NanoRacks Bishop Airlock

The NanoRacks Bishop Airlock is a commercially owned and operated module of the International Space Station, forming part of the US Orbital Segment. Launched in December 2020, it represents a meaningful shift in how the station is equipped and used, introducing privately developed infrastructure into what had previously been an exclusively government-built environment. Operated by NanoRacks, a US commercial space company, Bishop has expanded the station's capacity to deploy small satellites, transfer external payloads to orbit, and manage waste disposal. Because it remains permanently attached to the ISS and is not tracked as a separate object, it shares the station's NORAD catalogue identifier 25544 and follows the same orbital path — a roughly circular low Earth orbit inclined at approximately 51.6 degrees, at an altitude of around 408 kilometres.

Purpose and Role

The primary function of the Bishop Airlock is to serve as a transfer point between the pressurised interior of the ISS and the vacuum of space. Airlocks of this kind are essential to any crewed orbital platform: they allow objects and, where applicable, crew members in spacesuits to pass through the station's hull without exposing the inhabited interior to the space environment. Bishop, however, is oriented specifically toward payload operations rather than spacewalks. Its principal uses are the deployment of CubeSats and other small satellites, the external installation of scientific or commercial payloads, and the disposal of materials that cannot be returned to Earth economically.

CubeSat deployment has become one of the most routine and commercially active activities conducted from the ISS. Small satellites built to standardised form factors can be loaded into deployers inside the airlock, transferred outward, and released into orbit, where they gradually drift away from the station and begin independent missions. This capability is used by universities, research institutions, government agencies, and private companies whose projects do not justify a dedicated launch. By expanding the station's throughput for these activities, Bishop allows more such missions to be conducted per year than would otherwise be possible.

The airlock also accommodates larger external payloads — instruments, experiments, or hardware that must be exposed to the space environment directly, whether to collect data, test materials, or perform observations that require an unobstructed field of view. These items can be moved out through Bishop and positioned on the station's exterior by the Canadarm2 robotic arm. The arm plays an indispensable role in Bishop's operations: because the module's bell-shaped geometry and positioning require it to be grappled and manoeuvred, Canadarm2 handles the physical work of extracting and repositioning the airlock's end cone during payload transfer operations.

In addition to its scientific and commercial functions, Bishop provides a practical solution to the ongoing challenge of waste management aboard the station. Certain materials generated during operations are not safe or practical to pack aboard returning cargo vehicles, and in these cases the airlock can be used to eject the waste, which then follows a decaying orbit and burns up on atmospheric re-entry. This is a routine and accepted practice in station operations, governed by established protocols.

Launch and Assembly

Bishop launched on 6 December 2020 aboard a SpaceX Falcon 9 rocket as part of the CRS-21 mission, a commercial resupply flight operated under NASA's Commercial Resupply Services contract. The module rode in the unpressurised trunk section of the Cargo Dragon spacecraft rather than in the pressurised capsule, a configuration suited to hardware that does not require cabin-environment protection during transit and that is destined for external attachment to the station.

After Dragon arrived at the station, Canadarm2 extracted the airlock from the trunk and berthed it to the station's Tranquility node, also known as Node 3. Tranquility is a multipurpose connecting module on the port side of the station's main truss structure and already hosts a number of significant systems and observation facilities. The addition of Bishop to one of Tranquility's ports extended the node's role as a hub of station activity and gave the new airlock a well-connected position in the station's layout, with access to power, data, and thermal control systems.

The integration of a commercially owned module into the ISS structure was not merely a technical milestone but also an administrative one. NanoRacks worked with NASA under existing framework agreements that allow commercial entities to add capabilities to the station, provided those capabilities meet the station's safety and compatibility requirements. The process required close coordination across the organisations involved and set a precedent for future commercial modules that may follow.

Design

Bishop's most visually distinctive feature is its bell-shaped profile, which differs from the cylindrical geometry of most ISS modules. This shape was developed to maximise usable internal volume while fitting within the constraints of the Dragon trunk's available space during launch. The result is a module whose interior offers substantially more room for payload operations than the Kibō Small Fine Arm airlock, which had previously been the primary facility for deploying small satellites from the Japanese Experiment Module. This increased volume allows larger individual payloads to be processed and provides more flexibility in configuring deployer hardware for different mission types.

The airlock operates by isolating a section of internal volume, depressurising it to match the vacuum of space, and then opening an exterior hatch through which payloads are transferred. After the transfer is complete, the hatch closes, the volume is repressurised, and the cycle can begin again. This operational sequence is standard across airlock designs but depends on reliable sealing mechanisms and pressure management systems that must perform consistently across many cycles in the thermal and radiation environment of low Earth orbit.

Because Canadarm2 is required to move the airlock's external structure during operations, the module includes a dedicated grapple fixture compatible with the arm's end effector. This interface is central to the module's function and means that Bishop's operations are scheduled in coordination with other tasks requiring the robotic arm, which remains a shared and carefully managed resource on the station.

Significance and Current Status

Bishop remains attached to the ISS and in operational service. Its continued use reflects both the sustained commercial demand for satellite deployment from the station and the broader direction in which low Earth orbit infrastructure is developing. The module's status as the first commercially owned hardware integrated into the ISS fabric is historically notable: it demonstrates that a private company can not only deliver a service aboard the station but own and operate the physical infrastructure through which that service is provided.

This model has implications for how the station may evolve in its remaining operational years and for how future commercial space stations might be structured. Rather than all infrastructure being procured and owned by government agencies, the Bishop precedent suggests a framework in which commercial operators bring their own assets to orbit, maintain them, and offer access to other users — a structure more analogous to a commercially managed facility than to a government installation.

For satellite tracking purposes, Bishop does not appear as a distinct object in orbital catalogues. It moves with the ISS and is accounted for within the station's overall mass and configuration. Observers tracking NORAD 25544 are therefore tracking Bishop along with the rest of the station. Its orbital parameters at any given time are those of the ISS itself.