Orbiting a large number of satellites in fixed formations will be critical to many future space missions, especially large-scale interferometers, telescopes, antennas, and gravity wave detectors. Consequently, extensive research has been devoted over the last 20 years to formation flying architectures, concentrating not only on the mission objective, but also on the technologies required to achieve a stable satellite formation. Several proposals have been suggested for determining the location of the satellites, but the more difficult problem is developing a system that can hold the satellites at those desired locations and orientations. The two most common solutions are to use microthrusters, though these require propellant and will eventually be depleted, or to choose orbital patterns that minimize relative perturbations, but for highly precise positioning, this is not adequate. Neither of these approaches solves the problem for long-duration missions such as a multi-element telescope where the mirrors must be located and oriented to a tolerance less than an optical wavelength.

An approach is described that would allow satellite formation flying to be feasible within a 100-meter volume. This approach provides the feedback forces and torques needed to position and orient a large number of free flying satellites very precisely within the given volume of space by using alternating magnetic fields and synchronous currents.

This approach allows a wide dynamic range of forces, enabling the satellite configuration to be reoriented or reconfigured within a few hours, while still allowing very fine positioning through extremely fine force manipulation. By operating at different frequencies, each satellite can be independently positioned with minimal interaction with its neighbors.

No propellants are required, and the weight of the coils and power requirements are within reasonable ranges. It may be feasible to further reduce the weight and power needed by using superconducting coils.

Finally, the proposed approach is applicable to short-range systems (a few radii distances from the large drive coils), but it is not necessarily appropriate for far-field operation.

This work was done by Robert Youngquist, Stanley Starr, and Mark Nurge of Kennedy Space Center. KSC-13730

NASA Tech Briefs Magazine

This article first appeared in the December, 2014 issue of NASA Tech Briefs Magazine.

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