Cassini's CIRS Reveals Saturn Is on a Cosmic Dimmer Switch

Like a cosmic light bulb on a dimmer switch, Saturn emitted gradually less energy each year from 2005 to 2009, according to observations by NASA’s Cassini spacecraft. But unlike an ordinary bulb, Saturn's southern hemisphere consistently emitted more energy than its northern one. On top of that, energy levels changed with the seasons and differed from the last time a spacecraft visited in the early 1980s. These never-before-seen trends came from an analysis of comprehensive data from the Composite Infrared Spectrometer (CIRS), an instrument built by NASA's Goddard Space Flight Center in Greenbelt, Md., as well as a comparison with earlier data from NASA's Voyager spacecraft. When combined with information about the energy coming to Saturn from the sun, the results could help scientists understand the nature of Saturn's internal heat source.

The findings were reported November 9 in the Journal of Geophysical Research-Planets by Liming Li of Cornell University in Ithaca, N.Y. (now at the University of Houston), and colleagues from several institutions, including Goddard and NASA's Jet Propulsion Laboratory in Pasadena Calif., which manages the Cassini mission. "The Cassini CIRS data are very valuable because they give us a nearly complete picture of Saturn," says Li. "This is the only single data set that provides so much information about this planet, and it's the first time that anybody has been able to study the power emitted by one of the giant planets in such detail."

The planets in our solar system lose energy in the form of heat radiation in wavelengths that are invisible to the human eye. The CIRS instrument picks up wavelengths in the thermal infrared region, which is beyond red light, where the wavelengths correspond to heat emission.

"In planetary science, we tend to think of planets as losing power evenly in all directions and at a steady rate," says Li. "Now we know Saturn is not doing that." (Power is the amount of energy emitted per unit of time.)

Instead, Saturn's flow of outgoing energy was lopsided, with its southern hemisphere giving off about one-sixth more energy than the northern one, Li explains. This effect matched Saturn's seasons: during those five Earth years, it was summer in the southern hemisphere and winter in the northern one. (A season on Saturn lasts about seven Earth years.) Like Earth, Saturn has these seasons because the planet is tilted on its axis, so one hemisphere receives more energy from the sun and experiences summer while the other receives less energy and is shrouded in winter. Saturn’s equinox, when the sun was directly over the equator, occurred in August 2009.

In the study, Saturn's seasons looked Earth-like in another way: in each hemisphere, its effective temperature, which characterizes its thermal emission to space, started to warm up or cool down as a change of season approached. Because Saturn's weather is variable and the atmosphere tends to retain heat (called heat inertia), the temperature changes in complicated ways throughout the atmosphere. "The effective temperature provides us a simple way to track the response of Saturn's atmosphere, as a system, to the seasonal changes," says Li. Cassini's observations in the northern hemisphere revealed that the effective temperature gradually dropped from 2005 to 2008 and then started to warm up again by 2009. In Saturn's southern hemisphere, the effective temperature cooled from 2005 to 2009, as the equinox started to approach.

The emitted energy for each hemisphere rose and fell along with the effective temperature. Even so, during this five-year period, the planet as a whole seemed to be slowly cooling down and emitting less energy.

To find out if similar changes were happening one Saturn year ago, the researchers looked at data collected by Voyager in 1980 and 1981. Like Cassini CIRS, Voyager recorded fluctuations in the energy emitted by the planet and in the effective temperature. But Voyager did not see the imbalance between the southern and northern hemispheres; instead, the two regions were much more consistent with each other.

Why wouldn't Voyager have seen the same summer-versus-winter difference between the two hemispheres? The amount of energy coming from the sun (called solar radiance), which drives weather and atmospheric temperatures, could have fluctuated from one Saturn year to the next. The patterns in Saturn's cloud cover and haze could have, too.

"It's reasonable to think that the changes in Saturn's emitted power are related to cloud cover," says Amy Simon-Miller, who heads the Planetary Systems Laboratory at Goddard and is a co-author on the paper. "As the amount of cloud cover changes, the amount of radiation escaping into space also changes. This might vary during a single season and from one Saturn year to another. But to fully understand what is happening on Saturn, we will need the other half of the picture: the amount of power being absorbed by the planet."

Li is finishing an analysis of the solar energy that came to Saturn, based on data sets collected by two other Cassini instruments, the imaging science subsystem and the visual and infrared mapping spectrometer. He agrees that this information is crucial because Saturn, like its fellow giant planets Jupiter and Neptune, is thought to have its own source of internal energy. (The fourth giant planet, Uranus, does not seem to have an internal source.) By studying the changes in Saturn's outgoing energy along with the changes in incoming solar energy, scientists can learn about the nature of the planet's internal energy source and whether it, too, changes over time.

"The differences between Saturn's northern and southern hemisphere and that fact that Voyager did not see the same asymmetry raise a very important question: does Saturn's internal heat vary with time?" says Li. "The answer will significantly deepen our understanding of the weather, internal structure and evolution of Saturn and the other giant planets."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA Goddard, where the instrument was built.

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NASA Awards Launch Services Contract for Maven Mission

NASA has selected United Launch Services, LLC of Littleton, Colo., to launch the Mars Atmosphere and Volatile Evolution spacecraft known as MAVEN. MAVEN will launch in November 2013 aboard an Atlas V 401 rocket from Complex 41 at Cape Canaveral Air Force Station, Fla.

The total cost value for the MAVEN launch service is approximately $187 million. This estimated cost includes the task ordered launch service for the Atlas plus additional services under other contracts for payload processing; launch vehicle integration; mission unique launch site ground support; and tracking, data and telemetry services.

MAVEN is a Mars orbiter that will greatly enhance our understanding of Mars' climate history by providing a comprehensive picture of the planet's upper atmosphere, ionosphere, solar energy drivers and atmospheric losses.

NASA's Goddard Space Flight Center in Greenbelt, Md., manages the MAVEN project. MAVEN's principal investigator is based at the University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics. The Launch Services Program at NASA's Kennedy Space Center in Florida is responsible for launch vehicle program management of the Atlas V launch services. United Launch Alliance provides the launch services for United Launch Services.

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NASA Test Fires New Rocket Engine For Commercial Space Vehicle

BAY ST. LOUIS, Miss. -- NASA's John C. Stennis Space Center in Mississippi conducted a successful test firing Wednesday of the liquid-fuel AJ26 engine that will power the first stage of Orbital Sciences Corp.'s Taurus II space launch vehicle. Orbital and its engine supplier, Aerojet, test-fired the engine on Stennis' E-1 test stand. The test directly supports NASA's partnerships to enable commercial cargo flights to the International Space Station.

The initial test, the first in a series of three firings, lasted 10 seconds and served as a short-duration readiness firing to verify AJ26 engine start and shutdown sequences, E-1 test stand operations, and ground-test engine controls.

The test was conducted by a joint operations team comprised of Orbital, Aerojet and Stennis engineers, with Stennis employees serving as test conductors. The joint operations team and other NASA engineers will conduct an in-depth data review of all subsystems in preparation for a 50-second hot-fire acceptance test scheduled several weeks from now. A third hot-fire test at Stennis also is planned to verify tuning of engine control valves.

