The Landsat program is the longest-running enterprise for acquisition of satellite imagery of Earth. It is a joint NASA / USGS program. On 23 July 1972, the Earth Resources Technology Satellite was launched. This was eventually renamed to Landsat 1 in 1975. [1] The most recent, Landsat 9, was launched on 27 September 2021.
The instruments on the Landsat satellites have acquired millions of images. The images, archived in the United States and at Landsat receiving stations around the world, are a unique resource for global change research and applications in agriculture, cartography, geology, forestry, regional planning, surveillance and education, and can be viewed through the U.S. Geological Survey (USGS) "EarthExplorer" website. Landsat 7 data has eight spectral bands with spatial resolutions ranging from 15 to 60 m (49 to 197 ft); the temporal resolution is 16 days. [2] Landsat images are usually divided into scenes for easy downloading. Each Landsat scene is about 115 miles long and 115 miles wide (or 100 nautical miles long and 100 nautical miles wide, or 185 kilometers long and 185 kilometers wide).
In 1965, William T. Pecora, the then director of the United States Geological Survey, proposed the idea of a remote sensing satellite program to gather facts about the natural resources of our planet. Pecora stated that the program was "conceived in 1966 largely as a direct result of the demonstrated utility of the Mercury and Gemini orbital photography to Earth resource studies." While weather satellites had been monitoring Earth's atmosphere since 1960 and were largely considered useful, there was no appreciation of terrain data from space until the mid-1960s. So, when Landsat 1 was proposed, it met with intense opposition from the Bureau of Budget and those who argued high-altitude aircraft would be the fiscally responsible choice for Earth remote sensing. Concurrently, the Department of Defense feared that a civilian program such as Landsat would compromise the secrecy of their reconnaissance missions. Additionally, there were geopolitical concerns about photographing foreign countries without permission. In 1965, NASA began methodical investigations of Earth remote sensing using instruments mounted on planes. In 1966, the USGS convinced the Secretary of the Interior, Stewart Udall, to announce that the Department of the Interior (DOI) was going to proceed with its own Earth-observing satellite program. This savvy political stunt coerced NASA to expedite the building of Landsat. But budgetary constraints and sensor disagreements between application agencies (notably the Department of Agriculture and DOI) again stymied the satellite construction process. Finally, by 1970 NASA had a green light to build a satellite. Remarkably, within only two years, Landsat 1 was launched, heralding a new age of remote sensing of land from space. [3]
The Hughes Aircraft Company from Santa Barbara Research Center initiated, designed, and fabricated the first three Multispectral Scanners (MSS) in 1969. The first MSS prototype, designed by Virginia Norwood, was completed within nine months, in the fall of 1970. It was tested by scanning Half Dome at Yosemite National Park. For this design work Norwood was called "The Mother of Landsat". [4]
Working at NASA's Goddard Space Flight Center, Valerie L. Thomas managed the development of early Landsat image processing software systems and became the resident expert on the Computer Compatible Tapes, or CCTs, that were used to store early Landsat imagery. Thomas was one of the image processing specialists who facilitated the ambitious Large Area Crop Inventory Experiment, known as LACIE — a project that showed for the first time that global crop monitoring could be done with Landsat satellite imagery. [5]
The program was initially called the Earth Resources Technology Satellites Program, which was used from 1966 to 1975. In 1975, the name was changed to Landsat. In 1979, President of the United States Jimmy Carter's Presidential Directive 54 [6] [7] transferred Landsat operations from NASA to National Oceanic and Atmospheric Administration (NOAA), recommended development of a long term operational system with four additional satellites beyond Landsat 3, and recommended transition to private sector operation of Landsat. This occurred in 1985 when the Earth Observation Satellite Company (EOSAT), a partnership of Hughes Aircraft Company and RCA, was selected by NOAA to operate the Landsat system with a ten-year contract. EOSAT operated Landsat 4 and Landsat 5, had exclusive rights to market Landsat data, and was to build Landsats 6 and 7.
