ISS017 Earth Sciences and Image Analysis Photographic Highlights

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Lake Pontchartrain and the Bonnet Carre Spillway, Louisiana: Lake Pontchartrain, immediately north of New Orleans, occupies the upper part of this astronaut photograph from April 29, 2008, with the winding course of the muddy Mississippi River snaking across the bottom of the view (flow is eastward, from left to right). The city of New Orleans is sandwiched between the lake and the river.

Heavy rain in March and April 2008 in the Mississippi's catchment area raised water levels in the river enough that the Army Corps of Engineers had to take action to prevent flooding. To reduce the volume of the river through New Orleans, the Corps opened the Bonnet Carre Spillway (lower left), which diverts some of the river's flow into Lake Pontchartrain. Located about 18 kilometers (about 11 miles) upriver from New Orleans, the Bonnet Carre Spillway is a 1.6-kilometer-wide (1-mile) gap in the developments along the Mississippi River levees. The spillway control structure itself is visible as a thin, discontinuous, white line along the river's edge in this image.

The spillway has only been opened eight times since 1937. News of the opening in April 2008 was transmitted to astronauts aboard the International Space Station who managed to capture the immediate effect of muddy water flowing down the spillway and into Lake Pontchartrain. The flood plume forms great brown lobes in the otherwise green water. These lobes moved slowly east along the New Orleans shoreline. The line of the Lake Pontchartrain Causeway, the longest bridge in the United States, is visible cutting across the lake.

As the southernmost spillway in the Corps of Engineers flood control infrastructure for the Lower Mississippi Valley, the Bonnet Carre plays a major role in protecting New Orleans from flooding. Opening the spillway protects the city in various ways. First, it lowers water levels and reduces both the speed of flow and cross currents in the river, which can interfere with vessels navigating the river--or even cause collisions with levees. It also reduces pressure on downstream levees, some of which famously collapsed during the onslaught of Hurricane Katrina in 2005.

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Zion Canyon, Utaha: Zion National Park is located in southwestern Utah, along the western margin of the Colorado Plateau. The park was established in 1919, after roadway improvements in southwestern Utah allowed access to the preceding Mukuntuweap National Monument (1909), located in Zion Canyon. The towering cliffs bounding the North Fork of the Virgin River are formed mainly of tan to light pink Navajo Sandstone, the remains of a sand dune sea that covered the area during the early Mesozoic Era, nearly 200 million years ago. At that point in its history, the Zion region would have looked much like the present-day Sahara Desert.

Younger, brown rock that caps the Navajo Sandstone (image right) records how the environment fluctuated between shallow seas and deserts. This high-resolution astronaut photograph illustrates the incised nature of the bedrock in the park. The long linear features are fractures in the rock—joints—caused by tectonic stresses. The mainly north-northwest trending joints channel water runoff, and they appear to be the main factor that determined the present canyon network.

While the park is perhaps best experienced by hiking, backpacking, or biking, Utah State Route 9 (SR-9) provides automobile access up the side of Zion Canyon. The road is visible in the astronaut photograph as a thin brown line climbing the south wall of the canyon (lower left; more obvious in the large image). Access to the rest of the park is provided by a shuttle bus system instituted in 2000 to reduce vehicle noise, improve air quality, and improve wildlife habitat.

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Volcanic Plumes and Vog, Hawaii: For 25 years, Kilauea volcano on Hawai’i’s Big Island has been erupting continuously. Recent explosive activity that started in March 2008 produced increased emissions of sulfur dioxide. These emissions result in a widespread caustic volcanic fog— known as vog—that, depending on local winds, drifts as much as 200 miles up the volcanic chain, burning throats and eyes and inducing asthma attacks as far away as Honolulu, on the island of Oahu.

An oblique view (the astronaut was looking towards the southwest, rather than straight down) of the Hawaiian Islands taken from the International Space Station on a hazy spring day includes a regional view of three volcanic plumes from Kilauea that contributed to the vog: the plume from Halema’uma’u crater near the summit (a), a plume from Pu’u O’o vent along the east rift (b), and a plume from where lava enters the ocean on the coast outside of the park boundaries (c). At the time this image was taken, doctors throughout the state of Hawaii were reporting an increased caseload of people with respiratory problems.

