Monday, February 28, 2011

NASA Dryden Flies New Supersonic Shockwave Probes


NASA’s Dryden Flight Research Center is flight testing two new supersonic shockwave probes to determine their viability as research tools.

The probes were designed by Eagle Aeronautics of Hampton, Va., under a NASA Research Announcement, and manufactured by Triumph Aerospace Systems of Newport News, Va. The probes were first tested in a wind tunnel at NASA's Langley Research Center, also in Hampton.

The new probes are being flown on NASA Dryden's F-15B research test bed aircraft.

Supersonic flight over land is severely restricted in the United States and elsewhere because the sonic booms created by the shock waves propagating from supersonic aircraft are an annoyance to many and can damage private property.

Sonic boom researchers hope the Eagle Aero probes will aid their understanding of supersonic shockwaves. The ultimate goal of NASA's sonic boom research is to find ways to control the shockwaves and lessen the noise, so that it may be possible for supersonic flight to become more routine.

"Using these probes can be a real benefit in understanding and modeling the generation of shock waves and their associated sonic booms," said Dryden research engineer Dan Banks. "They could allow us to accurately define the near-instantaneous flight conditions of the aircraft being probed, while defining that airplane's flow field. At the same time, the probes provide flight condition data on the host aircraft," Banks said.

The primary objective of the flight series is to determine the feasibility of using the Eagle probes for air-to-air shockwave probing. Additional objectives include determining the durability and robustness of the probes in flight, their sensitivity to flight conditions, and the accuracy of the software.

During the initial flight test phase, the probes are attached to an adapter that hangs on the aircraft's centerline instrumented pylon, or CLIP. A large splitter plate separates the CLIP from the F-15B. This helps protect to the aircraft in the unlikely event of flutter, or damaging vibration, that might cause the probes to break off the CLIP.

The two probes are mounted beside each other on the CLIP, one wedge-shaped and the other is conical. Both are designed to make very accurate measurements of supersonic airflow, improving the quality of the shockwave data engineers can glean.

If the probe combo proves robust in this series of tests, researchers could develop a follow-on series with the probes attached one at a time to the F-15B's nose so each has access to the clean airstream in front of the aircraft. Mounting such devices on the aircraft’s nose is the normal and preferred placement, which allows them access to the clean airstream ahead of the carrier aircraft.

Later test flights could include a second supersonic aircraft flying ahead of the probe-carrying F-15 to generate shockwaves for an early look at the probes’ shockwave-sensing capabilities.

Past supersonic shockwave probing efforts, such as the Lancets project flown at Dryden in 2008-2009, used a standard probe. The more streamlined Eagle Aero probes contain accurate high-response transducers that help to eliminate any lag or other errors as they measure upstream and downstream airflow conditions and can measure flow angles.

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Sunday, February 27, 2011

Tracking Maps for NanoSail-D Over the U.S.


NanoSail-D will next be observable with the naked eye from the continental United States, approximately Friday, Feb. 25 through Monday, Mar. 7. NanoSail-D unfurled the first ever 100-square-foot solar sail in low-Earth orbit on Jan. 20 and has been seen and imaged by individuals in several countries around the world. NASA has partnered with to encourage observations of NanoSail-D. is offering cash prizes for the best images of this historic, pioneering spacecraft in the amounts of $500 (grand prize), $300 (first prize) and $100 (second prize). World-wide observers have already been successful in capturing images of NanoSail-D as it darts across the sky with a digital camera.

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Thursday, February 24, 2011

We Are 'Go' for Exploration


A NASA astronaut, a Mars rover "driver" and a space suit designer joined more than 1,000 middle school students in Long Beach, Calif., to discuss careers in space exploration. The event was held in conjunction with the NASA Project Management Challenge 2011, which brings together NASA scientists and engineers from across the nation. Local area high school students will attend a similar event for the Challenge's second day.

"We want to introduce kids to the diversity of careers that are involved in aeronautics and engineering," said Jim Stoffan, NASA Deputy Associate Administrator for Education. "These students may be some of our future engineers and scientists so we want to introduce them to science and engineering, and hopefully inspire them."

Heather Paul, a project engineer at Johnson Space Center in Houston, TX, pulled open a suitcase full of space suit accessories and asked students if space is really hot or really cold for an astronaut. (The answer: It's hot and cold.) Paul, who is working on life support designs for the next generation of space suits, shared with students that the scientific process they study in school is the foundation for how she tests ideas and plans future designs.

Engineer Ashley Stroupe from NASA's Jet Propulsion Laboratory in Pasadena, Calif., invited students on stage to temporarily simulate Mars rocks. Once they were lying on the ground, a rover model gently crept over them to demonstrate its flexibility. When Stroupe told students that women made up a lot of the team that worked on the Mars Exploration Rovers, the students let up a cheer.

And they kept cheering when former NASA Astronaut Ken Bowersox took the stage and told them what it is like to live in space. He explained how studying things in space offers scientists new understandings. He also told students how his stay on the International Space Station, along with another NASA astronaut and a Russian cosmonaut, illustrates how space exploration can build international teamwork.

"This is an opportunity to mirror the Project Management Challenge, whose theme this year is 'Explore and Inspire,'" explained Shelley Canright, NASA Manager of Elementary, Secondary and eEducation. "For these middle and high school students, we want them to see how our scientists and engineers explore space and continue to be inspired by it. We hope these students will also be inspired!"

The topic of exploration seemed to resonate with students. "They've been looking forward to this field trip and are really intrigued by the idea of space," said Jessica McDaniel, sixth grade math and science teacher at the Doris-Topsy Elvord Academy, a charter school in Long Beach. "It's amazing for them to think 'I'm here on Earth. There's so much more out there.' It's a thrill for them."

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Wednesday, February 23, 2011

Leonardo: Frequently Visited ISS Soon to Be Home


The new Permanent Multipurpose Module (PMM) Leonardo should know its way around the International Space Station by now. This flight marks its eighth and final visit to the orbiting laboratory, its new home.

Leonardo was one of three Multipurpose Logistics Modules built by the Italian Space Agency under contract. It was delivered to Kennedy Space Center in 1998.

Its first spaceflight was on Discovery’s STS-102 mission launched March 8, 2001. Leonardo brought six systems racks to the station: two robotic workstation racks for the station's robotic arm and its four cameras, two DC-to-DC converter units which convert electrical power from the station's solar arrays to a form usable by station systems and experiments, the U.S. lab Avionic 3 and a Crew Health Care System rack.

Just over five months later, it was on its way to the station again on Discovery, this time on STS-105 launched Aug. 10, 2001. Its cargo included two science racks for the U.S. laboratory Destiny, six resupply stowage racks and four resupply stowage platforms. Total cargo weight was about 6,775 pounds.

On June 5, 2002, it launched on STS-111, this time in Endeavour’s payload bay. Leonardo brought a total of 8,062 pounds of supplies and equipment to the station, including a new science rack to house microgravity experiments and a glovebox for experiments that require isolation. In addition to carrying home the results of several science experiments, Leonardo returned to Earth more than 4,000 pounds of equipment and supplies no longer needed aboard the station.

After a shuttle stand-down after the loss of Columbia, Leonardo found itself back in Discovery’s cargo bay for STS-121, launched July 4, 2006. It carried food, clothing and consumables on five resupply stowage racks and three resupply stowage platforms. Also aboard was a minus 80 lab freezer, a European Modular Cultivation System for biology experiments, the Oxygen Generation System and a new cycle ergometer.

STS-126, an almost 16-day flight by Endeavour launched Nov. 14, 2008, marked Leonardo’s next visit to the station. It carried a record 14,000 pounds of equipment and supplies for the ISS. Major cargo included two crew quarters racks, the Advanced Resistive Exercise Device, two water reclamation racks, a waste and hygiene compartment and a galley.