"Congratulations to Orbital and Aerojet for successfully completing another major milestone," said Doug Cooke, associate administrator for the Exploration Systems Mission Directorate at NASA Headquarters in Washington. "This brings us one step closer to realizing NASA's goals for accessing low Earth orbit via commercial spacecraft."

The AJ26 engine is designed to power the Taurus II space vehicle on flights to low Earth orbit. The NASA-Orbital partnership was formed under the agency's Commercial Orbital Transportation Services joint research and development project. The company is under contract with NASA to provide eight cargo missions to the space station through 2015.

"With this first test, Stennis not only demonstrates its versatility and status as the nation's premiere rocket engine test facility, it also opens an exciting new chapter in the nation's space program," said Patrick Scheuermann, Stennis' center director. "We're proud to be partnering with Orbital to enable the wave of the future -- commercial flights to space and eventual resupply of cargo to the International Space Station."

In addition to the Orbital partnership, Stennis also conducts testing on Pratt & Whitney Rocketdyne's RS-68 rocket engine. The AJ26 is the first new engine in years to be tested at Stennis. Operators spent more than two years modifying the E-1 test stand in preparation. Work included construction of a 27-foot-deep flame deflector trench, major structural modifications and new fluid and gas delivery systems.

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Cool Star is a Gem of a Find

NASA's Wide-field Infrared Survey Explorer, or WISE, has eyed its first cool brown dwarf: a tiny, ultra-cold star floating all alone in space.

WISE is scanning the whole sky in infrared light, picking up the glow of not just brown dwarfs but also asteroids, stars and galaxies. It has sent millions of images down to Earth, in which infrared light of different wavelengths is color-coded in the images.

"The brown dwarfs jump out at you like big, fat, green emeralds," said Amy Mainzer, the deputy project scientist of WISE at NASA's Jet Propulsion Laboratory in Pasadena, Calif. Mainzer, who makes jewelry in her spare time, explained that the brown dwarfs appear like green gems in WISE images because the methane in their atmospheres absorbs the infrared light that has been coded blue, and because they are too faint to give off the infrared light that is color-coded red. The only color left is green.

Like Jupiter, brown dwarfs are made up of gas -- a lot of it in the form of methane, hydrogen sulfide, and ammonia. These gases would be deadly to humans at the concentrations found around brown dwarfs. And they wouldn't exactly smell pretty.

"If you could bottle up a gallon of this object's atmosphere and bring it back to Earth, smelling it wouldn't kill you, but it would stink pretty badly -- like rotten eggs with a hint of ammonia," said Mainzer.

Mainzer and other members of the WISE team are already accumulating a quarry of brown dwarf candidates similar to this one. Brown dwarfs have masses somewhere between those of a star and a planet. They start out like stars as collapsing balls of gas, but they lack the mass to fuse atoms together at their core and shine with starlight. As time goes on, these lightweights cool off, until they can only be seen in infrared light. There could be many such objects lurking in the neighborhood of our sun, but astronomers know of only a handful so far. WISE is expected to find hundreds, including the coolest and closest of all.

To scientists, brown dwarfs represent the perfect laboratories for studying planet-like atmospheres.

"They're a great test of our understanding of atmospheric physics of planets, since they don't have solid surfaces, and there's no big, bright sun to get in the way," said co-author Michael Cushing, a postdoctoral fellow at JPL.

WISE's new brown dwarf is named WISEPC J045853.90+643451.9 for its location in the sky. It is estimated to be 18 to 30 light-years away and is one of the coolest brown dwarfs known, with a temperature of about 600 Kelvin, or 620 degrees Fahrenheit. That's downright chilly as far as stars go. The fact that this brown dwarf jumped out of the data so easily and so quickly -- it was spotted 57 days into the survey mission -- indicates that WISE will discover many, many more. The discovery was confirmed by follow-up observations at the University of Virginia's Fan Mountain telescope, the Large Binocular Telescope in southeastern Arizona, and NASA's Infrared Telescope Facility on Mauna Kea, Hawaii. The results are in press at the Astrophysical Journal.

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MAVEN Mission to Investigate How Sun Steals Martian Atmosphere

The Red Planet bleeds. Not blood, but its atmosphere, slowly trickling away to space. The culprit is our sun, which is using its own breath, the solar wind, and its radiation to rob Mars of its air. The crime may have condemned the planet's surface, once apparently promising for life, to a cold and sterile existence.

Features on Mars resembling dry riverbeds, and the discovery of minerals that form in the presence of water, indicate that Mars once had a thicker atmosphere and was warm enough for liquid water to flow on the surface. However, somehow that thick atmosphere got lost in space. It appears Mars has been cold and dry for billions of years, with an atmosphere so thin, any liquid water on the surface quickly boils away while the sun's ultraviolet radiation scours the ground.

Such harsh conditions are the end of the road for known forms of life. Although it's possible that martian life went underground, where liquid water may still exist and radiation can't reach.

The lead suspect for the theft is the sun, and its favorite M.O. may be the solar wind. All planets in our solar system are constantly blasted by the solar wind, a thin stream of electrically charged gas that continuously blows from the sun's surface into space. On Earth, our planet's global magnetic field shields our atmosphere by diverting most of the solar wind around it. The solar wind’s electrically charged particles, ions and electrons, have difficulty crossing magnetic fields.



"Mars can't protect itself from the solar wind because it no longer has a shield, the planet's global magnetic field is dead," said Bruce Jakosky of the University of Colorado, Boulder. Jakosky is the Principal Investigator for NASA's MAVEN mission, which will investigate what is responsible for the loss of the martian atmosphere. NASA selected the MAVEN (Mars Atmosphere and Volatile Evolution Mission) on September 15, 2008.

Mars lost its global magnetic field in its youth billions of years ago. Once its planet-wide magnetic field disappeared, Mars' atmosphere was exposed to the solar wind and most of it could have been gradually stripped away. "Fossil" magnetic fields remaining in ancient surfaces and other local areas on Mars don't provide enough coverage to shield much of the atmosphere from the solar wind

Although the solar wind might be the primary method, like an accomplished burglar, the sun’s emissions can steal the martian atmosphere in many ways. However, most follow a basic M.O., the solar wind and the sun’s ultraviolet radiation turns the uncharged atoms and molecules in Mars' upper atmosphere into electrically charged particles (ions). Once electrically charged, electric fields generated by the solar wind carry them away. The electric field is produced by the motion of the charged, electrically conducting solar wind across the interplanetary, solar-produced magnetic field, the same dynamic generators use to produce electrical power.

An exception to this dominant M.O. are atoms and molecules that have enough speed from solar heating to simply run away, they remain electrically neutral, but become hot enough to escape Mars' gravity. Also, solar extreme ultraviolet radiation can be absorbed by molecules, breaking them into their constituent atoms and giving each atom enough energy that it might be able to escape from the planet.

