Micro-Electro-Mechanical Systems (MEMS) Deformable Mirrors (DMs) enable precise wavefront control for optical systems. This technology can be used to meet the extreme wavefront control requirements for high contrast imaging of exoplanets with coronagraph instruments. MEMS DM technology is being demonstrated and developed in preparation for future exoplanet high contrast imaging space telescopes, including the Wide Field Infrared Survey Telescope (WFIRST) mission which supported the development of a 2040 actuator MEMS DM. In this paper, we discuss ground testing results and several projects which demonstrate the operation of MEMS DMs in the space environment. The missions include the Planet Imaging Concept Testbed Using a Recoverable Experiment (PICTURE) sounding rocket (launched 2011), the Planet Imaging Coronagraphic Technology Using a Reconfigurable Experimental Base (PICTURE-B) sounding rocket (launched 2015), the Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph (PICTURE-C) high altitude balloon (expected launch 2019), the High Contrast Imaging Balloon System (HiCIBaS) high altitude balloon (launched 2018), and the Deformable Mirror Demonstration Mission (DeMi) CubeSat mission (expected launch late 2019). We summarize results from the previously flown missions and objectives for the missions that are next on the pad. PICTURE had technical difficulties with the sounding rocket telemetry system. PICTURE-B demonstrated functionality at >100 km altitude after the payload experienced 12-g RMS (Vehicle Level 2) test and sounding rocket launch loads. The PICTURE-C balloon aims to demonstrate ${10}^{-7}$ contrast using a vector vortex coronagraph, image plane wavefront sensor, and a 952 actuator MEMS DM. The HiClBaS flight experienced a DM cabling issue, but the 37-segment hexagonal piston-tip-tilt DM is operational post-flight. The DeMi mission aims to demonstrate wavefront control to a precision of less than 100 nm RMS in space with a 140 actuator MEMS DM.

Accessing the potentially habitable subsurface waters of Ocean Worlds requires a robotic ice probe (or “cryobot”) to traverse tens of kilometers of ice with temperatures ranging from ∼100 to 273 K. Designing and planning such a mission requires understanding ice probe behavior as a function of the local environment and design parameters. We present experimental results of two laboratory melt probes in cryogenic (79 K) and warm (253 K) ice. The melt probe tested in warm ice had multiple adjustable heaters, enabling optimization of the system's efficiency. The melt probes tested in cryogenic ice operated in vacuum and had internal tether spools, allowing for experimental confirmation of hole closure and the creation of a pressurized pocket with liquid water around the probe. These melt probes were tested at power levels ranging from 120 to 1135 W, achieving descent speeds between 5.3 and 59 cm hr⁻¹. By analyzing the relationship between power and speed using analytical and high-fidelity numerical models, we demonstrate progress in understanding melt probe performance. We distinguish between the previously confounding terms of probe operational inefficiency and analytical model inaccuracy, allowing us to understand the range of applicability of the analytical models and demonstrate the importance of controlling heat distribution in cryobot design. The validated models show that while numerical models may be required to describe the behavior of short probes descending in limited-size laboratory test beds, the performance of efficient cryobots designed for operation on Ocean Worlds can be predicted by analytical models within 5% error.

A variety of laser communications, optical sensor, and imaging applications utilize fast steering mirrors (FSM) to execute precision, high speed pointing, and/or angular error rejection as part of closed-loop feedback systems.¹ Traditionally, commercial FSMs have come in two varieties based on their actuation mechanism: piezo electric or voice coil.² Both technologies have heritage with industry-known advantages and disadvantages. Different applications can leverage their strengths while dealing with their weaknesses.²

Data returned from the Cassini–Huygens mission have strengthened Enceladus, a small icy moon of Saturn, as an important target in the search for life in our solar system. Information gathered from Cassini to support this includes the presence of a subsurface liquid water ocean, vapor plumes and ice grains emanating from its south polar region, and the detection of essential elements and organic material that could potentially support life. However, several outstanding questions remain regarding the connectivity of plume material to the ocean and the composition of the complex organic material. Herein we introduce Tiger, a mission concept developed during the 2020 Planetary Science Summer School at NASA’s Jet Propulsion Laboratory. Tiger is a flyby mission that would help further constrain the habitability of Enceladus through two science objectives: (1) determine whether Enceladus’s volatile inventory undergoes synthesis of complex organic species that are evidence for a habitable ocean, and (2) determine whether Enceladus’s plume material is supplied directly from the ocean or if it interfaces with other reservoirs within the ice shell. To address the science goals in a total of eight flybys, Tiger would carry a four-instrument payload, including a mass spectrometer, a single-band ice-penetrating radar, an ultraviolet imaging spectrograph, and an imaging camera. We discuss Tiger's instrument and mission architecture, as well as the trades and challenges associated with a habitability-focused New Frontiers–class flyby mission to Enceladus.

The Deformable Mirror Demonstration Mission (DeMi) payload is an optical instrument that is demonstrating the on-orbit performance of a 140-actuator Microelectromechanical Systems Deformable Mirror (MEMS DM) on a 6U ($10\times 20\times 30{\mathrm{cm}}^3$) CubeSat.^{1 – 6} The key payload requirements are to measure individual DM actuator wavefront displacement contributions to a precision of 12 nm, measure low order optical aberrations to $\lambda /10$ accuracy and $\lambda /50$ precision, and correct both static and dynamic wavefront errors to $<100\mathrm{nm}$ RMS error. The DeMi mission will raise the Technology Readiness Level (TRL) of MEMS DM technology from a five to at least a seven for future space telescope applications⁷ (see the Appendix for a description of NASA TRLs). The DeMi CubeSat began in-space operations in July 2020.

The Deformable Mirror Demonstration Mission (DeMi) is a technology demonstration CubeSat to test a 140 actuator micro-electromechanical system (MEMS) deformable mirror in low-Earth orbit. Such mirrors can provide precise wavefront control with low size, weight, and power per actuator. Hence, they have the potential of improving contrast in coronagraphs on future space telescopes. In the DeMi payload, a Shack Hartmann lenslet array based wavefront sensor monitors the deformable mirror, illuminated by either an internal 636 nm laser diode or external starlight. This work describes the instrument design drivers and CubeSat implementation, and briefly illustrates operation on orbit by comparing ground-based measurements of a displaced actuator to an on-orbit measurement using the internal laser source. The 6U CubeSat was launched on February 25, 2020 and deployed from the International Space Station on July 13, 2020.