There was never any question of the International Space Station (ISS) being forever. His end of career must even be done with a crash, by a final dive into the ocean.
But after more than two decades of cooperation to fly this huge laboratory, Russians and Americans no longer seem to agree on the date of its retirement.
NASA, like the European space agency, repeats that it wants to continue the operation until 2030. But the boss of the space agency Roscosmos announced this week that Russia would withdraw from the program “after 2024”.
The diplomatic tensions caused by theinvasion russe of Ukraine are no strangers to the announcement – even if Moscow had already hinted that it was about to leave.
And between 2024 and 2030 there is now a huge question mark.
First unknown: Russia has not yet said when it was specifically considering abandoning the ship.
A withdrawal as early as 2024 would mean for it a civilian space program grounded, with nowhere to send its cosmonauts. Moscow has announced that it wants to build its own station, but it will not be ready for many years.
Some therefore hope that Russia is working on a later date for its departure from the ISS.
“It is certainly possible to imagine him staying a little longer,” said Scott Pace, director of the Institute for Space Policy at George Washington University, already reassured that Moscow is respecting its prior commitment and does not leave before 2024, as some feared.
Besides the date, the manner also remains to be determined.
Russia has not yet formally notified its desire to withdraw, and many discussions on the transition are expected. They should take place within the framework of the “ multilateral control board », a body bringing together all the partners (United States, Russia, Europe, Japan, Canada).
How far will the Russians go?
Does leaving only mean stopping sending cosmonauts and no longer providing support from the Russian Flight Control Center (TSUP, the equivalent of Houston in the United States)?
Or will they also want to dismantle their segment of the station?
The ISS “isn’t really designed to be dismantled,” said Scott Pace. “It can be, but it’s at least as hard as putting it together. »
According to the expert, a rental agreement could be put in place: the Western partners would pay Russia for the use of its premises – including, importantly, the second and only other toilet in the station.
Such an agreement could interest Moscow, which has lost the income generated by the rental of places on board its Soyuz rockets for NASA astronauts, transported since 2020 by SpaceX.
Technical challenges
Technically, flying the ISS without the Russians or their segment will be difficult, but likely possible.
SpaceX ships can deliver astronauts and supplies (food, fuel, etc.). And Boeing’s capsule, Starliner, should soon offer a second “taxi” to the ISS, with a first manned test planned by the end of the year.
The biggest problem concerns keeping the station in orbit.
It tends to move closer to Earth, and approximately every three months, it has to be “raised” using a propulsion system.
Currently, these thrusts are mainly produced by the engines of the Russian Progress supply vessels moored at the station and, to a lesser extent, by engines located on the Russian module Zvezda.
The beginnings of a solution have recently been sketched out, thanks to a successful test where the altitude of the station was readjusted using the American company Northrop Grumman’s spacecraft, Cygnus. This one, which has been transporting cargo to the station since 2013, has undergone modifications for this purpose.
But its power alone will not be enough, and does not solve another question: that of corrections to the orientation of the station, which must also be prevented from rotating on itself. Such a maneuver requires a second source of propulsion.
SpaceX or Boeing vessels could therefore also be used.
All these efforts must guarantee the future of the ISS until private stations can take over. NASA has already invested in no less than four projects.
Is persisting with so much stubbornness to maintain it until 2030 really necessary? “Perhaps this is not the right strategy for the United States,” argued astronomer Jonathan McDowell. According to him, the Russian withdrawal could also serve as an excuse for Americans to withdraw earlier and invest their money elsewhere. Especially in the return to the moon program.