Saturday, November 30, 2013

Aorounga Crater, Chad


This image from Japan’s ALOS satellite shows the Aorounga Crater in northern Chad.

The crater is just south of the Tibesti Mountains, a range of inactive – with some potentially active – volcanoes in the central Sahara desert.

Measuring about 12 km across, the crater was created by a meteorite impact about 340 million years ago.

Clearly visible is the dark, central peak, caused by material splashing up after the impact, similar to how water bounces back up when a stone is thrown in. This peak is surrounded by a low, sand-filled ring, which is surrounded by another ring of rock from when the material was thrown outwards. A distinctive low, sand-filled trough circles the others – the outer edges of the initial impact.

The linear rock ridges that run diagonally across this image are ‘yardangs’ and are formed by wind erosion. Here, we can clearly see how the wind blows from northeast to southwest. Sand dunes form in the wind-cut valleys between the rock ridges of the yardangs.

Japan’s Advanced Land Observation Satellite captured this image on 3 November 2010. ALOS was supported as a Third Party Mission, which means that ESA used its multimission ground systems to acquire, process, distribute and archive data from the satellite to its user community.

This image is featured on the Earth from Space video program.

Photo credit: JAXA/ESA

Friday, November 29, 2013

San Francisco Bay


An urban sprawl engulfs San Francisco Bay in a sea of lights. The three bridges Oakland Bay Bridge, San Mateo Bridge and Dumbarton Bridge light up as straight lines connecting the coasts. From top right going clockwise freeways pass through Oakland, Hayward, Fremont, San Jose, Palo Alto, Redwood City, San Mateo and San Francisco.

The bright lights of the cities are themselves surrounded by natural parks. Passed the coastal Eastern Bay Regional Parks to the right, the cities of Pleasanton and Walnut Creek keep the dark wilderness at bay with their street lighting. To the left, aside from the Half Moon Bay Airport on the coast, blackness prevails: the Pacific Ocean.

This image was taken on 23 December 2012 by an astronaut on the International Space Station. Circling Earth at an altitude of around 400 km astronauts witness the beauty of our planet from a unique vantage point. At night, human settlements can be seen as street lighting illuminates the sky. ESA developed an automatic camera tripod that compensates for the speed of the Space Station flying at 28 800 km/h to take sharper pictures at night.

Photo credit: ESA/NASA

Wednesday, November 27, 2013

Flooding in Sardinia


In mid-November 2013, extratropical cyclone Cleopatra brought devastating flooding to the Italian island of Sardinia that has claimed at least 18 lives and led to the declaration of a state of emergency for the island. To assist in the disaster response efforts, scientists at NASA's Jet Propulsion Laboratory, Pasadena, California, in collaboration with the Italian Space Agency and Università degli studi della Basilicata, generated this preliminary version of a flood proxy map for inundated regions in Sardinia.

Areas of strong blue on the map are regions that have likely experienced flooding. The blue color represents a decrease of radar signal echo on November 18, 2013 compared to data from October 17, 2013. The decreased radar signal echo is likely to have been caused by water covering land (water has a smooth surface, which results in a weaker echo signal, while land has a rough surface and stronger echo). Flat regions that are colored dark blue can be interpreted as likely flooded regions, but other areas need further analysis before interpreting. Some distortion in the geolocation of this preliminary product is present in areas of high relief.

The approximately 5 by 12 miles (8 by 20 kilometers) map covers the region marked by the red rectangular box in the larger, 137 mile (220 kilometer) long overview image of Sardinia shown above processed by JPL's Advanced Rapid Imaging and Analysis (ARIA) team using X-band interferometric synthetic aperture radar data from the Italian Space Agency's COSMO-SkyMed satellite constellation. The technique uses a prototype algorithm to rapidly detect surface changes caused by natural or human-produced damage. It was processed as part of a joint collaboration between JPL, Caltech, the Italian Space Agency (ASI) Centro Interpretazione Dati di Osservazione della Terra (CIDOT) and the Università degli studi della Basilicata. Image processing was implemented using the JPL Interometric Synthetic Aperture Radar Scientific Computing Environment (ISCE) software package, and the amplitude images were registered to the NASA Shuttle Radar Topography Mission Plus digital elevation model with a resolution of 1 arc second. Individual pixel size of the flood map is about 98 feet (30 meters) across.

