Fires in North Korea

Multiple fires burned in North Korea in mid-October 2009, sending a plume of smoke over the Sea of Japan. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this true-color image on October 15. Red outlines indicate hotspots associated with active fires, although not all the fires have visible hotspots. The smoke plumes blow uniformly eastward, some of the individual plumes coalescing into a single large plume over the sea.

Robot Armada Might Scale New Worlds

An armada of robots may one day fly above the mountain tops of Saturn's moon Titan, cross its vast dunes and sail in its liquid lakes.

Wolfgang Fink, visiting associate in physics at the California Institute of Technology in Pasadena says we are on the brink of a great paradigm shift in planetary exploration, and the next round of robotic explorers will be nothing like what we see today.

"The way we explore tomorrow will be unlike any cup of tea we've ever tasted," said Fink, who was recently appointed as the Edward and Maria Keonjian Distinguished Professor in Microelectronics at the University of Arizona, Tucson. "We are departing from traditional approaches of a single robotic spacecraft with no redundancy that is Earth-commanded to one that allows for having multiple, expendable low-cost robots that can command themselves or other robots at various locations at the same time."

Fink and his team members at Caltech, the U.S. Geological Survey and the University of Arizona are developing autonomous software and have built a robotic test bed that can mimic a field geologist or astronaut, capable of working independently and as part of a larger team. This software will allow a robot to think on its own, identify problems and possible hazards, determine areas of interest and prioritize targets for a close-up look.

The way things work now, engineers command a rover or spacecraft to carry out certain tasks and then wait for them to be executed. They have little or no flexibility in changing their game plan as events unfold; for example, to image a landslide or cryovolcanic eruption as it happens, or investigate a methane outgassing event.

"In the future, multiple robots will be in the driver's seat," Fink said. These robots would share information in almost real time. This type of exploration may one day be used on a mission to Titan, Mars and other planetary bodies. Current proposals for Titan would use an orbiter, an air balloon and rovers or lake landers.

In this mission scenario, an orbiter would circle Titan with a global view of the moon, with an air balloon or airship floating overhead to provide a birds-eye view of mountain ranges, lakes and canyons. On the ground, a rover or lake lander would explore the moon's nooks and crannies. The orbiter would "speak" directly to the air balloon and command it to fly over a certain region for a closer look. This aerial balloon would be in contact with several small rovers on the ground and command them to move to areas identified from overhead.

"This type of exploration is referred to as tier-scalable reconnaissance," said Fink. "It's sort of like commanding a small army of robots operating in space, in the air and on the ground simultaneously."

A rover might report that it's seeing smooth rocks in the local vicinity, while the airship or orbiter could confirm that indeed the rover is in a dry riverbed - unlike current missions, which focus only on a global view from far above but can't provide information on a local scale to tell the rover that indeed it is sitting in the middle of dry riverbed.

A current example of this type of exploration can best be seen at Mars with the communications relay between the rovers and orbiting spacecraft like the Mars Reconnaissance Orbiter. However, that information is just relayed and not shared amongst the spacecraft or used to directly control them.

"We are basically heading toward making robots that command other robots," said Fink, who is director of Caltech's Visual and Autonomous Exploration Systems Research Laboratory, where this work has taken place.

"One day an entire fleet of robots will be autonomously commanded at once. This armada of robots will be our eyes, ears, arms and legs in space, in the air, and on the ground, capable of responding to their environment without us, to explore and embrace the unknown," he added.

Papers describing this new exploration are published in the journal "Computer Methods and Programs in Biomedicine" and in the Proceedings of the SPIE.

NASA Researchers Explore Lightning's NOx-ious Impact on Pollution, Climate

Every year, scientists learn something new about the inner workings of lightning.

With satellites, they have discovered that more than 1.2 billion lightning flashes occur around the world every year. (Rwanda has the most flashes per square kilometer, while flashes are rare in polar regions.) Laboratory and field experiments have revealed that the core of some lightning bolts reaches 30,000 Kelvin (53,540 ºF), a temperature hot enough to instantly melt sand and break oxygen and nitrogen molecules into individual atoms.

And then there is this: each of those billion lightning flashes produces a puff of nitrogen oxide gas (NOx) that reacts with sunlight and other gases in the atmosphere to produce ozone. Near Earth’s surface, ozone can harm human and plant health; higher in the atmosphere, it is a potent greenhouse gas; and in the stratosphere, its blocks cancer-causing ultraviolet radiation.

