The PICTURE-C balloon mission launched on its second flight from Fort Sumner, NM on September 28, 2022. During this flight, PICTURE-C, which consists of a 60 cm off-axis telescope feeding a vector vortex coronagraph, demonstrated the first high-contrast dark hole from an observatory in a near-space environment. The coronagraph achieved a modest broadband (20%) contrast ratio of 5 x 10-6 , with performance limited by dynamic pointing transients. The low-order wavefront control system achieved optical pointing stabilization of one milliarcseconds RMS for intervals of up to 30 seconds between these transients. This paper will summarize the second flight results and present the development path for PICTURE-D, the next generation direct imaging balloon mission.
The Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph (PICTURE C) is a high-altitude balloon-borne observatory that used a vector vortex coronagraph to image dust and debris disks around nearby stars, as well as develop and test technology necessary for direct imaging of exoplanets from a flight platform. The balloon flight environment presents several challenges: an ambient pressure and temperature of approximately 4 Torr and 220-240 K, combined with significant and varying solar irradiance, lead to time-dependent and anisotropic thermal deformation of the optics and their supporting structure. In order to characterize how these effects limit the ultimate performance of the mission, we present a finite-element model of the flight instrument, implemented in Thermal Desktop, which takes into account the interactions with the environment. We present the comparison of this thermal model with flight data.
The Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph (PICTURE-C) mission is designed to directly image debris disks and exozodiacal dust around nearby stars from a high-altitude balloon using a 60 cm diameter off-axis telescope and a vector vortex coronagraph. During its second flight from Fort Sumner, New Mexico, on September 28, 2022, PICTURE-C successfully used its high and low-order wavefront control systems to perform focal plane wavefront correction for the first time on an observatory in a near-space environment. The coronagraph achieved a modest broadband (20%) contrast of 5 × 10 − 6, with performance limited by dynamic pointing transients. The low-order wavefront control system achieved optical pointing stabilization of 1 milliarcseconds (mas) root mean squared (RMS) over 30 second timescales.
The Planetary Imaging Concept Testbed Using a Recoverable Experiment Coronagraph (PICTURE C) is a high-altitude balloon-borne observatory that uses a vector vortex coronagraph to image debris disks and exo-zodiacal dust around nearby stars. The engineering flight of PICTURE-C launched in September of 2019, successfully demonstrated several key technologies needed for the upcoming science flight, currently scheduled for September of 2022. The flight environment presents several challenges in thermal and mechanical effects. Low ambient pressure and temperature, approximately 4 Torr and 240 K respectively, combined with significant and varying solar irradiance, lead to time-dependent and anisotropic thermal deformation of the optics and their supporting structure. A constantly swaying observatory in a 1g environment, and the mechanical strains of a pointing system keeping the instrument on target lead to both a sag and flexing of the support structure. In order to characterize how these effects limit the ultimate performance of the mission, we present a finite-element model of the flight instrument, implemented in COMSOL, which takes into account the interactions with the environment. We present the comparison of this thermal model with the temperature data available from flight 1.
The Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph (PICTURE-C) mission will directly image debris disks and exozodiacal 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 (CSBF) in Ft. Sumner, NM on September 28, 2019. This flight successfully demonstrated many key technologies for exoplanetary direct imaging missions and all hardware components for the second, sciencefocused flight of PICTURE-C, which had been scheduled for the fall of 2021, but was delayed due to inclement weather until 2022. We present laboratory demonstrations of the flight 2 coronagraph, which uses a high-order 952 actuator MEMS deformable mirror to create a high-contrast dark zone at the 10-7 level. The performance of the low-order and high-order wavefront control systems is demonstrated and compared with model predictions.
The Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph (PICTURE-C) mission will directly image debris disks and exozodiacal 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 ew 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.
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