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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Optimizing spectroheliogram deconvolution methods : MaGIXS - A case study

Over the past five years, new methods to reconstruct spectrally pure maps of the Sun from spectroheliogram data have emerged. In particular, with the rebirth of long-abandoned slitless imaging spectroscopy, one may obtain both spatial and spectral information over a large field of view simultaneously. Yet, depending on the size of the extended source combined with the extent of spectral dispersion, there will be locations in the focal plane where spectral lines from different spatial locations overlap and must be deconvolved. An unfolding method has been successfully developed and demonstrated on the recent rocket flight MaGIXS, which observed several strong emission lines (9 to 30$\AA$) from different portions of two active regions. In the work we are going to present, we conduct a systematic investigation of the parameters that controls and optimizes the inversion method to unfold overlappogram data. We also demonstrate a derived method of the inversion that does not require previous assumptions on the thermal and ionization equilibrium and abundance state of the plasma.

Spectroheliogram↗
NASA NTRSDate not supplied

Roman Virtual Lecture Series: History of the Roman Observatory Design, and Current Build Status

- WFIRST (widefield infrared survey telescope, prior mission name) was creation of 2010 NWNH Decadal - Based on JDEM “Omega”, Microlensing Planet Finder, and NIR Surveyor mission concepts - All were three mirror anastigmat near IR staring concepts - JDEM Omega was hardware starting point, but needed to be slightly modified to accommodate continuous viewing periods of the galactic bulge for microlensing - Multiple different surveys rolled into one mission - Imaging, imaging spectroscopy, and precision photometry are all required among the surveys - Cooler than HST optics are required for 2.0um red limit - HST is background limited near room temperature and 1.7um red limit - Mission concepts through 2011 were 1.5m on axis or 1.3m off-axis apertures - 2.4m aperture (NRO transferred to NASA, we were directed to us, in 2012) - Larger primary mirror has 3x area and 0.5x PSF size, ~20x discovery potential - Realized best design has undersampled PSF with survey strategy to recover full sampling, best compromise of sampling vs wide area coverage - Concept evolved significantly with our understanding of the existing optics - Started with “use as is”; evolved over time towards current concept - Overall design has been very stable after early evolution described here - Renamed in 2020 after Nancy Grace Roman; progressing toward launch readiness in Oct2026

Roman Space Telescope↗
NASA NTRS2024

SCIFLI HORIS Windowpane Optical Analysis

This NASA Technical Memorandum summarizes windowpane optical analyses for the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification and Security Regolith Explorer) mission [1] supported by the SCIFLI (Scientifically Calibrated In-Flight Imagery) team [2] at NASA Langley Research Center (NASA LaRC). The SCIFLI team led a NASA multi-center team in characterization of fused silica (FS) and anti-reflective coated (AR-coated) sapphire materials for use as aircraft windowpanes. These materials were needed for the Hypervelocity OSIRIS-REx Reentry Imaging & Spectroscopy (HORIS) mission and were tested to generate performance parameters relevant to the flight environment. Some of the assessed parameters included optical quality, transmittance, reflectance, color balance, birefringence, transmitted wavefront error, wedge, and haziness of the windows. In order to evaluate the material characteristics in a uniform manner, several criteria were held constant. For example, the physical dimensions of the test articles were held constant (i.e., 17-inch diameter aircraft windowpane and 2-inch diameter witness samples). In this way, the comparison of test results from one material specimen to another was invariant with regard to the manner in which the tests were conducted. This also reduced the variability in how the data were reported. As a result, the results shown in this report, including test data generated by NASA can be used for windowpane material evaluation and future material design trades. Window designers can use the data and the testing method along with the testing matrices to efficiently match material performance to their design and mission objectives and requirements. Standardized testing methodologies and data reduction procedures are described in this report. Unless otherwise noted in the data itself, all the windowpane materials were tested in order to characterize their performance for the HORIS mission. One appendix has been included in this report. These include detailed wavefront interferograms of transmitted wavefront error and optical wedge used in the generation of aggregated material performance.

SCIFLI↗
NASA NTRS2026

Global Model Estimates of Atmospheric Al, Ca, Fe, Si, and Ti from Dust and Non-Dust Aerosols Informed by EMIT Surface Mineralogy and Evaluated Against Observations

Atmospheric deposition of micro-nutrients like Fe has been shown to be important for ocean biogeochemistry. The largest source of atmospheric Fe and other elements (e.g., Ca, Al, Si, and Ti) is desert dust, although there are significant non-dust sources in some regions. However, past estimates of these elements have been substantially uncertain due to limited information about the composition of the desert source regions. Here we use elemental distributions estimated from new Earth Surface Mineral Dust Source Investigation (EMIT) observations, which provide mineralogical composition at the surface of the Earth based on imaging spectroscopy measurements from the International Space Station. We add in other sources of these elements (anthropogenic and natural) and compare to a compilation of available surface concentration data from stations over land and from shipborne observations. Our results suggest that the modeled distribution is similar to available observations, but discrepancies still exist in both natural desert dust regions as well as regions dominated by anthropogenic sources. Global budgets for the elements Ca, Al, Fe, Si, and Ti suggest that desert dust remains the dominant source for these elements but anthropogenic or volcanic sources are also important for these elements. Changes in elemental distributions since preindustrial times were also estimated.

