The perspective from space is a unique one, providing a global view that is available in
no other way. While scientists of the past were limited by the types of observations
available, today’s scientists use measurements collected from a number of perspectives.
Data from space-based instruments have become an integral tool for studying our
global environment. For example, remotely-sensed data indicating ocean temperature
helps explain changes in polar ice, ocean vegetation, and global weather patterns.
Global ozone measurements from space were the key to discovering the ozone hole.
Studies of ocean color provide information about ocean vegetation, pollution,
changes in ocean chemistry, and subtle changes in climate.
N A S A’s Mission to Planet Earth (MTPE) has evolved from international concern about
our environment and the need to mount a global eff o rt to study the causes of cli-
mate change. This program is dedicated to understanding the Earth system — how
the land, water, air, and life interact and how humans are affecting this system.
MTPE is pioneering the study of global climate change and is laying the foundation
for long-term environmental and climate modeling and prediction. MTPE is focusing
on climate changes—those changes that could occur on time scales of decades to
centuries—and possibly within our lifetimes.
This eff o rt involves gathering long-term global measurements of the Earth system using
spacecraft, aircraft, balloons, and ground-based observations. The gathered data is used
to build complex computer models that simulate the processes governing the Earth
system. These models will ultimately serve as prediction tools for future global changes,
p roviding information necessary for making informed decisions about the enviro n m e n t.
A number of MTPE satellites are collecting data. Two major research satellites are the
Upper Atmospheric Research Satellite (UARS) and the Ocean Topography Experiment
(TOPEX/ POSEIDON). UARS, launched September 1991, is investigating the Earth’s
upper atmosphere and the effects of human activities on stratospheric ozone levels.
Understanding the dynamics of ocean circulation and its role in climate change is the
main goal of TOPEX/POSEIDON, a joint eff o rt between NASA and the French Space
A g e n c y, launched in August 1992. Oceanographers are using data from TOPEX/
POSEIDON to study climatic phenomenon such as El Niño, a re c u rring event that
brings devastating weather to several global regions, including heavy rains and flood-
ing to California, colder than normal winters across the United States, and severe
d roughts and dust storms to Australia. Insights gained from the TOPEX/POSEIDON
investigation will not only advance our basic science knowledge, but will also aid in
mitigation of economic and environmental impacts related to climate.
The centerpiece of MTPE is the Earth Observing System (EOS). EOS will consist of a
series of small- to intermediate-sized spacecraft, planned for launch beginning in 1998.
These satellites will provide global measurements over an eighteen-year period.
Measurements for this period or longer are needed to assess the impact of natural
changes (e.g., El Niño events and the solar cycle) versus human-caused changes
(e.g., pollution, urbanization). EOS satellites will carry a suite of instruments designed
to study global climate change, focusing on the following key research areas: