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{{Short description|
[[File:First photo from space.jpg|thumb|The first images from space were taken on the sub-orbital [[V-2 rocket]] flight launched by the U.S. on October 24, 1946.]]
[[File:Fortaleza, centro da cidade e aeroporto.JPG|thumb|Satellite image of [[Fortaleza]].]]
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== History ==
{{Further|First images of Earth from space}}
[[Image:First satellite photo - Explorer VI.jpg|thumb|upright|
The first images from space were taken on [[Sub-orbital spaceflight|sub-orbital flights]]. The U.S-launched [[V-2]] flight on October 24, 1946, took one image every 1.5 seconds. With an [[Apsis|apogee]] of 65 miles (105 km), these photos were from five times higher than the previous record, the 13.7 miles (22 km) by the Explorer II balloon mission in 1935.<ref>[http://www.airspacemag.com/space-exploration/FEATURE-FirstPhoto.html The First Photo From Space] {{Webarchive|url=https://web.archive.org/web/20140106230732/http://www.airspacemag.com/space-exploration/FEATURE-FirstPhoto.html |date=2014-01-06 }}, Tony Reichhardt, ''Air & Space Magazine'', November 01, 2006</ref> The first satellite (orbital) photographs of Earth were made on August 14, 1959, by the U.S. [[Explorer 6]].<ref>{{cite web | url=http://www.esa.int/esaMI/Space_Year_2007/SEMP4FEVL2F_0.html | title=50 years of Earth Observation | work=2007: A Space Jubilee | publisher=[[European Space Agency]] | date=October 3, 2007 | access-date=2008-03-20 | archive-date=2012-01-30 | archive-url=https://web.archive.org/web/20120130034957/http://www.esa.int/esaMI/Space_Year_2007/SEMP4FEVL2F_0.html | url-status=live }}</ref><ref>{{cite web |url=http://grin.hq.nasa.gov/ABSTRACTS/GPN-2002-000200.html |title=First Picture from Explorer VI Satellite |publisher=NASA |url-status=dead |archive-url=https://web.archive.org/web/20091130171224/http://grin.hq.nasa.gov/ABSTRACTS/GPN-2002-000200.html |archive-date=2009-11-30 }}</ref> The first satellite photographs of the [[Moon]] might have been made on October 6, 1959, by the Soviet satellite [[Luna 3]], on a mission to photograph the far side of the Moon. [[The Blue Marble]] photograph was taken from space in 1972, and has become very popular in the media and among the public. Also in 1972 the United States started the [[Landsat program]], the largest program for acquisition of imagery of Earth from space. In 1977, the first real time satellite imagery was acquired by the United States's [[KH-11]] satellite system. The most recent Landsat satellite, [[Landsat 9]], was launched on 27 September 2021.<ref>{{Cite web|title=When was the Landsat 9 satellite launched?|url=https://www.usgs.gov/faqs/when-was-landsat-9-satellite-launched?qt-news_science_products=0#qt-news_science_products|access-date=2021-10-25|website=www.usgs.gov|language=en|archive-date=2021-10-25|archive-url=https://web.archive.org/web/20211025220057/https://www.usgs.gov/faqs/when-was-landsat-9-satellite-launched?qt-news_science_products=0#qt-news_science_products|url-status=live}}</ref>
[[Image:TIROS-1-Earth.png|thumb|left|The first television image of Earth from space transmitted by the [[TIROS-1]] weather satellite in 1960.]]
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 [[European Remote-Sensing Satellite|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.
== Satellite image applications ==
Satellite images have many applications in various fields.
* [[Weather]]: They guide meteorologists in forecasting patterns, tracking storms, and understanding climate change.
* [[Oceanography]]: By measuring sea temperatures and monitoring ecosystems, satellite images unlock insights into our oceans' health and global climate.
* [[Agriculture]] and [[Fishing]]: Satellite data helps locate fish populations, assess crop health, and optimize resource use for a thriving agricultural and fishing industry.
* [[Biodiversity]]: Conservation efforts leverage satellite technology to map habitats, monitor ecosystem changes, and protect endangered species.
* [[forestry]]: Satellite data empowers sustainable forestry by tracking deforestation, assessing fire risks, and managing resources effectively.
