 Space Science |
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.
