| ||EB/ES 351 Manned|
James S. Aber
Historical Introduction Manned space photographs of the Earth began with the Mercury, Gemini, and Apollo missions of the 1960s. Many spectacular images of the lands, oceans, and atmosphere were obtained, and these demonstrated the potential of synoptic space photography for various earth science investigations. With few exceptions, these photos were taken at the discretion of astronauts, who had little formal background in either photography or earth science.
Systematic manned space photography was undertaken during the Skylab missions of 1973 and 1974. Skylab was a orbiting space station that was utilized for extended Earth observations. The overall objectives were to determine the quality and quantity of photographic and observational data that could be collected by astronauts with benefit from preflight training and ground support during flight. It was recognized that astronauts needed much additional preflight scientific and operational training to take multidisciplinary photographs (Wilmarth et al. 1977). Skylab 4 was most successful; about 2000 photographs were obtained of more than 850 features and phenomena. The lessons learned during Skylab missions formed the basis for the program of space-shuttle photography in the 1980s and '90s.
| ||South Island of New Zealand.
|| ||Chicago and Lake Michigan, Illinois. |
Space-Shuttle Missions Astronauts on space-shuttle missions have taken more than 300,000 photographs with hand-held cameras. A large portion of these are Earth-looking images that provide unique views of the world's surface features: deserts, volcanoes, mountains, coasts, oceans, glaciers, sea ice, rivers, lakes, dust, fires, clouds, and human settlement. Space-shuttle photographs are taken in all possible orientations--near vertical, low oblique, and high oblique--for a greater range of perspectives than is possible with any unmanned satellite instruments.
Space-shuttle photography is the result of systematic Earth and environmental science training given to each astronaut crew prior to flight. Much of the photography consists of revisits to targets previously photographed. Each day during flight, astronauts are given instructions for photographs based on cloud cover and orbital conditions. Astronauts are also free to take photographs of any interesting or attractive scenes. Special advantages of astronaut photography include the following (Lulla et al. 1993).
Various cameras, lenses, and film types are employed for space-shuttle photography. Hasselblad cameras are most commonly used. These take pictures with 70-mm (2¾-inch) format film. Lenses vary from 40 mm to 250 mm focal length. The Linhof camera is also utilized on most missions; it takes 125-mm (5-inch) format film. Other still cameras that have been used include: Rolleiflex (70 mm), Nikon (35 mm), and IMAX and 16-mm movie footage are taken on some flights along with video imagery.
- Images are taken at various sun angles, ranging from negative angles (below horizon) to nearly vertical. This provides for unique views under various lighting conditions that are not available with other remote sensing systems.
- Sequential (overlapping) near-vertical photographs with different look angles provide for stereoscopic viewing.
- Little-known tropical areas are well represented in the photography database. These regions are undergoing very rapid human-induced environmental transformations.
The Large Format Camera (LFC) was carried onboard Challenger mission 41-G in 1984. This enormous camera took 23 x 46 cm (9 x 18 inch) images on various panchromatic, color, and color-infrared films. A 305 mm (12 inch) lens was used, which resulted in ground coverage of 225 x 450 km per photograph and resolution of 14 to 25 m. More than 2500 photographs were acquired, but they originally were classified because of their excellent resolution. The EROS Data Center now distributes LFC products without restrictions.
| ||Hasselblad camera onboard shuttle.
|| ||Linhof camera at ground briefing.|
| ||Nikon camera onboard shuttle.
|| ||Hasselblad camera onboard shuttle (taken with the ESC). |
| ||Front view of the LFC on display at the EROS Data Center, Sioux Falls, South Dakota. Photo date 7/98; © J.S. Aber.|
| ||Back view of the LFC on display at the EROS Data Center, Sioux Falls, South Dakota. Photo date 7/98; © J.S. Aber.|
The electronic still camera (ESC) is a charged-couple device that produces near-film-quality images in digital format. It has been utilized on several missions since 1991. The ESC system has three components: (1) hand-held fully digital and programmable, high-resolution camera, (2) lap-top computer for onboard image processing and downlink, and (3) ground station for reception, processing, and distribution of digital data and images (Lulla and Holland 1993). Current spectral response range is 0.4 to 1.1 µm, which is greater than films now in use.
