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Images: Engineer Par Excellence: Donald Koelsch

Don Koelsch prepares an instrument for deployment as part of the Low Frequency Acoustic Seismic Experiment. The instrument was designed to record seismic data for several months while stationed within a borehole drilled in the seafloor. (Photo courtesy of Josephine Koelsch)

Don Koelsch checks the electronics on the Near Ocean Bottom Explosives Launcher (NOBEL) on the research vessel Atlantis II in the 1990s. Koelsch helped develop NOBEL, which was the first system to successfully detonate multiple high-explosive charges at full ocean depths. Energy generated by the explosions could be detected by an array of seismometers, allowing geologists to glimpse the structure of Earth's crust beneath the seafloor. (Photo by James Broda, Woods Hole Oceanographic Institution)

Photoillustration of a seafloor hydrophone Don Koelsch helped design. The hydrophone detected and recorded sound waves generated by explosive charges set off near the seafloor. As the sound waves traveled through layers of sediment and crust, their strength and direction were affected by the structure of the layers they passed through.  (Photo illustration courtesy of G. Michael Purdy, Columbia University)

Don Koelsch (left) and other WHOI engineers and seismologists with the Near Ocean Bottom Explosives Launcher (NOBEL) system on the fantail of research vessel Atlantis II in 1991. On this cruise, they deployed the NOBEL system along the East Pacific Rise to gain understanding of how new crust forms on the seafloor. Also pictured (l to r, from Koelsch): MIT graduate student John Olson, WHOI research assistant Rob Handy, University of Hawaii scientist Gerard Fryer, and WHOI research associates Jim Broda and Beecher Wooding. (Photo by Dave DuBois, Woods Hole Oceanographic Institution)