aerosols↗
NASA NTRS1987

Imaging and nondispersive spectroscopy of soft X rays using a laboratory X-ray charge-coupled-device system

This paper describes the design and performance of a laboratory instrument for imaging and nondispersive spectroscopy of soft X-rays (300 eV to 10 keV) utilizing a virtual-phase CCD. This instrument has achieved a spatial resolution of 22 microns (limited by pixel size) with an overall array area of 584 x 390 pixels. It has achieved an energy resolution of about 140 eV FWHM for single-pixel Fe-55 X-ray events (5.9 keV) with the CCD operated at -30 C. The CCD has been operated in photon-counting mode at room temperature, and X-ray spectra with an energy resolution of about 450 eV at 5.9 keV have been obtained. The low energy X-ray sensitivity of the CCD also has been demonstrated by detecting carbon K-alpha X-rays (277eV).

Luppino, Gerard A.↗
NASA NTRS2023

The Earth in Living Color - NASA’s Surface Biology and Geology Designated Observable

The Surface Biology and Geology (SBG) Designated Observable will transform our understanding of the global land surface, inland and coastal aquatic ecosystems through visible-to-shortwave infra-red imaging (VSWIR) spectroscopy and thermal infra-red (TIR) imaging. SBG is one of four high-priority observables recommended in the 2017 NASA Earth Science Decadal Survey t o address science questions on vegetation and aquatic ecosystem health, snow-cover dynamics, volcanic activity, and minerology. With a planned launch readiness date of 2028, SBG is currently in Pre-Phase A, with Level 1 requirements being developed for a two-spacecraft architecture, including an additional constellation pathfinder. The recommended architecture emerged from an extensive study (2018-2021) that engaged the research and applications community to consider the science questions and measurement objectives of the Decadal Survey. A Science and Applications Traceability Matrix was used as a basis for scoring candidate architectures, with inputs from four working groups that covered algorithms, applications, calibration and validation, and modeling. Two pathfinder studies, Modeling End-to-End Traceability in support of SBG (MEET-SBG) and Space-based Imaging Spectroscopy and Thermal pathfindER (SISTER) are providing pre-launch modeling tools and data for algorithm development to support science value trades. The architecture consists of one spacecraft hosting a wide-swath VSWIR imaging spectrometer providing 30-m ground-sample distance (GSD), a spectral range of 380-2500 nm (at 10 nm resolution), 16-day revisit with 400 signal-to-noise for VNIR and 250 for SWIR (at 25% reflectance). A separate spacecraft will host a wide swath thermal imager, with five to seven bands placed between 4-12 μm), with 60-m (GSD), 3- day revisit, and 0.2K noise-equivalent differential temperature (NeDT). A VNIR compact camera will be hosted on the TIR spacecraft to enable coincident TIR and VNIR observations. A constellation pathfinder will evaluate options for enabling VSWIR mission continuity using Small Sats or data buys. Partnerships with international space agencies contribute technology as well as improvements to temporal revisit. SBG, when launched, will be the first dedicated mission collecting the full spectra of the Earth’s ‘living color’ and will play a critical role in NASA’s Earth System Observatory.

David S Schimel↗
NASA NTRS2008

The James Webb Space Telescope and its Potential for Exoplanet Science

The James Webb Space Telescope (JWST) is a large aperture (6.5 meter), cryogenic space telescope with a suite of near and mid-infrared instruments covering the wavelength range of 0.6 microns to 28 microns. JWST s primary science goal is to detect and characterize the first galaxies. It will also study the assembly of galaxies, star formation, and the formation of evolution of planetary systems. Recent progress in hardware development for the observatory will be presented, including a discussion of the status of JWST s optical system and Beryllium mirror fabrication, progress with sunshield prototypes, and recent changes in the integration and test configuration. We also review the expected scientific performance of the observatory for observations of exosolar planets by means of transit imaging and spectroscopy and direct imaging. We also review the recent discovery of Fomalhaut B and implications for debris disk imaging nd exoplanet detection with JWST.

Clampin, Mark↗
NASA NTRS2003

New RHESSI Results on Particle Acceleration and Energy Release in Solar Flares

The primary scientific objective of NASA RHESSI mission (launched February 2002) is to investigate the physics of particle acceleration and energy release in solar flares, through imaging and spectroscopy of X-ray gamma-ray continuum and gamma-ray lines emitted by accelerated electrons and ions, respectively. Here I summarize the new solar observations, including the first hard X-ray imaging spectroscopy, the first high resolution spectroscopy of solar gamma ray lines, the first imaging of solar gamma ray lines and continuum, and the highest sensitivity hard X-ray observations of microflares and type III solar radio bursts.

