Envisat-1: Mission Support
Jump to: Mission Support Status, Current Tracking Statistics, Mission Support Request
ILRS Mission Support Status:
Envisat Mission support was approved by the ILRS Governing Board in March 2001. Satellite laser ranging data are combined with DORIS data and used for Precision Orbit Determination (POD), which is required to calibrate the on-board altimeter. The altimeter data is used to determine ocean surface heights. This ocean height data, in turn, is used to monitor global ocean circulation, regional ocean current systems, and study the marine gravity field.
Envisat-1 is regularly tracked by the ILRS network.
Envisat Mission Support Request Form (10 February 2000, updated March 2001):
Name: ENVISAT
Host: ESA
Primary Techical Contact: POD: Patrick Vincent
Alternate Technical Contact: POD: Berthyl Duesmann
Technical Mailing Address: Patrick Vincent, CNES - DSO/ED/AL/MA, 18 Avenue
E. Belin 31401 Toulouse Cedex 4, France
Technical email: Patrick.Vincent@cnes.fr
Technical Fax: 33 5 61 28 25 95
Technical Web_Address: www.envisat.jw.estec.esa.nl
Primary Science Contact: POD: Rene Zandbergen
Alternate Science Contact: POD: Jean Paul Berthias
Science Mailing Address: Rene Zandbergen, ESOC/ESA, Robert-Bosch
Strasse 5, D-64293 Darmstadt, Germany
Science Fax: 00 49 61 51 90 495
Science email: Rene.Zandbergen@esa.int
Mission objectives: Introduction
The main objective of the Envisat programme is to endow Europe with an enhanced capability for the remote sensing observation of Earth from space, with the aim of further increasing the capacity of participating states to take part in the studying and monitoring of the Earth and its environment.
Its primary objectives are: - 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 to increase 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).
These are coupled with two linked secondary objectives: - to allow more effective monitoring and management of the Earth's resources; - to better understand solid Earth processes.
The mission intends to continue and improve upon measurements initiated by ERS-1 and ERS-2, and to take into account the requirements related to the global study and monitoring of the environment.
The mission is an essential element in providing long-term continuous data sets that are crucial for addressing environmental and climatological issues. It will at the same time further promote the gradual transfer of applications of remote sensing data from experimental to poperational and operational exploitation.
Envisat, as an undertaking of ESA member states plus Canada, constitutes a major contribution to the international effort of space agencies worldwide to provide the data and information required to further the understanding, modeling, and pdiction of environmental and climatic changes.This mission includes both global and regional mission objectives (see below) with the corresponding need to provide data to scientific and applications (see below) users on various time scales.
Global mission objectives:
Continuous and coherent global data sets are needed by the scientific and application community in order to understand better climatic processes and to improve climate models.
Some global applications require near real time data delivery (from a few hours to one day from sensing). Specific examples include:
- 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, pssure, and water vapour, cloud top height, earth radiation budget, etc.);
- monitoring of ocean color for supporting fisheries and pollution monitoring (complementing the regional mission).
Some of the global objectives require products available in off-line mode (days to weeks from sensing). Specific examples include quantitative monitoring of:
- 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.).
Regional mission objectives:
Continuous and coherent regional data sets are needed by the scientific and application user community for a variety of objectives such as:
- 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
Some of the regional objectives (e.g., sea ice applications, marine pollution, maritime traffic, hazard monitoring, etc.) require near real time data products (within a few hours from sensing) generated according to user requests. Some other of these objectives (e.g., agriculture, soil moisture, etc.) require fast turnaround data services (a few days). The remainder would be satisfied with off-line (few weeks) data delivery.
Mission role: A Laser retroreflector will be mounted on a pillar attached to the nadir panel close to the RA_2 altimeter antenna. It has two functions:
- Support to POD
- RA-2 Range bias calibration
Launch date: July 2001
Mission duration: 5 Years
Altitude: 796.128 km (a: 7159.496 km)
Inclination: i: 98.54
Eccentricity: e: 0.001165
Tracking sched: To be detailed
Spatial coverage: Global, with an emphasis on Europe
Temporal coverage: During complete mission, with an emphasis on the
commissioning phase (from launch till 6 months after launch)
Data accuracy: High for commissioning phase
Coordinator: ILRS
Priority: High priority during DORIS & RA-2 calibration and validation
POD source: DORIS and SLR, (RA-2)
Analysis Center: POD: CNES
Normal point time span: 15 sec (ERS heritage, TBC)
Tracking requests: Global tracking needed
Array info: To be supplied
Technical contact for array info: Berthyl Duesmann
Array contact number: Berthyl.Duesmann@esa.int / 00 31 71 5654414
Comments: The corner cubes are made of the highest-quality fused silica and work in the visible spectrum. Their performance is optimised at the two wavelengths(694 nm and 532 nm) commonly used in SLR stations. The corner cubes are symmetrically mounted on a hemispherical surface with one nadir-looking corner cube in the centre, surrounded by an angled ring of eight corner cubes.
This will allow laser ranging in the field of view angles of 360 in azimuth and 60 elevation around the perpendicular to the satellite's -Zs Earth panel.
The design is identical to the very successful reflectors used on ERS-1 and ERS-2.
