How is Equipment Lubricated in Space?

The space industry is unique because it must optimise for multiple environments. Tribologists must provide protection on the ground, during launch phase, low earth orbit, and deep space, which is also very different to re-entry.

Juan Flores Preciado (SpaceX): 

Non-space environments in the space industry

On your launch site it’s very important than to protect equipment against corrosion. We typically do not have a lot of systems that rotate at a hundred thousand RPM. We do have a lot of systems that have to withstand very heavy loads and any rotation is slow. But we have a lot of components that will require some lubrication and corrosion protection at the same time. 

Many times the systems that need lubrication are exposed to the environment; there are no in cages to encapsulate it. Some of the systems that are located close to the launch pad may be exposed to high temperature. So we don’t use a lubricant that may not be able to withstand those temperatures or lubricants that may suffer degradation because of the contact with sodium chloride or sulphates or other kinds of chemicals in the environment. 

For the rocket; sections don’t really stay in space for a long time. They just launch, release a payload and then land. That application is almost like an airplane, in terms of like the type of environment and operations we need to consider. 

Space: the harshest lubricating environment

And then once you are in space you have to take many things into consideration.

Firstly there is no gravity/ So there is no way to put oil down to specific locations for liquid lubricants. Also the lack of oxygen. Many greases or lubricants require uh, some gases or moisture to form this famous tribofilm, or to form an oxide layer on the surface. 

We have a radiation issues in space. You have UV; not the regular UV that you experience on Earth, but UV without the protection of our atmosphere. That may interact with the molecules of your oil. The impact energy is so high that it’s just going to pull apart the carbons in in your molecules backbone.