Satellite Cleanrooms – Design, Garments, and Contamination

Satellite Cleanrooms – Design, Garments, and Contamination

Satellite Manufacturing Cleanrooms

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 deployed 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. A combination of softwall production areas and hardwall cleanroom facilities provide isolation of critical tasks. Depending on the level of particulate controlled required, a softwall cleanroom may be deployed 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, those that will journey the far reaches of outer space, 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. 

Preventing Extra-Terrestrial Contamination

A satellite cleanroom prevents earth-borne contamination from invading extraterrestrial environments. Upon a satellites commissioning, the project undergoes a review to establish a threshold of allowed microbial counts based on a risk assessment. Based on jurisdiction, a guideline is set forth by the COSPAR Planetary Protection Policy, NASA’s Planetary Protection Office, or the European Cooperation for Space Standardisation.

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

While it might seem like science fiction, aggressive space fungus that mutates into a more virulent strain is not far-fetched.

“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 (10-1-00)

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 that 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 .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.

Hubble Space Telescope

In 1990, the Hubble Space Telescope left a team of scientists dumbfounded after discovering that 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 satellites focus. In comparison, the average blood cell is roughly 5 micron.

Cleanroom Particulate

A human hair ranges in size between 17 – 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. Cleanrooms remain a key barrier against contaminants, biofilms, and trace moisture. This reduces the risk of fault and failure within housings, gyroscopes, sensors, or heat-abating materials.

Contamination Control - Tools & Techniques

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 proven 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 .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

James Web Telescope in Cleanroom Environment

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. Minimizing the number of operators reduces airflow disruption and prevents overcrowding. Satellite cleanrooms require housing of extraordinarily large components, if not the entire satellite assembly under one roof. 

For large teams, who may exit and enter the cleanroom multiple times daily, automating the gowning process is a way to increase the speed and ease of entry and exit. When crunching the numbers, saving an operator just 1 – 2 minutes each 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. Dedicated gowning areas allow operators to change out of street clothes and into garments designed for cleanroom use. A gowning room is strictly divided 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. 

Automatic Shoe Cover Machines

All entries and exits from gowning rooms, especially at high-volume, amplify the risks of contamination and accidents. Bending over and standing on one foot both create opportunities for loss of balance and falls. Furthermore, bacteria are easily spread from our feet to our hands by touching walls, the floor, or our shoes in the gowning process. Automatic shoe cover machines maintain spatial barriers and streamline floor layouts by eliminating seating benches and the need to awkwardly balance on one foot or wait for an open seating bench. 

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