# Advances in Remote Sensing and Propulsion Systems for Earth Observation Nanosatellites
## 1 Introduction
[10] explore the evolving landscape of space exploration, highlighting the increasing attractiveness of the space environment for various entities. They emphasize a significant shift since the second half of the 20 th century when substantial funds were required to build satellites and gain access to space. In contrast, contemporary technological advancements have produced small, robust hardware components capable of withstanding the harsh conditions of outer space. This technological progress has paved the way for the design of small satellites, mainly focusing on CubeSats, which are discussed comprehensively in the article. The authors delve into various aspects of CubeSats, including mission goals, hardware subsystems, components, network topologies, channel models, and communication protocols. They highlight the advantages of CubeSats, such as reduced design times, production costs, and deployment costs. Furthermore, the article provides insights into future challenges associated with deploying CubeSat networks, offering a comprehensive overview of the current state and potential future developments in small satellite technology. [PERSON] and [PERSON] [11] assess the evolution of CubeSats from educational tools to standard platforms for technology demonstration and scientific instrumentation within a short timeframe. They highlight the use of Commercial-Off-The-Shelf (COTS) components and ongoing miniaturization as critical factors contributing to the promising scientific value of CubeSat missions. The paper explores the advantages of CubeSats, including lower development costs, shorter development times, and the potential for launching multiple CubeSats with a single rocket launch. The authors propose the concept of large constellations or clusters of CubeSats as a novel mission architecture, breaking the traditional trade-off between temporal and spatial resolution in EO mission design. The survey thoroughly reviews CubeSat bus technology capabilities, identifies potential limitations, and assesses their implications on 17 EO payload technologies. Table 2 compares present work and existing surveys of nanosatellites and their applications. The paper provides a comprehensive analysis of the current state of nanosatellites, with a particular focus on Earth Observation (EO) missions and propulsion systems. It also includes a detailed examination of specialized applications, limitations, and directions for future research. The key contributions of this work are as follows:  
* A review of the most recent publicly known nanosatellite missions in EO. * An analysis of specialized applications of nanosatellites, particularly in EO. * A detailed taxonomy of nanosatellite propulsion systems. * A discussion of the key limitations of current nanosatellite technologies and proposals for overcoming these challenges. This paper first explores nanosatellite EO missions and propulsion systems and then discusses future research directions. In contrast to existing reviews, this paper does not solely focus on presenting surveys of applications or individual missions. Instead, it provides a holistic view, integrating insights on mission design, specialized uses, propulsion technology, and the major technological hurdles that must be addressed for the future development of nanosatellites. This paper is structured as follows: Section 2 describes the methodology. Section 3 reviews nanosatellites' EO applications in vegetation, natural disasters, inland water monitoring, oceanography monitoring, and specialized applications. Section 4 discusses nanosatellite propulsion systems, and Section 5 highlights challenges and future directions in nanosatellite technology.