Cleanrooms protect satellites or spacecraft components from particles, residues, or bio-films that corrode electrical systems, hinder performance, or hamper longevity. Satellites often reach a lifespan of roughly 15 years or longer. Once a satellite reaches orbit, 355 miles above the earth’s surface, at a speed of 18,000 miles per hour, making laps of the earth every 97 minutes — a hands-on repair during a spacewalk is a worst case scenario.
Cleanroom preparation minimizes late-cycle defects by reducing production variables. Every cleanroom is unique. Depending on the application and sensitivity of the device in question, a different cleanroom design may be necessary to balance cleanliness with operating costs.
Cleanroom Design for Communication Satellites
For communication satellites that remain within earth’s orbit, an ISO Class 6-8 cleanroom allows sufficient particle and contaminant control. Cleanroom engineers design each space so that particles from production surfaces are whisked away from critical components. In any case, a combination of softwall production areas and hardwall cleanroom facilities provide isolation of critical tasks. Depending on the level of particulate control required, a softwall cleanroom may be necessary for mobile transport, while a modular hardwall cleanroom provides dedicated HEPA filtration in the most critical areas.
An ISO Class 8 environment is about 10x cleaner than average room air. For the most critical satellites, cleanroom conditions require air quality that is roughly 100,000x cleaner.
Cleanroom Design for Exploration and Deep Space Satellites
Satellites destined for the outer reaches of space demand greater consideration for microbe counts. An ISO 3 cleanroom (Fed. Class 1) is one of the cleanest human-ready environments on earth. Partitioned cleanrooms with air lock entry systems assure that entry and exit does not introduce contamination.
Equipment, tools, raw materials and packaging are wiped down and enter through integrated passthrough chambers. Items that require sterilization are aseptically processed with IPA wipedowns, autoclaves or by gamma sterilization.
Additional Reading: PAC Designs a Crucial Cleanroom Facility for the Webb Space Telescope
Preventing Extra-Terrestrial Contamination
A satellite cleanroom prevents earth-borne contamination from invading extraterrestrial environments. So, upon a satellite’s commissioning, the project undergoes a review to establish a threshold of allowed microbial counts based on a risk assessment. Depending on the jurisdiction, the COSPAR Planetary Protection Policy, NASA’s Planetary Protection Office, or the European Cooperation for Space Standardization set a guideline.
Neutralizing microbes on interstellar space vehicles is a principle of a do-no-harm approach. If the solar systems or galaxies beyond ours are teaming with life, it’s possible that rogue earth microbes, such as fungus, bacteria, or even viruses could colonize or even cannibalize other life on distant planets and spacecraft. In the harsh conditions of outer space, the survival of fungus and other microbes is well documented.
Fungal Contamination in Outer Space
On space missions, the potential problems multiply because of increased radiation that can cause the fungi to mutate into more dangerous forms. Francis Cucinotta, manager of the radiation health office at NASA’s Johnson Space Center, said he published a scientific paper in 1995 that found that about one-tenth of 1% of bacterial spores would mutate after a year of the kind of radiation experienced on a mission to Mars.
The Boston Globe, October 2000
Microbial damage to components could unhinge a space mission. Mold thrives in dark, damp, hard-to-reach locations. Once established, eradicating a fungal invasion within an air conditioner, amongst electronic cables, or behind control panels is extremely challenging. Generally, fungal protection requires tight control over humidity and temperature. On the International Space Station, HEPA filtration provides a constant source of temperature-controlled air. This air filters out 99.9% of all microbes and particulates.
Protection of Precision Optics and Laser Devices
Lenses designed for outer space are incredibly precise. According to NASA, the Hubble Space Telescope maintains a pointing accuracy of 0.007 arcseconds, even within terrestrial atmospheres. In layman’s terms, that’s the optical equivalence of shining a laser onto the head of a dime from 200 miles away. Hubble can differentiate two fireflies in Tokyo, from the distance of Washington D.C., or casually spot a nightlight on the surface of the moon.
In 1990, the Hubble Space Telescope left a team of scientists dumbfounded after discovering images sent back from space were of much lower quality than expected. A primary mirror panel installed just 2 microns too flat prevented proper light reflection and misaligned the satellite’s focus.
