The MSG payload is designed in accordance with the MSG Mission objectives, in order to accomplish the following functions:
Like the previous generation of Meteosat satellites, MSG is spin-stabilised. When operating in geostationary orbit, the satellite spins counter-clockwise at 100 rpm around its longitudinal axis, which is aligned with the Earth's rotational axis. The MSG satellites are placed in orbit at 0 degrees longitude, like the first generation Meteosats, but can be moved up to 50 degrees East or West if required.
The MSG body is a cylindrical-shaped solar drum, 3.2 m in diameter and 2.4 m high. The satellite itself is built in a modular way around three main sub-assemblies:
The MSG system provides accurate weather monitoring data through its primary instrument — the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) — which has the capacity to observe the Earth in 12 spectral channels.
SEVIRI has twelve spectral channels, as opposed to three on the previous system. These provide more precise data throughout the atmosphere, giving improved quality to the starting conditions for Numerical Weather Prediction models. Eight of the channels are in the thermal infrared, providing, among other information, permanent data about the temperatures of clouds, land and sea surfaces. One of the channels is called the High Resolution Visible (HRV) channel, and has a sampling distance at nadir of 1 km, as opposed to the 3 km resolution of the other visible channels. Using channels that absorb ozone, water vapour and carbon dioxide, MSG satellites also allow meteorologists to analyse the characteristics of atmospheric air masses, making it possible to reconstruct a three-dimensional view of the atmosphere. The improved horizontal image resolution for the visible light spectral channel (1 km as opposed to 2.5 km on the previous system) also greatly aids weather forecasters in detecting and predicting the onset or cessation of severe weather.
Mission Communication Payload (MCP)
This package contains all antennas and transponders necessary to meet the demanding communication needs of the MSG mission. This includes telemetry, telecommanding and transmission relay links, in various frequency bands.
Geostationary Earth Radiation Budget (GERB)
In addition to the SEVIRI, there is the Geostationary Earth Radiation Budget (GERB) instrument. The GERB is a visible-infrared radiometer for Earth radiation budget studies. It makes accurate measurements of the short wave (SW) and long wave (LW) components of the radiation budget at the top of the atmosphere. It is the first ERB experiment from geostationary orbit. The GERB provides valuable data on reflected solar radiation and thermal radiation emitted by the Earth and atmosphere.
Search and Rescue transponder
The Search and Rescue transponder receives distress signals from any mobile unit in difficulty, within the MSG coverage zone in Europe, Africa and the Atlantic Ocean.
The spectral response of an instrument is a measure of the instrument's response to radiation at specific wavelengths. Spectral response characterisation is the most crucial aspect of satellite calibration. The responses are non-linear and may change over the lifetime over an instrument, making it necessary to correct for these changes after launch when producing images from the system. The accuracy of pre-launch spectral response characterisation, and how well the on-orbit changes are understood, directly affects calibration accuracy and the quality of the data products. Even within the same satellite series, spectral response varies by instrument, sometimes dramatically. In fact, spectral response often varies by detector on the same instrument. Spectral responses are derived for all 12 channels of the SEVIRI instrument.
Note: SEVIRI PFM is onboard Meteosat-8, SEVIRI PFM2 is onboard Meteosat-9, SEVIRI FM3 is onboard MSG-3, and SEVIRI FM4 is onboard MSG-4.