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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Science Yield Estimates and Sensitivities With the AstroPIC Integrated Photonic Coronagraph for the Habitable Worlds Observatory

The Habitable Worlds Observatory (HWO) flagship has a goal to survey ~100 of the nearest stellar systems and their habitable zones in order to detector and spectroscopically characterize ~25 potentially “Earth-like planets” (or “Exoearths”). The HWO telescope will feature a >6-m diameter aperture and a coronagraph that will suppress starlight by ten orders of magnitude to enable the detection and characterization of Earth analogues in the habitable zone. Three Exploratory Analytic Cases (EACs) are currently considering different aperture configurations for HWO including on-axis and off-axis apertures and both different hexagonal and keystone segmentation configurations. Photonic Integrated Circuits (PICs) offer a path to miniaturize traditional, bulk optics coronagraph functionality reducing risk margins and increasing mission science exoearth yields for the HWO mission. We have developed a simulation pipeline that enables evaluation of the AstroPIC photonic integrated coronagraph through to estimates mission yields. We present sensitivities to aberrations for different types of segmentation and low-order aberrations for HWO EACs demonstrating that AstroPIC is suitable for both on-axis and off-axis configurations. We perform a parametric sweep of the exoearth science yield sensitivities in terms of key coronagraph parameters including coronagraphic end-to-end throughput, inner working angle, robustness to aberrations, and bandwidth. We consider both a hybrid and a pure photonic architecture; a pure integrated photonic architecture provides the greatest potential in science yield improvements, although a hybrid PIC limited in its numbers of modes can provide complementary science to a traditional, bulk-optic coronagraph and increasing the estimated science yield when operated jointly.

Photonics↗
NASA NTRS2011

Deep UV to NIR Space Telescopes and Exoplanet Coronagraphs: A Trade Study on Throughput, Polarization, Mirror Coating Options and Requirements

The NASA Exoplanet program and the Cosmic Origins program are exploring technical options to combine the visible to NIR performance requirements of a space coronagraph with the general astrophysics requirements of a space telescope covering the deep UV spectrum. Are there compatible options in terms of mirror coatings and telescope architecture to satisfy both goals? In this paper, we address some of the main concerns, particularly relating to polarization in the visible and throughput in the UV. Telescope architectures employing different coating options compatible with current technology are considered in this trade study.

coronagraph↗
NASA NTRS2004

An Infrared Telescope for Planet Detection and General Astrophysics

NASA plans to launch a Terrestrial Planet Finder (TPF) mission in 2014 to detect and characterize Earth-like planets around nearby stars, perform comparative planetology studies, and obtain general astrophysics observations. During our recently completed a TPF Mission Architecture study for NASA/JPL we developed the conceptual design for a 28-meter telescope with an IR Coronagraph that meets these mission objectives. This telescope and the technology it embodies are directly applicable to future Far-IR and Submillimeter space missions. The detection of a 30th magnitude planet located within 50 milli-arc-seconds of a 5th (Visual) magnitude star is an exceptionally challenging objective. Observations in the thermal infrared (7-17 microns) are somewhat easier since the planet is "only" 15(sup m) fainter than the star at these wavelengths, but many severe challenges must still be overcome. These challenges include: 1. Designing a coronagraph for star:planet separations less than or equal to lambda/D. 2. Developing the deployment scheme for a 28m space telescope that can fit in an existing launch vehicle payload fairing. 3. Generating configuration layouts for the IR telescope, coronagraph, spacecraft bus, sunshade, solar array, and high-gain antenna. 4. Providing: Structural stability to within 10 microns to support the optics. Thermal control to achieve the necessary structural stability, as well as providing a stable (approx. 30K) thermal environment for the optics. Dynamics isolation from potential jitter sources. 5. Minimizing launch mass to provide the maximum payload for the science mission Interfacing to an EELV Heavy launch vehicle, including acoustic and stress loads for the launch environment. 6. Identifying the key technologies (which can be developed by 2009) that will enable TPF mission to be performed. 7. Generating a manufacturing plan that will permit TPF to be developed at a reasonable cost and schedule. Many of these design challenges result in inherently conflicting requirements on the design of TPF. Drawing on our experience with large space telescopes such as the Chandra X-ray Observatory and the Next Generation Space Telescope, we have created a conceptual design for TPF that successfully meets these challenging requirements. This paper describes our solution to these challenges.

