Sample Preparation and Distribution System (SPDS)
The Sample Preparation and Distribution System (SPDS) is the assembly of structures, mechanisms, containers and devices that allows the transport and the processing of the samples collected by the ExoMars drill. It is on this sample material that the scientific analysis will be performed.
The SPDS is intimately linked with the analytical laboratory instruments, their electronics and with their means of thermal control. It is located in the Payload Module, in the front part of the Rover.
The Rover AIV (assembly, integration and verification) approach foresees the integration of the SPDS elements and of the scientific instruments in a single drawer (Analytical Laboratory Drawer – ALD) that, enclosed in a special bio-barrier bag, will be inserted in the Rover body structure shortly before the final spacecraft integration.
The Pasteur analytical laboratory instruments are:
- MA_MISS spectrometer (the Mars Multispectral Imager for Subsurface Studies: a bore-hole IR spectrometer, in the drill tool)
- MicrOmega (an infrared imaging spectrometer)
- RLS (a Raman spectrometer)
- MOMA (Mars Organic Molecule Analyser – a combined laser desorption / gas chromatograph mass spectrometer)
The sample collected by the drill (a core of roughly 3 cm length by 1 cm diameter, or a collection of fragments and powder is passed to the Rover and dropped into the crushing station. The crushing station is used to produce a powder with the desired particle size distribution. This powder is further distributed by a dosing mechanism, either to:
- A refillable container, serving MicrOmega IR, RLS, and MOMA-LDMS (laser desorption mass spectrometer), which can be emptied and reused for new analyses.
- One of the several ovens hosted by the carousel. These ovens can be used one time only, and are needed for the MOMA-GCMS (Gas Chromatograph Mass Spectrometer) investigations.
The SPDS is designed to support also 'blank' measurements,in other words, to process organically inert mission samples to demonstrate the Rover’s cleanliness along the entire sample transportation and distribution chain. This is an important step to provide the necessary credibility to the search for biomarkers.
In summary, the ExoMars Rover SPDS includes the following elements:
- Sample receiving mechanism/container (interfacing with the drill unit)
- Sample transport system, from inlet port to crushing station
- Crushing station
- Dosing station (1 device)
- Sample distribution carousel, equipped with both re-usable sample container(s) and a finite number of ovens for gas chromatography
- Sample flattening device (to render particulate matter flat for observation by instruments)
- Blank sample dispenser