DSMC Computations of the Progress-M Spacecraft Retrofiring Exhaust Plume. AIAA Aerospace Sciences Meeting (37th) and Exhibit Held in Reno, NV on January 11-14, 1999

摘要

A set of DSMC computations using the SOCRATES computer code has been performed to aid in the development and analysis of the MirEx experiment to observe UV radiation from spacecraft thruster plumes. The plumes of interest for this report originate from the amine propellant main engine of the Progress-M and Soyuz-TM spacecraft. The altitude of the plume observations is approximately 380 km. The SOCRATES calculations provide a baseline estimate of the spatial distribution of the exhaust gases as they interact with the ambient low-density atmosphere composed predominantly of atomic oxygen. In addition, a proposed mechanism for OH(A) excitation based upon high-velocity collisions between H2O and O is exercised. A sequence of calculations was performed to investigate the influence of the angle of attack of the engine upon the predicted radiation levels. In general, it is found that the predicted OH(A) generation has a very large spatial scale, on the order of several kilometers. Comparison of the predictions with data showed the predictions were high, leading to speculation that the excitation cross section used in the calculations may be suspect. A preliminary variation of the energy threshold was performed using a set of experimental conditions. It was found that an increase in the energy threshold could bring the predictions into agreement with both the spatial distribution and the absolute signal level of the experimental data.