* [[landscape]]: Analyzing land use patterns with satellite images supports urban planning and facilitates sustainable development initiatives.
Less mainstream uses include anomaly hunting, a criticized investigation technique involving the search of satellite images for unexplained phenomena.<ref>{{cite magazine |last=Radford |first=Benjamin |author-link=Benjamin Radford |date=2019 |title=Anomaly Hunting with Satellite Images |magazine=[[Skeptical Inquirer]] |publisher=[[Center for Inquiry]] |volume=43 |issue=4 |pages=32–33 }}</ref>
The spectrum of satellite images is diverse, such as visible light, near-infrared light, infrared light spectrum and radar, etc. These spectra can provide scientists with a lot of rich information. In addition to the satellite applications mentioned above, these data can serve as powerful educational tools, advance scientific research and promote a deeper understanding of our environment. This shows that satellite imagery provides rich information and can promote global development.
== Data characteristics ==
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* 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 [[Ground sample distance]], or GSD. GSD is a term containing the overall optical and systemic noise sources and is useful for comparing how well one sensor can "see" an object on the ground within a single pixel. For example, the GSD of Landsat is ≈30m, which means the smallest unit that maps to a single pixel within an image is ≈30m x 30m. The latest commercial satellite (GeoEye 1) has a GSD of 0.41 m. This compares to a 0.3 m resolution obtained by some early military film based [[Reconnaissance satellite]] such as [[Corona (satellite)|Corona]].{{Citation needed|reason=Campbell, J. B. 2002, above, is said to define only spatial, spectral, temporal and radiometric resolutions.|date=September 2016}}
The [[image resolution|resolution]] of satellite images varies depending on the instrument used and the altitude of the satellite's orbit. For example, the [[Landsat]] archive offers repeated imagery at 30 meter resolution for the planet, but most of it has not been processed from the raw data. [[Landsat 7]] has an average return period of 16 days. For many smaller areas, images with resolution as
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 [[Geographic information system|GIS]] provided that the imagery has been spatially rectified so that it will properly align with other data sets.
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{{further|Earth observing satellites}}
=== Public
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 ''[[Corona (satellite)|CORONA]]'' program was a series of [[United States|American]] strategic [[
==== Landsat ====
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====ASTER====
The ''[[Advanced Spaceborne Thermal Emission and Reflection Radiometer|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.<ref name="Jet Propulsion Laboratory">{{cite web |url=http://asterweb.jpl.nasa.gov/mission.asp |archive-url=https://web.archive.org/web/20050322161843/http://asterweb.jpl.nasa.gov/mission.asp |url-status=dead |archive-date=2005-03-22 |title=ASTER
* Land surface climatology—investigation of land surface parameters, [[Satellite temperature measurements|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
* 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 ====
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*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")|Meteosat Third Generation]] (MTG) will also include similar channels, meaning that all three generations will have provided over 60 years of climate data.
==== Himawari ====
The [[Himawari (satellites)|Himawari]] satellite series represents a significant leap forward in meteorological observation and environmental monitoring. With their advanced imaging technology and frequent data updates, Himawari-8 and Himawari-9 have become indispensable tools for weather forecasting, disaster management, and climate research, benefiting not only Japan but the entire Asia-Pacific region.
*Frequent Updates:These satellites can provide full-disk images of the Asia-Pacific region every 10 minutes, and even more frequently( every 2.5 minutes) for specific areas (Japan), ensuring that meteorologists have up-to-dte information for accurate weather forecasting.
*[[Spectral band|Spectral Bands]]:
**Visible Light Bands (0.47 μm, 0.51 μm, 0.64 μm): These bands are used for daytime cloud, land, and ocean surface observations. They provide high-resolution images that are critical for tracking cloud movements and assessing weather conditions.
**Near-Infrared Bands (0.86 μm, 1.6 μm, 2.3 μm, 6.9 μm, 7.3 μm, 8.6 μm, 9.6 μm, 11.2 μm, 13.3 μm): These bands help in distinguishing between different types of clouds, vegetation, and surface features. They are particularly useful for detecting fog, ice, and snow.
