A paper presents an algorithm to initialize a formation of N distributed spacecraft in deep space. Such formations will enable variable-baseline interferometers in future NASA missions designed to study the structure and origin of the universe. The algorithm described in the paper reflects some basic assumptions:

  1. Each spacecraft is capable of omnidirectional radio communication with any other spacecraft,
  2. Each spacecraft is equipped with a limited field-of-view sensor relative position sensor (RPS) to measure the relative positions and velocities of other formation members, and
  3. Spacecraft maneuvers must satisfy Sun-angle pointing constraints to shield sensitive optical equipment from direct sunlight.

The formation initialization algorithm proceeds by first dividing the spacecraft into two groups with antiparallel RPS sensor boresights. Next, the spacecraft perform a three-phase (in-plane, out-of-plane, and near-field) sky search involving synchronized maneuvers to ensure full sky coverage while maintaining front-to-front, simultaneous RPS sensor lock. During the sky search, the spacecraft are grouped into two classes of sub-formations. The initialization problem is then reduced to the simpler problem of joining the sub-formations.

The paper includes an analytical proof that the algorithm is guaranteed to initialize the formation as required.

This work was done by Scott Ploen, Daniel Scharf, and Fred Hadaegh of Caltech for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Mechanics/Machinery category.

The software used in this innovation is available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (626) 395-2322. Refer to NPO-43040.

This Brief includes a Technical Support Package (TSP).
Formation-Initialization Algorithm for N Spacecraft

(reference NPO-43040) is currently available for download from the TSP library.

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This article first appeared in the May, 2007 issue of NASA Tech Briefs Magazine.

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