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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Flight Integral Field Spectrograph (IFS) Optical Design for WFIRST Coronagraphic Exoplanet Demonstration

Based on the experience from Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) for WFIRST, we have moved to the flight instrument design phase. The specifications for flight IFS have similarities and differences from the prototype. This paper starts with the science and system requirement, discusses a number of critical trade-offs: such as IFS type selection, lenslet array shape and layout versus detector pixel accuracy, how to accommodate the larger Field Of View (FOV) and wider wavelength band for a potential add-on StarShade occulter. Finally, the traditional geometric optical design is also investigated and traded: reflective versus refractive, telecentric versus non-telecentric relay. The relay before the lenslet array controls the chief angle distribution on the lenslet array. Our previous paper has addressed how the relay design combined with lenslet arraypinhole mask can further compress the residual star light and increase the contrast. Finally, a complete phase A IFS optical design is presented.

Integral Field spectrograph↗
NASA NTRS2017

Predictive Thermal Control Applied to HabEx

Exoplanet science can be accomplished with a telescope that has an internal coronagraph or with an external starshade. An internal coronagraph architecture requires extreme wavefront stability (10 pm change/10 minutes for 10(exp -10) contrast), so every source of wavefront error (WFE) must be controlled. Analysis has been done to estimate the thermal stability required to meet the wavefront stability requirement. This paper illustrates the potential of a new thermal control method called predictive thermal control (PTC) to achieve the required thermal stability. A simple development test using PTC indicates that PTC may meet the thermal stability requirements. Further testing of the PTC method in flight-like environments will be conducted in the X-ray and Cryogenic Facility (XRCF) at Marshall Space Flight Center (MSFC).

Brooks, Thomas E.↗
NASA NTRS2018

Beyond Kepler: Direct Imaging of Exoplanets

The exoplanets field has been revolutionizing astronomy over the past 20+ years and shows no signs of stopping. The next big wave of exoplanet science may come from direct imaging of exoplanets. Several (non-habitable) exoplanets have already been imaged from the ground and NASA is planning an instrument for its 2020s flagship mission (WFIRST) to directly image large exoplanets. One of the key goals of the field is the detection and characterization of "Earth 2.0", i.e. a rocky planet with an atmosphere capable of supporting life. This appears possible with several potential instruments in the late 2020s such as WFIRST with a starshade, Extremely Large Telescopes (ELTs) from the ground, or one of NASA possible flagship missions in the 2030s (HabEx or LUVOIR). Also, if an Earth-like planet exists around Alpha Centauri (A or B), it may be possible to directly image it in the next approx. 5 years with a small space mission such as the Alpha Centauri Exoplanet Satellite (ACESat). I will describe the current challenges and opportunities in this exciting field, as well as the work we are doing at the Exoplanet Technologies group to enable this exciting science.

exoplanet↗
NASA NTRS2017

The Large UV/Optical/Infrared Surveyor (LUVOIR): Decadal Mission Concept Technology Development Overview

The Large Ultraviolet / Optical / Infrared (LUVOIR) Surveyor is one of four large mission concept studies being developed by NASA for consideration in the 2020 Astrophysics Decadal Survey. LUVOIR will support a broad range of science objectives, including the direct imaging and spectral characterization of habitable exoplanets around sun-like stars, the study of galaxy formation and evolution, the epoch of reionization, star and planet formation, and the remote sensing of Solar System bodies. The LUVOIR Science and Technology Definition Team (STDT) has tasked a Technology Working Group (TWG), with more than 60 members from NASA centers, academia, industry, and international partners, with identifying technologies that enable or enhance the LUVOIR science mission. The TWG has identified such technologies in the areas of Coronagraphy, Ultra-Stable Opto-mechanical Systems, Detectors, Coatings, Starshades, and Instrument Components, and has completed a detailed assessment of the state-of-the-art. We present here a summary of this technology assessment effort, as well as the current progress in defining a technology development plan to mature these technologies to the required technology readiness level (TRL).

Decadal Study; Technology; LUVOIR↗
NASA NTRS2019

Breakthroughs in Picometer Ultra-Stable Spatial Metrology Systems for Next Generation Telescopes

Goal is to discover and characterize habitable planet candidates around Sun-like stars. Need 10(exp -10) contrast between reflected earth like planet and sun like stars. Options are internal Coronagraphs (LUVOIR and Habex) and large starshades (Habex) which each have pros and cons. Coronagraphs require 10(exp -10)contrast stability which means the primary mirror must be stable to roughly 10 picometers RMS wavefront over an exposure(minutes). Simplistically: Primary mirror instabilities of 10 picometers in certain spatial frequencies look like planets!

