Levels of Testing in the Software Development World: The Case of the Ariane Rockets and BioAffix

The Foundations of Combating Climate Change and First Steps for a Sustainable Future: The Ariane Rockets

In 1970, driven by a desire to overcome impossibilities, achieve independence in the space race, and dream of new goals, a group of engineers in Europe began developing a launch rocket to carry satellites and their apparatus for low-altitude and scientific missions into space. In June 1979, this effort bore its first mature fruit, and the Ariane 1 rocket carried the French research satellite CERISE (Cérès et l’Interférométrie à Résonance Infrarouge pour les Sondes Extérieures) into space. The satellite was designed to conduct studies on atmospheric research and space sciences. The data collected by CERISE provided important information about the distribution of aerosols and gases in the atmosphere. This data contributed to the development of climate change models and the understanding of atmospheric dynamics, and it still provides a reference for many climate change studies conducted today.

Aerosols are small particles in the atmosphere that can have significant effects on the climate. Aerosol gases can be released through volcanic eruptions, industrial emissions, and other natural or artificial sources, and by reflecting sunlight, they can reduce the amount of radiation reaching the Earth’s surface. The data recorded by the CERISE satellite on the distribution of aerosol gases helped scientists understand the effects of atmospheric particles on the climate system. This success was considered a major step in Europe’s space program and laid the groundwork for the development of future Ariane rockets.

By 1990, the Hubble Space Telescope, which would provide crucial observations for determining the formation of galaxies, dark energy, and the age of the universe, and revolutionize the field of astrophysics, had been sent into space by the American National Aeronautics and Space Administration (NASA).

Errors Encountered During Development Lead to the Best Version

By June 1996, the European development team’s work had also gained momentum, and the Ariane 5 rocket had been developed. The development journey that began in 1970 had continued with constant improvement over 26 years, resulting in 69 successful launches to date. The payload capacity of the Ariane 5 rocket, which would go down in project development and software history, was increased from 2,500 kilograms to 10,000 kilograms. With the developed Ariane launch vehicle, the European Space Agency (ESA) would carry the Herschel Space Observatory and the Planck satellite into orbit, ultimately collecting data to calculate the age of the universe and achieving an international success.

Ariane 5 was launched from the Kourou Space Centre in French Guiana. Initially, everything seemed to be going well. However, approximately 37 seconds later, a software error occurred in the systems required for the rocket to settle into orbit, and the rocket’s self-destruct mechanism was activated, destroying it. This event was recorded as one of the most expensive software failures in history.

Investigations showed that a data type error occurred during the launch. The launch system software for the Ariane 5 rocket was created with code inherited from the development of its predecessor, Ariane 4. However, Ariane 5 had more powerful engines and a higher payload capacity than the previous version. The rocket’s velocity data was processed in an integer format in the previous version. In Ariane 5, this needed to be converted to a larger and more precise format: floating-point numbers. During this conversion, the velocity data grew unexpectedly and exceeded the limits of a variable. The velocity data reaching a negative or very high value caused the system to crash. This “small” error cost $500,000,000 and extended the development process by another five years. Of course, besides the loss of the rocket and project delays, there were also broader impacts, such as a loss of reliability and reputation.

The outcome served as a significant example of an insufficient software testing process. The software tests, which were not completed in accordance with the requirements of the new rocket, failed to meet the system’s needs. Perhaps due to a lack of time or perhaps due to confidence in the code inherited from the previous system, the failure to perform unit and integration tests caused these 37 seconds to be remembered as one of the most expensive software failures in history.

In July 2024, with the successful launch of its latest generation, the Ariane 6 rocket, the European Space Agency (ESA) refreshed its presence in the rapidly changing commercial launch service market, backed by over 50 years of development experience. Furthermore, the contribution of this accumulated experience to the process was once again proven on a global scale.

Whether it’s a high-tech space launcher or a physical access control device, a testing process blended with manufacturing experience is a necessity for all systems, as demonstrated by the Ariane example. The same diligence is adopted in the development of the BioAffix ecosystem.

Testing Processes in BioAffix Access Control Systems

The BioAffix software, whose version 24.2 was recently released, is subjected to various tests during each software lifecycle period. In light of the information and findings obtained, all BioAffix teams work meticulously to ensure that the next software version is delivered to users with the minimum possible software errors. To prevent critical errors during version transitions, unit tests are applied to the smallest parts of the software (functions and methods). Unit tests are written, executed, and automated by software developers. The purpose of these tests is to improve the debugging process and code quality.

Inter-Module Compatibility with Integration Tests

After unit tests are applied to new features added to the BioAffix software, integration tests are conducted to verify that different components work together as they should. Integration tests are performed to check the interactions between modules. For example, BioAffix devices that communicate using the OSDP (Open Supervised Device Protocol) infrastructure can instantly report their status to the control panel they are connected to and receive direct commands from the main command panel.

Commands to be sent to peripheral devices can include functions like opening/closing outputs, sounding an alarm, or changing the colors of warning lights. After the sent commands are processed, the behavior of the devices should return to normal as defined in the system flow. In this case, while unit tests are applied to the commands and their infrastructure, the processing of these commands by the OSDP peripheral device, their return to the normal system flow, and their proper functioning are verified through integration tests.

Testing Reliability with System Tests

In every new software version, system tests are performed to check the software’s functionality, reliability, and performance. These tests, based on real user scenarios, are meticulously carried out by the BioAffix Hardware and Software Test team. Thanks to its high integration and compatibility capabilities, the BioAffix system can work in harmony with all commonly used existing systems. Based on this, the functionality of every single feature of the system is checked. Within system tests, usability tests are conducted to evaluate non-user-friendly functions of the software, and feedback is provided to stakeholders for improvements. After every bug fix and with each new feature added, regression testing is performed to re-verify that functions work correctly. System tests also include security testing. The software’s security vulnerabilities and data protection measures are tested. These testing steps are of great importance, especially for systems like BioAffix software and hardware that operate with high security needs and goals. The tests performed to prevent small or large critical errors, like the Ariane 5 rocket example mentioned at the beginning of this article, are organized through specific processes. These include test planning, preparation of test scenarios and cases, creation of test environments similar to real field environments, error reporting, correction, and evaluation of results.

Another testing step is the acceptance test. It is performed to verify that the software meets user requirements. Acceptance testing is conducted by real users. For the development of BioAffix software, change requests from users are collected and evaluated during the software development lifecycle. Accordingly, improvements and developments are made in the system, and new versions are prepared. Users evaluate how the software works in their daily business processes through acceptance tests. Acceptance testing also includes Operational Acceptance Testing (OAT). Operational acceptance tests cover the software’s operational scenarios, such as backup, recovery, and data migration. In BioAffix software, communication processes are encrypted and highly secure. All critical data is transferred to users’ databases in an encrypted manner and can only be viewed and edited by authorized users.