H&S built COSIMA spectrometer for ESA's third cornerstone mission Rosetta for Comet 67P/Churyumov-Gerasimenko. COSIMA is a so-called SIMS instrument, a Secondary Ion Mass Spectrometer. It consists of a target manipulator with a robotic arm to collect and handle the substrates on which the cometary dust will be gathered, a small camera to locate the dust grains on the targets, a primary ion source to charge the dust particles, and a complete high-resolution time-of-flight spectrometer for negative and positive ion detection to measure the composition of the dust. More than 15 different high-precision high-voltage converters are necessary to control the flight path of the ions, which must be determined to a nanosecond accuracy.