Space-based Observations of the Earth

By David Herring and Michael King
May 11, 2000

Reprinted here with permission of the Encyclopedia of Astronomy and Astrophysics, published by IOP Publishing/Macmillan in 2001.

In the wake of World War II, the U.S. Naval Research Laboratory began experimenting with German-designed V-2 rockets as well as smaller, lighter launch vehicles called "sounding rockets." In order to monitor which way the rockets were pointing during their flights, scientists began putting aircraft gun cameras on them. During one of these flights, on March 7, 1947, the first space-based picture of Earth was taken at an altitude of 100 miles over New Mexico. In 1950, upon developing the film after another of these flights, scientist Otto Berg discovered a series of pictures of a huge tropical storm over Brownsville, Texas. He pieced the pictures together into a mosaic of the region enveloped by the storm, thus demonstrating the potential for space-based cameras to help us monitor our changing world.

Photo from Sounding Rocket

Interest quickly grew among the international community of Earth scientists in using sounding rockets to study the Earth's upper atmosphere. In 1952, the International Council of Scientific Unions proposed declaring 1957 the "International Geophysical Year" (IGY) to satisfy a growing desire among the science community to expand the study of our home planet to include the whole Earth system and its surroundings. In 1954, the IGY committee challenged participating countries to launch a satellite as part of the IGY activities. On July 29, 1955, President Dwight Eisenhower announced that the United States would launch about six Earth satellites as a contribution to the IGY. On the following day, Premier Nikita Kruschev said the Soviet Union would also launch satellites during the IGY and the race was on between the superpowers.

In October 1957, the Soviet Union successfully launched Sputnik I—a 22-inch spherical satellite weighing 175 pounds—into a low Earth orbit. In January 1958, the United States successfully launched Explorer I, followed by the launch of Vanguard I two months after that. But the Russians' success and the United States' initial failures spread a sense of crisis in the latter country. The Americans declared space exploration a national priority, and in 1958 President Eisenhower asked his Science Advisory Committee to write a policy on space. Later that year Congress signed the act creating the National Aeronautics and Space Administration (NASA). Since then, NASA has played an international leadership role in developing and deploying satellite technologies for Earth observation.

next: A Space-based Perspective

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Space-based Observations of the Earth

Introduction
A Space-based Perspective
Earth is a Dynamic Planet
From Observing to Measuring Changes on Earth
Towards Predicting Climate Change
Conclusion

Left: This photo was taken by an automatic K-12 camera, using black and white infrared film, from a Viking sounding rocket that reached a height of 227 km (141 miles). The film was recovered from the crashed vehicle after it fell back to Earth. The scene viewed here extends southwestward across parts of New Mexico, Arizona, Nevada, California, and northwest Mexico (upper Gulf of California on the left).

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