Leonardo’s final flight as an MPLM was aboard Discovery on STS-131, launched April 5, 2010. Its cargo included the third minus 80-degree freezer, a window orbital research facility, a crew quarters rack, a resistive exercise rack and resupply stowage racks and platforms.

Two additional MPLMs were built by the Italian Space Agency. The second, Raffaello, flew three missions to the station and is scheduled to fly again on STS-135. The third, Donatello, never flew in space.

On STS-133, again on Discovery, Leonardo will be attached to the station as the PMM. Modifications before this flight included enhanced shielding and modifications to allow station crew members access to its internal equipment.

Its final cargo for the station includes an experiment rack, six resupply stowage platforms and five resupply stowage racks, as well as two integrated stowage platforms. The experiment rack, Express Rack 8, is designed to support and store a variety of experiments.

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Tuesday, February 22, 2011

STS-133 Crew Arrives at Kennedy


At NASA's Kennedy Space Center in Florida, space shuttle Discovery's STS-133 pose for a photo on the Shuttle Landing Facility runway after arriving in T-38 jets.

From left, are Nicole Stott, Michael Barratt, Steve Bowen and Alvin Drew, pilot Eric Boe and Commander Steve Lindsey.

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Monday, February 21, 2011

Kennedy Adds Florida Touch to 9/11 Flag


The contributions of NASA and Kennedy Space Center were stitched into the fabric of one of the nation's most recognizable symbols Friday when flags from Florida's Spaceport were sewn into an American Flag recovered near ground zero following the Sept. 11, 2001, attacks.

"The National 9/11 Flag" is on a cross-country journey to be restored to its original 13-stripe design using pieces of fabric from American flags destined for retirement in all 50 states. The Kennedy Space Center Visitor Complex was the official stop for the state of Florida on Feb. 18.

"For our site to be chosen, you know, on one hand I believe is all together fitting and proper because what we do at Kennedy Space Center is dare mighty things on behalf of the American people and all of humankind," said Joe Dowdy, special operations manager at Kennedy. "Some of that involves sacrifice and certainly this flag is an incredible demonstration of what free people sometimes have to be called upon to do, to sacrifice even their own lives."

The Brevard Police and Fire Pipes and Drums kicked off the stitching ceremony, followed by the United States Air Force 45th Space Wing Honor Guard stationed at nearby Patrick Air Force Base and more than a dozen 9/11 first responders.

A host of Floridians were invited to take part in the stitching ceremony, including Danny McKnight, the retired Army Colonel who led the ground convoy in 1993's battle of Mogadishu, Somalia, the combat depicted in the film "Black Hawk Down."

Craig Carson, an agent with the Brevard County Sheriff's Office who was nominated to take part in the ceremony, spent eight to nine months helping with the recovery effort in New York City.

"It was miraculous," Carson said. "It seemed like the whole world showed up to New York City that day to help. It was amazing."

The flag has become one of the most enduring symbols of the recovery from the attack.

"A few days after the collapse of the World Trade Center this flag was hanging on a scaffolding at 90 West Street, which was a building directly south of the World Trade Center that was heavily damaged when the south tower collapsed," said Jeff Parness, director, founder and chairman of the “New York Says Thank You Foundation."

Charlie Vitchers, the construction superintendant for the cleanup of ground zero, sent a crew up to rescue the flag, Parness said. Seven years later, Vitchers donated the flag to the organization so it could make a new mark in American history.

LeRoy Haynes was a supervising fire marshal and commander of the Bronx/Queens Fire Department and was on the corner of New York City's Church and Vesey streets, headed to the emergency command center at the World Trade Center with co-workers when the first tower began to crumble.

"We all ran and that big cloud of dust and smoke started to come at me," Haynes recalled. "That cloud was coming faster than I could run, the wind blew my helmet off and at that point in time all I could do was dive under a car."

Haynes survived and gathered all the strength and spirit he could to help setup a triage center on Broadway later that day. Haynes said he remembered seeing the flag in the aftermath of the attack.

"The flag was a mess. It was full of holes, parts were burned, singed, and it looked like it had been in a war," Haynes said. "It was amazing that it was one of the few things still standing."

Earlier this year, "The National 9/11 Flag" became a symbol of healing at the funeral of 9-year-old Christina Taylor Green. Born Sept. 11, 2001, Green was killed at a town hall event held by Congresswoman Gabrielle Giffords in Tucson, Arizona, on Jan. 8, 2011. Giffords is the wife of STS-134 Commander Mark Kelly.

"We realize that there are so many things that will never be made whole again, but this flag can be made whole again," Parness said. "There's this cathartic element of 'Well, I can finally do something. I can hold this needle and thread and try to make this whole.'"

The flags of Kennedy join other rich pieces of history, including parts of the flag that President Abraham Lincoln was laid on in 1865 after he was shot at Ford's Theatre in Washington, D.C.

"I kind of think of America as this magnificent mosaic," Dowdy said. "It's composed of all these various events, various places that make us a very special country. So there's this wonderful parallel about what this flag represents and what we represent here at Kennedy."

The star-spangled banner, which brings new meaning to national collaboration, later stood proud amongst rockets and capsules from NASA's Mercury, Gemini and Apollo days at the visitor complex's Rocket Garden. Including hundreds of people at Kennedy, "The National 9/11 Flag" is estimated to have touched more than 100 million lives.

Once complete, "The National 9/11 Flag" will become a permanent collection of the National September 11 Memorial Museum being built at the World Trade Center site. There, America's flag can evoke a sense of pride, unity and hunger to keep achieving greatness, just as the nation's space program has for more than half a decade.

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Sunday, February 20, 2011

Cassini to Sample Magnetic Environment around Titan


NASA's Cassini spacecraft is set to skim close to Saturn's moon Titan on Friday, Feb. 18, to learn about the interaction between Titan and Saturn's magnetosphere, the magnetic bubble around the planet.

The closest approach will take place at 8:04 a.m. PST (4:04 p.m. UTC) and bring Cassini within about 3,650 kilometers (2,270 miles) of Titan's surface.

As Titan makes a complete 360-degree orbit around Saturn, the relative influence of the sun's illumination and the hot ionized gas trapped in the magnetic bubble changes. These factors are important for understanding the relationship between Titan and Saturn's magnetosphere. It is important to make measurements at a variety of locations in the Saturn magnetosphere, so this flyby will occur in a part of the magnetosphere that has been poorly sampled so far.

Previous flybys have shown the magnetic environment near Titan to be rather variable and unpredictable. For 12 hours before and after closest approach, the Cassini plasma spectrometer instrument will be pointing in a direction to capture ionized gas in the region.

At the same time, Cassini's radio science subsystem will be gathering sensitive gravity data from Titan to improve understanding of the structure of the interior. Collecting data like these will eventually enable scientists to determine whether Titan has an ocean under its crust.

Other instruments will also be collecting data, much of it pertaining to seasonal change. Titan is currently in northern spring, approaching northern summer, and scientists want to know what has changed with the north polar winter vortex weather pattern. The composite infrared spectrometer, for instance, will be mapping temperatures in Titan's stratosphere. The imaging science subsystem will also be monitoring the lakes, clouds and transport of aerosols in the Titan atmosphere.

This latest flyby is dubbed "T74," though planning changes early in the orbital tour have made this the 75th targeted flyby of Titan.

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 was designed, developed and assembled at JPL.

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Friday, February 18, 2011

Advanced NASA Instrument Gets Close-up on Mars Rocks


NASA's Mars Science Laboratory rover, Curiosity, will carry a next generation, onboard "chemical element reader" to measure the chemical ingredients in Martian rocks and soil. The instrument is one of 10 that will help the rover in its upcoming mission to determine the past and present habitability of a specific area on the Red Planet. Launch is scheduled between Nov. 25 and Dec. 18, 2011, with landing in August 2012.

