On measuring the size of nuclei of comets
  Possibilities of measuring the size of nuclei of comets hidden by dust clouds are discussed. To this end, the dust cloud should be irradiated with a flow of rods accelerated in a linear mass accelerator to the velocity six kilometers per second. Each rod should be equipped with a transmitter with a power of one microwatt, which is destroyed in a collision with a comet's nucleus, or continues to work if the rod passes through the dust cloud without collision. Radio signals are received by three independent ground stations. At a distance of one thousand kilometers from the nucleus of the comet the power of the received signals is ten to the minus seventeenth Watt power, the receiver noise power is ten to the minus twentieth Watt power. 
S. N. Dolya
astro-ph.IM