James Webb Space Telescope (JWST) Observatory architecture and performance

Nella, John; Atcheson, Paul D.; Atkinson, Charles B.; Au, Doug; Bronowicki, Allen J.; Bujanda, Ed; Cohen, A.; Davies, Don; Lightsey, Paul A.; Lynch, Richard J.M.; Lundquist, Ray; Menzel, Michael T.; Mohan, M.; Pohner, John; Reynolds, P. T.; Rivera, H.; Texter, S.; Shuckstes, David V.; Simmons, Debra D. Fitzgerald; Smith, Robert C.; Sullivan, Pamela C.; Waldie, Dean D.; Woods, Robert A.

doi:10.1117/12.548928

Cited by 41 publications

(19 citation statements)

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“…We assumed a telescope and sun shade temperature T JWST of 45 K with an emissivity of = 0.15 (Belu et al 2011) and a total emitting surface of sun shade and mirror combined of A E = 240 m 2 (Nella et al 2002). The number of pixels n px was calculated to be…”

Section: Discussionmentioning

confidence: 99%

Spectroscopic characterization of the atmospheres of potentially habitable planets: GL 581 d as a model case study

Paris¹,

Cabrera²,

Godolt³

et al. 2011

A&A

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Context. Were a potentially habitable planet to be discovered, the next step would be the search for an atmosphere and its characterization. Eventually, surface conditions, hence habitability, and biomarkers as indicators for life would be assessed. Aims. The super-Earth candidate Gliese (GL) 581 d is the first potentially habitable extrasolar planet so far discovered. Therefore, GL 581 d is used to illustrate a hypothetical detailed spectroscopic characterization of such planets. Methods. Atmospheric profiles for a wide range of possible one-dimensional (1D) radiative-convective model scenarios of GL 581 d were used to calculate high-resolution synthetic emission and transmission spectra. Atmospheres were assumed to be composed of N 2 , CO 2 , and H 2 O. From the spectra, signal-to-noise ratios (SNRs) were calculated for a telescope such as the planned James Webb Space Telescope (JWST). Exposure times were set to be equal to the duration of one transit. Results. The presence of the model atmospheres can be clearly inferred from the calculated synthetic spectra thanks to strong water and carbon-dioxide absorption bands. Surface temperatures can be inferred for model scenarios with optically thin spectral windows. Dense, CO 2 -rich (potentially habitable) scenarios do not enable us to determine the surface temperatures nor assess habitability. Degeneracies between CO 2 concentration and surface pressure complicate the interpretation of the calculated spectra, hence the determination of atmospheric conditions. Still, inferring approximative CO 2 concentrations and surface pressures is possible. In practice, detecting atmospheric signals is challenging because the calculated SNR values are well below unity in most of the cases. The SNR for a single transit was only barely larger than unity in some near-IR bands for transmission spectroscopy. Most interestingly, the false-positive detection of biomarker candidates such as methane and ozone might be possible in low resolution spectra because CO 2 absorption bands overlap biomarker spectral bands. This can be avoided, however, by observing all main CO 2 IR bands instead of concentrating on, e.g., the 4.3 or 15 μm bands only. Furthermore, a masking of ozone signatures by CO 2 absorption bands is shown to be possible. Simulations imply that such a false-negative detection of ozone would be possible even for rather high ozone concentrations of up to 10 −5 .