Feinberg, Lee↗
NASA NTRS2016

Exoplanet Standard Definitions and Evaluation Team

In the 2015 run-up to chartering of large mission studies, it became obvious that likely studies (HabEx, LUVOIR) would consider overlapping science cases (e.g. spectroscopy of exo-Earths). The exoplanet community has had some recent experience with apple-to-oranges/apples comparisons: parallel studies, different architectures (telescope, coronagraph masks, starshades). The challenge of parallel studies is to remain consistent over time. The topic was discussed by PAGs and Senior Management: request for “common yardstick, honest broker.” The Management Plan now includes an “Exoplanet Standard Definitions and Evaluation Team.”

Blackwood, Gary↗
NASA NTRSDate not supplied

A Decade of NASA Strategic Astrophysics Technology Investments: Technology Maturation, Infusion, and Other Benefits

NASA’s Astrophysics Division (APD) funds development of cutting-edge technology to enable its missions to achieve ambitious and groundbreaking science goals. These technology development efforts are managed by the Physics of the Cosmos (PCOS), Cosmic Origins (COR), and Exoplanet Exploration (ExE) Programs. The NASA Strategic Astrophysics Technology (SAT) Program was established in 2009 as a new technology maturation program to fill the gap in the Technology Readiness Level (TRL) range from 3 to 6. Since program inception, 100 SAT grants have been openly competed and awarded, along with dozens of direct-funded projects, leading to a host of technologies advancing their TRLs and/or being infused into space and suborbital missions and ground-based projects. We present the portfolio distribution in terms of specific technology areas addressed, including optics, detectors, coatings, coronagraphs, starshades, lasers, electronics, cooling systems, and micro-thruster subsystems. We show an analysis of the rate of TRL advances, infusion success stories, and other benefits such as training the future astrophysics workforce, including students and postdoctoral fellows hired by projects. Finally, we present APD’s current strategic technology maturation priorities for investment, enabling a range of future strategic astrophysics missions

NASA, astrophysics, technology development, optics↗
NASA NTRS2016

Technology needs to discover Earth 2.0

Dr. Nick Siegler of the NASA Jet Propulsion Laboratory (JPL) began his talk by stating that the main goal of the Exoplanet Exploration Program technology effort is to enable future space missions to observe a planetary spectrum of a rocky planet in the habitable zone of its star and understand it in the context of potential life. He went on to say that the main exoplanet discovery tools, the radial velocity and transit techniques, which have discovered more than 95% of the more than 3,400 exoplanets, will not be the techniques to directly image exoplanets, which is needed to get a reflected light spectrum. Spectroscopy will be hard though because there simply aren’t many photons available to use, but it will not be the biggest problem. The biggest problem will be suppressing the light from the stars which can be 10 billion times brighter than a rocky planet in the habitable zone of a Sun analog. Starlight suppression could be done in one of three ways: internal occulters (i.e., coronagraphs), external occulters (i.e., starshades), and nulling interferometers. The latter option is the least technologically mature of the options and one that NASA is not currently pursuing.

Schmitt, Joseph↗
NASA NTRS2018

HabEx Space Telescope Optical System Overview: General Astrophysics Instruments

The HabEx (Habitable Exoplanet) concept study is defining a future space telescope with the primary mission of detecting and characterizing planetary systems around nearby stars. The telescope baseline design includes a high-contrast coronagraph and a starshade to enable the direct optical detection of exoplanets as close as 70 mas to their star. In addition to the study of exoplanets, HabEx carries two dedicated instruments for general astrophysics. The first instrument is a camera enabling imaging on a 3 arc minute field of view in two bands stretching from the UV at 150 nm to the near infrared at 1800 nm. The same instrument can also be operated as a multi-object spectrograph, with resolution of 2000. The second instrument is a high-resolution UV spectrograph operating from 300 nm down to 115 nm with up to 60,0000 resolution. HabEx would provide the highest resolution UV/optical images ever obtained. Diffraction limited at 0.4 µm, it would outperform all current and approved facilities, including the 30 m class ground-based extremely large telescopes (ELTs), which will achieve ~0.01 arcsecond resolution at near-infrared (IR) wavelengths with adaptive optics, but will be seeing-limited at optical wavelengths. HabEx would observe wavelengths inaccessible from the ground, including the UV and in optical/near-IR atmospheric absorption bands. Operating at L2, far above the Earth’s atmosphere and free from the large thermal swings inherent to HST’s low-Earth orbit, HabEx would provide an ultra-stable platform that will enable science ranging from precision astrometry to the most sensitive weak lensing maps ever obtained. Here we discuss the design concepts of the general astrophysics optical instruments for the proposed observatory.

