20 years of living in space: What's next for the ISS?
Bob McDonald's blog: It's going to come down eventually, so how? And what might replace it?
This week astronauts in space and controllers on the ground celebrated twenty years of continuous occupation of the International Space Station. How much longer will it be useful in light of new plans to return to the moon?
On November 3rd, 2000, the first three-person crew, consisting of two Russian cosmonauts and one American astronaut, launched aboard a Soyuz rocket to the new International Space Station (ISS).
One of the crew, Sergei Krikalev, was also known as the "last Soviet citizen" after he became stranded on the Russian space station Mir when the Soviet Union collapsed in 1991. The first piece of the ISS was based on the Mir design, so he was a logical choice to be among the first to bring the new station to life.
A place in space
Since then, more than 240 voyagers from 19 countries have visited the largest structure ever built in space. With a mass of more than 400 tonnes, the modular structure — with solar panels extended — covers an area larger than a football field, offering an interior living and working volume equal to a Boeing 747 jumbo jet.
While thousands of science experiments have been conducted in the unique environment, the station project hasn't been without criticism.
Compared to the incredible developments of the 1960s that landed humans on the moon in less than a decade, the space station seemed to be a pause in human exploration because all activities were confined to low Earth orbit. Some space exploration advocates, such as engineer Robert Zubrin, founder of the Mars Society, felt we should be heading straight on to Mars.
While the space station didn't take humans to other worlds, it did show what was required to get there, and how to live and work in space for long periods of time.
Just getting to Mars is a six or seven month journey, and the occupants must endure the physical and psychological ravages of space travel. Crew members on the station, especially those who remained for many months, like Canadians Bob Thirsk and Chris Hadfield, and American Scott Kelly — who lived up there for a year — had to exercise daily to prevent muscle atrophy and bone loss. Research on some of the astronauts who made long-duration stays on station found changes in the immune system, even vision problems.
Training ground for further space exploration
The astronauts also learned to get along in a confined space, how to tolerate separation from friends and family, how to grow food and repair equipment — all the skills that will be needed on a journey to Mars and back.
A trip to Mars will be outrageously expensive, likely requiring international cooperation to pull off. The experience of the ISS showed that even former rivals — the U.S. and Russia — can work together. Other participants, like Canadians, Europeans and Japanese, demonstrated that people can thrive in an environment where political boundaries do not exist.
NASA's current focus is returning to the moon by 2024 with the Artemis program. Key to that project is a new space station to be placed in orbit around the moon called Gateway. It too will be an international project, with collaboration from Canada, Europe and Japan. And NASA's somewhat ambitious — and possibly unrealistic — plan is that the first parts of the station will launch by 2024.
Ultimate fate of the ISS
Around that time, decisions will have to be made about the fate of the ISS, which will become a financial burden and may start showing signs of its age after so many years in the hostile environment of space.
One idea is to hand it over to the private sector. A company called Axiom has an agreement to send up modules to attach to the ISS beginning in 2024. They plan to use this as a building block to start constructing their own independent space station that, with the end of the ISS program, they could separate and remain in space as independent laboratories.
But whatever private industry plans, the ISS will eventually reach the end of its useful life, and it will eventually have to be de-orbited, which means driving it down into the atmosphere where it will burn up over the southern Pacific Ocean.
That was the fate of Space Station Mir in 2001 when it was intentionally steered to the most unpopulated area of the planet with none of the debris falling on land. The ISS is twice as big as Mir, so it will be quite a sight streaking across the sky as it re-enters the atmosphere.
One the reasons to de-orbit the station earlier rather than later is the worst case scenario, which would be if something catastrophic happens, like if the station lost its power and needed to be abandoned. In that case it might not be possible to control its orbital decay and re-entry.
No one wants the huge complex to fall out of orbit in an uncontrolled way, because it could end up falling anywhere, including over a city.
The International Space Station did not take humans very far from Earth, but did provide a proving ground where people from many nations were able to learn the lessons about how we will eventually go farther.