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Docking Compartment-1 Pirs

Pirs («Пирс», “Pier”) has two roles: as an airlock for spacewalks from the Russian segment, and as a docking port for Soyuz or Progress ships.

It was launched at 23:34:55 UTC on 14 September 2001 on a Soyuz rocket. A specially-modified Progress cargo ship, Progress M-SO1, ferried Pirs to the International Space Station.

Pirs was serve as an interim docking and spacewalk port until the launch of the second FGB or Universal Docking Module. It would then be moved to the azimuth or top port of Zvezda’s Transfer Compartment, to serve as a base for the Science and Power Platform (NEP). The original plan was to discard the module once the better-equipped UDM arrived, but after funding cuts it appeared Pirs would be kept. Even that plan became obsolete with cutbacks to Shuttle launches (the NEP, which was to have been carried up via two Shuttle flights, was cut out of the launch manifest). The 2006 plan sees Pirs moved to the zenith (top) port of Zvezda’s PKhO, Transfer Compartment and still used as an extra docking port for Russian spacecraft.

The DC had a projected lifetime of 5 years, though it looks like this will be extended.

Pirs computer illustration (ESA)

Structure

Pirs has one docking port at either end along its longitudinal axis: one active, the other passive. The active hybrid port, SSVP-M G8000, ССВП-М Г8000 is joined to the nadir port of the Zvezda Service Module. There are electrical connections to transfer power, and hydraulical connections to enable fuel to be transferred from a Progress cargo ship through Pirs to Zvezda’s storage tanks. The passive cone docking point, SSVP G4000, ССВП Г4000, on the opposite end enables Soyuz and Progress ships to dock. It also has fuel and power connection lines.

Pirs is equipped with 4 external antennae to measure relative motion between it and the ISS for its initial docking, and also the Kurs-P system to enable Soyuz and Progress ships to dock automatically to the DC-1.

Inside Pirs are controls for temperature regulation, communications, control of the module, television and telemetry systems and a power supply. There is also a ventilation duct with 3 fans.

The forward half-sphere of Pirs, which has a diameter of 2200 mm, was produced with the same dies and equipment used to construct the forward half-spheres (BO, Orbital Module, бытовой отсек, Bytovoi Otsek) of the Soyuz and Progress ships.

Two manually-operated Strela, «Стрела» (“Arrow”) cargo booms (ГСт-1, GSt-1 & 2) are attached to the base of Pirs (to attachment points BST-1, БСТ-1 & -2) for moving around cargo and cosmonauts. GSt-1 parts were brought up with STS-96 Discovery in 1999 and STS-101 Atlantis in 2000, and attached to the outside of PMA-1 until being retrieved and installed on Pirs in the 8 October 2001 spacewalk. GSt-2 was brought up inside Pirs, and installed during the 14 January 2002 spacewalk.

Pirs takes an hour and 40 minutes to depressurize, and forty minutes to repress. It has two 1000 mm-diameter hatches with windows set in (each 230 mm diameter). Hatch BL-2, БЛ-2 faces between forward and port (planes 2 and 3); BL-1, БЛ-1 faces between starboard and aft (planes 1 and 4). The hatches have annular handrails on the outside and inside.

Each hatch is designed for 120 openings. The hatches open from the inside, ensuring that the atmospheric pressure inside helps keeps them sealed. Unfortunately, some air is lost when a hatch is opened and there is no way of retrieving it (in the U.S. Quest airlock, evacuated air is pumped into retrieval tanks).

Hatch opening

The following hatch opening instructions are taken from yellow stickers (barely) visible in ISS photo ISS004-E-10640, showing Roberto Vittori and Mark Shuttleworth inside Pirs. EV hatch opening:

WARNING: DO NOT OPEN THE EV HATCH IF THE COMPARTMENT PRESSURE EXCEEDS 15mmHG [?].

  1. Hatch tool tab → РАБОЧЕЕ ПОЛОЖЕ НИЕ (working position)
    • √ [check] emergency closure screws are inserted to the hard stop
    • √ handles on hatch rotation → ЗАКР. (closed)
  2. Engage hatch tool on the hatch drive shaft.
  3. Hatch tool → in direction of arrow ОТКР. (open) to the hard stop.
    • √ [?] rollers → ОТКР. (open).
  4. Pusher handle → shut to the hard stop [?]. Move the pusher handle until pressure is equalized.
  5. Open the EV hatch
  6. [?] adjustable [?] and secure it to [?] of Panel 201.
  7. Remove ВЛ-2 [?] (if any)
  8. Report EV hatch opening time (GMT)
  9. Activate Orlan sublimator on exit from DC-1.

EV hatch closing:

  1. Remove the EV hatch frame ring
  2. √ EV hatch interface rubber seals are not damaged
  3. Retrieve the EV hatch from the [?] restraint lock
  4. Move the EV hatch to touch the EV hatchway flange
  5. Rotate the hatch tool in direction of arrow ЗАКР. (closed to the hard stop)
    • √ [?] rollers → ЗАКР. (closed)
  6. Disengage the hatch tool from the hatch drive shaft.

