1. ENVISAT
Burcu Bölükbaşı
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2. Overview
Introduction
Mission and System
History
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3. Introduction Launched by the European Space Agency in March, 2002.
Measurements of the atmosphere, ocean, land, and ice.
Continuity of the data measurements of the ESA ERS satellites.
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4. Earth science research
Monitoring of the evolution of the environmental and climatic changes
Development of operational and commercial applications
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5. Mission and System
The Envisat Space Segment (the satellite itself) including the Polar Platform (PPF) and the payload
The Envisat Ground Segment consisting of the payload data segment (PDS) and the flight operation segment (FOS)
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6.
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7. ARTEMIS (Advanced Relay and Technology Mission Satellite)
Testing
Operating
New technology systems
Launched on 12 July 2001.
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8. Explore advanced technology to transmit data directly from one satellite to another
Observation satellites in low orbit like ERS must use on-board recording and global networks of ground stations
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9. Two payloads for communications directly between satellites:
Receive data from low-Earth orbiting satellites
Transmit them directly to Europe
L-band land mobile payload allows two-way communications, via satellite, between fixed Earth stations and land mobiles - trucks, trains or cars - anywhere in Europe and North Africa.
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10.
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11.
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12. ARTEMIS Coverage
High and low rate data, including recorder playback, can be received under the Artemis coverage (the on-board Ka-band transmit terminal and data reception with the User Earth Terminal (UET) at ESRIN).
The establishment of the link between the Envisat and Artemis satellites may require up to 3 minutes.
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13. The Ten-thousandth Orbit
The satellite completed its 10,000th orbit in 28 January 2004.
Traveled 450 million kilometers since its launch
Envisat was using all its ten instruments to gather information about the earth and the ground segment was generating about 10,000 Megabytes of data products.
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14. SCIAMACHY total ozone column:
Instrument: Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY)
Date of Acquisition: 28 January 2004
Orbit number: 10000
Orbit direction: Descending
SCIAMACHY product used: Level 1 spectra
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15. ASAR Global Monitoring Mode over Arctic Sea, north of Greenland:
Instrument: Advanced Synthetic Aperture Radar (ASAR)
Date of Acquisition: 28 January 2004
Orbit number: 10000
Orbit direction: Descending
ASAR features: Global Monitoring Mode image (1000 meter resolution)
ASAR mode: Global Monitoring Mode (400 km wide)
ASAR polarization: HH
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16.
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17. Synthetic Aperture Radar (SAR)
Technical Information:
Instrument: Synthetic Aperture Radar (SAR)
Dates of Acquisition: Red: 15 July 2004, Green: 6 May 2004, Blue: 22 January 2004
Orbit numbers: 48286, 47284, 45781
Frame: 2781
Instrument features: 25 meter resolution
Coordinates: NE Lat/Long: N / E NW Lat/Long: N / E SW Lat/Long: N / E SE Lat/Long: N / E 29.60
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18. MERIS (Medium Resolution Imaging Spectrometer)
Technical Information:
Instrument: Medium Resolution Imaging Spectrometer (MERIS)
Date of Acquisition: 18 November 2004
Orbit number: 14218
Instrument features: FR
Coordinates: NE Lat/Long: N / E NW Lat/Long: N / E SW Lat/Long: N / E SE Lat/Long: N / E 27.97
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19. Advanced Synthetic Aperture Radar (ASAR) Technical Information:
Instrument: Advanced Synthetic Aperture Radar (ASAR)
Dates of Acquisition: Red: 07 June 2004, Green: 06 October 2003, Blue: 15 December 2003
Orbit Direction: Descending
Orbit number: 11870, 8363, 9365
Instrument features: Wide Swath Mode (geometric sampling: 1 pixel=75 m.)
ASAR polarisation: VV
Coordinates: 
NE Lat/Long: N / E 31.00
NW Lat/Long: N / E 26.52
SW Lat/Long: N / E 26.59
SE Lat/Long: N / E 30.54
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20. Instrument: Advanced Synthetic Aperture Radar (ASAR)
ASAR wide Swath Mode over Antarctica, the Ross Sea and giant iceberg B15-A:
Instrument: Advanced Synthetic Aperture Radar (ASAR)
Date of Acquisition: 28 January 2004
Orbit number: 10000
Orbit direction: Descending
ASAR features: Wide Swath Mode image (150 meter resolution)
ASAR mode: Wide Swath Mode (400 km wide)
ASAR polarization: HH
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21. MERIS Reduced Resolution over Texas and Mexico:
Instrument: Medium Resolution Imaging Spectrometer (MERIS)
Date of Acquisition: 28 January 2004
Orbit number: 10000
Orbit direction: Descending
Instrument features: Reduced Resolution image (1200-metre resolution)
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22. AATSR Thermal Image over Baffin Island:
Instrument: Advanced Along Track Scanning Radiometer (AATSR)
Date of Acquisition: 28 January 2004
Orbit number: 10000
Orbit direction: Descending
Instrument features: Level1b (TOA) image (1 kilometre-scale resolution)
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23. OPERATIONS
Envisat flies in a sun-synchronous polar orbit of about 800-km altitude.
