# An Overview of CubeSat Missions and Applications
## 8 The Use of CubeSats in Novel Technology Demonstration Missions
### Propulsion and Maneuvering Demonstration
This type of technology can play a significant role in the rising problem of space debris in the future. Some notable missions involving novel propulsion systems are NanoSail-D2, Light-Sail 2, and Pathfinder Technology Demonstrator-1 (PTD-1). Launched in November 2010, NanoSail D-2 was a 3U CubeSat developed by NASA's Marshall Space Flight Center and Ames Research Center, with the primary mission of demonstrating the deployment of a solar sail in LEO [299,300]. Given that the sail operated without active attitude control, it provided substantial insight regarding its stability, the impact of solar radiation pressure, and aerodynamic drag. The sail also tested and validated the Triangular Rollable and Collapsible (TRAC) booms that successfully achieved passive deployment of the sail in approximately five seconds. Following this mission and LightSail 1, in June 2019, LightSail 2 was launched aboard a SpaceX Falcon Heavy rocket, aiming for solar sailing demonstration [301]. Developed by The Planetary Society, this 3U CubeSat successfully deployed a 32 m\({}^{2}\) solar sail using TRAC booms. After the deployment and the resolving of some trivial deployment issues, LightSail 2 began its controlled sailing by orienting the sail to the Sun, effectively increasing its orbital energy, achieving measurable increase in its apogee while mitigating the orbital decay. This mission's success proved that solar sails can effectively harness the solar photons' pressure for sustainable propulsion. Another mission for sustainable propulsion was the Pathfinder Technology Demonstrator-1 (PTD-1) mission [302]. Launched in January 2021, this 6U CubeSat was a NASA initiative in collaboration with Tethers Unlimited, Inc. (Bothell, WA, USA) with the main objective of demonstrating, testing, and validating the HYDROS(r) propulsion system (Tethers Unlimited, Inc., Bothell, WA, USA) that used water electrolysis technology. After the electrolysis, hydrogen and oxygen gas were combusted in a bipropellant rocket nozzle, achieving a high specific  
Figure 22: Exo-brake deployment during the Technology Education Satellite-10 (TechEdSat-10) mission, photo from ISS. Image credit: NASA [298]. impulse in the range of 223-241 s, close to the ground control testing. The propulsion systems occupied a volume of 2U and was subjected to multiple thrust events. Although the first event was unsuccessful, the following firings produced a substantial orbit change, validating the thruster's ability to perform in space environment. The PTD-1's successful demonstration set a major milestone for water propulsion systems in space, validating the feasibility of non-toxic, refuelable, and high efficiency propulsion for the next generation of space missions. Another two interesting cases are the InflateSail and DeorbitSail missions, which were pioneering European CubeSat projects developed by the Surrey Space Centre (SSC) at the University of Surrey, aiming to demonstrate innovative drag sail technologies for satellite deorbiting. InflateSail, launched in June 2017 as part of the QB50 program for the Von Karman Institute (VKI), Belgium, was a 3U CubeSat that deployed a 1-m inflatable boom and a 10 m\({}^{2}\) drag sail, successfully re-entering the atmosphere just 72 days after launch. This marked Europe's first successful demonstration of inflatable deorbiting technology [303]. DeorbitSail, funded by the European Commission's FP7 program, also utilized a 3U CubeSat platform to test a larger 5 \(\times\) 5 m gossamer sail supported by CFRP booms, with a complex deployment mechanism that included a translation stage and deployable solar panels which doubled as structural restraints. Both missions tackled the challenges of compact storage, precise deployment, and power management, validating the feasibility of lightweight deorbit systems to address space debris mitigation in line with international guidelines [304].