Planetary Resources will be putting up hundreds of inexpensive space telescopes with 9 inch mirrors, 2 meter resolution and sub-arcsecond pointing. The passive constellation method for boosting image resolution could achieve centimeter resolution. When Planetary Resources adds some fine station keeping capabilites, they will be able to create massive space telescope interferometers. They will add some starshade satellites and be able to image exoplanets.
Efficient, Passively Orbiting Constellations for High Resolution Imaging of Geosynchronous Objects
Over the past several years, much progress has been made in the development of the Intensity Correlation Imaging approach to ultra-fine resolution imaging. In this paper, we consider the design of a LEO-based observatory of small telescopes using the Intensity Correlation Imaging technology to achieve 1 centimeter resolution imaging of objects in geosynchronous orbit. We formulate the system Modulation Transfer Function (MTF) and then seek to optimize u-v plane coverage by the design of passive, LEO orbits. An adaptive random search technique is used to find constellation designs that offer twice the rate of u-v coverage as earlier results.
Within the context of Intensity Correlation Imaging based on the Brown-Twiss effect, we considered the design of a LEO-based observatory of small telescopes capable of 1 cm resolution imaging of objects in geosynchronous orbit. We formulated the effective system Modulation Transfer Function (MTF) and then sought to optimize u-v plane coverage by the design of passive, LEO orbits. An adaptive random search (ARS) technique was used to find constellation designs that offer twice the rate of u-v coverage as earlier results. The ARS algorithm proved to be an effective approach to obtaining suboptimal but greatly improved solutions to this complex, non-convex optimization problem. This method also offers the flexibility to incorporate additional constraints, such as minimum inter-satellite approach distance. Such extensions are the object of on-going work.
Calculation of Signal-to-Noise Ratio for Image Formation Using Multispectral Intensity Correlation (14 pages)
In previous work, we explored the possibility of using intensity correlation techniques, based upon the Hanbury Brown-Twiss effect to perform fine resolution imaging in the service of exoplanet astronomy. Here we consider a multi-spectral variant of the Hanbury Brown-Twiss technique. At each of a number of independent, light-gathering telescopes photodetection data encompassing each of a set of frequency channels are obtained and then are communicated to some convenient computational station. At the computational station, the correlations among the photodetections in each of the frequency bands are time averaged and then further averaged over the various frequency channels to arrive at measurements of the mutual coherence magnitude for each pair of telescopes. From these statistics, imaging data are, in turn, computed via phase retrieval techniques. Here, within a modern quantum optics framework, we examine the signal-to-noise characteristics of the coherence estimates obtained in this way under a variety of non-ideal conditions. We provide step-by-step derivations of the statistical quantities needed in a largely self-contained treatment. In particular, we examine the effects of partial coherence on a scene typical of exoplanet imaging and show how partial coherence can be used to greatly attenuate the parent star. We find that the multispectral version of intensity interferometry greatly improves the signal-to-noise ratio in general and dramatically so for exoplanet detection. The results also extend the analysis of signal-to-noise to a wider variety of practical conditions and provide the basis for multispectral intensity correlation imaging system design.