There are other suspects. Mars has more than 20 ancient craters larger than 600 miles across, scars from giant impacts by asteroids the size of small moons. This bombardment could have blasted large amounts of the martian atmosphere into space. However, huge martian volcanoes that erupted after the impacts, like Olympus Mons, could have replenished the martian atmosphere by venting massive amounts of gas from the planet's interior.

It's possible that the hijacked martian air was an organized crime, with both impacts and the solar wind contributing. Without the protection of its magnetic shield, any replacement martian atmosphere that may have issued from volcanic eruptions eventually would also have been stripped away by the solar wind.

Although the solar wind might be the primary method, like an accomplished burglar, the sun’s emissions can steal the martian atmosphere in many ways. However, most follow a basic M.O., the solar wind and the sun’s ultraviolet radiation turns the uncharged atoms and molecules in Mars' upper atmosphere into electrically charged particles (ions). Once electrically charged, electric fields generated by the solar wind carry them away. The electric field is produced by the motion of the charged, electrically conducting solar wind across the interplanetary, solar-produced magnetic field, the same dynamic generators use to produce electrical power.

An exception to this dominant M.O. are atoms and molecules that have enough speed from solar heating to simply run away, they remain electrically neutral, but become hot enough to escape Mars' gravity. Also, solar extreme ultraviolet radiation can be absorbed by molecules, breaking them into their constituent atoms and giving each atom enough energy that it might be able to escape from the planet.

There are other suspects. Mars has more than 20 ancient craters larger than 600 miles across, scars from giant impacts by asteroids the size of small moons. This bombardment could have blasted large amounts of the martian atmosphere into space. However, huge martian volcanoes that erupted after the impacts, like Olympus Mons, could have replenished the martian atmosphere by venting massive amounts of gas from the planet's interior.

It's possible that the hijacked martian air was an organized crime, with both impacts and the solar wind contributing. Without the protection of its magnetic shield, any replacement martian atmosphere that may have issued from volcanic eruptions eventually would also have been stripped away by the solar wind.

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NASA's Fermi Telescope Finds Giant Structure in our Galaxy

WASHINGTON -- NASA's Fermi Gamma-ray Space Telescope has unveiled a previously unseen structure centered in the Milky Way. The feature spans 50,000 light-years and may be the remnant of an eruption from a supersized black hole at the center of our galaxy.

"What we see are two gamma-ray-emitting bubbles that extend 25,000 light-years north and south of the galactic center," said Doug Finkbeiner, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., who first recognized the feature. "We don't fully understand their nature or origin."

The structure spans more than half of the visible sky, from the constellation Virgo to the constellation Grus, and it may be millions of years old. A paper about the findings has been accepted for publication in The Astrophysical Journal.

Finkbeiner and his team discovered the bubbles by processing publicly available data from Fermi's Large Area Telescope (LAT). The LAT is the most sensitive and highest-resolution gamma-ray detector ever launched. Gamma rays are the highest-energy form of light.


Other astronomers studying gamma rays hadn't detected the bubbles partly because of a fog of gamma rays that appears throughout the sky. The fog happens when particles moving near the speed of light interact with light and interstellar gas in the Milky Way. The LAT team constantly refines models to uncover new gamma-ray sources obscured by this so-called diffuse emission. By using various estimates of the fog, Finkbeiner and his colleagues were able to isolate it from the LAT data and unveil the giant bubbles.

Scientists now are conducting more analyses to better understand how the never-before-seen structure was formed. The bubble emissions are much more energetic than the gamma-ray fog seen elsewhere in the Milky Way. The bubbles also appear to have well-defined edges. The structure's shape and emissions suggest it was formed as a result of a large and relatively rapid energy release - the source of which remains a mystery.

One possibility includes a particle jet from the supermassive black hole at the galactic center. In many other galaxies, astronomers see fast particle jets powered by matter falling toward a central black hole. While there is no evidence the Milky Way's black hole has such a jet today, it may have in the past. The bubbles also may have formed as a result of gas outflows from a burst of star formation, perhaps the one that produced many massive star clusters in the Milky Way's center several million years ago.

"In other galaxies, we see that starbursts can drive enormous gas outflows," said David Spergel, a scientist at Princeton University in New Jersey. "Whatever the energy source behind these huge bubbles may be, it is connected to many deep questions in astrophysics."

Hints of the bubbles appear in earlier spacecraft data. X-ray observations from the German-led Roentgen Satellite suggested subtle evidence for bubble edges close to the galactic center, or in the same orientation as the Milky Way. NASA's Wilkinson Microwave Anisotropy Probe detected an excess of radio signals at the position of the gamma-ray bubbles.

The Fermi LAT team also revealed Tuesday the instrument's best picture of the gamma-ray sky, the result of two years of data collection.

"Fermi scans the entire sky every three hours, and as the mission continues and our exposure deepens, we see the extreme universe in progressively greater detail," said Julie McEnery, Fermi project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

NASA's Fermi is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

"Since its launch in June 2008, Fermi repeatedly has proven itself to be a frontier facility, giving us new insights ranging from the nature of space-time to the first observations of a gamma-ray nova," said Jon Morse, Astrophysics Division director at NASA Headquarters in Washington. “These latest discoveries continue to demonstrate Fermi's outstanding performance.”

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Sunspot 1121 Unleashes X-ray Flare

Active sunspot 1121 has unleashed one of the brightest x-ray solar flares in years, an M5.4-class eruption at 15:36 UT on Nov. 6th.

Radiation from the flare created a wave of ionization in Earth's upper atmosphere that altered the propagation of low-frequency radio waves. There was, however, no bright CME (plasma cloud) hurled in our direction, so the event is unlikely to produce auroras in the nights ahead.

This is the third M-flare in as many days from this increasingly active sunspot. So far none of the eruptions has been squarely Earth-directed, but this could change in the days ahead as the sun's rotation turns the active region toward our planet.

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A-Train Outreach Jazzes Up Science With New Orleans Students

When NASA scientists visited New Orleans to set up the A-Train Symposium, employees at the hotel hosting the event asked if they would please reach out to local students.

So last week, 14 researchers from NASA and university partners fanned out to classrooms in and around the city, engaging students in discussions about our home planet and the role of the A-Train fleet of Earth-observing satellites.

Topics presented in the schools included the ozone layer, how satellite technology affects the world around us, comparing Mars to Earth, weather and meteorology, careers, the scientific method, and how scientists use the A-Train to collect data.

"The reaction from the students and the teachers was tremendous," said Lin Chambers, one of the scientists from NASA Langley Research Center in Hampton, Va. "I think they were very appreciative of NASA being there, because that's not something we usually do at a symposium like this; and New Orleans is a bit out of the way for most of NASA's activities."

The A-Train collects data on the Earth system, including atmosphere, land surface and oceans. The formation includes the satellites Aqua, CloudSat, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), and Aura.

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NASA Mission in Final Day Before Comet Meetup

Mission controllers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., have relayed final instructions to their comet-bound spacecraft today, Nov. 3. The new programming will guide NASA's EPOXI mission through its close approach with comet Hartley 2, scheduled for tomorrow, Nov. 4, at about 7 a.m. PDT (10 a.m. EDT).

