Space Systems Design Studio

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Flux Pinning Applications

Close-Proximity Formation Flight

Environmental forces can cause objects in orbit to drift apart. Flux pinning can augment a multibody system's dynamics by tying the relative motions of disparate components together. The stiffness and damping of the connections are particularly well-suited to act over short distances.

For more information, see:

• Norman, "Stationkeeping and Reconfiguration of a Flux-Pinned Satellite Network"
• Norman and Peck, "Modeling and Properties of a Flux-Pinned Network of Satellites"
• Shoer, "Flux-Pinned Interfaces for the Assembly, Manipulation, and Reconfiguration of Modular Space Systems"

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Non-contacting Mechanisms

Since the flux-pinning effect is based upon changes in magnetic flux through the HTSC volume, any motion that does not change the flux distribution is unaffected by flux pinning. The freedom to design this type of unrestricted motion in a system allows for the creation of non-contacting mechanisms. A system can toggle the number and type of joint degrees of freedom by energizing or deactivating electromagnets. Our research has demonstrated flux-pinned revolute joints (hinges) both on an air table in our laboratory and in a NASA microgravity aircraft program.

A multibody space system with mechanical degrees of freedom will move to a stable equilibrium configuration under the influence of external forces, such as gravity gradient or planetary magnetic fields, and internal forces and torques such as those from reaction wheels or electromagnets. After the system has evolved to equilibrium, toggling the electromagnets in flux-pinned joints will again change the number and type of degrees of freedom, and the system will evolve to a new equilibrium. Careful selection of each set of degrees of freedom in the sequence allows a method of hybrid control that has the potential for very low power consumption and control effort.

For more information, see:

• Shoer and Peck, "Sequences of Passively Stable Dynamic Equilibria for Hybrid Control of Reconfigurable Spacecraft"
• Wilson, Shoer, and Peck, "Demonstration of a Magnetic Locking Flux-Pinned Revolute Joint for Use on CubeSat-Standard Spacecraft"
• Shoer and Peck, "Reconfigurable Spacecraft as Kinematic Mechanisms Based on Flux-Pinning Interactions"
• Shoer, "Flux-Pinned Interfaces for the Assembly, Manipulation, and Reconfiguration of Modular Space Systems"

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Collision Prevention & Actuation

Experimentation indicates that the stiffness of a flux-pinned connection increases approximately exponentially as the separation between the magnetic field source and the HTSC surface decreases. By examining a potential function constructed from these observations, we can define a range of states of the model where collision between the magnetic field source and the HTSC is impossible.

The relative position of the magnetic field source and the HTSC is not the only way to modify the relevant magnetic flux. By tuning the strength of the magnetic field, the flux through the HTSC surface changes, resulting in a change in the properties of the flux-pinned connection. Through this process, we may be able to achieve actuation of pinned interfaces.

For more information, see:

• Norman, "Stationkeeping and Reconfiguration of a Flux-Pinned Satellite Network"
• Shoer, "Flux-Pinned Interfaces for the Assembly, Manipulation, and Reconfiguration of Modular Space Systems"

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Particulate Solar Sails

Traditional solar sail architectures involve large, thin, reflective membranes stretched across lightweight structural elements, a design that has many well-documented engineering challenges.We are proposing an alternative, “fractionated” solar sail in which the sail itself is composed of small discrete particles held in place by superconductive flux-pinning forces.

Not only does a “particulate solar sail” provide a unique solution to the current engineering complexities of solar sailing, it also provides the flexibility and robustness inherent in a discrete fractionated space system. This system could be assembled in multiple launches to take advantage of incremental mission funding and the availability of smaller launch vehicles. Such a system may also lend itself better to in-situ repair missions. Further, a sail made of small independent particles would be highly fault tolerant to both launch-vehicle failures and micrometeoroids. The discrete nature of the particular solar sail’s surface allows small portions to be damaged without affecting the overall performance of the sail, making this sail design especially suitable for proposed missions to asteroids and comets or other small-body rendezvous where the risk of such collisions is high.

For more information, see:

• Jones, "Propsects and Challenges of Particulate Solar Sail Propulsion"

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