The repeat cycle of the reference orbit is 35 days
Provides a complete coverage of the globe within one to three days
MWR and RA-2
ERS-1 and ERS-2
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24. Mission and Operation Requirements
Sun-synchronous polar orbit (SSO): Nominal reference orbit of mean altitude 800 km, 35 days repeat cycle, 10:00 AM mean local solar time (MLST) descending node, deg. inclination.
The orbit is controlled to a maximum deviation of +/- 1 km from ground track and +/- 5 minutes on the equator crossing MLST.
Recording of payload data over each orbit for low bit rate (4.6 Mps) on tape recorders or solid state recorder (SSR).
High rate data (ASAR and MERIS) to be accessible by direct telemetry or recording on SSR.
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25. Global Low Rate Mission and Data Recovery Strategy
General operation concept
continuous operation of the low-rate instruments around the orbit (with the exception of MERIS, which is limited by sun-illumination conditions);
on-board recording of all instrument data;
data-recorder playback at least once per orbit in order to ensure availability of fast delivery products within less than three hours from observation
systematic processing of all acquired data.
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26. Processing and Data Distribution Strategy
Low-rate data is systematically processed on the ground and disseminated to users in near real time (NRT).
All data is reprocessed off-line. Nominal off-line distribution is performed on physical media to registered users.
Small products are available for retrieval on line, with the possibility for users to extract partial data sets.
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27. Regional Mission Operations and Data Decovery Strategy
The regional mission includes the full-resolution mode of MERIS and all modes of the ASAR, with the exception of the wave mode. The following sections provide the basic concepts ruling the operations of the regional mission.
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28. ASAR general operation strategy
ASAR offers, by exploiting the combinations of polarizations and incidence angles, 37 different and mutually exclusive operating modes in high, medium (wide swath mode), and reduced (global monitoring mode) resolution.
ASAR high- and medium-resolution imaging modes are either transmitted on a real time link (direct X-band or via Artemis Ka-band link) or recorded on the on-board solid state recorder for ground data recovery.
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29. ASAR processing and data distribution
Browse products are available on-line.
High-resolution products are processed in near real time or off-line, upon user request.
All medium (and high) resolution products are delivered to users on request either in near real time on a dissemination channel or off line on physical media.
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30. MERIS general operation strategy
MERIS operates at full resolution (FR with 300 m resolution at nadir).
The data are averaged on board to produce a separate data stream at reduced resolution (RR with 1200 m resolution at nadir).
MERIS FR is either transmitted on a real time link (direct X-band or via Artemis Ka-band link) or recorded on the on-board solid state recorder for ground data recovery.
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31. MERIS processing and data distribution
MERIS RR data acquired at ESA facilities is systematically processed in near real time to generate MERIS RR Level 1b and 2 products as well as browse products.
Browse products are available on-line.
Upon user request MERIS FR data is processed and distributed either in near real time (dissemination link) or off-line (physical media).
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32. Regional mission data recovery
data over Europe will be acquired directly via X-band links (Kiruna and Matera coverage),
data outside Europe will be acquired whenever possible via Artemis direct transmission to the UET located at ESRIN,
data outside direct coverage of the ESA X-band stations and Artemis, will be recorded on board using the SSR and acquired via deferred dump to one of the ESA stations via X- or Ka-band links,
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33. data requested by a station operator or by the distributing entities on behalf of a station operator will be transmitted in X-band for acquisition by the corresponding station,
if data to be acquired by a station operator are also needed as part of ESA archive, then in parallel with X-band direct data transmission, ESA will acquire the data via combined use of the SSR, X- or Ka-links as appropriate.
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34. On-board Recording Capability
The on-board recording system is composed of two solid state recorders (SSR) with 70 Gbits capacity each, and one tape recorder (TR), 30 Gbits capacity as back up for low rate data recording.
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35.
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36. Main technical characteristics of the SSR's
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37. Tape Recorder
One tape recorder (TR) onboard ENVISAT capable of recording the low-rate global data.
The recorder allows to record up to 6500 seconds, which is slightly more than one full orbit of LR data recording.
The TR playback dump is performed at 50 Mbps (half-RF channel) via X- or Ka-band links.
