1. TEMPO Instrument Update Dennis Nicks, TEMPO PM May 21-22, 2014 (303) 939-4467 dnicks@ball.com

2.  Instrument design is maturing with PDR in July 2014 Performance estimates have been updated based on design maturity Updated operating parameters to optimize instrument performance  At NASA KDP-B Instrument cost risk is perceived to be too high Ball, LaRC, and SAO worked closely to evaluate current instrument performance and science performance SAO and LaRC are able to accept the current instrument performance with little impact to science SNR, Spectral Stability, dark current Issues remain with stray light – need to work with LaRC/SAO on definitions and resolution  Mission Level INR requirements have been allocated to subsystems Instrument pointing performance has been rolled up into Mission Level INR – everything closes TEMPO Instrument Status 5/21/20142

3. TEMPO Design Maturation Since Last Science Meeting 3 Design Presented at 7/2013 Science Team Meeting Pre-PDR Design as of 5/2014 5/21/2014

4. Detector Update 45/21/2014

5. ParameterSRR ValuePDR Baseline Notes Frame Integration Time 95.83 ms118 ms A longer frame integration time marginally improves SNR performance and gives flexibility for seasonable variations in lighting conditions. Image Frame Rate10 Hz8.19 Hz Includes frame integration time and frame transfer time of 4.17 ms. 10 Hz is the maximum frame rate. Image Frame Time2.70 s2.69 s Includes integration time, frame transfer time, and coadds. Number of Coadds2722 Number of coadds must adjust with integration time to meet the coverage time requirement. Scan Mirror Step Size 115 urad114 µrad The measure of E/W overlap and the requirement has changed since SRR. New requirement will be 6µrad based on INRWG analysis presented by Benton Ellis on 4/30/2014. Number of Scan Mirror Steps 12671278 Number of scan mirror steps increased slightly due to the slightly smaller scan mirror step size. Coverage Time59.14 min59.39 min A more careful accounting of coverage time is now being done, courtesy of Roger Drake. Coverage time includes book keeping for flight software timing margin from the end of a scan to the beginning of a scan (10 seconds), scan mirror move time at the end and beginning of a scan (4.75 s), scan mirror step/settle (50 ms), ICE commanding step/settle (50 ms). TEMPO Parameter Evolution 55/21/2014

6.  Previous SNR model assumed aggressive mirror reflectivity and grating efficiencies Dielectric coatings for mirrors allow for high performance over a broad spectral range However they often increase spectral features and polarization  TEMPO design has more optical elements Polarization wave plate and corrector lens in front of FPA  New TEMPO SNR estimates assume “as manufactured” grating efficiency of 55% (was 60%) and mirror reflectivity curves – based on GeoTASO Lower risk posture is highly desirable given the Earth Venture cost cap Allows adequate design space between SNR requirement (minimum optical throughput) and saturation requirement (maximum optical throughput) Worked with SAO and LaRC to assess impacts to science Impact to primary chemical species is negligible Secondary chemical species that have been removed can be added back when cost risk is less of a concern SNR 65/21/2014

7. Original TEMPO Requirements: Total System Optical Throughput  The margined curves (red) indicate that no system throughput will meet the SNR requirement with 20% margin and the saturation requirement with 10% margin  Having a gap between curves of less than 10% translates to coating tolerances that are likely not achievable 5/21/2014

8.  Dark Current requirement at 290-300 nm affects the SNR requirement (need for higher optical throughput) Dark current is within requirements for the rest of the spectral range  After discussions – the Dark Current requirement has been dropped for wavelengths below 300 nm. Dark Current 85/21/2014

9. New SNR Requirements vs Performance 9  New SNR requirements are result of BATC/SAO/LaRC negotiations Utilizes the new operating parameters Allows for manufacturability of optical elements and coatings Uses new retrieval assumptions from SAO / Xiong Reduces instrument project cost risk 5/21/2014

10. ISD 6.7.7Spectral Stability The instrument shall have a spectral stability better than 0.02nm (1-sigma) for all data collected that mets the requirements in Section 6.6.1 and Section 6.7.1 over any 24-hour time period New: ISD 6.6.7Spectral Stability of Radiances versus Irradiances The Instrument shall have a spectral stability of radiances compared to irradiances of better than 0.2 nm (1-sigma) for all data collected that meet the requirements in Section 6.6.1 and Section 6.7.1 over any 24-hour time (midnight-midnight) period. ISD 6.6.8Spectral Stability of Radiances The Instrument shall have a spectral stability for radiances of better than 0.1 nm (1-sigma) for all data collected that meet the requirements in Section 6.6.1 and Section 6.7.1 over any 24- hour time (midnight-midnight) period. ISD 6.6.9Spectral Stability of Irradiances The Instrument shall have a spectral stability for irradiances of better than 0.1 nm (1-sigma) for all data collected that meets the requirements in Section 6.6.1 and Section 6.7.1 over any 24- hour time (midnight-midnight) period. Spectral Stability Requirement 105/21/2014

