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Guest Writer: Dr. Mitchell K. Hobish, Consultant

Overview of MPTE and EOS; Global Changes

It was probably when Apollo astronauts, on the way to the Moon, first saw our home planet in its entirety from their unique vantage point in space that humans began to view Earth as a single entity, rather than a conglomeration of diverse political entities . To this day, astronauts on their first flights all note the absence of "painted" national boundaries, as they look down upon Earth from orbit. Instead, land, oceans, and clouds dominate the view.

Color photograph of the Earth.

16-1: Look closely at this rather dark view of some part of Earth. What continent(s) are visible? ANSWER

To the best of our knowledge, Earth is the only planet in the Solar System that supports life (although organic molecules may exist on one or more satellites of Jupiter and Saturn, and perhaps once on Mars. See Section 19). Life, in all its myriad forms, virtually covers Earth. No matter where we look for it, we find it. Much of our planet's geophysical and biological phenomena take place in a relatively thin shell of fluid (the atmosphere and oceans) that is about as thin in proportion to the Earth as a sheet of paper wrapped around a basketball. Most other relevant life activities stay on the land surface,within an even thinner zone of the uppermost layers of soil and rock. And yet, the complex interactions between the biosphere and the geosphere all take place within that thin shell. Just about everything that concerns us as living beings depends upon the integrity of these shells of land, sea, and air.

16-2: Can you think of any place (or condition) at the Earth's surface where life is not to be found? ANSWER

The shells result from eons of dynamic processes that began as the Earth formed. These processes, taken together, constitute global change. Without global change, we humans and much of the rest of the biosphere would not exist, because global change generated an oxygen-containing atmosphere, our protective stratospheric ozone layer, and global temperatures that support life (due to the greenhouse effect) as we know it. Until the last few thousand years, global change has been dominantly a "natural" process.

Recent observations have led scientists to conclude that human activities contribute to global change, that our industrial and land-management practices increase the rate of change of several geophysical phenomena, and that some changes may be deleterious to the biosphere. Nations around the world have banded together in a wide range of scientific and policy-based activities to determine the nature of human contributions to global change and to determine the effect such changes can have on our lives. These are gathered under the umbrella known as the International Geosphere-Biosphere Program (IGBP), which is, in essence, a massive effort to understand and learn to manage the world's environments.

16-3: Think of at least three such vital phenomena whose change can be directly traced to Man's activities. ANSWER

As one of several U.S. government agencies involved in the U.S. Global Change Research Program, NASA has instituted the Mission to Planet Earth (MTPE) (on the Net at MTPE), based on the space-based constellation of satellites and sensors known as the Earth Observing System (EOS). This section deals with some of the observations obtained in recent years that have led to the formation of MTPE/EOS, why NASA established it, what NASA designed it to accomplish, how NASA approaches those goals, and what anyone can do with the data.  .  For some general information about this and related programs, click on NASA's Earth Observatory Home Page.


* Mitchell K. Hobish, Consulting Synthesist, prepared this unit , with some additions by N.M. Short

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Primary Author: Nicholas M. Short, Sr. email:

Collaborators: Code 935 NASA GSFC, GST, USAF Academy
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