An analysis of the orbital distribution of solid rocket motor slag

Abstract

The contribution made by orbiting solid rocket motors (SRMs) to the orbital debris environment is both potentially significant and insufficiently studied. A combination of rocket motor design and the mechanisms of the combustion process can lead to the emission of sufficiently large and numerous by-products to warrant assessment of their contribution to the orbital debris environment. These particles are formed during SRM tail-off, or the termination of burn, by the rapid expansion, dissemination, and solidification of the molten Al 2 O 3 slag pool accumulated during the main burn phase of SRMs utilizing immersion-type nozzles.Though the usage of SRMs is low compared to the usage of liquid fueled motors, the propensity of SRMs to generate particles in the 100 μm and larger size regime has caused concern regarding their contributing to the debris environment. Particle sizes as large as 1 cm have been witnessed in ground tests conducted under vacuum conditions and comparable sizes have been estimated via ground-based telescopic and in-situ observations of sub-orbital SRM tail-off events.Using sub-orbital and post recovery observations, a simplistic number-size-velocity distribution of slag from on-orbit SRM firings was postulated. In this paper we have developed more elaborate distributions and emission scenarios and modeled the resultant orbital population and its time evolution by incorporating a historical database of SRM launches, propellant masses, and likely location and time of particulate deposition. From this analysis a more comprehensive understanding has been obtained of the role of SRM ejecta in the orbital debris environment, indicating that SRM slag is a significant component of the current and future population.

Space Debris: Optical Measurements

“…Since the 1960s micrometer (dust) to centimeter (slag) sized particles were created during the burning process of 𝑠𝑜𝑙𝑖𝑑 𝑟𝑜𝑐𝑘𝑒𝑡 𝑚𝑜𝑡𝑜𝑟 (SRM) in space. Such residues are mostly composed of aluminium oxide, mixed with SRM liner material [8]. All space objects, such as satellites, rocket bodies and fragments are exposed to the rough space environment.…”

Study of Particle Size Measurement by the Extinction Method in Flame

“…Some solid rocket motors work in outer space, where the large particles or debris produced by these SRMs are a kind of space debris, and these particles pose hazards to space transportation [16]. Large solid particles pose a threat to equipment that operates in space, where particles larger than 100 µm in diameter can penetrate astronauts' space suits and particles larger than 5 mm in diameter can penetrate the weak parts of the space station [17]. To date, there are relatively few internal and external flow field parameters that can be measured for SRMs.…”