THAI-SPICE IS THE TESTBED FOR HIGH-ACUITY IMAGING - STABLE PHOTOMETRY AND IMAGE-MOTION COMPENSATION EXPERIMENT -- IT IS A LEAD PROPOSAL ACCOMPANIED BY A CO-INSTITUTIONAL PROPOSAL FROM MIT LL. THE OVER ARCHING GOAL OF THAI-SPICE IS TO ADVANCE BALLOONBORNE TELESCOPES TO THE POINT WHERE THEY CAN SURPASS HST IN TERMS OF SPATIAL RESOLUTION IN VISIBLE WAVELENGTHS AND SURPASS THE KEPLER MISSION IN TERMS OF OBSERVING EXOPLANET TRANSITS. BALLOON-BORNE TELESCOPES ARE BECOMING AN IMPORTANT PART OF NASA'S OBSERVING PROGRAMS -- EACH 100-DAY SUPER-PRESSURE BALLOON FLIGHT WILL PROVIDE 1000 HOURS OF DARK TIME OBSERVING EQUIVALENT TO ABOUT 1/3 OF THE TOTAL ON-TARGET TIME ALLOCATED IN AN HST CYCLE ACROSS ITS ENTIRE PORTFOLIO OF SCIENCE PROGRAMS. HOWEVER BALLOON-BORNE TELESCOPES FACE UNIQUE CHALLENGES FROM THE STRATOSPHERIC THERMAL ENVIRONMENT AND THE POINTING STABILITY OF A SUSPENDED PLATFORM. THIS PROPOSAL WILL STUDY AND TEST THREE AREAS OF DEVELOPMENT THAT WILL ENABLE HIGH-ACUITY IMAGE QUALITY AND STABLE PHOTOMETRY FROM BALLOON-BORNE TELESCOPES. - PASSIVE THERMAL CONTROL AND STABILIZATION OF BALLOON-BORNE OTAS (OPTICAL TUBE ASSEMBLIES). RECENT MODELING SUGGESTS THAT AN APPROPRIATE ARRANGEMENT OF SUNSHIELDS EARTH-SHIELDS AND TELESCOPE INSULATION CAN REDUCE DIURNAL TEMPERATURE EXCURSIONS FROM MORE THAN 40 C TO LESS THAN 2 C. FURTHERMORE MODELING ALSO SUGGESTS THAT THE STEADY-STATE TEMPERATURE OF AN OTA CAN BE REDUCED TO TEMPERATURES NEAR 180 K AN ADVANTAGE FOR INFRARED OBSERVING PROGRAMS. HOWEVER MOST MODELING PACKAGES (E.G. THERMAL DESKTOP) DO NOT ACCURATELY ACCOUNT FOR CONVECTION IN THE 3 TORR OR 8 TORR ENVIRONMENT OF ZERO-PRESSURE OR SUPER-PRESSURE BALLOONS. IN FACT IT IS HARD TO TELL WHETHER RADIATION OR CONVECTION IS A MORE SIGNIFICANT COOLING MECHANISM AT SUPER-PRESSURE BALLOON ALTITUDES. WE PROPOSE TO VERIFY OR UPDATE THERMAL DESKTOP RESULTS WITH A SERIES OF EXPERIMENTS USING AN INSTRUMENTED OTA AND SUN- AND EARTH-SHIELDS. THE PAYOFF FROM THIS EXPERIMENT WILL BE BALLOON-BORNE TELESCOPES THAT EXHIBIT EXTREMELY STABLE TEMPERATURES THROUGH DAY-NIGHT CYCLES AND IN TURN AVOID OPTICAL MISALIGNMENT DUE TO TEMPERATURE EXCURSIONS. - ORTHOGONAL TRANSFER CCDS AS SOLID-STATE MOTION COMPENSATION DEVICES. IN ORDER TO STAY WITHIN A WAVEFRONT ERROR BUDGET THAT IS COMPARABLE TO WFIRST OR HST A BALLOON-BORNE IMAGING SYSTEM CANNOT AFFORD A SINGLE MEDIOCRE OPTICAL ELEMENT. FINE STEERING MIRRORS ARE ESPECIALLY PROBLEMATIC SINCE THEY ARE OFTEN THIN LIGHTWEIGHT AND MOUNTED TO A FAST-MOVING MECHANISM. WE WILL TEST THE PERFORMANCE OF OTCCDS ON ACTUAL BALLOON PLATFORMS TO ASSESS HOW THEY CAN COMPENSATE FOR FOCAL PLANE MOTION IN FLIGHT. IN ADDITION WE WILL MEASURE THE PHOTOMETRIC STABILITY AFFORDED BY OTCCDS AND WHETHER PURPOSELY MOVING A POINT SOURCE IN A PATTERN CAN IMPROVE PHOTOMETRY BY PSF-SHAPING AND SPREADING THE SIGNAL OVER MANY ARRAY ELEMENTS. - IN-FLIGHT WAVEFRONT ERROR MEASUREMENTS. DURING A 100-DAY MISSION IT WILL BE USEFUL TO MONITOR THE FOCUS AND OPTICAL ALIGNMENT OF THE TELESCOPE AND THE ATTACHED INSTRUMENTS. A SHACK-HARTMANN ARRAY LOCATED AT AN EXIT PUPIL WILL PROVIDE A DETAILED BREAKDOWN OF THE OPTICAL SYSTEM: COMPACT COMMERCIAL UNITS OFTEN PROVIDE OVER 15 ZERNIKE POLYNOMIALS. WE WANT TO TEST ANOTHER METHOD THE CURVATURE WAVEFRONT SENSING METHOD (AKA THE RODDIER METHOD). THE CWS METHOD ONLY REQUIRES IMAGES ON EITHER SIDE OF FOCUS. IT DOES NOT REQUIRE EXTRA HARDWARE NOR ACCESS TO AN EXIT PUPIL. WE WANT TO DEMONSTRATE THE CWS METHOD IN FLIGHT AND COMPARE ITS RESULTS TO A CONVENTIONAL SHACK-HARTMANN ARRAY. ALL OF THESE PROJECTS LEVERAGE PRIOR WORK SOME SUPPORTED BY PREVIOUS APRA PROJECTS SOME PART OF NASA'S ONGOING GHAPS PROJECT (GONDOLA FOR HIGH ALTITUDE PLANETARY SCIENCE). WE PROPOSE TWO DOMESTIC FLIGHTS WITH A 24-IN INSTRUMENTED TELESCOPE AND A GONDOLA CAPABLE OF COARSE POINTING. THIS PROJECT WILL INVOLVE STUDENTS FROM THE UNIVERSITY OF VIRGINIA AND THE UNIVERSITY OF COLORADO.