Nissen, Joel↗
NASA NTRS2020

ATSA- A Cold, Active Telescope for Space Astronomy

The National Academies’ Decadal Survey telescope studies have produced mission design concepts that plotpathways into the future to follow on from Hubble, Spitzer, JWST and NGRST. Considering the results of theLUVOIR and HabEx studies in particular, it is clear that segmented mirrors will eventually be needed to providevery large apertures in space and that this architecture presents both a scientific opportunity and an engineeringchallenge. Furthermore, while HabEx and LUVOIR cover a great deal of spectrum, both fall short of the mid-IRregion where general astronomy and astrophysics can be undertaken that would be impossible from terrestrialobservatories and where there also exist spectral features of interest in the search for life. A telescope with similarcapabilities to Habex/LUVOIR but also capable of exoplanet work in spectral regions up to 5 µm would largelybridge the gap between those proposals and TPF-I (which would have operated from about 7 µm upwards), andis therefore worthy of study. The Active Telescope for Space Astronomy (ATSA) design study presents a possiblearchitecture and is moderately sized (6 m) to enable the use of both starshade and coronagraph technologies.While the segment gaps of a segmented primary mirror present a challenge for coronagraphy, the architecturedoes allow direct wavefront control at each segment of that mirror, enabling a great degree of control at theprimary source of contrast degradation. While active systems (for example, deformable mirrors on WFIRSTCGI) are being incorporated into telescope designs today, a fully active mirror system needs further developmentfor a future mission. With this concept in mind, and intending to build on the LUVOIR and HabEx studies, wediscuss the elements of a cooled telescope design enabling both general astrophysics and exoplanet studies fromthe near UV through to the near-IR.

Steeves, John↗
NASA NTRS2022

Initial Laboratory Demonstration of Multi-Star Wavefront Control at the Occulting Mask Coronagraph Testbed

Online Abstract: A majority of Sun-like stars, such as the A and B components of Alpha Centauri, have at least one stellar companion that can introduce additional noise into the field of view of any high-contrast imaging instrument. Multi-Star Wavefront Control (MSWC) is a wavefront-control technique that removes stellar leakage from both stellar components, enabling direct imaging of planets in many binary star systems. We present the latest experimental and modeling results obtained with MSWC as part of the technology development effort focusing on demonstrations conducted on the Occulting Mask Coronagraph (OMC) testbed at JPL. OMC has a layout similar to the Roman Space Telescope coronagraph instrument (CGI), and we used a MSWC mask similar to the one that was contributed to the Roman CGI. Our results represent the first demonstrations of this technique on the OMC testbed, with the ultimate goal of demonstrating full MSWC with validated models at contrast levels relevant to Roman CGI. Technical Review Abstract: A majority of Sun-like stars have at least one stellar companion that can introduce additional noise into the field of view of any high-contrast imaging instrument, limiting the achievable contrast. These include high-quality target stars such as the A and B components of Alpha Centauri, our nearest stellar neighbor. Enabling direct imaging of binary stars has the potential to increase the scientific yield for coronagraphic instruments planned on NASA's future space missions including the Roman Space Telescope and the next IR/O/UV Flagship recommended by Astro2020. Multi-Star Wavefront Control (MSWC) is a wavefront-control technique that simultaneously removes the (mutually incoherent) stellar leakage from both stellar components, enabling direct imaging of planets in many binary star systems. MSWC is an algorithmic technique and can be used with existing wavefront control systems on coronagraphic instruments (as well as starshades if a deformable mirror is available in the optical path). We summarize the latest experimental and numerical results obtained with MSWC as part of the technology development effort to demonstrate compatibility with existing high-contrast imaging platforms for this technique. The Super-Nyquist regime of MSWC was tested in vacuum at JPL's High Contrast Imaging Testbed (HCIT) on the Decadal Survey Testbed (DST) reaching 8.6e-9 contrast in a 10% band. Recently, the Occulting Mask Coronagraph (OMC) testbed at JPL is being prepared for demonstrations of Multi-Star Wavefront Control. A shaped pupil mask similar to the contributed MSWC mask on the Roman Space Telescope's coronagraph instrument has been recently manufactured including matching Lyot and focal plane masks and being installed on the OMC testbed. The goal of this experiment is a demonstration of MSWC using validated models on a testbed configuration and at contrast levels relevant to the Roman coronagraphic instrument.

High-contrast imaging↗
NASA NTRSDate not supplied

Laboratory Demonstration of High Contrast with the PIAACMC Coronagraph on an Obstructed and Segmented Aperture