In 1989, this transition had not been fully completed when NOAA's funding for the Landsat program was due to run out (NOAA had not requested any funding, and U.S. Congress had appropriated only six months of funding for the fiscal year) [8] and NOAA directed that Landsat 4 and Landsat 5 be shut down. [9]
The head of the newly formed National Space Council, Vice President Dan Quayle, noted the situation and arranged emergency funding that allowed the program to continue with the data archives intact. [8] [9] [10] [11]
Again in 1990 and 1991, Congress provided only half of the year's funding to NOAA, requesting that agencies that used Landsat data provide the funding for the other six months of the upcoming year. [8]
In 1992, various efforts were made to procure funding for follow on Landsats and continued operations, but by the end of the year EOSAT ceased processing Landsat data. Landsat 6 was finally launched on 5 October 1993, but was lost in a launch failure. Processing of Landsat 4 and 5 data was resumed by EOSAT in 1994. NASA finally launched Landsat 7 on 15 April 1999.
The value of the Landsat program was recognized by Congress in October 1992 when it passed the Land Remote Sensing Policy Act (Public Law 102-555) authorizing the procurement of Landsat 7 and assuring the continued availability of Landsat digital data and images, at the lowest possible cost, to traditional and new users of the data.
Instrument | Picture | Launched | Terminated | Duration | Notes |
---|---|---|---|---|---|
Landsat 1 | ![]() | 23 July 1972 | 6 January 1978 | 5 years, 6 months and 14 days | Originally named Earth Resources Technology Satellite 1. Landsat 1 carried two vital instruments: a camera built by the Radio Corporation of America (RCA) known as the Return Beam Vidicon (RBV); and the Multi spectral Scanner (MSS) built by the Hughes Aircraft Company. |
Landsat 2 | ![]() | 22 January 1975 | 25 February 1982 | 7 years, 1 month and 3 days | Nearly identical copy of Landsat 1. Payload consisting of a Return Beam Vidicon (RBV) and a Multi spectral Scanner (MSS). The specifications of these instruments were identical to Landsat 1. |
Landsat 3 | ![]() | 5 March 1978 | 31 March 1983 | 5 years and 26 days | Nearly identical copy of Landsat 1 and Landsat 2. Payload consisting of a Return Beam Vidicon (RBV) as well as a Multi spectral Scanner (MSS). Included with the MSS was a short-lived thermal band. MSS data was considered more scientifically applicable than the RBV which was rarely used for engineering evaluation purposes. |
Landsat 4 | ![]() | 16 July 1982 | 14 December 1993 | 11 years, 4 months and 28 days | Landsat 4 carried an updated Multi Spectral Scanner (MSS) used on previous Landsat missions, as well as a Thematic Mapper. |
Landsat 5 | ![]() | 1 March 1984 | 5 June 2013 [12] | 29 years, 3 months and 4 days | Nearly identical copy of Landsat 4. Longest Earth-observing satellite mission in history. Designed and built at the same time as Landsat 4, this satellite carried the same payload consisting of a Multi Spectral Scanner (MSS) as well as a Thematic Mapper. |
Landsat 6 | ![]() | 5 October 1993 | 5 October 1993 | 0 days | Failed to reach orbit. Landsat 6 was an upgraded version of its predecessors. Carrying the same Multi spectral Scanner (MSS) but also carrying an Enhanced Thematic Mapper, which added a 15m resolution panchromatic band. |