The Alpha Particle X-Ray Spectrometer (APXS) instrument, designed by physics professor Ralf Gellert of the University of Guelph in Ontario, Canada, uses the power of alpha particles, or helium nuclei, and X-rays to bombard a target, causing the target to give off its own characteristic alpha particles and X-ray radiation. This radiation is "read by" an X-ray detector inside the sensor head, which reveals which elements and how much of each are in the rock or soil.

Identifying the elemental composition of lighter elements such as sodium, magnesium or aluminum, as well as heavier elements like iron, nickel or zinc, will help scientists identify the building blocks of the Martian crust. By comparing these findings with those of previous Mars rover findings, scientists can determine if any weathering has taken place since the rock formed ages ago.

All NASA Mars rovers have carried a similar instrument – Pathfinder's rover Sojourner, Spirit and Opportunity, and now Curiosity, too. Improvements have been made with each generation, but the basic design of the instrument has remained the same.

"APXS was modified for Mars Science Laboratory to be faster so it could make quicker measurements. On the Mars Exploration Rovers [Spirit and Opportunity] it took us five to 10 hours to get information that we will now collect in two to three hours," said Gellert, the intrument's principal investigator. “We hope this will help us to investigate more samples.”

Another significant change to the next-generation APXS is the cooling system on the X-ray detector chip. The instruments used on Spirit and Opportunity were able to take measurements only at night. But the new cooling system will allow the instrument on Curiosity to take measurements during the day, too.

The main electronics portion of the tissue-box-sized instrument lives in the rover's body, while the sensor head, the size of a soft drink can, is mounted on the robotic arm. With the help of Curiosity’s remote sensing instruments – the Chemistry and Camera (ChemCam) instrument and the Mastcam – the rover team will decide where to drive Curiosity for a closer look with the instruments, including APXS. Measurements are taken with the APXS by deploying the sensor head to make direct contact with the desired sample.

The rover’s brush will be used to remove dust from rocks to prepare them for inspection by APXS and by MAHLI, the rover’s arm-mounted, close-up camera. Whenever promising samples are found, the rover will then use its drill to extract a few grains and feed them into the rover’s analytical instruments, SAM and CheMin, which will then make very detailed mineralogical and other investigations.

Scientists will use information from APXS and the other instruments to find the interesting spots and to figure out the present and past environmental conditions that are preserved in the rocks and soils.

"The rovers have answered a lot of questions, but they've also opened up new questions," said Gellert. "Curiosity was designed to pick up where Spirit and Opportunity left off."

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Science Laboratory mission for the NASA Science Mission Directorate, Washington.

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Wednesday, February 16, 2011

Glory Promises New View of Perplexing Particles


Climatologists have known for decades that airborne particles called aerosols can have a powerful impact on the climate. However, pinpointing the magnitude of the effect has proven challenging because of difficulties associated with measuring the particles on a global scale.

Soon a new NASA satellite -- Glory -- should help scientists collect the data needed to provide firmer answers about the important particles. In California, engineers and technicians at Vandenberg Air Force Base are currently prepping Glory for a Feb. 23 launch.

Aerosols, or the gases that lead to their formation, can come from vehicle tailpipes and desert winds, from sea spray and fires, volcanic eruptions and factories. Even lush forests, soils, or communities of plankton in the ocean can be sources of certain types of aerosols.

The ubiquitous particles drift in Earth's atmosphere, from the stratosphere to the surface, and range in size from a few nanometers, less than the width of the smallest viruses, to several tens of micrometers, about the diameter of human hair.

The particles can directly influence climate by reflecting or absorbing the sun's radiation. In broad terms, this means bright-colored or translucent aerosols, such as sulfates and sea salt aerosols, tend to reflect radiation back towards space and cause cooling. In contrast, darker aerosols, such as black carbon and other types of carbonaceous particles, can absorb significant amounts of light and contribute to atmospheric warming.

Research to date suggests that the cooling from sulfates and other reflective aerosols overwhelms the warming effect of black carbon and other absorbing aerosols. Indeed, the best climate models available show that aerosol particles have had a cooling effect that has counteracted about half of the warming caused by the build-up of greenhouse gases since the 1880s.

"However, the models are far from perfect," said Glory Project Scientist Michael Mishchenko, a senior scientist at the Goddard Institute for Space Studies (GISS). "The range of uncertainty associated with the climate impact of aerosols is three or four times that of greenhouse gases," he said.

In comparison to greenhouse gases, aerosols are short-lived, and dynamic -- making the particles much harder to measure than long-lived and stable carbon dioxide. Aerosols usually remain suspended in the atmosphere for just a handful of days. Complicating matters, the particles can clump together to form hybrids that are difficult to distinguish.

In addition to scattering and absorbing light, aerosols can also modify clouds. They serve as the seeds of clouds, and can also affect cloud brightness and reflectivity, how long clouds last, and how much they precipitate. Reflective aerosols, like sulfates, for example, tend to brighten clouds and make them last longer, whereas black carbon from soot generally has the opposite effect.

Still, much remains unknown about aerosols and clouds. How do aerosols other than sulfates and black carbon affect clouds? How do aerosol impacts differ in warm and cold environments? Can infusions of aerosols near clouds spark self-reinforcing feedback cycles capable of affecting the climate?

The climate impact of clouds remains one of the largest uncertainties in climate science because of such unanswered questions. Some models suggest a mere 5 percent increase in cloud reflectivity could compensate for the entire increase in greenhouse gases from the modern industrial era, while others produce quite different outcomes.

Such unresolved issues prompted the Intergovernmental Panel on Climate Change (IPCC) to list the level of scientific understanding about aerosols as "low" in its last major report. Of the 25 climate models included by the IPCC in the Fourth Assessment Report, only a handful considered the scattering or absorbing effects of aerosol types other than sulfates.

"And less than a third of the models included aerosol impacts on clouds, even in a limited way, and those that did only considered sulfates," said Mian Chin, a physical scientist at NASA's Goddard Space Flight Center who specializes in modeling aerosols.

Glory, which contains an innovative aerosol-sensing instrument called the Aerosol Polarimetry Sensor (APS), aims to change this. By more accurately identifying a broad suite of aerosol types -- such as salt, mineral dust and smoke -- the instrument should help climatologists fill in key gaps in climate models.

While other NASA instruments -- including ground, aircraft, and satellite-based instruments -- have studied aerosols in the past, APS is NASA's first satellite-based instrument capable of measuring the polarization, the orientation of light-wave vibrations.

Raw sunlight, explained Mishchenko, is unpolarized. This means the waves oscillate in an unpredictable, random fashion as they move through space -- much like a rope would wiggle about if it had two people flapping its ends up and down in no particular pattern.

When light waves pass through certain types of filters called polarizers the waves are forced into a more ordered form. Imagine that wobbling rope trying to pass throw a narrow slit in a fence: only the waves vibrating at a certain angle could make it through. The result is polarized light, or light for which the waves only oscillate at specific angles. The surface of glass, sunglasses, even clouds of aerosol particles can polarize light.

APS's ability to measure the polarization of light scattered by aerosols and clouds is the key strength of the instrument. Other NASA satellite instruments have measured aerosols, but such instruments have typically done so by looking at the intensity of light -- the amplitude of the light waves -- not their polarization.

Yet, ground and aircraft-based studies, particularly those conducted with an aircraft instrument called the Research Scanning Polarimeter, which is quite similar to APS, show that polarized light contains the most information about aerosol features. "Earlier instruments can approximate the abundance of aerosol in general terms, but they leave much to be desired if you're trying to sort out the shape and composition of the particles," said APS Instrument Scientist Brian Cairns, also of GISS.

