The DFMI instrument was turned ON for the Annefrank asteroid encounter for about 28 minutes. A short calibration was performed immediately after the power was turned ON at 23 minutes before the closest approach and another shortly before the power was turned OFF at 5 minutes after closest approach. Figure 1 graphically shows the event counts as a function of DFMI internal time counter during the entire period that the DFMI instrument was ON. No dust event was registered in any of the 8 polyvinylidene fluoride (PVDF) counters during the entire period.

Figure 1

One of the 8 acoustic counters registered one burst at one particular time which we associate with some spacecraft activity. This is being investigated in coordination with the spacecraft navigators.

As far as we can say from the received data, the DFMI instrument performed exactly as expected and we had not seen any dust impacts during the entire period the instrument was operating.