Mobile Penetrometer: “Mole” (96-97)
The Mobile Penetrometer or “Mole” is a mobility concept invented by VNIITransmash (Russia), a company based in St. Petersburg, experienced in lunar rovers – they contributed to Lunokhod’s instrumentation - and in soil sampling devices. (Gromov V. ET AL. 1997.)
The Mole carries an internal hammering mechanism, and is powered via a tethered cable: the repeated shocks drive it through the soil. It penetrates preferably loose and not consolidated soils, typically into regolith – also hard, e.g. permafrost. The Mole, whose original prototype was in the order of 1 m long, has been miniaturized and made space-worthy within an ESA-led development.
The ESA Mole has a size of 33 cm x diameter 2 cm and a mass of 0.4 kg; its small motor, 2 - 5 W max, provides 12 impacts/ min. The advance is typically 1 cm/min. in sand and 1 mm/min. in medium-hard regolith. Tests have demonstrated the mobility of the miniaturized Mole in ambient and TV conditions. Ground Tests have shown its capabilities of penetration in heaps of large pebbles. The depth capability is estimated to be 5 m. Retrieval by means of tether pull only would be limited to about 0.5 m depth, in loose soil. This prototype demonstrated the interest of the Mole as means of sub-soil penetration with low energy and power – a basis for further developments.
Last update: 26 January 2011