The ISS as a Testbed for Future Large Astronomical Observatories: The OpTIIX Demonstration Program
No abstract available
laser metrology↗
Engineering topics
Callen, P.
Publications and source records attributed to Callen, P..
The ISS as a Testbed for Future Large Astronomical Observatories: The OpTIIX Demonstration Program
Future large (diameters in excess of approx. 10 m) astronomical observatories in space will need to employ advanced technologies if they are to be affordable. Many of these technologies are ready to be validated on orbit and the International Space Station (ISS) provides a suitable platform for such demonstrations. These technologies include low-cost, low-density, highly deformable mirror segments, coupled with advanced sensing and control methods. In addition, the ISS offers available telerobotic assembly techniques to build an optical testbed that embodies this new cost-effective approach to assemble and achieve diffraction-limited optical performance for very large space telescopes. Given the importance that NASA attaches to the recommendations of the National Academy of Sciences "Decadal Survey" process, essential capabilities and technologies will be demonstrated well in advance of the next Survey, which commences in 2019. To achieve this objective, the Jet Propulsion Laboratory (JPL), NASA Johnson Space Center (JSC), NASA Goddard Space Flight Center (GSFC), and the Space Telescope Science Institute (STScI) are carrying out a Phase A/B study of the Optical Testbed and Integration on ISS eXperiment (OpTIIX). The overarching goal is to demonstrate well before the end of this decade key capabilities intended to enable very large optical systems in the decade of the 2020s. Such a demonstration will retire technical risk in the assembly, alignment, calibration, and operation of future space observatories. The OpTIIX system, as currently designed, is a six-hexagon element, segmented visual-wavelength telescope with an edge-to-edge aperture of 1.4 m, operating at its diffraction limit,
Burdick, G.↗
The Atmosphere Explorer power subsystem
The design and operation of the power subsystem for the Atmospheric Explorer spacecraft are discussed. The additional functional redundancy which was added in several component areas to improve the overall subsystem reliability is analyzed. The battery charging technique has been modified to include third electrode overcharge control. The automatic removal of all battery charge is provided to correct abnormally high battery voltages. An undervoltage detector has been added which removes all nonessential spacecraft loads when the battery voltage falls below a given level. All automatic functions can be over-ridden by ground command.
Obenschain, A.↗
The Atmosphere Explorer power subsystem
The present work describes the design and in-flight performance of the power subsystem for the first three Atmosphere Explorer (AE) spacecraft. The subsystem provides all electrical power to the spacecraft loads and consists of a solar array, three batteries, and a power supply electronics unit. Power from the solar array is supplied to the spacecraft loads through an unregulated power bus, which varies between -26 and -38 V. Loads which are normally on only during data collection phases of an orbit are fed from a tightly regulated -24.5 V bus. Power subsystem performance during the first three months in orbit has been nominal, except for an anomally in the shunt limiter protection circuitry. A malfunctioning shunt control amplifier was reconnected via ground command.
Obenschain, A.↗