• Russia set to launch new docking node to space station

    From NasaSpaceFlight@1337:1/100 to All on Wed Nov 24 10:45:04 2021
    Russia set to launch new docking node to space station

    Wed, 24 Nov 2021 10:40:13 +0000

    Roscosmos is set to launch a new docking node module to the International Space Station The post Russia set to launch new docking node to space station appeared first on NASASpaceFlight.com .

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    Roscosmos is set to launch a new docking node module to the International Space Station (ISS) on Wednesday, November 24 at 13:06 UTC / 8:06 am EST.

    Launching from the Baikonur Cosmodrome in Kazakhstan, the module will add additional docking ports to the Russian Segment of the station to provide options for future expansion.


    The original design for the Russian Segment of the ISS called for a
    Universal Docking Module (UDM) to expand the Russian Segments available docking ports for the addition of future modules. This module was canceled early in the ISS program due to budget issues.

    However, out of the UDM concept grew a new proposal for a Nodal Module (NM), which would provide the Russian Segment with expansion options since all of its docking ports were either in use or reserved for visiting spacecraft.

    The node, named Prichal (pier), marks a departure from the previous concept of Russian station design, which typically included a core module (which, in the case of ISS, is Zvezda) with an attached spherical docking compartment to which all other modules are docked.

    The problem with this design is that it makes the core module an irreplaceable part of the station, as all the other modules would have to be undocked from the core module for the core to be replaced something which is not technically feasible once all modules have been integrated.

    This means that as the core module ages and its systems begin to fail, there is no option but to build a brand-new station, even though the other modules may be newer and perfectly functioning.

    The Node Module concept essentially separates the spherical docking compartment from the core module and makes it into a standalone element. All station modules would then dock to the Node Module, the idea being that each module is then replaceable without having to undock them all.

    In this sense, Prichal is essentially the Russian equivalent of the Node modules found on the US segment of the station.

    It was originally planned that two Science & Power Modules (NEMs) would be docked to Prichal as part of an expansion of the Russian Segment, with a view to then one day separate from the ISS into a free-flying station.

    However, in April 2021, Roscosmos announced that the NEMs are no longer planned for the ISS and will instead form part of a new independent Russian space station for which a new Node Module would be built. Prichal undergoing pre-launch testing at Baikonur. (Credit: Roscosmos)

    While Roscosmos have since somewhat walked back on those statements given
    the budgetary realities of the Russian space program and the remaining lifetime of the ISS, it is unlikely that any additional modules will ever be docked to Prichal.

    Therefore, while Prichal is an interesting module in many ways, it is
    already essentially a module without a purpose as it does not, in itself, add any additional capabilities to the ISS over what the station already has.


    Prichal is a spherical module featuring six docking ports in total two
    axial and four radial.

    The docking ports are of the hybrid type, essentially a combination of the Androgynous Peripheral Attachment System (APAS) and the SSVP probe & drogue system.

    The docking collar itself is the same as the APAS design, but the initial capture is performed using a probe & drogue rather than an extending capture ring. The purpose of the hybrid system is to give a wider hatch passageway
    for larger, permanent modules.

    The zenith docking port of Prichal is an active hybrid port featuring a
    probe to allow it to dock to the ISS. The five remaining ports are passive hybrid ports, featuring drogues to allow other modules to dock to them.

    The nadir docking port of Prichal features a special adapter called SSPA-GM to convert the hybrid docking system into one compatible with the SSVP probe
    & drogue system. This adapter converts the APAS docking collar of the nadir hybrid port into an SSVP docking collar but still uses the same docking
    drogue for initial capture. See Also Prichal UPDATES L2 Russian Section L2
    ISS Section Click here to Join L2

    This will allow Soyuz and Progress vehicles to dock to the nadir port of Prichal, thus maintaining the Russian Segments four docking ports for
    visiting vehicles.

    In the now unlikely event that a new module was to dock to Prichal, this adapter would first have to be removed via a departing Progress spacecraft to convert the nadir port back to a hybrid configuration (with an APAS docking collar) to allow the new module to dock.

    However, this would then render the nadir port of Prichal unusable for Soyuz and Progress dockings, reducing the number of available visiting vehicle
    ports on the Russian side to three.

    Prichal also includes sockets for Lyappa arms. These are mini robotic arms used to relocate modules from one docking port to another, as future modules arriving at Prichal would dock to the nadir port as docking to any of the axial ports would present issues for approach corridors and rotational loads. Via @roscosmos the Prichal docking module (white round thing) on top of a Progress propulsion section (Progress M-UM, the cylinder beneath Prichal) and the Soyuz rocket payload adapter (tapered white section at bottom). Launch to ISS scheduled for Nov 24 pic.twitter.com/UuO4hdogsY

    Jonathan McDowell (@planet4589) November 14, 2021

    The newly arrived module would then relocate itself to an axial port via the Lyappa arm, which would extend from the module and connect to a corresponding socket on Prichal. The Lyappa arm would then rotate and swing the module from the nadir port to the axial port.

    Lyappa arms were used on the Mir space station, and the new Chinese station also features a similar concept . The last time a Lyappa arm was used
    on-orbit was in April 1996 for the post-docking relocation of Mirs Priroda module.

    For launch, Prichal will be attached to a modified propulsion segment of the Progress spacecraft, which will perform all necessary rendezvous and docking maneuvers. The specially modified propulsion segment, named Progress M-UM, is essentially a Progress spacecraft with the pressurized cargo compartment removed and Prichal installed in its place.

    Once Progress M-UM has performed its duty of delivering Prichal to the ISS, it will separate from Prichal and perform a destructive re-entry. This same concept was used to deliver the Pirs and Poisk modules to the ISS in 2001 and 2009, respectively.

    Launch and docking

    Prichal will launch atop a Soyuz 2.1b booster from the Baikonur Cosmodrome
    in Kazakhstan at 13:06 UTC / 8:06 am EST. Following separation from the
    Blok-I stage once in orbit, Prechal will begin a two-day rendezvous with the ISS.

    Assuming Prichal successfully achieves orbit and is declared healthy, the Progress MS-17 spacecraft will undock from the Multipurpose Laboratory Module (MLM) Naukas nadir docking port at 11:18 UTC on Thursday, November 25. A
    Soyuz 2.1b rocket, with Prichal safely inside the payload fairing, is rolled to Site 31/6 at Baikonur for launch. (Credit: Roscosmos)

    The departing Progress will take with it an SSPA-GM Hybrid-to-SSVP docking collar adapter, which is of the same type featured on Prichal.

    This adapter is present on Naukas nadir port, which is of the hybrid type,
    to allow Soyuz and Progress vehicles (which use the SSVP system) to dock there. This was done as an insurance policy in case Prichal fails to achieve orbit.

    Only once Prichal is safely in orbit and on its way to the ISS will the adapter be removed by the departing Progress MS-17, which will convert Naukas nadir port back to hybrid configuration and make it ready to receive Prichal.

    Prichal is planned to dock to the Nauka nadir port on Friday, November 26 at 15:26 UTC / 10:26 EST, using the automated Kurs rendezvous system.

    Following leak checks, hatch opening will be performed in the following
    days. The Progress M-UM propulsion segment is planned to be detached from Prichal on December 21. On January 19, a Russian spacewalk will be performed to connect cables between Nauka and Prichal.

    The first docking to Prichal is planned to take place on March 18, 2022,
    with the Soyuz MS-21 mission.

    (Soyuz stand ready on Site 31/6 at Baikonur for launch of the Prichal module to the ISS. Credit: Roscosmos)

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