"The last 1 million kilometers are always the hardest," said Tim Larson, EPOXI project manager from JPL. "But we've prepared thoroughly for this day and are confident that come tomorrow morning, we'll be getting the kind of data and imagery that will keep our scientists busy for months to come."

Today at 7 a.m. PDT (10 a.m. EDT), NASA's EPOXI mission was about 1,064,900 kilometers (661,700 miles) from Hartley 2 and closing at a rate of 12.3 kilometers (7.6 miles) per second. Tomorrow at the same time, the spacecraft will be at its closest approach distance to the comet -- approximately 700 kilometers (435 miles) away from its nucleus. All the while, the spacecraft's two imagers and one infrared instrument will be acquiring data.

"We are really looking forward to this because the comet has shown so many surprises, both in the data from EPOXI and the data from our many collaborators, over the last several months," said EPOXI principal investigator Mike A'Hearn from the University of Maryland, College Park."

When the EPOXI mission spacecraft is 18 hours and 798 thousand kilometers (496 thousand miles) away, it will lock its instruments on the comet and begin its encounter phase data collection. As the distances between man-made machine and mysterious space dirtball closes, the frequency of image-taking will increase, reaching a crescendo in the minutes surrounding approach. All data collected during encounter phase will be loaded into spacecraft memory for later playback.

If all goes as planned, about 50 minutes before closest approach, the spacecraft's onboard autopilot – AutoNav Mode – is expected to go active. When in AutoNav Mode, the spacecraft receives attitude (pointing) instructions from its computer to help keep the comet's nucleus centered in spacecraft's imagers.

"We're using AutoNav Mode because our mission control is 23 million miles away from the spacecraft at time of encounter," said Larson. "Any command we would send to the spacecraft would take 75 seconds to get there. Not the kind of thing you want to do when you're talking about hurtling past a 2.2 kilometer-wide object [1.36 miles] at 27,500 miles per hour [about 44,256 kilometers per hour]." AutoNav Mode works by having the spacecraft's Medium-Resolution Imager look for the brightest light source in the sky (excluding the sun). It then assumes that the bright light source must be the comet's nucleus and adjusts the spacecraft's attitude accordingly to keep its imagers centered.

"This spacecraft's AutoNav worked great during its prime mission in 2005 at comet Tempel 1," said Larson. "While that comet's shape provided one central light source, new data from Arecibo indicate that comet Hartley 2 is more elongated and could have two unique bright spots on the ends. If that is the case, we expect Auto Nav to make a decision on which of the two is brightest and focus on that spot."

The EPOXI team expects to begin receiving imagery from the spacecraft starting about 30 minutes after closest approach. The first images received will be those that were taken when the spacecraft was 18 hours out from its target. They will depict the comet nucleus as little more than a point of light, with the fuzzy coma surrounding it. A few of the close-approach images should be received on the ground one hour after the event occurs.

"Those early images may not be the 'money shot,' but we on the science team will prize them just as well, as they will help us further understand the nature of comets," said A'Hearn. "And when we first see those images surrounding closest approach, we are looking forward to yet another type of nucleus compared to any we have seen up close thus far."

EPOXI is an extended mission that uses the already "in-flight" Deep Impact spacecraft to explore distinct celestial targets of opportunity. The name EPOXI itself is a combination of the names for the two extended mission components: the extrasolar planet observations, called Extrasolar Planet Observations and Characterization (EPOCh), and the flyby of comet Hartley 2, called the Deep Impact Extended Investigation (DIXI). The spacecraft has retained the name "Deep Impact."

NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology, manages the EPOXI mission for NASA's Science Mission Directorate, Washington. The University of Maryland, College Park, is home to the mission's principal investigator, Michael A'Hearn. Drake Deming of NASA's Goddard Space Flight Center, Greenbelt, Md., is the science lead for the mission's extrasolar planet observations. The spacecraft was built for NASA by Ball Aerospace & Technologies Corp., Boulder, Colo.

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Astronomers Find Weird, Warm Spot on an Exoplanet

PASADENA, Calif. -- Observations from NASA's Spitzer Space Telescope reveal a distant planet with a warm spot in the wrong place.

The gas-giant planet, named upsilon Andromedae b, orbits tightly around its star, with one face perpetually boiling under the star's heat. It belongs to a class of planets termed hot Jupiters, so called for their scorching temperatures and large, gaseous constitutions.

One might think the hottest part of these planets would be directly under the sun-facing side, but previous observations have shown that their hot spots may be shifted slightly away from this point. Astronomers thought that fierce winds might be pushing hot, gaseous material around.

But the new finding may throw this theory into question. Using Spitzer, an infrared observatory, astronomers found that upsilon Andromedae b's hot spot is offset by a whopping 80 degrees. Basically, the hot spot is over to the side of the planet instead of directly under the glare of the sun.

"We really didn't expect to find a hot spot with such a large offset," said Ian Crossfield, lead author of a new paper about the discovery appearing in an upcoming issue of Astrophysical Journal. "It's clear that we understand even less about the atmospheric energetics of hot Jupiters than we thought we did."

The results are part of a growing field of exoplanet atmospheric science, pioneered by Spitzer in 2005, when it became the first telescope to directly detect photons from an exoplanet, or a planet orbiting a star other than our sun. Since then, Spitzer, along with NASA's Hubble Space Telescope, has studied the atmospheres of several hot Jupiters, finding water, methane, carbon dioxide and carbon monoxide.

In the new study, astronomers report observations of upsilon Andromedae b taken across five days in February of 2009. This planet whips around its star every 4.6 days, as measured using the "wobble," or radial velocity technique, with telescopes on the ground. It does not transit, or cross in front of, its star as many other hot Jupiters studied by Spitzer do.

Spitzer measured the total combined light from the star and planet, as the planet orbited around. The telescope can't see the planet directly, but it can detect variations in the total infrared light from the system that arise as the hot side of the planet comes into Earth's field of view. The hottest part of the planet will give off the most infrared light.

One might think the system would appear brightest when the planet was directly behind the star, thus showing its full sun-facing side. Likewise, one might think the system would appear darkest when the planet swings around toward Earth, showing its backside. But the system was the brightest when the planet was to the side of the star, with its side facing Earth. This means that the hottest part of the planet is not under its star. It's sort of like going to the beach at sunset to feel the most heat. The researchers aren't sure how this could be.

They've guessed at some possibilities, including supersonic winds triggering shock waves that heat material up, and star-planet magnetic interactions. But these are just speculation. As more hot Jupiters are examined, astronomers will test new theories.

"This is a very unexpected result," said Michael Werner, the Spitzer project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., who was not a part of the study. "Spitzer is showing us that we are a long way from understanding these alien worlds."

The Spitzer observations were made before it ran out of its liquid coolant in May 2009, officially beginning its warm mission.

Other authors of the study are Brad Hansen of UCLA; Joseph Harrington at the University of Central Florida, Orlando; James Y-K. Cho of Queen Mary, University of London, United Kingdom; Drake Deming of NASA's Goddard Space Flight Center, Greenbelt, Md.; Kristen Menou of Columbia University, New York, N.Y.; and Sara Seager of the Massachusetts Institute of Technology, Boston.

