When building and testing complex satellites that must endure the rigor of the launch process, exist in harsh space environments, maintain lifespans between five to 20 years and beyond, and serve customers with absolute mission success, every detail matters—even a small dust particle.
These details are integral throughout the production process that take place in a clean environment. To develop and maintain cleanrooms for these space systems, every finite specific must be monitored, from the number of air particles per cubic foot to the relative humidity in the air.
Controlled environments for the space industry
Cleanrooms are used throughout manufacturing, including the space industry. Though cleanrooms have a similar purpose in the space sector, the cleanliness requirements can vary from visually clean to qualitative cleanliness verification according to mission type. Controlled environments are critical to meeting the mission requirements and the design life of the different vehicles developed for space system customers.
At Lockheed Martin, we build, test, and launch complex systems into space in a relatively short period of time. The production cycle time varies from a year to six or more years depending on the satellite design and procurement schedule. During the period of time when we are building and testing, we have to maintain these satellites and systems in a controlled environment and it needs to be maintained at all times, 24 hours a day, seven days a week.
Lockheed Martin Space Systems’ customers include the Department of Defense, NASA, and commercial businesses. Each customer supports different missions, which drive the type of cleanroom required to effectively process the assigned spacecraft. Lockheed Martin’s Space Systems Company maintains more than 370,000 square feet of dedicated cleanroom facilities.
Our satellites have a required design life—for some systems, as many as 15 years. The lifespan is critical to the missions we support. For instance, a spacecraft could take many years to reach its destination, as in the case of the Juno spacecraft headed to Jupiter. For spacecraft and satellites, it is imperative that they perform throughout the entire lifespan identified, as a spare or replacement is not readily available.
The importance of controlled environments to space vehicles
Cleanroom environments are important to achieving design life of space systems for several reasons. Any excessive amount of particles or residue on a space vehicle has the potential to degrade performance of the system. This is especially important on any mission that has optics as a payload. The lenses that are utilized in a satellite system are so exact that any particulate has the potential to reduce performance significantly.
The satellite performance may also be degraded from particulate or residue due to dynamic thermal properties in space. Any residue that is resting on the surface of blankets or mirrors on the space vehicle has the potential to absorb or reflect heat in space, which would affect the performance of the entire vehicle. Spacecraft can get very hot and, conversely, very cold; our systems are designed and tested to handle these extreme environments. Producing the systems in a clean environment ensures we can verify the integrity of the properties of our instruments while in operation.
Building the satellite in a clean environment also helps ensure the mechanics of different components mounted on the vehicle. As the satellite is designed to last roughly 15 years, we need to ensure no physical maintenance is required during that time period, because there is no current ability to repair autonomous systems deployed to orbit. The cleanroom prevents against particles settling on the vehicle that may corrode surfaces or cause resistance to the operation of mechanisms, avoiding potentially catastrophic effects on moving parts.
Lockheed Martin has a 40-year history of building spacecraft that have explored our solar system. International rules and standards are in place to address spacecraft cleanliness for “planetary protection” in order to preserve the scientific integrity of these missions for astrobiology research and to preserve these sites for future missions. In addition to stringent cleanroom protocols, frequent biological cultures made from assayed spacecraft hardware provide a measurement of cleanliness throughout construction. These assays primarily look for living microorganisms such as spores. A defined cleanliness threshold is established by the NASA Planetary Protection Office that must be achieved before spacecraft launch approval is granted.
Enabling a cleanroom workforce
At Lockheed Martin, the areas in which we build and design our satellites are specifically designed to meet the cleanliness criteria required for space systems. We call these controlled areas “high bays.” The ceilings of these cleanrooms are high because the satellites require anywhere from 40 to more than 100 feet in height to allow proper assembly of the major structural pieces. The air filtration systems that sustain the air quality of these high bays are specifically designed to support a high rate of filtered air. Cleanroom air control systems are unique and custom to allow that exchange of air up to 200 times a minute.
The requirements of these high bays and cleanrooms depend on the components and mission of the spacecraft or system. We design the various cleanrooms to align with IEST-STD-1246; they range from a class type that will control the area from 300,000 to 100 air particles per cubic foot of air. To manage fine particles in the air of these rooms, we filter the air using HEPA filters to take out fine particles and materials in the air.
To correctly maintain or keep a positive air pressure in the cleanroom, the entrances and exits of our high bays are made through air locks. Air locks are designed to maintain positive pressure in the high bays. Positive pressure is important to prevent external lower pressure and any containment from seeping into the area that would affect sustaining the desired standard.
Cleanrooms require training and self-discipline to maintain the desired environment and enable technicians and engineers to work on the space systems and components. These processes include having those who enter the cleanrooms gown up and put on the proper attire to ensure cleanliness levels. The maximum number people allowed in a large high bay can vary between 30-50 individuals. Employees that enter the cleanroom are required to don a bunny suit that covers clothes, hair, shoes, and facial hair. Gloves are worn to protect the surfaces of flight hardware from making contact with human oils and dead skin particles that could be corrosive to some flight surface materials. Grounding straps are also required to be worn around vehicles and components to prevent electrostatic discharge.
Focusing on mission success
At Lockheed Martin our large scale integration of space quality hardware involves highly complex and sophisticated equipment. In many cases this includes assets critical to our national security, science and exploration, and our commercial customers. Focusing on every aspect of our controlled environment from air particles to electrostatic charge is paramount to enable delivery of these complex systems to our customers and our nation, enhancing their life spans and mission success.
Juno Mission Overview
The Lockheed Martin-built Juno spacecraft was launched on Aug. 5, 2011. Juno’s goal is to understand the origin and evolution of Jupiter. As the archetype of giant planets, Jupiter can provide the knowledge we need to understand the origin of our own solar system and the planetary systems being discovered around other stars.
Juno will make global maps of the gravity, magnetic fields, and atmospheric composition of Jupiter from a unique polar orbit. Juno’s 32 orbits will extensively sample Jupiter’s full range of latitudes and longitudes. From its polar perspective Juno combines in-situ and remote sensing observations to explore the polar magnetosphere and determine what drives Jupiter’s remarkable auroras. The elliptical orbit swings below radiation belts to minimize radiation exposure.
Lockheed Martin designed, built, and is operating the Juno spacecraft for NASA’s Jet Propulsion Laboratory (JPL). The spacecraft is solar powered and spin-stabilized. Juno’s payload spans nine instrument suites, comprised of 26 separate sensors. The spacecraft started assembly, test, and launch operations in April 2010, was launched in August 2011, and will arrive at Jupiter in July 2016. The mission will end and de-orbit after over a year of science operations, in October 2017.
Tom Malko is Vice President of Assembly, Test, and Launch Operations (ATLO) for Lockheed Martin Space Systems Co., with major operations in Denver, Colo., and Sunnyvale, Calif.
Watch a time-lapse video of the MAVEN spacecraft during its Assembly, Test, and Launch Operations (ATLO) phase at www.cemag.us/videos.
This article appeared in the May 2014 issue of Controlled Environments.