Aside from the vog, this image captures cloud formations that reveal the large-scale air flow and the local wind patterns around the islands. The parallel lines of clouds aligned roughly northeast to southwest indicate the direction of the region’s prevailing trade winds. That flow is disrupted around the islands (between Hawai’i and Maui, image right), and it is further influenced by the local land-sea breeze, which at that time had driven the cloud formations offshore and caused them to circle the islands. In addition to the Kilauea plumes, the volcanoes of Mauna Loa and Mauna Kea are also visible on the island of Hawai’i (image center). The uninhabited island of Kaho’olawe is just visible to the southwest of Maui.

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NASA Ames Research Center, Moffet Field, CA: This astronaut photograph illustrates the diverse built environment surrounding the NASA Ames Research Center located at the southernmost end of San Francisco Bay. Founded in 1939 as an aircraft research laboratory, Ames became a NASA facility in 1958. Its original aircraft research focus was enhanced by the adjacent Moffett Field—an active Naval Air Station until 1994, and the original home of the Navy dirigible U.S.S. Macon. The large hanger for docking the U.S.S. Macon is still present at Moffett Field, and is visible in this astronaut photograph (image center). Today, NASA Ames includes the former Naval Air Station, and it continues its focus on aeronautics in addition to nanotechnology, information technology, fundamental space biology, biotechnology, thermal protection systems, and human factors research.

Land use and land cover in the southern San Francisco Bay area is a diverse mix of industrial, institutional, and residential patterns. Industrial lots, characterized by lack of green vegetation and large buildings with highly reflective white rooftops, border NASA Ames to the west, east, and south. The city of Mountain View directly to the south appears as a dense gray-brown network of streets and residential properties with interspersed green parks. The northern boundary of NASA ARC consists of former salt ponds that are being restored to tidal wetlands (image right). Drainage channels that predate the salt pond levees are visible at image right.

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Isla de la Palma, Canary Islands: The Canary Islands, a group of volcanic islands, lie just off the west coast of Morocco in the Atlantic Ocean; at the northwest end of the chain is Isla de la Palma (pictured here). The island started forming as a submarine volcano approximately 3-4 million years ago. Subaerial (above the water surface) volcanic activity and island formation began around 2 million years ago. Most geologists believe the Canary Islands formed over the remnants of an old “hotspot” in the mantle, or mantle plume. The residual hotspot melting produced the magma that resulted in the Canary Island volcanoes. While there is little evidence to support the current existence of a mantle plume, volcanic activity is still taking place—the most recent lava flows on Isla de Palma were erupted in 1971. In addition to volcanic hazards, the Canary Islands are also subject to occasional dust storms originating in the Sahara Desert.

This astronaut photograph highlights volcanic landforms on the southern portion of Isla de la Palma. The elongated, 1,949-meter (6,394-foot) high Cumbre Vieja volcanic center is characterized by numerous cinder cones, craters, and gray lava flows that punctuate the green vegetated hills. To the north, the cities of El Paso and Los Llanos de Aridanes nestle against collapsed fragments of the Caldera Taburiente (image left), formed by massive slope failure of an older volcanic center to the north. Tourism is a major component of the local economy, but the high mountains and clear air of Isla de la Palma are also attractive to astronomers; several large observatories (not shown) are located along the northern edge of the Caldera Taburiente.

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Vermillion Cliffs and Paria River, Arizona: The largest tributary of the Colorado River between Lake Powell and the Grand Canyon, the Paria River flows southeast from its headwaters in southernmost Utah to join the Colorado River between Page, Arizona, and Marble Canyon. The Paria River provides spectacular scenery, and is known for the very narrow “slot” canyons that it cuts through the layered rocks of the Colorado Plateau. These canyons formed over millions of years by water erosion slicing deep into the rock layers. Exploring the river channel through the slot canyons is a popular activity for hikers and backpackers. Indeed, there is no road access to much of the river channel, and hiking in on foot is the only way to experience the slot canyons.

The Paria River also exposes the red and white layers of rocks beneath the Paria Plateau that are known as the Vermilion Cliffs (image center). These rocks record the changing environmental conditions of the region during the early Mesozoic Era (248 to 65 million years ago), ranging from widespread deserts to more water-rich periods when rivers flowed across the landscape. The spectacular scenery of the Vermilion Cliffs and Paria Canyon falls within the Vermilion Cliffs National Monument. This rugged and remote landscape is also home to many species of raptors, including the California condor, and other desert fauna like bighorn sheep.