Landsat 7 | ![]() | 15 April 1999 | active | 25 years, 2 months and 14 days | Operating with scan line corrector disabled since May 2003. [13] The main component on Landsat 7 was the Enhanced Thematic Mapper Plus (ETM+). Still consisting of the 15m-resolution panchromatic band, but also includes a full aperture calibration. This allows for 5% absolute radiometric calibration. [14] |
Landsat 8 | ![]() | 11 February 2013 | active | 11 years, 4 months and 18 days | Originally named Landsat Data Continuity Mission from launch until 30 May 2013, when NASA operations were turned over to United States Geological Survey (USGS). [15] Landsat 8 has two sensors with its payload, the Operational Land Imager (OLI) and the Thermal InfraRed Sensor (TIRS). [16] |
Landsat 9 | ![]() | 27 September 2021 | active | 2 years, 9 months and 2 days | Landsat 9 is a rebuild of its predecessor Landsat 8. [17] [18] |
Landsat 1 through 5 carried the Landsat Multispectral Scanner (MSS). Landsat 4 and 5 carried both the MSS and Thematic Mapper (TM) instruments. Landsat 7 uses the Enhanced Thematic Mapper Plus (ETM+) scanner. Landsat 8 uses two instruments, the Operational Land Imager (OLI) for optical bands and the Thermal Infrared Sensor (TIRS) for thermal bands. The band designations, bandpasses, and pixel sizes for the Landsat instruments are: [19]
Landsat 1–3 MSS | Landsat 4–5 MSS | Wavelength (micrometers) | Resolution (meters) |
---|---|---|---|
Band 4 – Green | Band 1 – Green | 0.5 – 0.6 | 60* |
Band 5 – Red | Band 2 – Red | 0.6 – 0.7 | 60* |
Band 6 – Near Infrared (NIR) | Band 3 – NIR | 0.7 – 0.8 | 60* |
Band 7 – NIR | Band 4 – NIR | 0.8 – 1.1 | 60* |
* Original MSS pixel size was 79 x 57 meters; production systems now resample the data to 60 meters.
Bands | Wavelength (micrometers) | Resolution (meters) |
---|---|---|
Band 1 – Blue | 0.45 – 0.52 | 30 |
Band 2 – Green | 0.52 – 0.60 | 30 |
Band 3 – Red | 0.63 – 0.69 | 30 |
Band 4 – NIR | 0.76 – 0.90 | 30 |
Band 5 – Shortwave Infrared (SWIR) 1 | 1.55 – 1.75 | 30 |
Band 6 – Thermal | 10.40 – 12.50 | 120* (30) |
Band 7 – SWIR 2 | 2.08 – 2.35 | 30 |
* TM Band 6 was acquired at 120-meter resolution, but products are resampled to 30-meter pixels.
Bands | Wavelength (micrometers) | Resolution (meters) |
---|---|---|
Band 1 – Blue | 0.45 – 0.52 | 30 |
Band 2 – Green | 0.52 – 0.60 | 30 |
Band 3 – Red | 0.63 – 0.69 | 30 |
Band 4 – NIR | 0.77 – 0.90 | 30 |
Band 5 – SWIR 1 | 1.55 – 1.75 | 30 |
Band 6 – Thermal | 10.40 – 12.50 | 60* (30) |
Band 7 – SWIR 2 | 2.09 – 2.35 | 30 |
Band 8 – Panchromatic | 0.52 – 0.90 | 15 |
* ETM+ Band 6 is acquired at 60-meter resolution, but products are resampled to 30-meter pixels.
Bands | Wavelength (micrometers) | Resolution (meters) |
---|---|---|
Band 1 - Ultra Blue (coastal/aerosol) | 0.435 – 0.451 | 30 |
Band 2 - Blue | 0.452 – 0.512 | 30 |
Band 3 - Green | 0.533 – 0.590 | 30 |
Band 4 – Red | 0.636 – 0.673 | 30 |
Band 5 – NIR | 0.851 – 0.879 | 30 |
Band 6 – SWIR 1 | 1.566 – 1.651 | 30 |
Band 7 – SWIR 2 | 2.107 – 2.294 | 30 |
Band 8 – Panchromatic | 0.503 – 0.676 | 15 |
Band 9 – Cirrus | 1.363 – 1.384 | 30 |
Band 10 – Thermal 1 | 10.60 – 11.19 | 100* (30) |
Band 11 – Thermal 2 | 11.50 – 12.51 | 100* (30) |
* TIRS bands are acquired at 100 meter resolution, but are resampled to 30 meter in delivered data product.
