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Proceedings Paper

Imaging planets about other stars with UMBRAS: target acquisition and station keeping
Author(s): Helen M. Hart; Ian J.E. Jordan; Alfred B. Schultz; John L. Hershey; Mark Kochte; Forrest C. Hamilton; Dorothy A. Fraquelli; Daniel J. Schroeder; Fred Bruhweiler; Mike A. DiSanti; Cherie L. Miskey; Bruce Johnson; M. S. Fadali; Melodi Rodrigue; K. P. Cheng; R. Clark
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Paper Abstract

We present a novel coronagraphic imaging technique and design for space-based telescopes. The Umbral Mission Blocking Radiating Astronomical Sources (UMBRAS) is a space mission design consisting of a free flying occulter, the Solar Powered Ion Driven Eclipsing Rover (SPIDER), and possibly one or two metrology platforms. The UMBRAS spacecraft operate in conjunction with a space-based telescope. The size of the occulting SPIDER is dictated by the size of the telescope with which it will work. The goal of UMBRAS is to provide "paleolithic" (i.e., non-focal plane) coronagraphic capability to enable direct imaging of extrasolar Jovian planets and other bright substellar companions such as brown dwarfs. We discuss two aspects of the operation of a free flying occulter: acquisition of targets and station keeping. Target acquisition is modeled after the onboard schemes used by Hubble Space Telescope (HST) science instruments. For UMBRAS, the onboard commanding sequences would include imaging the field using instruments on the telescope, locating the target and the occulter in the field, and accurately positioning the occulter over the target. Station keeping consists of actively maintaining the occulter position in the telescope line of sight to the target. Velocity matching of the c)cculter with the space-based telescope is essential to mission performance. An appropriate combination of solar electric and cold gas thrusters provide the ability to match velocities using position information derived from communication and from ranging data between telescope, occulter and any metrology stations. The accuracy requirements for target acquisition and station keeping depend upon the science requirements, the occultation geometry, and the sensitivity of the science to changes in occultation geometry during an exposure sequence. Observing modes other than the ideal centered occultation of a target will be discussed.

Paper Details

Date Published: 15 December 2000
PDF: 11 pages
Proc. SPIE 4087, Applications of Photonic Technology 4, (15 December 2000); doi: 10.1117/12.406339
Show Author Affiliations
Helen M. Hart, Computer Sciences Corp. (United States)
Ian J.E. Jordan, Computer Sciences Corp. (United States)
Alfred B. Schultz, Computer Sciences Corp. (United States)
John L. Hershey, Computer Sciences Corp. (United States)
Mark Kochte, Computer Sciences Corp. (United States)
Forrest C. Hamilton, Computer Sciences Corp. (United States)
Dorothy A. Fraquelli, Computer Sciences Corp. (United States)
Daniel J. Schroeder, Beloit College (United States)
Fred Bruhweiler, Catholic Univ. of America (United States)
Mike A. DiSanti, Catholic Univ. of America (United States)
Cherie L. Miskey, Catholic Univ. of America (United States)
Bruce Johnson, Univ. of Nevada (United States)
M. S. Fadali, Univ. of Nevada (United States)
Melodi Rodrigue, Univ. of Nevada (United States)
K. P. Cheng, California State Univ. Fullerton (United States)
R. Clark


Published in SPIE Proceedings Vol. 4087:
Applications of Photonic Technology 4

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