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NASA Work Helps Better Predict World's Smoggiest Days

PASADENA, Calif. – A research team led by NASA's Jet Propulsion Laboratory and the California Institute of Technology (Caltech), both in Pasadena, Calif., has fully characterized a key chemical reaction that affects the formation of pollutants in smoggy air in the world's urban areas. When applied to Los Angeles, the laboratory results suggest that, on the most polluted days and in the most polluted parts of L.A., current models are underestimating ozone levels by 5 to 10 percent.

The results—published this week in the journal Science—are likely to have "a small but significant impact on the predictions of computer models used to assess air quality, regulate emissions and estimate the health impact of air pollution," said Mitchio Okumura, professor of chemical physics at Caltech and one of the principal investigators on the research.

"This work demonstrates how important accurate laboratory measurements are to our understanding of the atmosphere," said JPL senior research scientist Stanley P. Sander, who led the JPL team's effort. "This is the first time this crucial chemical reaction has been studied by two teams using complementary methods that allow its details to be understood."

The key reaction in question in this research is between nitrogen dioxide and the hydroxyl radical. In the presence of sunlight, these two compounds, along with volatile organic compounds, play important roles in the chemical reactions that form ozone, which at ground-level is an air pollutant harmful to plants and animals, including humans.

Until about the last decade, scientists thought these two compounds only combined to form nitric acid, a fairly stable molecule with a long atmospheric life that slows ozone formation. Chemists suspected a second reaction might also occur, creating peroxynitrous acid, a less stable compound that falls apart quickly once created, releasing the hydroxyl radical and nitrogen dioxide to resume ozone creation. But until now they weren't sure how quickly these reactions occur and how much nitric acid they create relative to peroxynitrous acid. The JPL team measured this rate using a high-accuracy, JPL-built, advanced chemical reactor. The Caltech team then determined the ratio of the rates of the two separate processes.

Theoretical calculations by chemistry professor Anne McCoy at Ohio State University, Columbus, contributed to understanding of the not-well-studied peroxynitrous acid molecule.

"This work was the synthesis of two very different and difficult experiments," added lead author and former Caltech graduate student Andrew Mollner with Aerospace Corporation, El Segundo, Calif. "While neither experiment in isolation provided definitive results, by combining the two data sets, the parameters needed for air quality models could be precisely determined."

In the end, the researchers found the loss of hydroxyl radical and nitrogen dioxide is slower than previously thought—although the reactions are fast, fewer of the radicals are ending up as nitric acid than had been supposed, and more of them are ending up as peroxynitrous acid. "This means less of the hydroxyl radical and nitrogen dioxide go away, leading to proportionately more ozone, mostly in polluted areas," Okumura said.

Just how much more? To try to get a handle on how their results might affect predictions of ozone levels, they turned to Robert Harley, professor of environmental engineering at the University of California, Berkeley, and William Carter, a research chemist at the University of California, Riverside—both experts in atmospheric modeling—to look at the ratio's impact on predictions of ozone concentrations in various parts of Los Angeles in the summer of 2010.

The result: "In the most polluted areas of L.A.," said Okumura, "they calculated up to 10 percent more ozone production when they used the new rate for nitric acid formation."

Okumura said this strong effect would only occur during the most polluted times of the year, not all year long. Still, he said, considering the significant health hazards ozone can have—recent research has reported that a 10 part-per-billion increase in ozone concentration may lead to a four percent increase in deaths from respiratory causes—any increase in expected ozone levels will be important to people who regulate emissions and evaluate health risks. The precision of these results reduces the uncertainty in the models—an important step in the ongoing effort to improve the accuracy of models used by policymakers.

Okumura believes this work will cause other scientists to reevaluate recommendations made to modelers on the best parameters to use. For the team, however, the next step is to start looking at a wider range of atmospheric conditions where this reaction may also be important.

Sander agrees. "The present work focused on atmospheric conditions related to urban smog—i.e., relatively warm temperatures and high atmospheric pressure," he said. "But the hydroxyl radical/nitrogen dioxide reaction is important at many other altitudes. Future work by the two groups will focus on the parts of the atmosphere affected by long-range transport of pollution by high-altitude winds [in Earth's middle and upper troposphere] and where ozone depletion from human-produced substances is important [the stratosphere]."

The research was supported by grants from NASA, the California Air Resources Board, and the National Science Foundation, along with NASA and Department of Defense fellowships.

JPL is managed for NASA by the California Institute of Technology in Pasadena.

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Explore Energy with NASA during Earth Science Week

We all know how it feels to be low on energy after a long day. Or how it feels to be full of energy after a good night’s rest or a good meal. Energy is just as important to Earth’s everyday life as it is to ours.

“Exploring Energy” is the theme of this year’s Earth Science Week, Oct. 10-16. The American Geological Institute hosts Earth Science Week annually in cooperation with various sponsors to engage people in Earth science and encourage stewardship of Earth.

NASA develops, deploys and manages an array of satellites that monitor and measure energy as it flows into, through and out of the Earth system. During Earth Science Week, a series of short videos will be posted to NASA’s Earth Science Week website at http://climate.nasa.gov/esw2010. Aimed at educators, the videos will present activities for different grade levels that highlight how NASA explores Earth’s energy, such as the energy that fuels hurricanes.

In addition, NASA has contributed to the following materials included in an educator kit designed to help teachers engage students in Earth science before, during and after this special week:

* NASA Climate and Energy Education Resources – A two-sided color information sheet lists NASA websites and other resources for Earth science news, data and imagery, and education activities and programs.
* Web Ranger Bookmark – An oversized color bookmark contains information about WebRangers, a National Park Service program through which kids can explore national parks, monuments and historic sites. The WebRangers website includes a series of activities on climate change and its potential impact on families, neighborhoods and national parks. This series and the bookmark were developed by the National Park Service, NASA and the U.S. Fish and Wildlife Service.
* Tour of the Electromagnetic Spectrum DVD – A NASA video uses 3-D animations to explain the electromagnetic spectrum and shows examples of how people interact with it on a daily basis. The video is also available online at http://missionscience.nasa.gov/nasascience/ems_full_video.html , and a companion educators guide can be downloaded at [link to be made available in next couple weeks].
* Earth's Energy Budget Lithograph – A two-sided lithograph features a full-page color diagram illustrating the various kinds and amounts of energy that enter and leave the Earth system.
* The GLOBE Earth System Science Poster Learning Activities – An activities guide examines connections among environmental phenomena at the local, regional and global scales. The activities help students understand that the environment is a result of the interplay among many processes that take place on varying scales of time and space.
* Solar Cell Energy Nationwide Learning Activity – A MY NASA DATA lesson for grades 7-12 is featured as the March learning activity in the Earth Science Week 2010-2011 Earth Science Activity Calendar. The activity text provides background information about the sun’s energy, what happens to it upon entering Earth’s atmosphere, and the factors impacting the amount of energy produced by solar panels. Students use NASA data to determine areas of the country that are most likely to produce solar energy.