Coronagraphs (together with starshades) are an important tool to directly image and characterize exoplanets, and enable the search for biomarkers in reflected light on potentially habitable worlds. Their performance and efficiency has steadily been improving over the past several decades, but has not yet reached performance limits. In particular, the expected exoplanet yield for missions such as the Astro2020-recommended “IR/O/UV Flagship” can still be improved by factors of at least 2-3, simply by continued improvements in coronagraph performance, before they plateau due to physics limits. One possible architecture that can enable at least a part of this improvement is the Phase-Induced Amplitude Apodization Complex Mask Coronagraph (PIAACMC). Itoffersthe advantages of high throughput, small inner working angle (IWA),and almost noloss inPSF sharpness, and natively supports obstructed and segmented apertures, which is essential to the Astro2020 “IR/O/UV Flagship”mission. Historically, key disadvantages of PIAA have been poor tolerance to stellar angular sizes and maturity, but latest designs and demonstrations have made significant strides in this respect.In this paper, we present the current status and overview of our program to mature the PIAACMC technology. We first review PIAACMC designs for LUVOIR-A and B, which resultedin improved expected yield of Exo-Earths relative tothe baselines for both mission concepts. In particular, for LUVOIR-B, the yield improves from 28 to 42due to improvedtolerance to stellar angular size in our design. The improvement in yield is marginal for LUVOIR-A, but our design enables detecting planets around smaller diameter stars (nearby K-dwarfs and/or farther FG stars). We also describe our modeling and vacuum demonstrationsfor the LUVOIR-A aperture(which is more challengingthan LUVOIR-B due to the central obstruction).The demonstration included a LUVOUR-A pupil mask, an on-axis PIAA set of 2 mirrors with central holes, a Boston Micromachines DM, a patterned CMC mask, Lyot stop, and supporting masks and optics. Demonstrations were conducted at JPL’s High Contrast Imaging Testbed (HCIT) using several characterization andwavefront control techniques (primarily standard EFC, several experimental techniques were attempted, as well as speckle nulling). So far, our results include 1.9e-8 raw contrast in 10% broadband light between 3.5 and 8 l/D; 4.1e-8 and 1.6e-9 coherent contrasts in monochromatic light between 2-4 and 4-8 l/D, respectively. We also present measurements and analysis of sensitivity to tip/tilt jitter and stellar angular size. Finally, we compare our test results to models, present an analysis of our limiting factors, and explorefuture prospectsfor improvement based on validated models.

Coronagraph↗
NASA NTRSDate not supplied

Multi-Star Wavefront Control: Update on Technology Development for Roman Space Telescope and Habitable Worlds Observatory

A majority of Sun-like stars have at least one stellar companion that can introduce additional noise into the field of view of any high-contrast imaging instrument, limiting the achievable contrast. These include high-quality target stars such as the A and B components of Alpha Centauri, our nearest stellar neighbor. Enabling direct imaging of binary stars has the potential to increase the scientific yield for coronagraphic instruments planned on NASA's future space missions and concepts, including the Roman Space Telescope and the Astro2020 IR/O/UV flagship. Multi-Star Wavefront Control (MSWC) is a wavefront-control technique that simultaneously removes the (mutually incoherent) stellar leakage from both stellar components, enabling direct imaging of planets in many binary star systems. MSWC is an algorithmic technique and can be used with existing wavefront control systems on coronagraphic instruments (as well as starshades if a deformable mirror is available in the optical path) including planned observations on the upcoming PICTURE-D balloon flight. We report on the latest experimental and numerical results obtained with MSWC as part of the technology development effort to demonstrate compatibility with existing high-contrast imaging platforms for this technique. We first report on functional tests carried out at Subaru's SCExAO instrument operating in-air and showing the sub-Nyquist mode at 4.1e-6 contrast in monochromatic light. The Super-Nyquist regime of MSWC was recently tested in vacuum at JPL's High Contrast Imaging Testbed (HCIT) on the Decadal Survey Testbed (DST) reaching 8.6e-9 contrast in a 10% band. We also report on results for the current stage of vacuum testing at HCIT's Occulting Mask Coronagraph (OMC) testbed using a mask similar to the contributed MSWC mask on the Roman Space Telescope's coronagraph instrument which has demonstrated suppression at the 9.8e-9 contrast at Super-Nyquist separations around the 3rd diffraction order and is planned to use a novel binary source simulator.

high-contrast imaging↗
NASA NTRSDate not supplied

Novel Deployable Sunshade for a Formation-Flying Telescope

- Deployable sunshade is based on folding paper party decoration. - Cellular structure creates strong, rigid form. - Instead of folding flat, the cellular fan is wrapped around a central hollow core to accommodate a focusing optic. - Imbedded spring ribs deploy the cellular fan into a large disk. - Shade is constructed of thermal blanket materials and is sewn together rather than glued. - Design bears some resemblance to JPL starshade, but is a much simpler design - JPL design includes pantograph-like mechanical structure and motors to drive deployment.

Anne-Marie Novo-Gradac↗
NASA NTRS2011

Design and Verification of External Occulters for Direct Imaging of Extrasolar Planets

An occulter is an optical element which is placed in front of the telescope to block most of the light from a star before it reaches the optics inside, without blocking the planet.In our case, we use two spacecraft ying in formation: First has its edge shaped to cancel the starlight Second is the telescope which images the star and planet

starshades↗