Minimize Disclaimer

Please note that the Envisat mission ended on 08 April 2012, following the unexpected loss of contact with the satellite. (See related news from 09 May 2012)

The ERS-1 mission ended on 10 March 2000 and ERS-2 was retired on 05 September 2011

The details below are presented for historical and technical purposes, for the information of data users. 

Minimize Specific Instrument Planning - Envisat

ASAR has 5 modes of operations: ASAR Image Mode, ASAR Alternating Polarization Mode, ASAR Wide Swath Mode, ASAR Globlal Monitoring Mode and ASAR Wave Mode, being the first three high bit rate modes and the remaining low bit rate modes. All these modes are mutually exclusive: at a single time, the ASAR instrument can only be operated with a single mode and sub-mode (i.e. unique imaging swath and polarisation).

Fixed planning and 'user on-demand' planning

The ASAR Low Bit Rate is used following a predefined and systematic planning; ASAR Global Monitoring mode over land and polar areas and ASAR Wave mode over oceans, when the instrument is not operated in High Rate mode. ASAR is operated according to a predefined Background Mission (BM) for ASAR low bit rate modes.

The ASAR High Bit Rate is operated according to user demand. In case of no user demand for a particular time slot, ASAR is operated according to predefined Background Regional Mission (BRM) for ASAR high bit rate modes.

During the period immediately following the Envisat orbital change of October 2010, the ASAR high Bit Rate is operated using a pre-defined observation scenario; this is for a period up to 3 month with a temporary reduced capacity

View new maps of the acquisitions

Background Regional Mission (BRM)

The aim of the BRM is to systematically cover some areas in the operations mode most requested by the user community and to fully exploit the resources of the satellite.

For example:

MERIS FR over Europe, Australia and Asia
ASAR WS over Africa (descending passes only)
ASAR European coverage in IM IS6 H/H
ASAR ASAR IS IS6 H/H over tectonic sites around 38°N on descending passes and 38° S on ascending passes
ASAR polarisation combinations at various incidence angle on a set of selected sites worldwide (over volcanoes, earthquakes, etc)
ASAR Wide Swath world coverage of land and ice masses


While performing the instruments planning, the Mission Planners have to cope with the following system constraints:
  • The ASAR can be operated for a maximum of 30 minutes per orbit, including 10 minutes in eclipse, segmented in a maximum of 10 HR segments, each one having a minimum duration, depending on the instrument mode (40 to 50 seconds) and a maximum duration of 10 minutes
  • There is a transition time to be taken into account between ASAR operation modes
  • The 37 ASAR operating modes are mutually exclusive
  • Regarding the on-board Recorders (SSR): ASAR HBR and MERIS FR data cannot be recorded simultaneously
  • ASAR HBR cannot be downlinked in real time simultaneously with SSR dump of ASAR data

More information on what is planned in the BM and in the BRM click here

Minimize Specific Instrument Planning - ERS

The SAR Wave Mode is switched on by default for the orbit segments in which the SAR Image Mode is not switched on, unless descoping is required due to limited tape recorder capacity or ATSR-2 high resolution activity.

Click here for detailed information on the planning of the SAR instrument.