“Operating spacecraft around comets: Evaluation of the near-nucleus environment”

We present a study of the current state knowledge concerning spacecraft operations and potential hazards while operating near comet nucleus. Starting from simple calculations comparing cometary coma environment to benign conditions on Earth, we progress sophisticated engineering models behavior, then confront these with recent proximity experience. Finally, make recommendations lessons learned for future missions that enter into orbit around long-term operations. All considerations indicate that, proper design planning, near-nucleus can be relatively safe region in which operate, even an active short period perihelion gas production rates as high 1e29 molecules/s. With densities similar those found good laboratory vacuums, dust Class 100 cleanrooms, particle velocities 10s m/s, microgravity forces permit slow deliberate operations, are generally more than typical day Mars. Even strong jets nucleus surface, tend only few grains/cm3, about same interior room Earth. Stochastic modern tens square meters projected surface area accounted using Attitude Control Systems within navigation error; contamination issues important spending months years kilometers surface; Rosetta faced, confusion celestial star trackers by sunlit particles flying past spacecraft, will addressed next generation implementing improved transient rejection algorithms.