FTS Test Definition Summary Kaley Walker Test Readiness Review January 29, 2003

What Needs to be Done Performance testing of: –Passive cooler / detectors –Suntracker / co-registration –Imagers –Spectrometer (ILS, FOV etc.)

Passive Cooler Evaluate performance of passive cooler using He cooled target Monitor detector and target temperatures –While cooling from room temperature –During instrument temperature transitions Priority 1

Detector Temperature Measure while cooling detector – every 5 K from 110 → 70? K High resolution spectra + N 2 O gas cell –Examine ILS vs. T and estimate NESR –Retrieve temperature and pressure Low resolution spectra –Bandpass characteristics Priority 1

Detector Non-linearity Measure while cooling detector – every 5 K from 110 → 70? K Low resolution interferograms –At 1750, 2250, 2750 K ( K from previous) –Ratio of centre burst to first side lobe to calculate –5800 K point measured on orbit Priority 1

Operational Cycling Measure at 90 K and lowest achieved T Simulate normal operational power dissipation –Cycle between SCIENCE and SLEEP mode as for nominal occultation –Monitor detector temperature for any changes in cooling rate Priority 3

Detector Monitoring InSb Instability (Priority 1) –Monitor channel for recurrence of problem Contamination Monitoring (Priority 1) –Measure low resolution spectra every 12 hours using 2273 K HBB –Need criteria for when decontamination should be initiated

Suntracker Sunscan – exercise mode using typical scan for MAESTRO calibration (Priority 1) Stability – measure in closed loop with sunrise simulator (~50 s occultation) (Priority 2) Pointing – characterize pointing over ±1.5 ° range using “leapfrog” technique (Priority 2) + 80 mrad A. Setup suntracker mirror to point here. B. Move collimator mirror to move image here

Co-registration MAESTRO to VIS (Priority 2) –On bench with 532 nm laser source and in TVac with Xe lamp and pinhole FTS to NIR (Priority 2) –Combined QI / HBB source and pinhole NIR to VIS Registration (Priority 3) –relative orientation and pixel offset between arrays

Imager Characterization Flat Field Bench –Solar simulator to provides uniform illumination (Priority 2) Flat Field TVac –Illuminate stepwise using QI source (Priority 2) Non-linearity TVac –Stepwise illumination and vary attenuation (Priority 2)

Imager Charaterization Gain – characterize imager settings (Priority 2) Dark Current – measure versus instrument temperature; perform prior to each test with imagers (Priority 2) Cropping – test modes with sunrise simulator and attenuated source (Priority 3)

Gas Cell Measurements Combined – Measure NO 2 and O 3 with both FTS and MAESTRO (Priority 2) –compare retrieved temperature and pressure values Additional – N 2 O measurements with FTS at instrument temperature plateaux (Priority 2) –Examine ILS vs. T and estimate NESR –Retrieve temperature and pressure

Gas Cell Measurements Occultation – Use suntracker to follow simulated occultation and measure FTS (and MAESTRO) spectra (Priority 3) –Have to step through occultation to allow for time for sufficient coadds –Suntracker pointing in closed-loop at fixed source –Somewhat unwieldy test that cannot provide “test as we fly” conditions

FTS Tests IR FOV – Move shutter stepwise across FOV and measure ZPD (Priority 2/3) Non-uniform FOV Illumination – Use split attenuator to observe ILS effects (Priority 3) Modulation Efficiency – To be done by Bomem (Priority 2)

Limit in Testing HBB cavity lifetime ~30-40 minutes at 3273 K and we only have 4 cavities Almost all tests done at max. temperature –Priority 1 ~ 57 minutes –Priority 2 ~ 65 minutes –Priority 3 ~ 268 minutes Majority of # 3 is Occultation – 223 minutes –without it we should have enough HBB lifetime to complete testing program

Issues Detector Decontamination –Need criteria for when this should be initiated Occultation test –Significant drain on HBB lifetime –Recommend deleting from test schedule