From https://www.globalsecurity.org/space/library/report/1993/noss_andronov.htm https://www.globalsecurity.org/space/library/report/1993/nos... > The last desi

From https://www.globalsecurity.org/space/library/report/1993/noss_andronov.htm https://www.globalsecurity.org/space/library/report/1993/nos... > The last designation more precisely reflects the mission and operating principle of the system's satellites. The mythological Parcae were the three daughters of Zeus and the goddess Themida (the SSU satellites are launched in groups of three and fly relatively close together.) One of the daughters spins the thread of fate for each mortal (one satellite has a wide observation swath, but cannot exactly determine the coordinates of radio emitters). The second daughter measures out a length of thread for each person (when two satellites get a fix on the shipborne emitters, the position is obtained, but with some ambiguity). The third sister (Atropos - "she from whom one may not flee") cuts the measured thread of life (the third satellite, getting a fix on the emitters' signals, enables their coordinates to be determined precisely and then transmitted to Navy ships for weapons employment. The naming, and its exposition by this Russian expert who was researching them, is oddly beautiful.