The ISS celebrates its 25th birthday

On some days, you can see it with the naked eye from Earth: then the International Space Station appears as a bright point moving from west to east across the horizon. For 25 years, humanity's outpost, orbiting the Earth at an altitude of about 400 kilometers at a speed of nearly 29,000 km/h, has been continuously occupied.

On October 31, 2000, a Soyuz spacecraft launched from the Baikonur Cosmodrome in Kazakhstan into Earth orbit. On board were cosmonauts Yuri Gidzenko and Sergei Krikalev, and astronaut William Shepherd. Their destination was the International Space Station (ISS), which sixteen nations had been building since 1998 and which at the time consisted of the Sarja cargo and propulsion module, the Unity connecting node (Node 1), and the Zvezda living module.

On November 2, 2000, the first ISS crew entered the station. Gidzenko, Krikalev, and Shepherd, who stayed on the ISS for over four months, were tasked with setting up the station: unpacking containers, putting the communication system, toilet, and survival systems into operation, and starting the first scientific experiments.

The ISS has since grown to 16 pressurized modules – eight American and six Russian, plus one each from the European Union and Japan. The station's area is roughly equivalent to that of a football field.

The ISS was not the first space station: the Soviet Union launched Salyut 1 in 1971, which remained in space for half a year, from April to October 1971. This was followed by other Salyut stations and, from 1986 to 2001, Mir. The USA launched Skylab into orbit in 1973, which consisted of an unused Saturn rocket stage and was only inhabited from May 1973 to February 1974. Due to a lack of funds, there were no further missions to Skylab until its fiery descent in July 1979.

Spirit of optimism after the end of the Soviet Union

In the spirit of optimism following the collapse of the Eastern Bloc, the idea of a joint space station emerged as humanity's outpost in space. A secondary objective was to keep Russian rocket scientists employed so they would not develop ballistic missiles for other clients.

Despite growing tensions between West and East in the new millennium, the ISS was a successful project for a long time: nearly 300 people from 23 nations had visited by then, including four Germans: Thomas Reiter (2006), Hans Schlegel (2008), Alexander Gerst (2014 and 2018), and Matthias Maurer (2021/22). Several space tourists also visited the station, including Californian millionaire Dennis Tito in 2001 and Ubuntu initiator Mark Shuttleworth the following year.

The station played a role in various feature films, including "Gravity" with Sandra Bullock and George Clooney. However, it only truly served as a filming location once: in 2021, a Russian team filmed there for the movie "The Challenge."

The station is extremely valuable for science: crews have conducted around 4,000 experiments on board. The long-term stays led, for example, to new insights into the human body's reaction to prolonged weightlessness. Lettuce and flowers were grown on the station. Various 3D printers were used to produce parts from plastic or metal, and even artificial tissue.

In its 25 years, the station has witnessed a significant shift in spaceflight: initially, space agencies NASA and Roscosmos were responsible for bringing crews and supplies to the station. Now, at least on the Western side, private companies have taken over these tasks. After the end of the Space Shuttle program in 2011, NASA withdrew and transferred flights to the ISS to space companies, primarily SpaceX.

Unplanned stay on the ISS

This has also led to curious incidents: due to a defect in the spacecraft of the US company Boeing, its crew, consisting of Suni Williams and Barry Wilmore, was stuck on the ISS for nine months. The planned stay was eight days.

Since the Russian invasion of Ukraine in early 2022, relations between the USA and Russia have been strained. The then Roscosmos chief Dmitry Rogozin repeatedly threatened the USA, among other things, with letting the ISS crash. Russia is responsible for maintaining the ISS's orbit and carrying out regular correction maneuvers. However, after some back and forth, both nations agreed to continue cooperation and operation of the ISS.

However, an end is in sight: the ISS mission is expected to end in 2031. The station will then be deorbited in a controlled manner and is expected to burn up upon re-entry into the Earth's atmosphere. SpaceX will carry out the deorbit maneuver.

The end of the ISS will not be the end of humanity's permanent presence in space: China completed the Tiangong ("Heavenly Palace") station in 2022. The West is planning the Lunar Orbital Platform-Gateway station, which will serve as an intermediate station for missions to the Moon and further into space. In addition, some private space companies, like Axiom Space, plan to build stations in orbit.

There will be no anniversary celebration: due to the budget impasse in the USA, federal agencies are largely suspending their work. NASA is therefore closed. Those who want to see the ISS with their own eyes will have the opportunity again at the end of next week.

(wpl)