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Space Photography

pictures photographs earth astronauts

PAUL E. LOWMAN, PH.D.
Goddard Space Flight Center, NASA

This term is a broad one that could, in principle, be applied to any photograph taken in “space,” or above approximately 100km (50 miles) altitude and include images acquired on film or electronically. Weather satellites alone generate hundreds of images of the earth from space daily. However, this section will summarize photographs of the earth’s surface and those on and near the moon taken by astronauts, and their influence on remote sensing.

The first pictures of the earth from space were acquired shortly after World War II, when rockets launched from White Sands Proving Ground in New Mexico reached altitudes of 160km (100 miles) or higher. Many of those images were of high photographic quality, and resulted in panoramic views of the southwestern United States that are impressive even today. These photographs helped stimulate interest in the meteorological applications of images from space, leading to the first weather satellite, TIROS 1, in 1960. However, they also interested geologists in the use of space photography to study poorly mapped areas and geologic structures of regional extent such as the San Andreas fault zone. P.M. Merifield suggested that the first American astronauts, of Project Mercury, be asked to take geologically useful photographs during their short missions. On the very last such mission, lasting 34 hours, L. Gordon Cooper obtained many excellent color pictures of southern Asia, Tibet in particular, which was then a poorly mapped area. Cooper’s pictures, taken with a 70-mm hand-held camera and on Anscochrome film, led to the inclusion of synoptic terrain photography on almost all of the Gemini missions.

The Gemini flights of 1965 to 1966 were part of the Apollo program, and were used to develop the technology and space operational methods such as rendezvous for the eventual Apollo missions to the moon. They lasted as long as 14 days, and the astronauts returned approximately 1100 color pictures, mostly on Ektachrome, useful for geology, geography, and oceanography. Published widely when space flight itself was still something of a novelty in magazines such the National Geographic , these spectacular pictures generated enormous public and scientific interest. Weather satellite pictures were familiar by the mid-1960s, but the high-resolution, 70-mm color photos were a revelation.

The most general effect of the Gemini terrain photographs was to accelerate progress in remote sensing as a whole. However, a specific result was to trigger a series of events that led to Landsat. One of the “events” was that the U.S. Geological Survey along with other agencies, proposed an electronic earth resources satellite called the Earth Resources Observation Satellite (EROS). An interagency disagreement ensued as NASA felt that satellites were its business alone. However, it was decided that the Goddard Space Flight Center would develop the Earth Resources Technology Satellite (ERTS) for the use of the Interior Department or any other potential customers.

ERTS-1 was launched in July, 1972 carrying two sensors, the RCA Return Beam Vidicon camera, and the Hughes Multispectral Scanner. Both worked well and began returning high-quality color images of the earth’s surface. Although initially termed “a solution in search of a problem” by some, Landsat (as ERTS was shortly re-named) soon demonstrated its value. The first such demonstration was the difficulty Goddard scientists had in identifying the area covered by the very first image. It turned out to be Fort Worth and Dallas, hardly a remote area but one in which new reservoir, airport, and highway construction had changed the landscape drastically from that shown on the latest topographic maps. So map revision turned out to be the first “solution” to a “problem.”

Landsat-1 was followed by several successors, each more capable than the last. The electronic “photographs” returned, now numbering in the millions, and taken in a wide variety of spectral bands, have become indispensable tools for innumerable applications from planning petroleum exploration to mapping Antarctic penguin rookeries. Furthermore, the early success of Landsat stimulated other nations, first France, to develop their own earth resources satellites. The first of these, Systeme Probatoire pour l’Observation de la Terre (SPOT), was launched in 1982 and produced excellent pictures. Other countries, such as the Soviet Union and India, produced comparable satellites. Space photography has long since been privatized, and high-resolution color photos are now commonplace. Thousands of once-classified military satellite photos, taken by American satellites under the Corona Program, were released in the mid-1990s.

Hand-held space photography like that taken by Gemini astronauts was resumed in the 1980s, when the shuttle started flying. It used a wider range of hand-held film cameras, including both 35-mm and large format systems. This Space Shuttle Earth Observations Program, administered by Johnson Space Center, has produced many stunning pictures of the earth. The best of these were taken by astronaut Jay Apt and published by the National Geographic Society in Orbit , where he was also its senior author. A big step forward was taken in preparation of this book, in that the original films were digitized, exploiting their high resolution and color fidelity. A few of the older space photos were also digitized, with comparable results.

The crews of the International Space Station have also been taking pictures, this time as part of EarthKam, a program in which students submit requests for photographs of specific areas. These are taken with a digital camera, permitting them to be transmitted to earth almost as soon as they are taken.

The golden age of space exploration was crowned by the Apollo Program, with 6 manned landings on the moon, as well as 2 non-landing missions (Apollo 8 and 10). The entire moon was photographed by the robotic Lunar Orbiter spacecraft, a reconnaissance program to help pick landing sites for the Apollo landings. These photographs are still among the best pictures ever taken of the moon The Apollo astronauts on all lunar missions took thousands of hand-held photographs from lunar orbit, which although not providing systematic coverage are valuable for their rendition of unusual or complex features.

The astronauts who actually walked on the moon took thousands of pictures with hand-held (actually chest-mounted), 70mm photographs with modified versions of the Hasselblads used on all missions since the third Mercury mission (MA-8). The best of these pictures were published in a David Light’s collection Full Moon . Produced by digitizing the original pictures, color and black and white, the surface photographs are a striking tribute to the skill of the astronauts and the ability of the photographic technicians who chose the equipment and specified the techniques.

The lunar surface photographs were perhaps the most difficult ever taken by hand-held film cameras. The illumination, full-spectrum sunlight, is literally “unearthly.” The photometric function of the surface is anomalous by terrestrial standards, with strong backscattering in down-sun views. At first glance the lunar surface is a montage of black and white
with little inherent color at close range. This is because of the near-total absence of ferric iron oxides that account for the browns and reds of terrestrial rock and soils. However, there is more color than one would think—subtle browns and grays that depend strongly on the viewing direction. The astronauts eyewitness descriptions are valuable in reproducing their photographs accurately, but their eyes had to peer through plastic face-plates, generally with lowered visors. Despite these technical challenges, the Apollo surface photographs were generally perfectly taken and visually stunning, to say nothing of scientifically valuable.

Several years passed between the last American manned mission and the first launches of the space shuttle in 1981. Astronaut photography from the shuttle became an extensive activity, evolving into the permanent and formal Space Shuttle Earth Observations Project. A few flights used a remarkable large format camera (LFC), which was mounted in the shuttle payload bay. This 405-kg camera had a 305 mm, f/6 lens and a 23 × 46 cm format. At a typical altitude of 300km (186 miles), a frame covers ground dimensions of about 225 × 450km (140 × 280 miles). Some shuttle flights also included an IMAX large-format movie camera.

Given the variety of equipment and requirements, shuttle crews are obliged to match optimal equipment with the subject and receive extensive training in photography and in subjects such as geology, meteorology, oceanography, and ecology. However, the Hasselblad 70 mm is still the workhorse, usually with Ektachrome 64 film. Astronauts have also used an electronic (digital) still camera successfully on recent flights.

The value of space photography was almost totally unpredicted before space flight actually began, except for meteorology and military purposes. However, images of and by astronauts have changed our view of our planet, its satellite, and their place among the stars. In the last few decades, it has become a shining example of serendipity, one that alone would go far toward justifying the expense of space flight.

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