Image credit: NASA/JPL-Caltech/ASI

Sunday, November 24, 2013

Wildfire Scars in New South Wales, Australia


October 2013 brought the worst fires seen in Australia's New South Wales in many decades. More than 100 wildfires burned. One of the largest was the Hall Road fire, southwest of Sydney, west of the town of Wollongong. The fire scar is seen in this satellite image acquired November 14, 2013, by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft. Vegetation is displayed in shades of red, burned areas are dark gray, water is black and blue, and urban areas are blue-gray. The image covers an area of 20 by 24 miles (33 by 39 kilometers), and is located at 34.3 degrees south latitude, 150.7 degrees east longitude.

Image credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Saturday, November 23, 2013

Qarhan Salt Lake, China


This false-color composite image from the Kompsat-2 satellite shows part of the Qarhan Salt Lake on the Tibetan Plateau in China.

There are multiple salt lakes across this region, but Qarhan’s 5850 sq km make it the largest. It holds an estimated 60 billion tonnes of salt, and is also a major production base for potassium and magnesium.

In this image, we can see division of the salt evaporation ponds. While the false color makes them appear blue, salt ponds naturally range in color depending on their algal concentration and salinity.

The nearest city, Golmud, sits about 50 km to the southwest (not pictured).

This image was acquired on 4 December 2008 by the Korea Aerospace Research Institute’s Kompsat-2.

ESA supports Kompsat as a Third Party Mission, meaning it uses its ground infrastructure and expertise to acquire, process and distribute data to users.

Photo credit: KARI/ESA

Thursday, November 21, 2013

Pine Island Glacier Iceberg by Proba-2


The smallest camera on one of ESA’s smallest satellites caught this image of a giant iceberg – larger than Singapore – drifting away from Antarctica’s Pine Island Glacier.

The espresso cup-sized Exploration Camera, X-Cam, on ESA’s Proba-2 satellite took this picture on 19 November, peering eastwards into the Antarctic interior.

The 700 sq km iceberg in open water to the right side of the image, officially known as iceberg B-31, broke away from the Pine Island Glacier on the Antarctic west coast back in July. Such a ‘calving’ was widely anticipated, with a crack in the ice having formed over several years.

The berg is gradually drifting away from its parent glacier, expected either to move east, parallel to the coast, or head out into the Southern Ocean.

Proba-2’s X-Cam’s black and white image gives a wider perspective than a standard Earth observation camera, more like an astronaut’s eye view, but it was taken at around double the altitude that human crews currently fly, at more than 700 km.

Less than a cubic meter in size, Proba-2 focuses on observing solar activity and space weather. But it also keeps a small eye on its home world.

One of the 17 experimental technologies hosted on Proba-2 is the compact X-Cam. Housed on the underside of the satellite, the monochrome X-Cam observes in the visible and infrared with a 100° field of view.

Photo credit: ESA

Note: For more information, see PIA17694: Pine Island Glacier, Antarctica, MISR Multi-angle Composite.

Wednesday, November 20, 2013

Tennessee River Near Chattanooga


In the fall of 1863, Confederate General Braxton Bragg's army occupied the mountains that ring the vital railroad center of Chattanooga, on the Tennessee River. Union General Ulysses Grant, brought in to save the situation, steadily built up offensive strength, and on November 23-25 burst the blockade in a series of brilliantly executed attacks. Union forces pushed Confederate troops away from Chattanooga. The victory set the stage for General Sherman's Atlanta Campaign. The image was acquired October 17, 2010, and is located at 35 degrees north latitude, 85.3 degrees west longitude.

Image credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Sunday, November 17, 2013

Dasht-e Lut Salt Desert


The Dasht-e Lut salt desert in southeast Iran is captured in this Envisat image.

The desert is often called the ‘hottest place on Earth’ as satellites measured record surface temperatures there for several years. The highest land surface temperature ever recorded was in the Lut Desert in 2005 at 70.7ºC, as measured by NASA’s Aqua satellite.

The light area in the center of the image are the long, parallel wind-carved ridges and furrows. The darker area to the east is an extent of massive sand dunes, some reaching up to 300 m tall.