Large, spherical particles -- sea salt, for example -- leave a very different imprint on light in comparison to smaller and more irregularly-shaped particles such as black carbon. As a result, much like forensic scientists might study the details of blood droplets at a crime scene to reconstruct what happened, climatologists using Glory data will look to the polarization state of scattered light to work backwards and deduce the type of aerosol that must have scattered it.

Glory will not be the first Earth-observing satellite instrument to study polarization. French instruments that launched in 1996 and 2002 have as well, but the APS promises to be far more accurate and will look at the same particles from many more angles.

Nonetheless, interpreting Glory's APS data will be an extremely complex task. The mission will provide such a vast amount of new polarization data about aerosols that, in order to make sense of it, scientists will first have to validate APS science products with ground-based sensors scattered around the globe. Likewise, they will have to adapt and update mathematical techniques developed for an aircraft instrument to ensure they work well in a space environment.

All of this will take some time to refine and perfect. Mishchenko's team expects to release preliminary results as soon as possible after Glory launches, but he also expects to release improved and enhanced versions of Glory's APS data products over time.

A great deal of work lies ahead of Glory's science team and the aerosol science community more broadly, but the mission has the potential to produce profound advancements in understanding the perplexing particles. "Glory has the potential to offer a critical view of aerosols that we have never had from space before," said Glory's Deputy Project Scientist Ellsworth Welton.

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Tuesday, February 15, 2011

Comet Hunter's First Images on the Ground


Mission controllers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., have begun receiving the first of 72 anticipated images of comet Tempel 1 taken by NASA's Stardust spacecraft.

The first six, most distant approach images are available at and Additional images, including those from closest approach, are being downlinked in chronological order and will be available later in the day.

A news conference will be held at 12:30 p.m. PST (3:30 p.m. EST) to allow scientists more time to analyze the data and images.

Stardust-NExT is a low-cost mission that expands on the investigation of comet Tempel 1 initiated by NASA's Deep Impact spacecraft. JPL, a division of the California Institute of Technology in Pasadena, manages Stardust-NExT for NASA's Science Mission Directorate, Washington, D.C. Joe Veverka of Cornell University, Ithaca, N.Y., is the mission's principal investigator. Lockheed Martin Space Systems, Denver, built the spacecraft and manages day-to-day mission operations.

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Monday, February 14, 2011

Happy Valentine's Day from Mars


An image taken by the Context Camera on NASA's Mars Reconnaissance Orbiter shows a heart-shaped feature that the camera's team at Malin Space Science Systems, San Diego, wants to share with other Mars fans on St. Valentine's Day.

The feature is about 1 kilometer (0.6 mile) long, in the Arabia Terra region of Mars' northern hemisphere. It appears in an image taken on May 23, 2010. A small impact crater near the tip of the heart is responsible for the formation of the bright, heart-shaped feature. When the impact occurred, darker material on the surface was blown away, and brighter material beneath it was revealed. Some of this brighter material appears to have flowed further downslope to form the heart shape, as the small impact occurred on the blanket of material ejected from a much larger impact crater.

The Context Camera was provided by and is operated by Malin Space Science Systems, San Diego, Calif. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, Calif., manages the Mars Reconnaissance Orbiter for the NASA Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the spacecraft and operates it in partnership with JPL.

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Sunday, February 13, 2011

SDO Celebrates One Year Anniversary


On February 11, 2010, at 10:23 in the morning, NASA's Solar Dynamics Observatory (SDO) launched into space on an Atlas rocket from Cape Canaveral. A year later, SDO has sent back millions of stunning images of the sun and a host of new data to help us understand the complex star at the heart of our solar system.

"One of the highlights of the last year is just that everything worked so smoothly," says astrophysicist Dean Pesnell, the project scientist for SDO at NASA's Goddard Space Flight Center in Greenbelt, Md. "We turned it on in March and it immediately started sending us data at 150 megabits per second. It worked from the very get go."

The first things scientists and the public saw from SDO was an array of wonderfully detailed pictures of the sun. One of the three instruments on board, called the Atmospheric Imaging Assembly (AIA), captures a shot of the sun every 12 seconds in 10 different wavelengths -- each wavelength helps illuminate aspects of the sun at different temperatures. The images are all available in real time online for everyone to see.

"It's been great to watch how popular these images are," says Phil Chamberlin, another astrophysicist at Goddard and one of SDO's deputy project scientists. "The public has been extremely interested. And it's important that people see what the sun is doing and how it affects us."

These images have regularly caught solar flares, coronal mass ejections, filament eruptions and other space weather phenomena in the act. Such images are helping to flesh out such questions as why the sun's corona – its atmosphere – is thousands of times hotter than the surface of the sun. For example, given how quickly SDO takes its pictures, scientists were recently able to track plumes of plasma heating up as they moved from the sun's surface up into the corona.

Another fruitful area of research from SDO involves understanding the massive explosions on the sun's surface called solar flares. Scientists have been able to use the GOES spacecraft to look at X-rays emitted from solar flares for some 40 years. But observing them in X-rays means one can only see those parts of the flares that are about 10 million degrees Celsius. Other spacecraft have since shown the flares in other wavelengths, but SDO's ability to provide detailed images of the same event in so many wavelengths allows one to see different parts of the flare no matter what temperature. It now appears that flares may be more complex than previously known.

The other two instruments onboard SDO also have made a strong impact. The Extreme Ultraviolet Variability Experiment (EVE) examines the extreme ultraviolet photons from the sun that are responsible for heating in Earth's upper atmosphere. The Helioseismic and Magnetic Imager (HMI) observes how the magnetic fields across the surface of the sun change, as well as seismic activity across the sun. "These are the doorway to the interior of the sun," says Pesnell. "This is how we understand what's going on inside it."

One of SDO's greatest successes so far may be how well these three instruments coordinate with other spacecraft observing the sun. For example, the two STEREO spacecraft moved into position on opposite sides of the sun on February 6, 2011 and will continue towards the far side and all the way around again over the next eight years. For that entire time, STEREO and SDO together will offer scientists their first opportunity to watch the entire sun simultaneously. There are many clues that solar weather can be connected over distances up to a million miles, but this will be the first chance to see how flares on one side coordinate with flares on the other.

In addition, sun observers such as the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) can show the highest energy, highest temperature bursts on the sun. These can be overlaid on SDO's images to get a more comprehensive picture of each individual event. On January 28, 2011, for example, two bursts of plasma jumped out from each side of the sun simultaneously -- an example of unconfirmed theories that such things often happen 180 degrees apart. Luckily, RHESSI caught the same event in its images, offering an unprecedented chance to examine all parts of the bursts at all temperatures.

"It's not just SDO. It's RHESSI, STEREO, SDO's three instruments all together," says Chamberlin. "The whole is much greater than the sum of the individual parts. We've been talking about putting together this great Heliophysics observatory and this really is what we have."

SDO is the first mission in a NASA science program called Living With a Star, the goal of which is to develop the scientific understanding necessary to address those aspects of the sun-Earth system that directly affect our lives and society. NASA Goddard built, operates, and manages the SDO spacecraft for NASA's Science Mission Directorate in Washington.

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Thursday, February 10, 2011

Five Things About NASA's Valentine's Day Comet


Here are five facts you should know about NASA's Stardust-NExT spacecraft as it prepares for a Valentine's "date" with comet Tempel 1. Feel free to sing along!

1. "The Way You Look Tonight" - The spacecraft is on a course to fly by comet Tempel 1 on Feb. 14 at about 8:37 p.m. PST (11:37 p.m. EST) -- Valentine's Day. Time of closest approach to Tempel 1 is significant because of the comet's rotation. We won't know until images are returned which face the comet has shown to the camera.

