[FPSPACE] Station-Keeping Requirements for Constellations of Free-Flying Collectors Used f

[LARRY KLAES]

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

Authors: Ronald J. Allen

(Submitted on 2 Jul 2007)

Abstract: The accuracy requirements on station-keeping for constellations of 
free-flying collectors coupled as (future) imaging arrays in space for 
astrophysics applications are examined. The basic imaging element of these 
arrays is the two-element interferometer. Accurate knowledge of two 
quantities is required: the \textit{projected baseline length}, which is the 
distance between the two interferometer elements projected on the plane 
tranverse to the line of sight to the target; and the \textit{optical path 
difference}, which is the difference in the distances from that transverse 
plane to the beam combiner. ``Rules-of-thumb'' are determined for the 
typical accuracy required on these parameters. The requirement on the 
projected baseline length is a \textit{knowledge} requirement and depends on 
the angular size of the targets of interest; it is generally at a level of 
half a meter for typical stellar targets, decreasing to perhaps a few 
centimeters only for the widest attainable fields of view. The requirement 
on the optical path difference is a \textit{control} requirement and is much 
tighter, depending on the bandwidth of the signal; it is at a level of half 
a wavelength for narrow (few %) signal bands, decreasing to $\approx 0.2 
\lambda$ for the broadest bandwidths expected to be useful. Translation of 
these requirements into engineering requirements on station-keeping accuracy 
depends on the specific details of the collector constellation geometry. 
Several examples are provided to guide future application of the criteria 
presented here. Some implications for the design of such collector 
constellations and for the methods used to transform the information 
acquired into images are discussed.

Comments:  13 pages, 6 figures, accepted 6/29/07 for the August 2007 issue 
of PASP

Subjects:  Astrophysics (astro-ph)

Cite as:  arXiv:0707.0255v1 [astro-ph]

Submission history

From: Ronald J. Allen [view email]

[v1] Mon, 2 Jul 2007 15:38:06 GMT (299kb)

http://arxiv.org/abs/0707.0255