The direct detection and characterization of an Earth-like exoplanet is of the highest scientific priority and a leading technology that will enable such discovery is the starshade external occulter. We report on the latest results in ground-based efforts for demonstrating and advancing the technology of starshades. Using the McMath- Pierce Solar Telescope at the Kitt Peak National Observatory, we are able to track stars as they move across the night sky and stabilize a beam of starlight behind a starshade. This has allowed us to conduct the first astronomical observations achieving high-contrast with starshades. In our latest efforts, we have extended the separation between the starshade and telescope to reach an inner working angle of 10 arcseconds at a flight-like Fresnel number and resolution. In this report, we detail the development of a closed-loop feedback system to further stabilize the beam at the extended baseline and provide results on the contrast achieved. We conclude by laying out future work to design a dedicated siderostat-starshade facility for future testing of and observations with starshades. Our main result: we achieved a broadband contrast ratio of 3:2 x 10-5 at 15 arcseconds IWA, while at a flight-like Fresnel number and resolution.
A novel design of X-ray optical system - concentrator for astrophysical rocket experiment is investigated. The proposed system is
based on four modules with Kirkpatrick-Baez (KB) configuration allowing usage of multi-foil mirrors arranged to parabolic profile.
The KB modules are supplemented by rotationally symmetrical parabolic segments. This X-ray optical system effectively uses
a circular aperture. The KB modules are placed in four quadrants while the segments are set into a Cartesian cross between
the KB modules. Studied optical system is under consideration for the student rocket experiment of University of Colorado that
should verify function of NIST’s energy-dispersive detector based on Transition Edge Sensors (TES microcalorimeters).
We review the progress on the New Worlds Airship project, which has the eventual goal of suborbitally mapping the Alpha Centauri planetary system into the Habitable Zone. This project consists of a telescope viewing a star that is occulted by a starshade suspended from an airship. The starshade suppresses the starlight such that fainter planetary objects near the star are revealed. A visual sensor is used to determine the position of the starshade and keep the telescope within the starshade’s shadow. In the first attempt to demonstrate starshades through astronomical observations, we have built a precision line of sight position indicator and flew it on a Zeppelin in October (2012). Since the airship provider went out of business we have been redesigning the project to use Vertical Takeoff Vertical Landing rockets instead. These Suborbital Reusable Launch Vehicles will serve as a starshade platform and test bed for further development of the visual sensor. We have completed ground tests of starshades on dry lakebeds and have shown excellent contrast. We are now attempting to use starshades on hilltops to occult stars and perform high contrast imaging of outer planetary systems such as the debris disk around Fomalhaut.
In this work, we investigate a novel design of optical system for astrophysics. In addition, a new testing method in the X-ray laboratory was verified. The proposed optical system is composed of modules with Kirkpatrick-Baez configuration allowing usage of multi-foil mirrors arranged to parabolic profile. This system effectively uses a circular aperture, which is divided into petals. Individual petals consist of diagonally oriented KB cells with common focus. The hybrid optical system includes a set of rotationally symmetrical parabolic mirrors to achieve higher reflection efficiency of harder X-rays. New results are presented.
In this work, we investigate a novel design of optical system for astrophysics. In addition, a new
testing method in the X-ray laboratory was verified. The proposed optical system is composed of modules with
Kirkpatrick-Baez configuration allowing usage of multi-foil mirrors arranged along a parabolic profile. This
system effectively uses a circular aperture, which is divided into petals. Individual petals consist of diagonally
oriented KB cells with a common focus. This optical system can be improved by a set of nested rotationally
symmetric X-ray mirrors in order to achieve higher reflection efficiency in harder part of considered spectrum.