2. "It's All Coming Back To Me Now" - In 2004, Stardust became the first mission to collect particles directly from a comet, Wild 2, as well as samples of interstellar dust. The samples were returned in 2006 via a capsule that detached from the spacecraft and parachuted to the ground at a targeted area in Utah. Mission controllers then placed the still-viable Stardust spacecraft on a flight path that could reuse the flight system, if a target of opportunity presented itself. Tempel 1 became that target of opportunity.

3. "The First Time Ever I Saw Your Face" - The Stardust-NExT mission will allow scientists for the first time to look for changes on a comet's surface that occurred after one orbit around the sun. Tempel 1 was observed in 2005 by NASA's Deep Impact mission, which put an impactor on a collision course with the comet. Stardust-NExT might get a glimpse of the crater left behind, but if not, the comet would provide scientists with previously unseen areas for study. In addition, the Stardust-NExT encounter might reveal changes to Tempel 1 between Deep Impact and Stardust-Next, since the comet has completed an orbit around the sun.

4. "The Wind Beneath My Wings" - This Tempel 1 flyby will write the final chapter of the spacecraft's success story. The aging spacecraft approached 12 years of space travel on Feb. 7, logging almost 6 billion kilometers (3.5 billion miles) since launch. The spacecraft is nearly out of fuel. The Tempel 1 flyby and return of images are expected to consume the remaining fuel.

5. "Love is Now the Stardust of Yesterday" - Although the spacecraft itself will no longer be active after the flyby, the data collected by the Stardust-NExT mission will provide comet scientists with years of data to study how comets formed and evolved.

Bonus points for naming all the artists who sing these catchy tunes.

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Wednesday, February 9, 2011

NASA Announces Candidates for Cubesat Space Missions


NASA has selected 20 small satellites, including two from NASA's Jet Propulsion Laboratory in Pasadena, Calif., to fly as auxiliary payloads aboard rockets planned to launch in 2011 and 2012. The proposed CubeSats come from a high school in Virginia, universities across the country, NASA field centers and Department of Defense organizations.

CubeSats are a class of research spacecraft called nanosatellites. The cube-shaped satellites are approximately four inches long, have a volume of about one quart and weigh 2.2 pounds or less.

The selections are from the second round of the CubeSat Launch Initiative. The satellites are expected to conduct technology demonstrations, educational or science research missions. The selected spacecraft are eligible for flight after final negotiations when an opportunity arises.

The satellites come from the following organizations, which include the first high school proposal selected for a CubeSat flight:

-- Air Force Research Lab, Wright-Patterson Air Force Base, Ohio
-- Drexel University, Philadelphia
-- NASA's Goddard Space Flight Center, Greenbelt, Md. (two CubeSats)
-- NASA's Jet Propulsion Laboratory, Pasadena, Calif. (IPEX: Intelligent Payload Experiment, and LMRSat)
-- Naval Research Lab, Washington (two CubeSats)
-- Massachusetts Institute of Technology
-- Morehead State University, Morehead, Ky.
-- The Planetary Society, Pasadena, in partnership with NASA's Ames Research Center, Moffett Field, Calif.
-- Space and Missile Defense Command, Huntsville, Ala.
-- St. Louis University, St. Louis, Mo.
-- Thomas Jefferson High School, Alexandria, Va.
-- University of Colorado
-- University of Hawaii
-- University of Louisiana, Lafayette
-- University of New Mexico
-- U.S. Military Academy
-- U.S. Naval Academy

The first CubeSats to be carried on an expendable vehicle for the agency's Launch Services Program will comprise NASA's Educational Launch of Nanosatellite, or ELaNa, mission. ELaNa will fly on the Glory mission scheduled to lift off on Feb. 23. The 12 CubeSat payloads selected from the first round of the CubeSat Launch Initiative will have launch opportunities beginning later this year.

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Monday, February 7, 2011

NASA Finds Earth-size Planet Candidates in the Habitable Zone


Is our Milky Way galaxy home to other planets the size of Earth? Are Earth-sized planets common or rare? NASA scientists seeking answers to those questions recently revealed their discovery.

"We went from zero to 68 Earth-sized planet candidates and zero to 54 candidates in the habitable zone - a region where liquid water could exist on a planet’s surface. Some candidates could even have moons with liquid water," said William Borucki of NASA’s Ames Research Center, Moffett Field, Calif., and the Kepler Mission’s science principal investigator. "Five of the planetary candidates are both near Earth-size and orbit in the habitable zone of their parent stars."

Planet candidates require follow-up observations to verify they are actual planets.

"We have found over twelve hundred candidate planets - that’s more than all the people have found so far in history," said Borucki. "Now, these are candidates, but most of them, I’m convinced, will be confirmed as planets in the coming months and years."

The findings increase the number of planet candidates identified by Kepler to-date to 1,235. Of these, 68 are approximately Earth-size; 288 are super-Earth-size; 662 are Neptune-size; 165 are the size of Jupiter and 19 are larger than Jupiter. Of the 54 new planet candidates found in the habitable zone, five are near Earth-sized. The remaining 49 habitable zone candidates range from super-Earth size -- up to twice the size of Earth -- to larger than Jupiter. The findings are based on the results of observations conducted May 12 to Sept. 17, 2009 of more than 156,000 stars in Kepler’s field of view, which covers approximately 1/400 of the sky.

"The fact that we’ve found so many planet candidates in such a tiny fraction of the sky suggests there are countless planets orbiting stars like our sun in our galaxy," said Borucki. "Kepler can find only a small fraction of the planets around the stars it looks at because the orbits aren’t aligned properly. If you account for those two factors, our results indicate there must be millions of planets orbiting the stars that surround our sun."

“We’re about half-way through Kepler’s scheduled mission," said Roger Hunter, the Kepler project manager. "Today’s announcement is very exciting and portends many discoveries to come. It’s looking like the galaxy may be littered with many planets.”

Among the stars with planetary candidates, 170 show evidence of multiple planetary candidates, including one, Kepler-11, that scientists have been able to confirm that has no fewer than six planets.

"Another exciting discovery has been the tremendous variations in the structure of the confirmed planets – some have the density of Styrofoam and others are denser than iron. The Earth's density is in between."

"The historic milestones Kepler makes with each new discovery will determine the course of every exoplanet mission to follow," said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington.

Kepler, a space telescope, looks for planet signatures by measuring tiny decreases in the brightness of stars caused by planets crossing in front of them - this is known as a transit.

Since transits of planets in the habitable zone of sun-like stars occur about once a year and require three transits for verification, it is expected to take three years to locate and verify Earth-size planets orbiting sun-like stars.

The Kepler science team uses ground-based telescope and the Spitzer Space Telescope to perform follow-up observations on planetary candidates and other objects of interest found with the spacecraft. The star field that Kepler observes in the constellations Cygnus and Lyra can only be seen from ground-based observatories in spring through early fall. The data from these other observations helps determine which of the candidates can be validated as planets.

"The first four months of data have given us an enormous amount of interesting information for the science community to explore and to find the planets among the candidates that we have found," said Borucki. "Keep in mind, in the future, we’ll have even more data for small planets in and near the habitable zone for everyone to look at."

Kepler will continue conducting science operations until at least November 2012, searching for planets as small as Earth, including those that orbit stars in a warm habitable zone where liquid water could exist on the surface of the planet. Since transits of planets in the habitable zone of solar-like stars occur about once a year and require three transits for verification, it is expected to take three years to locate and verify Earth-size planets orbiting sun-like stars.

Borucki predicted that the search using the Kepler spacecraft’s continuous and long-duration capability will significantly enhance scientists’ ability to determine the distributions of planet size and orbital period in the future.

"In the coming years, Kepler’s capabilities will allow us to find Earth-size planets in the habitable zone of other stars," Borucki said. "Future missions will be developed to study the composition of planetary atmospheres to determine if they are compatible with the presence of life. The design for these missions depends of Kepler finding whether Earth-size planets in the habitable zone are common or rare."

