International Space Station at 20: Former astronauts talk about living and working in space

The International Space Station (ISS) is celebrating a significant milestone, as the orbiting lab reaches its 20th anniversary of continuous human presence.

On Nov. 2, 2000, the first crew, Expedition 1, arrived at the ISS. NASA astronaut William Shepherd was the space station's first commander, paving the way for 20 years of humans living and working in low Earth orbit. Since that first historic mission, the orbiting lab has been continuously occupied by humans. 

Former astronauts Anna Fisher, Richard Linnehan, Jack Fischer and Barbara Morgan shared their experiences living and working in space during a panel hosted by Lynn Sherr for Viking.TV on Oct. 9. You can watch the panel online here.

Related: The International Space Station inside and out (infographic)

Challenges of living in space 

The space station is in low Earth orbit, meaning astronauts spend months in microgravity. However, weightlessness, or zero gravity, can have significant short-term and long-term effects on astronauts.

"You notice big differences in your body, specifically your muscles in terms of how much they atrophy in your legs [and] you have a fluid shift that occurs once you go into a micro-g or zero-g environment," Linnehan said during the interview, explaining how the fluid in the body normally held down by gravity on Earth shifts up into an astronaut's upper torso, chest and head. 

Linnehan has logged over 59 days in space, including six spacewalks totaling 42 hours and 11 minutes. He flew on STS-123, which delivered the Japanese Logistics Module and the Canadian Special Purpose Dexterous Manipulator, nicknamed Dextre, to the ISS in March 2008. 

"Everybody who goes into space feels really stuffed up — they have a massive head cold for a couple days," Linnehan said. Eventually, "you'll come to some type of steady state, where your body adapts to that environment and you feel better and then you can go about your daily chores."

In the microgravity environment of the space station, astronauts float around, so "up" and "down" mean different things than on Earth. Morgan, who flew on the ISS in 2007 as part of NASA's Teacher in Space Program, described feeling upside down for the first couple days on the orbiting lab. 

"There is no up or down in space," Morgan said. "Once your body does get used to [microgravity], up is wherever your head is." 

However, for the first couple days in orbit, Morgan described feeling upside down all the time and having no appetite — she ate only soup and drank to stay hydrated, she said in the video. It was not until her fourth day in space that she finally started to feel acclimated to the microgravity environment. 

Fisher, who was the first mother in space, also recalled similar feelings from her time in orbit, including feeling sick the first couple days and just trying to stay oriented. Wherever her feet were was the floor, and whatever was above her was the ceiling, Fisher said in the video. The experience was a "dramatic shift," he added.

Astronauts also tend to experience changes to their taste buds, such that food tastes more bland, so spicier foods are preferred while in orbit. Morgan's favorite space food was the beef stroganoff, while the rest of her crewmates really enjoyed the shrimp cocktail, she said in the video. 

Another difficulty of living in space is the challenge of going to the bathroom in microgravity, which the astronauts compared to sitting on a vacuum cleaner. 

However, the space station recently got an upgrade to its bathroom system. Fischer, who logged 136 days in space with two spacewalks during his 2017 mission to the ISS, works for Collins Aerospace, the company that developed the new toilet system. Called the Universal Waste Management System, it launched to the space station on Sept. 29.

The new space toilet is more efficient, lighter, and smaller than older models. Fischer explained that it is also designed to better accommodate female astronauts and support larger crews for long-duration missions. 

Related: International Space Station at 20: A photo tour

Impacts of long-duration spaceflight 

Building the space station advanced spaceflight by allowing for longer missions.Over the 20-year history of continuous human habitation, NASA has been studying how living in microgravity affects astronauts in preparation for crewed missions to return to the moon and one day travel to Mars or beyond. 

Longer space missions are known to impact the human body in a variety of ways, including triggering changes to astronauts' brain structure and function, vision, heart muscle cells and the diversity of bacteria in the gut. Living and working in microgravity for long periods of time can also cause a loss of bone and muscle mass. 

"We're trying to get better at keeping the human body and the human system working all the way to Mars and back," Fischer said in the video. "On a short-duration [space] shuttle flight, you can probably get away without doing some high impact resistant and resistive exercise, and come back [to Earth] and your bones are still OK. If you do that on a long-duration flight, you'll come back with 20% less bone mass. So we are militant about 2 to 2.5 hours of working out a day, vitamin D supplements and understanding shifts in vision."

Long-duration spaceflight can also be associated with feelings of isolation due to the extended separation from family and friends. Learning to deal with this as astronauts can be applied to current events on Earth, such as the shelter-in-place orders amid the COVID-19 pandemic. 

"It taught me to focus on what was more important to me, opposed to the daily grind," Fischer said. "If you have the constant contact with people and the constant barrage of news and information, you can use it almost as an excuse sometimes not to focus on the things that truly matter." 

You can watch the episode featuring the panel of astronauts online via Viking.TV. 

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