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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

James Webb Space Telescope Optical Telescope Element/Integrated Science Instrument Module (OTIS) Status

The James Webb Space Telescope Optical Telescope Element (OTE) and Integrated Science Instrument Module (ISIM) are integrated together to form the OTIS. Once integrated, the OTIS undergoes primary mirror center of curvature optical tests, electrical and operational tests, acoustics and vibration testing at the Goddard Space Flight Center before being shipped to the Johnson Space Center for cryogenic optical testing of the OTIS. In preparation for the cryogenic optical testing, the JWST project has built a Pathfinder telescope and has completed two Optical Ground System Equipment (OGSE) cryogenic optical tests with the Pathfinder. In this paper, we will summarize optical test results to date and status the final Pathfinder test and the OTIS integration and environmental test preparations

Feinberg, Lee↗
NASA NTRS2016

James Webb Space Telescope Optical Telescope Element Integrated Science Instrument Module (OTIS) Status

The James Webb Space Telescope Optical Telescope Element (OTE) and Integrated ScienceInstrument Module (ISIM)are integrated together to form the OTIS. Once integrated, the OTIS undergoes primary mirrorcenter of curvatureoptical tests, electrical and operational tests, acoustics and vibration testing at the Goddard SpaceFlight Center beforebeing shipped to the Johnson Space Center for cryogenic optical testing of the OTIS. In preparationfor the cryogenicoptical testing, the JWST project has built a Pathfinder telescope and has completed two OpticalGround SystemEquipment (OGSE) cryogenic optical tests with the Pathfinder. In this paper, we will summarize opticaltest results todate and status the final Pathfinder test and the OTIS integration and environmental test preparations

Feinberg, Lee↗
NASA NTRSDate not supplied

Technical Oversight of the Nancy Grace Roman Space Telescope Optical Telescope Assembly (OTA) Element Procurement: Opportunities, Challenges, & Lessons Learned (2024 Update)

Nancy Grace Roman Space Telescope Optical Telescope Assembly (OTA) is an out-of-house procurement from L3Harris currently being integrated and tested in Rochester, NY. Building upon L3Harris’s decades of success producing world-class optical systems for government and commercial customers offers NASA a proven partner and a tremendous opportunity for high performance and value. Inheriting significant portions of the telescope (including the primary and secondary mirror, composite metering structures and alignment drives) from a previous program presents the opportunity to save cost and schedule but constrains the design space for the unique challenges of the Roman mission. This seminar will cover a brief description of the OTA and its history, some of the challenges posed by incorporating an established product line and inherited hardware into a Class A mission, and some approaches and lessons learned that may be helpful for those structuring new missions or providing technical oversight of out-of-house procurements.

Joshua Abel↗
NASA NTRS2012

James Webb Space Telescope Optical Telescope Element Mirror Development History and Results

In a little under a decade, the James Webb Space Telescope (JWST) program has designed, manufactured, assembled and tested 21 flight beryllium mirrors for the James Webb Space Telescope Optical Telescope Element. This paper will summarize the mirror development history starting with the selection of beryllium as the mirror material and ending with the final test results. It will provide an overview of the technological roadmap and schedules and the key challenges that were overcome. It will also provide a summary or the key tests that were performed and the results of these tests.

Feinber, Lee D.↗
NASA NTRS2012

James Webb Space Telescope Optical Telescope Element Mirror Coatings

James Webb Space Telescope (JWST) Optical Telescope Element (OTE) mirror coating program has been completed. The science goals of the JWST mission require a uniform, low stress, durable optical coating with high reflectivity over the JWST spectral region. The coating has to be environmentally stable, radiation resistant and compatible with the cryogenic operating environment. The large size, 1.52 m point to point, light weight, beryllium primary mirror (PM) segments and flawless coating process during the flight mirror coating program that consisted coating of 21 flight mirrors were among many technical challenges. This paper provides an overview of the JWST telescope mirror coating program. The paper summarizes the coating development program and performance of the flight mirrors.