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Wind Shear Accident Was Catalyst for Technology

On that day 25 years ago the public affairs specialist was a young U.S. Air Force airman heading home on leave to North Carolina, flying out of Dallas Fort Worth International Airport.

"I was looking out my window, sitting at the end of the runway aboard the second airplane lined up to take off," said Creech. "I had a window seat and was looking out the window when I noticed some really, really black thunder clouds at our end of the runway. Then I saw orange, extremely bright orange, light. My brain didn't register what I was seeing."

What Creech saw was Delta Flight 191 as it crashed on landing.

"It was like a slow motion thing. There was the initial fireball, but then as the airplane rolled over, breaking apart and slowing down, the fire caught up with it and enveloped it," added Creech. "It all came to a halt directly even with my window, across the other side of the runway in the grass. As soon as the movement stopped, the rain hit. It was like a wall of rain and the fire quickly became a smoke ball, black and white smoke mixed."

"I remember our pilot coming over the intercom and saying something to the effect -- ladies and gentlemen, there has been a tragedy and I'm sorry, but we can't return to the terminal and let anyone deplane," said Creech. "Of course that was the last thing any of us wanted to hear, because anybody who saw that wasn't wanting to stay on their plane and go flying. I know I didn't."

Tail-mounted camera on NASA's 737 captures approach to thunderstorm in Colo., 1992
Click to enlarge

This photo was taken from a tail-mounted camera on board NASA’s Boeing 737 as it approached a thunderstorm during microburst wind shear research in Colorado in 1992. Credit: NASA
One hundred and thirty four people of the 163 on board the Delta Lockheed L-1011 and one person on the ground died that day, in part because of a powerful thunderstorm microburst-induced wind shear, a rare but potentially deadly downdraft.

Dave Hinton, now the deputy director of the Aeronautics Research Directorate at NASA's Langley Research Center, also remembers that accident vividly. He and a team of researchers studied it for years as part of their efforts to help develop predictive wind shear radar, a technology that is now standard on all airliners.

"That [Dallas] microburst has been modeled extensively," said Hinton. "It was very strong as microbursts go -- at the top of the range and a mile and a half to two miles in diameter. That would be easily detectable with the technologies that are out there today."

The Dallas accident, one of three fatal wind shear events in the 70s and 80s, was the catalyst for the invention of those technologies. Within months a government/industry/academia partnership started attacking the problem of wind shear from all sides.

"It was a tremendously productive cooperation between multiple agencies and companies," said Hinton. "We advanced the state of the art from basic knowledge of a meteorological phenomena to developing well-defined system requirements for on-board sensors and crew procedures."

Hinton was part of the NASA team that took to the skies in search of some of those answers. The team flew on a Langley-based Boeing 737 aircraft, equipped with airborne Doppler radar and forward-looking infrared sensors, and went looking for storms near Denver, Colo., and Orlando, Fla. Crews on the ground, from MIT Lincoln Labs and the National Center for Atmospheric Research (NCAR), staffed ground-based radars to help them find events quickly.

"We flew over a two-year period and penetrated on the order of some 70 microbursts, starting with very weak ones and working up to stronger ones," added Hinton. "We validated the models for the sensors, proving that they do in fact work as we intended."

NASA worked very closely with the Federal Aviation Administration and companies interested in building systems during the seven-year wind shear research program.

"They followed the technology development and as a result provided the credibility and basis for certification," said Hinton. "That meant that within two to three years of our wrapping up the project there were certified systems available. " Those airborne systems, better ground-based radar and improved pilot training have now virtually eliminated U.S. airliner wind shear accidents.

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Chandra: What Lies Beneath? Magnetar Enigma Deepens

CAMBRIDGE, Mass. -- 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.

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NASA Simulates the Sun's Power on Earth to Test Hardware Intended for Space

In the hostile environment of space, satellites could get burned by the ultra-hot sun in front of them and chilled by the frigid cold conditions of space behind them.

Researchers at NASA's Marshall Space Flight Center in Huntsville, Ala., are using their Solar Thermal Test Facility to simulate some of the harshest conditions space has to offer to learn what these extreme temperatures can do to flight hardware close to the sun. They're currently testing Strofio, a unique NASA instrument that will fly aboard an upcoming European Space Agency mission, in this facility to test the thermal balance before the instrument is on its way to Mercury.

The facility looks like it belongs in a galaxy far, far away. A two-story tall curved mirror -- actually is made of 144 separate mirror segments, each hexagonally shaped and about 18 inches in diameter -- forms the backbone of the facility.



About 50 yards away, sitting in a field, lies another mirror tilted at a slight angle. This secondary mirror reflects the sun towards the primary mirror, which captures the energy and then focuses inside a small vacuum chamber mounted in front of the mirror’s focal point.

The giant wall of mirrors works by capturing the light from the sun and redirecting that energy to whatever happens to be sitting in the vacuum chamber. That superheats the instrument, allowing scientists to know how their hardware will behave as it nears the sun. Of course they can't use all 144 mirror segments at once -- that would beam 5000 watts worth of energy onto whatever happens to be inside the vacuum chamber. For the Strofio tests, engineers will only need to partially uncover about 26 mirror segments. They'll reach temperatures hot enough to test their instrument, but not so high that they melt away their hard work.

But that's only half the equation. Thanks to the Southwest Research Institute, the NASA facility has installed a liquid nitrogen shroud on the inside of the vacuum chamber that will flow super-cold liquid nitrogen. That will allow engineers to chill the vacuum chamber to the freezing cold temperatures, just like those in deep space.

In the front, the mirrors expose the instrument to the hotness of the sun. In the back, the nitrogen exposes it to the coldness of a vacuum. Together they accurately mimic the conditions of space, allowing scientists to test how their instrument will perform on its actual mission.

"It really gives you a good opportunity to understand how your instrument will perform in the conditions of deep space," says Dr. Jimmy Lee, mission manager for Strofio. "We're trying to understand on Earth how our tool will perform thousands of miles away in radically different conditions. That’s critical for a mission like ours."

These tests prove vital for equipment like Stofio that are destined to travel close to the sun. Strofio will fly in polar orbit around Mercury where it will determine the chemical composition of Mercury's surface using a technique called mass spectroscopy, providing a powerful new data to study the planet's geological history. It will launch with the ESA's Mercury Planetary Orbiter mission in 2014.

When Strofio reaches its orbit around mercury, the sun will expose it to temperatures over 120 degrees Celsius or 248 Fahrenheit. That's a stretch even for the relatively resilient NASA computers which historically only operate at around 24 degrees Celsius or 75 Fahrenheit. Engineers will have to continuously test Strofio to handle the tough Mercury conditions.

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NASA TV Program Wins Emmy

When Tom Shortridge was growing up in small Laurel, Del., with a population of 3,600, he knew he wanted to work in television. He graduated from a technical high school with a concentration in media broadcasting. There Shortridge helped produce daily school newscasts and a weekly news show that aired on local cable. He went on to major in communications in college with a minor in film and video

But the 25-year-old never guessed some day he would be part of a team that would win a regional Emmy award for a NASA TV educational program geared towards high schools students and hosted by Vince Whitfield. "NASA Launchpad" took home a statuette in the Informational/Instructional category for its episode, "Bernoulli's Principle," at the 52nd Capital Regional Emmy Awards held in Washington, June 5.