We report on preliminary results of full aperture X-ray optical tests at the X-ray test facility at the University
of Colorado (USA) of four test modules of Kirkpatrick-Baez (KB) X-ray optical systems performed in August
2010. Direct experimental comparisons were made between gold-coated optics of two novel substrates: glass
foils and silicon wafers. The preliminary results are promising, with full-width half-maxima of full stacks
being of order of 30 arcsec in 2D full arrangement. These results justify further efforts to improve KB optics
for use in low-cost, high-performance space-borne astronomical imaging instruments for X-ray wavelengths.
CODEX is a sounding rocket payload designed to operate in the soft x-ray (0.1-1.0 kV) regime. The instrument has a
3.25 degree square field of view that uses a one meter long wire grid collimator to create a beam that converges to a line
in the focal plane. Wire grid collimator performance is directly correlated to the geometric accuracy of actual grid
features and their relative locations. Utilizing a strategic combination of manufacturing and assembly techniques, this
design is engineered for precision within the confines of a typical rocket budget. Expected resilience of the collimator
under flight conditions is predicted by mechanical analysis.
We present the CODEX sounding rocket payload, a soft x-ray (0.1-1.0 keV) spectrometer designed to
observe diffuse high-surface brightness astronomical sources. The payload is composed of two modules, each with
a 3.25° x 3.25° field of view defined by a stack of wire grids that block light not coming to a 3.0 m focus and admit
only nearly-collimated light onto an array of 67 diffraction gratings in an off-plane mount. After a 2.0 m throw, the
spectrum is detected by offset large-format gaseous electron multiplier (GEM) detectors. CODEX will target the
Vela supernova remnant later this year to measure the temperature and abundances and to determine the
contributions of various soft x-ray emission mechanisms to the remnant's energy budget; resulting spectra will have
resolution (E/▵E) ranging from 50 to 100 across the band. CODEX is the third-generation of similar payloads from
the University of Colorado, with an increased bandpass, higher throughput, and a more robust mechanical structure
than its predecessors.
We describe the experimental apparatus in use to test an off-plane reflection grating for the
soft x-ray (0.3-1.0 keV) bandpass. The grating is a prototype for the X-ray Grating
Spectrometer on the International X-ray Observatory (IXO). It has holographically-ruled
radial grooves to match the converging beam of a 6.5 m focal length telescope. Laboratory
tests are ongoing, with ray tracing indicating that a resolution (ΔE/E) >3,000 is achievable
across the 0.3-1.0 keV bandpass- the requirement to achieve IXO science goals.
The International X-ray Observatory (IXO) is a collaborative effort between NASA, ESA, and JAXA. The IXO science
goals are heavily based on obtaining high quality X-ray spectra. In order to achieve this goal the science payload will
incorporate an array of gratings for high resolution, high throughput spectroscopy at the lowest X-ray energies, 0.3 - 1.0
keV. The spectrometer will address a number of important astrophysical goals such as studying the dynamics of clusters
of galaxies, determining how elements are created in the explosions of massive stars, and revealing most of the "normal"
matter in the universe which is currently thought to be hidden in hot filaments of gas stretching between galaxies. We
present here a mature design concept for an Off-Plane X-ray Grating Spectrometer (OP-XGS). This XGS concept has
seen recent significant advancements in optical and mechanical design. We present here an analysis of how the baseline
OP-XGS design fulfills the IXO science requirements for the XGS and the optical and mechanical details of this design.
We present results from the Extended X-ray Off-Plane Spectrometer (EXOS) sounding rocket payload. The
payload was launched on November 13, 2009 and successfully obtained a spectrum of the Cygnus Loop Supernova
Remnant. The instrument observed in the ~20 - 110 Angstrom bandpass with high resolution (~50) by utilizing an offplane
reflection grating array. This payload is also the 2nd flight for a relatively new type of detector, the Gaseous
Electron Multiplier (GEM) detector. We discuss the performance of these technologies in flight, as well as an overview
of our plans for the next flight of this design.
