Removed prior comment to fix a minor issue + add spoiler warning

01010101 01110100 01101011 00100000 01011010
01101110 01111000 01101011 01101011 00100000
01011010 01100011 01110101 00100000 01010101
01110100 01101011 00100000 01010101 01110100
01101011 00100000 01011010 01101110 01111000
01101011 01101011

hex:
55 74 6B 20 5A
6E 78 6B 6B 20
5A 63 75 20 55
74 6B 20 55 74
6B 20 5A 6E 78
6B 6B

ASCII:
Utk Znxkk Zcu Utk Utk Znxkk

Caesar cipher -6:
One Three TWo One One Three
1 3 2 1 1 3

I was not sure how you are supposed to use this.

I tried starting a new game and selecting the planet based on the numbers, e.g. 1 highest planet or furthest left. Either I did something wrong or it does not work.

The answer is described by @owen11 just press the corresponding button we the message occurs. The game was for me somewhat buggy because I often did not get any messages at all. Generally a restart of the game seems to fix it.

Your decryption was sufficient for me to get the result and achievement .
The numbers are the answers to the Unknown Messages.