SLSTR

SLSTR is a high accuracy infrared radiometer which will be embarked in the Earth low-orbit ESA Sentinel 3 mission as a part of the GMES (Global Monitoring for Environment & Security) operational program.

SLSTR is an improved version of previous AATSR and ATSR2 instruments, flying respectively on board of ENVISAT and ERS2, regarding higher swaths for Sea (SST) and Land (LST) Surface Temperature climatological and meteorological applications, a higher spatial resolution and two more solar channels for a better clouds/aerosols screening, and two additional channels for global scale fire monitoring (11 overall spectral channels). The program is in the phase B2/C/D and the first launch is scheduled for 2012.

The SLSTR Optical Scanning Unit comprises two scanners & telescopes which permit a quasisimultaneous observations of the same target with two atmospheric paths for correction of aerosols effects.

For each telescope, the IR and VIS energy is reflected off a Scan Mirror and focused by means of a paraboloid into a common Focal Plane Assembly (FPA). A flip mirror is used to alternatively switch from one view to the other.

FPA is a cylinder box composed of a base-plate, with an input field stop common for both views, dichroics for spectral channels separation and lens optics to focalize the beam onto each detector unit.

The IR/SWIR detectors and optics are cooled at 80K by means of a high space heritage & life time cryocooler, while the VIS ones operate at 260K.

The instrument cooling is assured by six separate passive radiators. A good radiometric calibration is achieved by observing with both telescopes every scan two accurate and stable blackbodies and every orbit a visible calibration unit with a sun diffuser.