In the realm of (mechanical) testing in the space industry, especially for sensitive equipment like spacecraft and satellites, cleanliness is not just a preference—it's a necessity. And of course, acoustic testing is included. At MSI DFAT, we understand that the integrity of a testing environment directly influences the accuracy and reliability of our customers’ test results and the operation of their hardware. This article delves into our meticulous approach to maintaining clean rooms and equipment for direct field acoustic testing, ensuring optimal environmental conditions for each project.
Cleanroom Classes for Spacecraft Testing
For spacecraft testing, cleanrooms are classified based on the maximum allowable number of particles per cubic meter. The most common classifications are Class 100, Class 1,000, Class 10,000, and Class 100,000, with Class 10,000 being one of the strictest environments for spacecraft with optics. Many components are assembled in cleaner environments.
Class 10,000 (ISO 7) Cleanrooms: These facilities allow a maximum of 10,000 particles (0.1um or larger) per cubic meter of air. This level of cleanliness is essential for assembly, integration and testing of spacecraft with optical components that require high degree of protection from contamination. For these spacecrafts there is an allowable exposure time to be in less strict environments, but programs do not like to push these limits. Companies operating Class 10K cleanrooms employ advanced filtration systems, strict gowning procedures, and highly controlled access to maintain the integrity of the environment. When the area the spacecraft needs to go is not Class 10K, the whole spacecraft is “bagged” and a nitrogen purge is applied for a slight positive pressure inside.
Class 100,000 (ISO 8) Cleanrooms: These environments allow a maximum of 100,000 particles per cubic meter. While still providing a high level of cleanliness, Class 100,000 environments are the most commonly used facilities for assembly, integration and testing (AI&T). Many components are assembled in cleaner environments. All commercial communication satellites are assembled and tested in 100K facilities even with small optical instruments. These smaller components and optical systems are individually protected with covers or bags. These covers are removed during TVAC and dynamic testing. MSI DFAT routinely tests various spacecraft and satellites in Class 100,000 cleanroom environments, even those with 10K requirements.
These specialized facilities are essential for testing components of spacecraft, including propulsion systems, electronics, mirrors and delicate sensors. The goal is to ensure that no contaminants interfere with the spacecraft's performance, especially during critical phases of development and testing.
Cleanliness Measurement: Parts Per Million (PPM)
Class | >0.1 um | >0.2 um | >0.3 um | >0.5 um | >1 um | >5 um | FED STD 209E equivalent |
10 | 2 |
|
|
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| |
100 | 24 | 10 | 4 |
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| |
1,000 | 237 | 102 | 35 | 8 |
| Class 1 | |
2,370 | 1,020 | 352 | 83 |
| Class 10 | ||
100,000 | 23,700 | 10,200 | 3,520 | 832 | 29 | Class 100 | |
1,000,000 | 237,000 | 102,000 | 35,200 | 8,320 | 293 | Class 1,000 | |
|
|
| 352,000 | 83,200 | 2,930 | Class 10,000 | |
|
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| 3,520,000 | 832,000 | 29,300 | Class 100,000 | |
ISO 9 |
|
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| 35,200,000 | 8,320,000 | 293,000 | Room Air |
To quantify cleanliness in these environments, many companies use Parts Per Million (PPM) as a measurement method. PPM refers to the number of contaminants found in a million parts of air or material. In cleanrooms, achieving low PPM levels is crucial, as even minor amounts of contamination can significantly impact the functionality of sensitive equipment.
Controlled Separation of Equipment
One of our key strategies at MSI DFAT is the deliberate separation of our acoustic testing equipment from our off-the-shelf concert speakers. Our custom-designed and purpose-built MP series of loudspeakers for DFAT® are stored in a completely separate facility from the commercial-off-the-shelf (COTS) loudspeakers used for concerts and live sound events.
These two types of loudspeakers are managed and stored independently, minimizing the risk of contamination and allowing us to maintain stringent cleanliness standards. Our dedicated acoustic testing speakers and equipment are handled in specialized storage rooms designed to prevent exposure to dust, debris, and other potential contaminants.
Controlled In-House Logistics
To further enhance our cleanliness protocols, we employ dedicated trucks for transporting direct field acoustic testing equipment. Each truck is equipped to minimize contamination during transit, ensuring that our speakers, amplifiers, and cables arrive at the testing site in pristine condition. Our team follows strict procedures to clean and sanitize all equipment before and after each acoustic testing event, including wiping down surfaces and using appropriate cleaning agents. This process is a routine step in our preparation efforts for each acoustic test event.
Specialized Test Article Protection
To protect particularly sensitive components, such as satellites and other delicate instruments, some customers utilize specialized protective bags and containment systems. This additional layer of protection ensures that particles, particulates, dust, and foreign object debris (FOD) are kept away from critical equipment during testing, while minimizing mass-loading effects on the Unit Under Test (UUT). In some cases, the whole satellite is wrapped on Mylar sheets, other facilities have dropped a tent of the top of the satellite, including the locations for the microphones controlling the test. This requires MSI personnel entering the tent to place and calibrate the microphones to wear extensive cleanroom suits. All equipment is wiped down before entering the tent.
Example of a bagged and protected satellite.
Adherence to Cleanliness Protocols
We recognize that our customers often have their own environmental cleanliness protocols and standards, and cleanliness requirements widely vary according to the individual needs of any spacecraft program. At MSI DFAT, we fully adhere to these requirements, collaborating closely with our clients and their environmental cleanliness teams.
This partnership ensures that our testing processes align with their expectations, fostering a mutual understanding of the importance of cleanliness in achieving reliable results. Any company employing the direct field acoustic testing approach should adopt similar methods and practices to maintain cleanroom environments. We invite anyone to examine our loudspeakers and related equipment for dust using a white glove at any time.
Our Team in Action
To further illustrate our commitment to cleanliness, take a look at these photo examples of our test technicians, engineers, and operators dressed in cleanroom gowns and hairnets for 100K facilities, When testing in 10K environment, the garb includes hood, booties and gloves taped to the gown to prevent any particles from escaping. Their dedication to maintaining a clean and safe testing environment is evident in every aspect of our operations.
The MSI DFAT team in fully gowned for an acoustic test.
Invitation to Customers
We invite our customers to tour our facilities and witness firsthand our effective methods of maintaining cleanliness. Seeing our practices in action will provide you with confidence in our commitment to quality and reliability.
Cleanliness is a cornerstone of our approach to direct field acoustic testing at MSI DFAT. Through the separation of equipment, dedicated logistics, cleanroom environments, specialized protection measures, and strict adherence to protocols, we ensure that our testing conditions meet the highest standards. This commitment not only enhances the accuracy of our tests but also builds trust with our clients, reinforcing our reputation as a leader in the field of acoustic testing for sensitive equipment. By prioritizing cleanliness, we are better equipped to deliver precise, reliable results that our customers can depend on.
Launching things into space?
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