Monthly Archives: March 2017

Mar302017

NASA: Africa from Space as you’ve never seen it before

NATURE & TOURISM

Quartz

The Nile river in Africa sparkles in this night observation taken by NASA astronaut Scott Kelly on July 27, 2015.
The magnificent Nile at night in 2015. (NASA/Johnson Space Center)

It can often be challenging to find alternative viewpoints of Africa. Perceptions of the continent are so colored by decades of stereotyped coverage and biased academic study that it can be hard to sift through the misinformation to understand the reality.

Often that search requires taking a step back. And now there’s a unique and literal opportunity to do so, via a new image and video library database launched by NASA this week. The site pulls together more than 140,000 images, videos, and audio files from 60 NASA collections—some of them decades old—for the public to explore, download, and use for the first time.

These images, culled from uploads and popular image searches of “missions in aeronautics, astrophysics, Earth science, and human spaceflight,” offer an often unseen view of Africa’s geographic beauty—without commentary.

It drains a watershed that spans eight countries and nearly 1.6 million square kilometers (600,000 square miles). The Zambezi (also Zambeze) is the fourth largest river in Africa, and the largest east-flowing waterway.
A natural color satellite image of Africa’s fourth largest river, the Zambezi, taken in 2013. (NASA/JPL)
This east-looking view shows most of the east-west extent of the country of Sudan. The foreground shows a vegetation-less and almost uninhabited region of northwest Sudan. The rich earth colors are ancient soils (browner and redder tones), a concentrated mass of what may be volcanic cinder cones (dark brown dots - center) and dune and younger river sediments (yellows). The photo would have been difficult to locate had it not been for two recognizable features in the background: a visually well-known inselberg ("island mountain" -- top center) on a large west-bank tributary of the White Nile; and the confluence of the Blue and White Nile's, with the great cotton developments of the Gezira Scheme between them (top left). The Red Sea coast is almost obscured by a dust cloud but can be discerned running across the top of the picture. The clouds at top may be developing over the coastal ranges of Saudi Arabia beyond the Red Sea.
An almost uninhabited region of northwest Sudan is pictured in 1994. (NASA/Johnson Space Center/)
Astronauts aboard the International Space Station captured this image of a huge crater in Africa on Nov. 22, 2014. This is the Richat Structure in northwestern Mauritania, otherwise known as the “Eye of the Sahara.” Scientists are still deciding whether this was formed by a subterranean volcano or impact from a large meteor. Deep in the Sahara Desert it is nearly a perfect circle, it is 1.2 miles (1.9 kilometers) wide, and sports a rim 330 feet (100 meters) tall. The crater sits in a vast plain of rocks so ancient they were deposited hundreds of millions of years before the first dinosaurs walked the Earth.
The ancient Richat Structure in northwestern Mauritania, also known as the “Eye of the Sahara” was captured by astronauts aboard the International Space Station in 2014. It is a nearly perfect circle, and scientists are unclear whether it was formed by an underground volcano or a meteor impact. (NASA/Johnson Space Center)
This image shows several of the Canary Islands, located in the North Atlantic Ocean just west of Africa. Low level stratus clouds often form here (and along the west coast of continents at these latitudes) are trapped in vertical movement due to an overlying atmospheric temperature inversion. The islands are generating disturbances in the low-level wind flow which is generally from the north-northeast or from top to bottom in the image. These disturbances travel downstream from the islands and manifest themselves as cloud swirls which are called von Karman vortices. The northern extent of a large dust storm moving off the coast of Africa is apparent at the lower right of the image. The dust, extended across the Atlantic Ocean as far west as the Dominican Republic later in the mission.
The Canary Islands, just west of Africa, are pictured under a swirl of clouds in 1991. (NASA/Johnson Space Center)
A 1992 photograph from the Space Shuttle Endeavour shows deforestation in the Democratic Republic of the Congo (then Zaire) in 1992. The light green areas are farmland, which contrast with the dark green of the surrounding canopy forest.
A 1992 photograph from the Space Shuttle Endeavour shows deforestation in the Democratic Republic of the Congo (then Zaire) in 1992. The light green areas are farmland, which contrast with the dark green of the surrounding canopy forest. (NASA/Johnson Space Center)
