Chase Storm on Saturn

With the help of amateur astronomers, the composite infrared spectrometer instrument aboard NASA's Cassini spacecraft has taken its first look at a massive blizzard in Saturn's atmosphere. The instrument collected the most detailed data to date of temperatures and gas distribution in that planet's storms.

The data showed a large, turbulent storm, dredging up loads of material from the deep atmosphere and covering an area at least five times larger than the biggest blizzard in this year's Washington, D.C.-area storm front nicknamed "Snowmageddon."

"We were so excited to get a heads-up from the amateurs," said Gordon Bjoraker, a composite infrared spectrometer team member based at NASA's Goddard Space Flight Center in Greenbelt, Md. Normally, he said, "Data from the storm cell would have been averaged out."

Cassini's radio and plasma wave instrument and imaging cameras have been tracking thunder and lightning storms on Saturn for years in a band around Saturn's mid-latitudes nicknamed "storm alley." But storms can come and go on a time scale of weeks, while Cassini's imaging and spectrometer observations have to be locked in place months in advance.

The radio and plasma wave instrument regularly picks up electrostatic discharges associated with the storms, so team members have been sending periodic tips to amateur astronomers, who can quickly go to their backyard telescopes and try to see the bright convective storm clouds. Amateur astronomers including Anthony Wesley, Trevor Barry and Christopher Go got one of those notices in February and were able to take dozens of pictures over the next several weeks.

In late March, Wesley, an amateur astronomer from Australia who was actually the first person to detect the new dark spot caused by an impact on Jupiter last summer, sent Cassini scientists an e-mail with a picture of the storm.

"I wanted to be sure that images like these were being seen by the Cassini team just in case this was something of interest to be imaged directly by Cassini or the Hubble Space Telescope," Wesley wrote.

Cassini scientists eagerly pored through the images, including a picture of the storm at its peak on March 13 by Go, who lives in the Philippines.

By a stroke of luck, the composite infrared spectrometer happened to be targeting the latitude of the storms. The instrument's scientists knew there could be storms there, but didn't know when they might be active.

Data obtained by the spectrometer on March 25 and 26 showed larger than expected amounts of phosphine, a gas typically found in Saturn's deep atmosphere and an indicator that powerful currents were dredging material upward into the upper troposphere. The spectrometer data also showed another signature of the storm: the tropopause, the dividing line between the serene stratosphere and the lower, churning troposphere, was about 0.5 Kelvin (1 degree Fahrenheit) colder in the storm cell than in neighboring areas.

"A balloonist floating about 100 kilometers down from the bottom of Saturn's calm stratosphere would experience an ammonia-ice blizzard with the intensity of Snowmageddon," said Brigette Hesman, a composite infrared spectrometer team member who is an assistant research scientist at the University of Maryland. "These blizzards appear to be powered by violent storms deeper down - perhaps another 100 to 200 kilometers down - where lightning has been observed and the clouds are made of water and ammonia."

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 composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md., where the instrument was built.

Water-ice and carbon-based organic compounds on the surface of an asteroid

Scientists using a NASA funded telescope have detected water-ice and carbon-based organic compounds on the surface of an asteroid. The cold hard facts of the discovery of the frosty mixture on one of the asteroid belt's largest occupants, suggests that some asteroids, along with their celestial brethren, comets, were the water carriers for a primordial Earth. The research is published in today's issue of the journal Nature.

"For a long time the thinking was that you couldn't find a cup's worth of water in the entire asteroid belt," said Don Yeomans, manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "Today we know you not only could quench your thirst, but you just might be able to fill up every pool on Earth – and then some."

The discovery is a result of six years of observing asteroid 24 Themis by astronomer Andrew Rivkin of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. Rivkin, along with Joshua Emery, of the University of Tennessee in Knoxville, employed the NASA Infrared Telescope Facility to take measurements of the asteroid on seven separate occasions beginning in 2002. Buried in their compiled data was the consistent infrared signature of water ice and carbon-based organic materials.

The study's findings are particularly surprising because it was believed that Themis, orbiting the sun at "only" 479 million kilometers (297 million miles), was too close to the solar system's fiery heat source to carry water ice left over from the solar system's origin 4.6 billion years ago.

Now, the astronomical community knows better. The research could help re-write the book on the solar system's formation and the nature of asteroids.