The Kepler Mission team has discovered a total of 15 exoplanets, including the smallest known exoplanet, Kepler-10b.

"Kepler is providing data 100 times better than anyone has ever done before," said Borucki. "It’s exploring a new part of phase space, a new part of the universe that could not be explored without this kind of precision, so it’s producing absolutely beautiful data. We’re seeing the variability of stars like no one has ever seen before. We’re finding planets smaller than anyone has ever seen before, because the data quality is extremely good."

"In one generation we have gone from extraterrestrial planets being a mainstay of science fiction, to the present, where Kepler has helped turn science fiction into today's reality," said NASA Administrator Charles Bolden. "These discoveries underscore the importance of NASA's science missions, which consistently increase understanding of our place in the cosmos."

Kepler is NASA's tenth Discovery mission. Ames is responsible for the ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory, Pasadena, Calif., managed the Kepler mission development. Ball Aerospace and Technologies Corp., Boulder, Colo., was responsible for developing the Kepler flight system, and along with the Laboratory for Atmospheric and Space Physics at the University of Colorado, is supporting mission operations. Ground observations necessary to confirm the discoveries were conducted at the Keck I in Hawaii; Hobby-Ebberly and Harlan J. Smith 2.7m in Texas; Hale and Shane in California; WIYN, MMT and Tillinghast in Arizona, and the Nordic Optical in the Canary Islands, Spain.

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Sunday, February 6, 2011

LRO Could Have Given Apollo 14 Crew Another Majestic View


Although the Apollo 14 mission to the moon was filled with incredible sights and was completely successful -- it met all its science goals -- the crew experienced a bit of a disappointment at missing the spectacular view from the rim of a 1,000-foot-wide crater. They might have gazed into its depths if they had the high-resolution maps now available from NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft.

Pressure was on the Apollo 14 mission, launched January 31, 1971, from the start. The Apollo 13 landing had to be aborted because an oxygen tank explosion crippled the spacecraft as it was on its way to the moon. It was a heroic effort just to return the crew safely to Earth, but the Apollo 14 team knew a second failure would probably result in cancellation of the remaining Apollo missions.

Although nothing as catastrophic as an explosion threatened their mission, the Apollo 14 crew had to improvise their way out of some tense situations. On the way to the moon, the crew had to dock their spacecraft, the Command and Service Module "Kitty Hawk," to the spacecraft that would land on the moon, the Lunar Module "Antares." However, latches that would lock the two spaceships together refused to engage. Kitty Hawk pilot Stuart Roosa tried the docking maneuver six times over more than an hour and a half before the latches activated, linking the spacecraft so that mission commander Alan Shepard and Antares pilot Edgar Mitchell could transfer to the Antares lander. On the way down in Antares, the crew had to overcome computer and radar glitches in the system that was supposed to guide their landing. Even with the balky guidance system, they were able to pilot Antares to within 87 feet from the targeted landing point, at the time the most precise landing for the Apollo missions.

The site, which the crew named the "Fra Mauro Base," was the area to be explored by Apollo 13, a hilly zone about 300 miles from the edge of the 750-mile-wide Mare Imbrium basin formed long ago by the impact of a giant asteroid. The hills of Fra Mauro were believed to be made of rubble blasted from the Imbrium impact, and lunar geologists wanted the crew to collect rocks from the region so they could accurately date when giant impacts like Imbrium occurred on the moon.

Similar massive craters exist on Mercury and Mars, so it appears that the entire solar system experienced a chaotic period of "heavy bombardment" from enormous asteroids. Scientists were keen to date this event because it's very likely Earth was hit as well, and impacts of that scale would alter the evolution of life. However, on our world, such ancient craters have been erased by erosion from wind and water, as well as the recycling of the crust from its slow motion as a result of plate tectonics.

Shepard and Mitchell landed Feb. 5, and they performed two moonwalks, technically called "Extravehicular Activities," or EVAs, one on each day of the two days spent on the lunar surface. The first EVA went according to plan, with the deployment of the Apollo Lunar Surface Experiments Package, a suite of instruments that included a seismometer to measure moonquakes and laser reflectors to accurately measure changes in the Earth-moon distance using lasers fired from stations on Earth. During the second EVA, the crew hoped to reach the rim of Cone crater, a more recent impact crater about 1,000 feet wide a little over a mile from the Antares lander.

"An impact crater is like a drill," says Dr. James Rice of NASA's Goddard Space Flight Center, Greenbelt, Md. "The meteorite punches through layers of ground at the impact site and explodes, hurling this material outward. Surface material is scattered farthest, while the deepest material, which usually comes up in big chunks, remains closest to the crater rim. By collecting rocks as you get closer to a crater, you get a cross-section of the material beneath you without having to dig it up yourself. That's what the Apollo 14 crew did as they approached Cone crater – they wanted to get samples of the layers of rubble from the Mare Imbrium impact and see if Cone crater went deep enough to expose the bedrock beneath. The ejecta from the Imbrium impact where Apollo 14 landed may have come from up to 100 miles depth below the original lunar crust." Rice is an associate project scientist for LRO.

However, the terrain was hillier than expected, and the crew lost sight of the crater rim among the ridges of the hills. Eventually, they had to turn back because they needed to save enough oxygen and other supplies to return safely to the lander. At the time, they estimated they were close enough to the rim that rock samples collected where they stood would still represent the deep layers, but they were disappointed at missing the majestic view from the rim itself.

High-resolution photos of the area taken with LRO's Lunar Reconnaissance Orbiter Camera (LROC) reveal that they had come within about 30 yards of the rim, just a minuscule distance considering they had travelled over 250,000 miles to get there.

"The time lost in attempting to determine our exact position for collecting samples in order to satisfy the geologists, cost us significant time. We were essentially at the rim of Cone crater. We just didn't realize how close. It was just out of sight across the next rise a few yards away, when they decided our oxygen and water were too low to do anything but start back," said Antares pilot Edgar Mitchell.

"With the high-resolution photos we have from LRO today, combined with topographic maps made using LRO's laser-ranging instrument, they probably would have made it to the rim, because they would have known exactly where they were every step of the way," says Rice.

LRO has observed all the Apollo sites, and the LRO team is creating lunar maps with unprecedented accuracy that will guide future human and robotic explorers. The maps also will help identify unusual areas for a closer look, according to Rice, because they include data on mineral composition, water ice deposits, rough or unusual terrain, surface temperatures, and temperature changes.

Still, the Apollo 14 crew did an outstanding job with the maps available at the time, and the mission was a success, with nearly 100 pounds of rocks and soils collected and returned to Earth. Analysis of the decay of radioactive isotopes in the rocks dated giant impacts like Mare Imbrium at between 3.8 to 3.9 billion years old, about the time when life was emerging on Earth. The mission, which ended when the command module splashed down in the Pacific Ocean Feb. 9, 1971, still holds the record for the longest walk on the moon -- approximately 9,000 feet.

LRO was built and is managed by NASA Goddard. The research was funded by NASA's Exploration Systems Mission Directorate at NASA Headquarters in Washington.

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Friday, February 4, 2011

NASA Deputy Administrator Visits Nevada Innovation Sites


NASA Deputy Administrator Lori Garver visited Las Vegas today to meet with Nevada entrepreneurs and discuss innovations in space exploration and technology development critical to America's future in space.

Garver toured the facilities of Bigelow Aerospace, a company that has been developing expandable space habitats. NASA is evaluating Bigelow’s concept for an expandable module for the International Space Station. If approved, the Bigelow Expandable Activity Module, or BEAM, could be launched to the station using a commercial cargo flight and robotically attached to the orbiting laboratory.