"I didn't think we even had a chance to get a nomination for the Emmy, let alone win it," said Shortridge. "I guess I'd had dreams of winning a regional Emmy, but I figured if it happened, it would be years away."

Even more amazing than the Emmy he says is the fact that he produces the show for NASA's Langley Research Center, through his employer the National Institute of Aerospace (NIA) in Hampton, Va. "If you told me when I was in high school that I'd win an Emmy working for NASA, I'd be more surprised by the NASA part," said Shortridge. "I was never that into science or engineering."

He credits the team of educators-in-residence at NIA for helping him and co-producer Scott Bednar make award-winning five to seven minute programs that apply science, technology, engineering and mathematics concepts learned in the classroom, to real world challenges.

"They're able to identify the science content to meet educational standards, which allows me to focus on the video production end of things and making sure the content is presented in a way that people like me, non-science-heads, can not only understand it, but be excited by it," said Shortridge.

Co-producers Bednar and Shortridge also work on other NASA "eClips" informational and educational projects, both web-based and broadcast on NASA TV.

Bednar also majored in electronic media and film with a concentration in TV production. "In college I had to make a decision which path to follow, science or media and working with NASA and NIA has allowed me to merge my passion for both," he said.

Like Shortridge, Bednar is at the beginning of his career. "I just turned 25 last week. The Emmy win will definitely help stave off my quarter-life crisis," said the New York Long Island native. "The Emmy nod, let alone win, was completely unexpected at this point in my career. To be honest, winning an Emmy was never even on my radar."

Also like his co-producer Bednar says the award is really a team award. "We work with such an amazing group of people that credit is truly deserved across the board," he said.

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NASA Invites Students to Study the Sun During Solar Week

Want to build a pinhole camera to look at an eclipse? Or learn more about how gigantic telescopes examine the sun? The place to go on the Web is solarweek.org from October 18-22. Twice a year, Solar Week provides a weeklong series of web-based educational activities for classrooms about our magnetic variable star, the sun, and its interactions with Earth and the solar system.

Each day of Solar Week offers a different set of lessons and games for students ranging from the upper elementary to high school level. The site covers everything from solar radiation to pursuing careers in science. For example, on Monday, after learning details about how the sun is a star just like the other ones in the sky, students can play a game to determine just where the sun lies in the Milky Way. Or on Thursday, they measure how fast a coronal mass ejection races from the sun.

Helping to answer the students’ questions on an online bulletin board will be three scientists from NASA’s Goddard Space Flight Center in Greenbelt, Md. who have been involved almost since the project began in 2000. Throughout the week, Heliophysics researchers Terry Kucera, Dawn Myers, and Holly Gilbert will be among some twenty scientists who will share their excitement about the dynamic star at the center of our solar system. “I think it’s great that the kids get direct interaction with the scientists,” says solar physicist Kucera, who is involved with the Solar and Heliospheric Observatory and the Solar Terrestrial Relations Observatory.

Currently run by UC Berkeley, Solar Week was originated by David Alexander in 2000 in coordination with his public outreach work for the Yohkoh solar observatory. He began Solar Week as a means of reaching out to girls and encouraging them in the sciences – incorporating many female solar scientists as role models. The site incorporates only women scientists, but welcomes students of both sexes. The former Sun-Earth Connection Education Forum at UC Berkeley took over Solar Week in 2003 where it is now managed by Karin Hauck and funded through spring of 2011 by NASA’s Sun-Earth Day. Berkeley has continued the tradition of incorporating student interaction with leading scientists at the forefront of Sun-Earth research. “The part of the website I enjoy most is the interactive message board because it’s dynamic,” says Hauck. “You never know what’s going to pop up. Students can be very creative with their questions, and I always learning something new from the scientists’ answers.”

Since one of the goals of Solar Week is to encourage girls to pursue STEM (science, technology, engineering, and math) careers, the Goddard scientists often have to answer questions about their jobs specifically, such as how often they travel or whether their jobs are impacted by the current economy –- and, of course, hobbies like Gilbert’s tournament pool-playing and Myers’s work as a dance teacher come up as well.

“I’m always so grateful,” says Hauck, “that these incredibly busy scientists are willing, year after year, to take time out of their very busy schedules to answer the students’ questions.”

Solar Week is ideal for students studying the solar system, the stars, or astronomy in general. It's also for kids wondering what it's like being a scientist, and pondering possible career choices. For those who miss this week, the activities remain online all year around, but the scientists won’t be available again to answer questions online until next March

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The Moon Puts on Camo

A new geologic map of the moon's Schrödinger basin paints an instant, camouflage-colored portrait of what a mash-up the moon's surface is after eons of violent events. The geologic record at Schrödinger is still relatively fresh because the basin is only about 3.8 billion years old; this makes it the moon's second-youngest large basin (it's roughly 320 kilometers, or 200 miles, in diameter).

Schrödinger is located near the moon's south pole, a region where pockets of permanent ice are thought to exist. The map will help researchers understand lunar geologic history and identify suitable landing sites for future exploration. Scott Mest, a research scientist with the Planetary Science Institute working at NASA's Goddard Space Flight Center in Greenbelt, Md., and his colleagues created this geologic map -- the most detailed one to date -- by combining topographic data from the Lunar Orbiter Laser Altimeter, a Goddard instrument aboard the 2009 Lunar Reconnaissance Orbiter, with images and spectral data from the earlier Clementine and Lunar Prospector missions

Schrödinger is an example of an intriguing type of basin called a peak-ring. Like the basin rim (brown outer ring), the smaller and more fragmented peak ring (brown inner ring) is a mountainous region of crust that rose up after a huge object, probably measuring 35-40 kilometers, or about 21-25 miles, smacked into the moon here. These areas of raised crust are the oldest rocks in the basin and just about the only material that wasn't melted by the heat from the object's impact. The melted material was spewed in all directions and formed the plains. Patches of plains material can have slightly different textures and albedo (indicated by dark green and kelly green), probably because they cooled at different times. Fractures (black lines) formed in the basin floor as the material cooled

Schrödinger Basin is one of the few areas near the moon's south pole with evidence of recent volcanic activity. This includes lava flows from volcanic activity on the surface (beige areas) as well as explosive eruptions from a vent inside the red area; this vent has brought up dark material that mantles the plains (red area, which is newer than the beige regions). Older volcanic material is spread over a wider range (gray and lime green). More recent cratering by smaller objects has scattered material (yellow areas) near the top of the basin. Next to that (very light green beside yellow) is a region with a knobby texture that suggests loose material that could have come from cratering outside the basin or from a landslide on the basin's rim.

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NASA Mission to Asteroid Gets Help From Hubble

PASADENA, Calif. – NASA's Hubble Space Telescope has captured images of the large asteroid Vesta that will help refine plans for the Dawn spacecraft's rendezvous with Vesta in July 2011.