"This is exciting because it provides us a better understanding about our past – and our possible future," said Yeomans. "This research indicates that not only could asteroids be possible sources of raw materials, but they could be the fueling stations and watering holes for future interplanetary exploration."

Rivkin and Emory's findings were independently confirmed by a team led by Humberto Campins at the University of Central Florida in Orlando.

NASA detects, tracks and characterizes asteroids and comets passing close to Earth using both ground- and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them, and plots their orbits to determine if any could be potentially hazardous to our planet.

X-48B:first phase of flight tests

A team led by NASA and The Boeing Company has completed the first phase of flight tests on the subscale X-48B blended wing body aircraft at the agency's Dryden Flight Research Center in Edwards, Calif.

The remotely piloted, 500-pound airplane with the silhouette resembling a manta ray – also called a hybrid wing body -- is a tool of NASA's new Environmentally Responsible Aviation, or ERA, Project, which aims to develop the technology needed to create a quieter, cleaner, and more fuel-efficient airplane for the future.

A flying test bed such as the X-48B enables NASA to assess and validate the key technologies. The recently concluded flight tests ascertained the handling and flying qualities of such an aircraft at speeds typical of landings and takeoffs.

"This project is a huge success," said Fay Collier, manager of the ERA Project in NASA's Aeronautics Research Mission Directorate. "Bottom line: the team has proven the ability to fly tailless aircraft to the edge of the low-speed envelope safely."

Until recently, Collier was principal investigator for NASA's Subsonic Fixed Wing Project, which established the partnership with Boeing to conduct initial, fundamental technology development efforts with the X-48B. The ERA Project he now leads is part of a new research program NASA initiated to help further mature promising technology before transfer to industry.

The team completed the 80th and last flight of the project's first phase on March 19, 2010, almost three years after the X-48B's first flight on July 20, 2007.

In addition to NASA and Boeing, the team includes Cranfield Aerospace Limited of the United Kingdom, and the U.S. Air Force Research Laboratory of Dayton, Ohio.

In the mid-2000s, NASA identified low-speed flight controls as a development challenge for aircraft such as the hybrid wing body. This challenge, and the challenge of building a non-circular, pressurized fuselage structure, have been the initial focuses of research since then. The ultimate goal is to develop technology for an environmentally friendly aircraft that makes less noise, burns less fuel, and emits less noxious exhaust.

"These 80 research flights provided engineers with invaluable test data and allowed the team to completely meet the initial project test objectives," said Tim Risch, Dryden's X-48B project manager.

The milestones accomplished by the team focused on three main technical objectives: flight envelope expansion, aircraft performance characterization, and validation of flight control software limiters.

The first objective, envelope expansion, consisted of 20 flights over a year-long period. For these flights, the aircraft was flown through a variety of maneuvers intended to define the overall flight capabilities and discern the general stability and handling characteristics of the aircraft. Completion of these tests resulted in a preliminary flight envelope adequate for transition to higher risk testing.

The second objective, aircraft performance characterization, focused on stall testing to define the boundaries of controlled flight, engine-out maneuvering to understand how to control the aircraft if one or more engines malfunctioned, and parameter identification flights to evaluate how movements of flight control surfaces affected the airplane's performance.

In 52 flights from July 2008 through December 2009, engineers quantified the dynamic response of the aircraft by sending computer commands to the X-48B's flight control surfaces and measuring how quickly the plane responded to the inputs.

The third and most important objective were limiter assaults, in which the remote pilot deliberately exceeded the defined boundaries of controllability – such as angle of attack, sideslip angle and acceleration -- to see whether the airplane's computer could keep it flying steady. Eight flight tests validated the programmed limiters and gave the team confidence that a robust, versatile, and safe control system could be developed for such an aircraft.

Tests with the X-48B will continue later this year, after a new flight computer is installed and checked out. The next series of flight tests will focus on additional parameter identification investigations.

NASA has a second hybrid wing body aircraft, the X-48C, which it has modified for a noise profile even lower than the X-48B's, and is preparing for test flights to investigate other controllability factors.

NASA Ames Research Center Support GloPac Science Mission

Some of NASA’s best talent is hidden behind the scenes when Earth science airborne campaigns are being planned and executed around the world. As part of NASA’s Airborne Science Program, several groups from NASA’s Ames Research Center, Moffett Field, Calif., provide key support to ensure the success of these missions.

