The gist of it was:
"What if the only way to send astronauts to Mars is to leave them there for good? Lawrence Krauss, a physicist at Arizona State University and director of the Origins Initiative, argues that a one-way trip is worth considering, and that it wouldn't be hard to find passengers."
An interesting concept.
The argument is that a round trip would be exponentially more expensive.
According to the guest, he has been able to find quite a few people who would be willing to volunteer.