Film selection for space-shuttle photography is relatively conservative. Most photographs are exposed on color-visible films of various types. Color-infrared film is used occasionally, and other special film types are employed rarely. Most photographs have been digitized and converted to video format. "Digitization, rectification, multi-layering (GIS), classification, and mensuration of these digitized analog images is now fairly routine ..." (Lulla et al. 1993).
| ||Color-infrared view of Bangkok, Thailand.
|| ||Color-infrared view of Mount St. Helens, Washington.|
The ground coverage of space-shuttle photography is determined by factors of orbit geometry that vary with each mission. The most important factor is orbit inclination, ±28.5° for most early missions, which limited photographs to low-latitude locations. This includes about one-half of the Earth's surface, an area with more than 75% of the world's human population. Orbital inclinations from ±34.3° to a maximum of ±57° are used on some special missions and to reach the international space station. For the latter, regions up to around ±60° latitude can be photographed in oblique views. High-latitude areas above the Arctic and Antarctic Circles are photographed rarely.
Time of launch and crew sleeping schedules affect the times of daylight when photographs may be acquired, as very few pictures are taken on the Earth's night side. Thus, some missions return pictures mainly from the northern hemisphere, whereas other missions take photos mostly in the southern hemisphere. An important factor is cloud cover that often obscures ground features of interest. For example, certain equatorial sites have little or no cloud-free photographs. Photography is not the primary objective on most space-shuttle flights, so pictures are taken when astronauts are not busy with other duties. The result of these factors is quite uneven coverage of the world.
| ||Snow-covered view of Finger Lakes, New York.
|| ||Sea ice, Bristol Bay, Alaska.|
| ||Florida peninsula, Gulf of Mexico, and Atlantic Ocean.
|| ||Irrigation in Saudi Arabia.|
| ||Ganges River delta, Bangladesh and India.
|| ||Tibet Plateau and Himalaya Mountains, China, Nepal, and India.|
| ||Deforestation in Brazil.
|| ||Eleuthera Island and shelf, Bahama Islands. |
Manned-space photography has been utilized for several global-change studies. These include monitoring of inland water bodies in climatically sensitive areas: Great Salt Lake, Aral Sea, Lake Chad, etc. Photographs have also been used to document changes in deltaic and estuarine environments, for example the Omo delta of Lake Turkana. Space-shuttle photographs have proven valuable for studies of ephemeral events, such as volcanic eruptions, dust storms, and man-made fires.
| ||Lake Chad, Africa.
|| ||Oil slick in Persian Gulf.|
| ||Aral Sea, Kazakhstan.
|| ||Eruption of Kliuchevskoi volcano, Kamchatka, Russia.|
| ||Great Salt Lake, Utah.
|| ||Smoke from forest fire, Queensland, Australia. |
The presence of human photographers in space provides some important capabilities: to observe and respond quickly to unusual ground events, to preselect and acquire scientifically useful images, and to photograph phenomena from different look angles. "These qualities demonstrate the value of a human observer in orbit in adding to understanding of our planet Earth, and interacting with ground scientists in real time to acquire data and confirm or deny events." (Lulla and Helfert 1991)
The space shuttle system was retired in 2011 after three decades of service and more than 130 missions—see shuttle retirement. Since then, the International Space Station has taken over as the primary platform for manned space photography of the Earth. Of particular interest is the cupola window built by the European Space Agency and installed in 2010.
NASA Johnson Space Center—Imagery services.
NASA Johnson Space Center—Earth from space.
Lulla, K. and Helfert, M. 1991. Smoke palls induced by Kuwaiti oilfield fires mapped from space shuttle imagery. Geocarto International 6/2:71-80.
Lulla, K., Helfert, M., Evans, C., Wilkinson, M.J., Pitts, D. and Amsbury, D. 1993. Global geologic applications of space shuttle Earth observations photography database. Photogrammetric Engineering and Remote Sensing 59:1225-1231.
Lulla, K. and Holland, S.D. 1993. NASA electronic still camera (ESC) system used to image the Kamchatka volcanoes from the space shuttle. International Journal Remote Sensing 14:2745-2746.
Wilmarth, V.R. et al. 1977. Skylab explores the Earth. NASA Special Publication 380, 517 p.
Return to course schedule.
EB/ES 351 © J.S. Aber (2016).