In microgravity, the human spine lengthens by as much as five centimetres, and astronauts come home temporarily taller than when they left, before gravity compresses the column again within days of landing - Space Daily

What the report says

Space Daily reports that astronauts returning from extended time in orbit can be temporarily taller, with typical gains described as about 1% to 3% of standing height — roughly up to five centimetres for a person around 1.8 metres tall. The increase fades within days after landing as Earth’s gravity again compresses the spinal column. The article frames the effect less as a novelty than as a practical issue for spacecraft, spacesuit and seat design.

The report reviews earlier measurements, including Apollo-Soyuz and Skylab observations, and cites scientific reviews noting that height gain tends to occur early in flight and then plateau. A common explanation is that spinal discs expand when they are no longer loaded by gravity, but Space Daily notes that direct evidence during flight remains limited. It also cites NASA’s explanation that the spine’s natural curves may straighten in microgravity, making the body longer.

The issue matters for crew safety because astronauts must still fit suits and vehicle seats after their bodies change in orbit. Space Daily says suit torso length includes an allowance for spinal elongation, while tight seat layouts, such as those considered for Orion, make seated height especially important. If a crew member cannot fit properly for re-entry, the problem becomes operational rather than merely medical.

The article also highlights concern around the return to gravity. It cites research finding higher rates of herniated discs among astronauts than matched controls, while noting that much of the evidence comes from earlier spaceflight eras and that current risk under modern exercise routines is not well defined. Space Daily says researchers have called for more routine in-flight measurements, imaging before and after missions, and longer post-landing injury tracking, especially as Artemis and future Mars missions could place crews far from immediate rehabilitation support.