A Scientific Assessment of a New Technology Orbital Telescope (1995) / Chapter Skim
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4 ASTRONOMICAL TECHNOLOGY DEMONSTRATIONS
4 ASTRONOMICAL TECHNOLOGY DEMONSTRATIONS
Pages 40-46
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From page 40... ...
DEMONSTRATIONS DURING THE BASELINE MISSION Use of Active Optics The most fundamental demonstration for astronomical purposes is to show that large mirrors can be refigured on orbit. The ability to sense a wavefront and close the feedback loop to control the shape of the mirror is critical to using the ATD/NTOT's technology in future astronomical missions.
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From page 41... ...
The quality of the images must be evaluated under a variety of conditions, including various positions in the field of view that can be reached through the fast steering mirror and a variety of thermal conditions. To explore the effects of thermal environment, the image quality should be studied under a variety of orbital configurations.
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From page 42... ...
A 4-meter space telescope in a Molniya orbit could observe occultations inaccessible to ground-based observatories or telescopes in low Earth orbit, greatly increasing the potential application of the occultation technique. Successful demonstration that an orbiting telescope could be maneuvered to record occultations unobservable from Earth would open the way for comprehensive investigations of the occultations of virtually any chosen body in the solar system (including the possibility of measuring diameters of Kuiper Disk objects)
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From page 43... ...
Thus, occultation data recording rates are typically 10 to 50 Hz, and the recording should be synchronized with absolute time and spacecraft position. Since the high-speed array detectors planned for the military mission would provide simultaneous occultation light curves at visible and infrared wavelengths at these rates, no special changes to the baseline plan appear to be necessary for this astronomical technology demonstration other than the on-orbit maneuverability.
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From page 44... ...
These additional sources include the tracking system, the fluctuating thermal load, the varying field distortion as the fast steering mirror moves the field, and so on. The addition of an optical framing camera would lead to significant additional information about the performance of the telescope.
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From page 45... ...
Enhanced cooling of the InSb array, required for sky-limited astronomical performance, might be an important addition for evaluating the thermal performance of the system if the telescope and its optics are allowed to cool to a sufficiently low temperature. Field Distortion Stability The addition of an astronomical framing camera would allow several additional measurements that are related directly to the astronomical projects discussed in Chapter 5 and that also can demonstrate stability of the field, or at least the ability to calibrate the distortions.
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From page 46... ...
A program to test the photometric stability over time scales from milliseconds to months is an excellent test of the ATD/NTOT's technological capability for astronomical applications. If the photometry is found to be precise and stable, surveys of oscillating stars may become a feasible science project to consider for an extended mission.
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