A round-trip Mars mission could last roughly three years, and a model based on bone-density data from 69 astronauts predicted that everyone following the longer mission profile would return with osteo

The striking percentages came from a 2020 nonlinear model, not a Mars crew. Its input data predated current resistance exercise and stopped at 228 days, far short of the 1,000-to-1,200-day profile it projected. No astronaut has returned from Mars with osteopenia. No human being has travelled to Mars at all. The warning in the headline comes from a mathematical model published in 2020, not from a clinical follow-up of an interplanetary crew. Its authors took... [9881 chars]