NASA, SpaceX and numerous other companies are flogging the possibility of deep space travel to Mars. But, problems in doing so keep cropping up and here is another one. Sending astronauts on long journeys is likely to destroy their intestines and give them cancers. There is no effective shielding today from injurious rays that would affect them. This is not surprising. The human body is not made for space, and traveling off this planet means carrying everything with one to survive. The barriers so far do not appear to be insuperable, but the question arises again why NASA and others are so anxious to launch man into space when robots are so effective in doing the job. Nevertheless, the publicity continues.