CaSSIS (Colour and Stereo Surface Imaging System)

ODE: Mars

Mission: ESA's ExoMars Trace Gas Orbiter

Instrument:CaSSIS

Instrument Team Site: CaSSIS Team Web Site

PDS4 Bundle: urn:esa:psa:em16_tgo_cas

Search ExoMars Trace Gas Orbiter CaSSIS data in Mars ODE: Product Search

Colour and Stereo Surface Imaging System (CaSSIS) was developed by the University of Bern. CaSSIS takes high resolution stereo images in 4 colours of the Martian surface. This imager characterizes sites which have been identified as potential sources of trace gases and investigates dynamic surface processes and certify potential future landing sites. CaSSIS observes a 9 km wide swath thereby providing the best colour imaging acquired from Mars, so far.

CaSSIS comprises two major units: Camera Rotation Unit (CRU) and Electronics Unit (ELU). The CRU comprises the telescope (incl. focal plane and associated electronics), the rotation system, cable management system and some structure to support all of the above and mount the CRU to the spacecraft. The ELU contains the boards with the electronics required to operate the camera.

CaSSIS is based around an 875 mm focal length carbon-fibre reinforced polymer (CFRP) telescope with a 135 mm primary mirror and a 2k x 2k CMOS hybrid detector with 10 micron pixel pitch providing 4.6 m/px imaging from the nominal 400 km circular orbit. The telescope is a slightly modified three mirror anastigmat optical configuration with no central obscuration. The instrument is designed to operate in “push-frame” mode where 2048 x 256 images are acquired at a repetition rate which matches the ground-track velocity (~3 km/s) allowing sufficient overlap for co-registration thereby building image strips along the surface.

TGO CaSSIS Products have been archived in PDS4 standard. They are grouped into PDS4 collections based on processing level.

PDS4 Collection	Bern Products equivalent	Description	PDS4 Bundle
Raw Data	Level0	The ExoMars TGO CaSSIS raw product collection consists of raw science data, housekeeping telemetry and telecommand telemetry.	urn:esa:psa:em16_tgo_cas:data_raw
Partially_Processed Data	Level1a, level1	The ExoMars TGO CaSSIS partially processed product collection consists of raw science data that has some, but not complete set of calibrations applied.	urn:esa:psa:em16_tgo_cas:data_partially_processed
Calibrated Data	Level1c, stitched	The ExoMars TGO CaSSIS calibrated product collection includes science data where all calibrations have been applied. Level1c data refers to calibrated framelets, whereas stitched refers to level1c framelets that have been stitched together.	urn:esa:psa:em16_tgo_cas:data_calibrated
Derived Data		N/A	N/A

Thomas, N., et al. (2017), The colour and stereo surface imaging system (CaSSIS) for theExoMars Trace Gas orbiter. Space Sci. Rev. 1-48. https://doi.org/10.1007/s11214-017-0421-1