Designing Small Satellites: Mechanical and Systems Design Insights

At a Glance:

An overview of the mechanical and system design processes involved in microsatellite production.
A discussion of the various challenges associated with designing small satellites, along with a look at some of their trade-offs.

For millennia, humanity has looked up at the stars and questioned their place in the universe. Few things in life inspire as much awe and fascination as the celestial bodies we see orbiting around us in the night sky. Unfortunately, studying these objects is no easy feat, and even with all of the technology available to us today, it still remains largely unfeasible for society to invest resources in extra-solar space exploration.

Luckily, many of the questions we have about the composition and nature of rocky planets outside of the Solar System can be answered by observing our very own Earth from above, through small satellites that operate within Earth’s sphere of influence.

Microsatellites are changing the landscape of space technology. Engineers navigate a range of strategic decisions and challenges throughout the design and manufacturing process. Along the way, every choice, from component selection to system integration, requires careful consideration of tradeoffs that can influence performance and mission success.

Producing Miniaturized Parts for Small Satellites

To survive the harshness of space, manmade satellites must be resistant to very low temperatures and other extreme physical conditions. As a result, great care must be taken when deciding what kinds of materials satellite components should be made with.

While such a task is difficult enough for large projects such as the Hubble and James Webb telescopes, producing mechanical parts for micro‑satellites requires even greater precision in machining to meet the demands of space flight. Traditional CNC techniques remain feasible for most use cases yet can produce unneeded waste due to their inherent subtractive nature.

The emergence of digital design and 3D printing in recent years has opened new avenues for the development of more advanced manufacturing techniques, namely additive manufacturing. One such example is metal 3D printing, which can directly take CAD prototypes and turn them into flight-ready parts in a matter of weeks, reducing the overall labor required by humans. Components produced in this way can consist of titanium or aluminum lattice structures that are lightweight and provide efficient thermal cooling during launch.

While additive manufacturing can be advantageous over traditional CNC methods, they are not without their drawbacks. 3D printing overall is not as accurate as CNC machining, and more quality assurance checks are required due to increased complexity and process variability. Consequently, engineers employ topology optimization and other additive manufacturing principles in the design process to ensure a well-made component.

Payload Integration

Practically speaking, the main point of producing a microsatellite is to bring its payload into space. For missions of this scale, payloads usually involve various types of cameras, sensors or delicate scientific instruments used for Earth observation, communication or navigation. While the payloads themselves can be relatively simple objects, integrating them into satellites and ensuring their survival during launch is much more complicated.

One of the most important concerns to address is making sure that the payloads fit well within the casings of the satellite. Payloads often arrive in custom housings that must interface with standard deployer mechanisms (axial and radial) while accommodating differences in bolt patterns, stiffness and alignment. Imperfect alignments can introduce a variety of problems during ascent, potentially leading to mission failure.

The challenges of payload integration do not end with mechanical alignment and fit, however. Once everything is in place physically, electrical wiring and data cables must also be connected to various sensors in a precise manner. Different types of payloads require different types of connections, which all must fit through narrow pathways in the already small frame of a micro-satellite.

Another consideration for engineers concerns how to account for vibrations and shaking experienced during launch. While in liftoff, launch vehicles can experience random vibrations that can perturb assemblies onboard satellites. Given enough of a perturbation, satellite components can be ripped from their housing, potentially damaging the payload.

To prevent this, shock absorber padding (usually made of silicone) can be inserted into the satellite’s payload chamber, or gyroscopic systems can be introduced. Recent advancements in vibration dampening technology also make maglev suspension a possibility.

After payload integration, the final hurdle engineers face is to ensure structural integrity via rigorous environmental testing, which is often more brutal than the conditions experienced by the satellite during its mission. Once all tests are passed, the payload-carrying satellite is cleared for flight.

Design Trade-offs

In microsatellite mechanical engineering, every design decision affects the structure’s mass, volume, thermal behavior and reliability. Recognizing and managing these trade‑offs is critical for achieving mission success.

While metal 3D printing and other additive manufacturing techniques can significantly reduce the mass and thickness of satellite components, the inherent lightweightedness can increase vulnerability to launch perturbations. To mitigate this effect, engineers can use perforated materials that keep the weight off while also allowing for structural rigidity. Finding a balance between mass allowance and structural stiffness requirements is crucial.

Another important trade-off to consider is the simplicity of thermal regulation systems compared to the overall mass of the structure. Passive thermal management methods such as multi-layer insulation (MLI) blankets or thermal straps add a small amount of weight to the system but can increase the likelihood of mismanaging hotspot gradients.

On the other hand, active thermal systems (i.e., heat pipes and pumps) can control temperatures more consistently, but add more mass and overall power consumption requirements to the satellite.

A satellite’s mission plan depends strongly on the capabilities of its components. Of course, there is a strong correlation between a component’s capabilities and its cost. This correlation introduces another trade-off for engineers to consider: “How can a highly capable satellite be built while minimizing costs?” The answer to that question lies in the overall goals of the mission. Prioritizing what matters most influences what structural and cost constraints can be relaxed and which require conservative design.

Microsatellite Systems Design

For a satellite mission to be successful, each of its subsystems must cohesively work together. This is where overall systems design becomes important, and where many engineers spend a lot of time and resources.

The systems design process often starts with choosing a suitable overarching design philosophy. Perhaps one of the most used methodologies is the “Vee” method, which is used to visualize the development lifecycle of a system in a “V” shape.

In the diagram, the left side represents definitions and problem decompositions, while the right side represents integration and verification. Together at the apex (bottom of the “V”), the two sides merge into implementation. This design process allows engineers to iteratively develop the satellite system and simultaneously address mechanical trade-offs.

Ultimately, a satellite’s value can be evaluated by the sum of all of its subsystems, which can be maximized through effective systems engineering.

From Concept to Launch

Microsatellites may be small, but the journey towards manufacturing one is anything but. From very precise additive manufacturing to carefully unifying their various subsystems, every step of the design process demands rigorous planning and engineering discipline. In the end, the development and launch of microsatellites provides a cost-effective way to learn more about our planet, while also leading advancements in everyday communication and navigation.