Lockheed Martin Space Systems Company of Sunnyvale, Calif., built the spacecraft. The instruments onboard NOAA-M include the Advanced Very High Resolution Radiometer/3; the High Resolution Infrared Radiation Sounder/3; the Advanced Microwave Sounding Unit-A1, A2; the Advanced Microwave Sounding Unit-B; the Solar Backscatter Ultraviolet Radiomete/2; the Space Environment Monitor/2; and the Data Collection System/2. In addition, it carries two search and rescue instruments: the Search and Rescue Repeater and the Search and Rescue Processor.

Illustration of the NOAA-M spacecraft. Photo: NASA/NOAA

For over 30 years, NOAA has freely and openly provided satellite data through direct broadcast to users in the United States and in 100 other countries throughout the world. In the United States, any commercial firm receiving data through direct readout may provide tailored products to customers and/or viewers. In addition, polar operational environmental satellite data products are made available to users in the United States and throughout the world through NOAA's Satellite Active Archive.

The NOAA polar operational environmental satellites collect global data on cloud cover; surface conditions such as ice, snow, and vegetation; atmospheric temperatures; and moisture, aerosol, and ozone distributions; and collect and relay information from fixed and moving data platforms.

The Advanced Very High Resolution Radiometer/3 is the primary imaging system and consists of visible, near infrared (IR) and thermal IR channels. The primary sounding suite flying on NOAA-M is the High Resolution Picture Transmission/3, Advanced Microwave Sounding Unit-A and Advanced Microwave Sounding Unit-B, which measure atmospheric temperature and humidity. The Solar Backscatter Ultraviolet Radiometer/2 instrument is both an imager and a sounder. As an imager, it produces total column ozone maps. As a sounder, it obtains and measures the ozone distribution in the atmosphere as a function of altitude.

The Advanced Very High Resolution Radiometer/3, built by International Telephone and Telegraph-A/CD (Fort Wayne, Ind.), is composed of six detectors: three view reflected energy in the visible portion of the electromagnetic spectrum and three view energy in the near-infrared portion of the electromagnetic spectrum. The Advanced Very High Resolution Radiometer (which is the type of instrument called an 'imager') observes vegetation, clouds, and the surface of bodies of water, shorelines, snow, aerosols and ice. It can detect the heat in the environment, the temperature of snowcaps and the sea surface, vegetation growth around the world and forest fires. From this data, scientists on the ground can determine whether snowcaps are growing or diminishing in size, the effects of changes in ocean temperature and other changes in the environment. The instrument has a scan mirror that continuously rotates and scans the Earth at six revolutions per second to provide continuous coverage. The data generated by the Advanced Very High Resolution Radiometer is used worldwide by scientists, commercial fisherman, teachers and many others.

The High Resolution Picture Transmission/3, built by ITT-A/CD, is an atmospheric sounding instrument. It observes 'columns' in the atmosphere and obtains data from each of 20 segments (or bands) in that column. Each of these 20 bands can be associated with energy from a specific region and height in the atmosphere. By combining the data from the different bands, the instrument can generate complete temperature and moisture profiles. It can also measure how much of the Sun's energy remains as it travels through the atmosphere. The instrument has 19 infrared channels and one visible channel. Each channel takes measurements at a particular frequency that is associated with a particular element (or gas) in the atmosphere. These gases are principally carbon dioxide, water and ozone. These measurements allow scientists to determine the amount of each of these gases in the atmosphere and the altitude at which they appear.

High Resolution Picture Transmission/3 is used along with the Advanced Microwave Sounding Unit instruments to produce atmospheric temperature, humidity and total ozone profiles from the Earth's surface to about 40 kilometers (23.3 miles) altitude. The data is also used to determine ocean surface temperatures, precipitable water, cloud height and coverage and surface radiance. The instrument completes one scan every 6.4 seconds.

The Advanced Microwave Sounding Unit-A1,-A2, built by Aerojet (Azusa, Calif.) provides data that is used along with data obtained from the High Resolution Picture Transmission to produce a new suite of microwave-based surface and hydrological products, including global atmospheric temperature and humidity profiles from the Earth's surface to the upper stratosphere, about 48 kilometers or 29.8 miles. Among these products are total precipitable water (water vapor), cloud liquid water, rain rate, snow cover and sea ice concentration, It has 15 channels and continuously scans the Earth's surface and the atmosphere, measuring naturally emitted microwave signals radiated by the Earth's surface and atmosphere. The microwave signals measured by the Advanced Microwave Sounding Unit-A range from 23 gigahertz to 89 gigahertz. The Advanced Microwave Sounding Unit-A is divided into two physically separate modules, each of which operates and interfaces with the spacecraft independently.

