# An Overview of CubeSat Missions and Applications
## 9 Review Conclusions and Discussion
### CubeSat Platform Limitations and Intrinsic Challenges  
The present study primarily highlighted the diverse mission and application fields CubeSat platforms can be employed in, along with some of the main reasons that have led to the widespread adoption of these spacecraft by space science and engineering entities such as commercial companies, space agencies, and educational institutions. However, during the review of all these examples of missions some cross-cutting challenges and limitations that affect the vast majority of CubeSat designs have also become apparent. Addressing these challenges through future research and subsequent technological breakthroughs would lead to even wider horizons for future CubeSat missions. Perhaps the most significant limitation of CubeSat platforms was found to be their significantly constrained electrical power generation and storage capacity. This limitation can be attributed to the small area that is available for the installation of solar arrays on the exterior of these satellites and the limited volume available for the integration of energy storage cells. This bottleneck practically affects all CubeSat employment domains as it forces trade-offs between payload performance and mission lifetime. For example, capabilities of platforms used in the field of telecommunications are heavily impacted as transmission power is limited, while other types of CubeSats such as remote sensing and scientific ones are also affected as the mission-specific data-transmission rates they can achieve are also limited. Furthermore, remote sensing CubeSats are also affected by limited electrical power into mainly utilizing passive sensors such as imagers, spectrometers, and radiometers instead of LIDARs and active radar sensors which have, so far, not seen widespread adoption by the CubeSat industry. Such limitations could be mitigated to a degree in the following years through progressive advancements in the fields of electrical power engineering such as the introduction of higher energy density batteries and higher efficiency solar cells. It must be noted that system miniaturization, which has enabled the accommodation of complex instruments and payloads by CubeSat platforms, also features notable drawbacks as it also encompasses certain trade-offs and cannot continue endlessly. This is mainly because the performance of certain systems is governed by physical limitations. For example, in the case of optical imaging instruments, image resolution is proportional to the optical aperture size [335]; therefore, smaller optical instruments will always yield a reduced performance compared to larger, same technology ones. Miniaturization adversely affects the performance of other remote sensing instruments such as spectrometers also [336]. In a similar manner, in the field of telecommunications, smaller antennas will feature a reduced gain and signal-to-noise ratio compared to larger ones [337]. Apart from the miniaturization of systems, the miniaturized nature of CubeSat platforms also introduces certain other physical and engineering challenges. For example, the high density of electronic components packed inside the satellite, coupled with the limited volume and area available for the implementation of thermal control measures, entails a high risk of overheating. Furthermore, from a systems engineering perspective, the small size of CubeSat platforms rarely allows for the inclusion of redundant systems, especially in the case of small and low-cost designs, something that introduces single-points-of-failure to the overall design of the satellite, jeopardizing long-term missions. Other limitations of CubeSat platforms can also be pinpointed in the fields of attitude and orbit determination and control. Firstly, small CubeSats such as 1U and 2U ones, due to their compact size, often lack the means for precise attitude determination and control, thus limiting them to applications that do not require precise pointing capabilities of the satellite platform.