Data tables

Pirs: fundamental technical characteristics
Mass at launch, kg 4350
Mass in orbit, kg 2882
Length of casing, mm 4049
Maximum diameter, mm 4350
Volume of airtight sections, cubic meters 13
Reserve mass for deliverable cargoes 800
Assembly orbit altitude 350-410 km
Working orbit altitude 410-460 km
Length with Docking Assembly extended 2.55 m
Pressurized compartment volume 13 m³
Progress M-SO1 launch data
Designation M-SO1 (№301)
NASA designation 4R
Module designation SO-1 240GK
Launch vehicle Soyuz-U (№677)
Launch date 15 September 2001 at 23:35
Launch site Launch Complex 17P32-5, Area 1, Launch Pad 5, Baikonur Cosmodrome, Republic of Kazakhstan
Docking date 17 September 2001 at 01:05 to the Zvezda SM nadir docking port
Undocking date (MSO-1 Instrument Unit) 26 September 2001 at 15:30
Destruction 26 September 2001 at 23:30
Mission This special variant of the Progress brought the Pirs Docking Compartment-1 module into orbit, along with some supplies, including . The cargo delivered by the vehicle of an overall mass of about 800 kg incorporated such cargoes as flight equipment of Docking Compartment Pirs of about 290 kg (cargo boom, external worksite, portable universal container); science and utilization hardware of about 65 kg including hardware for performance of space experiments and research Plasma Crystal-3, GTS, as well as Andromeda program (to support the Russian-French flight to be performed in October during the ISS visiting crew mission), egress equipment of about 285 kg including spacesuit Orlan-M №14, life support system equipment of about 130 kg, and flight data files
Notes Progress M-SO1 consisted of a standard Progress Instrument Unit and control systems with the Pirs combined docking unit and airlock replacing the usual tanker and orbital modules
Cargo ship Progress MSO-1 (from ЦУП, TsUP)
Mass of ship-module on orbit injection 7130
Mass of Docking Compartment Pirs when fully loaded 3676
Fuel mass in the tanks of the cargo ship 875
Carrier rocket-type Soyuz
Parameters of the working orbit of the ship
• Height to 450 km
• Inclination 51.6°
Duration of flight prior to docking with the Station up to 4 days
Cargo delivered in DC-1 Pirs (from ЦУП, TsUP)
Items Weight (kg)
Regular equipment of docking module, stored in the transport position (Strela cargo boom, working place extension, the universal transfer container) 288.6
Spacewalk equpment (Orlan-M №1280014, oxygen canisters, CO2 absorbent cartridges, water storage containers, universal storage containers) 285.6
Equipment for life support systems 128.4
Equipment for Zvezda SM 13.3
Scientific gear
• For the French program “Andromede” 46.6
• For the “Plasma Crystal-3” experiment 9.2
• For medical studies 6.7
• For the GTS experiment 2.0
Flight documentation 13.4
Total 793.8

Diagrams

Cargo ship-module Progress M-SO1

Pirs diagram
  1. Docking module Pirs
  2. Transitional adapter
  3. Instrumentation/Propulsion Module
  4. Plane of the divided joint
  5. Hybrid active docking assembly SSVP-M
  6. Rod with the television camera
  7. Place of fastening rod with the omnidirectional antennas 2АR-VKA and AR-VKA
  8. Rod with the omnidirectional antennas 2АR-VKA and AR-VKA in the starting position
  9. Rod from the antenna orientation 4AO-VKA in the starting position

(Block with the hydro-steel framework of pumping propellant components is shown without the jacket.) (Diagram via NASA)

The Progress M-SO1 transport ship was a modified version of the Progress M cargo ship. It consisted of the Pirs DC-1 at the front, a transitional adapter and an Instrumentation/Propulsion Module.

The PAO (Instrumentation/Propulsion Module, Priborno-Agregatnyi Otsek, приборно-агрегатный отсек) at the aft end was identical to that of the normal Progress. It contained propulsion fuels and support systems to enable M-SO1 to reach the ISS autonomously.

The transitional adapter connected the PAO with Pirs. Pirs was connected with the adapter via a divided joint which contained 5 pyro-locks and propulsion units. After Pirs docked to the base of Zvezda, the pyro-locks were fired to separate the M-SO1 section from Pirs and deorbit it.

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Photo gallery

Pirs under construction

Pirs under construction at Energiya in Moscow, 2001.

A nadir view of Pirs taken during the STS-108 mission in 2001. Zvezda is towards the top of the photo. Hatch VL-2 is visible, and a Strela crane. (Starboard at left of photo, port to right here as it’s upside-down.)

Mark and Roberto inside Pirs

Roberto Vittori and Mark Shuttleworth inside the Pirs module.