Search NASA⌕ Search

SEARCH · Search NASA

Results for “Webb”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Model-Based Thermal System Design Optimization for the James Webb Space Telescope

Spacecraft thermal model validation is normally performed by comparing model predictions with thermal test data and reducing their discrepancies to meet the mission requirements. Based on thermal engineering expertise, the model input parameters are adjusted to tune the model output response to the test data. The end result is not guaranteed to be the best solution in terms of reduced discrepancy and the process requires months to complete. A model-based methodology was developed to perform the validation process in a fully automated fashion and provide mathematical bases to the search for the optimal parameter set that minimizes the discrepancies between model and data. The methodology was successfully applied to several thermal subsystems of the James Webb Space Telescope (JWST). Global or quasiglobal optimal solutions were found and the total execution time of the model validation process was reduced to about two weeks. The model sensitivities to the parameters, which are required to solve the optimization problem, can be calculated automatically before the test begins and provide a library for sensitivity studies. This methodology represents a crucial commodity when testing complex, large-scale systems under time and budget constraints. Here, results for the JWST Core thermal system will be presented in detail.

Cataldo, Giuseppe↗
NASA NTRS2016

Stray Light Modeling of the James Webb Space Telescope (JWST) Integrated Science Instrument Module (ISIM)

This paper describes an integrated stray light model of each Science Instrument (SI) in the Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST) and the Optical Telescope Element Simulator (OSIM), the light source used to characterize the performance of ISIM in cryogenic-vacuum tests at the Goddard Space Flight Center (GSFC). We present three cases where this stray light model was integral to solving questions that arose during the testing campaign - 1) ghosting and coherent diffraction from hardware surfaces in the Near Infrared Imager and Slitless Spectrograph (NIRISS) GR700XD grism mode, 2) ghost spots in the Near Infrared Camera (NIRCam) GRISM modes, and 3) scattering from knife edges of the NIRCam focal plane array masks.

stray light modeling↗
NASA NTRS2018

Breaking the Cost Curve: Applying Lessons Learned from the James Webb Space Telescope Development to Build More Cost-Effective Large Space Telescopes in the Future

This paper looks at the key programmatic and technical drivers of the James Webb Space Telescope and assesses ways to building more cost-effective telescopes in the future. The paper evaluates the top level programmatics for JWST along with the key technical drivers from design through integration and testing. Actual data and metrics from JWST are studied to identify what ultimately drove cost on JWST. Finally, the paper assesses areas where applying lessons learned can reduce costs on future observatories and will provide better insights into critical areas to optimize for cost.

ATLAST↗
NASA NTRS2018

The James Webb Space Telescope: Observatory Status and Preparations for Launch

The James Webb Space Telescope (JWST) is a large (6.5 meter) segmented aperture telescope equipped with near- and mid-infrared instruments (0.6-28 microns), all of which are passively cooled to approximately 40 degrees Kelvin by a 5-layer sunshield while the mid-infrared instrument is actively cooled to 7 degrees Kelvin. The JWST telescope recently completed its cryogenic test program and the sunshield has been fully integrated and deployed. JWST is currently in the final stages of the test program at the Observatory level. The current estimated JWST performance metrics will be presented, such as the image quality, pointing stability, sensitivity, and stray light backgrounds. The JWST development status and future plans will be described for the final testing, launch, and commissioning.

McElwain, Michael↗
NASA NTRS2018

Performance of the Center-Of-Curvature Optical Assembly During Cryogenic Testing of the James Webb Space Telescope

Cryogenic testing of the James Webb Space Telescope (JWST) included center-of-curvature metrology of the 18-segment primary mirror (PM). The Center-of-Curvature Optical Assembly (COCOA) consisted of a multiple-wavelength interferometer, a reflective null, coarse and fine alignment systems, and two displacement measuring interferometer systems. The COCOA enabled alignment and phasing of the segments from millimeter-level errors down to the nanometer level. This paper describes the COCOA, the test setup, the testing performed, and the performance of the COCOA in aligning the PM segments and measuring the final PM wavefront error.