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38. On ground data recovery (data dump)
Two selectable data dump rates are usable on X-band and/or Ka-band RF-channels:
50 Mbps (half RF channel) dump of 70 Gbits in 23 min 20 sec.
100 Mbps (full RF channel) dump of 70 Gbits in 11 min 40 sec. (for ASAR HR data only).
Each of the three memory areas can be separately controlled with respect to data dump time and data rate.
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39. Operation strategy and mission impact
One SSR will be used for the global mission, for low rate data recording.
Second SSR will be used for the regional mission (ASAR HR and MERIS FR), with data dump via ARTEMIS to the user Earth terminal (UET).
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40. Data transmission up to two X-band links operating at a time
up to two Ka-band links operating at a time
X- and Ka-band transmitters operate independently, therefore up to two X-band links and two Ka-band links can be operated simultaneously.
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41. Mission Scenarios
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42. Global mission scenario
continuous operation of the low-rate instrument around the orbit (For MERIS, sun-illumination constraints limit the observation to about 43.5 minutes per orbit);
on board recording of all instrument data;
playback at least once per orbit to ensure availability of FD products within less than three hours from observation;
systematic processing of all acquired data.
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43. Regional mission scenario
the ASAR high-rate operations in wide-swath mode and narrow-swath modes
the MERIS full-resolution (FR) mode
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44. The Envisat Orbit
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45. Measurement patterns orbital parameters
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46. Orbit selection
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47. Orbit maintenance
The orbit maintenance requirements are that the deviation of the actual ground track from the nominal one is kept below 1 km and that the mean local nodal crossing time matches the nominal one to better than five minutes.
The orbit maintenance strategy aims for minimum disturbance of the payload operation.
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48.  History
The development of a multimission Polar Platform for future Earth observation missions, initially started as an element of the Columbus Space Station Programme.
The Polar Orbiting Earth Observation Mission (POEM-1), initially conceived as a combined mission with instruments for scientific application, research, and operational meteorology. This mission, to be based on the Polar Platform, was to be the successor of ERS.
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49. The Polar Platform (PPF)
deletion of multimission requirements and related activities for cost saving reasons;
splitting of the first mission POEM-1 into Envisat (the environmental mission) and METOP-1 (the meteorological mission) in mid-1993;
several iterations on cost savings/descoping actions executed in mid-1993, early 1994, and the end of 1995 to reduce overall programme costs in industry and ESA
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50. The mission
The development of the payload instruments for Envisat started after the split of POEM-1 into Envisat and METOP-1 at the Ministerial ESA council meeting in December 1993.
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51. Objectives
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52. Primary Objectives
to provide for continuity of the observations started with the ERS satellites, including those obtained from radar-based observations;
to enhance the ERS mission, notably the ocean and ice mission;
to extend the range of parameters observed to meet the need of increasing knowledge of the factors determining the environment;
to make a significant contribution to environmental studies, notably in the area of atmospheric chemistry and ocean studies (including marine biology).
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53. Secondary Objectives
to allow more effective monitoring and management of the Earth's resources;
to better understand solid Earth processes.
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54. Global mission objectives
Real time data delivery (from a few hours to one day from sensing):
forecasting of the sea state conditions at various scales;
monitoring of sea surface temperature;
monitoring of some atmospheric species (e.g., ozone for warning purposes);
monitoring of some atmospheric variables (e.g., temperature, pressure, and water vapor, cloud top height, earth radiation budget, etc.);
monitoring of ocean color for supporting fisheries and pollution monitoring (complementing the regional mission).
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55. Off-line mode (days to weeks from sensing): radiate processes;
ocean-atmosphere heat and momentum exchange;
interaction between atmosphere and land or ice surfaces;
composition of the atmosphere and associated chemical processes
ocean dynamics and variability;
ice sheet characteristics and sea ice distribution and dynamics;
large-scale vegetation processes in correlation with surface energy and water distribution;
primary productivity of oceans;
natural and man-made pollution over the oceans.
support to large international programmes (GCOS, IGBP, etc.).
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56. Regional mission objectives
sea ice off-shore applications
snow and ice detection and mapping
coastal processes and pollution monitoring
ship traffic monitoring
agricultural and forest monitoring
soil moisture monitoring and large-scale vegetation processes
geological features and mineral resources
application linked to SAR interferometry (DEM generation, hazard monitoring, etc.)
hydrological research and applications
support to fisheries in coastal waters
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57. Instrument contribution to Envisat mission objectives
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58.
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59.
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60.
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61. http://envisat.esa.int/ http://www.temis.nl/
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62. ENVISAT
Burcu Bölükbaşı
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