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Surveillance satellite systems provide multispectral remote sensing from space for Earth resources management applications, and intelligence collection purposes. An important aspect of surveillance satellites is the resolution of the images provided. Click on the image below for an example of various image resolutions.
A civil satellite system developed in the 1960s by NASA, the first Landsat satellite was launched in 1972. Since then, four more have been launched; the latest versions contain a multispectral (green to near infrared) scanner with an 80 meter resolution, and a thematic mapper, which can resolve objects down to 25 meters. European Space Agency ground receiving stations can gather Landsat data; a company called Eurimage distributes this data, with a rush order time for images taking about five days for production and delivery. Landsat satellites have a circular, sun-synchronous, near-polar low earth orbit, with an altitude of 705 km; after 16 days, each satellite returns to its starting point and repeats the ground trace. [1] Because of the importance of multispectral imagery during the Gulf War, future Landsats will be co-managed by the Department of Defense and NASA; enhanced sensors capable of 5-meter stereoscopic images are expected in the next Landsat. [2]
France, Belgium, and Sweden sponsor the Earth observation program called SPOT. [3] CNES (Centre National d’Etudes Spatiales), France’s space agency, is responsible for the ownership and operation of the SPOT system, while private companies run the worldwide commercial operations (like SPOT IMAGE Corp in the US). [4] The first SPOT was launched in 1986; two others followed; a fourth SPOT is scheduled for launch late in 1997. [5] The latest SPOT will carry two high resolution, visible imaging instruments, capable of 10 meter resolution in the panchromatic band and 20 meter resolution in the multispectral bands; a new medium infrared channel will support vegetation analysis and harvest forecasting. SPOT satellites have a repetitive, circular, sun synchronous, near polar low earth orbit, with an altitude of 832 km. SPOT #5, projected for launch in 2001, will be capable of 5 meter resolution in the panchromatic mode, and 10 meters multispectral. [6]
The two ERS spacecraft in orbit provide the European Space Agency with global measurements of the earth’s atmospheric and surface properties using radar. The payload produces numerous measurements including sea-surface wind-speed/direction, sea-surface height, wave height, sea-surface temperature, cloud-top temperature, atmospheric water vapor, and radar images of land, ice, and ocean regions. ERS satellites fly in a polar sun-synchronous low earth orbit at 780 km altitude. The second ERS satellite was placed in an orbit which repeats itself every 35 days, with a 1-day separation from the first ERS, permitting it to pass within 200 meters of the first ERS satellite overflight position. Processing and archiving facilities are located in the United Kingdom, Italy, Germany, and France. ERS is capable of 30 meter resolution. [7]
Pakistan has jumped into the world of nations with remote sensing satellite systems with BADR-2. The satellite is very small, weighing only about 46 kg, and will fly in a low earth orbit of 1000 km altitude. It will carry a charge-coupled device camera for cloud monitoring, operating at visible wavelengths, with an aim of achieving 250 meter resolution. [8]
India has been heavily engaged in the reconnaissance/earth resources game lately—one estimate has them launching ten remote sensing satellites in the period between 1995-2005. IRS-1C is their latest design—launched by Glavkosmos, Russia’s commercial space organization, in late 1995. IRS-1C has a reputed 6 meter resolution panchromatic camera and a 20 meter resolution multispectral camera. IRS-1C is in a sun-synchronous low earth orbit at an altitude of 817 km. Eosat, an American company, will commercially distribute IRS data; its ground station at Norman, Oklahoma was reportedly the first to receive IRS data outside India. [9]
Japan has several satellites in the reconnaissance/earth resources genre. JERS’ mission is to provide global, all-weather imaging capability for agriculture, forestry, fishery, environmental protection, and disaster protection use. JERS has a synthetic aperture radar capable of 18 meter resolution, and an optical sensor with stereoscopic imaging that measures light reflected from the earth’s surface ranging from visible to shortwave infrared, also at 18 meter resolution. JERS flies in a circular, sun-synchronous low earth orbit at 568 km altitude and has a 44 day repeat period. [10] First launched in 1992, JERS provides observation data to both Japanese and foreign users. [11]
Japan’s two MOS satellites monitor ocean currents, sea surface temperature, atmospheric water vapor, ocean chlorophyll levels, precipitation, and land vegetation. Payloads include the Multispectral Electronic Self-Scanning Radiometer (MESSR) with 50 meter resolution, the Visible and Thermal Infrared Radiometer (VTIR) covering six visible to infrared bands, and the Microwave Scanning Radiometer (MSR) with 23-32 km resolution. MOS flies in a sun-synchronous low earth orbit at 909 km altitude with a repeating ground trace of 17 days. [12] MOS image data is processed and distributed to universities, research institutes, and other foreign users. [13] Three more MOS missions are planned. [14]
