By Mark Horstman
ABOVE us right now a team of astronauts is carrying out amazing experiments into the best way for humans to live in space and get back safely.
Research into long stays in space is important to prepare astronauts for missions to Mars, which the US space agency NASA hopes will happen by 2030.
Commander Peggy Whitson is in charge of the International Space Station and has spent more time there than most.
As you read this story she’s orbiting 400 kilometres above Earth, and in late April she set a record for a US astronaut: more than 540 days in space since 2002.
She’s also done eight spacewalks, more than any other woman.
“The International Space Station is providing a key bridge from us living on Earth to going somewhere into deep space,” she told the US president, Donald Trump, in a video call on April 24.
Hostile to life
Living with microgravity weakens your bones and muscles, and can change the pressure inside your eyes. Astronauts experiment with different exercises and diets to make sure they can walk and see properly after a long journey.
Without the protection of Earth’s atmosphere and magnetic field, astronauts are exposed to much more radiation from space, which can damage cells in the body.
The space station is a giant lab that tests how to shield astronauts from radiation. Bacteria, yeast, plants, fish and mice are on board to compare changes in their DNA with their Earth-bound cousins.
Ultimate recycling scheme
A mission to Mars taking several years would need a life-support system that recycles everything.
The International Space Station uses solar power to break water molecules into oxygen and hydrogen. Astronauts breathe the oxygen in and the hydrogen mixes with the carbon dioxide they breathe out to make more water.
“Water is such a precious resource up here, that we also clean up our urine and make it drinkable,” Commander Whitson told Mr Trump. “It’s really not as bad as it sounds.”
“Well, that’s good. I’m glad to hear it,” he said. “Better you than me.”
When she returns in September, Commander Whitson, 57, will have spent more than 650 days in orbit. The world record for the most time in space by any person is 879 days, held by Russian cosmonaut Colonel Gennady Padalka.