It is hot, cold, and full of radiation, and the absence of gravity only worsens the conditions. For this very reason, many of the spacecraft’s components must be custom-built for this unforgiving environment, and one of the most important parts is the aerospace bearings. These components are used in even the most minor moving systems on both spacecraft and satellites, such as robotic arms, antennas, and propulsion systems.
The Challenge of Space Environments
Unfortunately, space is not like Earth. Traditional machine grease and oil cannot help outside our planet’s atmosphere and are useless in the vacuum conditions of space. These lubricants can easily evaporate or be blasted off by radiation in the harsh environment in space, making them unreliable and, often, a hazard. Space-rated aerospace bearings need both added protection and are often rated to last for many years without the benefit of a helping hand to fix unforeseen issues. This has been a challenge aerospace engineers have been working on for some time.
Innovations in Bearing Materials
Aerospace bearings today utilize materials that go far beyond the humble steel. Now, advanced silicon nitride ceramics are used for the bearings. This material is relatively light, doesn’t wear down like steel, and works at high temperatures. The best part for space use is that they can do all this without needing a liquid lubricant, perfect for the vacuum of space.
However, research in bearings material has gotten even better: Lubricated coatings on bearings are now a popular material for space use. Engineers can utilize coatings of solid lubricants like molybdenum disulfide and diamond-like carbon in the bearings of current space missions. These lubricated agents can reduce friction and extend the life of a bearing, keeping precious space hardware running for years without replacements.
Applications in Spacecraft and Rovers
Satellites, planetary rovers, and space telescopes can now perform their missions without failure in large part thanks to these aerospace bearings. For example, the Mars rovers use sturdy bearings that operate in high-speed conditions and temperatures hundreds of degrees below zero. The James Webb Space Telescope includes high-precision bearings in its design to move its secondary mirror in order to focus on distant stars and galaxies. If not for aerospace bearings and the research to develop more reliable, high-temperature materials, all these missions would have likely failed due to mechanical errors.
Propulsion systems also need aerospace bearings that can operate in a vacuum. Ion propulsion, a propulsion technology that uses electrostatic or electromagnetic fields to accelerate ions to generate thrust, can last thousands of hours of operation with the right kind of aerospace bearings made of silicon nitride. In some designs, the bearings can last for the entire duration of a spacecraft’s mission without failure, allowing them to perform multiple missions and never wear out.
Testing and Quality Control for Bearings in Spacecraft
Bearings are subjected to rigorous testing to ensure that they’ll function in high vacuum, and when exposed to temperature extremes, radiation, and while subjected to microgravity conditions. This includes mechanical, environmental, and load testing, as well as non-destructive methods such as X-ray imaging to detect imperfections in the structure. This need for precise reliability, strength, and performance is crucial for space voyages which will last many months, and possibly years, as failure of even the smallest component can be terminal.
The Importance of Reliable Bearings in Aerospace
Every part of a spacecraft has to perform, and bearings are no exception. A single bearing failure can bring a mission to a grinding halt, require expensive repairs, and in the worst cases, mission failure. Advancements in materials and techniques mean reliability for the future of space applications. As humans look to the stars, bearings continue to shape the way we get there.