We present an overview of the Extended X-ray Off-Plane Spectrometer (EXOS) Sounding Rocket Payload
based at the University of Colorado, Boulder. The program includes a total of four launches over the next four years on
various x-ray sources. The payload utilizes off-plane reflection gratings and Gaseous Electron Multiplier (GEM)
detectors in order to achieve both high throughput and resolution (R~100).
We present the results of the Astrophysics Strategic Mission Concept Study for the New Worlds Observer (NWO). We show that the
use of starshades is the most effective and affordable path to mapping and understanding our neighboring planetary systems, to opening
the search for life outside our solar system, while serving the needs of the greater astronomy community. A starshade-based mission
can be implemented immediately with a near term program of technology demonstration.
We report on progress at the Northrop Grumman Aerospace Systems (NGAS) starshade testbed. The starshade testbed
is a 42.8 m, vacuum chamber designed to replicate the Fresnel number of an equivalent full-scale starshade mission,
namely the flagship New Worlds Observer (NWO) configuration. Subscale starshades manufactured by the NGAS
foundry have shown 10-7 starlight suppression at an equivalent full-mission inner working angle of 85 milliarseconds. In
this paper, we present an overview of the experimental set up, scaling relationships to an equivalent full-scale mission,
and preliminary results from the testbed. We also discuss potential limitations of the current generation of starshades and
improvements for the future.
We present the latest design of an off-plane reflection grating array for the Constellation-X X-ray Grating
Spectrometer. The off-plane design can easily demonstrate the baseline requirements of resolution, R > 1250 and
throughput, effective area > 1000 cm2 from 0.3 - 1.0 keV. Furthermore, the flexibility of the design allows for several
avenues for optimization of these factors. We consider two configurations, 3 m and 9 m from the focal plane using a 20
m focal length telescope. The trade-offs between the two options are discussed.
This paper presents critical engineering aspects of a grating array for a sub-orbital rocket payload to make spectral
observations in the soft X-ray regime. The off-plane grating mount is a natural solution to maximize throughput and
resolution in the 1/4 keV to 1 keV range while minimizing envelope and mass. Replicated radial groove gratings are
matched to the convergence angle of the telescope beam to limit aberrations. These lightweight gratings are mounted
and aligned in an array which is not only efficient for rocket payloads, but can also be made suitable for the X-ray
Grating Spectrometer on Constellation X.
This paper presents analysis showing the sensitivity of the hypergaussian starshade to various types of
errors. These errors are defined and classified. Using a single exemplar of the starshade the sensitivity to
various kinds of errors, the kind now envisioned for the New Worlds Observer mission. After review of
the basics of starshade diffraction, the error classes are defined. The errors include, static errors in global
shape, correlated errors, being the same on all petals, and uncorrelated errors, the errors being unique to
each petal edge. The effects of the first two classes of errors are evaluated using computerized numerical
solutions to the diffraction problem. In the case of uncorrelated errors, a statistical approach is taken.
A new mission concept for direct imaging of exo-solar planets called New Worlds Observer (NWO) has been proposed. It involves flying a meter-class space telescope in formation with a newly-conceived, specially-shaped, deployable star-occulting shade several meters across at a separation of some tens of thousands of kilometers. The telescope would make its observations from behind the starshade in a volume of high suppression of incident irradiance from the star around which planets orbit. For an efficacious mission, the required level of irradiance suppression by the starshade is of order 0.1 to 10 parts per billion in broadband light. We discuss an experiment to accurately measure the irradiance suppression ratio at the null position behind candidate starshade forms to these levels. We also present results of broadband measurements which demonstrated suppression levels of less than 100 parts per billion in air using the Sun as a light source. A simulated spatial irradiance distribution surrounding the null from an analytical model developed for starshades is compared with a photograph of actual irradiance captured in situ behind a candidate starshade.