In 1827, the German chemist Justin von Liebig first observed that lightning produced NOx—scientific shorthand for a gaseous mixture of nitrogen and oxygen that includes nitric oxide (NO) and nitrogen dioxide (NO2). Nearly two centuries later, the topic continues to attract the attention of scientists.

Fossil fuel combustion, microbes in the soil, lightning, and forest fires all produce NOx. Scientists think lightning's contribution to Earth's NOx budget—probably about 10 percent—is relatively small compared to fossil fuel emissions. Yet they haven't been sure whether global estimates of NOx produced by lightning are accurate.

"There's still a lot of uncertainty about how much NOx lightning produces," said Kenneth Pickering, an atmospheric scientist who studies lightning at NASA's Goddard Space Flight Center in Greenbelt, Md. "Indeed, even recent published estimates of lightning's global NOx production still vary by as much as a factor of four. We're trying to narrow that uncertainty in order to improve the accuracy of both global climate models and regional air quality models."

NASA Refines Asteroid Apophis' Path Toward Earth

Using updated information, NASA scientists have recalculated the path of a large asteroid. The refined path indicates a significantly reduced likelihood of a hazardous encounter with Earth in 2036.

The Apophis asteroid is approximately the size of two-and-a-half football fields. The new data were documented by near-Earth object scientists Steve Chesley and Paul Chodas at NASA's Jet Propulsion Laboratory in Pasadena, Calif. They will present their updated findings at a meeting of the American Astronomical Society's Division for Planetary Sciences in Puerto Rico on Oct. 8.

"Apophis has been one of those celestial bodies that has captured the public's interest since it was discovered in 2004," said Chesley. "Updated computational techniques and newly available data indicate the probability of an Earth encounter on April 13, 2036, for Apophis has dropped from one-in-45,000 to about four-in-a million."

A majority of the data that enabled the updated orbit of Apophis came from observations Dave Tholen and collaborators at the University of Hawaii's Institute for Astronomy in Manoa made. Tholen pored over hundreds of previously unreleased images of the night sky made with the University of Hawaii's 2.2-meter (88-inch) telescope, located near the summit of Mauna Kea.

Tholen made improved measurements of the asteroid's position in the images, enabling him to provide Chesley and Chodas with new data sets more precise than previous measures for Apophis. Measurements from the Steward Observatory's 2.3 meter (90-inch) Bok telescope on Kitt Peak in Arizona and the Arecibo Observatory on the island of Puerto Rico also were used in Chesley's calculations.

The information provided a more accurate glimpse of Apophis' orbit well into the latter part of this century. Among the findings is another close encounter by the asteroid with Earth in 2068 with chance of impact currently at approximately three-in-a-million. As with earlier orbital estimates where Earth impacts in 2029 and 2036 could not initially be ruled out due to the need for additional data, it is expected that the 2068 encounter will diminish in probability as more information about Apophis is acquired.

Initially, Apophis was thought to have a 2.7 percent chance of impacting Earth in 2029. Additional observations of the asteroid ruled out any possibility of an impact in 2029. However, the asteroid is expected to make a record-setting -- but harmless -- close approach to Earth on Friday, April 13, 2029, when it comes no closer than 29,450 kilometers (18,300 miles) above Earth's surface.

"The refined orbital determination further reinforces that Apophis is an asteroid we can look to as an opportunity for exciting science and not something that should be feared," said Don Yeomans, manager of the Near-Earth Object Program Office at JPL. "The public can follow along as we continue to study Apophis and other near-Earth objects by visiting us on our AsteroidWatch Web site and by following us on the @AsteroidWatch Twitter feed."

The science of predicting asteroid orbits is based on a physical model of the solar system which includes the gravitational influence of the sun, moon, other planets and the three largest asteroids.

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

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. Cornell University, Ithaca, N.Y., operates the Arecibo Observatory under a cooperative agreement with the National Science Foundation in Arlington, Va.

Google Earth Application Maps Carbon's Course

Sometimes a picture really is worth a thousand words, particularly when the picture is used to illustrate science. Technology is giving us better pictures every day, and one of them is helping a NASA-funded scientist and her team to explain the behavior of a greenhouse gas.

Google Earth -- the digital globe on which computer users can fly around the planet and zoom in on key features -- is attracting attention in scientific communities and aiding public communication about carbon dioxide. Recently Google held a contest to present scientific results using KML, a data format used by Google Earth.

"I tried to think of a complex data set that would have public relevance," said Tyler Erickson, a geospatial researcher at the Michigan Tech Research Institute in Ann Arbor.

