17.02 Astrophysical Observing Systems
Lead Center: GSFC
Participating Center(s): JPL, LaRC, MSFC
The NASA Space Science Enterprise is studying future missions to explore the Structure
and Evolution of the Universe, which will require very large space observatories. In order
to understand the Structure and Evolution of the Universe, a variety of observatories are
necessary to observe cosmic phenomena from radio waves to the highest energy cosmic
rays. These observatories will peer farther and view objects more fainter than current
Earth-based or space-based observatories and therefore will have increased resolution and
light-gathering ability by greatly increasing the aperture size. It also will be necessary to
operate some of these telescopes at cryogenic temperatures and at a substantial distance
from the Earth. Apertures for normal incidence optics are required in the range of 20 - 40
m in diameter, while grazing incidence optics are required to support apertures up to 10
m in diameter. For some missions, these apertures will form a constellation of telescopes
operating as interferometers. These interferometric observatories will have effective
apertures in the 100 - 1000 m diameter range.
The observatories required for many future SEU missions will also be operated at
cryogenic temperatures (30 K) and at a substantial distance from the Earth. Therefore,
low mass of critical components such as the primary mirror and support and/or
deployment structure is extremely important. It is also essential to develop actuators,
deformable mirrors and other components for operation in a cryogenic environment. In
order to meet the stringent optical alignment and tolerances necessary for a high quality
telescope and to provide a robust design, there are potential significant benefits possible
from employing systems that can adaptively correct for image degrading sources from
inside and outside the spacecraft. This subtopic also includes correction systems for large
aperture space telescopes that require control across the entire wavefront, typically at low
bandwidth. The following technologies are sought:
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Large, ultra-lightweight optical mirrors including membrane optics for very large
aperture space telescopes and interferometers.
Large, ultra-lightweight grazing incidence optics for X-ray mirrors with angular
resolutions less than 5 arcsec.
Ultra-precise, low mass deployable structures to reduce launch volume for largeaperture space telescopes and interferometers.
Segmented optical systems with high-precision controls; active and/or adaptive
mirrors; shape control of deformable telescope mirrors; image stabilization
systems.
Advanced, wavefront sensing and control systems including image based
wavefront sensors.
Shape measurement and control of large aperture membrane optics.
Wavefront correction techniques and optics for large aperture membrane mirrors
and refractors (curved lenses, fresnel lenses, diffractive lenses).
Cryogenic optics, structures, and mechanisms for space telescopes and
interferometers.
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Nanometer and picometer metrology for space telescopes and interferometers.
High-precision pointing and attitude control systems for large space telescopes
and interferometers.
Space-fabricated optics and techniques including fabrication from raw materials
or blanks, coatings, assembly of components, metrology, and system testing.
High-performance materials and fabrication processes for ultra-lightweight, high
performance optics.
Advanced analytical models, simulations, and evaluation techniques and new
integrations of suites of existing software tools allowing a broader and more indepth evaluation of design alternatives and identification of optimum system
parameters including optical, thermal, and structural performance of large space
telescopes and interferometers.
Advanced, low cost, high quality large optics fabrication processes and test
methods including active metrology feedback systems during fabrication, and
artificial intelligence controlled systems.
Technologies for testing new mirror materials and shapes in relevant
environments including cryogenic testing.
New coatings and methods for applying them.
Long path length measurement techniques.
Innovative solutions to detect and correct errors in deployed optical systems.
Deployable optical benches to achieve reference baseline dimensions greater than
those of the payload envelope.
High resolution (2 nm) long stroke (6mm) cryogenic actuators.
Wide field of view optics using square pore slumped micro-channel plates or
equivalent.
Coded masks for 5 mm x 5 mm x 5 mm pixels of high-Z passive metal (Pb or W)
and ~4 m^2 area.
Grazing incidence focusing mirrors with response up to 150 keV.
Develop fabrication techniques for ultra-thin-flat silicon (or like material) for
grating substrates for X-ray energies < 0.5 keV.
Large area thin blocking filters with high efficiency at low energy X-ray energies
(< 600 eV).
Novel optical materials, specialized optical fabrication techniques, and new optical
metrology instruments and components for Earth- and space-based applications are
needed, as follows:
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Develop novel materials and fabrication techniques for producing ultralightweight mirrors, high-performance diamond turned optics, and ultra-smooth
(2-3 angstrom rms) replicated optics that are both rigid and lightweight.
Lightweight silicon carbide optics and structures are also desired.
Develop optics for focusing EUV and X-ray radiation, where reductions in
fabrication time and cost are sought. Developments are also needed in the areas of
surface roughness and figure characterization of EUV and curved X-ray optics,
especially Wolter systems.
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Develop novel materials and fabrication techniques for producing cryogenic
optics. Testing techniques, including both full- and sub-aperture testing, for
cryogenic optics are needed. Also desired are techniques for testing the durability
of and stress in coatings used in harsh environments, particularly cryogenic
optics.
Develop novel techniques for producing and measuring coatings and polarization
control elements. Optical coatings for use in the EUV, UV, visible, IR and far IR
for filters, beamsplitters, polarizers, and reflectors will be considered. Broadband
polarizing- and non-polarizing cube-type beamsplitters are also needed.
Perform development related to fabrication of X-ray, gamma-ray, and neutron
collimators that have the precision necessary to achieve arcsecond or subarcsecond imaging in solar physics and astrophysics when used in stationary
multi-grid arrays or as rotating modulation.
Develop portable and miniaturized state-of-the-art optical characterization
instrumentation and rapid, large-area surface-roughness characterization
techniques are needed. Also, develop calibrated processes for determination of
surface roughness using replicas made from the actual surface. Traceable surface
roughness standards suitable for calibrating profilometers over sub-micron to
millimeter wavelength ranges are needed.
Develop instruments capable of rapidly determining the approximate surface
roughness of an optical surface, allowing modification of process parameters to
improve finish, without the need to remove the optic from the polishing machine.
Techniques for testing the figure of large, convex aspheric surfaces to fractional
wave tolerances in the visible are needed.
Develop efficient, analytical, optical modeling and analysis programs capable of
determining the ground-based and space-based performance of complex aberrated
optical telescopes and instrument systems will be considered. Also, simple, well
documented, flexible programs which generate commands to operate a
numerically controlled polishing machine, given the tool wear profile and surface
error map are desired.
Develop very low scattered light optical material thin film mirror coatings or
mirrors for broad-band white light applications to planet detection space
telescopes.
Develop a novel material for producing doubly curved, ultra-thin, unsupported
shell optical quality telescope mirrors which are capable of being rolled for
storage and transport. These mirrors will exceed one meter in diameter, have an
areal density of < 1.5 kg/m2, and have sufficient "memory" to enable it to return
to its original configuration when unfurled. Fine adjustment will be achieved
using actuator material embedded within the shell mirror or with a two-stage
optics system or both. The reflective surface would not be damaged when the
mirror is rolled. This material must tolerate the space environment without
dimensional changes, stiffness changes, or loss of mechanical integrity.