SSA/DT (95-97)

To prepare the Agency for the perspective of less ambitious planetary missions, the development of a basic surface sampling tool, as simple as possible, quasi-minimalist, was undertaken within the TRP. An alternative would be available to analyze a soil sample in-situ, instead of back on Earth (as in the CNSR scenario), (Re E. ET AL. 1997). [ http://adsabs.harvard.edu/full/1997ESASP.410..271R ]

The developed tool, the Small Sample Acquisition and Distribution Tool (SSA/DT), had to be capable of sampling over a large range of surfaces, but to acquire only a few soil grains (a few cubic mm). The SSA/DT was small and compact: its essential requirements were a mass of 1.5 kg, a volume of 5 dm3 stowed; its outreach was a radius comprised between 100 and 150 mm; it used only a few watts of power.

SSA/DT on its test stand

The acquired sample was delivered to the analyzer oven within its tool bit as container. Sample and tool were left in the oven during sample heating and analysis. The SSA/DT could carry several tool bits, stored in a tool rack, which could be exchanged.

A SSA/DT prototype has been tested in TV conditions, from -160 0C to +140 0C, representing the extreme temperatures foreseen from comets to Mars, including the Moon. Mission application to this promising development remains to be found. The study team gathered Tecnospazio with Tecnomare, SSS (I) and VTT (SF).

SSA/DT tools and Micro End-Effector (MEE)

SSA/DT Tools

The SSA/DT tools were purposely kept rugged and simple, made in one piece: they had to survive the oven temperature. They could be described by their nicknames: the “inverted cheese-scraper” and the “wire cage sampler”.

In contrast to the basic SSA/DT tools, the Micro End-Effector (MEE) tool [http://www.hkmars.net/] was quite complex, but also extremely innovative. Its inventor, Dr. T.C. Ng with a team of the Hong-Kong Polytechnic University, had previously presented their research to ESA: it was related to large sampling tools, like planetary rock-pickers. This team undertook the challenge of miniaturizing their concepts, made of articulated parts and screw joints.

The MEE tool is articulated like pliers, which may rotate along their main axis around a threaded support; when pushed on a soil surface and rotated, the friction torque, transmitted via a linkage, allows opening or closing them.

One MEE tool was kindly delivered to ESA free of charge. A number of prototypes were later built, tested on soils at ambient, and further improved.

The MEE has shown that, in principle, complex miniature tools may be designed. To survive the oven environment, a number of details in the tribology of the joints should be designed in detail, in particular the materials and lubricants.

Last update: 7 May 2014

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