An advantage of Landsat imagery, and remote sensing in general, is that it provides data at a synoptic global level that is impossible to replicate with in situ measurements. However, there are tradeoffs between the local detail of the measurements (radiometric resolution, number of spectral bands) and the spatial scale of the area being measured. Landsat imagery is coarse in spatial resolution compared to using other remote sensing methods, such as imagery from airplanes. Compared to other satellites, Landsat's spatial resolution is relatively high, yet revisit time is relatively less frequent.
The Landsat program incorporated the Multispectral Scanner (MSS) from its first mission up to its fifth. The MSS, gave the United States an advantage in satellite imaging, facilitating the launch of Landsat ahead of the French SPOT satellite.
The MSS was unique in its design. Rather than a static camera, it employed a moving mirror, capturing Earth's images in four distinct spectral bands. This capability allowed the MSS to record variations in sunlight reflected from the Earth. Notably, Landsat 3's MSS was further advanced, with an added capability to detect heat radiation. [21]
One of the prominent features of the MSS was its consistent imaging. Each captured frame represented an area on the Earth's surface approximately 83 meters in length and 68 meters in width. Additionally, the system was designed to ensure a continuous image sweep across a swath equivalent to 185 km on the Earth's surface. The MSS's design also emphasized precision; by precisely timing the mirror's movements, it ensured that consecutive images did not overlap. [21]
However, by the 1980s, the cost dynamics shifted. Accessing Landsat's imagery became substantially more expensive, making the French SPOT satellite's images a more cost-effective alternative for many users. The rise in Landsat's prices can be attributed to U.S. policy shifts, initiated under President Carter's leadership and finalized during President Reagan's administration. [7] [22]
Landsat data provides information that allows scientists to predict the distribution of species, as well as detecting both naturally occurring and human-generated changes over a greater scale than traditional data from field work. The different spectral bands used on satellites in the Landsat program provide many applications, ranging from ecology to geopolitical matters. Land cover determination is a common use of Landsat imagery around the world. [23]
Landsat imagery provides one of the longest uninterrupted time series available from any single remote sensing program, spanning from 1972 to present. [24] Looking to the future, the successful launch of Landsat-9 in 2021 shows that this time series will be continued forward. [25]
In 2015, the Landsat Advisory Group of the National Geospatial Advisory Committee reported that the top 16 applications of Landsat imagery produced savings of approximately 350 million to over 436 million dollars each year for federal and state governments, NGO's, and the private sector. That estimate did not include further savings from other uses beyond the top sixteen categories. [26] The top 16 categories for Landsat imagery use, listed in order of estimated annual savings for users, are:
Further uses of Landsat imagery include, but are not limited to: fisheries, forestry, shrinking inland water bodies, fire damage, glacier retreat, urban development, and discovery of new species. A few specific examples are explained below.
