Have you ever looked up at the sky and wondered what’s up there? In today’s world, the answer is more than just stars and planets. Satellites, both commercial and government-owned, are circling the Earth and capturing images of everything from natural disasters to your backyard.
Satellites are essential to our modern world, providing us with everything from GPS navigation to satellite TV. But they can also collect information about the Earth’s surface and atmosphere. This process is known as remote sensing and has many applications in fields like urban planning, agriculture, and environmental monitoring.
In this blog post, we’ll explore the world of satellite imagery and remote sensing, discussing the different types of satellites, use cases for satellite imagery, and where to find this information.
Types of Satellites
Satellites come in many shapes and sizes and orbit the Earth at various altitudes. Here are some of the most common types of satellites:
- Geostationary Earth Orbit (GEO): These satellites orbit the Earth at around 36,000 km and remain fixed in the same position relative to the Earth’s surface. GEO satellites are used for applications like weather forecasting and communication.
- Low Earth Orbit (LEO): They orbit the Earth at an altitude of between 500-1500 km. They move quickly relative to the Earth’s surface and complete one orbit in around 90 minutes. LEO satellites are used for applications like remote sensing, GPS, and satellite imaging.
- Medium Earth Orbit (MEO) or Intermediate Circular Orbit (ICO): These satellites orbit the Earth at 6000-20,000 km. MEO/ICO satellites are used for applications like GPS and communication.
- Highly Elliptical Orbit (HEO): HEO satellites have a highly elliptical orbit that takes them to great distances from the Earth, up to 100,000 km. These satellites are used for applications like communication and weather monitoring.
Types of Satellite Imagery
Satellites can collect a wide range of data about the Earth’s surface and atmosphere, depending on the sensors they carry. Here are some of the most common types of satellite imagery:
- Multispectral Imagery: Multispectral imagery collects data across various wavelengths, from visible light to infrared. This imagery can identify different vegetation types, monitor crop health, and detect changes in land use.
- Panchromatic Imagery: Panchromatic imagery collects data in a single wavelength, usually in the visible spectrum. This type of imagery has high spatial resolution and can be used for applications like urban planning and infrastructure monitoring.
- Synthetic Aperture Radar (SAR) Imagery: SAR imagery uses radar to collect data about the Earth’s surface. This type of imagery can be used to detect changes in land use, monitor infrastructure, and even detect oil spills.
Data sources
Satellites can be divided into two main categories: commercial and open-source. Commercial satellites are owned by private companies, while governments or other public entities own open-source satellites. The satellite data is sold or made available for free, respectively. Here are some examples of the primary satellites in each category:
Commercial Satellites
- WorldView-4: This satellite is owned by Maxar Technologies and can capture images with a resolution of 30 cm.
- Pleiades: Owned by Airbus Defense and Space, this satellite can capture images with a resolution of 50 cm.
- SPOT-6/7: These twin satellites are owned by Airbus Defense and Space and can capture images with a resolution of 1.5 m.
- QuickBird: Owned by DigitalGlobe, this satellite can capture images with a resolution of 60 cm.
- GeoEye-1: This satellite is owned by Maxar Technologies and can capture images with a resolution of 41 cm.
Open-Source Satellites
- Landsat 8: This satellite is operated by the United States Geological Survey (USGS) and can capture images with a resolution of 15-30 m.
- Sentinel-2: This satellite is owned by the European Space Agency (ESA) and can capture images with a resolution of 10-60 m.
- MODIS: Operated by NASA, this satellite can capture images with a resolution of 250-1000 m.
- CBERS-4: This satellite is a joint project between Brazil and China and can capture images with a resolution of 5 m.
- ASTER: Also operated by NASA, this satellite can capture images with a resolution of 15-90 m.
