Today I finished the game for the first time. I played the campagin on Insane difficult level if it is relevant.

And the ending I got has been the same you can see in this walkthough: https://youtu.be/jQ5RFBo0L_U?t=19040

Since I liked the game so much, I wanted to play the final level again in much more relaxed mood. So using the main menu I started the Ymirus level with minimum difficulty level. I was suprised that the Iberia messages were different in very first room. Playing throught the level again it was clear that it was a different scenario where the main character could not rescue anyone! The ending is also different, the Iberia crashes on Ymir to destroy the evil AI and you are left drifting on the space on a cryotube...

I did like the story of the game, but I am surprised there are multiple endings. My question is then, are there more? How to obtain them?

Judging by the achievements, there are two endings - the "Beale Ending" if you rescue all cryopod survivors, and the "Trinidad Ending" if you fail to do so.