For all the hype surrounding crewed missions to Mars, and blind technological optimism that we already have all the tech we need to get people there and back safely; the reality is, we’re not ready yet. Reusable rockets, faster travel times, ISRU propellant.. it’s all wheel spinning if we can’t actually protect the crew en route, and back. The most important vessel is the human body; and it evolved on this planet, not in the extraordinarily hostile environments beyond our protective magnetic field (of which no human has ever been). Expect SpaceX (or whoever) will be going to Mars in 2024? Don’t count on it.