Bigelow also has partnered with the Boeing Company on a crew capsule as part of NASA's Commercial Crew Development Program. NASA is working with multiple commercial partners to develop industry's capability to safely deliver crews and cargo to low Earth orbit.

"It's a pleasure to see the spark of innovation so vibrant here in Nevada," Garver said.

It's going to take our best minds and our best efforts to harness the full potential of our entrepreneurs, but with it, we can out-innovate, out-educate and out-build any competitor in the world."

As NASA focuses on a renewed program of technology development to reach destinations farther in the solar system, it also will continue a vigorous program of human spaceflight aboard the International Space Station and foster a growing commercial space industry with the capability to produce jobs and economic benefits.

"Commercial space in general and commercial crew in particular are vital to ensure that America survives and thrives in an increasingly global space industry," said the founder and president of Bigelow Aerospace, Robert T. Bigelow. "Innovation has always been the key to our country’s economy and we were thrilled to host the deputy administrator to show her what our entrepreneurial company has already accomplished."

The NASA Authorization Act of 2010, passed with strong bipartisan support, calls on NASA to pursue commercial access to space and extend the life of the space station to at least 2020. Along with these goals, the act directs the agency to open multiple pathways to innovate and develop new capabilities for the exploration missions of the future.

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Thursday, February 3, 2011

Surprise Hidden in Titan's Smog: Cirrus-Like Clouds


Every day is a bad-air day on Saturn's largest moon, Titan. Blanketed by haze far worse than any smog belched out in Los Angeles, Beijing or even Sherlock Holmes's London, the moon looks like a dirty orange ball. Described once as crude oil without the sulfur, the haze is made of tiny droplets of hydrocarbons with other, more noxious chemicals mixed in. Gunk.

Icky as it may sound, Titan is really the rarest of gems: the only moon in our solar system with an atmosphere worthy of a planet. This atmosphere comes complete with lightning, drizzle and occasionally a big, summer-downpour style of cloud made of methane or ethane -- hydrocarbons that are best known for their role in natural gas.

Now, thin, wispy clouds of ice particles, similar to Earth's cirrus clouds, are being reported by Carrie Anderson and Robert Samuelson at NASA's Goddard Space Flight Center in Greenbelt, Md. The findings, published February 1 in Icarus, were made using the Composite Infrared Spectrometer (CIRS) on NASA's Cassini spacecraft.

Unlike Titan's brownish haze, the ice clouds have the pearly white appearance of freshly fallen snow. Their existence is the latest clue to the workings of Titan's intriguing atmosphere and its one-way "cycle" that delivers hydrocarbons and other organic compounds to the ground as precipitation. Those compounds don't evaporate to replenish the atmosphere, but somehow the supply has not run out (yet?).

"This is the first time we have been able to get details about these clouds," says Samuelson, an emeritus scientist at Goddard and the co-author of the paper. "Previously, we had a lot of information about the gases in Titan's atmosphere but not much about the [high-altitude] clouds."

Puffy methane and ethane clouds had been found before by ground-based observers and in images taken by Cassini's imaging science subsystem and visual and infrared mapping spectrometer. Compared to those clouds, these are much thinner and located higher in the atmosphere. "They are very tenuous and very easy to miss," says Anderson, the paper's lead author. "The only earlier hints that they existed were faint glimpses that NASA's Voyager 1 spacecraft caught as it flew by Titan in 1980."

Out on a Limb

Even before Voyager 1 reached Titan, scientists knew the moon was wrapped in a thick atmosphere that probably contained hydrocarbons. Part of that atmosphere, Voyager found, is a haze so smothering that it hides every bit of the moon's surface.

Only a small amount of visible light penetrates this haze, or aerosol, so studies rely on instruments that operate at wavelengths beyond human sight. This is how Voyager learned that Titan's atmosphere is made mostly of nitrogen, as is Earth's. Unlike Earth's atmosphere, though, Titan's has neither oxygen nor water to speak of. Instead, it contains small amounts of organic materials, including members of the hydrocarbon family such as methane, ethane and propane.

Voyager also picked up indications that Titan's stratosphere, the second-lowest layer of its atmosphere, harbored "ices made from some exotic organic compounds," Samuelson says. "At the time, that was about all we could tell."

Fast-forward a quarter-century to mid-2006, past decades of research conducted from telescopes, past Cassini's arrival at Saturn, past the European Space Agency's Huygens probe landing on Titan and taking the first pictures of the surface, past the discovery of the methane and ethane clouds. At this point, Cassini continues to orbit Saturn and visit Titan and other moons periodically.

More than a half-dozen hydrocarbons have been identified in gas form in Titan's atmosphere, but many more probably lurk there. Researchers worldwide are looking for them, including Anderson and Samuelson, who are using the CIRS (pronounced "sears") instrument on Cassini.

Pinpointing the altitudes where such gases turn into ices is painstaking work. The researchers scan up and down the atmosphere, pausing at each altitude to catalog a slew of signals that have to be teased apart later so that the molecules can be identified. "You can learn a lot about a compound, even if you have no idea what it is, by looking at how it is distributed vertically," says Anderson. "Where does it accumulate? Where does it dissipate? How thick is the boundary? Is there layering going on?"

Anderson and Samuelson start a series of observations near Titan's north pole, at roughly the same latitudes Voyager looked at, 62 °N and 70 °N. On Earth, these would fall just inside and outside the ring for the Arctic Circle.

The team focuses on the observations made when CIRS is positioned to peer into the atmosphere at an angle, grazing the edge of Titan. This path through the atmosphere is longer than the one when the spacecraft looks straight down at the surface. Planetary scientists call this "viewing on the limb," and it raises the odds of encountering enough molecules of interest to yield a strong signal.

It works. When the researchers comb through their data, they succeed in separating the telltale signatures of ice clouds from the aerosol. "These beautiful, beautiful ice clouds are optically thin, and they're diffuse," says Anderson. "But we were able to pick up on them because of the long path lengths of the observations."

In addition to spotting the clouds, the researchers gather enough information to measure the sizes of the ice particles. The results get reported in a January 2010 Icarus paper by Anderson, Samuelson, their Goddard colleague Gordon Bjoraker and Richard Achterberg, a University of Maryland staff member working at Goddard.

"That was convincing evidence," Anderson says. "What Voyager had seen was real."

That Sinking Feeling

Clouds on Titan can't be made from water because of the planet's extreme cold. "If Titan has any water on the surface, it would be solid as a rock," says Goddard's Michael Flasar, the Principal Investigator for CIRS.

Instead, the key player is methane. The action starts high in the atmosphere, where some of the methane gets broken up and reforms into ethane and other hydrocarbons, or combines with nitrogen to make materials called nitriles. Any of these compounds can probably form clouds if enough accumulates in a sufficiently cold area.

The cloud-forming temperatures occur in the "cold, cold depths of Titan's stratosphere," says Anderson. Researchers think that the compounds get moved downward by a constant stream of gas flowing from the pole in the warmer hemisphere to the pole in the colder hemisphere. There, the gas sinks.

This circulation pattern steals so much gas from the warmer hemisphere that researchers can measure the imbalance. The influx of all this gas gives the colder hemisphere more clouds. "At colder temperatures, more gas will condense anyway," Anderson explains, "and on top of that, the atmosphere dumps a whole bunch of extra gas there."

She and Samuelson think this is why the ice clouds were first spotted in the north. When Voyager flew by in November 1980, the north had just crossed from winter into spring. And the north was in mid-winter when the team conducted their early observations. (One Titan year lasts 29-1/2 Earth years, so spring came again to Titan's north in August 2009.)

Still, the team figured, the south shouldn't lack ice clouds; it should just have fewer of them. "For 30 years, Bob [Samuelson] had been saying that these clouds should exist in the southern hemisphere," says Anderson, "so we decided to look."

