Canadian Aeronautics and Space Institute (CASI) Alouette Award Winner: Spacecraft Reverberant Acoustic Chamber Facility Team, National Research Council

CASI created the Alouette Award to recognize an outstanding contribution to advancement in Canadian space technology, application, science, or engineering. This year the winners were the Spacecraft Reverberant Acoustic Chamber Facility Team, NRC.

Random vibration of spacecraft which is induced by acoustic emissions from the launch vehicle at lift‐off is a prime structural design driver. In order to qualify the design for launch, the spacecraft is subjected to acoustic environment loading to simulate the launch condition which is generally of the order of 140 dB or higher inside a payload fairing. This acoustic environment is most commonly generated in an acoustic reverberant chamber designed to simulate the noise environment of launch which is random in nature. However, since this noise environment is difficult to generate accurately, large tolerances on octave band component amplitude are generally allowed. As a result, the spacecraft must be designed to have higher structural safety margins than might be necessary to accommodate this wide tolerance, which increases the launch mass and complexity of the spacecraft to sustain the environment.

The National Research Council’s (NRC) Aerospace Research Centre maintains and operates a large (26 x 23 x 32 ft) high‐intensity reverberant acoustic chamber test facility for the development, qualification, and acceptance testing of full‐scale spacecraft hardware. This is the only acoustic chamber facility in Canada capable of testing full-scale space structures in an intense noise environment representative of that found within a rocket fairing during the launch. Most spacecraft and components manufactured by the Canadian space industry for commercial and government needs are tested at the NRC acoustic chamber facility, which has been in operation since 1982 and provides a crucial Assembly, Integration, and Test capability to complement other test facilities at the David Florida Laboratory operated by the Canadian Space Agency.

As mentioned above, it is difficult to accurately simulate the random noise environment which can also be influenced in a non‐linear manner by the damping of the test article. Furthermore, the noise generators also are fundamentally nonlinear with respect to their input‐output characteristics. Initial testing was done using manual adjustment and scaling factors on the noise environment which was not only difficult but required large tolerances to achieve the required acoustic environment. To overcome this difficulty, a hardware‐ and software‐based real‐time Acoustic Spectrum Control System (ASCS) was designed and implemented in the early 1990s which greatly improved the capability. But after 25+ years of service, the ASCS hardware had become obsolete.

The NRSC’s Spacecraft Reverberant Acoustic Chamber Facility Team, consisting of the nominees, addressed the challenge by developing a newer generation of Acoustic Spectrum Control System (ASCS) in-house to enhance the capability of the NRC large spacecraft reverberant chamber facility. Compared with other commercial ASCS software, the NRC proprietary software enabled quicker convergence and higher accuracy of the acoustic field in the chamber, which minimizes the unnecessary exposure of high levels of acoustic loading of the spacecraft during test set‐up. In addition, it also introduced new safety features such as the automatic elimination of faulty control microphones and energy limits on critical control bands.

This new ASCS system enables efficient operation of the facility by automating sensor calibration and automatically generating required reports at the end of the test sequence, allowing for a quick turnaround for tests to meet strict schedules in the space industry. Since its commissioning in 2015, the new ASCS has advanced Canadian AIT capability, successfully completing more than 50 acoustic qualification tests for clients.

The enhanced control accuracy and safety of the new ACSC of the NRC Spacecraft Reverberant Acoustic Chamber Facility enables Canadian spacecraft manufacturers to design more optimal spacecraft structures to meet launch environment specifications and to offer superior spacecraft designs for Canadian and international space programs.

Since its commissioning, successful acoustic qualification tests have been completed on three RADARSAT Constellation Mission (RCM) spacecraft and many large satellite antennae and reflector assemblies for clients. The new system is able to achieve the tightest tolerance among the major facilities worldwide, enabling customers to design lighter structures while meeting or exceeding other tight specifications demanded by their users within the global spacecraft market. Furthermore, these new enhancements have also contributed to the success of their space projects by reducing the turnaround time for tests and providing flexibility to accommodate changes in schedule due to unforeseen technical challenges. The NRC’s Spacecraft Reverberant Acoustic Chamber Facility has proven to be a critical advantage for Canadian companies to maintain their lead in the space industry and continue to provide superior products in order to win competitions for international space programs.