Space Systems Design Studio

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LAO Research

Orbit Mechanics

A Lorentz-Augmented Orbit (LAO) depends on a familiar result of Maxwell's equations: a charged particle moving relative to a magnetic field experiences a Lorentz force in a direction perpendicular to both its velocity and the magnetic field. Physicists apply the Lorentz force in the design of particle accelerators. Astronomers see this effect in the unusual celestial mechanics of dust particles in Jupiter's rings.

The Lorentz force can also act on a man-made satellite orbiting within a planetary or stellar magnetosphere if it carries a biased electrical charge. A spacecraft can take advantage of the Lorentz force to achieve propellantless propulsion or follow a non-Keplerian orbit. For examples of LAOs, see the LAO Applications page.

For more information, see:

• Streetman and Peck, "A General Bang-Bang Control Method for Lorentz Augmented Orbits"
• Streetman and Peck, "Gravity-Assist Maneuvers Augmented by the Lorentz Force"
• Streetman and Peck, "New Synchronous Orbits Using the Geomagnetic Lorentz Force"
• Atchison, Streetman, and Peck, "Prospects for Lorentz Augmentation in Jovian Captures"

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Control Strategies

The direction and magnitude of the Lorentz force depends on the directions and magnitudes of the LAO spacecraft's velocity vector and the magnetic field vector at the current location of the spacecraft. Far away from a planetary magnetic field, we may model the field simply as a dipole. However, at orbital altitudes, the field is more complicated. In fact, at an orbital altitude of 400 km, there are eight zones over the Earth each with distinct signs of three magnetic fields components: radial, azimuthal, and latitudinal.

An LAO-capable spacecraft can take advantage of these effects by turning its charge on or off in several of these zones. For example, if the spacecraft charges up in Zones V-VIII and discharges in Zones I-IV, it can perform an inclination change maneuver from 28.5° (the inclination of a vehicle launched from Cape Canaveral) to 0° using propellantless LAO propulsion. Changes to the other orbital elements of the vehicle are also possible.

For more information, see:

• Atchison, Streetman, and Peck, "Prospects for Lorentz Augmentation in Jovian Captures"
• Streetman and Peck, "A General Bang-Bang Control Method for Lorentz Augmented Orbits"

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Spacecraft Architecture

The performance of an LAO spacecraft is governed by its charge-to-mass ratio q/m. A higher value of this ratio allows more extreme orbit modification through the Lorentz force.

Among other technical challenges, an LAO-capable spacecraft must carry a self-capacitive structure to store charge at achievable electrical potential. We have identified several different architectures that offer some prospects for successfully realizing such a spacecraft.

The most promising capacitive structures are those composed of filaments. For instance, a long, cage-like structure can exploit plasma interactions to establish high capacitance for the available potential, and therefore high charge. This wire-cage or "stocking" architecture promises a high ratio of spacecraft charge to mass with reasonable size.

The Microscale Infinite-Impulse Spacecraft project seeks to address these design challenges on a millimeter-scale spacecraft with a charged filament.

For more information, see:

• Streetman and Peck, "A General Bang-Bang Control Method for Lorentz Augmented Orbits"
• Atchison and Peck, "A Millimeter-Scale Lorentz-Propelled Spacecraft"

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