In the upper-right section we can see a light green, shallow body of water that straddles Iran’s border with Afghanistan. With their arid surroundings, the wetlands in this border region have been a major source of food and fresh water for thousands of years, as well as an important stop for migratory birds. But irrigation expansion combined with droughts have caused the water levels in these wetlands to drop significantly – and some years even dry up.

In the lower-left we can see the white, snow-capped Jebal Barez mountains.

A major earthquake struck about 100 km east of the snow-caps in 2003, its epicenter near the ancient city of Bam (lower-central portion of image). Iran experiences frequent tectonic activity as several major fault lines cross the country.

This image was acquired by Envisat’s MERIS instrument on 2 April 2012 and is also featured on the Earth from Space video program.

Photo credit: ESA

Saturday, November 16, 2013

Chinese Fishing Vessels


Cities and street lights are not the only things visible from the International Space Station at night. This picture taken with the automated camera aid Nightpod shows Chinese fishing boats using bright lights on the South-China Sea to attract fish to their nets.

The village at the center is unidentified. The image was taken by an astronaut on Expedition 30 and the frame number is 172306.

Photo credit: ESA/NASA

Thursday, November 14, 2013

Damage to Tacloban City, Philippines by Typhoon Haiyan


When Super Typhoon Haiyan, one of the most powerful storms ever recorded on Earth, struck the Philippines November 8, 2013, it tore a wide swath of destruction across large parts of the island nation. To assist in the disaster response efforts, scientists at NASA's Jet Propulsion Laboratory, Pasadena, California, in collaboration with the Italian Space Agency, generated this image of the storm's hardest-hit regions, depicting its destruction.

The 40-by-50 kilometer damage proxy map, which covers a region near Tacloban City, where the massive storm made landfall, was processed by JPL's Advanced Rapid Imaging and Analysis (ARIA) team using X-band interferometric synthetic aperture radar data from the Italian Space Agency's COSMO-SkyMed satellite constellation. The technique uses a prototype algorithm to rapidly detect surface changes caused by natural or human-produced damage. The assessment technique is most sensitive to destruction of the built environment. When the radar images areas with little to no destruction, its image pixels are transparent. Increased opacity of the radar image pixels reflects damage, with areas in red reflecting the heaviest damage to cities and towns in the storm's path. The time span of the data for the change is August 19--November 11, 2013. Each pixel in the damage proxy map is about 30 meters across.

Image credit: NASA/JPL-Caltech/ASI

Note: For more information, see PIA17700: NASA Spacecraft Shows Before/After of Typhoon Haiyan's Devastation, NASA Damage Map Helps in Typhoon Disaster Response and NASA Peers Into One of Earth's Strongest Storms Ever.

Tuesday, November 12, 2013

Beijing, China


Beijing, Capital of China, photographed by ESA astronaut Paolo Nespoli during the celebrations of the Chinese New Year, "Spring Festival" on 2 February 2011. Do you see any fireworks?

Photo credit: ESA/NASA

Saturday, November 9, 2013

Naples, Italy


Taken at night from the International Space Station this picture is easily recognizable as Naples, Italy because of the black hole in the bright lights: Mount Vesuvius. Understandably, few people live on the still-active volcano meaning no street lights or houses illuminate the area.

The center of Naples is slightly above and to the left - the brightest part of the image. To the left is the Mediterranean Sea with the islands of Ischia, Procida and Capri lit-up to reveal human presence.

The image was taken on a clear night from 400 km above but it was not cloud free around Naples. The top half of the image shows gray clouds.

This image was taken with the Nightpod camera-stand that tracks the movement of Earth passing under the International Space Station at 28,800 km/h, keeping any target fixed in the middle of the viewfinder. Standard cameras fixed to Nightpod can take pictures with longer exposure times so astronauts can take sharper pictures of cities at night.

Photo credit: ESA/NASA

Wednesday, November 6, 2013

Namib Desert


The Namib Desert is a coastal desert in southern Africa. This portion in central Namibia consists entirely of linear and longitudinal sand dunes. Owing to its antiquity, the Namib may be home to more endemic species than any other desert in the world. Most of the desert wildlife is arthropods and other small animals that live on little water, although larger animals inhabit the northern regions. The image was acquired June 18, 2000, covers an area of 55.5 x 57 km, and is located at 25.5 degrees south latitude, 15.1 degrees east longitude.

Photo credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team