NASA wants SpaceX to dock Dragons at new Russian space station ‘node’

Crew Dragon, meet Prichal. (Mike Hopkins | Anton Shkaplerov)

State media agency RIA says that NASA and Roscosmos are negotiating an agreement that would eventually allow SpaceX Dragon spacecraft and other future visiting vehicles to dock to a new Russian ‘node’ module recently installed on the International Space Station (ISS).

Prichal – Russian for “pier” – was successfully launched into orbit on a Soyuz 2.1 rocket on November 24th. A tug derived from the space agency’s uncrewed Progress resupply ship delivered the decade-old module to the ISS two days later, culminating in a successful docking on November 26th. Weighing almost four tons (3890kg/8600lb), Prichal is a 3.3m (~11ft) wide spherical pressure vessel whose sole purpose is to receive visiting cargo and crew vehicles and (in theory) enable further expansion of the space station’s Russian segment.

It remains to be seen if Roscosmos will be able to complete and launch any of several new planned space station modules in time for doing so to still make sense. Aside from a significant amount of uncertainty as to whether Russia will actually continue to support its ISS segment beyond 2030, Roscosmos has had a nightmarish time preparing the last two “new” segments – Prichal and Nauka. Nauka, a habitation and laboratory module, was originally planned to launch in 2007. Only fourteen years later – in July 2021 – did Roscosmos finally manage to finish and launch the module, which then proceeded to perform a long, uncommanded thruster firing that could have easily damaged or destroyed the entire station on the same day it arrived.

Meanwhile, work on Prichal began in 2007 and the module was initially expected to launch in 2013. Concerted development began in 2010 and construction was completed by 2014. Planned to be an extension of Nauka, Prichal was subsequently forced to spend almost seven years in storage before it was finally brought out of the closet and launched in November 2021.

Now, while odds are firmly against Prichal ever supporting another Russian ISS module, the ‘node’ still has plenty of potential operating solely as a docking hub or (per its namesake) a pier. Outfitted with six docking ports, one of which now connects it to Nauka and the rest of the ISS, the other five ports are effectively free to be used by any arriving Russian spacecraft – including Progress cargo ships, Soyuz crew vehicles, and next-generation Orel (Eagle) spacecraft. However, according to Roscosmos and state media outlet RIA, SpaceX’s Crew and Cargo Dragons and other US spacecraft set to use the western International Docking Adapter (IDA) standard could be added to the list of possible tenants.

To allow a spacecraft fitted with IDA to dock to one of Prichal’s four radial “ASP-GB” ports, some kind of adapter would first need to be designed, constructed, launched, and installed. The specifics of that work are likely what’s being “negotiated” – namely how Roscosmos will be compensated for building its portion of that hypothetical adapter. NASA would likely procure and provide a new IDA port, while Russia would build the ASP-GB connection. As is common for the ISS program, compensation would likely come in the form of services rendered rather than a direct payment, with NASA perhaps launching an extra Russian cosmonaut or providing a larger portion of supplies for a set period.

Some US spacecraft (including Cygnus, Dreamchaser, and SpaceX’s old Dragon) use a common berthing mechanism to mate with the ISS. (NASA)
SpaceX’s new Crew Dragon and Cargo Dragon 2 spacecraft use a different IDA docking adapter and dock autonomously, whereas CBM spacecraft are ‘grappled’ by the station’s robotic Canadarm2 arm. Boeing’s Starliner will also use IDA, as will any other future US crewed spacecraft. (NASA/ESA)

If realized, the addition of a third IDA port at the International Space Station would make life significantly easier for NASA. Even now, with just two spacecraft (Crew and Cargo Dragon) to worry about, NASA is forced to very carefully schedule arrivals and departures and has already had to have SpaceX perform multiple Crew Dragon port relocation maneuvers to prepare for the arrival of other Dragons. In the near future, Boeing’s Starliner spacecraft and semi-annual private Crew Dragon missions to the ISS will also enter the fray, making the scheduling and sequencing of spacecraft arrivals and departures even more challenging.

The US ISS segment really only has two ports still available for conversion to the IDA standard and both are needed to ensure safe, redundant cargo deliveries from uncrewed Cygnus and (as early as next year) Dreamchaser spacecraft throughout the 2020s. Ultimately, that means that an agreement to place a third IDA on the Russian segment is the only clear way NASA can give itself breathing room for the next decade of IDA spacecraft operations.

NASA wants SpaceX to dock Dragons at new Russian space station ‘node’
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