Russia announced today that they would be terminating their involvement in the ISS as of 2020, something we guessed would happen. Some news outlets framed this as them just ending their participation, others suggested they'd "kill" the station. The US has been planning on using the station until 2024. Can we do it without them?
This news from Russia is a shame on many levels — even during the worst of the Cold War, the US and the former USSR managed to keep things civil and cooperative in space, starting with the Apollo-Soyuz project of 1975. Now, however, with a new spirit of jackassery permeating the Russian government, Russia is taking its toys and going home.
Currently, some of those Russian toys are pretty important, most notably the tried-and-true Soyuz spacecraft used to ferry astronauts and cosmonauts to the station. The US does have some solutions to replace that, both from NASA and private companies (as well as my terrible ideas), but what about Russia's insistence on stopping their ISS activities? Can the US and European partners in the ISS do without the Russian support and hardware even if we can manage to get astronauts to the station?
I think so. Let's assume that the Russian announcement means the very worst for the station, that the ISS will not be allowed to have any further use of Russian-owned modules and hardware. With that in mind, let's look at exactly what parts of the station the Russian segment comprises.
The Russian segment consists of five modules: Zarya (the first element of the station launched), Zvezda (provides living quarters, a kitchen, and propulsion), Pirs and Poisk, both airlock modules, and Rassvet, a storage/docking module. This collection of modules is known as the Russian Orbital Segment (ROS), and is far less elaborate than originally planned, which included an independent solar array structure and multiple labs. One lab module, Nauka, is planned for launch in 2017, though based on the recent announcement, I'm skeptical the lab module will ever be launched.
So, of these five modules, what is critical to the ISS? The two airlocks and the storage/docking module are completely expendable. While more airlocks and docking modules are absolutely a good thing, the ISS has the Quest airlock on the US side, and there's three PMA (Pressurized Mating Adapters) on the US side to allow for spacecraft docking. One is in use connecting the US side to the Russian side, and the other two are available for visiting spacecraft, like the SpaceX Dragon, and hopefully a crewed version of the Dragon in the near future.
So, if the US is okay as far as docking adapters and airlocks go, what about the other modules? Currently, Zarya isn't really being used for much other than as a hallway and storage. Early on, Zarya provided electrical power and propulsion, but those functions have been largely supplanted by other modules now. Also, Zarya is actually owned by the US, who paid for it's development and launch, so even through it's Russian hardware, we may be able to keep Zarya if the Russians leave.
Zvezda will be a bit trickier, as it provides the main propulsion for the station, as well as the only two private crew berths, a bathroom, and a kitchen/eating/social area. The module design is basically the same as the Mir core module, and this in many ways has always been the heart of the ISS for crew gathering and the like. A lot of the more casual photos taken of the ISS crew are around the table in the Zvezda module, and, personally, it's always been one of my favorite modules. But that doesn't mean it can't be replaced.
In fact, before Zevezda was launched, there were enough questions about whether Russia would be able to get their shit together, financially and otherwise, enough to actually finish it. As a result, a backup propulsion module was designed (actually, more than one) just in case. This propulsion module would have handled the reboost, guidance, navigation, and control functions of the ISS that Zevezda now provides.
With the shuttles gone, the only methods for reboosting the ISS orbit (due to the drag from the very minimal bits of remaning atmosphere in the ISS' orbit, the ISS needs periodic boosts to keep it at the proper orbital altitude) are Zevezda's propulsion system, Progress freighter engines, or the engines on the European cargo ship, the ATV. If the US keeps Zarya, there would still be an ATV-compatible docking port available, allowing a fuel-filled ATV to keep the station boosted until a more suitable control-and-propulsion replacement can be found.
The ISS uses gyroscopes for most of its orientation and attitude adjustments, and those are on the US side, so it's mostly reboots and larger-scale propulsion needs that a new module would have to handle. An expendable-rocket launch-able version of the old backup Propulsion Module could work, and with NASA already having done the development and having a good six years of notice, there should be no reason why one can't be built and made ready for when the Russians leave in 2020.
It seems crazy to scrap the whole station when we've budgeted at least four more years beyond the Russians' deadline. What we should plan on is letting the Russians de-couple their four linked modules (remember, we bought Zarya) from the aft port of Zarya and they can do whatever they want with them. Since Zevezda has a propulsion system, they can take the whole mess and de-orbit it into the ocean if they want, or they could even take it to another orbit and try to use it as the base for a new space station of their own. It's theirs, let them have at it.
In the meantime, we can launch an interim Propulsion Module to dock to the aft port of Zarya, and ideally we can then work on a new, larger habitation/galley/propulsion module to completely replace Zevezda. In fact, it's possible many of these features — the crew quarters and galley— could be incorporated into the very interesting new Bigelow Expandable Activity Module set to launch in 2015.
So, while it saddens me to see politics interfering with space exploration, and while I still believe the Russians do have a special gift for space technology, the truth is we can do just fine without them. Hell, it may even be good for us. Decouple those modules, give 'em a kick away, and never look back.
Fuck 'em. Let's just make it our own station and throw an awesome space party they're not invited to.