He chose to work with data from NASA-funded researcher Anna Michalak of the University of Michigan, Ann Arbor, who develops complex computer models to trace carbon dioxide back in time to where it enters and leaves the atmosphere.

"The datasets have three spatial dimensions and a temporal dimension," Erickson said. "Because the data is constantly changing in time makes it particularly difficult to visualize and analyze."

A better understanding of the carbon cycle has implications for energy and environmental policy and carbon management. In June 2009, Michalak described this research at the NASA Earth System Science at 20 symposium in Washington, D.C.

A snapshot from Erickson's Google Earth application shows green tracks representing carbon dioxide in the lowest part of the atmosphere close to Earth's surface where vegetation and land processes can impact the carbon cycle. Red tracks indicate particles at higher altitudes that are immune from ground influences.

The application is designed to educate the public and even scientists about how carbon dioxide emissions can be traced. A network of 1,000-foot towers across the United States is equipped with instruments by NOAA to measure the carbon dioxide content of parcels of air at single locations.

The application is designed to educate the public and even scientists about how carbon dioxide emissions can be traced. A network of 1,000-foot towers across the United States, like the tower above, are equipped with instruments by NOAA to measure the carbon dioxide content of parcels of air at single locations.

But where did that gas come from and how did it change along its journey? To find out, scientists rely on a sleuthing technique called "inverse modeling" – measuring gas concentrations at a single geographic point and then using clues from weather and atmospheric models to deduce where it came from. The technique is complex and difficult to explain even to fellow scientists.

Michalak related the technique to cream in a cup of coffee. "Say someone gave you a cup of creamy coffee," Michalak said. "How do you know when that cream was added?" Just as cream is not necessarily mixed perfectly, neither is the carbon dioxide in the atmosphere. If you can see the streaks of cream (carbon dioxide) and understand how the coffee (atmosphere) was stirred (weather), then scientists can use those clues to retrace the time and location that the ingredient was added to the mix.

The visual result typically used by scientists is a static two-dimensional map of the location of the gas, as averaged over the course of a month. Most carbon scientists know how to interpret the 2D map, but visualizing the 3D changes for non-specialists has proved elusive. Erickson spent 70 hours programming the Google Earth application that makes it easy to navigate though time and watch gas particles snake their way toward the NOAA observation towers. For his work, Erickson was declared one of Google's winners in March 2009.

"Having this visual tool allows us to better explain the scientific process," Michalak said. "It's a much more human way of looking at the science."

The next step, Erickson said, is to adapt the application to fit the needs of the research community. Scientists could use the program to better visualize the output of complex atmospheric models and then improve those models so that they better represent reality.

"Encouraging more people to deliver data in an interactive format is a good trend," Erickson said. "It should help innovation in research by reducing barriers to sharing data."

Galileo's Jupiter Journey Began Two Decades Ago

• Launch: Oct. 18, 1989, from Kennedy Space Center, Fla., on space shuttle Atlantis on mission STS-34


• Arrival in orbit around Jupiter: Dec. 7, 1995


• VEEGA (Venus-Earth-Earth Gravity Assist) is the acronym mission planners gave for Galileo's flight path through the inner solar system


• Observed impacts of fragments from comet Shoemaker-Levy 9 into Jupiter


• Approximate number of people (from around the world) who worked on the Galileo mission: 800


• More than 100 scientists from United States, Great Britain, Germany, France, Canada and Sweden carried out Galileo's experiments

PASADENA, Calif. - NASA's Galileo spacecraft began what would become a 14-year odyssey of exploration 20 years ago this Sunday, Oct. 18. Galileo was humanity's first emissary to orbit a planet in the outer solar system - Jupiter.

Galileo was launched into space aboard the space shuttle Atlantis on Oct. 18, 1989, from Kennedy Space Center, Florida. The crew of Atlantis deployed Galileo out of the shuttle's cargo bay only hours after launch. Then, a little over seven hours after leaving Earth, Galileo was propelled onto its interplanetary flight path by a two-stage, solid-fuel motor called an Inertial Upper Stage. Although earlier plans called for Galileo to use a more powerful upper stage so that it could fly directly to Jupiter, the final flight took it by other planets first so that it could gain energy from the gravity of each. Galileo flew past Venus on Feb. 10, 1990, and then twice past Earth -- once on Dec. 8, 1990, and again on Dec. 8, 1992.

