# An Overview of CubeSat Missions and Applications
## 6 CubeSats as Platforms for Chemical and Biological Experimentation in Space  
To better understand the fundamental processes of life, CubeSats have served as platforms for conducting space-borne biological and chemical experiments. The harsh environmental conditions of these experiments play a significant role in giving more in-depth details of these processes as well as for addressing the challenges of long-term human space exploration. The microgravity, the vacuum of space, the intense radiation; all these unique conditions synthesize a \"laboratory\" like no one else on Earth. The risks of space travel on human health should be meticulously examined, risks such as bone density loss, muscle atrophy, and also DNA damage and immune system suppression. These insights will serve as a backbone for the countermeasures to protect humans on long-term missions, to the Moon, Mars, and beyond. Furthermore, other experiments studying animals, plants, and microorganisms play a vital role in future life support systems, especially if we consider the in-space life of astronauts an even potential human settlements apart from Earth. It is worth mentioning that the ISS has been utilized as a platform for conducting biological and pharmaceutical studies by various companies, such as the German company Yuri (Meckenbeuren, Germany) [230], but in this section we are going to focus only on dedicated CubeSat platforms. Beyond biology, studies involving chemical processes and reactions in space can further deepen our understanding of these phenomena, providing essential knowledge for applications in space and on Earth. A significant milestone in space exploration was the pioneering mission GeneSat-1 (see Figure 15a), a collaboration between NASA Ames Research Center, Stanford University, and Santa Clara University [231]. Launched in December 2006 aboard a Minotaur launch vehicle, this 3U CubeSat was the first free-flying CubeSat in LEO, with a dedicated biological mission. The payload module of this CubeSat contained an integrated fluidics system and high-precision optical sensors, capable of detecting and measuring a protein expression in Escherichia coli bacteria, namely the green fluorescent protein (GFP). This investigation on how metabolic processes and gene expression are affected by microgravity was the primary objective of this mission and it was achieved during the first week of operation. After the successful automated initiation of the experiment, the bacterial specimens were sustained by nutrient-rich growth medium in a temperature-controlled environment. In a span of only 96 h, the bacterial growth was tracked through optical density measurements and monitor the expression of the protein, using fluorescence detection. The GeneSat-1 mission not only demonstrated the feasibility of biological experiments in CubeSat missions but also paved the way for future missions to explore the biological effects of spaceflights. Following the successful GeneSat-1 mission, NASA Ames Research Center in collaboration with Santa Clara University and the University of Texas Medical Branch continued with the development of the PharmaSat mission [232]. Based on the same CubeSat design, this mission aimed to investigate the in-space resistance of yeast to antifungal agents, providing insight about the drug efficacy in microgravity. PharmaSat was launched in May 2009 and its payload included a self-contained miniature lab with 48 fluidic microwells, microfluidics systems, and optical sensors. For the yeast samples, they were prepared six weeks before launch using Saccharomyces cerevisiae, and they were reactivated in orbit three days after launch. Alongside the growth medium, four concentration levels of the antifungal agent voriconazole were provided to the samples in order to track the yeast population growth and its viability. The produced data for the yeast growth and antifungal response were telemetered to Earth, providing key insights about the drug resistance mechanisms and the behavior of biological systems in space.