Crap, how did I miss this one??? A free online course on Future Learn: "How to Survive on Mars: the Science Behind the Human Exploration of Mars" from Monash University in Australia. It is subtitled "Learn the basic science needed for humans to survive on Mars, with this free online science course". Sadly, it has come and gone (it's a 4 week thing that started in October of last year), but hopefully it will be offered again some time. Either way, there's a cool introductory video to watch at the above link.