# Agile Stage-Gate Approach for Design, Integration, and Testing of a 1U CubeSat
## 2 Materials and Methods
### Testing Development Process  
In the software industry, Agile testing is an integral part of product development because developers write integration tests after unit tests. In the development of physical products, the various testing activities are categorized as verification and validation processes. The testing development process is a feature and well-known identifier of Agile development. In this paper, we highlighted the contribution of validation testing in the Agile development of a nanosatellite within a gate. The satellite was tested using a thermal vacuum test and a vibration test. Acceptance tests are conducted to demonstrate the acceptability of an item for flight. Acceptance tests measure performance parameters and reveal inadequacies in manufacturing processes such as workmanship or material. Such tests also demonstrate acceptable performance over the specified range of mission requirements [27]. Due to the nature of the system, all validation tests were performed using a serial monitor assessment. Vibration test: This test is intended for spacecraft with low-to-moderate weight and size. For small payloads, the test should cover the full 20-2000 Hz frequency range for random vibrations [28]. If a random vibration test is appropriate, then the project should obtain the spacecraft's random vibration environment from the launch provider. Random vibrations require that the nanosatellite complies with random acceleration levels. Low-frequency transient vibrations occur during the launch, and random vibrations under 2000 Hz appear due to the environment. The requirements for power spectral density (PSD) are given in Table 3. The PSD is expressed in g\({}^{2}\) per Hertz. A random test is defined for each axis. The payload in its launch configuration is attached to a vibration fixture using a flight-type launch vehicle adapter (Nanoracks CubeSat Deployer) and attachment hardware. Vibrations are applied to the base of the adapter in each of the three orthogonal axes, one of which is parallel to the thrust axis. The main goal of this test in the spacecraft is to verify the craft's ability to survive the lift-off environment and to provide a final workmanship vibration test. For AztechSat-1, vibration testing used the SpaceX launch vehicle profiles. AztechSat-1 passed the test and survived the environment in the launch vehicle. Thermal vacuum test: According to NASA standards, an appropriate set of tests and analyses must be selected to demonstrate the spacecraft's capabilities by emulating a space environment using laboratory equipment. The spacecraft must perform satisfactorily within the vacuum and thermal mission limits defined by its final orbit. AztechSat-1 is intended for LEO, with expected temperatures from \(-20\) to \(60~{}^{\circ}\)C [27]. However, the AztechSat-1 thermal vacuum test was conducted in the range of \(-15\) to \(60~{}^{\circ}\)C due to the small size of the satellite [29]. During the test, the thermal design and thermal control system must maintain the affected hardware within the established thermal limits of the mission throughout the planned mission phases. The purpose of thermal vacuum testing is to detect defects in materials, processes, and workmanship by subjecting the unit under testing to thermal cycling in a vacuum environment. Both stabilized and transitional conditions were produced; these conditions induce stresses intended to uncover incipient problems. Thermal vacuum testing of the hardware should be conducted after dynamic testing is completed. This process helps to ensure that incipient failures induced by transient dynamic tests are discovered during later test phases. In our project, a thermal limit test was conducted to assess the battery, payload, and mission life. The test consisted of cycling the flight system in the thermal chamber at temperatures of \(-15\) to \(60\)\({}^{\circ}\)C.  
AztechSat-1 was placed in the vacuum chamber and decreased to a hard vacuum (a least \(3\times 10^{-4}\) Torr).