Humans in Space

Hi, I’m Marley the astronomer here at the Space Centre. This month we are focusing on humans in space! With space agencies around the world developing their own space stations, and some looking at sending people to the Moon and beyond, the health and wellbeing of these astronauts is extremely important.

The furthest human beings have gone is the Moon. 12 different astronauts landed on the surface and spent a few days there. In the future, we anticipate these missions to look different. Astronauts could spend up to 3 months in the lunar environment. They will live on either the surface, or in orbit. Because these astronauts will be far from home for an extended amount of time, this means that they will face different risks to their health and wellbeing. NASA uses the acronym RIDGE to refer to these risks: Space Radiation, Isolation and Confinement, Distance from Earth, Gravity fields, and Hostile/Closed Environments.

Most research into the health of astronauts is done onboard the International Space Station. People have continuously lived onboard the station for over 20 years, and in that time over three thousand experiments have been done. Many of these experiments focus on the impacts of RIDGE.

If astronauts were to travel to Mars, they would experience three different gravity fields. Facing weightlessness during their 9 month journey, then Martian gravity at about 1/3rd to that of Earth’s for the duration of the surface mission. Finally, when the astronauts return, they would have to reacclimatize to the gravity of their home planet. After studying what happens to astronauts before and after they have been in space, scientists now know that without Earth’s gravity, the human body undergoes many negative changes. For instance, bones weaken, and muscles lose their mass faster than they would here on Earth. On Earth, our bones on muscles support our weight. When in a microgravity environment, the bones and muscles don’t have to do any work, leading to them weakening. Finding a way to mitigate these effects before astronauts travel into deep space is very important.

Two experiments that are studying the impact of gravity on human cells are Cardinal Heart  and Human Muscle-on-Chip. Both experiments use a technology called a tissue chip. These are very small devices that have living cells in them. These cells mimic the same complex functions of human cells. Cardinal Heart used tissue chips with engineered heart tissue (EHT), and Human Muscle-on-Chip used tissue chips with models of muscle fibers created from cells of both young and older adults. Using these chips, scientists can test the effect of different drugs to treat the effects seen from being in a non-Earth gravity environment. The chips are more predictable, and provide very fast results. After collecting data, scientists can predict changes on the time scale of days or weeks, instead of months or even years.

Not only could the results from tissue chip studies help astronauts, they could help people on Earth as well. The physical changes that astronauts experience in microgravity are similar to age-related diseases people on Earth experience. This means that the results of Cardinal Heart can help prevent cardiovascular problems for people in space, and help develop treatments for heart disease here on Earth.

Astronomer’s playlist

60 mins

Also important for human health is, of course, food! But not all food is allowed to travel in space! In this activity, you will learn about sensory evaluation – a test that scientists do see if foods qualify for spaceflight.

Ask yourself: What food would you miss the most while in space? Would it qualify for space flight?

30 mins

Returning to Earth can be very challenging for astronauts who have spent months to a year away from our gravity. Returning from the ISS, astronauts can experience dizziness, loss of balance, and even nausea. In this activity, you can mimic the impacts of reentry.

1 day

Earth’s gravity has impacts on our body we might not even think about. In this activity, you can see the effect of gravity on your height.

Ask yourself: Would the results be the same on the Moon? On Mars? What would happen in weightlessness?

Still curious about tissue chips? You can read about them here. Cardinal Heart was on the ISS from October 2020 – October 2021, and Human Muscle-on-Chip was onboard from October 2020 – March 2023.

Ask yourself: What other technologies developed for use in space have use on Earth?

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