Satellite imagery
Satellite images (also Earth observation imagery, spaceborne photography, or simply satellite photo) are
History
The first images from space were taken on
All satellite images produced by NASA are published by NASA Earth Observatory and are freely available to the public. Several other countries have satellite imaging programs, and a collaborative European effort launched the ERS and Envisat satellites carrying various sensors. There are also private companies that provide commercial satellite imagery. In the early 21st century satellite imagery became widely available when affordable, easy to use software with access to satellite imagery databases was offered by several companies and organizations.
Uses
Satellite images have many applications in
Data characteristics
This section splitting the content into a new article. (February 2019) |
There are five types of resolution when discussing satellite imagery in remote sensing: spatial, spectral, temporal, radiometric and geometric. Campbell (2002)[6] defines these as follows:
- spatial resolution is defined as the pixel size of an image representing the size of the surface area (i.e. m2) being measured on the ground, determined by the sensors' instantaneous field of view (IFOV);
- spectral resolution is defined by the wavelength interval size (discrete segment of the Electromagnetic Spectrum) and number of intervals that the sensor is measuring;
- temporal resolution is defined by the amount of time (e.g. days) that passes between imagery collection periods for a given surface location
- Radiometric resolution is defined as the ability of an imaging system to record many levels of brightness (contrast for example) and to the effective bit-depth of the sensor (number of grayscale levels) and is typically expressed as 8-bit (0–255), 11-bit (0–2047), 12-bit (0–4095) or 16-bit (0–65,535).
- Geometric resolution refers to the satellite sensor's ability to effectively image a portion of the Earth's surface in a single pixel and is typically expressed in terms of Corona.[citation needed]
The
Satellite imagery is sometimes supplemented with aerial photography, which has higher resolution, but is more expensive per square meter. Satellite imagery can be combined with vector or raster data in a GIS provided that the imagery has been spatially rectified so that it will properly align with other data sets.
Imaging satellites
Public domain
Satellite imaging of the Earth surface is of sufficient public utility that many countries maintain satellite imaging programs. The United States has led the way in making these data freely available for scientific use. Some of the more popular programs are listed below, recently followed by the European Union's Sentinel constellation.
CORONA
The
Landsat
Landsat is the oldest continuous Earth-observing satellite imaging program. Optical Landsat imagery has been collected at 30 m resolution since the early 1980s. Beginning with Landsat 5, thermal infrared imagery was also collected (at coarser spatial resolution than the optical data). The Landsat 7, Landsat 8, and Landsat 9 satellites are currently in orbit.
MODIS
MODIS has collected near-daily satellite imagery of the earth in 36 spectral bands since 2000. MODIS is on board the NASA Terra and Aqua satellites.
Sentinel
The ESA is currently developing the
ASTER
The ASTER is an imaging instrument onboard Terra, the flagship satellite of NASA's Earth Observing System (EOS) launched in December 1999. ASTER is a cooperative effort between NASA, Japan's Ministry of Economy, Trade and Industry (METI), and Japan Space Systems (J-spacesystems). ASTER data is used to create detailed maps of land surface temperature, reflectance, and elevation. The coordinated system of EOS satellites, including Terra, is a major component of NASA's Science Mission Directorate and the Earth Science Division. The goal of NASA Earth Science is to develop a scientific understanding of the Earth as an integrated system, its response to change, and to better predict variability and trends in climate, weather, and natural hazards.[8]
- Land surface climatology—investigation of land surface parameters, surface temperature, etc., to understand land-surface interaction and energy and moisture fluxes
- Vegetation and ecosystem dynamics—investigations of vegetation and soil distribution and their changes to estimate biological productivity, understand land-atmosphere interactions, and detect ecosystem change
- Volcano monitoring—monitoring of eruptions and precursor events, such as gas emissions, eruption plumes, development of lava lakes, eruptive history and eruptive potential
- Hazard monitoring—observation of the extent and effects of wildfires, flooding, coastal erosion, earthquake damage, and tsunami damage
- Hydrology—understanding global energy and hydrologic processes and their relationship to global change; included is evapotranspiration from plants
- Geology and soils—the detailed composition and geomorphologic mapping of surface soils and bedrocks to study land surface processes and Earth's history
- Land surface and land cover change—monitoring desertification, deforestation, and urbanization; providing data for conservation managers to monitor protected areas, national parks, and wilderness areas
Meteosat
The
- The Meteosat visible and infrared imager (MVIRI), three-channel imager: visible, infrared and water vapour; It operates on the first generation Meteosat, Meteosat-7 being still active.
- The 12-channel Spinning Enhanced Visible and Infrared Imager (SEVIRI) includes similar channels to those used by MVIRI, providing continuity in climate data over three decades; Meteosat Second Generation(MSG).
- The Flexible Combined Imager (FCI) on Meteosat Third Generation (MTG) will also include similar channels, meaning that all three generations will have provided over 60 years of climate data.
Private domain
Several satellites are built and maintained by private companies, as follows.
