Dimitri Rogozin’s incendiary tweetdirector of the Russian Space Agency Roscosmos, about the possibility that the International Space Station (ISS) “falls on Europe” due to Western sanctions on his country, comes to further tense relations with Putin’s Russia. It is understandable that Rogozin has felt forced – like so many others in the government – to align himself with his bellicose president. Question of political survival.
Although cooperation between the Russian agency and its Western counterparts has not been interrupted, the sanctions applied since the invasion of Crimea have posed serious difficulties for the Russian aerospace industry. Now, his reaction rises in tone, alluding to the abandonment of the International Space Station by Russia and its possible fall on inhabited territories.
The ISS is not plummeting; it simply loses height little by little, as a result of the friction of the few gas molecules present even at 400 kilometers high. Therefore, it is necessary to give it an additional boost from time to time to bring it back to its optimal level.
These operations do not follow a program with a fixed date. It depends on how much height the station loses and when. The upper atmosphere expands more or less in response to solar activity and, consequently, its braking effect also varies. Usually, the “push” to the ISS takes place once a month or so.
The ISS has engines to vary its flight height, or simply to move away when there is danger of a collision with another satellite. They are located in the central core of the station, precisely in the Zarya and Zvezda modules, which were the first Russian contribution to the project. There are thrusters placed elsewhere, but only for orientation, not to cause major orbital changes.
In general, all propulsion work on the ISS is the Russian responsibility, including the supply of fuel. About seven tons a year are consumed, an amount that Progress freighters periodically contribute. While they are moored, their own maneuvering engines are usually used to lift the station without the need to resort to those of the ISS. Each ignition can last around 10 minutes and the result is a height gain between 10 and 20 kilometers, although sometimes more.
As an alternative, on some occasions the same operation has been carried out taking advantage of the arrival of a European ATV-type freighter, with more capacity than the Progress and also equipped with its own maneuvering engines. Baptized with the names of characters such as Jules Verne, Kepler, Amaldi, Einstein and Lemaître, only those five flew; the last one, in the summer of 2014. Since then, indeed, the boost maneuvers are only carried out by the Russian capsules. The Space X Dragon is not designed for that task.
NASA intends to keep the station in service until 2030, when it will complete 32 years of service. Then? The truth is that it is not clear what to do with a behemoth of 500 tons and almost 100 meters from side to side. It will probably be forced back into the atmosphere, directing it towards the “dumping ground” in the South Pacific, between New Zealand and Chile. Although the process of falling presents many unknowns and it is not uncommon for some remains to fall on the ground. In the case of the ISS, some pieces (deposits, flywheels, the great chamber for studying cosmic rays…) would surely hit the ground.
What Rogozin is right about is that the fall of the ISS could constitute a danger to others, but not to Russia. In its orbit, inclined 51º, it flies over the entire area between these two parallels, north and south; that is, Central Europe, the entire American continent – from the Canadian border to Tierra del Fuego -, all of Africa, Oceania, Arabia, China, India and Southeast Asia. Russia, whose territory is mostly above 50º north, would not be at risk; Ukraine, yes.
Raphael Clement He is an industrial engineer and was the founder and first director of the Barcelona Science Museum (now CosmoCaixa). He is the author of ‘A small step to [un] man’ (Dome Books).
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