Theres an invincibilty bug on that planet.
Im not exactly sure how to do it but i just put the shield on and got a huge group of Yetis all attacking me then poof, ratchets body became invisible and couldnt be harmed, i found it totally by accident, it resets when you die or leave the planet.
That way i could just stroll through and focus on getting the crystals instead of the Yetis, they do get in the way a lot its better than dying every 5 seconds.
Maybe if you try to google it there might be more specific details about it
Can't find anything about it…
Maybe my disc was damaged or something :P i was able to do it twice then left when i had all crystals