# An Overview of CubeSat Missions and Applications
## 7 CubeSats as Deep-Space Exploration Platforms  
CubeSats have also obtained a notable and increasing role in the exploration of deep-space celestial bodies such as planets, planet-satellites, and asteroids, with a significant number of successful missions and an increasing number of planned, upcoming missions. What such CubeSat missions have in common, which is different than the vast majority of all other missions undertaken by CubeSats, is that the platforms undertaking deep-space exploration missions have to leave the Earth's orbit. This unique mission requirement means that deep-space exploration CubeSats differ in many aspects from traditional Earth-orbiting CubeSats, with the most significant differences being found on aspects such as radiation tolerance, telecommunications equipment, propulsion, and thermal design.  
More specifically, in terms of radiation tolerance, to get to their destinations, deep-space exploration CubeSats are most likely expected to travel through the Van Allen radiation belts, thus exposing their electronic equipment to the charged particles that are present in the belts. Furthermore, these CubeSats are expected to survive and operate  
Figure 17: (**a**) An illustration of the CubeSat BioSentinel. Illustration by NASA/Daniel Rutter [243]. (**b**) An example of the microfluidics cards carried by BioSentinel which contained the yeast sample to be studied. Photo by NASA/Dominic Hart [243].  
outside the protection of the Earth's magnetosphere, where they are constantly exposed to cosmic rays and solar energetic particle events. For these reasons, extensive radiation protection measures must be implemented for the success of these missions and the electronic components utilized have to be specifically designed and fabricated to mitigate the risks that stem from prolonged radiation exposure. When it comes to communications, telemetry, and tracking, deep-space exploration CubeSats have to overcome the extreme distance that separates them from the Earth, it is thus common for these satellites to be equipped with specifically designed, powerful communication systems and large antennas. Regarding propulsion systems, it must be noted that they can also be found on a considerable number of Earth-orbiting CubeSats, serving as a means to counter orbital decay and to perform orbital maneuvers. However, for interplanetary CubeSat missions, the existence of a propulsion system represents a necessity as it is required to generate the considerable amount of \(\Delta v\) that is required for interplanetary transfer maneuvers and/or orbital insertion in their destination celestial body. Finally, regarding thermal control systems, the high power of the subsystems commonly found on deep-space exploration CubeSats, as well as the extreme thermal environments these spacecrafts are expected to operate in, lead to the requirement for the design and implementation of robust thermal control measures [246].  
For this review, deep-space exploration CubeSats will be divided into three major categories based on the celestial body they are intended to explore, namely, lunar exploration CubeSats, planetary exploration CubeSats, and asteroid exploration CubeSats. Notable past, present, and upcoming CubeSat missions that fall within these categories are analyzed in more detail in the subsections that follow.