Acknowledgments

Status of the Tropospheric Wind Lidar Technology Experiment (TWiLITE) IIP Project Bruce Gentry,M. McGill, G. Schwemmer,, M. Hardesty, A. Brewer, T. Wilkerson, R. Atlas, M. Sirota, S. Lindemann, F. Hovis I&T Engineering team: Stan Scott, Roman Machan, Ryan Cargo, Dan Reed, Bill Hart, John Yorks, Dennis Hvlaka June, 2009

Acknowledgments • NASA SMD ESD ESTO (G. Komar) • NASA SMD ESD (R. Kakar) • NASA GSFC IRAD

Tropospheric Wind Lidar Technology Experiment (TWiLiTE) Instrument Incubator Program • The TWiLiTE instrument is a compact, rugged direct detection scanning Doppler lidar designed to measure wind profiles in clear air from 18 km to the surface. • TWiLiTE operates autonomously on NASA research aircraft (ER-2, DC-8, WB-57). • Initial engineering flight tests on the NASA ER-2 in February, 2009 demonstrated autonomous operation of all major systems. • TWiLiTE will mount in the DC-8 cargo bay using either the fore or aft nadir port. TWiLiTE system configured for ER-2 QBay TWiLiTE ER-2 IntegrationFebruary, 2009

Direct Detection Doppler Lidar Development Roadmap TWiLiTE Airborne Doppler Lidar 20 15 10 5 0 ER2 WB57 DC8 Altitude (km) TWiLiTE configured for ER2 Q-Bay (ESTO IIP04) TWiLiTE configured for WB57 3’ Pallet (ESTO IIP04) GLOW mobile lidar (SMD,NMP,IPO, ARO, ROSES07-WLS) TWiLiTE configured for DC8 Nadir Port 7 (ROSES07-AITT)

Airborne Lidar Wind Measurement Lidar ranging permits determination of wind speed as a function of altitude. Multiple look angles permit determination of vector wind.

TWiLiTE Direct Detection Wind Lidar Key Technologies

TWiLiTE Instrument Parameters Wavelength 354.7 nm Telescope/Scanner Area 0.08 m2 Laser Linewidth (FWHH) 150 MHz Laser Energy/Pulse (8 W) 40 mJ @ 200 pps Etalon FSR 16.65 GHz Etalon FWHH 2.84 GHz Edge Channel Separation 6.64 GHz Locking Channel Separation 4.74 GHz Interference filter BW (FWHH) 120 pm PMT Quantum Efficiency 25%

TWiLiTE Assembly and testing July – November, 2008 Optical bench, telescope and laser alignment Structure and lidar modules mounted to ER-2 frame Dust covers, heaters, wiring and plumbing added Insulation (1 to 3 inch thick) added

TWiLiTE Assembly and testing November, 2008 - January, 2009 Laser electronics, Data electronics and power distribution TWiLiTE atmospheric testing using turning mirror & roof hatch (vertical only) TWiLiTE assembly on ground support cart Looking up at 45 degrees into blaze of HOE

ER-2 Engineering FlightsFeb 17-27, 2009

Feb. 25 2009 Ground Data • Signal strength between 20-40 Mcounts/Sec in boundary layer • Very clean atmosphere – no significant clouds or aerosol

Feb. 19, 2009 Flight • Just over 7 minutes of lidar data (weak signals due to laser Temp ) • Raw data for Edge 1-High Energy Channel shows promising functionality: • Single shot; 30 m range resolution • Skies were primarily clear, but TWiLiTE did detect a contrail • Signal from the surface was also detected at approx 30 km in range

Feb. 19, 2009 Flight – Temps (1 of 2) • Pumps carrying coolant fail 20 minutes into the flight causing the laser to overheat (black and blue: top plot) • Other components are also affected such as the Heater Block (red: top plot) Science data Acq2 Etalon sweep 1 Etalon sweep 2

Etalon Calibration Sweeps

Summary and Future Plans • Integrated TWiLiTE into the ER-2 and verified all mechanical, electrical, thermal and control interfaces on the ground and in the air. • 2 hour test flight with pump not operating demonstrated key - functions: • Auto alignment system (ground returns form 30 km) • Etalon calibration and alignment sequence completed • Photon counting data acquisition • Laser seeding, thermal interlocks and restart • Observed failures were COTS parts (pump, CPU) not lidar components. We are repairing, testing and will deploy for additional flights this summer. • Reconfiguring TWiLiTE for integration on the DC-8 (ROSES07-AITT). Proposal submitted for summer 2010 hurricane experiment (GRIP)

Backups

Backscattered Spectrum DOP Aerosol (l-2) Molecular (l-4) Frequency Doppler Lidar Measurement Concept • DOPPLER RECEIVER - Multiple flavors dependent on scattering target - • Aerosol return gives high accuracy and high spatial and temporal resolution when aerosols present • Molecular return gives lower accuracy and resolution but signal is always there

ER-2 Flight Test Summary • 2/9 - Ship from GSFC • 2/17 – TWiLiTE arrives DFRC • 2/18 – Integration into ER2 • 2/19 – First 2 hour test flight. Coolant pumps fail 20 minutes into flight. Instrument performs autonomous turn on and calibration functions normally until laser T interlock turns off laser. Demonstrates key engineering functions • 2/20 to 2/22 – Replace pump with heavier duty industrial pump. • 2/23 - Warning light prior to take off scrubs flight • 2/24 – Ground crew not available. No flights • 2/25 to 2/26 – Surface winds exceed safe limits for takeoff. Ground tests of TWiLiTE with ER-2 pushed out from hangar • 2/26 – 3 hours of ground testing in hangar to verify software operations. At end of this period the instrument CPU began to reboot repeatedly. • 2/27 - Trouble shoot CPU without success. Determine repair or replacement in field is not practical. Pack instrument for return to GSFC

Feb. 19, 2009 Flight - Temps (2 of 2) • Despite issues with the pumps, the etalon & receiver temperatures remained relatively stable

Future Plans • Thermal system will be modified and tested • Data System Electronics Box will be tested and faulty CPU board replaced • Return to DFRC for additional flight tests on ER-2 planned in summer, 2009

Acknowledgments