Hadaway, James↗
NASA NTRS2017

Observing Exoplanets with the James Webb Space Telescope

The census of exoplanets has revealed an enormous variety of planets or- biting stars of all ages and spectral types: planets in orbits of less than a day to frigid worlds in orbits over 100 AU; planets with masses 10 times that of Jupiter to planets with masses less than that of Earth; searingly hot planets to temperate planets in the Habitable Zone. The challenge of the coming decade is to move from demography to physical characterization. The James Webb Space Telescope (JWST) is poised to open a revolutionary new phase in our understanding of exoplanets with transit spectroscopy of relatively short period planets and coronagraphic imaging of ones with wide separations from their host stars. This article discusses the wide variety of exoplanet opportunities enabled by JWSTs sensitivity and stability, its high angular resolution, and its suite of powerful instruments. These capabilities will advance our understanding of planet formation, brown dwarfs, and the atmospheres of young to mature planets.

Beichman, Charles A.↗
NASA NTRS2018

Thermal Model Performance for the James Webb Space Telescope OTIS Cryo-Vacuum Test

The James Webb Space Telescope (JWST), set to launch in mid-2020, 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, has recently been completed 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 system-level pre-test thermal model was constructed which fully captured the behavior of the payload, ground support equipment, and surrounding test chamber. This thermal model simulated both the transient cooldown to and warmup from a 20 K flight-like environment, as well as predicted the payload performance at cryo-stable conditions. The current work is an assessment of thermal model pre-test prediction performance against actual payload response during the OTIS CV test. Overall, the thermal model performed exceedingly well at predicting schedule and payload response. Looking in depth, this work examines both the benefits and shortcomings of assumptions made pre-test to simplify model execution when compared against test data. It explores in detail the role of temperature-dependent emissivities during transition to cryogenic temperatures, as well as the impact that model geometry simplifications have on tracking of critical hardware limits and constraints. This work concludes with a list of recommendations to improve the accuracy of thermal modeling for future large cryogenic tests. The insight gained from the OTIS CV test thermal modeling will benefit planning and execution for upcoming cryogenic missions.

Testing↗
NASA NTRS2018

Thermal Model Performance for the James Webb Space Telescope OTIS Cryo-Vacuum Test

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, has recently been completed 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 system-level pre-test thermal model was constructed which fully captured the behavior of the payload, ground support equipment, and surrounding test chamber. This thermal model simulated both the transient cooldown to and warmup from a 20K flight-like environment, as well as predicted the payload performance at cryo-stable conditions. The current work is a preliminary assessment of thermal model performance against actual payload response during the OTIS CV test. It examines both the benefits and shortcomings of assumptions made pre-test to simplify model execution when compared against test data. It explores in detail the role of temperature-dependent emissivities during transition to cryogenic temperatures, as well as the impact that model geometry simplifications have on tracking of critical hardware limits and constraints. This work concludes with a list of recommendations to improve the accuracy of thermal modeling for future large cryogenic tests. It is hoped that the insight gained from the OTIS CV test thermal modeling will benefit planning and execution for upcoming cryogenic missions.

JWST↗
NASA NTRS2018

Mission Configuration Tree for the James Webb Space Telescope (JWST)

The GSFC Mission Configuration web-based application is a means of documenting the structure of the many elements used in building each mission that NASA launches, as well as archiving the documents associated with each of these elements and keeping track of suppliers. This includes all available drawings, engineering orders, parts lists, block diagrams, and photos of each system, subsystem, and component. While the information for several of NASA's missions is being input into Mission Configuration, the ten weeks of this project focused on collecting information for the instrument systems of the James Webb Space Telescope. Documents were collected from a database called the Next Generation Integrated Network (NGIN) so that they can eventually be uploaded into the application. From these documents, including drawings and parts lists, a configuration tree was created in Microsoft Visio which showed the relationships between each system, subsystem, and component. When both these documents and the configuration tree are input into Mission Configuration, they will be place into a drill down tree structure, from which drawings and documents can be accessed directly. Mission Configuration also includes search functions that make all parts searchable by keywords such as vendor, part number, taxonomy, and alternate nomenclature. This application is an important resource for providing access to documents related to the components used on each mission. It has created a central repository for information which can be used to benefit Safety & Mission Assurance, but may also be useful across codes. The process of collecting the information and documents to put into Mission Configuration is also allowing for a concise breakdown of information from diverse formats, creating standardization which makes information more readily accessible, while retaining project-specific information that makes it more easily searchable.

