# Presentation: 233010

## 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. |
| --- | --- | --- |

## Technology Enablers to the VisionKey Characteristics

*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***

**Notes:**
Motivation for tech development
“How we do it now” limitation

## 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 Needs | Resolution, m | Telescope Diameter, m | Figure | Orbit km/orbit |
| --- | --- | --- | --- | --- |
| Imaging spectro-radiometer | 30-100 | >2.5 | λ/20 | GEO, L1, L2 |
| Lidar observation | 100-500 | >3.0 | λ/2 | 500/polar |
| Lidar imager | 30-300 | >3.0 | λ/20 | 500/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)*

**Notes:**
Why is EARTH viewing a more difficult problem than some SS stuff!!!

## 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.

**Notes:**
Options in the mirror arena

## 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*

**Notes:**
Composite structure aperture cartoon

## 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*

## Deployable UV/Vis/IR TelescopesVision-driven Roadmap

**Now**

- Array Area (m2)

- 2020

- 2010

- 10

- Areal
- Density
- (kg/m2)

- 1

- 100

- 100

- 1000

- 10000

- 10

- .1

**Adaptive Membrane Optics**

**50m High Resolution Imager**

**GEO High**
**Resolution **
**Thermal Imager**

**Deployable Segmented Telescopes**

**Inflatable**
**Antennas**

**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*

## Tropospheric Ozone Measurement (UV)Technology Roadmap

**UV DIAL**: 	308/320 nm @ 10Hz; O3 vertical resolution 2.0-2.5 km in troposphere; horizontal resolution 100 km; IFOV < 100 m

**Composite Mirror Panels**

- NMP - flight validation

- Technology Validation
- Mission

- Tropospheric Ozone Measurement Capability

- Salient requirements: 500mJ, 308/320 nm @ 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.*