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Santorini Volcano, Greece: One of the largest volcanic eruptions in the past 10,000 years occurred in approximately 1620 BC on the volcanic island of Santorini in the Aegean Sea. This astronaut photograph illustrates the center of Santorini Volcano, located approximately 118 kilometers to the north of Crete (not shown). Prior to 1620 BC, the island of Santorini, now known as Thera, was built up by layers of lava created by overlapping shield volcanoes, and it had experienced three significant eruptions that formed overlapping calderas, or collapsed magma chambers. Around 1620 BC, the fourth (and latest) major eruption created the present-day islands and caldera bay of Santorini Volcano. The caldera rim is clearly visible in this image as a steep cliff forming the western shoreline of the island of Thera.

Following the 1620 BC eruption, much of the previous island of Santorini was destroyed or submerged; this event may have been the inspiration for the legend of the “lost continent” of Atlantis. Far from legend however, many archeologists believe that the eruption was a major factor—or the immediate cause—of the destruction of the classical Minoan civilization of Crete.

The white rooftops of cities and towns trace the caldera rim on the island of Thera, and overlook the young central islands of Nea Kameni and Palaea Kameni, which both formed from lava domes and flows that started erupting approximately 1,400 years after the cataclysmic 1620 BC event. Several of these flows are visible in the image as brown to dark-brown irregular masses forming Nea Kameni (image left). The most recent volcanic activity in the Kameni islands occurred in 1950, and included some small explosions and production of lava. The extent of development, and location of an airport (image upper right) on Thera illustrate the popularity of Santorini Volcano as a tourist destination. Today, volcanic activity is closely monitored by the Institute for the Study and Monitoring of the Santorini Volcano, or ISMOSAV.

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Toshka Lakes, Egypt: In the late 1990s, Egypt’s new manmade Toshka Lakes, fed from Lake Nasser via a canal, grew and spilled into new basins to become four major and two smaller lakes. These lakes extended 120 kilometers across the desert west of the Nile River in southern Egypt. Starting in 2002, astronauts have seen the lakes slowly decline, with the telltale ring of darker, moistened ground showing the previous higher water levels (see prior comparison of astronaut imagery of the lakes). The rise and fall of Toshka Lakes and the economic development surrounding the region are dependent on climate fluctuations and water agreements with upstream countries that, in turn, determine the long-term water flow in the lower Nile.

This astronaut photograph, covering a distance of 11.3 kilometers from left to right, shows shoreline detail of the third large lake. Lake water appears deep blue to blue-green, and parallel with the shoreline is a wide brown zone which was under water until 2002. Most of the bright yellow sand dunes in the view are re-emerging as the lake level drops; most are outlined by thin wet margins. Still-submerged dunes can be seen offshore as blurred tan smudges (image top center). The summit of the biggest horn-shaped dune (image top right) was an island more than five kilometers offshore in images from 2001. The patterns of the overlapping crescent dunes gives a strong sense of dune migration southwards; the horns of the crescent dunes point in the direction of dune movement, from top right towards lower left. Dominant northerly winds drive the dunes southward, except, of course, when they are under water.

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Fires in California: One of the largest and most destructive fires raging across California over the weekend of July 4 was the Basin Fire, threatening Big Sur, and covering the coast in a thick blanket of smoke. Astronaut Greg Chamitoff, observing the fires from 344 kilometers (215 miles) above the Earth aboard the International Space Station, was able to capture the regional view of the smoke pall. At the time this image was taken, more than 300 fires were burning in California alone. The Basin Fire was triggered by a thunderstorm, had burned more than 80,000 acres, and as of July 10, was still only partially contained.

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Piute Fire, Sequoia National Forest: The Piute Fire, burning south of Lake Isabella in the Sequoia National Forest in the southern Sierra Nevada Mountains, was one of the more than 300 wildfires burning across the state of California in early July 2008. The fire started June 28 just north of Twin Oaks, California, and had burned nearly 34,000 acres as of July 10, according to reports from the National Interagency Fire Center. They estimated the fire might not be brought under control for another 2 weeks.

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