Cain, Mary C.↗
NASA NTRS2018

Thermal Model Performance for the James Webb Space Telescope OTIS Cryo-Vacuum Test

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, has recently been completed 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 system-level pre-test thermal model was constructed which fully captured the behavior of the payload, ground support equipment, and surrounding test chamber. This thermal model simulated both the transient cooldown to and warmup from a 20K flight-like environment, as well as predicted the payload performance at cryo-stable conditions. The current work is a preliminary assessment of thermal model performance against actual payload response during the OTIS CV test. Overall, the thermal model performed exceedingly well at predicting schedule and payload response. Looking in depth, this work examines both the benefits and shortcomings of assumptions made pre-test to simplify model execution when compared against test data. It explores in detail the role of temperature-dependent emissivities during transition to cryogenic temperatures, as well as the impact that model geometry simplifications have on tracking of critical hardware limits and constraints. This work concludes with a list of recommendations to improve the accuracy of thermal modeling for future large cryogenic tests. It is hoped that the insight gained from the OTIS CV test thermal modeling will benefit planning and execution for upcoming cryogenic missions.

Yang, Kan↗
NASA NTRS2018

Creating the Required Deep Space Environments for Testing the James Webb Space Telescope (JWST) at NASA Johnson Space Center's Chamber A

NASA is the mission lead for the James Webb Space Telescope (JWST), the next of the "Great Observatories", scheduled for launch in 2021. NASA was directly responsible for the integration and test (I&T) program that culminated in an end-to-end cryo vacuum optical test of the flight telescope and instrument module in Chamber A at NASA Johnson Space Center. Historic Chamber A is the largest thermal vacuum chamber at Johnson Space Center and one of the largest space simulation chambers in the world. Chamber A has undergone a major modernization effort to support the deep cryogenic, vacuum and cleanliness requirements for testing the JWST. This paper will discuss the thermal vacuum test of the Optical Telescope Element (OTE) plus Integrated Science Instrument Module (ISIM) (OTIS) as well as the extensive series of tests that were performed to incrementally validate the operations and performance of the Chamber and Ground Support Equipment (GSE). Each test required a unique thermal vacuum profile for cool down and warm up, steady state operations, GSE testing and contamination control. Select results will be presented on Facility Functional Testing, Chamber Bake-out, GSE Cryo-Proof Testing, Chamber Commissioning, the Optical Ground Support Equipment (OGSE) Test series and the final thermal vacuum test of the OTIS with respect to facility operations to meet JWST program test requirements.

Francis, Andrew↗
NASA NTRS2018

Modernization of NASA Johnson Space Center's Chamber A to Support Cryogenic Vacuum Optical Testing of the James Webb Space Telescope (JWST)

Final document is attached. NASA is the mission lead for the James Webb Space Telescope (JWST), the next of the "Great Observatories", scheduled for launch in 2021. NASA is directly responsible for the integration and test (I&T) program that culminated in an end-to-end cryo vacuum optical test of the flight telescope and instrument module in Chamber A at NASA Johnson Space Center. Historic Chamber A is the largest thermal vacuum chamber at Johnson Space Center and one of the largest space simulation chambers in the world. Chamber A has undergone a major modernization effort to support the deep cryogenic, vacuum and cleanliness requirements for testing the JWST. This paper describes the upgrades to the Chamber A facility: Thermal Shrouds, Helium Refrigeration, Liquid Nitrogen System, High Vacuum System, Clean Airflow System, and Utilities.

