1 / 14

NAST-I Development History

NAST-I Development History. Developed by MIT Lincoln Laboratory in 18 months for NPOESS using a COTS BOMEM (now ABB) interferometer, detectors, and optics Flown aboard NASA's high-altitude ER-2, Northrop Grumman Proteus aircraft, and NASA’s WB-57

ahava
Télécharger la présentation

NAST-I Development History

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NAST-I Development History • Developed by MIT Lincoln Laboratory in 18 months for NPOESS using a COTS BOMEM (now ABB) interferometer, detectors, and optics • Flown aboard NASA's high-altitude ER-2, Northrop Grumman Proteus aircraft, and NASA’s WB-57 • Produces high spatial and spectral resolution data suitable for synthesizing data products of candidate NPOESS sounders • NAST-I has achieved excellent performance logging over 850 operational hours to date

  2. NAST-I Overview • Instrument Characteristics • infrared Michelson interferometer • (9000 spectral channels) • 3.5 – 16 microns @ 0.25 cm-1 • Aircraft Accommodation • ER-2 Super pod & Proteus Underbelly pod • Radiative Measurement Capability • calibrated radiances with • 0.5 K absolute accuracy, 0.1 K precision Spatial Resolution 130m/km flight alt. (2.6 km from 20km) Swath Width 2 km /km flight alt. (40 km from 20 km) Temperature (K) Water Vapor Mixing Ratio( Uncorrected) Relative humidity (%)

  3. NAST Flight History ER-2 MAS • 1998-2004: 17 Missions • 152 Mission sorties • 850 Flight hours NAST-I S-HIS NAST-M Proteus S-HIS NAST-M NAST-I

  4. NAST-I Major Characteristics Detector Characteristics LW band 7.8 – 16.1mm PC HgCdTe cooled to 77K MW band 4.8 – 7.8mm PC HgCdTe cooled to 77K SW band 3.7 – 4.8mm PV InSb cooled to 77K detector size 1 mm entrance pupil diameter 0.28in scan angle +/- 48.4maximum IFOV 7.45 collimated beam diam. in interferometer 1.5in beamsplitter/compensator 1.9in clear aperture KBr alignment technique dynamic based on HeNe laser OPD +/- 2.0cm (high resolution mode) OPD velocity 5.2cm/sec, RMS variation under 1% sweep time 0.77sec turnaround time 0.044sec Input Optics Micheleson Interferometer

  5. NAST-I Schematic

  6. Background Radiance in NAST-I • NAST-I operates at room temperature (ground and flight) • Cold field stop and baffles within detector package significantly reduce background radiation from surrounding structures • Some flux is modulated by the interferometer and detected NAST Detector Assembly Optical Bench

  7. NAST-I System Diagram InputOptics AftOptics 1.2Gbyte disk cm sec temporal f (sec-1) spatial n (cm-1) IR Light Detectors and Preamplifiers Micheleson Interferometer optical signal (photons) flight computer electrical signal (V) Anti-aliasing filter A/D DSP Card PCI bus SCSI bus 133MHz Triton Pentium Single Board Computer

  8. Scanning Interferometer Sounder 4 – 16 m NAST Layout In ER-2 SuperPod ER-2 at Patrick AFB MIT/RLE Microwave Sounder Electronics, Control & Navigation NASA ER-2 Processing & Recording NADIR 2.6km IFOV 20km Altitude +/- 23km Ground Swath

  9. Proteus Configuration NAST-I 3.5 – 16micron @ 0.25 cm-1 • NAST-M • (54, 118 GHz)

  10. WB-57 Pallet Configuration NAST-I Rack designed by SED/MSB and fabricated by SED fab WB-57 Pallet

  11. Compare Model and Measurements: Flight 98-117 Data

  12. Background Brightness Temperature Theoretical Hot, Amb cal target flux Hot, Amb cal target measurement Calibrated Responsivity Background Flux Brightness Temp • Background estimate is obtained from: • Background is 180o out-of-phase with scene radiation • Spectral signature indicates it is reflected off of Black Anodized Al • Mounts, and most structures on the bench are Black Anodized Al • Bkgd differs from ground to flight • Including background in alignment NEdN calculation is essential for obtaining accurate results Simulate Background using Black Anodize Reflectivity Tsimulated =>[Ranodize * BB(285 K)]+BB(240 K) Estimated Ranodize Measured Ranodize ** Ranodize measurements were performed on Black Anodize Al similar to that found on NAST-I

  13. Modification History MW detector LW detector • Beamsplitter replacement • Improved shock mounts/isolation • PID thermal control of canister • Circuit added to DA servo control to insert static offset in both sweep directions (UW) • Gain tuning of DA servo gains • Component replacement in DA servo and metrology laser electronics • LW detector, cooler, and optics SW detector

  14. NAST-I Lessons Learned • Worked well • Integrated Dewar Cooler Assembly (IDCA) • Stirling cycle cooler • Reflective optical design • Coregistration • Bomem interferometer • MIT LL Porch swing • Simple design: reliability • What could be better • LW detector performance • Data collection • Data quicklook analysis • Vibration isolation • BS/CS wedge • More metrology signals • Improved GPS

More Related