Keeping humans healthy in space

The return of Sunita Williams and Barry "Butch" Wilmore from the International Space Station has sparked public interest in the health implications of spending long periods in space.

- DEVANGSHU DATTA

The duo were up for 286 days instead of the eight originally scheduled.

Keeping people healthy in space is a complex task. Fifty years of research into this has resulted in major advances in our understanding of the body, and the development of many useful tools.

Running space stations, (or taking trips to Mars as NASA plans) involve very long stints in space. It should be noted that Williams and Wilmore were nowhere near the record. Indeed, this wasn't even the 10th-longest unbroken period in space. More than 20 astronauts and cosmonauts have spent over 300 days in space at one go, and quite a few have logged over 800 days spread across multiple missions.

The record for the longest single stay was set by Valeri Polyakov, who spent a whopping 438 days on the Mir Station in 1994-95. Polyakov died in 2022, at the ripe old age of 80, 27 years after returning to Earth and continuing to work in the aerospace industry.

Space travel places several unusual stresses on the body. One is due to acceleration, as a rocket gains speed. Acceleration pressures are often measured in "g"s - that is, multiples of gravity. Gravity at sea-level exerts a downwards acceleration of around 9.8 metres per second every second (the velocity of a fall increases by 9.8 metres every second if you jump out of a plane). During sharp acceleration, fighter pilots can endure the equivalent of 9-11 times that of gravity.