Weather forecasting At the time of its launch, the idea that intangible properties such as
air pressure could be observed using a satellite orbiting hundreds of miles above the Earth was revolutionary. With each Nimbus mission, scientists broadened their ability to collect
atmospheric characteristics that improved
weather forecasting, including ocean and air temperatures, air pressure, and
cloudiness. Beginning with the Nimbus 3 satellite in 1969, temperature information through the atmospheric column began to be retrieved by satellites from the eastern Atlantic and most of the Pacific Ocean, which led to significant forecast improvements. The global coverage provided by Nimbus satellites made accurate 3–5 day forecasts possible for the first time. The ability of the Nimbus satellites to detect
electromagnetic energy in multiple
wavelengths (multi-spectral data), in particular the
microwave region of the
electromagnetic spectrum, made it possible for scientists to look into the atmosphere and tell the difference between
water vapor and liquid water in clouds. In addition, they were able to measure atmospheric temperature even in the presence of clouds, a capability that allowed scientists to take the temperature in the "warm core" of
hurricanes.
Radiation budget One of the most important scientific contributions of the Nimbus missions was their measurements of the Earth's
radiation budget. For the first time, scientists had global, direct observations of the amount of solar radiation entering and exiting the Earth system. The observations helped to verify and refine the earliest climate models, and are still making important contributions to the study of
climate change. As scientists consider the causes and
effects of global warming, Nimbus radiation budget data provide a base for long-term analyses and make change-detection studies possible. The Nimbus technology gave rise to current radiation-budget sensors, such as the
CERES instruments on NASA's
Terra and
Aqua satellites.
Ozone layer Even before the Nimbus satellites began collecting their observations of Earth's
ozone layer, scientists had some understanding of the processes that maintained or destroyed it. They were pretty sure they understood how the layer formed, and they knew from laboratory experiments that
halogens could destroy
ozone. Finally,
weather balloons had revealed that the concentration of ozone in the atmosphere changed over time, and scientists suspected weather phenomena or seasonal change were responsible. But how all of these pieces of information worked together on a global scale was still unclear. Scientists conducted experiments from NASA experimental aircraft and proved that atmospheric chemicals such as the
chlorofluorocarbons (CFCs) released from
refrigerants and
aerosol sprays did destroy ozone. As Nimbus 7 satellite observations accumulated between 1978 and 1994, it became increasingly clear that CFCs were creating an
ozone hole each winter season over
Antarctica. Not only that, but despite some year-to-year variations, it appeared the hole was becoming larger. The Nimbus measurements made clear how severe the ozone hole problem was.
Sea ice Nimbus satellites collected orbital data on the extent of the polar caps in the mid-1960s, recorded in the visible and infrared parts of the spectrum. These first global snapshots of Earth's icecaps provide invaluable reference points for climate change studies. During a narrowing window of opportunity for
data archaeology, the
National Snow and Ice Data Center (NDISC) and NASA were able to recover data that allowed the reconstruction of high-resolution Nimbus 2 images from 1966 showing the entire Arctic and Antarctic ice caps. When the Nimbus 5 spacecraft launched in 1972, scientists planned for its
Electrically Scanning Microwave Radiometer to collect global observations of where and how much it rained across the world. However, a new priority for the sensor evolved in the months following its launch: mapping global
sea ice concentrations. When Nimbus 7 launched in 1978, technology had improved enough for scientists to distinguish newly formed (i.e., "first year") sea ice from older ice, with the
Scanning Multichannel Microwave Radiometer (SMMR) sensor. The data it collected during its 9-year lifespan provide a significant chunk of the long-term record of Earth's
sea ice concentration that today's scientists use for studies of climate change. Among the most serendipitous discoveries that the Nimbus missions made possible was that of a gaping hole in the sea ice around Antarctica in the Southern Hemisphere winters of 1974–76. In a phenomenon that has not been observed since, an enormous, ice-free patch of water, called a
polynya, developed three years in a row in the seasonal ice that encases Antarctica each winter. Located in the
Weddell Sea, each year the polynya vanished with the summer melt, but returned the following year. The open patch of water may have influenced ocean temperatures as far down as 2,500 meters and influenced ocean circulation over a wide area. The Weddell Sea Polynya has not been observed since the event witnessed by the Nimbus satellites in the mid-70s.
Global positioning system Nimbus satellites (beginning with Nimbus 3 in 1969) blazed the trail into the modern
GPS era with operational
search and rescue and data collection systems. The satellites tested the first technology that allowed satellites to locate weather-observation stations set up in remote locations and to command the stations to transmit their data back to the satellite. The most famous demonstration of the new technology was through the record-breaking flight of British aviator
Sheila Scott, who tested the Nimbus navigation and locator communication system when she made the first-ever solo flight over the
North Pole in 1971. The Nimbus ground-to-satellite-to-ground communication system demonstrated the first satellite-based search and rescue system. Among the earliest successes were the rescue of two
hot air balloonists who went down in the
North Atlantic in 1977 and, later that year, tracking a
Japanese adventurer on his first attempt to be the first person to
dogsled solo to the North Pole through
Greenland. Tens of thousands of people over the past three decades have been rescued through the Search and Rescue Satellite-aided Tracking (
SARSAT) operational system on NOAA satellites.
Nuclear power Nimbus-3 was the first satellite to use a
SNAP-19 radioisotope thermoelectric generator (RTG) in space. A previous attempt was made to launch a SNAP-19 RTG on Nimbus-B-1, but the rocket was destroyed and the nuclear fuel landed in the
Santa Barbara Channel. Later, the fuel was recovered from the wreckage at a depth of and re-purposed for Nimbus-3 as the SNAP-19B. This power source augmented the solar array with an additional of electrical power. ==Operation history of the Nimbus satellites==