Lightweight Deployable UV/Visible/IR Telescopes Frank Peri, Jr. Earth Science Technology Office NASA Goddard Space Flight Center Michael Hagopian Earth Sciences Directorate NASA Goddard Space Flight Center Mark Lake Composite Technology Development, Inc.

Future remote sensing instruments may need to employ large numbers of frequency-agile instruments capable of multi-scene observations. Real-time, autonomous adaptive sensing and taskability will be critical. Advanced capabilities will include: – Miniaturized observatories – Robust, compact instrument architectures – Large deployable apertures – Aperture synthesis – Miniaturized/programmable components – Low cost manufacturability Technology Enablers to the Vision Key Characteristics

Motivation Programmatic Limiters to the Vision Length of time to plan, development and deploy space-based instruments for periodic focused measurements The result: A decade may pass between the theoretical identification of a phenomenon and the deployment of a space-based asset limits measurement continuity and applicability Limited budgets preclude continually launching unique instruments targeted toward specific measurement needs The result: Instrument designs are targeted to specific measurements and consequently once deployed cannot accommodate new scientific findings

Lightweight Deployable UV/Vis/IR Telescopes Pathway to the Vision Science Needs: Lidar observations for high vertical resolution mapping of tropospheric ozone, CO2, water vapor, NO2, aerosols, and for imaging, and High resolution imaging and spectroscopic observations from high orbits (GEO, LI, and L2)

Lightweight Deployable UV/Vis/IR Telescopes Pathway to the Vision Science NeedsResolution, m Telescope Diameter, m FigureOrbit km/orbit Imaging spectro-radiometer30-100>2.5λ/20GEO, L1, L2 Lidar observation >3.0λ/2500/polar Lidar imager30-300>3.0λ/20500/polar

Lightweight Deployable UV/Vis/IR Telescopes Problems Unique to Earth Observing Measurements Extensive on-going work associated with NGST in deployable telescopes. Unique problems associated with typical Earth observing missions: Thermal cycling effects due to variable solar loading, day/night transitions, thermal shock from going into and out of eclipse and pointing close to Sun line Pointing non inertial reference frame or scene reference complicates attitude control Doppler shifts (wavelength calibration) Orbit maintenance, thruster issues, contamination, control law issues Minimize structural mass with uniform and low CTE across structure with good optical surface Active/adaptive control on Earth scenes (wide dynamic range) Image registration (mapping, land-marking)

Lightweight Deployable UV/Vis/IR Telescopes Problems Unique to Earth Observing Measurements Recent advancements in mirror research have considered the following materials: composite mirrors carbon silicon carbide glass/composite thin meniscus glass beryllium light weighted glass membranes (powered and flat) fresnel lens The fundamental issues associated with these materials are their manufacturability and their subsequent integration into associated control actuators, reaction structures, and deployment systems. Other factors include filter coatings to reduce the heat load on the mirror and the ability to control the mirror in the dynamic thermal environments.

Lightweight Deployable UV/Vis/IR Telescopes Problems Unique to Earth Observing Measurements Structures and mechanisms are also a significant challenge for deployable telescopes. The state of the art is currently: Mid-modulus CFRP, open truss design USAF/RL MISTI (solid hexagonal frame) Multifunctional structures Isogrid vs. solid tubular frame

Lightweight Deployable UV/Vis/IR Telescopes Summary of Technology Approaches Light-weight mirrors –glass/composite –thin film (stretch membrane/replicated shells) Structures and latches –deploy/redeploy capability –elastic memory composite materials Optical alignment techniques –active vs. passive –deformable/correction optics –wavefront sensing/control

Now Array Area (m 2 ) Areal Density (kg/m 2 ) Adaptive Membrane Optics 50m High Resolution Imager GEO High Resolution Thermal Imager Deployable Segmented Telescopes InflatableAntennas Deployable UV/Vis/IR Telescopes Vision-driven Roadmap Key Technologies – Deployable Structures – Multifunctional Structures – Adaptive Control Systems – Membrane Optics and Large Deformable Mirrors Payoff – Enables large diameter instrument front ends – Enables high spatial resolution science Potential Partners – Department of Defense/Energy – NOAA – Academia & Industry – Other U.S. Gov’t Labs

Lightweight Deployable UV/Vis/IR Telescopes Notional Validation Flight In developing a validation test plan to determine what characteristics will be tested, the following elements must be considered: characterization of disturbance sources (e.g., sunshields, reaction wheels, fine-pointing and alignment systems) microdynamic response of mechanically deployable support structures and active control of microdynamics dimensional stability of thin-membrane mirrors and active wavefront correction

UV DIAL : 308/320 10Hz; O 3 vertical resolution km in troposphere; horizontal resolution 100 km; IFOV < 100 m FY Composite Mirror Panels NMP - flight validation Technology Validation Mission Tropospheric Ozone Measurement Capability Salient requirements: 500mJ, 308/320 10Hz Salient requirement: 3m aperture Salient requirements: repeatability reliability, one-time operation Tropospheric Ozone Measurement (UV) Technology Roadmap Precision Latch & Hinge Deployment Mechanisms Diode-pumped Laser Transmitter (UV)

Lightweight Deployable UV/Vis/IR Telescopes Concluding Remarks The science needs established by the vision of NASA’s Earth Science Enterprise challenge the state of the art for instrument technologies. A process by which technology requirements are developed begins by translating the science needs into notional measurement implementations and then defining the critical drivers for achieving the science needs. These drivers result in a set of technology requirements from which development plans can be established. A nominal space validation experiment would include fabrication of a test article of a deployable telescope structure and mating it to a microgravity test platform on the ISS. Tests of micro and macrodynamic characteristics of the structure would be conducted in order to understand and characterize the dynamic responses and deployment of the structure in zero-g. Partnerships between NASA and interagency, international, commercial and academic organizations will be essential to achieve this vision. The economic benefits will be shared across the globe.