Jefferson Manuel (Floorman, Siem Offshore) and Bonifacio Agonias (Assistant Driller, Siem Offshore) insert the magnetic susceptibility sonde (MSS) into the downhole logging tool string. The MSS is the bottommost tool that makes up the collection needed to record the condition and state of the borehole. Among the tools used in this particular tool string, called the triple combination (or “triple-combo”), are spectral gamma ray, resistivity, temperature, porosity, borehole diameter, and magnetic susceptibility. (Credit: Bill Crawford, IODP/TAMU) [Photo ID: exp351_053] Back to expedition photos.