Satellite Test Operations – Human Spaceflight

Last month’s blog post dealt with Satellite Test Operations for GEO/LEO Satellites. Direct Field Acoustic Testing (DFAN) technology has evolved alongside the increased launch cadence ushered in by the “new space” movement. As such, the GEO/LEO market has been the primary driver in developing a scalable efficient acoustic testing system. However, Direct Field Acoustic Testing (DFAN) is also increasingly being used for human spaceflight applications. Manufacturers of the human spaceflight hardware have traditionally conducted Assembly, Integration and Testing (AIT) campaigns at locations that have reverberant chambers to perform acoustic testing. Reverberant acoustic testing has been used for decades and is generally well understood. Understandably, human spaceflight has always been risk averse, especially with embracing new test methodologies. Over the last decade, Direct Field Acoustic Testing  (DFAN) testing has been shown to be acceptable for human spaceflight while offering many unique benefits to traditional methods.

The test requirements for human spaceflight are much more substantial than for uncrewed missions. Specialists test each system and subsystem multiple times in different configurations as it is built up into a finished module. Then they test the backups to those systems. And test again. Human-rated systems are typically triple fault redundant. This includes Propulsion systems, Environmental Control and Life Support Systems (ECLSS), mechanisms and crew systems. The integrated module level tests are very important milestones in the build process with acoustics typically sequenced close to the end of the AIT flow. In many ways, it is one of the last “dress rehearsals” before the big opening night of launch. Since the end of the overall testing campaign is often in sight during Direct Field Acoustic Testing  (DFAN), these tests are some of the most closely scrutinized. The test requirements for a human spaceflight module typically will involve functional checks of all systems before and after the DFAN test campaign along with system health checks during test execution. Ground testing of these systems often requires extensive Mechanical Ground Support Equipment (MGSE) such as cooling carts. Also, special tooling and ground structures fulfill the role of strain relief for harness connections.

Planning is paramount for a human spaceflight Direct Field Acoustic Testing  (DFAN) test. The test configuration (both facility and test article) must be considered when developing a test procedure for a Direct Field Acoustic Testing  (DFAN) test. Per the “Test Like You Fly” doctrine, it is desirable to have the module as close to the launch configuration as possible.  This is often a balancing act as the time and cost required to put hardware into the flight configuration would be prohibitive. This leads to “test only” configurations that must be implemented leading up to or during the middle of Direct Field Acoustic Testing  (DFAN) test execution (placing an instrumented mannequin into the capsule and securing the hatch). By design, the ARS system offers the flexibility to adapt to each test configuration needed at that moment. ARS develops a specific test procedure for each test. This test procedure needs to be client- and peer-reviewed to capture the intricate choreography between the ARS System and the test article. Spacecraft access issues need to be forecast ahead of time along with access for configuring the spacecraft (e.g., connecting to an umbilical, instrumentation and closing hatches). The Direct Field Acoustic Testing  (DFAN) system will then be built up correctly to support the required test configuration. Because these tests are often the most time-limited, each test requires extensive planning and documentation to efficiently build the system in the correct logical order while remaining flexible to the many “curve balls” that happen during testing. ARS has also developed a protocol for using the NeutronTM System as an operational asset during testing. Utilizing the integral rigging points on the NeutronTM, we can deploy the Microphone Support Structure (MSS) along with a system supported strain relief to harnessing or fluid connections to the vehicle. This leads to a streamlined test without many of the access issues faced with having to build and use external systems like scaffolding. The MSS is also much safer for the flight hardware in terms of trip hazards.

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