Wavefront Sensing in Space: Flight Demonstration II of the PICTURE Sounding Rocket Payload

TL;DR

This paper reports on the second flight of the PICTURE sounding rocket, demonstrating active wavefront sensing and control in space with a high-precision deformable mirror, despite flight anomalies, advancing space-based high-contrast imaging technology.

Contribution

It provides the first in-space demonstration of wavefront sensing and deformable mirror actuation for high-contrast imaging in a sounding rocket mission.

Findings

Wavefront sensor achieved median precision of 1.4 nm per pixel.

Deformable mirror with 32×32 actuators was successfully actuated.

System stability median was 3.6 nm per pixel.

Abstract

A NASA sounding rocket for high-contrast imaging with a visible nulling coronagraph, the PICTURE payload, has made two suborbital attempts to observe the warm dust disk inferred around Epsilon Eridani. The first flight in 2011 demonstrated a 5 milliarcsecond fine pointing system in space. The reduced flight data from the second launch, on 25 November 2015, presented herein, demonstrate active sensing of wavefront phase in space. Despite several anomalies in flight, post-facto reduction phase stepping interferometer data provides insight into the wavefront sensing precision and the system stability for a portion of the pupil. These measurements show the actuation of a 32$\times$32-actuator microelectromechanical system deformable mirror. The wavefront sensor reached a median precision of 1.4 nanometers per pixel, with 95% of samples between 0.8 and 12.0 nanometers per pixel. The median system stability, including telescope and coronagraph wavefront errors other than tip, tilt, and piston, was 3.6 nanometers per pixel, with 95% of samples between 1.2 and 23.7 nanometers per pixel.