GeoEye
GeoEye's
Maxar
Maxar's
Maxar's WorldView-3 satellite provides high resolution commercial satellite imagery with 0.31 m spatial resolution. WVIII also carries a short wave infrared sensor and an atmospheric sensor[11]
Airbus Intelligence
Spot Image
The 3
Planet's RapidEye
In 2015, Planet acquired
ImageSat International
Earth Resource Observation Satellites, better known as "EROS" satellites, are lightweight, low earth orbiting, high-resolution satellites designed for fast maneuvering between imaging targets. In the commercial high-resolution satellite market, EROS is the smallest very high resolution satellite; it is very agile and thus enables very high performances. The satellites are deployed in a circular Sun-synchronous near polar orbit at an altitude of 510 km (± 40 km). EROS satellites imagery applications are primarily for intelligence, homeland security and national development purposes but also employed in a wide range of civilian applications, including: mapping, border control, infrastructure planning, agricultural monitoring, environmental monitoring, disaster response, training and simulations, etc.
EROS A – a high resolution satellite with 1.9–1.2m resolution panchromatic was launched on December 5, 2000.
EROS B – the second generation of Very High Resolution satellites with 70 cm resolution panchromatic, was launched on April 25, 2006.
EROS C2 - the third generation of Very High Resolution satellites with 30cm. resolution panchromatic, was launched in 2021.
EROS C3 - the third generation of Very High Resolution satellites with 30cm. resolution panchromatic and multispectral, was launched in 2023.
China Siwei
GaoJing-1 / SuperView-1 (01, 02, 03, 04) is a commercial constellation of Chinese remote sensing satellites controlled by China Siwei Surveying and Mapping Technology Co. Ltd. The four satellites operate from an altitude of 530 km and are phased 90° from each other on the same orbit, providing 0.5m panchromatic resolution and 2m multispectral resolution on a swath of 12 km.[14][15]
Disadvantages
Because the total area of the land on Earth is so large and because resolution is relatively high, satellite databases are huge and
Commercial satellite companies do not place their imagery into the public domain and do not sell their imagery; instead, one must acquire a license to use their imagery. Thus, the ability to legally make derivative works from commercial satellite imagery is diminished.
Privacy concerns have been brought up by some who wish not to have their property shown from above. Google Maps responds to such concerns in their FAQ with the following statement: "We understand your privacy concerns... The images that Google Maps displays are no different from what can be seen by anyone who flies over or drives by a specific geographic location."[16]
See also
- Aerial photography
- Earth observation satellite
- Moderate-resolution imaging spectroradiometer
- Reconnaissance satellite
- Remote sensing
- Shuttle Radar Topography Mission
- Stratellite
- Timeline of first images of Earth from space
- Virtual globe
- NASA World Wind
- Weather satellite
References
- ^ The First Photo From Space Archived 2014-01-06 at the Wayback Machine, Tony Reichhardt, Air & Space Magazine, November 01, 2006
- ^ "50 years of Earth Observation". 2007: A Space Jubilee. European Space Agency. October 3, 2007. Archived from the original on 2012-01-30. Retrieved 2008-03-20.
- ^ "First Picture from Explorer VI Satellite". NASA. Archived from the original on 2009-11-30.
- ^ "When was the Landsat 9 satellite launched?". www.usgs.gov. Archived from the original on 2021-10-25. Retrieved 2021-10-25.
- ^ Radford, Benjamin (2019). "Anomaly Hunting with Satellite Images". Skeptical Inquirer. Vol. 43, no. 4. Center for Inquiry. pp. 32–33.
- ^ Campbell, J. B. 2002. Introduction to Remote Sensing. New York London: The Guilford Press[pages needed]
- ^ Daniel A. Begun (23 February 2009). "World's Highest-Resolution Satellite Imagery". HotHardware. Archived from the original on 2009-02-26. Retrieved 2013-06-09.
- ^ "ASTER Mission". ASTER. Jet Propulsion Laboratory. Archived from the original on 2005-03-22. Retrieved 2015-04-06.
- ^ Shalal-Esa, Andrea (September 6, 2008). "GeoEye launches high-resolution satellite". Reuters. Archived from the original on 2009-02-22. Retrieved 2008-11-07.
- ^ "Ball Aerospace & Technologies Corp". Archived from the original on 2016-03-13. Retrieved 2008-11-07.
- ^ "High Resolution Aerial Satellite Images & Photos". Archived from the original on 2014-05-20. Retrieved 2014-10-24.
- ^ "Pléiades Neo". Archived from the original on 2023-01-28. Retrieved 2021-06-24.
- Space News. Retrieved March 3, 2023.
- ^ "GaoJing / SuperView - Satellite Missions". eoPortal Directory. Archived from the original on 2019-12-03. Retrieved 2019-11-14.
- ^ "GaoJing-1 01, 02, 03, 04 (SuperView 1)". Gunter's Space Page. Archived from the original on 2019-07-16. Retrieved 2019-11-14.
- ^ Catherine Betts told the Associated Press (2007) [1]
External links
- ESA Envisat Meris – 300m – the most detailed image of the entire Earth to date, made by the European Space Agency's Envisat Meris.
- Blue Marble: Next Generation – a detailed true-color image of the entire Earth.
- World Wind – an open source 3D Earth-viewing software developed by NASA that accesses NASA JPL database