Space is filled with all kinds of things that are unkind to cloth, such as dust and radiation, and they are the reason why sticking a nylon national flag on the moon isn't permanent.
In my world I would like my space pirates to compete for territories and even collaborate with corrupted government bodies, but that means they must leave their mark for a very long time. For this very reason they need flags — durable and easily noticeable flags that can withstand hundreds of years.
The tech level is 100 years from now and I have considered using holographic projection, but that might not work in empty space.
Question: What can I use to make a permanent flag (call it a "trademark" if you will, pirates aren't picky) that will mark a spot or territory planetside or in space?