact in high-resolution images from larger telescopes: NASA's Hubble Space Telescope, Gemini Observatory telescopes in Hawaii and Chile, the Keck telescope in Hawaii, the NASA Infrared Telescope Facility in Hawaii and the European Southern Observatory's Very Large Telescope in Chile. Scientists analyzed the images for thermal disruptions and chemical signatures seen in previous images of Jupiter impacts. In this case, they saw no signs of debris, which allowed them to limit the size of the impactor.
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Based on all these images, and particularly those obtained by Wesley and Go, the astronomers were able to confirm the flash came from some kind of object – probably a small comet or asteroid – that burned up in Jupiter's atmosphere. The impactor likely had a mass of about 500 to 2,000 metric tons (1 million to 4 million pounds), probably about 100,000 times less massive than the object in July 2009.

Calculations also estimated this June 3 impact released about 1 to 4 quadrillion joules (300 million to 1 billion watt-hours) of energy. The second fireball, on Aug. 20, was detected by the amateur Japanese astronomer Masayuki Tachikawa and later confirmed by Aoki Kazuo and Masayuki Ishimaru. It flashed for about 1.5 seconds. The Keck telescope, observing less than a day later, also found no subsequent debris remnants. Scientists are still analyzing this second flash.

Although collisions of this size had never before been detected on Jupiter, some previous models predicted around one collision of this kind a year. Another predicted up to 100 such collisions. Scientists now believe the frequency must be closer to the high end of the scale.

"It is interesting to note that whereas Earth gets smacked by a 10-meter-sized object about every 10 years on average, it looks as though Jupiter gets hit with the same-sized object a few times each month," said Don Yeomans, manager of the Near-Earth Object Program Office at JPL, who was not involved in the paper. "The Jupiter impact rate is still being refined and studies like this one help to do just that."