Following the results of Starshade Milestone 1 in which we demonstrated broadband contrast better than 10−10, we have performed model validation experiments to show that diffraction models accurately predict the contrast due to perturbations representing the building blocks of the instrument error budget. The perturbations include the displacement of petal edge segments, sinusoidal petal edge shape deformations, global petal position errors, and random petal radial placement errors. We also show that the model accurately predicts the combined effects of two errors. The experiments result in a measured Model Uncertainty Factor (MUF) that is then applied to the starshade instrument contrast error budget.
Starshades are a leading technology to enable the direct detection and spectroscopic characterization of Earth-like exoplanets. Critical starshade technologies are currently being advanced through the S5 Project and at the Princeton starshade testbed. We report on the conclusion of Milestone 2 of the S5 Project, optical model validation. We present results from optical experiments of starshades with intentional perturbations built into their design. These perturbations are representative of the type of perturbations possible in a flight design and serve as points of validation for diffraction models and error budgets. We show agreement between experiment and diffraction model that meets the Milestone 2 criteria of 25% agreement. We then place these results into the larger context of the design and error budget of a full scale starshade mission. We also present the latest updates to the development of non-scalar diffraction models relevant to the testing of sub-scale starshades. This work completes the optics-focused S5 technology milestones that put starshade technology at TRL 5.
Starshades are a leading technology to detect and characterize Earth-like exoplanets. In this paper we report on optical experiments of sub-scale starshades that advance critical starlight suppression technologies in preparation for the next generation of space telescopes. These experiments were conducted at the Princeton starshade testbed, an 80 m long enclosure testing 1/1000th scale starshades at a flight-like Fresnel number. In this paper we summarize recent updates made to the starshade testbed and optical model. We present results from recent experiments testing two starshade masks with intentional perturbations built into their shape. One of the perturbed masks has three petals that are shifted radially outward by 7-11 microns and the other mask has two petals shifted radially outward plus two petal edge segments displaced from their nominal position. We show the model agrees with experiment to better than 25% accuracy. These results are placed into context with previous experiments on perturbed shapes and progress made towards satisfying a critical milestone in advancing starshade technology to TRL 5.
Starshades are a leading technology to enable the direct detection and spectroscopic characterization of Earth-like exoplanets. Starshade starlight suppression technology is being advanced through sub-scale starshade demonstrations at the Princeton Starshade Testbed and we present here the successful completion of a technology milestone focused on the demonstration of high contrast at flight-required levels. We demonstrate 10-10 contrast at the inner working angle of a starshade with a flight-like Fresnel number at multiple wavelengths spanning a 10% bandpass. We show that while contrast at the inner working angle is limited by the presence of non-scalar diffraction as light propagates through narrow slits between the starshade petals, high contrast is still achieved over most of the image. Successful completion of this milestone verifies we can design a starshade capable of producing scientifically useful contrast levels.
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