DAVIS (Drill for Analogues and Visible Infrared Spectrometer) is the new laboratory model of Ma_MISS, which allows the optical system to be tested and operated with a replica of the drilling tool and in a real hole, representative of the actual holes that the rover will drill on the Martian surface. DAVIS consists of two main elements: (1) the Laboratory Drill (LD), a hand-held drill that mimics ExoMars’ capabilities, and (2) the measurement tool, the Ma_MISS Optical Tool (MOT), which mimics Ma_MISS’ optical characteristics. DAVIS, made by Leonardo S.p.A., will be used to test the operation of Ma_MISS on various samples, performing hyper-spectral imaging of the holes and reconstructing their stratigraphy and mineralogy.
This will allow the Ma_MISS team to evaluate the performance of the system and to develop, test and optimise observation strategies to be used on Mars during the ExoMars 2022 mission.
DAVIS-LD (the laboratory drill), is a drilling system that is operated manually, through a system of levers, to drill holes in rock samples, which are then analyzed with DAVIS-MOT.
The drilling tool is a replica of that in the flight model: drill is driven by the same electric motor but lacks the coring system and optical head. The drill is controlled by a commercial EC, which regulates the motor current to keep its rotational speed at the desired value. It is programmed to run the drill tool at the rated speed of 50 rpm.
The measuring instrument (DAVIS-MOT) exactly reproduces in terms of size and geometry the combined system consisting of the illumination system of Ma_MISS and the drilling system, and the optical capabilities of the Ma_MISS instrument in terms of the illumination system, light source, optical head, sapphire window, and signal fiber. It consists of a vertical rod 75 cm long and 25.4 mm in diameter, equal to the diameter of the drill.
The rod is manually activated by a knob, allowing it to pass through the drilled rock sample. The 5W VNIR light source is integrated into the top of the rod, and a 25-cm-long fiber-optic bundle channels light through the rod from the lamp to the optical head (illumination channel). Here where it is focused through the sapphire window outside the rod at the nominal focusing distance of about 0.6 mm. The reflected signal from the external target is then collected by the optical head itself (signal channel), after which an internal optical fiber sends the light back through the rod. A beamsplitter allows the light signal to be acquired by two separate Avantes VIS and NIR detectors through an FC/PC fiber optic connector used as an interface.