Okavango Swamp in Botswana is featured in this image photographed by an Expedition 28 crew member on the International Space Station. This short focal-length photograph shows the entire Okavango ?delta,? a swampland known in Southern Africa as the ?Jewel of the Kalahari Desert?. This enormous pristine wetland of forest, wildlife, and freshwater almost miraculously appears in a desert where surface water is typically non-existent. The water comes from the Okavango River which rises in the high-rainfall zone of southern Angola, hundreds of kilometers to the northwest. The dark green forested floodplain is approximately 10 kilometers wide where it enters the view (left). The Okavango then enters a rift basin which allows the river to spread out, forming the wetland. The width of the rift determines the dimensions of the delta?150 kilometers from apex to the linear downstream margin (right). The apex fault is more difficult to discern, but two fault lines actually define the downstream margin; the fault traces are indicated by linear stream channels and vegetation patterns oriented at nearly right angles to the southeast-trending distributary channels at center. The distributary channels carry sediment from the Okavango River that is deposited within the rift basin. Over time, a fan-shaped morphology of the deposits has developed, leading to characterization of the wetland as the Okavango ?delta?. The drying trend from higher rainfall in the north (left) to less rainfall in central Botswana (right) is shown by the change from the greens of denser savanna vegetation to browns of an open ?thornscrub? savanna. More subtle distinctions appear: the distributary arms of the delta include tall, permanent riverine and seasonal forest (dark green), with grasses and other savanna vegetation (light green) on floodplains?which appear well watered in this image. Linear dunes, emplaced by constant winds from the east during drier climates, appear as straight lines at left. The dunes are 10 meters high and their sands hold enough moisture for some trees to grow on them. Counter-intuitively, the low ?streets? between the dunes are treeless because they are dominated by dense dry white soils known as calcretes.
Channels of the Okavango Delta stretch out into the desert in this view from the International Space Station in 2011. (NASA)
Eastern Mediterranean from an unusually high vantage point over the Nile River, this north-looking view shows not only the eastern Mediterranean but also the entire landmass of Asia Minor, with the Black Sea dimly visible at the horizon. Many of the Greek islands can be seen in the Aegean Sea (top left), off the coast of Asia Minor. Cyprus is visible under atmospheric dust in the northeast corner of the Mediterranean. The dust cloud covers the east end of the Mediterranean, its western edge demarcated by a line that cuts the center of the Nile Delta. This dust cloud originated far to the west, in Algeria, and moved northeast over Sicily, southern Italy, and Greece. Part of the cloud then moved on over the Black Sea, but another part swerved southward back towards Egypt. A gyre of clouds in the southeast corner of the Mediterranean indicates a complementary counterclockwise (cyclonic) circulation of air. The Euphrates River appears as a thin green line (upper right) in the yellow Syrian Desert just south of the blue-green mountains of Turkey. The Dead Sea (lower right) lies in a rift valley which extends north into Turkey and south thousands of miles down the Gulf of Aqaba, the Red Sea, and on through East Africa. The straight international boundary between Israel and Egypt (where the coastline angles) is particularly clear in this view, marked by the thicker vegetation on the Israeli side of the border. The green delta of the Nile River appears in the foreground, with the great conurbation of Cairo seen as a gray area at the apex of the triangle. Most of Egypt's 52 million inhabitants live in the delta. On the east side of the delta, the Suez Canal is visible. On the western corner of the delta lies the ancient city of Alexandria, beside the orange and white salt pans. The World War II battlesite El Alamein lies on the coast.
A 1993 image captures a view of the Nile River, the Eastern Mediterranean, the Euphrates River, and the Dead Sea. (NASA/Johnson Space Center)
Earth Observation taken during a night pass by the Expedition 40 crew aboard the International Space Station (ISS). Folder lists this as: South Africa at night.
South Africa is captured at night in 2014 from the International Space Station. (NASA/Johnson Space Center)

The collection’s space radar images also illuminate with color the richness of Africa’s terrain.