New Worlds Observer (NWO) is a formation flying mission that combines a starshade with a telescope to study Earthlike
exoplanets around neighboring stars. The general architecture consists of a telescope and detector that share one
spacecraft platform pointed toward a nearby solar system. Planets in the solar system are revealed by blocking the bright
star with a starshade, on its own spacecraft, positioned between the telescope and its target. Questions arise regarding the
type of precision, tolerances, and diffraction control required when considering the practicality of such an endeavor. We
address the generalities here by presenting an overview of requirements necessary for this type of system. Basic
tolerances are described at both the mission and starshade level.
We present laboratory studies of scaled occulting starshades for the New Worlds Observer (NWO). A deep
reactive ion etched silicon starshade has been fabricated by NIST, designed to cover the same number of Fresnel zones
as in the proposed mission. The broadband shadow is mapped with a photometer in a dark vacuum tunnel fed by a
heliostat at HAO. CCD images provide direct contrast measurements of different features around the starshade.
Preliminary measurements reach 5x10-6 suppression in the center of the shadow at the focal plane. The two-dimensional
structure of the starshade diffraction pattern is compared to that produced by the Fresnel integral.
The quest for maximum throughput in high energy astronomy instruments has influenced an increasing trend in spectrograph design toward closely packed mirror and grating arrays. Gratings have additional challenges to those required for mirrors and are evaluated separately in this study. Since these instruments typically operate above earth's atmosphere, grating arrays are subject to a launch vehicle environment. Packing gratings close together in a confined space decreases substrate thickness below traditionally accepted standards for maintenance of surface figure. The everpresent pressure to minimize mass in flight payloads drives substrates even thinner. The University of Colorado has performed a study of several methods that may be employed to make thin gratings. In this paper, some traditional techniques are compared to less conventional ideas for using thin substrates. Environmental effects necessary for flight applications are also folded into the analysis for each thin grating type.
We present a new sounding rocket payload that will perform high resolution (R~100) x-ray spectroscopy of diffuse celestial x-ray sources. The instrument features a new geometry that allows for high resolution along with high throughput. A wire grid collimator constrains light from diffuse sources into a converging beam that feeds an array of diffraction gratings in the extreme off-plane mount. Starting with launch in 2006 we can obtain physical diagnostics of supernova remnants such as the Cygnus Loop and ultimately the hot phase of the interstellar medium.
We present progress in the development of a new sounding rocket payload that will perform high resolution (R~100) x-ray spectroscopy of diffuse celestial x-ray sources. The instrument features a new geometry that allows for high resolution along with high throughput. A wire-grid collimator constrains light from diffuse sources into a converging beam that feeds an array of diffraction gratings in the extreme off-plane mount. Starting with launch in 2006 we can obtain physical diagnostics of supernova remnants such as the Cygnus Loop and ultimately the hot phase of the interstellar medium.
A new sounding rocket payload is being built at the University of Colorado for purposes of resolving spectral features in the diffuse x-ray background. Multiple grating mounts are required; each consisting of over sixty closely packed grazing incidence gratings to meet throughput goals. The rocket skin limits the payload envelope and volume for mounting the gratings. Packing geometries require the gratings be very thin. The gratings are mounted in an off-plane configuration much like a proposed scenario for the Constellation X reflection grating assembly. In this paper we discuss innovative fabrication, replication, and mount techniques used to support a spectral resolution goal of about 100 (λ/δλ).
High groove density reflection gratings placed at grazing incidence in the extreme off-plane mount offer increased performance over conventional in-plane mounts in the x-ray. We are developing an off-plane approach to the Reflection Grating Spectrometer of the Constellation-X Mission. In this paper we discuss the geometry of the off-plane mount and present formulae for the key tolerances of the grating array.
