A procedure is developed and formulas are obtained for processing and analyzing output signals of neutral particle detectors (pressure probe) and current-voltage characteristics of a single cylindrical Lang muir probe, when high speed nonequilibrium rarefied plasma flows are diagnosed on board a spacecraft in the ionosphere and on a test bench. The results are supported by experimental data. The procedure is intended to evaluate values of a set of basic kinetic parameters of neutral and charged particles of partially ion ized rarefied gas flows.