# Fault Diagnosis and Prognosis of Satellites and Unmanned Aerial Vehicles: A Review
## 3 Review Methodology  
In this review paper, a systematic search and screening procedure (depicted by Figure 6) for relevant works in the field was carried out. First, an initial database of all the work that is reliable and relevant to the authors' knowledge pertaining to satellite, spacecraft, and UAV condition monitoring published by relatively reputable sources was curated. In this step, the main keywords and features of the gathered works were extracted. Then, a subsequent search procedure for relevant works was carried out with the most prominent scholarly search engines by using the main keywords. Even so, there is always the possibility of human oversight in this type of search process. Therefore, after conducting a comprehensive exploration using academic search engines, we studied the works cited by the already identified works and added the relevant citations to our database or pool of accumulated studies. The same process was repeated until all the relevant citations in every work in our database were examined. Furthermore, having a reputable publisher was an important screening criterion while gathering our database of studies. By reputable sources, we do not necessarily mean a journal that has a high impact factor or a high-ranking conference. Especially in the field of satellite FDP, with the limited work that has been published in this field, it might prove fallacious to consider a study publisher's ranking as the definitive deciding factor. Therefore, there were more nuanced approaches involved in judging a source's credibility. The challenge in this step arose from the lesser known sources. The papers published by the distinguished sources in the field were automatically entered into the next screening step, which is step #3 in Figure 6. The credibility of the other sources was gauged through an examination of the works published by them. If the publications of a source displayed glaring issues and mishaps, that source and its corresponding studies in our pool were disqualified. If the source exhibited patterns of bulk research papers with minimal contribution to their field, which was assessed by inspecting their content, year-of-publication, and number of citations, they were disqualified. The other factor that caused disqualifications was works that built upon prior methodologies but with insignificant and superficial additions and innovations. Figure 6: The review’s systematic search, screening, and analysis approach. Through the reviewing process, for the sake of brevity, the works that were determined to be continuations of each other were discarded, except for the latest variation of the research conducted in them, while conserving the main takeaways of each series of papers. This does not imply that the studies that shaped the current state of the literature of the field were not suitable but that they were so developed throughout different researchers' work that repeating them did not add much value to this review. Furthermore, in this review, emphasis was placed on promising works with high potential for improvement or real-life implementation. Therefore, as long as an article was scientifically sound, sophisticated, and with promising potential, they were included in the review regardless of its publication date. However, since the latest iterations of ongoing research movements were included in this review, many of the works are quite recent. The reviewing procedure is illustrated in Figure 6 for more clarity. By this step in the reviewing process, a pool of promising works had been compiled. The initial works contained about 130 works, of which 85 were selected for analysis in this review through the screening process. After this stage, a comprehensive content analysis was carried out, and the results are provided in Sections 4 and 5.