NASA's Strategic Plan for Space Sciences currently envisions a mission capable of resolving the event horizons of supermassive black holes, with imaging-spectroscopy capabilities at angular resolutions better than 0.1 microarcsecond. To achieve this goal, the Micro-Arcsecond X-ray Imaging Mission (MAXIM), a broadband X-ray interferometer, is currently under study. Ground-based proof-of-concept efforts include experiments to demonstrate the feasibility of X-ray interferometry with simple optics. We describe here recent advances in laboratory testbeds, at the University of Colorado and at NASA's Goddard Space Flight Center, that essentially replicate Young's double-slit experiment at X-ray energies. A typical apparatus employs four flat mirrors arranged in periscope pairs, with each pair illuminated at grazing incidence by a slit. We discuss the salient features of these experiments, technical hurdles such as metrology and line-of-sight issues, the successful detection of fringes at wavelengths as short as the Al Kalpha line at 8.35 Angstroms, and future upgrades of our facilities.
The Reflection Grating Spectrometer of the Constellation-X mission has
two strong candidate configurations. The first configuration, the
in-plane grating (IPG), is a set of reflection gratings similar to
those flown on XMM-Newton and has grooves perpendicular to the
direction of incident light. In the second configuration, the
off-plane grating (OPG), the grooves are closer to being parallel to
the incident light, and diffract along a cone. It has advantages of
higher packing density, and higher reflectivity. Confinement of these
gratings to sub-apertures of the optic allow high spectral
resolution. We have developed a raytrace model and analysis technique
for the off-plane grating configuration. Initial estimates indicate
that first order resolving powers in excess of 1000 (defined with
half-energy width) are achievable for sufficiently long wavelengths
(λ ≥ 12Å), provided separate accommodation is made
for gratings in the subaperture region farther from the zeroth order
High groove density reflection gratings placed at grazing incidence in the extreme off-plane mount offer improved performance over conventional in-plane mounts in the x-ray. We present test results from the grating evaluation facility at the University of Colorado for gratings optimized for use in the off-plane configuration. The gratings tested are produce via holographic lithography. Gratings tested have radial groove patterns and include both blazed and sinusoidal groove profiles. We present efficiency and sub-aperture resolution results.
The proposed Micro-Arcsecond X-ray Imaging Mission (MAXIM) uses an array of spacecraft containing grazing incidence optics to create and acquire an image on a distant detector spacecraft. Among the technical challenges facing the mission, maintaining an acceptably small wavefront error in the optical system is addressed in this paper. Starting with a performance model for the observatory and both analytically- and raytrace-based optical sensitivities to misalignment and figure error, an error budget is constructed that includes the effects of the individual optical surfaces, the alignment of the optical elements within the 4-mirror periscope sub-assemblies, and the relative alignment of the many periscopes that make up the MAXIM optical imaging system. At this stage of conceptual development, the allocations to different sub-systems that affect wavefront error is based on the philosophy of "spreading the pain" associated with performance requirements of the contributing elements. The performance model and error budget become tools with which to explore different architectures and requirements allocations as the mission concept develops.
The MicroArcsecond Imaging Mission (MAXIM) will resolve the event horizons of black holes with 0.1 microarcsecond imaging in the X-ray bandpass. In the NASA "Beyond Einstein" roadmap, MAXIM takes it place as the "Black hole Imager." In this paper, we will outline the scientific goals for this mission. We will describe the current state of the technology -- including a discussion of several laboratory demonstrations of X-ray interferometry. We will describe some engineering studies we have performed over the past two years.
The x-ray band of the spectrum is the natural place to perform super-high resolution imaging of astronomical objects. Because x-ray sources can have very intense surface brightness and interferometers can be made with very short baselines, x-ray interferometry has great potential. We will discuss MAXIM, the Micro-Arcsecond X-ray Imaging Mission and, in particular, MAXIM Pathfinder, a coordinated pair of x-ray astronomy missions designed to exploit the potential of x-ray interferometry. We will show how it is possible to achieve huge gains in resolution using today's technology. The Pathfinder mission will achieve resolution of 100 micro-arcseconds and will image the coronae of the nearby stars. MAXIM, with a design specification of 0.1 micro-arcseconds, has the goal of imaging the event horizons of massive black holes. We will explain the architecture of a possible Pathfinder mission and describe the activities NASA is supporting in the area of x-ray interferometry.
