Starshade optical edge modeling, requirements, and laboratory tests

Stefan R. Martin; Stuart Shaklan; Samuel Crawford; Siu-Chun Lee; Behrouz Khayatian; Daniel Hoppe; Eric Cady; P. Douglas Lisman

doi:10.1117/12.2024188

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26 September 2013 Starshade optical edge modeling, requirements, and laboratory tests

Stefan R. Martin, Stuart Shaklan, Samuel Crawford, Siu-Chun Lee, Behrouz Khayatian, Daniel Hoppe, Eric Cady, P. Douglas Lisman

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Proceedings Volume 8864, Techniques and Instrumentation for Detection of Exoplanets VI; 88641A (2013) https://doi.org/10.1117/12.2024188
Event: SPIE Optical Engineering + Applications, 2013, San Diego, California, United States

Abstract

In conjunction with a space telescope of modest size, a starshade can be used as an external occulter to block light from a target star, enabling the detection of exoplanets in close orbits. Typically, the starshade will be placed some 50,000 km from the telescope and the system oriented so that the sun is on the opposite side of the shade to the telescope, but somewhat away from the line of sight. A small amount of sunlight can scatter from the edges of the shade directly into the telescope. Since the photon rate from an earthlike exoplanet might be only a few photons per minute, it is desirable that the scattered sunlight is also near this level. We have built an analytical model of the performance of starshade edges for both specular and Lambertian surfaces and derived requirements for properties such as reflectivity and radius of curvature. A computer model was also developed to show the appearance of the sunlight from the starshade and assess the contrast with the exoplanet. A commercial electromagnetism code was also used to investigate aspects of the results. We also constructed a scatterometer with which various test edges were measured and derived the likely performance if used in a starshade. We discuss these models and give the principal results.

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Stefan R. Martin, Stuart Shaklan, Samuel Crawford, Siu-Chun Lee, Behrouz Khayatian, Daniel Hoppe, Eric Cady, and P. Douglas Lisman "Starshade optical edge modeling, requirements, and laboratory tests", Proc. SPIE 8864, Techniques and Instrumentation for Detection of Exoplanets VI, 88641A (26 September 2013); https://doi.org/10.1117/12.2024188

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