English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The accuracy requirements on station-keeping for constellations offree-flying collectors coupled as (future) imaging arrays in space forastrophysics applications are examined. The basic imaging element of thesearrays is the two-element interferometer. Accurate knowledge of two quantitiesis required: the \textit{projected baseline length}, which is the distancebetween the two interferometer elements projected on the plane tranverse to theline of sight to the target; and the \textit{optical path difference}, which isthe difference in the distances from that transverse plane to the beamcombiner. ``Rules-of-thumb'' are determined for the typical accuracy requiredon these parameters. The requirement on the projected baseline length is a\textit{knowledge} requirement and depends on the angular size of the targetsof interest; it is generally at a level of half a meter for typical stellartargets, decreasing to perhaps a few centimeters only for the widest attainablefields of view. The requirement on the optical path difference is a\textit{control} requirement and is much tighter, depending on the bandwidth ofthe signal; it is at a level of half a wavelength for narrow (few %) signalbands, decreasing to $\approx 0.2 \lambda$ for the broadest bandwidths expectedto be useful. Translation of these requirements into engineering requirementson station-keeping accuracy depends on the specific details of the collectorconstellation geometry. Several examples are provided to guide futureapplication of the criteria presented here. Some implications for the design ofsuch collector constellations and for the methods used to transform theinformation acquired into images are discussed.

Station-Keeping Requirements for Constellations of Free-Flying Collectors Used for Astronomical Imaging in Space