Circling the Earth 16 times today 438 miles above the surface, new satellite technology is revolutionizing earth science and how scientists are able understand the health of the planet and distinguish between human impact and natural phenomenon. On February 4, scientists began collecting images of the earth's vital signs from its bus-sized Terra satellite, the flagship of NASA's 15-year Earth Observing System (EOS). EOS is an international collaboration designed to help scientists develop those answers about Earth's climate and environmental changes that have not been available before. The first images from Terra range from Japan's active Mt. Usu volcano and San Francisco's urban environment to the pollution over India and plant life in the Arabian Sea.
This animation shows the earth's weather systems driven by the distribution of energy measured by the CERES device on Terra. Such images are giving rise to the new revolution in earth science. (Courtesy: NASA)
Though the earth is approximately 4.5 billion years old, the earliest ancestors of the human race only appeared between three and four million years ago, according to most scientists. This is only one-tenth of one percent of Earth's time span, a relatively insignificant period. Even the first known civilization did not appear until about 6,000 BC. But since the dawn of humankind, the earth supplied all of their wants and needs, which led to settled life in groups or villages. Yet during the entire lifespan of the earth, natural geologic forces have constantly been changing and rearranging the planet's features, climate and environment. And now, there is "compelling evidence that human activities have attained the magnitude of geological force and are speeding up the rates of global change," according to Dr. Yoram Kaufman, Terra Project Scientist. According to Dr. Kaufman, these changes have occurred without much knowledge at all about their impact on earth's life systems. "Scientists don't understand the cause-and-effect relationships among Earth's lands, oceans, and atmosphere well enough to predict what, if any, impacts these rapid changes will have on future climate conditions," he said.
This image from Terra shows chlorophyll concentrations and phytoplankton health in the Arabian Sea via it's MODIS instrument. Courtesy: NASA)
"There are some basic questions about the Earth system that need to be answered in order to understand our world's climate system well enough to predict future changes, and how those changes may impact our quality of life," said Dr. Kaufman during a recent NASA news briefing in Washington, DC. "Terra data, along with other measurements, will feed earth science models so we can predict climate variations and climate change, and prepare for the future. "We anticipate that Terra data will revolutionize our understanding of the Earth's climate system and help show the human impact," he continued. "Terra is measuring a wide array of vital signs, many of them for the first time, to help us understand our planet, to distinguish between natural and man-made climate change, and to show us how the Earth's climate affects the quality of our lives."
Dr. Kaufman describes that this revolution in earth science is necessary to help in the understanding of our world's climate systems enough to accurately predict changes and how those changes will impact quality of life. Questions which need to be answered include:
How are the soils and vegetation types changing around the world?
What are the changes in the extent of snow and ice, and why are 2-3 of the world's glaciers disappearing each week?
What are the variations in the phytoplankton in the ocean and how are these plants affected by windblown Saharan dust?
What is the concentration of atmospheric airborne particles and gaseous pollutants, and how do they affect the ability of the atmosphere to cleanse itself?
What fraction originates from natural or man-made sources?
How does the availability of water vapor and the presence of pollutants affect cloud formation, properties and precipitation?
Is the Earth system taking in more radiant energy than it reflects and emits back into space, or is the radiation budget in balance (global warming)?
Is there a change in the frequency of wild fires, floods, & volcanic eruptions? Is the frequency related to climate change?
The Terra observatory uses five instruments to thoroughly study and track Earth's vital systems: Land, Ocean, Atmosphere, and the life, exchange of nutrients, carbon, heat, moisture and pollution among them. The first instrument is called the Moderate-resolution Imaging SpectroRadiometer (MODIS). MODIS provides frequent global views of changes occurring within the Earth system, including the study snow and ice cover, cloud cover and cloud type, vegetation cover and other land covers, the temperature of the oceans, and the study of plant life on land and in the oceans.
This thermal infrared image shows the urban heat island effect in the San Francisco Bay area through Terra's ASTER instrument(Courtesy: NASA)
The second instrument is the Multi-angle Imaging SpectroRadiometer (MISR) physically characterize the Earth's surface, atmosphere, and clouds, and how they interact with sunlight, the primary energy source for Earth's climate system. The third instrument, the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) is a joint US-Japan project provided by Japan's Ministry of International Trade and Industry. It is the zoom lens of the Terra satellite. The primary goals of ASTER are to characterize the Earth's surface and to monitor dynamic events and processes that influence habitability at human scales. The Measurements of Pollution in the Troposphere (MOPITT) is a fourth instrument that helps scientists determine the amount of carbon monoxide and methane at different altitudes in the atmosphere. MOPITT is a joint effort of the US and Canada.
The final instrument is called Clouds and the Earth's Radiant Energy System (CERES) which measures reflective sunlight. Measuring the energy emitted by the surface and atmosphere of the Earth, CERES monitors the balance of the "radiation budget" which indicates whether the earth is warming or cooling. If the radiation budget if perfectly balanced, the earth should neither be warming nor cooling.
