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.
13
Embed
Lightweight Deployable UV/Visible/IR Telescopes Frank Peri, Jr. Earth Science Technology Office NASA Goddard Space Flight Center Michael Hagopian Earth.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Lightweight Deployable UV/Visible/IR Telescopes
Frank Peri, Jr.Earth Science
Technology Office
NASA Goddard Space Flight Center
Michael HagopianEarth Sciences Directorate
NASA Goddard Space Flight Center
Mark LakeComposite 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 VisionKey Characteristics
MotivationProgrammatic 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
The result: Instrument designs are targeted to specific measurements and consequently once deployed cannot accommodate new scientific findings
Lightweight Deployable UV/Vis/IR TelescopesPathway 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 TelescopesPathway to the Vision
Science Needs Resolution, m
Telescope Diameter,
m
Figure
Orbit km/orbit
Imaging spectro-radiometer
30-100 >2.5 λ/20GEO, 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 TelescopesProblems 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 TelescopesProblems Unique to Earth Observing MeasurementsRecent 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 TelescopesProblems 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 TelescopesSummary of Technology Approaches
• Light-weight mirrors
– glass/composite– thin film (stretch membrane/replicated shells)
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.