Even before its arrival at Jupiter in 1995, Galileo was making groundbreaking discoveries. On Oct. 29, 1991, the spacecraft flew past asteroid Gaspra - sending back the first close up images of one of these celestial wanderers. Then on Aug. 28, 1993, Galileo encountered the 15.2-kilometer-wide (9.4-mile) asteroid Ida, where it took the first images of an asteroid and discovered the first asteroid moon, the 1.6-kilometer-wide (1-mile) Dactyl. During the latter part of its interplanetary cruise, Galileo was used to observe the collisions of fragments of Comet Shoemaker-Levy with Jupiter in July 1994.

Galileo arrived at Jupiter on Dec. 7, 1995, entering orbit and dropping a probe into the giant planet's atmosphere. The probe's velocity as it entered Jupiter's atmosphere was a blistering 47.6 kilometers per second (106,500 miles per hour). After the atmospheric drag and a deployed parachute slowed its descent rate, the probe relayed to Galileo the first in-place studies of Jupiter's clouds and winds, furthering scientists' understanding of how the gas giant evolved. The probe also made composition measurements designed to assess the degree of evolution of Jupiter compared to the sun.

While the descent of the probe was a highlight of Galileo's mission, it was hardly the only one. Galileo extensively investigated the geologic diversity of Jupiter's four largest moons: Ganymede, Callisto, Io and Europa. It found that Io's extensive volcanic activity is 100 times greater than that found on Earth. Galileo discovered strong evidence that Jupiter's moon Europa has a melted saltwater ocean under an ice layer on its surface. Scientists estimate such an ocean could be up to 100 kilometers (62 miles) deep underneath its frozen surface and contain about twice as much water as all of Earth's oceans. Data showed moons Ganymede and Callisto may also have a liquid-saltwater layer. The biggest discovery surrounding Ganymede was the presence of a magnetic field. No other moon of any planet is known to have one.

When Galileo turned its instruments towards the giant gas world itself, the spacecraft made the first observations of ammonia clouds in another planet's atmosphere. It also observed numerous thunderstorms on Jupiter many times larger than those on Earth, with lightning strikes up to 1,000 times more powerful than on Earth. It was the first spacecraft to dwell in a giant planet's magnetosphere long enough to identify its global structure and to investigate the dynamics of Jupiter's magnetic field. Galileo determined that Jupiter's ring system is formed by dust kicked up as interplanetary meteoroids smash into the planet's four small inner moons. Galileo data showed that Jupiter's outermost ring is actually two rings, one embedded within the other.

Having traveled approximately 4.6 billion kilometers (about 2.8 billion miles), the hardy spacecraft endured more than four times the cumulative dose of harmful Jovian radiation it was designed to withstand -- and still major systems functioned. But while it was still enjoying relatively good health, the spacecraft's propellant was low. Without propellant, Galileo would not be able to point its antenna toward Earth or adjust its trajectory, so controlling the spacecraft would no longer be possible. Mission managers at NASA and JPL decided to place their resilient Jovian explorer on a collision course with Jupiter to eliminate any chance of an unwanted impact between the spacecraft and Europa. The possibility of life existing on Europa is so compelling and has raised so many unanswered questions that it is prompting plans for future spacecraft to return to the icy moon.

The Galileo spacecraft's 14-year odyssey came to an end on Sunday, Sept. 21, 2003, when the spacecraft passed into Jupiter's shadow, then disintegrated in the planet's dense atmosphere at 11:57 a.m. Pacific Daylight Time. Its entry speed was 48.2 kilometers per second (nearly 108,000 miles per hour). That is the equivalent of traveling from Los Angeles to New York City in 82 seconds.

JPL's Deep Space Network tracking station in Goldstone, Calif., received the last signal at 12:43:14 PDT, 46 minutes after it was sent. The delay is due to the time it takes for the signal to travel to Earth. Hundreds of former Galileo project members and their families were present at JPL for a celebration to bid the spacecraft goodbye.

Galileo project scientist Torrence Johnson said at the time, "We haven't lost a spacecraft, we've gained a steppingstone into the future of space exploration."

JPL, a division of the California Institute of Technology in Pasadena, managed the Galileo mission for NASA. JPL designed and built the Galileo orbiter, and operated the mission.

Team Runs Operational Test to Prepare for Extracting Spirit

Engineers using test rovers on Earth to prepare for extracting the sand-trapped Spirit rover on Mars have added a new challenge to their preparations.

Until last week, the engineers commanding and assessing drives by the test rovers were usually in the same room as the sandbox setup simulating Spirit's predicament, where they can watch how each test goes. That changed for the latest preparation, called an operational readiness test.

