On-orbit adjustment concepts for the Generation-X Observatory

Daniel A. Schwartz; Roger Brissenden; Mark Freeman; Terrance Gaetz; Paul Gorenstein; Diab Jerius; Michael Juda; Paul Reid; Scott Wolk; Timo Saha; William Zhang; Stephen O'Dell; Susan Trolier-McKinstry; Derek Wilke

doi:10.1117/12.862353

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29 September 2010 On-orbit adjustment concepts for the Generation-X Observatory

Daniel A. Schwartz, Roger Brissenden, Mark Freeman, Terrance Gaetz, Paul Gorenstein, Diab Jerius, Michael Juda, Paul Reid, Scott Wolk, Timo Saha, William Zhang, Stephen O'Dell, Susan Trolier-McKinstry, Derek Wilke

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Proceedings Volume 7803, Adaptive X-Ray Optics; 78030J (2010) https://doi.org/10.1117/12.862353
Event: SPIE Optical Engineering + Applications, 2010, San Diego, California, United States

Abstract

Generation-X is required to be an X-ray observatory with 50 m2 effective collecting area and 0.1 arcsec half-power diameter (HPD) angular resolution at 1 keV. It is conceived that a launch vehicle such as that studied for the Ares V will carry a monolithic 16-m-diameter mirror to the earth-sun L2 point. Even with such a vehicle, the reflectors comprising the ≈ 250 nested shells must be extremely light-weight. Therefore their figure and alignment cannot be achieved on the ground, and likely could not be maintained through the launch environment. We will present a conceptual solution to those constraints: adjustable X-ray optics, as a case of "adaptive" optics where the stability once in orbit should require adjustments no more frequently than yearly. The figure would be adjusted via thin-film actuators deposited directly to the back (non-reflecting) side of each element. This bi-morph configuration would impart in-plane strains via the piezoelectric or electrostrictive effect. Requirements of the adjustment are to the order of a few nanometer precision. Each shell, and each module, must also be aligned, to tolerances of about 0.1 micrometer. We conceive that on-orbit data would be acquired by a built-in Hartmann system for the alignment adjustments and low-order figure, and by ring profile measurements of a very bright celestial X-ray source to correct figure errors up to the mid-frequency range of several hundredths cycles mm⁻¹.

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Daniel A. Schwartz, Roger Brissenden, Mark Freeman, Terrance Gaetz, Paul Gorenstein, Diab Jerius, Michael Juda, Paul Reid, Scott Wolk, Timo Saha, William Zhang, Stephen O'Dell, Susan Trolier-McKinstry, and Derek Wilke "On-orbit adjustment concepts for the Generation-X Observatory", Proc. SPIE 7803, Adaptive X-Ray Optics, 78030J (29 September 2010); https://doi.org/10.1117/12.862353

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