Human life is cheap - we can get a reasonable astronaut to participate in a 10%-chance-of-death mission for about the same resources as participating in a 0.01%-chance-of-death mission; and it's just as ethical as, say, sending people to Iraq or to fly a test-plane like "SpaceShipTwo".

The only concern is if the advantages of having a human on-site justify the extra weight of the life support systems.