The team members commanding drives by a test rover last week stayed away from the building with the sandbox. They assessed the results of each commanded drive only from the images and other data communicated from the test rover, the same way the team does for daily operations of the rovers that are on Mars.

"We conducted this round of testing under more flight-like conditions to test the team's ability to make very complex extraction driving decisions using only the data sent back from the rover," said Mars Exploration Rover Project Manager John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The test began on Oct. 12 and ran five days on an accelerated schedule of two Martian days' worth of commanding every day. The rover team also operated both Spirit and its twin, Opportunity, while conducting this readiness test at JPL.

Spirit became embedded in soft soil at a site called "Troy" five months ago, more than five years into a mission on Mars that was originally scheduled to last for three months. The rover team suspended further driving attempts with Spirit while evaluating possibilities from tests performed at JPL simulating the Troy situation.

Current plans call for an independent panel to review Spirit driving plans in late October, following analysis of results from the readiness test. Unless that review recommends any further preparations, Spirit will probably begin extraction moves within two weeks after the review.

Spirit has spent much of its time at Troy actively examining its surroundings, including analysis of layered soil at the site. In September, a new issue began affecting operations. Data from Spirit indicated that a brake on the motor that rotates the rover's dish-shaped high-gain antenna was not working correctly. The team has been getting more diagnostic data and developing a work-around strategy similar to work-arounds already used for rover-motor brakes that showed similar symptoms earlier.

NASA Celebrates Earth Science Week

Every day at NASA scientists study changes on our home planet, and a significant portion of that study focuses on changes in our oceans. To showcase some of that research, NASA is releasing six short videos in commemoration of Earth Science Week 2009. The videos highlight the connection between climate change and our oceans.

The theme of Earth Science Week (October 11 through 17) this year is "Understanding Climate." The six NASA videos complete a series called "Tides of Change," which all focus on the ocean-climate connection. Each video features a specific component of the connection, such as marine life or the water cycle.

Another highlight of NASA's Earth Science Week contributions is a live educational webcast on October 14 at 1 p.m., EDT. Classrooms around the country will participate in this live event that focuses on Earth science discoveries and careers. Two oceanographers will discuss their careers, illustrate NASA’s unique, space-based view of the oceans and answer participant questions. Watch the webcast here.

Also part of NASA's offerings, the agency's Global Climate Change Web site will feature these videos and a 3D interactive, "Eyes on Earth." The downloadable Eyes on Earth application allows users to observe the paths of satellites that study our planet, learn about related missions and more.

Earth Science Week, organized by the American Geological Institute, encourages people everywhere to explore our planet and learn about geoscience fields.

Though Earth Science Week 2009 only lasts through October 17, At NASA every week is Earth science week, as scientists continue to learn about our changing planet and what drives those changes. A world of Earth science exploration is all at your fingertips and on-line from NASA's Earth Web site any day of the week.

Cassini Data Help Redraw Shape of Solar System

Images from the Ion and Neutral Camera on NASA's Cassini spacecraft suggest that the heliosphere, the region of the sun's influence, may not have the comet-like shape predicted by existing models. In a paper published Oct. 15 in Science Express, researchers from the Johns Hopkins Applied Physics Laboratory present a new view of the heliosphere, and the forces that shape it.

"These images have revolutionized what we thought we knew for the past 50 years; the sun travels through the galaxy not like a comet but more like a big, round bubble," said Stamatios Krimigis of the Applied Physics Lab, in Laurel, Md., principal investigator for Cassini's Magnetospheric Imaging Instrument which carries the Ion and Neutral Camera. "It's amazing how a single new observation can change an entire concept that most scientists had taken as true for nearly fifty years."

As the solar wind flows from the sun, it carves out a bubble in the interstellar medium. Models of the boundary region between the heliosphere and interstellar medium have been based on the assumption that the relative flow of the interstellar medium and its collision with the solar wind dominate the interaction. This would create a foreshortened "nose" in the direction of the solar system's motion, and an elongated "tail" in the opposite direction.

The Ion and Neutral Camera images suggest that the solar wind's interaction with the interstellar medium is instead more significantly controlled by particle pressure and magnetic field energy density.

"The map we've created from the images suggests that pressure from a hot population of charged particles and interaction with the interstellar medium's magnetic field strongly influence the shape of the heliosphere," says Don Mitchell, Magnetospheric Imaging Instrument/Ion and Neutral Camera co-investigator at the Applied Physics Lab.

