Science is the main purpose of the ISS. Space agencies from the U.S., Russia, Europe, Japan, and Canada all have laboratories aboard. But other countries and commercial firms can send up their research too. As of 2015, more than 1,700 experiments had been conducted on the ISS!
The space station is in such high demand because it offers an environment unlike any on Earth: microgravity, in which objects appear to be weightless. Many substances behave differently in microgravity. Fire is one example. A candle flame burns in a bluish sphere instead of the familiar red-orange cone we see on Earth.
Researchers on the ISS have also had to come up with innovative solutions to deal with the challenges of space travel and living in cramped quarters. Some technologies we use today, like water-purification systems and a surgical robotic arm, were inspired by work done on the ISS.
The astronauts themselves are an experiment too. NASA hopes to send people to Mars by 2030. But before that, we need to know how outer space will affect human bodies in the long run. We already know that muscles and bones get weaker in the absence of gravity—that’s why astronauts have to run on the treadmill, ride a stationary bike, or lift weights for at least two hours every day. Long periods in space can also cause vision problems, make the heart smaller, and lower the immune system’s ability to fight off diseases. There’s also the psychological impact of being confined in a small space so far from home.
One surprising effect of living in space: Your sense of taste is dulled. That’s because microgravity affects the way fluids move in your body. “You feel like you have a mild cold all the time, so things don’t smell or taste as good,” says Wolf.