11.  The single Spectral Stability requirement over a 24 hour period was extremely challenging The design already had a low-CTE structure, athermal optics and an active thermal design Would require extremely precise thermal control over all solar geometries  Worked with science team to rephrase the requirement to allow for easier compliance while still meeting science requirements Specify spectral stability for radiance measurements (Earth View), irradiance measurements (solar cal) and allowable shifts between radiance and irradiance  Change allows for smart instrument design / operational trades with no impact to science Spectral Stability 115/21/2014

12. ISD 6.6.7 Stray Light The Instrument shall have a stray light response less than 2% of the Instrument response over the spectral range of 290 to 740 nm for the hemispherical angle of incidence for the nominal radiances in Table 1. The definition of stray light is the ratio of the sum of contributions from sources (e.g., scatter, ghosts from lenses, windows, and focal plane reflections) originating from outside the point source function being evaluated to the signal inside the point source image area of interest. For the purposes here, inside the point source image area is defined as a box on the focal plane 15 x 15 pixels centered on the point source. Stray Light Requirement 125/21/2014

13.  Design / Trade Studies Includes baffling design iteration Scatter from surface roughness/particulate contamination Waveplate angle of rotation  Ghosting contributors  New analysis indicates that the largest stray light contributor for TEMPO is the grating Used BRDF measurements of “as manufactured” grating BRDS model fitting Grating efficiency / orders  Requirement is worded as Point Spread Function (PSF) stray light Less than 2% of the instrument response over the spectral range of 290-740 nm Stray Light Status 135/21/2014

14. System Stray Light Compliance System Level Requirement Optical Surface Scatter/Ghosting Grating Scatter/Artifacts Mechanical Surface Scatter < 2% < 0.75% < 1.0% < 0.25% Goal Allocations Wavelength (nm) Grating Model A Optical Ghosting SL (%) B Optical Surf. Scatter SL (%) C Grating SL (%) D Mechanical Surf. SL* (%) Model Contingency** (%)Total (%) Total w/Contingency (%) 303 ZW_base 0.050.430.750.25 1.011.482.49 ZW_1 0.050.431.130.25 1.011.872.87 400 ZW_base 0.250.400.950.25 1.261.853.10 ZW_1 0.250.401.400.25 1.262.303.56 497 ZW_base 0.070.301.000.25 1.241.622.86 ZW_1 0.070.301.390.25 1.242.013.25 Preliminary Results from F. Grochocki * Stray light contributions from mechanical surfaces have not been analyzed – 0.25% allocation is assumed ** Model contingency = 5/21/2014

15.  Current estimates based on PSF show some areas of non- compliance  Further discussions with Science Team at LaRC and SAO indicated that PSF interpretation may not be correct 15 x 15 pixel box confuses the interpretation of the requirement and may be deleted May be more correctly interpreted in a broadband sense, where measured stray light needs to be <2% of signal electrons Most challenging at the 290 – 300 nm range where there is low signal  Ball / SAO / LaRC are working stray light requirement interpretation Discussions are on-going regarding the wording of the stray light requirement Stray Light Summary 5/21/201415

16. KTP Summary: Science Performance (1 of 3) 5/21/201416

17. KTP Summary: Science Performance (2 of 3) * C.F. = Chance Farm at Geodetic 36.5° N, 100° W 5/21/2014

18. KTP Summary: Science Performance (3 of 3) SNR Wavelength SNR Requirement SNR Performance This Month Notes 29019.624 Significant updates based 30046.156 on realistic optical and 305161.9196 QE information. 310377456 32012201473 33020032419 34020132431 35014142299 4208361734 4306751401 4507331423 450 nm is a new reqmt. 49011761411 54011091340 6009871193 6508981085 690820975 5/21/2014

19.  Instrument design is maturing quickly Instrument is designed for high structural / thermal stability Instrument performance is based on “as-manufactured” optical components based on GeoTASO experience  Some changes to TEMPO performance requirements were required to reduce perceived cost risk Worked closely with Science Team to relax requirements without severely impacting science Science analysis / algorithm development descopes can be added back if cost risk allows Low risk posture highly desirable at NASA HQ Summary 5/21/201419