Japan’s ALOS performs high resolution observation of the earth’s surface for map-making activities. Other uses include monitoring and preventing ecological disasters, environmental protection, and for maintaining and developing earth observation technology. ALOS payloads consist of an advanced visible near-infrared radiometer, a synthetic aperture radar for imaging regardless of weather conditions, and a data collection system. ALOS flies in a sun synchronous low earth orbit of 700 km altitude. [15]
The Chinese FY program currently consists of two polar orbiting meteorological satellites (FY-1A and FY-1B) with some limited reconnaissance capabilities. Launched in 1988 and 1990, the two satellites orbit low to the earth at an altitude of 870 km. The FY-1 class includes a multichannel visible and infrared scan radiometer capable of detecting visible to long wave infrared radiation; FY-1 can monitor forest fires, vegetation, sea surface temperature, ice and snow cover, river mouth silt sedimentation, atmospheric temperature and humidity. Two additional FY-1 series satellites will be launched by 1999. The first in the FY-2 series is scheduled for launch before 1998, and will be inserted into a geostationary orbit at an altitude of 35,800 km over 105 degrees East. FY-2 will include visible, infrared, and water vapor channels; from raw cloud image data, many kinds of image and meteorological parameters can be processed. [16]
China and Brazil agreed in 1988 to cooperatively build two remote sensing satellites—the result is CBERS, a multi-sensor payload with different spatial resolutions and data collecting frequencies. Payloads include the Wide Field Imager, covering the green to near-infrared spectral bands, a high resolution charge-coupled device camera providing 20 meter resolution stereoscopic images, and an infrared multispectral scanner. CBERS includes a data collection system for real-time retransmission of environmental data gathered on the ground and transmitted to the satellite by small autonomous stations. CBERS has a sun-synchronous low earth orbit at an altitude of 778 km; it takes 26 days to revisit the same earth location. Both Brazil and China have image receiving stations and processing centers; other countries can establish stations as well. [17]
Several commercial imagery satellite systems are expected to surface in the coming years. World View, capable of 3 meter resolution; Eyeglass, with 1 meter; and Space Imaging, Inc., also with 1 meter resolution, are all expected to be operational by the year 2000, selling images on the open market. In addition, the European Envisat (for Environmental Satellite) program is expected to launch by 2000 as well, and will improve upon its SPOT/ERS imaging heritage. Canada’s Radarsat satellite is already in orbit, providing a resolution between 10-100 meters. Finally, the Russian Almaz program, previously used by the military, has been identified as another imaging system to soon sell its 5 meter resolution photographs on the commercial market. [18]
[1] Eurimage, LANDSAT, (Rome, Italy: Eurimage, 29 January 1997), http://www.eurimage.it/Products/Landsat.html. [Return]
[2] Michael Muolo, Major, Space Handbook, Vol. One, (Air University Press, December 1993), 85. [Return]
[3] California Institute of Technology, Jet Propulsion Laboratory, "SPOT Quick Look," Mike’s Spacecraft Library, (New Space Network, 24 April 1996), http://leonardo.jpl.nasa.gov/msl/Quicklooks/spot4QL.html. [Return]
[4] SPOT Image, "SPOT System," SPOT Home Page, (SPOT Image, 10 February 1997), http://www.spotimage.com.au/anglaise/system/s_syst.htm. [Return]
[5] "SPOT Quick Look," Mike’s Spacecraft Library, http://leonardo.jpl.nasa.gov/msl/Quicklooks/spot123QL.html. [Return]
[6] US Geological Survey Office, "SPOT," EROS Home Page, (US Geological Survey Office, January 1997), http://edcwww.cr.usgs.gov/glis/hyper/guide/spot/address/addresses. [Return]
[7] "D/OPS Missions," European Space Agency Home Page, (ESA, 14 September 1996), http://www.esoc.esa.de/external/mso/ers.html. [Return]111
[8] Janet Cathell, TASC Report, (9 February 1996). [Return]
[9] Tag’s Broadcasting Services, "IRS 1C Satellite Fact Sheet," The Satellite Encyclopedia, (Tag’s Broadcasting Services, 25 January 1997), http://www.tele-satellit.com/tse/online/sat_irs_1c.html. [Return]
[10] "JERS Quick Look," Mike's Spacecraft Library, http://leonardo.jpl.nasa.gov/msl/QuickLooks/jersQL.html. [Return]
[11] Earth Observation Systems, "Japanese Earth Resources Satellite JERS-1 [Fuyo-1]," This is NASDA, (Earth Observation Systems, 26 February 1997), http://yyy.tksc.nasda.go.jp/Home/This/This-e/jers_e.html. [Return]
[12] "MOS1A, 1B Quick Look," Mike's Spacecraft Library, http://leonardo.jpl.nasa.gov/msl/QuickLooks/mosQL.html. [Return]
[13] "Marine Observation Satellite MOS-1/MOS-1b [Momo-1/Momo-1b]," This is NASDA, http://yyy.tksc.nasda.go.jp/Home/This/This-e/mos_e.html. [Return]
[14] TELSAT, MOS Programme, (27 January 1995), http://www.belspo.be/telsat/mos/mopg_001.htm. [Return]
[15] "Advanced Land Observing Satellite, ALOS," This is NASDA, http://yyy.tksc.nada.go.jp/Home/This/This-e/alos_e.html. [Return]
[16] "Peoples Republic of China (PRC) National Satellite Meteorological Center," EROS Home Page, http://edcwww.cr.usgs.gov/china/china.htm. [Return]
[17] "CBERS Info," Instituto Nacional de Pesquisas Espaciais (INPE), (Image Generation Division, 7 May 1996), http://www.dgi.inpe.br/html/eng/cbers.htm. [Return]
[18] Lamont Harvey, "Many Nations Feed Commercial Imagery Market," Space News, (March 6-12, 1995), 9. [Return]