Today, their legacy continues as they develop the science infrastructure using NASA’s newest tool in its airborne research fleet, the Global Hawk Unmanned Aircraft System (UAS).

“It is NASA’s first fully autonomous, high altitude, long endurance UAS. It will give scientists the ability to carry payloads to remote regions of the atmosphere and remain there for long durations collecting key measurements,” said Michael Craig, research manager at NASA’s Ames and project manager for the first Earth science Global Hawk experiment, known as the Global Hawk Pacific (GloPac) mission.

The Global Hawk has a flight endurance of more than 30 hours, can reach a maximum altitude of 65,000 feet, a range of 11,000 nautical miles, and a payload capability of more than 1,500 lbs. of scientific instruments. No other manned or unmanned aircraft can meet these combined performance capabilities.

NASA's Dryden Flight Research Center, Edwards, Calif., has acquired three of the first seven Global Hawk aircraft produced for the U.S. Air Force and, through an agreement with the manufacturer, Northrop Grumman Corp., Los Angeles, is modifying them for Earth science operations.

The GloPac mission, now underway at Dryden, has successfully completed its first flights. NASA Ames played a vital role in providing the management, flight planning, meteorological constraints and science instrument infrastructure and communications required with this new platform. GloPac is funded in part by the Airborne Science Program within the Earth Science Division of NASA's Science Mission Directorate in Washington.

“It’s really amazing to see all these state-of-the-art technologies and hard work come together to create such an outstanding capability,” said Craig.

GloPac is being conducted in support of NASA’s Aura and A-Train satellite Earth Observation System constellation. The mission consists of four to five science flights that are taking the aircraft over the Pacific south to the equator, north to the Arctic and to the west past Hawaii. The payload includes 11 science instruments that are collecting a wide range of atmospheric data, including trace gases and aerosol composition, as well as meteorological parameters.

“These observations are important for understanding processes that control ozone-depleting substances, greenhouse gases that contribute to climate change and pollution that impacts air quality,” explained Craig.

There are over 100 people working on the GloPac mission. This includes managers, pilots, scientists, engineers, aircraft ground crew, and other support staff from NASA, the National Oceanic and Atmospheric Administration (NOAA), several universities and others. The NASA team includes members from Ames, Dryden, Goddard Space Flight Center, Greenbelt, Md., Jet Propulsion Laboratory, Pasadena, Calif., and NASA Headquarters in Washington, DC.

“This team is transforming the way Earth Science airborne missions will be performed in the future,” said Craig.

Several other teams are developing new research missions and applications for the Global Hawk, and NASA is now working on a mobile control center that will give the aircraft truly global coverage. Later this summer, NASA will use the Global Hawk to monitor hurricane development and intensification. Scientists predict that in future years, the aircraft could be used to monitor a number of natural and human-made changes to our planet, including climate change, ice thicknesses, and ecosystems.

NASA's New Eye on the Sun Delivers Stunning First Images

NASA's recently launched Solar Dynamics Observatory, or SDO, is returning early images that confirm an unprecedented new capability for scientists to better understand our sun’s dynamic processes. These solar activities affect everything on Earth.

Some of the images from the spacecraft show never-before-seen detail of material streaming outward and away from sunspots. Others show extreme close-ups of activity on the sun’s surface. The spacecraft also has made the first high-resolution measurements of solar flares in a broad range of extreme ultraviolet wavelengths.

"These initial images show a dynamic sun that I had never seen in more than 40 years of solar research,” said Richard Fisher, director of the Heliophysics Division at NASA Headquarters in Washington. "SDO will change our understanding of the sun and its processes, which affect our lives and society. This mission will have a huge impact on science, similar to the impact of the Hubble Space Telescope on modern astrophysics.”

NASA Celebrates 40th Anniversary of Earth Day

NASA celebrates the 40th anniversary of Earth Day on the National Mall in Washington beginning Saturday, April 17. Included in the events is the 'NASA Village,' which contains three domed tents, and will highlight the use of NASA science and technology to advance knowledge and awareness about our home planet and sustain our environment. The NASA Science Tent which will host exhibits and hands-on demonstrations. The NASA Cinema Tent will feature multimedia presentations by NASA scientists and others. The NASA Technology Tent will present exhibits and demonstrations on a wide range of NASA environmental technologies.

Einstein's theory is still the best game in town

Two new and independent studies have put Einstein's General Theory of Relativity to the test like never before. These results, made using NASA's Chandra X-ray Observatory, show Einstein's theory is still the best game in town.