**Infrared Bands (3.9 μm, 6.2 μm, 10.4 μm, 12.4 μm): The remaining bands cover the thermal infrared spectrum. These bands are crucial for measuring cloud-top temperatures, sea surface temperatures, and atmospheric water vapor content. They enable continuous monitoring of weather patterns.
*Advanced Imaging Technology: Himawari-8 and Himawari-9 are equipped with the [https://www.data.jma.go.jp/mscweb/en/himawari89/space_segment/spsg_ahi.html Advanced Himawari Imager (AHI)], which provides high-resolution images of the Earth. The AHI can capture images in 16 different spectral bands, allowing for detailed observation of weather patterns, clouds, and environmental phenomena.
=== Private domain ===
Several satellites are built and maintained by private companies, as follows.
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====GeoEye====
GeoEye's [[GeoEye-1]] satellite was launched on September 6, 2008.<ref>{{cite news |url=https://www.reuters.com/article/rbssTechMediaTelecomNews/idUSN0633403420080906?sp=true |last=
[[File:WV2 OPER WV-110 2A 20130710T113935 N51-307 W002-959 1001.SIP.ZIP BID.png|alt=WorldView-2 image of
====Maxar====
Maxar's [[WorldView-2]] satellite provides high resolution commercial satellite imagery with 0.46 m spatial resolution (panchromatic only).<ref name="urlBall Aerospace & Technologies Corp.">{{cite web |url=http://www.ballaerospace.com/page.jsp?page=81 |title=Ball Aerospace & Technologies Corp. |access-date=2008-11-07 |archive-date=2016-03-13 |archive-url=https://web.archive.org/web/20160313074829/http://www.ballaerospace.com/page.jsp?page=81 |url-status=live }}</ref> The 0.46 meters resolution of WorldView-2's [[panchromatic]] images allows the satellite to distinguish between objects on the ground that are at least 46 cm apart. Similarly Maxar's [[QuickBird]] satellite provides 0.6 meter resolution (at [[nadir]]) panchromatic images.
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<ref name="urlMaxar WorldView3">{{cite web
====Airbus Intelligence====
[[File:PHR1A MS 202004061549461.jpg|alt=Pleiades image of the central park-New York city.|thumb|upright|Pleiades image of the central park-New York city.]]
[[Pléiades (satellite)|''Pléiades'']] [[Satellite constellation|constellation]] is composed of two very-high-resolution (50 centimeters pan & 2.1 meter spectral) optical [[Earth-imaging satellite
{{ill|Pléiades Neo|fr}}<ref>
====Spot Image====
[[File:Bratislava SPOT 1027.jpg|thumb|right|SPOT image of [[Bratislava]]]]
[[File:ISS061-E-138240 - View of the Philippines.jpg|thumb|right|Satellite view of Southern [[Luzon]] taken by the [[ISS]]]]
The 3 [[SPOT (satellite)|SPOT satellites]] in orbit (Spot 5, 6, 7) provide very high resolution images – 1.5 m for Panchromatic channel, 6m for Multi-spectral (R,G,B,NIR). Spot Image also distributes multiresolution data from other optical satellites, in particular from Formosat-2 (Taiwan) and Kompsat-2 (South Korea) and from radar satellites (TerraSar-X, ERS, Envisat, Radarsat). [[Spot Image]] is also the exclusive distributor of data from the high resolution [[Pleiades satellites]] with a resolution of 0.50 meter or about 20 inches. The launches occurred in 2011 and 2012, respectively. The company also offers infrastructures for receiving and processing, as well as added value options.
====Planet's RapidEye====
In 2015, Planet acquired [[BlackBridge]], and its constellation of five [[RapidEye]] satellites, launched in August 2008.<ref>{{cite
====ImageSat International====
[[EROS (satellite)|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
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.
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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.<ref>{{Cite web|url=https://directory.eoportal.org/web/eoportal/satellite-missions/content/-/article/gaojing|title=GaoJing / SuperView - Satellite Missions
==Disadvantages==
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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: "
== See also ==
* [[Aerial photography]]
* [[Earth observation satellite]]
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** [[NASA World Wind]]
* [[Weather satellite]]
==References==
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