NASA (National Aeronautics and Space Administration) is a US government agency, that's responsible for civilian research in aerospace and aeronautics. Besides spearheading all the best space research programs till date and putting man on the Moon, NASA is actively involved in launch of satellites aimed at studying the various features of its mother planet. Dedicated to future of space exploration, NASA is also invested in more 'Down-to Earth' projects, through its space program.
It strives to improve economic efficiency all over the world, by issuing the weather data and images for analysis, besides increasing our awareness towards the scope of hazards such as storms, hurricanes and other weather threats. The NASA satellite program has succeeded in generating awareness and warning the international community about impending weather-related dangers through detailed satellite imagery. Central to this aspect of NASA's mission is the 'Earth Observation System', consisting of satellites launched with the aim of studying our planet's land mass, biosphere, oceans and atmosphere in great detail. In this UniverSavvy article, we review NASA's satellite imagery.
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Image courtesy NASA
Image courtesy NASA
Importance of NASA Satellite Images
NASA has a number of 'eyes' in the sky, in the form of satellites, which unblinkingly observe Earth in the visible, infrared and other electromagnetic wavelengths, to provide us with a wealth of information about every phenomenon active on the planet.
Specially designed Earth observation satellites are equipped with high resolution cameras and various types of sensors, which collect data and transmit it down to Earth to base stations for processing. Be it an impending Tsunami scare, a hurricane or an environmental catastrophe, NASA's satellite imagery has helped create an effective warning system, that has saved thousands of lives.
The satellite images help governments and rescue operators all over the world in accessing important navigation routes. They also help in measuring and recording changes in vegetation and observe the atmosphere. The satellites that offer dedicated images and information on the atmosphere are classified as weather satellites. These satellites provide world citizens with vital weather forecasts. Besides weather forecasting, on board instruments include sensors that can make global measurement of cloud cover, water vapor, snow cover, rainfall, sea surface temperature, land surface temperature and carbon monoxide distribution. In short, all the critical environmental variables are now measurable using satellites and this technique is known as 'Remote Sensing'. Besides this, high resolution satellite photographs provide a roving eye, that can help reveal the surface details of any geological location on the planet.
How are NASA Satellite Images Generated?
NASA satellite photos are generated with the intent of creating an imaging network for even the most inhospitable regions on land and oceans. The horizontal, vertical and temporal resolutions of the images help us to record important changes in the earth's atmosphere and indulge in the prediction of related changes. The satellite images are relayed from two different types of satellites. One is the geostationary and other is the polar orbiting satellite.
The geostationary satellites are positioned at a height above the equator. These satellites remain suspended over the same spot. The geostationary satellite provides pictures every 15 minutes or less. The images have practically the same resolution as the ones provided by lower polar-orbiting satellites. The powerful computer networking system within processes data for even the relatively smallest land and water areas.
Polar-orbiting satellites pass over the Earth from the North pole to the South pole. A time span of 1 hour and 42 minutes is taken to complete each orbit and during this time, the Earth turns by about 25 degrees. This empowers the inset computing system to deliver satellite images of different parts of the surface with every orbit. The polar orbiting satellite orbits much lower than the geostationary satellite.
Hence, the images provided are more detailed. This helps in understanding cloud structure. The computing instruments and equipment within, also measure temperature vertically through the atmosphere. The resultant numerical forecasting models help with analysis of the state of the atmosphere. Images are stored in digital form and relayed via electromagnetic transmissions to base stations for analysis.
Satellite Imaging Equipment
NASA Satellite photos are the result of application of a variety of instruments. Each instrument or radiometer has its own unique performance. While some measure temperature and humidity vertically, like the spectrometers and interferometers; others act as remote sensing instruments that emit radiation from a transmitting device, like the radar.
The measurements made by these in-built systems help weather bureaus on the planet to analyze and assess rainfall, surface wind speed and other atmosphere related parameters. The information transmitted by the NASA satellites is numerical in nature and the images need further analyzing for accurate forecasting.
Types of NASA Satellite Pictures
NASA satellite pictures are of two basic types - visible satellite images and infrared or oer electromagnetic wavelength images.
Visible satellite images are black and white or colored images provided by some of the most powerful cameras installed on satellites. While clouds usually appear white, land and water surfaces appear black. These images enable access to reflected solar energy or radiation, since visible imagery is produced on account of reflected sunlight and is available only during the day. Visible imagery has a higher resolution that offers details on smaller features.
The infrared channel is activated in the presence of heat. The images are the result of the deflection of heat emitted by the earth's surface, clouds, and the atmosphere and the re-emitting of the same. The infrared channel works on the principles of re-emitted radiation.
NASA satellite pictures are available 24 hours a day. The colorized imagery highlight land and water features and display temperature data to estimate cloud heights. The images act as observational platforms to enhance human life on the planet.