Since entering into orbit around Saturn in July of 2004, the Ion and Neutral Camera has been mapping energetic neutral atoms near the planet, as well as their dispersal across the entire sky. The energetic neutral atoms are produced by energetic protons, which are responsible for the outward pressure of the heliosphere beyond the interface where the solar wind collides with the interstellar medium, and which interact with the magnetic field of the interstellar medium.

"Energetic neutral atom imaging has demonstrated its power to reveal the distribution of energetic ions, first in Earth's own magnetosphere, next in the giant magnetosphere of Saturn and now throughout vast structures in space-out to the very edge of our sun's interaction with the interstellar medium," says Edmond C. Roelof, Magnetospheric Imaging Instrument co-investigator at the Applied Physics Lab.

The results from Cassini complement and extend findings from NASA's Interstellar Boundary Explorer, or IBEX, spacecraft. Data from IBEX and Cassini have made it possible for scientists to construct the first comprehensive sky map of our solar system and its location in the Milky Way galaxy.

NASA Celebrates Earth Science Week

During the week of October 11-17, the world will be celebrating Earth Science Week and NASA has a major part in that celebration. NASA studies a variety of topics on Earth science, from climate change to hurricanes.

Every day at NASA, satellites, computer models and scientists study the changing Earth including dust plumes off the coast of Africa, pollution, the ozone hole, global temperatures, oceans, atmosphere, global ice and snow, weather and much more. Engineers and technicians conceive, design and build new instruments and satellites to investigate different aspects of the Earth. NASA is committed to a better understanding of our Earth to improve our knowledge and our lives.

Earth Science Week 2009 provides a focus on what NASA does 24 hours a day, seven days a week. It encourages people everywhere to explore the natural world and learn about the geosciences. "Understanding Climate," the theme of Earth Science Week 2009, will promote scientific understanding of Earth’s climate. As a leader in climate study, this year NASA's contribution to Earth Science Week will focus on the connection between climate change and our oceans.

NASA is releasing a series of five short educational videos each day during Earth Science Week under the theme "Understanding Climate." This year's theme was selected by the American Geological Institute (AGI). The NASA video series entitled "Tides of Change" will focus on the ocean-climate connection. Each video will feature a specific aspect of this connection, such as the water cycle or life in the ocean. The videos can be seen at: http://climate.nasa.gov/esw/videoseries/.

NASA’s Global Climate Change website, located at: http://climate.nasa.gov/esw/ will feature these videos as part of the interactive 3-D Eyes on Earth. This application allows users to fly around the planet on the wings of a satellite, observing the planet’s vital signs from space. Climate.nasa.gov will also be a one-stop shop during ESW09 for all of NASA’s best Earth science education resources related to the understanding of climate.

One of the NASA Earth Science Week highlights is a live educational webcast on Oct. 14 at 1:00 p.m. EDT. Classrooms around the country will participate in this live event focused on Earth science discoveries and careers. Two oceanographers will discuss their careers, illustrate NASA’s unique view of the oceans from space, and answer questions submitted by participants. To see the webcast: http://www.ustream.tv/channel/earth-science-week-webcast.

NASA has contributed a selection of materials to the Earth Science Week 2009 Kits, which are distributed to 16,000 educators. Materials include a Hurricane Katrina activity, NASA Dynamic Earth DVD, and MyNASAData activity. NASA hosted a pre-ESW09 training session for educators on September 30 through its Digital Learning Network and the Central Operation of Resources for Educators (CORE). Participants included educators from NASA Educator Resource Centers, the Aerospace Education Services Program, NASA Explorer Schools, Educator Astronauts, and K-12 teachers from across the United States.

At NASA every week is Earth science week as scientists continue to learn about our changing planet and what drives those changes. A world of Earth science exploration is all at your fingertips and on-line at www.nasa.gov any day of the week, not just Earth Science Week.

NASA Refines Asteroid Apophis' Path Toward Earth

Using updated information, NASA scientists have recalculated the path of a large asteroid. The refined path indicates a significantly reduced likelihood of a hazardous encounter with Earth in 2036.

The Apophis asteroid is approximately the size of two-and-a-half football fields. The new data were documented by near-Earth object scientists Steve Chesley and Paul Chodas at NASA's Jet Propulsion Laboratory in Pasadena, Calif. They will present their updated findings at a meeting of the American Astronomical Society's Division for Planetary Sciences in Puerto Rico on Oct. 8.

"Apophis has been one of those celestial bodies that has captured the public's interest since it was discovered in 2004," said Chesley. "Updated computational techniques and newly available data indicate the probability of an Earth encounter on April 13, 2036, for Apophis has dropped from one-in-45,000 to about four-in-a million."