This space radar image shows the Roter Kamm impact crater in southwest Namibia. The crater rim is seen in the lower center of the image as a radar-bright, circular feature. Geologists believe the crater was formed by a meteorite that collided with Earth approximately 5 million years ago. The data were acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) instrument onboard space shuttle Endeavour on April 14, 1994. The area is located at 27.8 degrees south latitude and 16.2 degrees east longitude in southern Africa. The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and vertically received); and blue represents the C-band (horizontally transmitted and vertically received). The area shown is approximately 25.5 kilometers (15.8 miles) by 36.4 kilometers (22.5 miles), with north toward the lower right. The bright white irregular feature in the lower left corner is a small hill of exposed rock outcrop. Roter Kamm is a moderate sized impact crater, 2.5 kilometers (1.5 miles) in diameter rim to rim, and is 130 meters (400 feet) deep. However, its original floor is covered by sand deposits at least 100 meters (300 feet) thick. In a conventional aerial photograph, the brightly colored surfaces immediately surrounding the crater cannot be seen because they are covered by sand. The faint blue surfaces adjacent to the rim may indicate the presence of a layer of rocks ejected from the crater during the impact. The darkest areas are thick windblown sand deposits which form dunes and sand sheets. The sand surface is smooth relative to the surrounding granite and limestone rock outcrops and appears dark in radar image. The green tones are related primarily to larger vegetation growing on sand soil, and the reddish tones are associated with thinly mantled limestone outcrops. Studies of impact craters on the surface of the Earth help geologists understand the role of the impact process in the Earth's evolution, including effects on the atmosphere and on biological evolution.
The undulations of the the Roter Kamm impact crater in southwest Namibia are pictured in 1994. The crater is believed to be about five million years old. (NASA/JPL)
This spaceborne radar image shows how the Atlas Mountains in northwestern Africa dominate the geography of Morocco.
The Atlas mountains in Morocco shown in a space radar image in 1999. (NASA/JPL)

While efforts are underway to improve maps of Africa, we have NASA to thank for images that give us an accurate perspective of the continent’s place in the world.

Africa is front and center in this image of Earth taken by a NASA camera on the Deep Space Climate Observatory (DSCOVR) satellite. The image, taken July 6 from a vantage point one million miles from Earth, was one of the first taken by NASA’s Earth Polychromatic Imaging Camera (EPIC). Central Europe is toward the top of the image with the Sahara Desert to the south, showing the Nile River flowing to the Mediterranean Sea through Egypt. The photographic-quality color image was generated by combining three separate images of the entire Earth taken a few minutes apart. The camera takes a series of 10 images using different narrowband filters -- from ultraviolet to near infrared -- to produce a variety of science products. The red, green and blue channel images are used in these Earth images. The DSCOVR mission is a partnership between NASA, the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Air Force, with the primary objective to maintain the nation’s real-time solar wind monitoring capabilities, which are critical to the accuracy and lead time of space weather alerts and forecasts from NOAA. DSCOVR was launched in February to its planned orbit at the first Lagrange point or L1, about one million miles from Earth toward the sun. It’s from that unique vantage point that the EPIC instrument is acquiring images of the entire sunlit face of Earth. Data from EPIC will be used to measure ozone and aerosol levels in Earth’s atmosphere, cloud height, vegetation properties and a variety of other features. Image Credit: NASA
Africa shown in 2015, one million miles from Earth, in a picture taken by the Deep Space Climate Observatory satellite. The picture is a combination of three separate images of the entire Earth taken a few minutes apart. (NASA/Goddard Space Flight Center)

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