Scientists have constructed a video from the images that will help improve pointing instructions for Dawn as it is placed in a polar orbit around Vesta. Analyses of Hubble images revealed a pole orientation, or tilt, of approximately four degrees more to the asteroid's east than scientists previously thought.

This means the change of seasons between the southern and northern hemispheres of Vesta may take place about a month later than previously expected while Dawn is orbiting the asteroid. The result is a change in the pattern of sunlight expected to illuminate the asteroid. Dawn needs solar illumination for imaging and some mapping activities.

"While Vesta is the brightest asteroid in the sky, its small size makes it difficult to image from Earth," said Jian-Yang Li, a scientist participating in the Dawn mission from the University of Maryland in College Park. "The new Hubble images give Dawn scientists a better sense of how Vesta is spinning, because our new views are 90 degrees different from our previous images. It's like having a street-level view and adding a view from an airplane overhead."

The recent images were obtained by Hubble's Wide Field Camera 3 in February. The images complemented previous ones of Vesta taken from ground-based telescopes and Hubble's Wide Field and Planetary Camera 2 between 1983 and 2007. Li and his colleagues looked at 216 new images -- and a total of 446 Hubble images overall -- to clarify how Vesta was spinning. The journal Icarus recently published the report online.

"The new results give us food for thought as we make our way toward Vesta," said Christopher Russell, Dawn's principal investigator at the University of California, Los Angeles. "Because our goal is to take pictures of the entire surface and measure the elevation of features over most of the surface to an accuracy of about 33 feet, or the height of a three-story building, we need to pay close attention to the solar illumination. It looks as if Vesta is going to have a late northern spring next year, or at least later than we planned."

Launched in September 2007, Dawn will leave Vesta to encounter the dwarf planet Ceres in 2015. Vesta and Ceres are the most massive objects in the main asteroid belt between Mars and Jupiter. Scientists study these celestial bodies as examples of the building blocks of terrestrial planets like Earth. Dawn is approximately 216 million kilometers (134 million miles) away from Vesta. Next summer, the spacecraft will make its own measurements of Vesta's rotating surface and allow mission managers to pin down its axis of spin.

"Vesta was discovered just over 200 years ago, and we are excited now to be on the threshold of exploring it from orbit," said Bob Mase, Dawn's project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We planned this mission to accommodate our imprecise knowledge of Vesta. Ours is a journey of discovery and, with our ability to adapt, we are looking forward to collecting excellent science data at our target."

The Dawn mission is managed by JPL, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate at the agency's headquarters in Washington. Orbital Sciences Corporation of Dulles, Va., designed and built the spacecraft. Several international space organizations are part of the mission team.

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Cassini Catches Saturn Moons in Paintball Fight

PASADENA, Calif. – 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 new images are available at http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.

"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

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Cluster Helps Disentangle Turbulence in the Solar Wind

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.

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NASA Loosens GRIP On Atlantic Hurricane Season

NASA wrapped up one of its largest hurricane research efforts ever last week after nearly two months of flights that broke new ground in the study of tropical cyclones and delivered data that scientists will now be able to analyze for years to come.

While the 2010 hurricane season has been a rather quiet one for coastal dwellers, the churning meteorology of the Atlantic Ocean and Caribbean Sea seemed to cooperate well with the science goals of Genesis and Rapid Intensification Processes (GRIP) experiment. Those goals were designed to answer some of the most fundamental yet still unanswered questions of hurricane science: What ultimately causes hurricanes to form? Why do some tropical depressions become strong hurricanes, while others dissipate? What causes the rapid strengthening often seen in hurricanes?

Mission scientists wanted to capture data on hurricanes as they formed and intensified. Ideally, the NASA planes – the DC-8, WB-57 and Global Hawk – would also fly over systems that were weakening, or that were expected to form into hurricanes yet did not. When the flights had ended, all those goals had been met.

“It was successful beyond my reasonable expectations. It requires cooperation with the weather, and good luck with the aircraft,” said mission scientist Ed Zipser, of the University of Utah. “It's not so much a logistical challenge as it is a toss of the dice by Mother Nature during our time available. But it takes a good airplane, a skillful crew and good luck with the equipment.”

Flying to Hurricanes

Hurricanes Earl and Karl each became important objects of observation for scientists during GRIP. The DC-8 flew to Earl four times, criss-crossing the storm as it intensified to a category 4 hurricane and then weakened. On the final Earl flight, as the storm was breaking down and losing strength, the Global Hawk made its debut hurricane flight and passed over Earl’s eye in concert with the DC-8, providing valuable comparison measurements for the instruments on-board both aircraft. The WB-57 also flew Earl as well as Karl.

At the outset, scientists hoped that several aspects of GRIP would help gather important data as well as complete a couple of technical accomplishments. First, collaboration with the Air Force, NOAA and the National Science Foundation would allow scientists to observe a single storm system with as many as six aircraft. Second, GRIP featured the debut of NASA’s Global Hawk drone in a hurricane research capacity. The unmanned plane’s 24-hour flight range gave scientists the ability to directly observe a hurricane as it changed over time and distance in a way that conventional planes and satellites have not done before.

Both of these aspects of GRIP were used to great effect during the two major hurricanes observed during the campaign, Earl and Karl. “We’re all very pleased we were able to get the Global Hawk over a hurricane,” said mission scientist Gerry Heymsfield, of NASA’s Goddard Space Flight Center, Greenbelt, Md. “There was a question about that. That’s a major accomplishment both on the science side and the capability side. It really paves the way for future research.”

As the campaign went on, Global Hawk pilots, based remotely at Dryden Flight Research Center, near Palmdale, Calif., grew more comfortable with the drone’s capability at 60,000 feet and over a hurricane. On Sept. 16 and 17, the Global Hawk made a 25-hour flight that included 20 passes over the eye of Karl as it was emerging into a hurricane – precisely the type of formation and storm development that scientists hoped to capture during GRIP.

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'A-Train' Satellites Search for 770 Million Tons of Dust in the Air

Using data from several research satellites, scientists will spend the next three years trying to understand the climate impacts of about 770 million tons of dust carried into the atmosphere every year from the Sahara Desert.

Terra satellite's MODIS image of dust off the west coast of Africa
Click to enlarge

"The people who build climate models make some assumptions about dust and its impact on the climate," said Dr. Sundar Christopher, a professor of atmospheric science at The University of Alabama in Huntsville.

Christopher will use a $500,000 grant from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission, developed and managed by NASA's Langley Research Center in Hampton, Va.

CALIPSO is an Earth observing satellite that provides new insight into the role that clouds and atmospheric aerosols play in air quality, weather and climate. Christopher will use both CALIPSO and Aqua satellite data in his research.

Aqua was the first member launched of a group of satellites termed the Afternoon Constellation, or A-Train, a group of satellites that travel in line, one behind the other, along the same track, as they orbit Earth. Combining the information from several instruments gives a more complete answer to many questions about Earth's atmosphere than would be possible from any single satellite observation taken by itself.

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