Each team of scientists took advantage of extensive Chandra observations of galaxy clusters, the largest objects in the Universe bound together by gravity. One result undercuts a rival gravity model to General Relativity, while the other shows that Einstein's theory works over a vast range of times and distances across the cosmos.

The first finding significantly weakens a competitor to General Relativity known as "f(R) gravity".

"If General Relativity were the heavyweight boxing champion, this other theory was hoping to be the upstart contender," said Fabian Schmidt of the California Institute of Technology in Pasadena, who led the study. "Our work shows that the chances of its upsetting the champ are very slim."

In recent years, physicists have turned their attention to competing theories to General Relativity as a possible explanation for the accelerated expansion of the universe. Currently, the most popular explanation for the acceleration is the so-called cosmological constant, which can be understood as energy that exists in empty space. This energy is referred to as dark energy to emphasize that it cannot be directly detected.

In the f(R) theory, the cosmic acceleration comes not from an exotic form of energy but from a modification of the gravitational force. The modified force also affects the rate at which small enhancements of matter can grow over the eons to become massive clusters of galaxies, opening up the possibility of a sensitive test of the theory.

Schmidt and colleagues used mass estimates of 49 galaxy clusters in the local universe from Chandra observations, compared them with theoretical model predictions and studies of supernovas, the cosmic microwave background, and the large-scale distribution of galaxies.

They found no evidence that gravity is different from General Relativity on scales larger than 130 million light years. This limit corresponds to a hundred-fold improvement on the bounds of the modified gravitational force's range that can be set without using the cluster data.

"This is the strongest ever constraint set on an alternative to General Relativity on such large distance scales," said Schmidt. "Our results show that we can probe gravity stringently on cosmological scales by using observations of galaxy clusters."

The reason for this dramatic improvement in constraints can be traced to the greatly enhanced gravitational forces acting in clusters as opposed to the universal background expansion of the universe. The cluster-growth technique also promises to be a good probe of other modified gravity scenarios, such as models motivated by higher- dimensional theories and string theory.

A second, independent study also bolsters General Relativity by directly testing it across cosmological distances and times. Up until now, General Relativity had been verified only using experiments from laboratory to Solar System scales, leaving the door open to the possibility that General Relativity breaks down on much larger scales.

To probe this question, a group at Stanford University compared Chandra observations of how rapidly galaxy clusters have grown over time to the predictions of General Relativity. The result is nearly complete agreement between observation and theory.

“Einstein's theory succeeds again, this time in calculating how many massive clusters have formed under gravity's pull over the last five billion years,” said David Rapetti of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University and SLAC National Accelerator Laboratory, who led the new study. “Excitingly and reassuringly, our results are the most robust consistency test of General Relativity yet carried out on cosmological scales."

Rapetti and his colleagues based their results on a sample of 238 clusters detected across the whole sky by the now-defunct ROSAT X-ray telescope. These data were enhanced by detailed mass measurements for 71 distant clusters using Chandra, and 23 relatively nearby clusters using ROSAT, and combined with studies of supernovas, the cosmic microwave background, the distribution of galaxies and distance estimates to galaxy clusters.

Galaxy clusters are important objects in the quest to understand the Universe as a whole. Because the observations of the masses of galaxy clusters are directly sensitive to the properties of gravity, they provide crucial information. Other techniques such as observations of supernovas or the distribution of galaxies measure cosmic distances, which depend only on the expansion rate of the universe. In contrast, the cluster technique used by Rapetti and his colleagues measure in addition the growth rate of the cosmic structure, as driven by gravity.

"Cosmic acceleration represents a great challenge to our modern understanding of physics," said Rapetti's co-author Adam Mantz of NASA's Goddard Space Flight Center in Maryland. "Measurements of acceleration have highlighted how little we know about gravity at cosmic scales, but we're now starting to push back our ignorance."

The paper by Fabian Schmidt was published in Physics Review D, Volume 80 in October 2009 and is co-authored by Alexey Vikhlinin of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and Wayne Hu of the University of Chicago, Illinois. The paper by David Rapetti was recently accepted for publication in the Monthly Notices of the Royal Astronomical Society and is co- authored by Mantz, Steve Allen of KIPAC at Stanford and Harald Ebeling of the Institute for Astronomy in Hawaii.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.