In 1975, one potential application for the new satellite-generated imagery was to find high yield fishery areas. Through the Landsat Menhaden and Thread Investigation, some satellite data of the eastern portion of the Mississippi sound and another area off the coast of the Louisiana coast data was run through classification algorithms to rate the areas as high and low probability fishing zones, these algorithms yielded a classification that was proven with in situ measurements – to be over 80% accurate and found that water color, as seen from space, and turbidity significantly correlate with the distribution of menhaden – while surface temperature and salinity do not appear to be significant factors. Water color – measured with the multispectral scanners four spectral bands, was used to infer Chlorophyll, turbidity, and possibly fish distribution. [27]
An ecological study used 16 ortho-rectified Landsat images to generate a land cover map of Mozambique's mangrove forest. The main objective was to measure the mangrove cover and above ground biomass on this zone that until now could only be estimated, the cover was found with 93% accuracy to be 2909 square kilometers (27% lower than previous estimates). Additionally, the study helped confirm that geological setting has a greater influence on biomass distribution than latitude alone - the mangrove area is spread across 16° of latitude but it the biomass volume of it was affected more strongly by geographic conditions. [28]
The shrinking of the Aral Sea has been described as "One of the planet's worst environmental disasters". Landsat imagery has been used as a record to quantify the amount of water loss and the changes to the shoreline. Satellite visual images have a greater impact on people than just words, and this shows the importance of Landsat imagery and satellite images in general. [29]
The Yellowstone fires of 1988 were the worst in the recorded history of the national park. They lasted from 14 June to 11 September 1988, when rain and snow helped halt the spread of the fires. The area affected by the fire was estimated to be 3,213 square kilometers – 36% of the park. Landsat imagery was used for the area estimation, and it also helped determine the reasons why the fire spread so quickly. Historic drought and a significant number of lightning strikes were some of the factors that created conditions for the massive fire, but anthropogenic actions amplified the disaster. On images generated previous to the fire, there is an evident difference between lands that display preservation practices and the lands that display clear cut activities for timber production. These two type of lands reacted differently to the stress of fires, and it is believed that that was an important factor on the behavior of the wildfire. Landsat imagery, and satellite imagery in general, have contributed to understanding fire science; fire danger, wildfire behavior and the effects of wildfire on certain areas. It has helped understanding of how different features and vegetation fuel fires, change temperature, and affect the spreading speed. [30] [31]
The serial nature of Landsat missions and the fact that is the longest-running satellite program gives it a unique perspective to generate information of Earth. Glacier retreat in a big scale can be traced back to previous Landsat missions, and this information can be used to generate climate change knowledge. The Columbia glacier retreat for example, can be observed in false-composite images since Landsat 4 in 1986. [32]
Landsat imagery gives a time-lapse like series of images of development. Human development specifically, can be measured by the size a city grows over time. Further than just population estimates and energy consumption, Landsat imagery gives an insight of the type of urban development, and study aspects of social and political change through visible change. In Beijing for example, a series of ring roads started to develop in 1980s following the economic reform of 1970, and the change in development rate and construction rate was accelerated in these time periods. [32]
In 2005, Landsat imagery assisted in the discovery of new species. Conservation scientist Julian Bayliss wanted to find areas that could potentially become conservation forests using Landsat generated satellite images. Bayliss saw a patch in Mozambique that until then had no detailed information. On a reconnaissance trip, he found great diversity of wildlife as well as three new species of butterflies and a new snake species. Following his discovery, he continued to study this forest and was able to map and determine the forest extent. [33]
Landsat 8 launched on 11 February 2013. It was launched on an Atlas V 401 from Vandenberg Air Force Base by the Launch Services Program. It will continue to obtain valuable data and imagery to be used in agriculture, education, business, science, and government. The new satellite was assembled in Arizona by Orbital Sciences Corporation.
Landsat 9 launched on September 27, 2021. During FY2014 financial planning "appropriators chided NASA for unrealistic expectations that a Landsat 9 would cost US$1 billion, and capped spending at US$650 million" according to a report by the Congressional Research Service. United States Senate appropriators advised NASA to plan for a launch no later than 2020. [7] In April 2015, NASA and the USGS announced that work on Landsat 9 had commenced, with funding allocated for the satellite in the president's FY2016 budget, for a planned launch in 2023. [34] Funding for the development of a low-cost thermal infrared (TIR) free-flying satellite for launch in 2019 was also proposed, to ensure data continuity by flying in formation with Landsat 8. [34]
In the future, there may also be more collaboration between Landsat satellites and other satellites with similar spatial and spectral resolution, such as the ESA's Sentinel-2 constellation. [35]
Landsat Next is planned to launch in late 2030/early 2031 and will measure 26 spectral bands; current Landsat's 8 and 9 measure 11 each. [36]
Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Earth and other planets. Remote sensing is used in numerous fields, including geophysics, geography, land surveying and most Earth science disciplines. It also has military, intelligence, commercial, economic, planning, and humanitarian applications, among others.
