First and foremost, I am a paramedic and a paramedicine educator. But last year I woke on Sol 12 of an immersive Mars mission simulation to observe small confined crews in a Mars analogue as the crew medical officer. But it was raining. While the crew memebers watched the rain from the habitat window somewhat perplexed, it began to sink in. Physically Mars has no atmosphere, therefore it does not rain on Mars. Any attempts of the crew members who were engaged in the simulation to ignore it (the rain) or alter the simulation to allow its presence would negate the very objectives of the simulation.