In this answer to Why are there no robotic missions on Europa or Enceladus I wrote:
- Missions going through the ice and into the ocean are currently hypothetical and problematic. You need a lot of energy to get through 10 km of ice no matter how you do it, and unless your spacecraft is absolutely completely 100% certain sterile you may contaminate a lifeless ocean or disastrously infect it with Earth organisms. To my knowledge there is not yet documented capability that spacecraft can be absolutely sterilized and yet still functional.
Some life is easy to sterilize, but some isn't. We can say that Earth viruses and bacterial spores probably won't pose a threat to alien life and would be inert, but that's just wishful thinking and hand-waving.
There are even single protein molecules that can infect and kill animals and humans, something that was dismissed out of hand as impossible until enough people died.
So I'd like to ask:
Question: Is there any demonstrated or even proposed technology that can sterilize a spacecraft with 100% certainty and yet leave it electronically functional?