Lillie, C. F.↗
NASA NTRSDate not supplied

Experimental Verification of the Parabolic Deformable Mirror for the ExoSpec Project

For the Habitable Worlds Observatory (HWO), it is essential to broaden the controllable wavelength bandwidth for high-contrast imaging and spectroscopy to increase the exoEarth yield and characterization. The Parabolic Deformable Mirrors (PDM) subpackage, under the NASA Headquarters-directed Exoplanet Spectroscopy (ExoSpec) Work Package, is specifically tailored to do so. We have successfully procured a first-generation (Gen 1) PDM device and completed in-depth characterization of the device. This robust evaluation has become instrumental in informing subsequent stages of development, particularly in shaping the design and specifying requirements for the next generation, Gen 2, PDM device. We have built a testbed in an environmentally controlled cleanroom to experimentally demonstrate the use of a PDM in a coronagraph instrument with an integral field spectrograph (IFS). This versatile testbed is designed to test different DM architectures, low-order wavefront sensing schemes, and a lenslet-based IFS. This provides us with a basis for comparison with different DM configurations: 1) flat DM, 2) PDMs, and 3) a flat DM and PDMs. In this communication, we will discuss the testbed design and updates, PDM characterization, and Gen 2 requirement definitions.

Hari B. Subedi↗
NASA NTRS2004

Terrestrial Planet Finder Coronagraph : technology and mission design studies

The Terrestrial Planet Finder (TPF) coronagraph study involves exploring the technologies that enable a coronagraph style instrument to image and characterize earth-like planets orbiting nearby stars. Testbeds have been developed to demonstrate the emerging technologies needed for this effort and an architecture study has resulted in designs of a facility that will provide the environment needed for the technology to function in this role. A broad community of participants is involved in this work through studies, analyses, fabrication of components, and participation in the design effort. The scope of activities - both on the technology side and in the architecture study side - will be presented in this paper. The status and the future plans of the activities will be reviewed.

space↗
NASA NTRSDate not supplied

Experimental Verification of the Parabolic Deformable Mirror for the ExoSpec Project

For the Habitable Worlds Observatory, it is essential to broaden the controllable wavelength bandwidth for high-contrast imaging and spectroscopy to increase the exoEarth yield and characterization. The Parabolic Deformable Mirrors (PDM) under the NASA Headquarters directed ExoSpec Work package is specifically tailored to do so. We have successfully procured a generation 1 (Gen 1) PDM device and completed in-depth characterization of the device. This robust evaluation has become instrumental in informing subsequent stages of development, particularly in shaping the design and specifying requirements for the next generation, Gen2, PDM device. We have built a testbed in an environmentally controlled cleanroom to experimentally demonstrate the use of a parabolic DM in a coronagraph instrument as well an integral field spectrograph (IFS). This versatile testbed is designed to test different DM architectures, various low-order wavefront schemes, and a lenslet based IFS. This provides us with a basis for comparison with different DM configurations – 1) flat DM, 2) parabolic DMs, and 3) a flat DM and parabolic DMs. In this communication, we will discuss the testbed design and updates, parabolic DM characterization, Gen 2 requirement definitions, and different tests planned for the testbed.

Hari Subedi↗
NASA NTRS2015

Maturing CCD Photon-Counting Technology for Space Flight

This paper discusses charge blooming and starlight saturation - two potential technical problems - when using an Electron Multiplying Charge Coupled Device (EMCCD) type detector in a high-contrast instrument for imaging exoplanets. These problems especially affect an interferometric type coronagraph - coronagraphs that do not use a mask to physically block starlight in the science channel of the instrument. These problems are presented using images taken with a commercial Princeton Instrument EMCCD camera in the Goddard Space Flight Center's (GSFC), Interferometric Coronagraph facility. In addition, this paper discusses techniques to overcome such problems. This paper also discusses the development and architecture of a Field Programmable Gate Array and Digital-to-Analog Converter based shaped clock controller for a photon-counting EMCCD camera. The discussion contained here will inform high-contrast imaging groups in their work with EMCCD detectors.

Mallik, Udayan↗
NASA NTRS2016

Using JWST Heritage to Enable a Future Large Ultra-Violet Optical Infrared Telescope

To the extent it makes sense, leverage JWST knowledge, designs, architectures, GSE. Develop a scalable design reference mission (9.2 meter). Do just enough work to understand launch break points in aperture size. Demonstrate 10 pm stability is achievable on a design reference mission. Make design compatible with starshades. While segmented coronagraphs with high throughput and large bandpasses are important, make the system serviceable so you can evolve the instruments. Keep it room temperature to minimize the costs associated with cryo. Focus resources on the contrast problem. Start with the architecture and connect it to the technology needs.

