Kris Lehnhardt is a medical doctor working at NASA JSC in the Human Research Program. Kris leads the science side of the XMC team, which develops medical systems that enable future human exploration beyond low Earth orbit (LEO). In our discussion, we cover the fundamentals of designing human-rated spacecraft, how NASA has changed its approach over the years, and what we need to do to keep humans healthy when going beyond LEO for long durations.Timestamps: