Taking The Earth's Vital Signs

The dramatic photographs that appear in these pages were taken by astronauts aboard U.S. space shuttles. The pictures provide clear evidence that the earth is in grave danger as a result of human activity. Overpopulation, pollution and energy consumption have created such planet-wide problems as massive deforestation, ozone depletion and the global warming that is believed to be caused by the greenhouse effect. Yet these alarming trends, and how they interact with such natural phenomena as hurricanes and volcanoes, are still not fully understood by scientists.

Major help in studying the earth's environment is expected to emerge from a project being planned by the National Aeronautics and Space Administration. Called Mission to Planet Earth, the program would consist of a series of satellite flights designed to monitor the earth with sensitive instruments that measure such vital signs as temperature, winds and atmospheric chemistry. These readings would add immensely to the knowledge gained from high- resolution photography alone. The object is to understand the planet's dynamics well enough to anticipate ecological disasters -- and find ways to forestall them. The project was suggested in 1987 by a study group led by Sally Ride, America's first woman in space.

- Mission to Planet Earth would go a long way toward answering critics who have insisted that the U.S. space program has for years had no clear mission. If NASA gets the go-ahead, the project, which would cost an estimated $20 billion over the next two decades, could begin by 1996 with the launching of the first of a pair of 15-ton unmanned space platforms called the earth- observing system (EOS). Designed to operate for at least 15 years, the satellites would give scientists their first comprehensive look at just how the world's environment changes over time. Detectors would monitor the shrinking of the tropical rain forests as well as of the polar ice caps (a possible consequence of global warming). One instrument would measure the stress of pollution on the leaves of trees, while another would monitor the health of small ponds. Data from all the detectors would be correlated in an unprecedented effort to understand the interactions of earth, sky and water.

But President Bush has not yet endorsed the program, and funding is uncertain. While NASA has $24.2 million of EOS start-up money in its fiscal 1990 budget, the big push for Mission to Planet Earth will begin this fall, when the agency asks for $100 million more for 1991. That hardly seems too much for a long-term commitment to help save the planet.