Domains of application and use cases for satellite imagery
| Imagery | Resolution | Mode of Image Capturing | Use Cases |
|---|---|---|---|
| Panchromatic | High resolution (30 cm or less) | Captures light in a single wavelength | Urban planning, disaster response, forestry, geology |
| Multispectral | Moderate to high resolution (1-30 m) | Captures light in several wavelengths | Agriculture, forestry, land use/land cover classification, oceanography |
| Hyperspectral | High spectral resolution (100+ bands) | Captures light in hundreds of narrow and contiguous spectral bands | Mineralogy, geology, agriculture, forestry |
| Radar | Low to high resolution (10 m to tens of meters) | Captures microwaves that penetrate through clouds, vegetation, and soil | Agriculture, forestry, geology, disaster response |
| Thermal | Low to moderate resolution (50-100 m) | Captures radiation emitted by objects in the long-wave infrared region | Agriculture, water management, forestry, energy efficiency |
Owners, Vendors, and Platforms of Satellite Imagery
Owners
Government agencies, private companies, or international organizations typically own satellites. Here are some examples of significant satellite owners:
- National Aeronautics and Space Administration (NASA): The US government agency responsible for the civilian space program and aerospace research. NASA owns several Earth observation satellites, including the Landsat series and Terra.
- European Space Agency (ESA): An intergovernmental organization dedicated to exploring space. The ESA operates several Earth observation satellites, including the Sentinel series.
- National Oceanic and Atmospheric Administration (NOAA): A US government agency that focuses on the conditions of the oceans, major waterways, and the atmosphere. NOAA operates several weather and environmental satellites, including the Geostationary Operational Environmental Satellite (GOES) and the Polar Operational Environmental Satellite (POES).
- China National Space Administration (CNSA): The national space agency of China. CNSA operates several Earth observation satellites, including the Gaofen and Ziyuan series.
Vendors (Service Providers):
Satellite imagery is typically sold by vendors or service providers, who process and distribute the data collected by the satellites. Here are some examples of significant vendors of satellite imagery:
- DigitalGlobe: A US-based commercial vendor of high-resolution satellite imagery. DigitalGlobe operates several satellites, including WorldView-4 and GeoEye-1.
- Airbus Defence and Space: A European multinational aerospace corporation that offers Earth observation services, including satellite imagery. Airbus operates several Earth observation satellites, including the Pleiades series.
- Maxar Technologies: A US-based space technology company that provides Earth intelligence and space infrastructure. Maxar operates several satellites, including the WorldView series and the QuickBird satellite.
Platforms
- Google Earth
Google Earth is a popular platform that allows users to explore satellite imagery of the Earth’s surface, as well as 3D models of buildings, terrain, and other features. It also includes tools for measuring distances and areas, adding placemarks and annotations, and more. - Copernicus Open Access Hub
The Copernicus Open Access Hub is a data portal maintained by the European Space Agency (ESA) that provides free access to data from the Copernicus program’s Sentinel satellites. Users can search for and download a wide range of data products, including imagery, land cover maps, and more. - Sentinel Playground
Sentinel Playground is an online platform developed by Sinergise that allows users to visualize and explore satellite imagery from the Copernicus Sentinel missions. It offers a user-friendly interface with tools for browsing, searching, and viewing imagery. - USGS Earth Explorer
The USGS Earth Explorer is a data portal maintained by the US Geological Survey (USGS) that provides free access to a wide range of satellite and aerial imagery and other geospatial data. Users can search for and download data from various sources, including Landsat, Sentinel, and more. - EOSDIS Worldview
EOSDIS Worldview is a web-based platform developed by NASA that allows users to visualize and analyze satellite imagery from various sources, including MODIS, VIIRS, and more. It offers a user-friendly interface with tools for exploring and analyzing imagery. - EO Browser
EO Browser is an online platform developed by Sinergise that allows users to visualize and explore satellite imagery from various sources, including Sentinel, Landsat, and more. It offers a range of tools for imagining and analyzing imagery and creating custom image composites. - Earth Data
Earth Data is a data portal maintained by NASA that provides access to a wide range of satellite and aerial imagery and other geospatial data. Users can search for and download data from various sources, including Landsat, MODIS, and more. It also offers a range of tools and resources for working with geospatial data.
So yes, we are being watched and those are only the services and products related to planning and geography. Non-civil applications are plentiful, less well documented, and not accessible.
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