Steven Hawking chimes in on the debate about whether to spend valuable resources sending humans on planetary exploration missions, or to use robots. After all, it's a lot cheaper to send a machine that doesn't need oxygen, isn't sensitive to radiation, and doesn't need to be returned to their family at the end of the mission. But there are some legitimate scientific reasons to send humans including real-time tweaking of the chemistry experiments looking for life, and to initiate unplanned tests based on unexpected observation. Also, the tax-paying public gets more emotionally invested in human missions and would possibly be more willing to continue funding. The ultimate answer is likely a mixture of the two, but exactly what that mixture will be is still being hotly debated.