Mission to Planet Earth
Planet Earth is in a constant state of change. Scientists
understand some of the changes fairly well-weather in the short
term, for example, or hurricane tracking, or how things grow.
But they lack a lot of critical information, such as the kind
of data needed to predict how the climate will shift a year hence
and how the shift will affect farmers, water managers, fishermen
and others whose livelihoods depend on climate.
This is a visualization of the Antarctic ozone hole, computer-generated
from data supplied by NASA's Total Ozone Mapping Spectrometer.
The colors represent different ozone levels over the Antarctic;
the purple area in the center is the "hole," an area
where the ozone has disappeared.
That need is being met by a coordinated,
U.S.-led international research program designed to reduce the uncertainties
of global change. The United States has established the U.S. Global Change
Research Program. NASA's part of the program is the Mission To
Planet Earth (MTPE), a program that employs satellites and other
tools to generate data about such areas of environmental concern
as ozone depletion, deforestation, climate variability, earthquakes,
volcanoes and destructive storms, and the ocean-influenced phenomenon
known as El Niño.
MTPE studies are expected to yield improved weather forecasts,
tools for managing forests and agriculture, information for fishing
fleets and coastal planners, and-eventually-an ability to predict
how the climate will change.
Weather satellite imagery is contributing to a capability
to predict weather events and initiate measures to prevent loss
of life from destructive storms. This is an image supplied by
the GOES-8 satellite of Hurricane Luis in September 1995; the
white area shows the hurricane's high wind swirl as it moves
over the Gulf of Mexico (blue) toward the Louisiana/Florida gulf
coast (green).
Phase I of the MTPE program has been under way since September
1991. Among the major contributors are the Upper Atmosphere Research
Satellite, which is investigating the role of the upper atmosphere
in climate and climatic change; the Shuttle-based Space Radar
Laboratory, which has provided extensive data for studies of
how shifting boundaries between temperate and boreal (northern)
forests might affect climatic change; and the Total Ozone Mapping
Spectrometer, an instrument flown on several U.S. and international
spacecraft to study ozone depletion.
A prime contributor has been the U.S./French oceanographic
satellite TOPEX/Poseidon, which precisely measures wave height
and changes in average sea level. TOPEX/Poseidon reported rising
sea levels over each of the past three years; though not sufficient
to determine a trend, the findings are important to understanding
how the oceans interact with other Earth phenomena.
In a related discovery, TOPEX/Poseidon observations, combined
with data from other sources, led to ground-breaking findings
about the El Niño phenomenon. No one knows why El Niño
occurs, but reports show it has been happening for hundreds of
years, profoundly affecting weather patterns and causing floods
and drought in various parts of the world. TOPEX/Poseidon data
helped scientists predict El Niño more than a year in
advance, enabling those potentially affected to alter crop plans
and planning for other activities.
The TOPEX/Poseidon oceanographic satellite has been a major
contributor to NASA's Earth studies. It employs a sensitive altimeter
to measure sea surface heights and compute average sea levels,
information that helped enable advance prediction of the El Niño
phenomenon.
Additionally, NASA-developed weather satellites operated by
the National Oceanic and Atmospheric Administration are contributing
to a growing mosaic of Earth knowledge by providing an advanced
observational/predictive capability that allows planning for
upcoming weather events and initiation of measures to prevent
loss of life from hurricanes and other destructive phenomena.
In 1997, MTPE will probe new areas with the launch of SeaStar,
a privately-developed spacecraft designed to provide NASA with
data on life in the oceans (data which may also be marketable
to the fishing, oil and shipping industries), and with a joint
NASA/Japan mission to study tropical rainfall, which is poorly
understood but an essential element in the global climatic change
equation.
The year 1998 will mark the beginning of Phase II of the Mission
To Planet Earth program, which will feature the first integrated
measurement of changes in global climate and will provide practical
information to enhance the efficiency of business, farming, fishing
and forestry operations.
A key tool of Phase II will be the Earth Observing System
(EOS). Employing a number of different satellites, EOS will look
at Earth in an entirely new way: rather than focusing on only
one aspect (land, ocean, air), EOS satellites will observe multiple
aspects of the planet. The broader range of information acquired
will enable scientists to study interactions among Earth phenomena
and allow them to move beyond a description of what is happening
to and understanding of why it is happening.
EOS AM-1, to be launched in 1998, will look at Earth in a
new way: where earlier spacecraft observations focused on specific
aspects of the global environment, EOS satellites will enable
the first long term comprehensive measurements of how components
of the Earth system interact.
EOS is the first system designed specifically to study the
Earth as a complex series of interactions among life, air, water
and land, the critical next step toward understanding and predicting
the complexities of the global climate. EOS will contribute to
such understanding by observing in 24 measurement areas which,
a consensus of scientists believes, can supply answers to many
of the complex questions about global climate change. Over a
15-18 year period, EOS satellites will fly over most of Earth's
surface, gathering data on such matters as global climate changes
in the atmosphere, land surface changes, pollution and water
resources. What were previously studied as a series of isolated
events will be examined as interconnected/interactive forces
to form a snapshot of Earth as a whole.
The work of the EOS satellites will be complemented by a new
family of spacecraft known as the Earth Systems Science Pathfinder
(ESSP), a series of small, low-cost, rapid development science
missions (life cycle cost will be capped at $120 million and
development time will be held to 24-36 months). The ESSP satellites
will incorporate the latest Earth observation technologies and
will involve new contracting approaches and partnerships with
industry. The first ESSP launch is targeted for 1999 and there
will be one launch a year thereafter.
Slated for launch in 1998 is the EO-1 advanced land imaging
spacecraft, the first Earth observation spacecraft of NASA's
New Millennium Program, which features a revolutionary series
of small, low-cost satellites. EO-1 will focus on demonstrating
advanced technologies for future Earth observation missions.
Another innovative NASA program, the New Millennium Program
(NMP), will play a part in the Mission To Planet Earth. A coordinated
NASA/industry activity incorporating next generation technologies,
such as lightweight low-cost instruments, NMP focuses on demonstration
of technologies and techniques for improving the performance
and lowering the cost of future NASA missions. The first MTPE
mission of this type will be the flight of EO-1, an advanced
land imager to be launched in 1998. EO-2 is planned to follow
18-24 months later and there will be about one launch a year
thereafter.
The MTPE program, which is generating an enormous and ever-increasing
flow of data, clearly requires a highly advanced data processing
system to analyze and move data from the many U.S. and foreign
spacecraft to governments, scientists, educators, businesses
and the general public. For that purpose, NASA operates an information
system known as EOSDIS (Earth Observing System Data and Information
System). As the amount of data and the number of people using
the system increase, EOSDIS will evolve and expand, taking advantage
of the latest technological advances to maintain the quality
and timeliness of information dissemination; thousands of users
around the world will be able to access EOSDIS at the same time.
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