Landsat 1 (LS-1), formerly named ERTS-A and ERTS-1, was the first satellite of the United States' Landsat program. It was a modified version of the Nimbus 4 meteorological satellite and was launched on July 23, 1972, by a Delta 900 rocket from Vandenberg Air Force Base in California.
The Moderate Resolution Imaging Spectroradiometer (MODIS) is a satellite-based sensor used for earth and climate measurements. There are two MODIS sensors in Earth orbit: one on board the Terra satellite, launched by NASA in 1999; and one on board the Aqua satellite, launched in 2002. MODIS has now been replaced by the VIIRS, which first launched in 2011 aboard the Suomi NPP satellite.
Landsat 7 is the seventh satellite of the Landsat program. Launched on 15 April 1999, Landsat 7's primary goal is to refresh the global archive of satellite photos, providing up-to-date and cloud-free images. The Landsat program is managed and operated by the United States Geological Survey, and data from Landsat 7 is collected and distributed by the USGS. The NASA WorldWind project allows 3D images from Landsat 7 and other sources to be freely navigated and viewed from any angle. The satellite's companion, Earth Observing-1, trailed by one minute and followed the same orbital characteristics, but in 2011 its fuel was depleted and EO-1's orbit began to degrade. Landsat 7 was built by Lockheed Martin Space Systems.
Satellite images are images of Earth collected by imaging satellites operated by governments and businesses around the world. Satellite imaging companies sell images by licensing them to governments and businesses such as Apple Maps and Google Maps.
Landsat 5 was a low Earth orbit satellite launched on March 1, 1984, to collect imagery of the surface of Earth. A continuation of the Landsat Program, Landsat 5 was jointly managed by the U.S. Geological Survey (USGS) and the National Aeronautics and Space Administration (NASA). Data from Landsat 5 was collected and distributed from the USGS's Center for Earth Resources Observation and Science (EROS).
Landsat 4 is the fourth satellite of the Landsat program. It was launched on July 16, 1982, with the primary goal of providing a global archive of satellite imagery. Although the Landsat Program is managed by NASA, data from Landsat 4 was collected and distributed by the U.S. Geological Survey. Landsat 4 science operations ended on December 14, 1993, when the satellite lost its ability to transmit science data, far beyond its designed life expectancy of five years. The satellite housekeeping telemetry and tracking continued to be maintained by NASA until it was decommissioned on June 15, 2001.
Landsat 3 is the third satellite of the Landsat program. It was launched on March 5, 1978, with the primary goal of providing a global archive of satellite imagery. Unlike later Landsat satellites, Landsat 3 was managed solely by NASA. Landsat 3 decommissioned on September 7, 1983, beyond its design life of one year. The data collected during Landsat 3's lifetime was used by 31 countries. Countries that cannot afford their own satellite are able to use the data for ecological preservation efforts and to determine the location of natural resources.
Multispectral imaging captures image data within specific wavelength ranges across the electromagnetic spectrum. The wavelengths may be separated by filters or detected with the use of instruments that are sensitive to particular wavelengths, including light from frequencies beyond the visible light range, i.e. infrared and ultra-violet. It can allow extraction of additional information the human eye fails to capture with its visible receptors for red, green and blue. It was originally developed for military target identification and reconnaissance. Early space-based imaging platforms incorporated multispectral imaging technology to map details of the Earth related to coastal boundaries, vegetation, and landforms. Multispectral imaging has also found use in document and painting analysis.
Colvocoresses Reef is a wholly submerged atoll in the Indian Ocean. It is located in the northeastern part of the Chagos Archipelago, near Speakers Bank and Blenheim Reef. The reef is 8 km long, and measures 1 to 2 km across. Breakers are visible only during heavy seas.
The normalized difference vegetation index (NDVI) is a widely-used metric for quantifying the health and density of vegetation using sensor data. It is calculated from spectrometric data at two specific bands: red and near-infrared. The spectrometric data is usually sourced from remote sensors, such as satellites.
