ADJUSTABLE X-RAY OPTICS ARE A POTENTIAL TECHNOLOGY TO ACHIEVE THE DIFFICULT REQUIREMENTS (IMAGING RESOLUTION COLLECTING AREA TELESCOPE SIZE AND MASS) OF THE LYNX MISSION CONCEPT - A POTENTIAL SUCCESSOR TO THE CHANDRA X-RAY OBSERVATORY. WHILE ADJUSTABLE OPTICS BY THEMSELVES HAVE NUMEROUS TECHNICAL ADVANTAGES OVER MORE CONVENTIONAL MIRROR TECHNOLOGIES ON-ORBIT FIGURE MONITORING OFFERS THE OPPORTUNITY TO UTILIZE THE FULL POTENTIAL OF ADJUSTABLE OPTICS BY ENABLING MIRROR FIGURE CORRECTION ON-ORBIT IN RESPONSE TO DISTURBANCES TO MIRROR FIGURE DUE TO THE CHANGING THERMAL ENVIRONMENT RESULTING FROM VARYING SPACECRAFT EXPOSURE TO THE SUN. THE ABILITY TO CORRECT ON-ORBIT FOR THERMALLY INDUCED CHANGES REPRESENTS A CAPABILITY THAT IS NON-EXISTENT WITH ANY OTHER MIRROR TECHNOLOGY AND COULD PROVE CRITICAL FOR THE FIRST HIGH ANGULAR RESOLUTION THIN MIRROR X-RAY TELESCOPE. DEVELOPMENT OF THIS CAPABILITY MAY: (1) EASE TELESCOPE THERMAL CONTROL SYSTEM REQUIREMENTS (2) EASE CONSTRAINTS ON TELESCOPE POINTING WITH RESPECT TO THE SUN AND (3) RELAX CONSTRAINTS ON MIRROR MOUNTING ATHERMALIZATION SIMPLIFYING DESIGN AND BUILDING LYNX. OUR APPROACH TO ACHIEVE ON-ORBIT FIGURE MONITORING AND CONTROL IS TO INCORPORATE SEMICONDUCTOR STRAIN GAUGES DIRECTLY IN THE FABRICATION OF THE ADJUSTABLE X-RAY OPTICS AND USE THE MEASURED CHANGE IN LOCAL STRAIN TO DETERMINE CHANGES IN MIRROR TEMPERATURE AND SHAPE FOR SUBSEQUENT [REMOTE] FIGURE CORRECTION. SEMICONDUCTOR STRAIN GAUGES ARE USED TO MEASURE STRAINS AS SMALL AS 10 PARTS PER BILLION CONSISTENT WITH 0.5 ARCSEC IMAGING FOR SOME BENDING SPATIAL WAVELENGTHS. IN THIS RESEARCH PROGRAM WE WILL DEVELOP THE CAPABILITY TO DIRECT DEPOSIT SEMICONDUCTOR STRAIN GAUGES ON PIEZOELECTRIC MIRROR CELLS INVESTIGATE THE LIMITING ACCURACY OF STRAIN MEASUREMENTS AND UNDERSTAND THE SEPARATE SENSITIVITY OF THE STRAIN GAUGES TO TEMPERATURE CHANGES. WE WILL DEVELOP THE TECHNOLOGY TO DEPOSIT STRAIN GAUGES INSENSITIVE TO MIRROR IN-PLANE STRAIN AND THEREBY SENSITIVE ONLY TO MIRROR TEMPERATURE. WE WILL DEVELOP ANALYSIS ALGORITHMS AND INCORPORATE MEASURED MIRROR TEMPERATURE DATA TO CORRECT THE MEASURED BENDING STRAIN FOR THERMAL EFFECTS AND DEVELOP SUITABLE CONTROL ALGORITHMS TO USE THAT INFORMATION TO CORRECT MIRROR FIGURE. WE WILL ALSO INVESTIGATE THE SHORT AND LONG TERM STABILITY OF THE STRAIN GAUGES TO ASSESS FEASIBILITY FOR A 5 YEAR PLANNED MISSION PLUS TELESCOPE ASSEMBLY AND POTENTIAL CONTINUED OPERATION POST NOMINAL AND METHODS OF DETERMINING AND ACCOUNTING FOR ANY STRAIN GAUGE CALIBRATION DRIFT.
$1,007,295FY2020National Aeronautics and Space AdministrationNASA
Smithsonian Institution, Washington DC