JWST UV Optical Infrared↗
NASA NTRS2016

ATLAST and JWST Segmented Telescope Design Considerations

To the extent it makes sense, leverage JWST (James Webb Space Telescope) knowledge, designs, architectures. GSE (Ground Support Equipment) good starting point. Develop a full end-to-end architecture that closes. Try to avoid recreating the wheel except where needed. Optimize from there (mainly for stability and coronagraphy). Develop a scalable design reference mission (9.2 meters). Do just enough work to understand launch break points in aperture size Demonstrate 10 pm (phase modulation) stability is achievable on a design reference mission. A really key design driver is the most robust stability possible!!! Make design compatible with starshades. While segmented coronagraphs with high throughput and large bandpasses are important, make the system serviceable so you can evolve the instruments. Keep it room temperature to minimize the costs associated with cryo. Focus resources on the contrast problem. Start with the architecture and connect it to the technology needs.

Feinberg, Lee↗
NASA NTRS2019

Habitable Exoplanet Observatory (HabEx) starshade-only architectures

The HabEx mission concept is intended to directly image planetary systems around nearby stars, and to perform a wide range of general astrophysics and solar system observations. The baseline HabEx design would use both a coronagraph and a starshade for exoplanet discovery and characterization. We describe a lower-cost alternative HabEx mission design, which would only use a starshade for exoplanet science. The starshade would provide excellent exoplanet science performance, but for a smaller number of detected exoplanets of all types, including exoEarth candidates, and a smaller fraction of exoplanets with measured orbits. The full suite of HabEx general astrophysics and solar-system science would be supported.

Benson, Jonathan↗
NASA NTRS2019

Design and Modeling of the Off-Axis Parabolic Deformable (OPD) Mirror Laboratory

Coronagraph-equipped direct imaging missions need an active wavefront control system to cancel out the optical aberrations that degrade the performance of the coronagraphs. A fast steering mirror is used to control Line-of-Sight (LoS) pointing error caused by the telescope jitter. In addition to controlling other low-order aberrations such as astigmatism and coma, high stroke, high actuator density deformable mirrors (DMs) are also used to control the electric field at the required high spatial frequencies. We are designing a testbed to verify a different deformable architecture, where the powered optic in the optical train are controllable and have lower actuator count compared to the existing DMs with flat nominal surfaces. This simplifies the packaging issue for space missions and reduces both cost and risk of having the entire coronagraph instrument's performance depending on one or two high-actuator count DMs. The testbed would also be capable of testing different low-order wavefront sensing algorithms, which focuses in the near-term on a new adaptive Kalman filtering and gradient decent method to estimate the harmonic LoS errors that affect space telescopes. In long run, we would test different machine learning techniques to estimate low-order aberrations and non-linear algorithms for digging the region of high contrast called the dark holes (DH).

Subedi, Hari↗
NASA NTRS2019

Design and Modeling of the Off-Axis Parabolic Deformable Mirror Laboratory

Coronagraph-equipped direct imaging missions need an active wavefront control system to cancel out the optical aberrations that degrade the performance of the coronagraphs. A fast steering mirror is used to control Line-of-Sight (LoS) pointing error caused by the telescope jitter. In addition to controlling other low-order aberrations such as astigmatism and coma, high stroke, high actuator density deformable mirrors (DMs) are also used to control the electric field at the required high spatial frequencies. We are designing a testbed to verify a different deformable architecture, where the powered optic in the optical train are controllable and have lower actuator count compared to the existing DMs with flat nominal surfaces. This simplifies the packaging issue for space missions and reduces both cost and risk of having the entire coronagraph instrument's performance depending on one or two high-actuator count DMs. The testbed would also be capable of testing different low-order wavefront sensing algorithms, which focuses in the near-term on a new adaptive Kalman filtering and gradient decent method to estimate the harmonic LoS errors that affect space telescopes. In long run, we would test different machine learning techniques to estimate low-order aberrations and non-linear algorithms for digging the region of high contrast called the dark holes (DH).

Communication↗
NASA NTRSDate not supplied

The Coronal Microscale Observatory

It has been a longstanding challenge to identify the mechanisms responsible for heating the solar corona, in part because heating, whether by waves or magnetic reconnection, is thought to be concentrated in thus far unresolved volumes with characteristic scales ≲100 km. The Coronal Microscale Observatory (CMO) is a mission concept designed to image these microscale heating events, identify the dominant physical mechanisms that control their initiation and evolution, and understand their effects on the formation of the solar wind. CMO positions three spacecraft and three instruments near the Sun-Earth L1 Lagrange point. One instrument is a cluster of 6 coaligned extreme ultraviolet (EUV) telescopes that image a common field of view with ultrahigh angular resolution (0.02−0.07 arcsec) in narrow wavelength bands, each sensitive to emission from plasma in a limited temperature range. The second instrument is a multi-band, full-disk, externally occulted coronagraph. Finally, a two-band fine scale EUV imager (resolution 0.3 arcsec) provides a larger field of view for context and additional science. The three CMO craft fly in precise formation to ensure that the EUV imagers point to a desired target on the Sun and the external occulter accurately blocks the solar disk. The novel mission architecture arises from the intrinsically long EUV focal length (≳100 m) of diffractive optics known as photon sieves, which achieve nearly diffraction-limited EUV imaging but require a distributed telescope, in which the optics and- the image sensors are on separate spacecraft. Two spacecraft are also needed to position an external occulter 200 m in front of the coronagraph, which enables visible-light imaging of the corona very close to the solar limb with undiminished angular resolution. Recent advances in fabricating ultraprecise and smooth reflective optics suggest that a conventional (single spacecraft)EUV “microscope” may now be feasible in an Explorer-class mission that could achieve a subset of the scientific objectives of CMO.