A majority of the data that enabled the updated orbit of Apophis came from observations Dave Tholen and collaborators at the University of Hawaii's Institute for Astronomy in Manoa made. Tholen pored over hundreds of previously unreleased images of the night sky made with the University of Hawaii's 2.2-meter (88-inch) telescope, located near the summit of Mauna Kea.

Tholen made improved measurements of the asteroid's position in the images, enabling him to provide Chesley and Chodas with new data sets more precise than previous measures for Apophis. Measurements from the Steward Observatory's 2.3 meter (90-inch) Bok telescope on Kitt Peak in Arizona and the Arecibo Observatory on the island of Puerto Rico also were used in Chesley's calculations.

The information provided a more accurate glimpse of Apophis' orbit well into the latter part of this century. Among the findings is another close encounter by the asteroid with Earth in 2068 with chance of impact currently at approximately three-in-a-million. As with earlier orbital estimates where Earth impacts in 2029 and 2036 could not initially be ruled out due to the need for additional data, it is expected that the 2068 encounter will diminish in probability as more information about Apophis is acquired.

Initially, Apophis was thought to have a 2.7 percent chance of impacting Earth in 2029. Additional observations of the asteroid ruled out any possibility of an impact in 2029. However, the asteroid is expected to make a record-setting -- but harmless -- close approach to Earth on Friday, April 13, 2029, when it comes no closer than 29,450 kilometers (18,300 miles) above Earth's surface.

"The refined orbital determination further reinforces that Apophis is an asteroid we can look to as an opportunity for exciting science and not something that should be feared," said Don Yeomans, manager of the Near-Earth Object Program Office at JPL. "The public can follow along as we continue to study Apophis and other near-Earth objects by visiting us on our AsteroidWatch Web site and by following us on the @AsteroidWatch Twitter feed."

The science of predicting asteroid orbits is based on a physical model of the solar system which includes the gravitational influence of the sun, moon, other planets and the three largest asteroids.

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

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. Cornell University, Ithaca, N.Y., operates the Arecibo Observatory under a cooperative agreement with the National Science Foundation in Arlington, Va.

Space Radar Reveals Topography of Tsunami Site

Two color-coded perspective views of the Independent State of Samoa (left) and American Samoa (right), generated with digital elevation data from the Shuttle Radar Topography Mission, illustrate the varying topography of the islands. A tsunami generated by a major undersea earthquake on Sept. 29, 2009, inundated the more heavily populated southern coast of Tutuila, the largest of the islands of American Samoa, with an ocean surge more than 3 meters (10 feet) deep, causing scores of casualties. The tsunami also inundated villages on the southern coast of the Independent State of Samoa with an ocean surge perhaps more than 3 meters (10 feet) deep, and also impacted the more heavily populated northern coasts with a surge measured at nearly 1.5 meters (4 feet) at the capital city of Apia.

Digital topographic data such as those produced by SRTM can be used to aid researchers and planners in predicting which coastal regions are at the most risk from such waves, as well as from the more common storm surges caused by tropical storms and even sea level rise.

Arctic Sea Ice level is Third Lowest on Record

U.S. satellite measurements show Arctic sea ice extent in 2009 – the area of the Arctic Ocean covered by floating ice – was the third lowest since satellite measurements were first made in 1979. The ice area at minimum was an increase from the past two years, but still well below the average for the past 30 years.

Arctic sea ice reached its minimum extent around September 12, as shown in the image and video to the right. According to scientists affiliated with the National Snow and Ice Data Center (NSIDC), sea ice coverage dropped to 5.10 million square kilometers (1.97 million square miles) at its minimum. The ice cover was 970,000 square kilometers (370,000 square miles) greater than the record low of 2007 and 580,000 square kilometers (220,000 square miles) greater than 2008.

NSIDC is sponsored by several U.S. government agencies, including NASA. Ice data are derived from measurements made by U.S. Department of Defense and NASA satellites, with key work in interpreting the data and developing the 30-year history done by scientists at NASA's Goddard Space Flight Center in Greenbelt, Md.

"The changes from year to year are interesting since there has been large variability," said Josefino Comiso, a sea ice expert at NASA Goddard. "But we need to look at several years of data to examine the long-term trends."

"Our three decades of continuous satellite measurements show a rapid decline of about 11.6 percent per decade," Comiso said. Arctic sea ice has declined about 34 percent since measurements were first made in the late 1970s.

