Twenty years of the International Space Station – but was it...

Space scientists are preparing to celebrate a remarkable astronautical achievement. In a few days they will celebrate the 20th anniversary of humanity’s continuous presence in space.

For two decades, astronaut teams have lived 250 miles above our planet by continuously manning the International Space Station (ISS). The ISS was first inhabited on November 2, 2000 by the US astronaut Bill Shepherd and the Russian cosmonauts Sergei Krikalev and Yuri Gidzenko and has since provided protection for a steady rotation of the crews, which ensures that the station never remains unoccupied.

A total of 240 men and women have settled on the 420-ton station, which swept the earth at 27,000 km / h and reaches 16 orbits of our world every day. The accommodation on the 109 meter long station includes six bedrooms, two toilets, a fitness studio – and most importantly a bay window built in Europe called Cupola, which offers a 360-degree view and gives astronauts access to see how storms roll over the earth have accumulated and the sun has risen.

Tim Peake, the only official British astronaut who made it to the ISS, was a particular fan of the dome, where, as he says, he first looked at our planet and realized how fragile it is. “You can see the atmosphere that is only ten miles thick. It’s not endless, ”he recalled in a BBC interview. “All of the gas that keeps us alive on earth is trapped in this tiny layer. You suddenly realize that what we put into this layer is really important. “

Some of the more mundane aspects of station life included guitar serenades from hovering astronauts. a piece of the culinary history of the Italian astronaut Samantha Cristoforetti, who drank the first espresso made in space from a weightless mug; and dealing with a number of broken toilets – “I discovered the part of the station that arouses most curiosity on earth,” says Peake. And these domestic details are important, scientists point out. “The operation of the International Space Station has shown us that people in space, which is a really hostile environment, can move their home away from their own planet,” said astrobiologist Professor Charles Cockell of the University of Edinburgh. “That was an extremely important lesson for us.”

Plans to build a permanent orbiting space station were first drawn up by NASA in the 1980s. However, cost projections indicated that these would be alarmingly high – until the collapse of the Soviet Union offered an opportunity to cooperate with Russia. The space engineers already had considerable experience of long-term space missions with their own small orbiting Salyut stations and the much larger Mir station.

“It was also a very pragmatic move by the United States,” said Professor Anu Ojha, director of the National Space Center in Leicester. “America wanted to prevent Soviet space experts from being apprehended by rogue states when the USSR was dissolved. Therefore, an attempt has been made to include them in a joint space program so that they can stay at home and make some contribution. The ISS was perfect for that. “

In the end, the two nations agreed on a plan for the construction of the ISS, with Canadian and Japanese space agencies, along with the European Space Agency, of which the United Kingdom is a key member, also agreed to join the project. Assembly of the station began in 1998 and required more than 30 US space shuttle flights and 40 Russian missile flights to get components and modules to the station before it was completed in 2011. Astronauts spent years building the station, and only relatively recently, they were able to focus on serious science, including conducting more than 3,000 experiments in collaboration with thousands of scientists on Earth.

The final bill for building the ISS was more than $ 100 billion. The station receives $ 4 billion annually in maintenance costs and service flights. Most of it was paid for by the US. The question is: Was this enormous effort worth it?

Planetology expert Professor Ian Crawford of Birkbeck, University of London, believes this was the case. “The ISS is a fantastic example of high-quality international collaboration at a time when the world desperately needs examples of activities that can bring people and nations together. And when we learn how to live and work in space, we can prepare to return to the moon and possibly send people to Mars. “

However, other scientists take a different stance. “There is no way to justify the enormous sums that have been spent building the ISS,” said royal astronomer Sir Martin Rees. “First of all, the scientific returns have been poor. We learned a little about how the body reacts to long periods of time in space, and we grew a few crystals in zero gravity, but that doesn’t in any way match the tens of billions of dollars spent on the ISS. Really, the station only makes news when its toilets are blocked or an astronaut is singing while floating around with a guitar. “

Nasa’s money would have been better spent on starting robotic missions to other planets or building orbiting observatories, Rees added – a view endorsed by Nobel laureate physicist Steve Weinberg of the University of Texas at Austin. “The only interesting science done on the ISS was studying cosmic rays with the alpha magnetic spectrometer, but astronauts played no part in how it worked,” he said observer. “It could have been put into orbit much cheaper from an unmanned mission.”

Ojha added that he was initially very doubtful about the scientific rationale for the ISS, but was now convinced that it was a great success. “What we have achieved in terms of human space travel experience, space engineering, and scientific output has been immense. We learned how to assemble huge structures in space and live there for a long time while dealing with all sorts of incidents that have occurred. It is vital that we do not waste this experience. “

An important lesson from studying ISS astronauts was the effects of prolonged periods of zero gravity on the human body. These include muscle wasting, reduction in bone density, and impaired vision and taste. Scientists have found that it can take several years for an astronaut to regain bone density after a four or five month space mission. On the other hand, by using treadmills and weight machines, astronauts can avoid the worst effects of muscle wasting.

Nasa is expected to fund the ISS for another four or five years, then hopes private companies will take it over and run it commercially, while the agency funds more cutting-edge missions to explore and settle on the moon, and possibly humans one day to mars. These projects include building Gateway, a smaller version of the space station, in orbit around the moon as a stopover to explore the lunar surface.

But is a private company interested in taking over the ISS? Early interest has been expressed by a number of companies who say they want to work there. Texas-based Axiom Space has signed a contract with NASA to build a module that will be used to research novel materials. Actor Tom Cruise and director Doug Liman are slated to fly to the station in a SpaceX Crew Dragon capsule next year to film scenes for an action-adventure film. and the upcoming reality TV competition, Space hero – scheduled for screening in 2023 – has announced plans to send a winner to the ISS.

Whether such ventures will be enough to provide the billions of dollars needed to operate the station remains to be seen. The alternative would be to disassemble the ISS and send its components spiraling down to Earth in the hopes that if they burned up in the atmosphere they would be destroyed.

And that would be a terrible waste, says Cockell. “It was a hell of a job getting everyone to agree to the station and then building it. We’d have little chance of building another in the near future if we lost this one. So we need to encourage companies to keep the station in operation for at least another decade. “