Douglas Rabin↗
NASA NTRS2006

Large Stroke, Picometer Resolution Hexapod for Dynamic Mirror Positioning

Viewgraph presentation reviews the Fast Picometer Mirror mounting (FPMM) for the Terrestrial Planet Finder Coronagraph (TPF-C). Included in the presentation are slides with an overviews of the TPF-C, the requirements of the FPMM, the selection of the materials using the ACE system, and the architecture of the FPMM.

Ohl, Raymond G.↗
NASA NTRS2018

Mirror Design Study for a Segmented HabEx System

NASA is exploring telescope and mirror technology options to meet the demanding science goals of the proposed HabEx space telescope. A key priority for the HabEx mission concept would be to leverage affordable telescope solutions that can meet challenging telescope performance requirements with a demanding program timeline. The baseline approach for HabEx is to use an unobscured, monolithic primary mirror with a coronagraph to optimize system performance. NASA is performing an initial study to investigate the feasibility of a HabEx Lite concept which would not leverage a coronagraph and would therefore, have lower exoEarth yield as a consequence, but could provide system mass, cost, and schedule advantages. The HabEx Lite concept leverages replicated, ULE® mirror segments to provide an attractive, alternative telescope architecture to meet the HabEx threshold mission needs. We present the initial mirror design and performance assessment for the HabEx Lite concept.

Schulz, Kevin↗
NASA NTRS2019

Technologies to Enable the Next Great Observatory

The Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR) is one of four mission concepts being studied by NASA for the 2020 Decadal Survey in Astronomy and Astrophysics. Enabling a mission as ambitious as LUVOIR requires an array of technologies. Critically, a systems-level approach must be taken to developing these technologies, guided by architecture studies to place each technology in the appropriate system context. Three technology systems enable the LUVOIR science objectives: the system, the system, and the system. Each of the technology systems comprise the individual technology components that must be developed and demonstrated as a system. Supporting engineering manufacturing development efforts are also identified for early risk reduction. It is important to note that the high-contrast coronagraph instrument and ultra-stable segmented telescope technology systems are tightly coupled; the performance capabilities of one system drive the requirements of the other. Similarly, the ultraviolet instrumentation technology system is loosely coupled to the other two; while the relative performance affects each system, they do not necessarily drive one another. This coupling between systems requires continuous cross-validation between the technology development paths. It is therefore critical that the technology development plan be executed in parallel with a detailed Pre-Phase A Architecture Study to provide the necessary systems-level perspective and cross-validation.

Bolcar, Matthew R.↗
NASA NTRS2021

A Layered Debris Disk around M Star TWA 7 in Scattered Light

We have obtained Hubble Space Telescope (HST) coronagraphic observations of the circumstellar disk around M star TWA 7 using the Space Telescope Imaging Spectrograph (STIS) instrument in visible light. Together with archival observations, including HST/NICMOS using the F160W filter and Very Large Telescope/SPHERE at the H-band in polarized light, we investigate the system in scattered light. By studying this nearly face-on system using geometric disk models and Henyey–Greenstein phase functions, we report a new discovery of a tertiary ring and a clump. We identify a layered architecture: three rings, a spiral, and an ≈150 au 2 elliptical clump. The most extended ring peaks at 28 au, and the other components are on its outskirts. Our point-source detection-limit calculations demonstrate the necessity of disk modeling in imaging fainter planets. Morphologically, we witness a clockwise spiral motion, and the motion pattern is consistent with both solid body motion and local Keplerian motion; we also observe underdensity regions for the secondary ring that might result from mean-motion resonance or moving shadows: both call for re-observations to determine their nature. Comparing multi-instrument observations, we obtain blue STIS-NICMOS color, a STIS-SPHERE radial distribution peak difference for the tertiary ring, and a high SPHERE-NICMOS polarization fraction; these aspects indicate that TWA 7 could retain small dust particles. By viewing the debris disk around M star TWA 7 at a nearly face-on vantage point, our study allows for the understanding of such disks in scattered light in both system architecture and dust property.

Debris disks↗