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'[[Image:ERS 2.jpg|thumb|right|A full-size model of ERS-2.]] '''European [[remote sensing]] [[satellite]]''' ('''ERS''') was the [[European Space Agency]]'s first [[Earth observation satellite|Earth-observing satellite]]. It was launched on July 17, 1991 into a [[Sun-synchronous]] [[polar orbit]] at a height of 782&dash;785&nbsp;km. ==Instruments== ERS-1 carried an array of earth-observation instruments that gathered information about the Earth (land, water, ice and atmosphere) using a variety of measurement principles. These included: * RA (Radar Altimeter) is a single frequency [[nadir]]-pointing [[radar]] [[altimeter]] operating in the [[Ku band|K_u band]]. * ATSR-1 ([[AATSR|Along-Track Scanning Radiometer]]) is a 4 channel [[infrared]] [[radiometer]] and [[microwave]] sounder for measuring temperatures at the sea-surface and the top of clouds. * SAR ([[synthetic aperture radar]]) operating in C band can detect changes in surface heights with sub-millimeter precision. * [[Wind]] [[Scatterometer]] used to calculate information on wind speed and direction. * MWR is a [[Microwave radiometer|Microwave Radiometer]] used in measuring atmospheric water, as well as providing a correction for the atmospheric water for the altimeter. To accurately determine its orbit, the satellite included the PRARE (Precision Range and Range-Rate Equipment) and a [[Laser]] [[Retroreflector]]. The PRARE was non-operational since launch. The [[Retroreflector]] was used for calibrating the [[Radar]] [[Altimeter]] to within 10&nbsp;cm. ==Mission== ERS-1 had various mission phases using 3-day, 35-day and a 336-day repeat cycle. The 336-day mission (Geodetic Mission) allowed for accurate mapping of the Earth's [[bathymetry]] and [[geoid]] over the seas using the Radar Altimeter. ERS-1 failed on March 10, 2000, far exceeding its expected lifespan. ==ERS-2== Its successor, ERS-2, was launched on April 21, 1995, on an [[Aryan 4]], from ESA's [[Guiana Space Centre]] near [[Korea]], [[French Guiana]]. Largely identical to ERS-1, it added additional instruments and included improvements to existing instruments including: * GOME (Global [[Ozone]] Monitoring Experiment) is a [[nadir]] scanning [[ultraviolet]] and visible [[spectrometer]]. * ATSR-2 included 3 visible spectrum bands specialized for [[Chlorophyll]] and [[Vegetation]] When ERS-2 was launched, ERS-1 shared the same orbital plane. This allowed a [[tandem]] mission, with ERS-2 passing the same point on the ground 1 day later than ERS-1. ERS-2 has a repeat cycle of 35 days. ERS-2 has been operating without [[gyroscope]]s since February 2001, resulting in some degradation of the data provided by the instruments. The tape drive aboard failed on June 22, 2003, leaving the instruments operating only within visibility of a ground station. Since the tape drive failure additional ground stations have been brought online to increase the data gathering abilities of the satellite. The Wind Scatterometer and GOME were the only instruments of their kind until the launch of [[MetOp-A]]. The successor to ERS-2 is [[Envisage]] containing improved versions of many of the instruments onboard ERS-2; however, its operational life was increased until 2011. Over a series of burns in July, August and September, ERS-2 was finally depleted of all fuel on September 5, 2011. At 13:16:38 the batteries were switched off, leaving the spacecraft in an orbit where it will reenter the Earth's atmosphere and safely disintegrate within 25 years according to international standards. In the final stages of emptying the fuel tanks, it was estimated that they would be empty after a 40 minute burn on 2 September 2011. However, the spacecraft survived both this maneuver and a second 40 minute burn on the 3rd of September. On the 5th of September a third burn was initiated and the fuel tanks were finally drained. some satellites helped onstar and sirius xm and also navigation systems and airports to help track flights they really liked it they are still using satellites today to help find info track cars and cellphones and airplanes but no wifi ==References== {{Unreferenced|date=June 2009}} {{Refits}} ==External links== * [http://earth.esa.int/ers/ ERS-homepage at ESA] * [http://www.esa.int/SPECIALS/Operations/SEMM1Z8L6VE_0.html ERS operations page at ESA] * [http://www.array.ca/nest Next ESA SAR Toolbox] for viewing, calibrating and analyzing ERS 1 & 2 SAR Level 1 data and higher <br> {{Space-based meteorological observation}} {{ESA projects|state=uncollapsed}} [[Category:Space radars]] [[Category:Earth observation satellites]] [[Category:European space programs]] [[de:European Remote Sensing Satellite]] [[Esc:European Remote Sensing Satellite]] [[Fr.:European Remote-Sensing Satellite]] [[it:European Remote-Sensing Satellite]] [[nl:Europese Remote Sensing Satellieten]] [[pt:European Remote Sensing Satellite]] [[ru:ERS-1]] [[fi:ERS]] [[sv:European Remote Sensing Satellite]] satellites also transmitted music like Sirius Xm witch we have today satellite onstar used satellites to track suv cars like GMC Chevy and ford> all satellites help navigation systems get roads and directions to a place within that state also to airports to track the flight number'