The ISS will not last forever. That’s why NASA is already working on a gigantic "tug" space

There is nothing written about retirements. There are desired ones, feared ones, postponed ones, there are peaceful ones and there are ones that are out of balance. Few will be comparable, however, with the one faced in a handful of years by the International Space Station —ISS, for its acronym in English—, a unique structure, an example of international collaboration and which received its first crew a whopping 22 years ago, late 2000. And if its story is unique, its end in 2031 will also be unique.

We have known the general idea of ​​what and how his destiny will be for some time. Now, however, NASA has revealed an interesting tidbit: it wants a new “space tug” to help it in the process.

A “space tugboat”? Exact. A few weeks ago the White House federal budget request for 2024 was presented, a more interesting document than it may seem a priori because it includes the amount allocated to NASA: $27.2 billion. Of them there is a small part —small in proportion, of course— of 180 million that is reserved for a showy purpose.

Which? “Start the development of a new space tugboat”, a superficial description that actually hides a ship that intends to help the “retirement” of the ISS, attracting it to the Earth’s atmosphere for its controlled destruction. We know the climax from long time agobut that continues to leave surprises.

Do you know anything else? Not much has been revealed about the project, only the budget figure for fiscal year 2024 and the brushstrokes that NASA itself gave days later during a meeting with the press. One of them points out that the total cost of the ship will be much higher. “We had a cost estimate that was a bit short, around $1 billion,” Kathy Lueders, the space agency’s head of human spaceflight, told reporters.

Its objective is to launch a call to receive proposals and then assess the different options. “We expect to get a better price than that. But this gives us a good start in 24 to get that critical capability on board,” details.

But… What does NASA want it for? Assist in the controlled destruction of the ISS in a few years, when their managers consider their work finished. The objective is what the US agency already detailed in its day: to drag it into the Earth’s atmosphere as part of a controlled re-entry to our planet. The remains that survive that trance will end up falling in the South Pacific.

Will the new ship work alone? No. Faced with such a challenge, a tug can be a valuable ally. At least that’s what NASA thinks. The agency’s plans go through though —details Space.com— for using the vehicle as further mission support. Not the only one. His idea is to complement the resources already available to the different partners on board the space station.

The current plan is to use the engines of the Progress cargo ships, provided by Russia. “We are also developing this United States capability as a way to have redundancy and be able to better assist vehicle orientation and safe return,” explains Lueders. In statements to Gizmodothe directive went even a little further: “Our current model is still used [la nave espacial rusa] and we continue to work with our Russian counterparts on how to safely deorbit Progress vehicles.”

When and how will the goodbye be? At the beginning of 2022 NASA announced that the US government is determined to extend operations on the ISS until 2030. Shortly after the plans transcended from the agency to retire the station in 2031 and thus prevent it from joining the worrying load of space debris that both public agencies and, increasingly, private companies are already dealing with. In its report International Space Station Transition Reportdated January 2022, the agency reveals some important data and dates.

What does the report say? Perhaps one of its most interesting contents is the graph in which, schematically, it presents the planning of the ISS in the last years of its useful life. To be more precise, how its orbit will be altered. His idea is to continue operations, although reducing the altitude from 2026.

The next key moment will come between June and November 2030, when three Progress ships come into play that —accurate New Atlas— will dock with the station and use their engines to slow down. The technicians warn that the calendar could be altered in any case by the solar cycle.

And from that moment on? The ISS will gradually lose altitude until it reaches 280 kilometers, a point of no return. The idea is that once the last engine has burned, it will re-enter the atmosphere in a controlled manner.

The station will break up and the remaining debris will rush into the uninhabited zone of the South Pacific (SPOUA), around “Nemo Point”. “ISS operators will perform the re-entry of the station, giving the final push to lower it as much as possible and ensure a safe entry into the atmosphere,” accurate.

How does the 2022 report describe it? “The ISS will carry out the exit from orbit maneuvers using its propulsion capabilities and those of its visiting ships […]. Not all of them can be used to help in orbit —ditch the dossier—. NASA and its partners evaluated various numbers of Russian Progress spacecraft and determined that three of them can perform deorbit. In addition, Northrop Grumman has been expanding the propulsion capabilities of its Cygnus spacecraft, and NASA has been evaluating whether Cygnus could also be part of the vehicle.”

Images: NASA 1 and NASA 2

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