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Section: Discussionmentioning

confidence: 99%

Spectroscopic characterization of the atmospheres of potentially habitable planets: GL 581 d as a model case study

Paris¹,

Cabrera²,

Godolt³

et al. 2011

A&A

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show abstract

“…This CAD database is then used to create the TSS surface models and PATRAN finite element models. The thermal environment of the JWST observatory is partially determined by the observatory pitch angle [6] resulting in an observatory thermal map upon running the TSS/SINDA analysis. This thermal map is then applied to the structural model using PATRAN.…”

Section: Capabilities Of Nimosmentioning

confidence: 99%

Optical performance assessment under environmental and mechanical perturbations in large, deployable telescopes

Folley

Bronowicki

2005

SPIE Proceedings

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Prediction of optical performance for large, deployable telescopes under environmental conditions and mechanical disturbances is a crucial part of the design verification process of such instruments for all phases of design and operation: ground testing, commissioning, and on-orbit operation. A Structural-Thermal-Optical-Performance (STOP) analysis methodology is often created that integrates the output of one analysis with the input of another. The integration of thermal environment predictions with structural models is relatively well understood, while the integration of structural deformation results into optical analysis/design software is less straightforward. A Matlab ® toolbox has been created that effectively integrates the predictions of mechanical deformations on optical elements generated by, for example, finite element analysis, and computes optical path differences for the distorted prescription. The engine of the toolbox is the real ray-tracing algorithm that allows the optical surfaces to be defined in a single, global coordinate system thereby allowing automatic alignment of the mechanical coordinate system with the optical coordinate system. Therefore, the physical location of the optical surfaces is identical in the optical prescription and the finite element model. The application of rigid body displacements to optical surfaces, however, is more general than for use solely in STOP analysis, such as the analysis of misalignments during the commissioning process. Furthermore, all the functionality of Matlab ® is available for optimization and control. Since this is a new tool for use on flight programs, it has been verified against CODE V. The toolbox' functionality, to date, is described, verification results are presented, and, as an example of its utility, results of a thermal distortion analysis are presented using the James Webb Space Telescope (JWST) prescription.

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“…The introduction of phase diversity [8], which has been widely applied to image recovering such as Hubble Space Telescope imaging [9], makes phase retrieval more efficient, robust, and accurate. The Modified Gerchberg-Saxton (MGS) algorithm [10] proposed by Jet Propulsion Laboratory (JPL) is the most representative PDPR algorithm which has been used in JWST [2,3,11]. Since GS algorithm cannot retrieve a real wavefront when the peak-to-valley (PV) value of objective phase exceeds 2π , it is necessary to add a phase unwrapping process to improve the dynamic range of these phase retrieval algorithm in MGS.…”

Section: Introductionmentioning

confidence: 99%

“…By using a point source of light, phase retrieval can be used for high precision wavefront sensing for optical imaging systems. This method has been proposed to realize diffraction-limitation imaging for the next generation telescope [2,3,11], such as Webb Space Telescope [2]. It has many advantages in wavefront sensing, such as high accuracy and simplicity compared to other technique such as Shack-Hartmann sensor [3].…”

Section: Introductionmentioning

confidence: 99%

Improved phase retrieval algorithm for optical imaging systems

Qin

Dong

et al. 2013

International Symposium on Photoelectronic Detection and Imaging 2013: Laser Sensing and Imaging and Applications

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The Modified Hybrid-Input-Output (MHIO) phase retrieval algorithm is proposed for wavefront sensing. The resultsshow that the MHIO algorithm significantly outperforms the Modified Gerchberg-Saxton algorithm (MGS) in large noise. However its dynamic-range is lower than MGS algorithm. It also shows that if combine the MGS algorithm with MHIO algorithm, which is called MGS+MHIO algorithm, then it can retain the property of MGS's high dynamic-range and MHIO's accuracy so that outperforms either MGS or MHIO algorithm. Repeating simulation results show that MGS+MHIO algorithm improves RMS of phase error obviously in high dynamic range and large noise.

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James Webb Space Telescope (JWST) Observatory architecture and performance

Cited by 41 publications

References 0 publications

Spectroscopic characterization of the atmospheres of potentially habitable planets: GL 581 d as a model case study

Spectroscopic characterization of the atmospheres of potentially habitable planets: GL 581 d as a model case study

Optical performance assessment under environmental and mechanical perturbations in large, deployable telescopes

Improved phase retrieval algorithm for optical imaging systems

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