Space oceanography encompasses oceanographic research and technological development resulting from manned and unmanned systems in earth orbit. These systems observe and measure oceanographic parameters such as sea-surface winds, sea-surface temperatures, waves, ocean currents, and frontal regions. The scope of oceanographic research embraces the sciences of physics (including acoustics), geology, biology, and chemistry. The technological development includes new sensing methods and sensor systems to acquire oceanographic data with specified degrees of resolution, accuracy, coverage, and timeliness.

      Some oceanographic phenomena were first observed and photographed by astronauts in space. Sensor technology often then evolved to observe the same phenomena from unmanned spacecraft. As our scientific knowledge of the world's oceans increases, and as a consequence the accuracy of the physics in oceanographic forecasting models improves, there arises a need for a real-time, global (encompassing all ocean basins), daily oceanographic observation system. Such an observation system can only be achieved in a cost-effective manner from an unmanned space system. However, the human eye and brain, with the aid of optics, have the ability to observe oceanographic phenomena in the visual part of the electromagnetic spectrum over broader physical scales and between more subtle changes in color than any unmanned sensor technology currently being flown in space. As a consequence, humans in space are a unique tool in the conduct of oceanographic research.

      The photographs in this book are examples of oceanographic phenomena observed by U.S. astronauts from space. The ability to observe sets of internal waves as they propagate through the Strait of Gibraltar, the complex linking of spiral eddies, and the continuous scar of ship wakes covering hundreds of miles on the ocean surface are prime examples of oceanographic phenomena the existence or extent of which were not previously known or fully appreciated. Discoveries such as these from space have led to new research efforts and in some cases dispelled previously held scientific notions.

      Where possible, the approximate direction of north has been indicated on the photographs contained in this volume. However, in some instances, such an orientation was not possible due to the absence of any identifiable geography or information on the direction the astronauts were pointing the camera relative to the direction of flight of the space shuttle.

      The purposes of this book are to educate and stimulate those who conduct oceanographic research and to illustrate the ocean's complexity to those who operate on or below the ocean's surface through the publication of an excellent collection of oceanographic photographs taken by the men and women of the United States who have flown into space.

      This collection of photographs was selected by Dr. Robert E. Stevenson and represents one result of many years of his personal effort to educate the NASA astronaut corps to observe the world's oceans during their flights into outer space. This book is dedicated to Dr. Stevenson and to the NASA astronauts who observed the oceans from space.

Captain David C. Honhart, USN Office of the Chief of Naval Research June 1989