# An Overview of CubeSat Missions and Applications
###### Abstract
These dispensers may carry one or more CubeSats simultaneously and, after orbital insertion, eject the satellites through spring mechanisms, deploying them into orbit. When deployed from rockets, CubeSats may serve as secondary payloads to the rocket launch's primary payload or may be part of rideshare missions designed to place numerous CubeSats and other small satellites into specific orbits. Figure 2a illustrates the integration of CubeSat dispensers on the Evolved Expendable Launch Vehicle Secondary Payload Adapter (ESPA) of United Launch Alliance's (Denver, CO, USA) (ULA) Atlas V 401 launch vehicle. These CubeSat dispensers were used for the deployment of four CubeSats launched as secondary payload to National Aeronautics and Space Administration's (NASA) Landsat 9 Earth observation satellite [4]. Another common method of placing CubeSats into Earth orbit involves first transporting them to the International Space Station (ISS) as cargo during International Space Station (ISS) resupply missions. The CubeSats are then loaded into the Nanoracks CubeSat Deployer (NRCSD) or the JEM Small Satellite Orbital Deployer (J-SSOD) of the ISS's Japanese Experiment Module (JEM) by the station crew and subsequently deployed into the same orbit as the ISS [5,6]. Figure 2b shows the moment of deployment of the University of Patras Satellite (UPSat) CubeSat from the NRCSD of the ISS. Similar to their larger counterparts, the equipment carried by CubeSats can be classified into two distinct categories: the satellite bus and the satellite payload. The term bus \begin{table}
\begin{tabular}{c c c} \hline \hline
**CubeSat Size** & **Maximum Dimensions (cm)** & **Maximum Weight (kg)** \\ \hline
1U & 10 \(\times\) 10 \(\times\) 11.35 & 2 \\
1.5U & 10 \(\times\) 10 \(\times\) 17.15 & 3 \\
2U & 10 \(\times\) 10 \(\times\) 22.90 & 4 \\
3U & 10 \(\times\) 10 \(\times\) 34.05 & 6 \\
6U & 22.63 \(\times\) 10 \(\times\) 34.05 & 12 \\
6U XL & 22.63 \(\times\) 10 \(\times\) 36.60 & 12 \\
8U & 22.63 \(\times\) 10 \(\times\) 45.40 & 16 \\
12U & 22.63 \(\times\) 22.63 \(\times\) 34.05 & 24 \\
16U & 22.63 \(\times\) 22.63 \(\times\) 45.40 & 32 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Typical maximum allowable rail dimensions and weight of CubeSats based on their size. Figure 2: **(a)** The integration of CubeSats to the Evolved Expendable Launch Vehicle Secondary Payload Adapter (ESPA) of United Launch Alliance’s (ULA) Atlas V launch vehicle as secondary payloads to National Aeronautics and Space Administration’s (NASA) Landsat-9 Earth observation satellite. Photo by NASA/Jerry Nagy [7]. **(b)** The 2U University of Patras Satellite (UPSat) CubeSat during its deployment from the International Space Station (ISS). “Cropped version of the original image. Credit: Libre Space Foundation. Copyright (2023), Creative Commons CC BY 4.0 license” [8]. refers to all the subsystems responsible for sustaining and supporting the satellite during its mission. Such subsystems include the satellite Structure (STRU), the communications subsystem (COMM), the attitude and orbit control subsystem (AOCS), the electrical power subsystem (EPS), the onboard data handling subsystem (OBDH), the telemetry, tracking, and command system (TT&C), and the thermal control subsystem (TCS). The term payload refers to the equipment that provides the mission capability or service that the satellite is intended for. For example, the payload of an Earth observation satellite could be an optical imaging sensor, whereas the payload of a communications satellite would consist of all the antennas, amplifiers, transceivers, and transponders that enable communication with the ground segment of the overall system [9]. As a typical example of a CubeSat subsystem layout, Figure 3 presents the subsystem diagram of the University of Patras Satellite (UPSat), a 2U CubeSat jointly developed by the University of Patras and Libre Space Foundation (Athens, Greece) for the study of the lower thermosphere as part of the QB50 mission.