Final assembly and integration of the Orbiting Carbon Observatory instrument at the Jet Propulsion Laboratory in
Pasadena, California is now complete. The instrument was shipped to Orbital Sciences Corporation in March of this
year for integration with the spacecraft. This observatory will measure carbon dioxide and molecular oxygen absorption
to retrieve the total column carbon dioxide from a low Earth orbit. An overview of the design-driving science
requirements is presented. This paper then reviews some of the key challenges encountered in the development of the
sensor. Diffraction grating technology, lens assembly performance assessment, optical bench design for manufacture,
optical alignment and other issues specific to scene-coupled high-resolution grating spectrometers for this difficult
science retrieval are discussed.
The primary, secondary and tertiary mirrors of the Thirty Meter Telescope (TMT), taken together, have approximately
12,000 degrees of freedom in optical alignment. The Alignment and Phasing System (APS) will use
starlight and a variety of Shack-Hartmann based measurement techniques to position the segment pistons, tips,
and tilts, segment figures, secondary rigid body motion, secondary figure and the tertiary figure to correctly align
the TMT. We present a conceptual design of the APS including the requirements, alignment modes, predicted
performance, software architecture, and an optical design.
A novel space interferometer design originating in Europe has been studied. The interferometer uses the technique of
starlight nulling to enable detection of earth-like planets orbiting nearby stars. A set of four telescope spacecraft flying in
formation with a fifth, beam-combiner spacecraft forms the interferometer. This particular concept shows potential for
reducing the mission cost when compared with previous concepts by greatly reducing the complexity of the telescope
spacecraft. These spacecraft have no major deployable systems, have simplified propulsion and a more rugged
construction. The formation flying geometry provides for greater average separation between the spacecraft with
commensurate risk reduction. Key aspects of the design have been studied at the Jet Propulsion Laboratory with a view
to collaborations between NASA and the European Space Agency. An overview of the design study is presented with
some comparisons with the TPF-FFI concept.
The Laser Interferometer Space Antenna (LISA) optics model is used to simulate the propagation of a laser beam inside and between widely, five million kilometers, separated spacecraft moving in orbits about the sun. Numerical beam propagation models have been around for a long time. However, because of the somewhat extreme requirements on the model, namely very large distances while still requiring sub-picometer accuracies, a detailed exposition of the computational steps is necessary to ensure that the results are understood.
This note presents some of the optical modeling work performed at JPL and at Goddard in support of the Laser Interferometer Space Antenna (LISA) effort. The end-to-end optical model will be used to generate a synthetic data stream. The simulation will have the spacecraft moving in their respective orbits, with pointing of the spacecraft and station keeping about the proof masses accomplished using a control scheme, which minimizes the disturbance on the proof masses in the sensitive direction. The resulting data stream gives an indication of the magnitude of instrumental noise due to pointing jitter and motions of the spacecraft with respect to the proof masses. To reach this goal portions of the overall optical train have been modeled. Subsequent work will, as the modeling software and optical model evolve, combine these pieces into an integrated system.
The 2003 mission to Mars includes two Rovers, which will land on the Martian surface. Each Rover carries 9 cameras of 4 different designs. In addition, one similar camera is mounted to each lander assembly to monitor the descent and provide information for firing the control jets during landing. This paper will discuss the mechanical systems design of the cameras, including fabrication tolerances of the lenses, thermal issues, radiation shielding, planetary protection, detector mounting, electronics, the modularity achieved, and how the 10 different locations were accommodated on the very tight real estate of the Rovers and Landers.
In 2003, NASA is planning to send two robotic rover vehicles to explore the surface of Mars. The spacecraft will land on airbags in different, carefully chosen locations. The search for evidence indicating conditions favorable for past or present life will be a high priority. Each rover will carry a total of ten cameras of five various types. There will be a stereo pair of color panoramic cameras, a stereo pair of wide- field navigation cameras, one close-up camera on a movable arm, two stereo pairs of fisheye cameras for hazard avoidance, and one Sun sensor camera. This paper discusses the lenses for these cameras. Included are the specifications, design approaches, expected optical performances, prescriptions, and tolerances.
Narcissus is a stray light problem for infrared imaging sensors. Control of narcissus is a requirement for designing scanning sensors and narcissus analysis tools are available in some optical raytrace programs. These tools have not been optimized for staring sensors. Narcissus is assumed to be unimportant in staring array designs because the shading effects can be removed by offset correction of the detector array data. This would be sufficient for sensors which meet the following conditions: (1) calibrated at the entrance aperture, (2) operate at a constant optical housing temperature, (3) no movement of lenses for focus or change in field of view. Narcissus may be noticeable for sensors not meeting these conditions. We have developed procedures for applying existing narcissus analysis tools to staring sensors. A staring array prototype FLIR has been analyzed. Laboratory tests have confirmed the narcissus analysis.
BTDF at 3.39 microns was measured on ZnSe substrates and on substrates with 1/2, 2/3, and full multilayer coatings. BRDF at 3.39 microns was also measured on Ge substrates with multilayer coatings. The BTDF and BRDF range for coated samples overlaps the range for the uncoated substrates.