March 2011

NASA Radar Image Shows Topography of Sendai

The topography surrounding Sendai, Japan is clearly visible in this combined radar image and topographic view generated with data from NASA's Shuttle Radar Topography Mission (SRTM) acquired in 2000. On March 11, 2011, a magnitude 8.9 earthquake struck offshore about 130 kilometers (80 miles) east of Sendai, the capital city of Japan's Miyagi Prefecture, generating a tsunami that devastated the low-lying coastal city of about 1 million residents.

The city is centered in the image and lies along the coastal plain between the Ohu Mountains and the Pacific Ocean. The eastern part of the city is a low-lying plains area, while the city center is hilly (the city's official elevation is about 43 meters, or 141 feet). Sendai's western areas are mountainous, with its highest point being Mt. Funagata at an elevation of about 1,500 meters (4,921 feet) above sea level.

According to the U.S. Geological Survey, the earthquake occurred as a result of thrust faulting on or near the subduction zone interface plate boundary between the Pacific and North America plates. At the latitude of this earthquake, the Pacific plate moves approximately westwards with respect to the North America plate at a velocity of 83 millimeters (3.3 inches) per year. The Pacific plate thrusts underneath Japan at the Japan Trench, and dips to the west beneath Eurasia. The location, depth and focal mechanism of the March 11 earthquake are consistent with the event having occurred as thrust faulting associated with subduction along this plate boundary.

This image combines a radar image acquired in February 2000 during the SRTM mission, and color-coding by topographic height using data from the same mission. Dark green colors indicate low elevations, rising through yellow and tan, to white at the highest elevations.

The Shuttle Radar Topography Mission is a cooperative project between NASA, the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Science Mission Directorate, Washington, D.C.

NASA's versatile Mars Reconnaissance Orbiter, which began orbiting Mars five years ago on March 10, has radically expanded our knowledge of the Red Planet and is now working overtime.

The mission has provided copious information about ancient environments, ice-age-scale climate cycles and present-day changes on Mars.

The orbiter observes Mars' surface, subsurface and atmosphere in unprecedented detail. The spacecraft's large solar panels and dish antenna have enabled it to transmit more data to Earth -- 131 terabits and counting, including more than 70,000 images than all other interplanetary missions combined. Yet many things had to go well for the mission to achieve these milestones.

True Gullies on MarsAfter a seven-month journey from Earth, the spacecraft fired its six main engines for nearly 27 minutes as it approached Mars on March 10, 2006. Mars could not capture it into orbit without this critically timed maneuver to slow the spacecraft. The orbiter's intended path took it behind Mars, out of communication, during most of the engine burn.

"That was tense, waiting until the spacecraft came back out from behind Mars and we had contact," recalled Dan Johnston, now the mission's deputy project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The Mars Reconnaissance Orbiter mission met all its science goals in a two-year primary science phase. Two extensions, the latest beginning in 2010, have added to the bounty of science returns.

The mission has illuminated three very different periods of Mars history. Its observations of the heavily cratered terrains of Mars, the oldest on the planet, show that different types of ancient watery environments formed water-related minerals. Some of these would have been more favorable for life than others.

In more recent times, water appears to have cycled as a gas between polar ice deposits and lower-latitude deposits of ice and snow. Extensive layering in ice or rock probably took hundreds of thousands to millions of years to form and, like ice ages on Earth, is linked to cyclic changes in the tilt of the planet's rotation axis and the changing intensity of sunlight near the poles.

The present climate is also dynamic, with volatile carbon dioxide and, just possibly, summertime liquid water modifying gullies and forming new streaks. With observations of new craters, avalanches and dust storms, the orbiter has shown a partially frozen world, but not frozen in time, as change continues today.

In addition to its science observations, the mission provides support for other spacecraft as they land and operate on the surface. The orbiter's cameras captured the Phoenix Mars Lander as it parachuted to the surface in 2008 and monitored the atmosphere for dust storms that would affect Phoenix and the Mars Exploration Rovers Spirit and Opportunity. The Mars Reconnaissance Orbiter augmented NASA's Mars Odyssey in performing relay functions for these missions.