With challenges like this one, the Hubble telescope taught the scientific community many lessons about optics technology and its protection. Now, thirty-one years later, Hubble is one of the most successful telescopes ever built. Not only has it given us a better understanding of astrophysics and planetary science, but it has contributed to the impressive advancement of precision optics and the manufacturing of technology for their protection.
Reduction of Particulate Contamination
A human hair ranges in size between 17 and 181 micron (millionths of a meter). Skin particles, hair, nails, and other traffic-borne contaminants are a serious concern for ultra-precise manufacturing. The human body sheds 100,000+ cells with each step, therefore gowning procedures and cleanroom garments help curb any contaminants introduced by human operators.
Thermal sensitivity, aerosols, human-borne contaminants, and microbes are among many threats to space telescope mirrors and laser systems. Moreover, cleanrooms remain a key barrier against contaminants, biofilms, and trace moisture. So, this reduces the risk of fault and failure within housings, gyroscopes, sensors, or heat-abating materials.
Contamination Control: Tools & Techniques
Cleanroom Curtains
On December 11th, 2021, the James Webb Space Telescope (Webb) was placed atop the Ariane 5 rocket, in preparation for its launch from the Europe’s Spaceport in French Guiana.
According to the European Space Agency, the Webb is the next great space telescope following Hubble. Its mission is to answer outstanding questions about the Universe and see farther into astronomical discoveries: from the formation of stars and planets to the birth of the first galaxies in the early Universe.
With such an important mission in mind, the Webb telescope placement was accomplished under strict safety and contamination control protocols. So, a cleanroom curtain 12m high and 8m in diameter were installed between the two platforms to create a sterile space around the Webb and protect it from any contamination.
Cleanroom curtains offer versatility and reliability better than any other product. Furthermore, they can be used with framing to create a cleanroom or independently – like in the case of the Webb telescope – to create areas protected against contaminants.
Contamination Control Flooring
Foot traffic and carts transfer organic matter, grit, and grime but also pathogens and manufacturing byproducts from dirty areas to cleaner ones. Tack-regenerating mats are a scientifically provable measure against vectors of infection and contamination. Deployment reduces colonies of Staphylococci, Gram-positive bacilli, and Aspergillus Fumigates in aerospace applications, but also in hospitals, ICUs, laboratories, and data centers.
A particle under 50 microns is non-viable, meaning it’s undetectable by the human eye. At 60 microns, a dust speck in a sliver of sunlight is easily detectable compared to micro-particles or pathogens as small as 0.5 – 10 microns. Smaller than a living cell, and only visible under powerful microscopes, buoyant particles act as aerosols. After many hours, suspended particles eventually settle until the next production cycle.
What’s the Most Effective Method of Reducing Particles?
Preventing the introduction of particles is the most effective control method for curbing cleanroom contamination. Before entering a cleanroom environment, the primary control is proper hygiene and systematic gowning. In a cleanroom, everyone still puts their pants on one leg at a time, however, there are a few added measures of protection.
Gowning and Garments
Satellite manufacturing requires large-scale teams. For some cleanrooms within a pharmaceutical or hazardous compounding sector, a cleanroom area may only consist of a few hundred sq. ft. Thus, minimizing the number of operators reduces airflow disruption and prevents overcrowding. Satellite cleanrooms require the housing of extraordinarily large components, if not the entire satellite assembly under one roof.
Generally, for large teams, who may exit and enter the cleanroom multiple times daily, automating the gowning process is a way to increase the efficiency of entry and exit. When crunching the numbers, saving an operator just 1 – 2 minutes a day can result in tens of thousands of dollars in time savings. Additionally, the increased production generated with the time savings contributes to project completion and fiscal goals.
Gowning and Protocol
Gowning rooms allow swift entry and exit from a cleanroom without introducing human or equipment-born contaminants. Furthermore, dedicated gowning areas allow operators to change out of street clothes and into garments designed for cleanroom use. A gowning room has a strict division between clean and dirty areas. Generally, cleanroom coveralls feature blended polyesters that prevent fiber shedding. Hoods, masks, and boots prevent hair and skin particles from reaching critical surfaces. Likewise, the static-free materials prevent the hitchhiking of particles via static cling.
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