yee@trident.arc.nasa.gov (Peter E. Yee) (03/16/89)
Charles Redmond NASA Headquarters, Washington, D.C. March 14, 1989 James Hartsfield Johnson Space Center, Houston RELEASE: 89- DISCOVERY'S RETURN-TO-FLIGHT PHOTOGRAPHS RECORD MANY FIRSTS Earth observation photographs taken by Discovery's crew during America's return to piloted space flight in 1988 were among the clearest in more than 20 years, and they captured a variety of environmental conditions. Included in the astronauts' photography from the September 1988 mission is a photograph showing at least a 1 million square- mile smoke cloud over South America's Amazon River basin and, in Africa, evidence of flooding in areas that have experienced a lengthy drought. Due to an unexpected improvement in atmospheric clarity over the Northern Hemisphere, the Discovery crew could distinguish ground details about 700 miles away from their spacecraft, much farther than has been normal for Space Shuttle flights. Visibility over the Northern Hemisphere during STS-26 was the best since the 1960s Gemini Program flights. In total, the crew took 1,505 photographs of Earth during the 4-day mission. Discovery was launched into an orbit that kept it above only the tropical and subtropical regions of Earth. That orbit took the spacecraft over about half of Earth's surface, covering parts of 122 nations and regions that hold about 75 percent of the world's population. Photographs show a dense, white smoke cloud, the result of tropical forest, pasture and croplands being cleared and burned, completely obscuring the ground over much of South America's Amazon River basin. If placed over the United States, the same cloud would cover an area of the country more than three times the size of Texas. It is the largest and thickest accumulation of smoke ever photographed by astronauts, much larger than the previous largest smoke cloud photographed by astronauts over the same region in 1984. STS-26 also photographed smoke clouds over Sumatra and Borneo, Indonesia, Madagascar, eastern Africa, northern Australia and Bolivia. Some photographs show apparent irrigation features in the tropics -- in areas that normally receive 100 inches of annual rainfall. In Africa, the "green line" of vegetation that generally marks the southern boundary of the Sahara Desert had moved the farthest north it has been in astronaut photography since 1965. Also, standing water was photographed in the Sahara. For the first time in Shuttle history, Africa's Niger river was photographed in full flood and out of its banks. Photographs of the Blue and White Nile rivers also showed evidence of recent flooding. Throughout eastern Africa, the landscape was tinted with green, a condition never before seen in this region during the Shuttle program. Still, Africa's Lake Chad and Lake Nasser, two lakes that have long been studied by space photography, were at the lowest levels ever photographed by astronauts. Since 1960, Lake Chad's surface area is estimated to have declined by more than 90 percent. The extreme atmospheric clarity over the Northern Hemisphere during the mission was due, at least in part, to the absence of major global duststorms. Duststorms of million-square mile dimensions over northern Africa, even extending halfway across the Atlantic Ocean, were photographed during 1984 and 1985 Shuttle flights. But no such African duststorms were seen during STS-26, nor were major duststorms observed elsewhere. A lack of recent major volcanic eruptions, which cause dust in the upper atmosphere, also may have contributed to the extreme clarity. As a result, the STS-26 photographs captured details not usually seen in Shuttle photography: for the first time, an aircraft was photographed generating a contrail; individual buildings could be seen in the Canary Islands; a line of electrical transmission pylons was seen in southern Sudan; and oil platform flares were seen in the Gulf of Campeche. STS-26 also photographed the effects of Hurricane Gilbert on the Mexican Gulf Coast and five volcanoes with signs of eruptive activity. Earth photography from the Space Shuttle is managed by the Space Shuttle Earth Observations Office at the Johnson Space Center. The office trains Shuttle crews in Earth photography, selects targets for photography for each mission and analyzes the resulting photographs. In addition, research is conducted by specialists in environmental sciences, biology, climatology, geology and other fields using data obtained with Shuttle photography.