Keski-Kuha, Ritva A.↗
NASA NTRS2019

James Webb Space Telescope Optical Telescope Element / Integrated Science Instrument Module (OTIS) Cryogenic Vacuum Test Part I: Thermal Architecture

The James Webb Space Telescope (JWST), set to launch in early 2019, is currently undergoing a series of system-level environmental tests to verify its workmanship and end-to-end functionality. As part of this series, the Optical Telescope Element and Integrated Science Instrument Module (OTIS) Cryo-Vacuum (CV) test, the most complex cryogenic test executed to date by NASA, was completed in 2017 at the Johnson Space Center's Chamber A facility. The OTIS CV test was intended as a comprehensive test of the integrated instrument and telescope systems to fully understand its optical, structural, and thermal performance within its intended flight environment. Due to its complexity, extensive pre-test planning was required to ensure payload safety and compliance with all limits and constraints. A comprehensive thermal analysis campaign was undertaken to predict the behavior of the test payload during its transition to cryogenic temperatures and back to ambient, and exhaustive preparations for off-nominal scenarios were studied due to the increased possibility of unanticipated events during the 100-day test length. This current four-part online course for the NASA Engineering and Safety Center (NESC) Academy gives a thorough overview of the mutiple years of preparation executed by hundreds of individuals to ensure the success of the JWST OTIS CV Test. Part I will introduce the major components of James Webb and specifically the OTIS CV Test thermal architecture. Part II will encompass the extensive thermal analysis performed to prepare for the test. Part III will talk about the preparations for off-nominal events: what analysis was done, and how steps were taken pre-test to anticipate unexpected circumstances and mitigate their impacts to hardware and test timeline. Part IV is a recap of the lessons learned from the thermal perspective for both the payload and ground support equipment (GSE) test conductors. It is hoped that the insight gained from the OTIS CV test campaign will benefit planning and execution for upcoming large cryogenic missions.

OTIS↗
NASA NTRS2019

James Webb Space Telescope Optical Telescope Element / Integrated Science Instrument Module (OTIS) Cryogenic Vacuum Test Part II: Thermal Analysis

The James Webb Space Telescope (JWST), set to launch in early 2019, is currently undergoing a series of system-level environmental tests to verify its workmanship and end-to-end functionality. As part of this series, the Optical Telescope Element and Integrated Science Instrument Module (OTIS) Cryo-Vacuum (CV) test, the most complex cryogenic test executed to date by NASA, was completed in 2017 at the Johnson Space Center's Chamber A facility. The OTIS CV test was intended as a comprehensive test of the integrated instrument and telescope systems to fully understand its optical, structural, and thermal performance within its intended flight environment. Due to its complexity, extensive pre-test planning was required to ensure payload safety and compliance with all limits and constraints. A comprehensive thermal analysis campaign was undertaken to predict the behavior of the test payload during its transition to cryogenic temperatures and back to ambient, and exhaustive preparations for off-nominal scenarios were studied due to the increased possibility of unanticipated events during the 100-day test length. This current four-part online course for the NASA Engineering and Safety Center (NESC) Academy gives a thorough overview of the multiple years of preparation executed by hundreds of individuals to ensure the success of the JWST OTIS CV Test. Part I will introduce the major components of James Webb and specifically the OTIS CV Test thermal architecture. Part II will encompass the extensive thermal analysis performed to prepare for the test. Part III will talk about the preparations for off-nominal events: what analysis was done, and how steps were taken pre-test to anticipate unexpected circumstances and mitigate their impacts to hardware and test timeline. Part IV is a recap of the lessons learned from the thermal perspective for both the payload and ground support equipment (GSE) test conductors. It is hoped that the insight gained from the OTIS CV test campaign will benefit planning and execution for upcoming large cryogenic missions.

Testing↗
NASA NTRS1980

Space Telescope optical telescope assembly

The optical quality and stability requirements of the Space Telescope optical design rely on state-of-the-art developments in optics, structures, and sensors. This paper describes key elements of the design implementation of the Space Telescope's performance requirements.