The Advanced Microwave Sounding Unit -B, built by British Aerospace (Bristol, England) for the United Kingdom Meteorological Office, allows the calculation of vertical water vapor profiles from the Earth's surface to about 12 kilometers or 7.5 miles from the Earth's surface. It has five channels and continuously scans the Earth's surface and the atmosphere, measuring microwave signals radiated by the Earth's atmosphere. The Advanced Microwave Sounding Unit-B measures microwave signals from 89 GHz to 183 GHz.

The Solar Backscatter Ultraviolet Radiometer/2, built by Ball Aerospace (Boulder, Co.) is flown on the NOAA afternoon satellites. It is a long-term monitoring device that takes global measurements and observes how elements in the atmosphere change over time. The Solar Backscatter Ultraviolet Radiometer uses its 12 channels to measure the amount of radiation (or energy) that comes directly from the Sun (using a diffuser) and how much energy is reflected back from the Earth. This information is integrated into a scientific model that calculates the concentration and distribution of ozone in the stratosphere. However, the primary use of the data from the Solar Backscatter Ultraviolet Radiometer is determining the vertical distribution of ozone over the global surface - how it varies at various distances from the Earth's surface up to approximately 79 kilometers (or 49 miles). The instrument also provides for the generation of layer ozone values, which represent the amount of ozone found in a 'chunk' of the atmosphere.

Each channel on the Solar Backscatter Ultraviolet Radiometer detects a particular near-ultraviolet wavelength whose intensity depends on the ozone density at a particular height in the atmosphere. It is nadir pointing, which means that it always points directly toward the center of the Earth and does not scan the atmosphere as the other POES instruments do. The Solar Backscatter Ultraviolet Radiometer has a device called a Cloud Cover Radiometer that provides information on the amount of cloud cover in an image and removes the effects of the clouds from the data.

The Space Environment Monitor/2, built by Panametrics (Boston, Mass.) for the NOAA Space Environment Center, detects charged particles and provides measurements to determine the intensity of the Earth's radiation belts and the flux of charged particles into the atmosphere at the satellite's altitude. It provides knowledge of solar terrestrial phenomena and also warns of solar storms that may impair long-range communication and high-altitude operations, damage satellite circuits and solar panels, or cause changes in drag and magnetic torque on satellites. The instrument consists of two separate sensor units and a common Data Processing Unit. The sensor units are the Total Energy Detector and the Medium Energy Proton and Electron Detector.

The Search and Rescue instruments on-board NOAA-M consist of a Search and Rescue Repeater built by Department of National Defense in Canada and a Search and Rescue Processor built by Centre National d'Etudes Spatiales (Touluse, France). These instruments detect distress calls sent from emergency beacons on-board aircraft and boats and carried by people in remote areas. The instruments on the spacecraft transmit the data to ground receiving stations or local user terminals where the location of the emergency signals is determined by Doppler processing. The Local User Terminals forward the information to a Mission Control Center where further processing of the information occurs. The information is then sent to a Rescue Coordination Center that affects the search and rescue.

Illustration of the Search and Rescue network. Photo: NOAA

Since its inception in 1982, the COSPAS-SARSAT system has contributed to saving more than 10,000 lives. The Search and Rescue Repeater accepts signals from emergency ground transmitters at 121.5 MHz, 243 MHz and 406.05 MHz and uptranslates, multiplexes and transmits these signals at L-band to the local user terminals. The Search and Rescue Processor is a receiver and processor that receives 406.05-MHz signals from emergency ground transmitters and demodulates, processes, stores and relays the data to the next local user terminal that is within range of the Search and Rescue Repeater.

The Data Collection System provided by CNES in France measures environmental factors such as atmospheric temperature and pressure and the velocity and direction of the ocean and wind currents. Data is collected from transmitting devices on platforms in the form of buoys, free-floating balloons and remote weather stations. Transmitters are even placed on migratory animals, sea turtles, bears and other animals. Data is transmitted to the spacecraft for storage and subsequent transmission from the satellite to the ground. The stored data is transmitted once per orbit. Subsequently, the data is sent to the French Centre at the Centre National D' Etudes Spatiales and the Service Argos Facility in Lanham, Md., for processing, distribution to users and storage for archival purposes.