These days, you don't have to be in military intelligence to see images from Earth's orbit. People all over the world can obtain free satellite imagery from multiple satellites and space programs. With internet access and the proper tools, users can extract valuable information from images.
What is satellite imagery?
Space devices scan our planet every day with their own unique purpose. But what does this actually mean? Satellites are equipped with various sensors through which scanning or remote sensing occurs.
The sensors collect electromagnetic radiation reflected from the surface. Passive sensors collect radiation emitted by the Sun and reflected by the Earth, while active sensors emit radiation themselves and analyze it after reflection from the surface of our planet.
The human eye can only see a small portion of visible light. As for satellite sensors, they detect infrared light, ultraviolet light, or even microwaves. In satellite images, types of light invisible to humans are assigned a visible color.
Free satellite images identify surfaces and objects based on how they reflect radiation. Smooth surfaces reflect energy in one direction, while rough surfaces reflect in all directions. It helps to measure forest density and health. Infrared light can determine plant health, as healthy leaves reflect a specific frequency well.
How It Started
The first satellite photo of Earth was taken in 1959 by US Explorer 6. The picture showed the north-central Pacific Ocean and was captured over Mexico. The image was transmitted to a Hawaii ground station over 40 minutes.
However, until the seventies of the last century, satellites were not used to track the changes and events on the Earth's surface. They were mainly used for military missions. In 1972, the most comprehensive Landsat program was launched to capture images of Earth from space. In 1977, the United States' KH-11 satellite system provided the first real-time images.
The 1992 Land Remote Sensing Policy Act allowed commercial companies to launch satellites and sell data. These satellites observe and measure the Earth's features, which are applied to various fields like meteorology, environment, disaster monitoring, and cartography.
Substantial improvements in Earth observation technology, including enhancements in spectral range, resolution, and image capture frequency, also occurred during this period. Today, users can find satellite images for free and apply them for different purposes, including mapping, disaster response, and farmland monitoring.
The Era of Open Access and Public Platforms
In the 21st century, we entered a new age where satellite imagery became widely available to everyone. A variety of programs provided free access to satellite data for the public. Google Earth, launched in 2005, revolutionized public access to satellite images, allowing anyone with an internet connection to explore daily satellite imagery for free.
EOSDA LandViewer
EOS Data Analytics is a global provider of reliable and accurate satellite data analytics. The company created a range of projects to help businesses on their path to reduce negative environmental impact and resource optimization.
EOSDA LandViewer is a solution for searching and on-the-fly processing of satellite images. This GIS assistant includes a variety of handy features that can help to solve business tasks effectively.
Medium-resolution images can be obtained from the service for free. Users can also purchase high-resolution images. More than ten spectral indices are available to users to extract valuable information from space data. Users can also create their own indices by combining different spectral bands.
USGS Earth Explorer
This platform operates worldwide and provides many capabilities for acquiring and using satellite imagery. Various image sources are available to users, including Landsat and hyperspectral images from NASA's Hyperion satellite.
Copernicus Data Space Ecosystem
It is a new European Space Agency portal to facilitate access to Copernicus satellite data. The platform now seamlessly combines satellite imagery exploration and functions for processing data in a user-friendly Copernicus browser.
Google Earth
It's hard to find a more popular source of free images than Google Earth. The platform accepts most image files, including vector files, and offers various processing functions. Users can import data, apply templates, add markers, highlight key features, and draw on maps. You can also try 3D or Street View for a different perspective.
Earthdata Search by NASA
This tool enables viewing full-resolution images and interacting with them via a computer or tablet. It gives access to rainfall measurements made by global missions. NASA EarthData can also be used to fight forest fires or monitor air quality.
Applications for SAR Satellite Data
The well-being of humans depends on Earth's resources. Governments and corporations need reliable data to manage land resources and respond to changes quickly. Half of the Earth's surface is usually covered with clouds, making it difficult for optical remote sensors to image the land below, but not for synthetic-aperture radar.
SAR satellite data is precious for governmental, non-governmental, and business-specific needs. Its capabilities find use in various applications, such as
- facility monitoring for intelligence
- verifying insurance claims
- detecting maritime illegal activities
- mapping disaster damage.
Impact on Research, Education, and Public Awareness
Satellite technology has revolutionized research and education. It also contributed to public awareness. Scientists and researchers use these images to detect changes and study different events on our planet. At the same time, the public's access to free high-resolution satellite imagery has increased awareness about environmental issues.
Obstacles and Prospects in the Realm of Satellite Technology
Despite numerous achievements in the industry, some issues remain. There are still some obstacles to overcome, such as maintaining data confidentiality, interpreting complex images, and preventing misuse.
The further transformation that the development of AI and machine learning will bring in the future will help provide more profound and more complex analysis and increase the capabilities of real-time monitoring.
The availability of satellite imagery to the public was a significant development that changed how humanity interacts with the planet. The further remote sensing technology develops, the more possibilities for its application open up for people. Information received from orbit becomes integral to various aspects of our lives.
Satellite imagery not only expands human capabilities but also changes the way we interact with the planet. Data received from orbit become an integral part of life and help to learn more about the events taking place on Earth and how anthropogenic activities affect it.