Mccarthy, D. J.↗
NASA NTRSDate not supplied

Commissioning the James Webb Space Telescope Optical Telescope Element

The James Webb Space Telescope (JWST) launched on December 25th, 2021. The observatory was deployed and commissioned during its first six months. The Optical Telescope Element includes both large deployments of the Deployable Tower Assembly, Secondary Mirror Support Structure and the Primary Mirror Wings and it includes the deployment and alignment of the 18 primary mirror segments and the secondary mirror. The initial phase included cooldown and ice mitigation efforts followed by telescope deployments, mirror deployment and wavefront sensing and control. This paper will discuss the entire OTE commissioning from deployment through alignment including a discussion of results and lessons learned.

Lee D Feinberg↗
NASA NTRS1976

Space telescope optical telescope assembly/scientific instruments. Phase B: -Preliminary design and program definition study; Volume 2A: Planetary camera report

Development of the F/48, F/96 Planetary Camera for the Large Space Telescope is discussed. Instrument characteristics, optical design, and CCD camera submodule thermal design are considered along with structural subsystem and thermal control subsystem. Weight, electrical subsystem, and support equipment requirements are also included.

Source record↗
NASA NTRS1991

Image inversion analysis of the HST OTA (Hubble Space Telescope Optical Telescope Assembly), phase A

Technical work during September-December 1990 consisted of: (1) analyzing HST point source images obtained from JPL; (2) retrieving phase information from the images by a direct (noniterative) technique; and (3) characterizing the wavefront aberration due to the errors in the Hubble Space Telescope (HST) mirrors, in a preliminary manner. This work was in support of JPL design of compensating optics for the next generation wide-field planetary camera on HST. This digital technique for phase retrieval from pairs of defocused images, is based on the energy transport equation between these image planes. In addition, an end-to-end wave optics routine, based on the JPL Code 5 prescription of the unaberrated HST and WFPC, was derived for output of the reference phase front when mirror error is absent. Also, the Roddier routine unwrapped the retrieved phase by inserting the required jumps of +/- 2(pi) radians for the sake of smoothness. A least-squares fitting routine, insensitive to phase unwrapping, but nonlinear, was used to obtain estimates of the Zernike polynomial coefficients that describe the aberration. The phase results were close to, but higher than, the expected error in conic constant of the primary mirror suggested by the fossil evidence. The analysis of aberration contributed by the camera itself could be responsible for the small discrepancy, but was not verified by analysis.

Litvak, M. M.↗
NASA NTRS1976

Space telescope optical telescope assembly/scientific instruments. Phase B: Preliminary design and program definition study. Volume 2A. focal plane camera

Trade studies were conducted to ensure the overall feasibility of the focal plane camera in a radial module. The primary variable in the trade studies was the location of the pickoff mirror, on axis versus off-axis. Two alternatives were: (1) the standard (electromagnetic focus) SECO submodule, and (2) the MOD 15 permanent magnet focus SECO submodule. The technical areas of concern were the packaging affected parameters of thermal dissipation, focal plane obscuration, and image quality.

Source record↗
NASA NTRS1976

Space telescope optical telescope assembly/scientific instruments. Phase B: Preliminary design and program definition study. Volume 2A(3): Astrometry

Wide field measurements, namely, measurements of relative angular separations between stars over a relatively wide field for parallax and proper motion determinations, were made with the third fine guidance sensor. Narrow field measurements, i.e., double star measurements, are accomplished primarily with the area photometer or faint object camera at f/96. The wavelength range required can be met by the fine guidance sensor which has a spectral coverage from 3000 to 7500 A. The field of view of the fine guidance sensor also exceeds that required for the wide field astrometric instrument. Requirements require a filter wheel for the wide field astrometer, and so one was incorporated into the design of the fine guidance sensor. The filter wheel probably would contain two neutral density filters to extend the dynamic range of the sensor and three spectral filters for narrowing effective double star magnitude difference.

Source record↗
NASA NTRS1990

Hubble Space Telescope: Optical telescope assembly handbook. Version 1.0

The Hubble Space Telescope is described along with how its design affects the images produced at the Science Instruments. An overview is presented of the hardware. Details are presented of the focal plane, throughput of the telescope, and the point spread function (image of an unresolved point source). Some detailed simulations are available of this, which might be useful to observers in planning their observations and in reducing their data.

Burrows, Chris↗