Mir-based measurements of the ultraviolet emissions from rocket exhaust plume interactions with the atmosphere at 380-km altitude

A set of experiments has been performed to study the emissive species and the excitation mechanism of ultraviolet radiation observed during the operation of the chemical thrusters of the Progress-M and Soyuz-TM spacecraft. The radiation of interest to this study is the result of the interaction of the exhaust plumes with the ambient atmosphere. Typical altitudes of the spacecraft during the measurements range from 360 to 390 km. The general concept is to view the plumes of service spacecraft as they approach and leave the Mir station, using the Mir space station as a platform for a suite of optical instrumentation. Stellar sources were used to radiometrically calibrate the instrumentation in situ onboard the Mir station. The aftviewing data show that the plume radiation consists of a small bright region along the line of sight from the Mir to the spacecraft, and a large relatively dim cloud extending several kilometers around the spacecraft. The imager was operated with both a wide-band (266 nm to 316 nm FWHM) and narrowband filter (307 nm to 325 nm FWHM). The results showed that plume-atmosphere glow exhibits behavior similar to the preceding experiments. An examination of the ignition transient of the UV emission indicates that some relaxation processes in the flow field are involved in the radiation development. The spatial profiles of the radiation are presented and it is seen that profiles are narrower than predicted by current modeling efforts. Finally, the absolute values of the radiation derived from the experimental data agree with earlier measurements, but appeared to be more than an order of magnitude less than that predicted by theory.