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The Nimbus I satellite was launched from Vandenberg Air Force Base on August 28, 1964, using a Thor-Agena B launch vehicle. The project objectives were to provide improved photographs of local cloud conditions by an automatic picture transmission (APT) system, and to evaluate an advanced vidicon camera system for daylight coverage and a high-resolution infrared radiometer system for night-time cloud cover observation. Premature Agena cut off resulted in an elliptical orbit of 263 to 579 miles at an 80 degree inclination, rather than the intended circular orbit. The satellite's solar panel drive failed on September 23, after Nimbus had returned more than 27,000 excellent photos. The vidicon camera systems spotted five hurricanes and two typhoons in photographing 70 percent of the world each day. The APT system supplied daytime photos to more than 60 low-cost ground stations. Radiometer photos were remarkably clear and covered a 12,500 square mile area. A photo of the Antarctic taken at midnight showed four black dots determined as mountains at the edge of the continent. Further analysis indicated a strong possibility of volcanic activity in the mountains. Nimbus I's stabilization system worked well during its operational lifetime. NIMBUS II Nimbus II was launched from Vandenberg Air Force Base on May 15, 1966, by a TAT-Agena B launch vehicle. It was placed in a "high noon" retrograde orbit of 684 to 734 miles at a 100 degree inclination. Sun-synchronous orbit provides ideal lighting conditions for picture taking. The project objectives were to provide global weather photography on a 24-hour basis for meteorological research and operational use, and provide infrared data for study of earth's heat balance. Four sensor systems weighing a total of 142 pounds were carried. The advanced vidicon camera system (AVCS) included three 1-inch cameras with 800-line resolution designed to photograph a 800,000 square mile area. A high resolution infrared radiometer provided time and was expected to yield a variety of geophysical and atmospheric data including cloud height information. NIMBUS B Nimbus B was launched on May 18, 1968, from Vandenberg Air Force Base by an Air Force Thorad-Agena D launch vehicle. Two minutes after launch, a booster malfunction forced a command destruct by the safety range officer. The booster and spacecraft fell into the Pacific Ocean between Vandenberg Air Force Base and San Miguel Island off the coast of California. According to radar tracking, the closest point to shore where debris fell was 5 miles from Jalama Beach and 1 mile from San Miguel Island. The radioactive fuel for the two generators (plutonium 238) was contained in two high-strength alloy and graphite capsules, which had been designed and tested to withstand ocean impact and seawater corrosion in case of such an abort. Extensive tests have shown that under these conditions the fuel would present no hazard to people or marine life. NIMBUS III Nimbus III was launched from Vandenberg Air Force Base on April 14, 1969, by a Thorad-Agena D launch vehicle. Nimbus III was composed of three major elements: a 5-foot-diameter sensory section, a hexagonal upper section, and two 8-by-3-foot rotating solar panels. The upper and lower sections were connected by a truss structure. A sensory ring, a hollow circular section, contained all the weather-measuring experiments as well as spacecraft batteries, transmitters and associated electronic equipment. The stabilization and attitude control subsystem, housed in the upper section, was Earth oriented and stabilized within one degree on three axes. The satellite was 10 feet high and 11 feet across the solar panels. The weight of 1269 pounds was a heavyweight record for meteorological satellites. Nimbus III was a replacement for Nimbus B which was destroyed in a launch failure in May 1968. Nimbus III was to be the first United States satellite to make night and day global measurements from space of temperatures of the atmosphere, both over extended periods and, for the first time, at varying levels vertically. Obtaining such meteorological data, principally from over large bodies of water and marginally habitable land masses, and on such a scale, was to make possible experimental computerderived weather predictions, using mathematical models based on the scope of the numerical data Nimbus III would return. While meteorological objectives were primary, this mission also was to gather vital oceanographic data for scientific purposes other than solely for weather forecasting. Another mission objective was to provide data for the first experiment of the U.S.A. portion of the Global Atmospheric Research Program (GARP), which was an international program of formulating and coordinating research for achieving long-range global weather forecasting. Nimbus III was launched after two delays. One delay was caused by a propellant leak in the Agena, and the other was due to a launch priority at the range. The transmission of data from the seven meteorological experiments was as scheduled. All systems and payload functioned normally. NIMBUS IV The Nimbus IV satellite was launched from Vandenberg Air Force Base on April 8, 1970, by a Thorad-Agena D launch vehicle. It was placed in the planned, circular, near-polar orbit. It made world-wide weather observations twice a day - once in daylight and once in darkness. Nimbus IV was a continuation of the spacecraft series to serve as a testbed for research and development of new meteorological sensors, subsystems and systems configurations. Some of the technology developed in the Nimbus program was transferred to TIROS operational weather satellites. The meteorological objectives were to study spatial and temporal distribution of the atmospheric structure, particularly temperature, ozone, and water vapor, and to determine temporal variation in the solar radiation in the near ultraviolet. Nimbus IV was butterfly-shaped with a 5-foot diameter sensory ring lower section which housed experiments and supporting equipment. A hexagonal upper section contained the attitude control system. Two solar panels, 8 feet by 3 feet, provided more than 200 watts of power supplemented by two generators. The overall height was 10 feet; width was 11 feet. The orbital weight was 1366 pounds. NIMBUS E Nimbus E was launched from the Western Test Range, Vandenberg Air Force Base, on December 11, 1972, by a Delta 900 launch vehicle. It was a butterfly-shaped spacecraft with a 5-foot diameter ring lower section housing experiments and supporting equipment. A hexagonal upper section contained the attitude control system. Two solar panels provided more than 200 watts of power. The overall height was 10 feet; width was 11 feet. The three-axis stabilized spacecraft weighed 1580 pounds. Nimbus E was a continuation of development of new meteorological sensors, subsystems and systems configurations. It was an Earth-oriented platform for testing advanced systems collecting meteorological and geological data. NIMBUS F Nimbus F was launched from the Western Test Range, Vandenberg Air Force Base, on June 12, 1975, by a two-stage Delta 2910 launch vehicle. It was placed into a near-polar, circular orbit. A meteorological satellite, similar in design to other Nimbus satellites, Nimbus F weighed 1823 pounds. It was designed to test instruments for remote sensing of the Earth's atmosphere. NIMBUS G The Nimbus G satellite was launched from Vandenberg Air Force Base on October 24, 1978, by a Delta 2910 launch vehicle. It was placed in a circular, near-polar orbit with an inclination of 99.3 degrees and a period of 104 minutes. Similar to the other satellites in this series, Nimbus G was butterfly-shaped. Spacecraft and experiment data were transmitted to Earth stations immediately, or stored in an on-board high-speed tape recorder for subsequent playback when the satellite was in view of a ground acquisition station. Nimbus G was the first satellite to provide continuous, worldwide environmental data to help scientists throughout the world determine the physical characteristics of the global atmosphere, the oceans, the dynamic atmosphere-ocean interface, and the Earth's heat balance. For the first time, the European Space Agency (ESA) received and processed direct Nimbus G data at Lannion, France.