Kelly’s One-Year Mission represents a kind of dress rehearsal for a longer, straighter, and even more punishing voyage. In NASA’s Buzz Lightyear-esque formulation, it’s “a stepping stone” to “Mars and beyond.” At its closest, Mars is thirty-five million miles from Earth, and, under the most plausible scenario, getting there takes nine months. Owing to the relative motion of the planets, any astronauts who make it to Mars will have to cool their heels on the red planet for three more months before rocketing back home. What NASA learns about Kelly—at least, so the theory goes—will help it anticipate and overcome the challenges of interplanetary travel.
Makes sure you read this one all the way to the end.