This paper discusses X-ray interferometer designs with milli-arcsecond resolution. The goal of this work was to derive interferometer designs that can be built and operated within the budget of a NASA mission. The current interferometer mission designs we propose use separate spacecraft for the optics and detector. Applying design techniques that desensitize the optical performance of the interferometer to spacecraft tip-tilt, and de-center errors was the goal of this work. An interferometer design will be presented with milli-arcsecond resolution. The requirements on relative motion between the spacecraft carrying the interferometer optics and the detector are discussed. Optical performance predictions will be shown.
MAXIM consists of thirty-two individual grazing incidence interferometer channels that act, in combination, like a high-resolution imaging telescope. In this paper, we will describe an optical design for Maxim and calculate principal optical tolerances. These tolerances offer advantages that make anticipated engineering challenges more soluble and affordable within the limitations of current technology. We also discuss key design tradeoffs that contribute to a preliminary tolerance budget.
The MAXIM Pathfinder (MP) mission is under study as a scientific and technical stepping stone for the full MAXIM X-ray interferometry mission. While full MAXIM will resolve the event horizons of black holes with 0.1 microarcsecond imaging, MP will address scientific and technical issues as a 100 microarcsecond imager with some capabilities to resolve microarcsecond structure. We will present the primary science goals of MP. These include resolving stellar coronae, distinguishing between jets and accretion disks in AGN. This paper will also present the baseline design of MP. We will overview the challenging technical requirements and solutions for formation flying, target acquisition, and metrology.
A reflection grating spectrometer featuring off-plane, radial groove gratings for the Constellation-X mission will be presented. Preliminary work shows that off-plane designs can significantly enhance the scientific capabilities of the mission baseline design. Resolutions up to λ/Δλ~5000 can be achieved. The design accomplishes the mission goal for throughput and may also significantly reduce the assembly tolerances. Detailed raytracing and performance assessment of a strawman configuration are included.
The MAXIM (Mico-Arcsecond X-Ray Imaging Mission) and MAXIM Pathfinder, a technology precursor mission, is considered by NASA as 'visionary missions' in space astronomy. Currently the MAXIM mission design would fly multiple spacecraft in formation, each carrying precision optics, to direct x-rays from an astronomical source to collector and imaging spacecrafts. The mission architecture is complex and provides technical challenges in formaiton flying and external metrology, and target acquisition. To further develop the concept, an integrated model (IM) of the MAXIM and MAXIM Pathfinder was developed. Individual subsystem models from disciplines in structural dynamics, optics, controls, signal processing, detector physics and disturbance modelign are seamlessly integrated into one cohesive model to efficiently support system level trades and analysis. The optical system design is a unique combination of optical concepts and therefore results from the IM were extensively compared with ASAP optical software.
The MAXIM Pathfinder (MP) and Stellar Imager (SI) missions are under study to do 100 microarcsecond resolution imaging for a number of different targets using interferometers divided over formation flying spacecrafts. One of the most challenging technical hurdles for these missions is to have an independent directional reference in the sky to use for target acquisition and tracking. This directional reference will guide the placement of separate free flying elements of the interferometers to have ~<30 microarcseconds of alignment with the target. This paper will discuss some of the specific challenges as well as some possible options to explore for achieving this alignment.