The four lowest ice extents on record have occurred between 2005 and 2009, with the record minimum reached during a dramatic drop in ice cover in 2007 that was exacerbated by unusual polar winds.

Several recent studies based on data from NASA’s ICESat and QuikScat satellites have shown that, in addition to shrinking geographic ice coverage, the amount of multi-year ice cover – thicker ice that survives more than one summer -- has been declining in recent years.

"The oceans are crucial to Earth's climate system, since they store huge amounts of heat," said Comiso. "Changes in sea ice cover can lead to circulation changes not just in the Arctic Ocean, but also in the Atlantic and Pacific oceans. If you change ocean circulation, you change the world's climate."

Changes in the Arctic ice cover could also mean a new paradigm for life in the sea. "The waters at high latitudes are some of the most biologically productive in the world because of the presence of sea ice," Comiso added. "Many of our richest fisheries are the seas around the Arctic Ocean, and we don't know what the consequences might be if the seasonal sea ice disappears in these regions."

Cassini Reveals New Ring Quirks, Shadows in Saturn Equinox

NASA scientists are marveling over the extent of ruffles and dust clouds revealed in the rings of Saturn during the planet's equinox last month. Scientists once thought the rings were almost completely flat, but new images reveal the heights of some newly discovered bumps in the rings are as high as the Rocky Mountains. NASA released the images Monday.

"It's like putting on 3-D glasses and seeing the third dimension for the first time," said Bob Pappalardo, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "This is among the most important events Cassini has shown us."

On Aug. 11, sunlight hit Saturn's rings exactly edge-on, performing a celestial magic trick that made them all but disappear. The spectacle occurs twice during each orbit Saturn makes around the sun, which takes approximately 10,759 Earth days, or about 29.7 Earth years. Earth experiences a similar equinox phenomenon twice a year; the autumnal equinox will occur Sept. 22, when the sun will shine directly over Earth's equator.

For about a week, scientists used the Cassini orbiter to look at puffy parts of Saturn's rings caught in white glare from the low-angle lighting. Scientists have known about vertical clumps sticking out of the rings in a handful of places, but they could not directly measure the height and breadth of the undulations and ridges until Saturn's equinox revealed their shadows.

"The biggest surprise was to see so many places of vertical relief above and below the otherwise paper-thin rings," said Linda Spilker, deputy project scientist at JPL. "To understand what we are seeing will take more time, but the images and data will help develop a more complete understanding of how old the rings might be and how they are evolving."

The chunks of ice that make up the main rings spread out 140,000 kilometers (85,000 miles) from the center of Saturn, but they had been thought to be only around 10 meters (30 feet) thick in the main rings, known as A, B, C, and D.

In the new images, particles seemed to pile up in vertical formations in each of the rings. Rippling corrugations -- previously seen by Cassini to extend approximately 804 kilometers (500 miles) in the innermost D ring -- appear to undulate out to a total of 17,000 kilometers (11,000 miles) through the neighboring C ring to the B ring.

The heights of some of the newly discovered bumps are comparable to the elevations of the Rocky Mountains. One ridge of icy ring particles, whipped up by the gravitational pull of Saturn's moon Daphnis as it travels through the plane of the rings, looms as high as about 4 kilometers (2.5 miles). It is the tallest vertical wall seen within the rings.

"We thought the plane of the rings was no taller than two stories of a modern-day building and instead we've come across walls more than 2 miles [3 kilometers] high," said Carolyn Porco, Cassini imaging team leader at the Space Science Institute in Boulder, Colo. "Isn't that the most outrageous thing you could imagine? It truly is like something out of science fiction."

Scientists also were intrigued by bright streaks in two different rings that appear to be clouds of dust kicked up in collisions between small space debris and ring particles. Understanding the rate and locations of impacts will help build better models of contamination and erosion in the rings and refine estimates of their age. The collision clouds were easier to see under the low-lighting conditions of equinox than under normal lighting conditions.

At the same time Cassini was snapping visible-light photographs of Saturn's rings, the Composite Infrared Spectrometer instrument was taking the rings' temperatures. During equinox, the rings cooled to the lowest temperature ever recorded. The A ring dropped down to a frosty 43 Kelvin (382 degrees below zero Fahrenheit). Studying ring temperatures at equinox will help scientists better understand the sizes and other characteristics of the ring particles.

The Cassini spacecraft has been observing Saturn, its moons and rings since it entered the planet's orbit in 2004. The spacecraft's instruments have discovered new rings and moons and have improved our understanding of Saturn's ring system.