From the Editors
Mechanisms, materials, structures: These are the supporting technologies that let the primary spacecraft systems perform their tasks; they're the "nuts and bolts" that enable effective and reliable function. This issue of Crosslink examines some of these enabling technologies, which are easy, but dangerous, to overlook.
Space system mechanisms, or moving mechanical assemblies, play a critical role at all mission stages, from holding a rocket on the launchpad to unfurling a solar panel to pointing a sensor or antenna. Some missions have failed because of deployment problems; without the precise and reliable function of mechanisms, more would surely be compromised. Many of these mechanisms would not last long without effective lubrication, which is the province of tribology. Aerospace expertise in this rather esoteric discipline has helped save missions in the past, and continues to extend the service life of mechanical systems in demanding environments. While some mechanisms must endure constant cycling for years in space, explosively activated mechanisms typically need to function only once—without fail. Aerospace has uncommon expertise in ensuring explosively actuated devices will perform as designed, conveying launch and space vehicles through the various stages of liftoff, ascent, and orbit.
Aerospace researchers are studying the latest trends in materials science, with an eye toward making space systems that are lighter, stronger, and better than their predecessors. Mass continues to drive space vehicle requirements, affecting both cost and performance. Aerospace has been studying historical mass property data in an effort to determine how best to predict the growth of a developing space program and quantify the costs associated with that growth.
Perhaps the most central supporting technology—quite literally—is the vehicle structure. Structural design is a delicate balancing act, which must constantly adjust to meet the conflicting demands of strength, stiffness, and lightness despite changing mission requirements.
All these components must be properly tested to ensure mission success; but in validating flight hardware, test engineers face a difficult challenge in looking for flaws without compromising the parts they're testing. Recent advances in nondestructive evaluation techniques are helping to improve the process. Even electronic systems have parts that can fail mechanically, and Aerospace has been active in developing models to help determine the risk of such failures.
We hope this issue will illuminate the important supporting roles played by mechanisms, materials, and structures in the space industry.
