Optical and Mechanical Verification of an External Occulter for Starlight Suppression N. Kasdin/Princeton University

In support of NASA's Exoplanet Exploration Program and the Technology Development for Exoplanet Missions (TDEM) opportunity, this proposal, our third in the TDEM program, describes the next essential steps in the technology advancement of an external occulter for starlight suppression. Our First TDEM demonstrated the viability of our petal design and manufacturing approach, showing that a petal can be made with the shaped controlled to an accuracy that meets the requirements for better than 10(-10)contrast. Our second, and current TDEM, will show that our deployment approach meets the requirements on deployed petal positioning. The already-demonstrated petal shape performance,and soon-to-be demonstrated deployment performance, satisfy key elements in technology development for exo-earth detection and characterization. Starshades can image extrasolar earths in the habitable zone without resorting to exotic technologies and placing extraordinary requirements on a space observatory.

For this third TDEM we return to the petal manufacturing and design to demonstrate that the entire petal system is at TRL 5. We propose to again build a full-scale flight-like petal but now including the essential subsystems not considered last time: accommodations for the launch restraint and deployment control, the thermal blanket, and the precision tip section. We will also test a revised design that is stiffer in plane, intended to eliminate the large low frequency bend we discovered in our first experiment. We will also include the sharp flight-like optical edges designed to reduce solar glint, leveraging work done at JPL over the last several years.

Our testing will be more comprehensive as well. We will again perform precision metrology on the petal edges to show that a starshade built to the same accuracy achieves better than 10(-10) contrast, this time before and after several stow and deployment cycles. We will also perform edge scatter tests to demonstrate the efficacy of the new optical edge design. We will perform thermal tests of material coupon samples and petal substructures to verify our thermal modeling. Finally, we will accompany these critical petal system tests with upgraded laboratory optical verification tests at Princeton University to verify the models used to confirm performance.

These combined efforts will bring the critical starshade petal subsystem to TRL 5.

Strategic Astrophysics Technology
Solicitation: NNH12ZDA001N-SAT