There’s one force whose effects are so deeply entrenched in our everyday lives that we probably don’t think much about it at all: gravity. Gravity is the force that causes attraction between masses. It’s why when you drop a pen, it falls to the ground. But because gravitational force is proportional to the mass of the object, only large objects like planets create tangible attractions. This is why the study of gravity traditionally focused on massive objects like planets.
Our first manned space missions, however, completely changed how we thought about gravity’s effects on biological systems. The force of gravity doesn’t just keep us anchored to the ground; it influences how our bodies work on the smallest of scales. Now with the prospect of longer space missions, researchers are working to figure out what a lack of gravity means for our physiology – and how to make up for it.
Freed from gravity’s grip
It wasn’t until explorers traveled to space that any earthly creature had spent time in a microgravity environment.
Scientists observed that returning astronauts had grown taller and had substantially reduced bone and muscle mass. Intrigued, researchers started comparing blood and tissue samples from animals and astronauts before and after space travel to assess the impact of gravity on physiology. Astronaut-scientists in the largely gravity-free environment of the International Space Station began to investigate how cells grow while in space.
Most experiments in this field are actually conducted on Earth, though, using simulated microgravity. By spinning objects – such as cells – in a centrifuge at fast speeds, you can create these reduced gravity conditions.
Our cells have evolved to deal with forces in a world characterized by gravity; if they’re suddenly liberated from gravity’s effects, things start getting strange.