The team checked Titan's southern hemisphere (at 58 °S latitude) and both sides of the equator (15 °N and 15 °S). Sure enough, they spotted clouds in all three locations. And as predicted, the clouds in the north were more plentiful -- in fact, three times more plentiful -- than those just south of the equator.

"The fact that the clouds are more enhanced at the cold polar region is a promising sign," says Flasar. "It strengthens this idea that the molecules making up these clouds are being carried downward by this global circulation."

Exotic Ices

Part of Titan's allure has long been the organic compounds in the atmosphere, especially because some are thought to be involved in the events that led to life on Earth. One of those is cyanoacetylene, a member of the nitrile family. The compound's distinctive signature made it the first to be picked up in the northern ice clouds by Voyager 1 and by Anderson and Samuelson.

To make a connection between these molecules and life isn't the point for Anderson, though. "I just love ices and aerosols," she says, "and Titan is this great natural laboratory for studying them."

As the researchers continue to identify compounds in Titan's atmosphere, the next likely candidate for an ice is hydrogen cyanide, a nitrile with an earthly reputation as a poison. In the aerosol, the team is investigating an intriguing feature in the data that seems to represent larger hydrocarbons than anybody has identified before, according to Samuelson. Early clues suggest the signature could indicate polycyclic aromatic hydrocarbons (PAHs), which typically get noticed on Earth as pollutants released by the burning of fossil fuels. In space, PAHs form in the regions where stars are born and die.

Each nugget of information like this is helping scientists piece together the life cycle and ultimate fate of Titan's hydrocarbons, which never reenter the atmosphere via evaporation. "They fall to the surface, and it's a dead end," says Samuelson, "and yet Titan's atmosphere still has methane in it. We are trying to find out why."

The Great Switcheroo

At first, Titan's frozen nitriles seem entirely unrelated to Earth clouds. Even putting aside their exotic ingredients, they form much higher in the atmosphere: at altitudes of about 30 to 60 miles (in the stratosphere) versus no more than 11 miles (in the troposphere) for nearly all Earth clouds.

But Earth does have a few polar stratospheric clouds that appear over Antarctica (and sometimes in the Arctic) during winter. These clouds form in the exceptionally cold air that gets trapped in the center of the polar vortex, a fierce wind that whips around the pole high in the stratosphere. This is the same region where Earth's ozone hole is found.

Titan has its own polar vortex and may even have a counterpart to our ozone hole. The degree of similarity is intriguing, says Flasar, given the different compositions and chemistries of the stratospheric clouds on Earth versus Titan.

"We are starting to find out how similar Titan's clouds are to Earth's," says Samuelson. "How do they compare? How do they not compare?"

The big test of scientists' understanding of Titan's atmosphere will come in 2017, when summer comes to the north and the south plunges into winter. "We expect to find a complete reversal in the circulation of gas then," says Anderson. "The gas should start to flow from the north to the south. And that should mean most of the high-altitude ice clouds will be in the southern hemisphere."

Other major changes are in store for Titan then, Flasar adds, including the disappearance of the fierce winds around the north pole. "The big question is: will the vortex go out with a bang or whimper?" he says. "On Earth, it goes out with a bang. It's very dramatic. But on Titan, maybe the vortex just gradually fizzles out like the smile of the Chesire cat."

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Wednesday, February 2, 2011

NASA Satellites Capture Data on Monster Winter Storm Affecting 30 States


One of the largest winter storms since the 1950s is affecting 30 U.S. states today with snow, sleet, freezing rain and rain. NASA satellites have gathering data on the storm that stretches from Texas and the Rockies to the New England states.

NASA's Aqua and Terra satellites have been providing visible, infrared and microwave looks at the storm system's clouds, precipitation, temperatures and extent.

Visible and infrared images and animations of the storm's clouds and movement are created every 15 minutes by the NASA GOES Project at NASA's Goddard Space Flight Center, Greenbelt, Md. using data from GOES-11 and GOES-13, the Geostationary Operational Environmental Satellites. The GOES-13 and GOES-11 satellites that cover the eastern and western U.S., respectively, are operated by NOAA.

A visible image captured by the GOES-13 satellite this morning, Feb. 1 at 1401 UTC (9:01 a.m. EST) showed the low pressure area stretching from the Colorado Rockies and Texas east to New England and a massive area of clouds over the Midwest. The image showed what appeared to be "tails" over Texas and the Gulf coast. Those "tails" are areas where severe thunderstorms are possible today. To see an animation of the last two days of GOES-13 satellite images that show the progression of the storm, go to:

Another amazing satellite image created at NASA Goddard involved data from the Moderate Resolution Imaging Spectroradiometer (MODIS) that flies aboard NASA's Terra satellite. Because of its massive size, three MODIS images were combined to create an image of the storm system. The images were captured each time the Terra satellite passed over the U.S. on January 31 at 10:30 a.m., 12:05 p.m., and 1:45 p.m. Eastern Time (15:30, 17:05, and 18:45 UTC). The image clearly shows snow on the ground from Pennsylvania into the New England states, while the large area of clouds associated with the storm lie to the west. The image has a resolution of one kilometer per pixel.

NASA's Jet Propulsion Laboratory in Pasadena, Calif. supplied infrared data of the storm system. The Atmospheric Infrared Sounder (AIRS) instrument that flies aboard NASA's Aqua satellite captured infrared imagery of the storm on Jan. 31, 2011 at 18:47 UTC (1:47 p.m. EST). The image showed the early stages of a developing storm in the plains and Midwestern states and highlighted a preponderance of cold air in Canada and the northern U.S. that set the stage for the snowfall today.

A visible image created from AIRS data on Jan. 31 showed thickening clouds along a developing intense front in the plains and Midwestern states that will produce excessive snow, freezing rain, sleet, and wind in those areas today. The associated low pressure area guiding the storm will slide from Texas through the Mississippi Valley, Ohio Valley and then into New England.

NOAA's National Weather Service noted in their discussion today that this winter storm could easily be "one of the worst this season with blizzard conditions throughout much of the Midwest states, severe ice accretion from the middle Mississippi River valley eastward through parts of the Ohio Valley and into southern New England and heavy rain and severe thunderstorms over the deep south."

Nine states are under blizzard warnings today and Chicago is expecting two feet of snow by the evening commute and overnight. Residents of Oklahoma City are experiencing snow and gusty winds and expecting up to one and a half feet of snow today. On the southern end of this storm system, severe storms moved through Texas this morning, while areas from Birmingham to Memphis and Atlanta may also receive severe weather and between 1 and 2 inches of heavy rainfall as the system continues move east today.

The U.S. northeast is expecting snow, sleet and rain. Some northeastern U.S. cities have already recorded record snowfall and more is expected from this storm. Philadelphia has already recorded 37 inches of snow and New York City has received 56 inches. Philadelphia is expecting freezing rain today while New York City is forecast to receive between 3 and 6 inches of snow and sleet and between a quarter to 4 tenths of an inch of ice accumulation by late Wednesday.

As the system continues east, the National Weather Service is forecasting a large snowfall for New England. Boston is forecast to receive between 8 and 18 inches of snow and Portland, Maine, is expected to receive between 11 and 17 inches. It has already been a long winter in the U.S. northeast and today is the first day of February, a month known to be the snowiest of the season.

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Tuesday, February 1, 2011

Cassini Sends Back Postcards of Saturn Moons


On Jan. 31, 2011, NASA's Cassini spacecraft passed by several of Saturn's intriguing moons, snapping images along the way. Cassini passed within about 60,000 kilometers (37,282 miles) of Enceladus and 28,000 kilometers (17,398 miles) of Helene. It also caught a glimpse of Mimas in front of Saturn's rings. In one of the images, Cassini is looking at the famous jets erupting from the south polar terrain of Enceladus.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute in Boulder, Colo.

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