When a space mission returns a sample from a planet that may harbor life, there is a risk that that life may be something that earth immune systems can not handle. NASA is planning a sample return from mars. Several scientists are concerned about the risk.

The problem was recognized during the Apollo moon landing program. The moon appears dead, but NASA recognized a small chance that some kind of life might reside there. Therefore, NASA spent millions on a lunar receiving lab. They planned to bring the first astronauts and their lunar samples into a quarantine trailer, move the trailer to the receiving lab, and test them carefully before release. They planned a secure plastic corridor between the capsule and the trailer. But in practice that seemed too much trouble, so the astronauts cracked their hatch in the ocean, emerged in masks, and walked to the trailer. If nasty organisms had been present, they could have escaped at that point.

We need to learn from this. It is silly to spend millions and then compromise planned protocols. I suspect that there is a conflict between the folks that take these things seriously, and those who don't. Our role is to advocate seriousness.

Here are some folks who are concerned about this issue:
http://www.icamsr.org/protection.html