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This paper reports on the development, manufacture and integration of the James Webb Space Telescope’s sunshield and spacecraft. Both of these JWST elements have completed design and development testing. This paper will review basic architecture and roles of these systems. Also to be presented is the current state of manufacture, assembly integration and test. This paper will conclude with a look at the road ahead for each subsystem prior to integration with the integrated telescope and instrument elements at Northrop Grumman’s Space Park facility in late 2017.

As a part of the Joint Polar Satellite System (JPSS, formerly the NPOESS afternoon orbit), the instruments Cross-track Infrared Sounder (CrIS) and Advanced Technology Microwave Sounder (ATMS) make up the Cross-track Infrared and Microwave Sounder Suite (CrIMSS). CrIMSS will primarily provide global temperature, moisture, and pressure profiles and calibrated radiances [1]. In preparation for the NPP launch in 2011, we have ported and tested the operational CrIMSS Environmental Data Record (EDR) algorithms using both synthetic and proxy data generated from the IASI, AMSU, MHS data from Metop-A satellite.

The James Web Space Telescope (JWST) is a large, infrared-optimized space telescope scheduled for launch in 2014. System-level verification of critical performance requirements will rely on integrated observatory models that predict the wavefront error accurately enough to verify that allocated top-level wavefront error of 150 nm root-mean-squared (rms) through to the wave-front sensor focal plane is met. This paper describes the systems engineering approach used on the JWST through the detailed design phase.

JWST will be used to help understand the shape and chemical composition of the universe, and the evolution of galaxies, stars and planets. With a 6.5 meter primary mirror, the Observatory will observe red shifted light from the early history of the universe, and will see objects 400 times fainter than those seen from large ground-based telescopes or the current generation of space-based infrared telescopes. NASA Goddard Space Flight Center (GSFC) manages JWST with contributions from a number of academic, government, and industrial partners. The contract to build the space-based Observatory for JWST was awarded to the Northrop Grumman Space Technology (NGST)/Ball/Kodak/ATK team.

The Cross-track Infrared and Microwave Sounder Suite (CrIMSS) consists of a microwave radiometer and an infrared interferometer and is scheduled to fly on the NPP and NPOESS satellites. The sensors are designed for the accurate measurement of atmospheric pressure, temperature and moisture profiles. This paper presents an overview of the CrIMSS sensors and the retrieval algorithm. Validation of the algorithm with current satellite sounder data will also be presented.

As more and more high-resolution FTIR instruments planned for future satellite remote sensing, robust and fast physical retrieval algorithms are needed to invert the measured radiances to geophysical parameters. One of the important components of a physical retrieval algorithm is the fast forward model. For interferometer-based sounders, the Sensor Response function (SRF) may not be localized. A fast and accurate forward model, Optimal Spectral Sampling (OSS), is used to calculate upwelling radiances in our physical retrieval algorithm. It's capable of modeling radiance spectra with either a localized or a non-localized SRF with negative side lobes. Derivatives with respect to atmospheric and surface properties can be calculated analytically and efficiently. The OSS fast RT model is idea for atmospheric sounding or atmospheric compensation applications. The inversion method is based on an optimal estimation algorithm. Empirical Orthogonal Functions (EOF) are used to transform the atmospheric profiles into more compact form for fast and stable inversions. The non-linearity of the radiative transfer function is taken into account in the algorithm so the inversion is very robust. The algorithm has been used to simulate the Environmental Data Record (EDR) retrieval performance for the Cross-track Infrared Sounder (CrIS). We extended the method to model cloud directly. The cloud parameters are retrieved simultaneously with the atmospheric and surface parameters. This algorithm has been successfully applied to the NPOESS Aircraft Sounder Testbed (NAST-I) measured radiances.