Titles, abstracts and links to talks/presentations given by a member of the LOCSST team can be found bellow.
Author
Christopher B. Mendillo
Title
The PICTURE-C exoplanetary imaging balloon mission: First flight results and second flight preparation - (TALK)
Abstract
The Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph (PICTURE-C) mission will directly image debris disks and exo-zodiacal dust around nearby stars from a high-altitude balloon using a vector vortex coronagraph. The first flight of PICTURE-C launched from the NASA Columbia Scientific Balloon Facility in Ft. Sumner, NM on September 28, 2019 and flew for a total of 20 hours, with 16 hours at float altitude above 110,000 ft. This flight successfully demonstrated many key technologies for exoplanetary direct imaging missions and all hardware components for the second, science-focused flight of PICTURE-C scheduled for the fall of 2021. These technologies include a vector vortex coronagraph, high and low-order deformable mirrors and a high speed low-order wavefront control system. The experiment also demonstrated a 60 cm off-axis telescope with a hexapod-actuated secondary mirror that aligned itself automatically during flight. This paper details the flight performance of PICTURE-C, focusing on the operation of the low-order wavefront control system and the influence of high-frequency structural vibrations. We present new structural modifications that have been made to reduce these vibrations and laboratory demonstrations of the flight #2 coronagraph, which uses a high-order 952 actuator MEMS deformable mirror to create a high-contrast dark zone.
Author
Christopher B. Mendillo
Title
Dual-polarization electric field conjugation and applications for vector vortex coronagraphs - (POSTER)
Abstract
The vector vortex coronagraph (VVC) is a leading choice for future space-based exoplanet direct imaging missions due to its simplicity and high throughput. The construction of the VVC as an azimuthally rotating half-wave plate implies a differential influence on the two orthogonal circular polarization states of incident starlight -- particularly on the mapping of deformable mirror (DM) actuators to the final image plane. Traditional electric field conjugation (EFC) coupled with the VVC is capable of digging a high-contrast dark zone in one circular polarization, but the dark zone is not preserved in the orthogonal state. This paper presents an extension to the traditional EFC algorithm to find DM actuator solutions that produce a dark zone simultaneously in both circular polarizations. This dual-polarization EFC can be used in conjunction with low-leakage VVC architectures to perform high-contrast polarimetric measurements using a single coronagraph.
Author
Kalpa Henadhira Arachchige
Title
Comparing the Performance of a Solar Wind model from the Sun to 1 au using Real and Synthetic Magnetograms
Abstract
We perform a quantitative study which compares the results of the Alfven Wave Solar Atmosphere Model (AWSOM) within the Space Weather Modeling Framework (SWMF). For selected Carrington Rotations, we drive the model by two different solar magnetogram inputs, the observed magnetogram, and a synthetic magnetogram produced by a dynamo model. We simulate the Solar Corona (SC) and the Inner Heliosphere (IH) domains using these SWMF modules. For each case, we compare the observed and simulated cases (real and synthetic magnetogram) using the model synthesized multi-wavelength EUV images. We also extract the simulation data from the IH domain along the earth trajectory to compare with OMNI observational data at 1 au. We initialize the model using the synoptic magnetogram (real magnetogram) and the surface fields maps produced by the dynamo model (synthetic magnetogram) for a set of Carrington rotations within the solar cycle 23 and 24. Our results help to quantify the ability of dynamo models to be used as input to solar wind models, and thus, provide predictions for the solar wind at 1 au.