NIRCam is a highly sensitive, multi-spectral, high-resolution, cryogenic, compact, light-weight, and rugged near infra-red camera on the James Webb Space Telescope. The successful development of NIRCam is aided by good system engineering practice. This is a discussion of important elements of NIRCam System Engineering with some light-hearted contrast to a more common activity.
The James Webb Space Telescope (JWST) Observatory, the follow-on mission to the Hubble Space Telescope and to the Spitzer Space Facility, will yield astounding breakthroughs in the realms of infrared space science. The science instrument suite for this Observatory will consist of a Near-Infrared Camera, a Near-Infrared Spectrograph, a Mid-Infrared Instrument with imager, coronagraph and integral field spectroscopy modes, and a Fine Guider System Instrument with both a Guider module and a Tunable Filter Module. In this paper we present an overview of the optical designs of the telescope and instruments.
NASA and the FAA have expressed interest in laser radar's capabilities to detect wind profiles at altitude. A number of programs have been addressing the technical feasibility and utility of laser radar atmospheric backscatter data to determine wind profiles and wind hazards for aircraft guidance and navigation. In addition, the U.S. Air Force is investigating the use of airborne lidar to achieve precision air drop capability, and to increase the accuracy of the AC- 130 gunship and the B-52 bomber by measuring the wind field from the aircraft to the ground. There are emerging capabilities of airborne laser radar to measure wind velocities and detect turbulence and other atmospheric disturbances out in front of an aircraft in real time. The measurement of these parameters can significantly increase fuel efficiency, flight safety, airframe lifetime, and terminal area capacity for new and existing aircraft. This is achieved through wind velocity detection, turbulence avoidance, active control utilization to alleviate gust loading, and detection of wingtip wake vortices produced by landing aircraft. This paper presents the first flight test results of an all solid-state 2-micrometers laser radar system measuring the wind field profile 1 to 2 km in front of an aircraft in real time. We find 0.7-m/s wind measurement accuracy for the system which is configured in a rugged, light weight, high- performance ARINC package.
This paper focuses on the determination of cleanliness levels the contamination control plan and highlights of how the plan was implemented through the build and test of the CLAES instrument. The hardware development addressed both molecular and particulate contamination concerns however this paper will concentrate on particulate contamination because of its greater impact on CLAES performance. A primary noise source is off axis scatter from the earth surface. The stratospheric altitude of interest is 10 to 60 kilometers resulting in low altitude detetion of only 0. 2 degrees above the hard earth surface. This necessitated careful attention to straylight controls throughout the design fabrication assembly and ground test of the instrument. 2.
The CLAES is calibrated with a full-aperture blackbody on the instrument-aperture door. In laboratory calibration, the blackbody is resistively heated. On orbit, the blackbody is intended to be heated by exposure to radiation from the earth while the door is open; calibration data are then taken at several temperatures after closing the door, as the blackbody cools to the temperature of the instrument's cryogenic telescope. An analysis of radiometric calibration-source accuracy is shown, indicating a nominal value of 2.7 percent at 12.63 microns. Preliminary analysis of calibration data indicates a measurement repeatability of about 1.25 percent. Details of the blackbody design, construction, and thermal instrumentation are given.