Lin, R. P.↗
NASA NTRS1988

Wavelength-precise slit spectroscopy with optical fiber image scramblers

The application of optical-fiber image scramblers in wavelength-precise slit spectroscopy is discussed together with the design strategy for the optimal instrument configuration incorporating an optical-fiber image scrambler. Particular attention is given to the aspects of data analysis and interpretation techniques which must be specially designed for high-precision spectroscopy. In a specific application to an existing coude spectrograph, the instrumentation and data reduction techniques described in this paper demonstrate an achievable precision corresponding to a systematic radial velocity error of about 30 m/sec.

Heacox, William D.↗
NASA NTRS1975

Self-scanned Digicon - A digital image tube for astronomical spectroscopy

We have successfully fabricated, tested, and operated a digital image tube consisting of a magnetically focused image intensifier tube in which a self-scanned linear array of 1024 silicon photodiodes operating in the EBS mode serves as the photoelectron image detector, amplifier, and intermediate image storage device. Integral on-chip MOS shift registers driven by an external clock sequentially interrogate the photodiodes through MOS FET multiplex switch arrays. Each output frame is a sequence of 256 analog pulses on each of four video lines. Laboratory and observing tests show that the output signal is photoelectron shot noise limited over at least a range of 1-100,000 detected photoelectrons per picture element, indicating that single photon detection is achieved. High-resolution astronomical spectroscopy has been carried out in the coude spectrograph of the 2.7-m telescope at McDonald Observatory. Examples are shown.

Tull, R. G.↗
NASA NTRS1986

On the application of optical-fiber image scramblers to astronomical spectroscopy

Single, step-index optical fibers, when properly employed, can function as optically efficient image scramblers. Their use as optical feeds for astronomical slit spectrographs can reduce zonal error levels in those instruments by orders of magnitude. As a consequence, the application of optical-fiber couplers to new and existing spectrographs may greatly increase the wavelength metric quality of conventional astronomical spectroscopy. The optical efficiencies of fiber couplers of a few tens of meters in length can be comparable to those of typical coude mirror trains in the visible portions of the spectrum. Elements of the design of fiber couplers are illustrated by discussion of a currently operational instrument.

Heacox, W. D.↗
NASA NTRSDate not supplied

Nancy Grace Roman Space Telescope Observatory Implementation and Challenges

NASA’s Nancy Grace Roman Space Telescope (Roman) is a deep space infrared observatory with a Hubble-sized telescope and wide field of regard with a boresight view greater than 200 times that of the Hubble Wide Field Camera 3infrared field of view, that will conduct a suite of science surveys to characterize dark energy and expand the census of exoplanets in our galaxy. Roman will also demonstrate exoplanet coronagraphy with active wavefront control technology and provide general investigator opportunities for the science community. Roman is finishing the critical design phase and is planning for launch in 2026. It will operate at the second Sun-Earth-Moon Lagrange for a five-year primary mission life. The Observatory features a telescope with an existing, repurposed 2.4m primary mirror, a Wide Field Instrument with a near-infrared detector focal plane array and optical elements for imaging and spectroscopy, as well as a Coronagraph instrument technology demonstration for direct imaging and spectroscopy of exoplanets. The telescope and instruments are mounted to an Instrument Carrier for optical metering and isolation from Spacecraft-induced disturbances. The Spacecraft includes a Bus, Solar Array Sunshield, Deployable Aperture Cover, Outer Barrel Assembly, and Star Tracker/Inertial Reference Unit Bench. When fully integrated, Roman will be the largest Observatory assembled and tested at NASA’s Goddard Space Flight Center. The development of scientific satellites is challenging and pushes engineering boundaries to broaden scientific knowledge. The Roman mission implementation is a prime example and expected challenges have been amplified by the foundational decision to use existing, repurposed telescope components. Other unique aspects of the Roman mission, including its survey nature, large data volume, and Observatory packaging, create constrained design spaces that drive competing requirements across Observatory subsystems. Given these challenges, systems engineering has been a critical discipline in balancing implementation decisions and will continue to play a key role in the development of the Roman mission. This paper will discuss details of the Roman Observatory configuration, systems engineering challenges and the decision-making process used to mature the Roman Space Telescope from preliminary design to implementation.

Lisa M L Bartusek↗
NASA NTRS1993

High-resolution imaging gamma-ray spectroscopy with externally segmented germanium detectors

Externally segmented germanium detectors promise a breakthrough in gamma-ray imaging capabilities while retaining the superb energy resolution of germanium spectrometers. An angular resolution of 0.2 deg becomes practical by combining position-sensitive germanium detectors having a segment thickness of a few millimeters with a one-dimensional coded aperture located about a meter from the detectors. Correspondingly higher angular resolutions are possible with larger separations between the detectors and the coded aperture. Two-dimensional images can be obtained by rotating the instrument. Although the basic concept is similar to optical or X-ray coded-aperture imaging techniques, several complicating effects arise because of the penetrating nature of gamma rays. The complications include partial transmission through the coded aperture elements, Compton scattering in the germanium detectors, and high background count rates. Extensive electron-photon Monte Carlo modeling of a realistic detector/coded-aperture/collimator system has been performed. Results show that these complicating effects can be characterized and accounted for with no significant loss in instrument sensitivity.

Callas, J. L.↗