The reported optical constants of uranium differ from that of vacuum significantly more than other elements do over the range of about 150 to 350 eV. This suggests that uranium could be used to produce high reflectance imaging mirrors for many soft x-ray applications. Elemental uranium is too chemically active to be used as a front surface mirror without protection. We computed the expected reflectance of carbon-coated uranium films and of uranium-nickel alloys for low-angle reflectors. Carbon is mostly transparent below its K absorption edge at about 283 eV. The reflectance at 10 degrees from grazing is computed to be greater than 50% at 277 eV (C Kα). For comparison, about 5 degrees is the maximum grazing incidence angle for which conventional materials are computed to have comparable reflectance. We sputter deposited and measured the reflectance of carbon-coated uranium layers at 44.7 Å (C Kα). Sample reflectance was a factor of two greater than that of nickel, the material used for low-angle mirrors. The initial oxidation behavior of sputtered uranium-nickel alloys is similar to pure U so their reflectance was not determined. Coatings based on uranium should be considered for all applications where high-reflectance, broadband, low-angle soft x-ray mirrors are required
X-rays have tremendous potential for imaging at the highest angular resolution. The high surface brightness of many x-ray sources will reveal angular scales heretofore thought unreachable. The short wavelengths make instrumentation compact and baselines short. We discuss how practical x-ray interferometers can be built for astronomy using existing technology. We describe the Maxim Pathfinder and Maxim missions which will achieve 100 and 0.1 micro-arcsecond imaging respectively. The science to be tackled with resolution of up to one million times that of HST will be outlined, with emphasis on eventually imaging the event horizon of a black hole.
Our group at the University of Colorado has built a prototype interferometer that demonstrates x-ray fringes. We briefly describe how the instrument works and its geometry, and then present a detailed optical tolerance analysis. Careful analysis shows a grazing incidence design provides enough tolerance relaxation for our x-ray interferometer to work. The challenging nature of x-ray alignment has led us to a methodology that employs a succession of decreasing wavelengths. We also present fringe optimization methods and address environmental conditions that affect stability.
A prototype grazing incidence interferometer has been built and tested at EUV and X-ray wavelengths using a 120 meter long vacuum test facility at Marshall Space Flight Center. We describe the design and construction of the interferometer, the EUV and x-ray sources and detector systems, and compare the interferometric fringe measurements with theoretical predictions.
Grazing incidence mirror parameters and constraints for x- ray interferometry are described. We present interferometer system tolerances used to define mirror surface accuracy requirements. Mirror material, surface figure, roughness, and geometry are evaluated based on analysis results. We also discuss mirror mount design constraints, finite element analysis, environmental issues, and solutions. Challenges associated with quantifying high accuracy mirror surface quality are addressed.
A grazing incidence x-ray interferometer design capable of micro-arcsecond level resolution is discussed. This practical design employs a Michelson Stellar interferometer approach to create x-ray interference fringes without the use of Wolter style optics or diffraction crystals. Design solutions accommodating alignment, vibration, and thermal constraints are reviewed. We present the development and demonstration of a working experiment along with tolerance studies, data analysis, and results.
The far UV spectroscopic explorer grating mechanical design and analysis are discussed. These gratings are large (266 mm X 275 mm), and unique design constraints were imposed to maintain optical performance. FEM results of deflection and stress are presented. Requirements driving the unconventional grating design and its mount are addressed, including the plan to accommodate remote vacuum alignment in multiple degrees of freedom.
Optomechanics intended for flight applications on satellite, rocket, or high altitude balloon payloads have special design requirements in addition to those necessary for earth-based systems. Space environment conditions such as micro-gravity, vacuum, radiation, temperature gradients, and jitter impose special constraints on optomechanical design. Optics and their mounts must not only survive launch loads, but also meet mass and envelope restrictions, maintain precision alignment, and demonstrate long-term stability. Further, these systems must operate remotely once they arrive on-orbit and remain reliable throughout the life of the mission. This course reviews environmental conditions for common orbits, spacecraft, and launch vehicles and describes how they influence optomechanical design requirements. The effect of space conditions on materials is covered in detail. Participants are provided with tools necessary for selecting suitable structural and optical materials, lubricants, and adhesives for flight design. Optomechanical principles appropriate for flight designs are reviewed and methods for resolving common design issues are presented. Flight design examples related to course topics are covered in detail at the end of the day.