The Earth Observing System (EOS) is a NASA program that uses satellites and scientific tools in space to study Earth over long periods. These tools observe Earth's land, living things, air, and oceans. NASA began working on this program in the 1970s, launching the first Landsat satellites during that time. One of the earliest tools was the Nimbus 5 satellite, which used passive microwave imaging in 1972. The idea for the program started in the late 1980s and grew quickly during the 1990s. Since it began, the program has expanded to study land, sea, radiation, and the atmosphere. Data from these studies is collected in a system called EOSDIS. NASA uses this data to learn about changes in Earth's living things. The main goal is to understand climate science. EOS is the main part of NASA's Earth Science Enterprise.
History and development
Before the creation of the current Earth Observing System (EOS), the program's beginnings were in the early 1960s and 1970s. TIROS-1 was the first complete, low Earth orbit weather satellite. Its main goal was to test television infrared observation as a way to monitor and study Earth's surface. TIROS-1 was important for the development of today’s satellites because it allowed NASA to test new tools and methods for studying weather worldwide. The information gathered by TIROS-1 helped scientists observe large weather events, such as hurricanes, and answer questions like, "Should people leave the coast because of a hurricane?" After TIROS-1, the Applications Technology Satellite (ATS) program was created. These satellites focused on predicting weather and studying space environments. A key part of this program was launching satellites into geosynchronous orbit to test how well this orbit could observe Earth. ATS-3, the longest mission, operated for over 20 years. It was the first satellite to take color images from space and played an important role in communication.
After the success of TIROS-1 and ATS-3, NASA worked with the United States Geological Survey (USGS) to advance Earth observation through a series of Landsat satellites launched in the 1970s and 1980s. The Nimbus 5 satellite, launched in 1972, used passive microwave imaging, a successful method for observing changes in sea ice. Later missions, such as Nimbus 7, included tools like the coastal zone color scanner (CZCS) to study ocean color changes and the Total Ozone Mapping Spectrometer (TOMS) to measure sunlight and light reflected from Earth’s atmosphere. Early satellites from these programs helped create the basis for today’s EOS program. TIROS satellites were vital for testing Earth observation tools like spectrometers. Scientists also learned how to use sensors, such as horizon sensors, to keep satellites in orbit for longer periods. These sensors were later improved to create more advanced observation methods and satellite operations.
Data collection and uses
Since the program began, its main goal has been to "monitor and understand important parts of the Earth's climate system and how they work together through long-term observations around the world." Scientists use tools like the LandSat and A-Train programs to learn more about Earth and how it changes over time. Today, data from satellites in the Earth Observing System (EOS) is converted into digital form and organized by the Earth Observing System Data and Information System. Scientists use this data to predict weather events and, more recently, to study the effects of climate change for agreements like the Paris Climate Agreement. Most of this data comes from EOS and is then analyzed.
Intergovernmental agencies and partnerships
In a larger view of Earth observation and all missions related to the Earth Observing System (EOS), many partnerships between different governments and countries have helped fund, research, and create the satellites and spacecraft that support the EOS. These partnerships include intergovernmental agreements, which make up about 37% of all missions, and international partnerships with other countries and companies, which account for 27% of all missions.
As of 2022, there have been nine Landsat satellites, with Landsat 7, 8, and 9 currently orbiting Earth. The Landsat program has involved many organizations since it began, especially the United States Geological Survey (USGS). Other government agencies that have participated in the Earth Observing program include the Environmental Science Services Administration (ESSA), the U.S. Department of Defense (USDOD), the U.S. Department of Energy (USDOE), and the U.S. National Oceanic and Atmospheric Administration (NOAA). These partnerships allow for more funding and the sharing of resources from different government agencies. Often, these partnerships start when one government agency requests a specific instrument to be included in a mission’s payload.
International partnerships with other countries have also been important. These partnerships sometimes happen when a specific instrument is added to an existing NASA mission or when NASA works with another space agency, such as the European Space Agency, to use their facilities. For example, in 2000, the ERS-1 satellite was launched from the Guiana Space Centre, a spaceport in French Guiana, South America. International space agencies that have worked with NASA include CONAE (Argentina), CNES (France), DLR (Germany), Roscosmos (Russia), and JAXA (Japan, formerly NASDA).
Throughout the program’s history, partnerships with companies and organizations in the United States and other countries have also been important. In 2002, the SeaWIFS mission included a collaboration with GEOeye, an American satellite imaging company. Organizations such as the International Council for Science (ICSU), International Standards Organisation (IOS), World Data System (WDS), and the Committee on Earth Observing Satellites (CEOS) have also helped with planning, collecting data, and analyzing data from missions. These partnerships provide benefits such as funding, adding important tools, and helping with coordination and data analysis.
Future missions
The Earth Observing System is becoming more important for studying Earth's climate and changes. NASA and other groups, like the European Space Agency and NASDA in Japan, are planning future missions. One of these is Sentinel 6B, which will continue observing water and oceans. A main goal of the Sentinel missions is to track rising sea levels, which show how Earth's climate is changing. As more countries work to reduce carbon emissions, data from Sentinel missions will help scientists understand climate changes better. One Sentinel satellite will also test a new method called Global Navigation Satellite System Radio Occultation (GNSS-RO), which uses satellite signals to study the atmosphere's layers.
The Joint Polar Satellite System (JPSS) is expected to launch in 2027. This project is a partnership between NASA and NOAA to build new polar-orbiting environmental satellites. These satellites will not stay above the same spot on Earth, as their orbits will be at an angle close to 90 degrees from the equator. This is the third and fourth satellite in the JPSS series. These satellites will carry tools like the Visible Infrared Imaging Radiometer, Advanced Technology Microwave Sounder, and Ozone Mapping and Profiler Suite. The data collected will help improve weather predictions and climate models.
The Investigation of Convective Updrafts (INCUS) mission, part of the Earth Venture Missions, plans to launch three small satellites. These satellites will work together to study how convective storms and heavy rain form. Scientists want to know not only how storms develop but also where and when they will occur. The first satellite is planned for 2027. After reviewing 12 proposals in 2021, the INCUS mission was chosen. NASA's Earth Science Director, Karen St. Germain, said, "Better information about how storms form and grow can improve weather models and help predict extreme weather risks." As global sea temperatures rise due to climate change, storms are expected to become stronger and more frequent. This happens because more water vapor rises, creating stronger air currents. INCUS will help scientists study these currents and predict where major storms might happen.