Landsat 2 is the second satellite of the Landsat program. The spacecraft originally carried a designation of ERTS-B but was renamed "Landsat 2" prior to its launch on January 22, 1975. The objective of the satellite was to acquire global, seasonal data in medium resolution from a near-polar, Sun-synchronous orbit. The satellite, built by General Electric, acquired data with the Return Beam Vidicon (RBV) and the Multispectral Scanner (MSS). Despite having a design life of one year, Landsat 2 operated for over seven years, finally ceasing operations on February 25, 1982.
The Multispectral Scanner (MSS) is one of the Earth's observing sensors introduced in the Landsat program. A Multispectral Scanner was placed aboard each of the first five Landsat satellites.
Landsat 8 is an American Earth observation satellite launched on 11 February 2013. It is the eighth satellite in the Landsat program; the seventh to reach orbit successfully. Originally called the Landsat Data Continuity Mission (LDCM), it is a collaboration between NASA and the United States Geological Survey (USGS). NASA Goddard Space Flight Center in Greenbelt, Maryland, provided development, mission systems engineering, and acquisition of the launch vehicle while the USGS provided for development of the ground systems and will conduct on-going mission operations. It comprises the camera of the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS), which can be used to study Earth surface temperature and is used to study global warming.
The Operational Land Imager (OLI) is a remote sensing instrument aboard Landsat 8, built by Ball Aerospace & Technologies. Landsat 8 is the successor to Landsat 7 and was launched on February 11, 2013.
Multispectral remote sensing is the collection and analysis of reflected, emitted, or back-scattered energy from an object or an area of interest in multiple bands of regions of the electromagnetic spectrum. Subcategories of multispectral remote sensing include hyperspectral, in which hundreds of bands are collected and analyzed, and ultraspectral remote sensing where many hundreds of bands are used. The main purpose of multispectral imaging is the potential to classify the image using multispectral classification. This is a much faster method of image analysis than is possible by human interpretation.
IRS-1A, Indian Remote Sensing satellite-1A, the first of the series of indigenous state-of-art remote sensing satellites, was successfully launched into a polar Sun-synchronous orbit on 17 March 1988 from the Soviet Cosmodrome at Baikonur. IRS-1A carries two sensors, LISS-1 and LISS-2, with resolutions of 72 m (236 ft) and 36 m (118 ft) respectively with a swath width of about 140 km (87 mi) during each pass over the country. Undertaken by the Indian Space Research Organisation (ISRO). It was a part-operational, part-experimental mission to develop Indian expertise in satellite imagery.
IRS-1B, Indian Remote Sensing satellite-1B, the second of the series of indigenous state-of-art remote sensing satellites, was successfully launched into a polar Sun-synchronous orbit on 29 August 1991 from the Soviet Cosmodrome at Baikonur. IRS-1B carries two sensors, LISS-1 and LISS-2, with resolutions of 72 m (236 ft) and 36 m (118 ft) respectively with a swath width of about 140 km (87 mi) during each pass over the country. It was a part-operational, part-experimental mission to develop Indian expertise in satellite imagery. It was a successor to the remote sensing mission IRS-1A, both undertaken by the Indian Space Research Organisation (ISRO).
Landsat 9 is an Earth observation satellite launched on 27 September 2021 from Space Launch Complex-3E at Vandenberg Space Force Base on an Atlas V 401 launch vehicle. NASA is in charge of building, launching, and testing the satellite, while the United States Geological Survey (USGS) operates the satellite, and manages and distributes the data archive. It is the ninth satellite in the Landsat program, but Landsat 6 failed to reach orbit. The Critical Design Review (CDR) was completed by NASA in April 2018, and Northrop Grumman Innovation Systems (NGIS) was given the go-ahead to manufacture the satellite.
Virginia Tower Norwood was an American aerospace engineer, inventor, and physicist. She was best known for her contribution to the Landsat program, having designed the Multispectral Scanner which was first used on Landsat 1. She has been called "The Mother of Landsat" for this work.