JPL's Phil Varghese, project manager for the Mars Reconnaissance Orbiter, said, "The spacecraft is still in excellent health. After five years at Mars, it continues with dual capabilities for conducting science observations, monitoring the Mars environment and serving as a relay."

The orbiter has examined potential landing sites for NASA's Mars Science Laboratory mission, which will land a rover named Curiosity at one of those sites in August 2012. "We are preparing to support the arrival of the Mars Science Laboratory and the rover's surface operations," Varghese said. "In the meantime, we will extend the science observations into a third Martian year." One Mars year lasts nearly two Earth years.

The orbiter's Mars Color Imager has produced more than four Earth years of daily global weather maps. More than 18,500 images from the High Resolution Imaging Science Experiment camera have resolved features as small as a desk in target areas scattered around the planet that, combined, cover about as much ground as Alaska. More than 36,900 images from the Context Camera cover nearly two-thirds of the surface of Mars at a resolution that allows detection of features the size of large buildings.

The Compact Reconnaissance Spectrometer for Mars has mapped minerals on more than three-fourths of the planet's surface. The Mars Climate Sounder has monitored atmospheric temperature and aerosols with more than 59 million soundings. The Shallow Radar has checked for underground layers in more than 8,600 swaths of ground-penetrating observations.

"Each Mars year is unique, and additional coverage gives us a better chance to understand the nature of changes in the atmosphere and on the surface," said JPL's Rich Zurek, project scientist for the Mars Reconnaissance Orbiter. "We have already learned that Mars is a more dynamic and diverse planet than what we knew five years ago. We continue to see new things."

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate in Washington. Lockheed Martin Space Systems, Denver, built the orbiter and partners with JPL in spacecraft operations. For more about the Mars Reconnaissance Orbiter.

Pointing a Finger at Star Formation

NASA's Wide-field Infrared Survey Explorer, or WISE, captured this image of a star-forming cloud of dust and gas, called Sh2-284, located in the constellation of Monoceros. Lining up along the edges of a cosmic hole are several "elephant trunks" -- or monstrous pillars of dense gas and dust.

The most famous examples of elephant trunks are the "Pillars of Creation" found in an iconic image of the Eagle nebula from NASA's Hubble Space Telescope. In this WISE image, the trunks are seen as small columns of gas stretching toward the center of the void in Sh2-284, The most notable one can be seen on the right side at about the 3 o'clock position. It appears as a closed hand with a finger pointing toward the center of the void. That elephant trunk is about 7 light-years long.

Deep inside Sh2-284 resides an open star cluster, called Dolidze 25, which is emitting vast amounts of radiation in all directions, along with stellar winds. These stellar winds and radiation are clearing out a cavern inside the surrounding gas and dust, creating the void seen in the center. The bright green wall surrounding the cavern shows how far out the gas has been eroded. However, some sections of the original gas cloud were much denser than others, and they were able to resist the erosive power of the radiation and stellar winds. These pockets of dense gas remained and protected the gas "downwind" from them, leaving behind the elephant trunks.

Sh2-284 is relatively isolated at the very end of an outer spiral arm of our Milky Way galaxy. In the night sky, it's located in the opposite direction from the center of the Milky Way.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages and operates the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

The storm is subsiding now, but it could start up again in response to ongoing high-speed solar wind.

Poker Flat, AlaskaA solar wind stream hit Earth's magnetic field during the early hours of March 1st. The impact sparked a polar geomagnetic storm that was, at first, minor, but the storm has been intensifying throughout the day. Spotters are now reporting auroras over Northern Ireland, Latvia, Norway, and Sweden. If the trend continues, high-latitude sky watchers will likely witness bright auroras after nightfall on March 1-2. Northern-tier US states such as Maine, Wisconsin, Minnesota, and Washington could be favored with photographic and/or visual displays.

MKRdezign

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