Electronic Resource
Characterization and calibration of the James Webb space telescope mirror actuators fine stage motion
| العنوان: | Characterization and calibration of the James Webb space telescope mirror actuators fine stage motion |
|---|---|
| المؤلفون: | Lystrup, Makenzie, MacEwen, Howard A., Fazio, Giovanni G., Batalha, Natalie, Siegler, Nicholas, Tong, Edward C., Chonis, Taylor S., Gallagher, Ben B., Knight, J. Scott, Acton, D. Scott, Smith, Koby Z., Wolf, Erin, Coppock, Eric, Tersigni, James, Comeau, Thomas |
| بيانات النشر: | Society of Photo-optical Instrumentation Engineers (SPIE) 2018-07-12 |
| نوع الوثيقة: | Electronic Resource |
| مستخلص: | The James Webb Space Telescope’s (Webb’s) deployable primary and secondary mirrors are actively controlled to achieve and maintain precise optical alignment on-orbit. Each of the 18 primary mirror segment assemblies (PMSAs) and the secondary mirror assembly (SMA) are controlled in six degrees of freedom by using six linear actuators in a hexapod arrangement. In addition, each PMSA contains a seventh actuator that adjusts radius of curvature (RoC). The actuators are of a novel stepper motor-based cryogenic two-stage design that is capable of sub-10 nm motion accuracy over a 20 mm range. The nm-level motion of the 132 actuators were carefully tested and characterized before integration into the mirror assemblies. Using these test results as an initial condition, knowledge of each actuator’s length (and therefore mirror position) has relied on software bookkeeping and configuration control to keep an accurate motor step count from which actuator position can be calculated. These operations have been carefully performed through years of Webb test operations using both ground support actuator control software as well as the flight Mirror Control Software (MCS). While the actuator’s coarse stage length is cross-checked using a linear variable differential transformer (LVDT), no on-board cross-check exists for the nm-level length changes of the actuators’ fine stage. To ensure that the software bookkeeping of motor step count is still accurate after years of testing and to test that the actuator position knowledge was properly handed off from the ground software to the flight MCS, a series of optical tests were devised and performed through the Center of Curvature (CoC) ambient optical test campaigns at the Goddard Space Flight Center (GSFC) and during the thermal-vacuum tests of the entire optical payload that were conducted in Chamber A at Johnson Space Center (JSC). In each test, the actuator Fine Step Count (FSC) value is compared to an external measurement provided by |
| مصطلحات الفهرس: | Book Section, PeerReviewed |
| URL: | CaltechAUTHORS:20181207-145745028 10.1117/12.2311815 |
| الاتاحة: | Open access content. Open access content other |
| ملاحظة: | application/pdf Characterization and calibration of the James Webb space telescope mirror actuators fine stage motion English |
| Other Numbers: | CIT oai:authors.library.caltech.edu:91580 https://authors.library.caltech.edu/91580/1/106983S.pdf Chonis, Taylor S. and Gallagher, Ben B. and Knight, J. Scott and Acton, D. Scott and Smith, Koby Z. and Wolf, Erin and Coppock, Eric and Tersigni, James and Comeau, Thomas (2018) Characterization and calibration of the James Webb space telescope mirror actuators fine stage motion. In: Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave. Proceedings of SPIE. No.10698. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 106983S. ISBN 9781510619494. https://resolver.caltech.edu/CaltechAUTHORS:20181207-145745028 <https://resolver.caltech.edu/CaltechAUTHORS:20181207-145745028> 1080552523 |
| المصدر المساهم: | CALIFORNIA INST OF TECH From OAIster®, provided by the OCLC Cooperative. |
| رقم الانضمام: | edsoai.on1080552523 |
| قاعدة البيانات: | OAIster |
| الوصف غير متاح. |