Thermal vacuum testing↗
NASA NTRS2018

Refurbishment of NASA's Johnson Space Center Liquid Nitrogen Bulk Storage Tanks in Preparation for Thermal Vacuum Optical Testing of the James Webb Space Telescope (JWST)

NASA is the mission lead for the James Webb Space Telescope (JWST), the next of the "Great Observatories", scheduled for launch in 2019. It is directly responsible for the integration and test (I&T) program that culminated in an end-to-end cryo vacuum optical test of the flight telescope and instrument module in Chamber A at NASA Johnson Space Center. Historic Chamber A is the largest thermal vacuum chamber at Johnson Space Center and one of the largest space simulation chambers in the world. Chamber A has undergone a major modernization effort to support the deep cryogenic, vacuum and cleanliness requirements for testing the JWST. Chamber A utilizes Liquid Nitrogen as a thermal barrier between the 300 Kelvin vessel wall and the 20 Kelvin helium environmental conditioning shrouds. The 155,000 gallon capacity of the six vessels support long duration testing which support low and deep space simulations for today's testing. This paper describe the challenges of refurbishing six liquid nitrogen bulk storage vessels that are 60 year old. The vessels were refurbished in place and focused primarily on the vacuum annulus. The challenges of vessel research, design engineering and project management will be discussed. The refurbishment of the vessels has extended the life of the vessels for another 35-50 years on the vacuum annulus integrity. The survivability of the bulk storage vessels was tested during the historic hurricane Harvey of 2017 during the 100 day JWST thermal-vacuum test.

Garcia, Sammy↗
NASA NTRS2019

Breaking the Cost Curve: Applying Lessons Learned from the James Webb Space Telescope Development

This paper looks at the key programmatic and technical drivers of the James Webb Space Telescope and assesses ways to building more cost-effective telescopes in the future. The paper evaluates the top level programmatics for JWST along with the key technical drivers from design through integration and testing. Actual data and metrics from JWST are studied to identify what ultimately drove cost on JWST. Finally, the paper assesses areas where applying lessons learned can reduce costs on future observatories and will provide better insights into critical areas to optimize for cost.

Feinberg, Lee↗
NASA NTRS2018

James Webb Space Telescope (JWST) Optical Telescope Element and Integrated Science Instrument Module (OTIS) Cryogenic Test Program and Results

In 2017, the James Webb Space Telescope Optical Telescope Element and Integrated Science Instrument Module (OTIS) underwent cryogenic optical testing at the Johnson Space Center. In this paper, we summarize the successful execution and results of this 100-day test, which was a major program milestone. We summarize the as-run test configuration and provide a top-level as-run timeline. We also provide the top-level functional, optical, thermal, and operational results from the test. We summarize the key technical issues encountered and the resolution of those issues. The results of the OTIS test indicate that the payload should be fully capable of delivering on JWST's exciting scientific potential.

Kimble, Randy A.↗
NASA NTRS2019

L2 Station Keeping Maneuver Strategy for the James Webb Space Telescope

The station-keeping plan for the James Webb Space Telescope is zero velocity in the x-component at the fourth successive crossing of the XZ plane of the rotation libration point frame. A differential corrector is employed to determine the necessary delta-v. Maneuvering along the position component of the stable eigenvector of the monodromy matrix produces a minimum delta-v solution. The techniques developed to determine the minimum maneuver direction in a full ephemeris model, along with strategies to cope with the attitude constraints imposed by the sunshield that prevents the ability to maneuver along the stable eigenvector, are examined in this study.

Libration Point Orbit↗
NASA NTRS2019

Libration Orbit Eclipse Avoidance Maneuver Study for the James Webb Space Telescope Mission

Mission analysis of libration orbit trajectories at Sun-Earth/Moon L2 typically includes predictions of lunar and Earth eclipses during the mission life-time. The NASA James Webb Space Telescope (JWST) trajectory, by design, avoids these eclipses by pruning its launch window. In an off-nominal scenario where an eclipse is predicted, a maneuver strategy is needed. In this paper, trade studies are examined for JWST that characterize the burn magnitude, location, and epochs of multiple maneuver plans to avoid an eclipse. The results enable analysts to explore the space of feasible maneuver strategies during routine operations.

Maneuver design↗