Effects of the RORSAT NaK Drops on the Long Term Evolution of the Space Debris Population

Recently the Haystack radar observations led to the detection of a previously unrecognized space debris family, with circular orbits between 600 and 1000 km of altitude and inclinations around 65 ffi . Due to their orbital and physical properties, such particles were tentatively identified by NASA as droplets of liquid sodium-potassium (NaK) coolant leaked from some of the nuclear powered radar ocean reconnaissance satellites launched by the former Soviet Union. In this paper we investigate the effects of the observed NaK droplets on the long term evolution of the debris population around the Earth. Moreover, the outcome of a possible future accidental loss of sealing in the secondary cooling loop of two specific satellites is analyzed as well. Because the NaK droplets are not able to induce catastrophic fragmentations of large targets, they do not alter significantly the future debris environment, as far as the possible onset of a collisional chain reaction is concerned.