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Revolutionary low impact docking solution ticks all of the right boxes

16/03/2021

Felix De Wispelaere, Programme Manager

Developing a reliable and resilient berthing and docking solution that offers improved control, faultless capture, and optimum safety was just part of the challenge facing QinetiQ as the European Space Agency’s prime contractor.

Space

A critical requirement was to deliver low impact docking capabilities to maximise flexibility on both cargo and crewed spacecraft as well as heavy and very lightweight vehicles. It was also essential for the new system to be compatible with the new docking ports as defined by the International Docking System Standard (IDSS) as well as the docking ports for the Lunar Gateway Station.

Put simply, it was quite an undertaking! Our work began with a detailed evaluation of current berthing and docking technologies to establish the limitations and operational parameters of existing equipment. This was followed by an exhaustive assessment of new technologies that offered the potential to increase system versatility, control capabilities, and performance. Working in close collaboration with our partners, the design and development programme then began in earnest. This has now culminated with the introduction of the International Berthing and Docking Mechanism (IBDM) – a system that overcomes the limitations of conventional docking systems and sets a new standard for versatility, safety and performance.

A fully computer-controlled solution

The new IBDM uses advanced electronics and a Stewart platform with six coordinated and servo-actuated legs to optimise alignment of the active platform during capture. It provides an autonomous solution with full computer control at both leg level and at platform level and has full fault detection and isolation (FDIR) capabilities. Significantly, the advanced safety features of the system negates any need to interact with vehicle avionics, and the fully configurable active control also enables the IBDM to be used on a large range of different mass vehicles covering both exploratory and resupply missions.

The active control of the Soft Capture System (SCS) enables the platform to minimise the impact loads and to capture even the lightest vehicles, with mechanical latches used to complete soft capture. Structural hooks are used to close and seal the mated interface to confirm hard capture, with a dedicated umbilical feature allowing power and data connectors to be mated between the docked vehicles. The IBDM also employs an integral separation system to provide initial impulse at the time of separation and departure.

We completed extensive testing and evaluation of the IBDM at our dedicated space facilities here in Belgium as well as at the NASA Johnson Space Centre Six-Degree-of-Freedom Dynamic Test System. The revolutionary solution has achieved Technology Readiness Level 6 and demonstrated full compliance with the complete range of IDSS defined masses and inertias and could therefore be demonstrated over the complete flight envelope, with the agile force-sensing controlled capture mode delivering a very high capture success rate.

The induced contact loads during docking with the IBDM are typically one third of the IDSS allowed limit. Such versatility and performance capabilities are, therefore, ideal for docking vehicles with a high equivalent mass like the Dream Chaser Cargo to the International Space Station, as well as more difficult dockings between vehicles with a low equivalent mass such as the Orion to a lunar lander.

QinetiQ just signed a new contract for the supply of four IBDMs to the International Habitat (IHAB), which is the European Space Agency’s contribution to NASA’s Artemis Program. This contract builds upon the IBDM development contract currently in its qualification phase with some specifics for the Lunar Gateway environment. This is just the start of what promises to be a long and enduring story for the IBDM. By putting convention to one side, exploring new ideas and capitalising on new technologies, we have delivered an androgynous low impact solution for docking and berthing large and small spacecraft that offers unprecedented control, safety, reliability and flexibility.