system
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human
[Star Trek] What would have happened if Spock's body had not been left on the Genesis planet in Star Trek II: The Wrath of Khan?

This is really kind of a STII and STIII arc question.

I haven't seen the movie since earlier this year so I'm not able to quote directly. But Sarek (Spock's father) asked Kirk why Kirk left Spock on Genesis. His body was dead though having been damaged saving the ship.

The story as we know has the regenerated body from Genesis taken to Vulcan in Star Trek III. What if Kirk had not left Spock's body on Genesis and had instead taken the damaged body to Vulcan? Could Spock have still somehow been resurrected?
gpt
It's very probable that Spock only died of radiation poisoning due to the horrible condition the Enterprise was in following the battle with Khan. If the ship had been crewed by anything other than a bunch of cadets, and the systems were in better shape, a medical team could have gone into the engine room and saved Spock. Or at the very least revived him soon after he fell unconscious. Granted, if the systems were in better shape, it's unlikely Spock would have had to sacrifice himself in the first place. 

Kirk left Spock behind because he saw "no future". No chance of even a miracle in the best-equipped medical facilities the Federation could offer. If he had even the slightest bit of hope, he would have kept Spock on board. 

So in your hypothetical, if Kirk kept Spock's body, it's possible he saw some avenue of reviving him. Or at the very least Sarek would have gone through the pains of having Spock's Katra reunited with his body via the fal-tor-pan ritual. 

Either way, the outcome is likely identical. Spock was coming back no matter what, it just took a little longer due to Kirk's decision to leave his body behind. 

In the worst case scenario, where Kirk brought Spock's body to Vulcan, but there was still no way to bring him back, Sarek would have likely had Spock's Katra transferred to a katric ark. Sort of a burial urn-meets-SSD, where the Katra can be stored almost indefinitely. Even though Sarek was fully Vulcan and lived his life accordingly, his human wife and half-human son had a profound affect on him, and he would have done anything to preserve Spock, or at least his memory.