CALIPSO On-Orbit - Lidar

Cloud - Aerosol Lidar and Infrared Pathfinder Satellite Observations

Lidar Data “Curtain”

Carl Weimer 3/21/07 Outline

z Why CALIPSO?

z Some Early Science Results

z Selected Engineering Results

Principal Investigator – David Winker – NASA LaRC Co-PIs – Patrick McCormick (Hampton University) and Jacque Pelon (IPSL)

NASA - Ball Payload

CNES – Alcatel Proteus Spacecraft

Summary: The CALIPSO Satellite has three instruments including the CALIOP Lidar. CALIOP is a two-wavelength (532 /1064 nm) polarization-sensitive Rayleigh-Mie lidar. Launched April 29, 2006 Scientific Need for CALIPSO

Scientists understanding of human impact on the Earth’s Radiation Budget - Global Warming

CALIPSO Will Help Address

How Aerosols Affect Clouds

From: IPCC 2001 CALIPSO offers unique contributions to help address important questions in climate change and air quality. New applications are being explored (e.g. Ocean) CALIPSO Lidar First Light (from NASA LaRC)

Travel

Cirrus Clouds Volcanic plume

Aura/OMI Column SO 2 CALIPSO Orbit Track 8 June 2006 7 June 2006

Soufriere (Montserrat – Caribbean) erupted on May 20. Its water droplet/sulfuric acid plume was tracked by OMI and seen crossing over Indonesia by CALIPSO on June 7. CALIPSO and CloudSat Data

Antarctica CALIPSO-Lidar

Polar Stratospheric Cloud

CloudSat - Radar CALIPSO Data – All Three Lidar Channels

Desert Cirrus Biomass dust smoke

Fire locations in southern Africa from MODIS, 6/10/06 Altitude, km Altitude, km Altitude, km

56.71 47.85 39.92 31.94 23.93 15.90 7.81 -0.23 -8.28 -16.31 -24.33 -32.32 -40.27 32.16 28.57 25.78 23.46 21.42 19.55 17.77 16.05 14.23 12.56 10.69 8.64 6.30

Ratios of Channels give estimate of particle size, particle shape, and differentiate water/ice clouds Antarctic Polar Stratospheric Clouds July 24, 2006

532 nm Total Attenuated Backscatter

532 nm Perpendicular Attenuated Courtesy: Dave Winker Backscatter Validation Intercomparisons: Aerosols

August 10, 2006 Coincidence

CALIPSO CALIPSO HSRL

532 nm Attenuated Backscatter (km-1 sr-1)

LaRC HSRL CALIPSO HSRL

1064 nm Attenuated Backscatter (km-1 sr-1) NASA LaRC High Spectral Resolution Lidar is being Coincidence flown on Aircraft to support validating CALIPSO Data Courtesy: Dave Winker What is different about Lidar from Space?

z Long distance from atmosphere – 400- 800 km Low Earth Orbit (LEO) – – Low Signal-to-Noise because of 1/R2 term in lidar equation – Looking down through atmosphere- strongest scatter from furthest distance – Ground/Ocean scatter sets far boundary condition – Satellite motion, typical LEO velocity 7000 m/s – limits averaging time z Space Environment – Radiation (Galactic, Solar, Van-Allen Belts) – Vacuum – Outgassing and Contamination concerns – Microgravity – Alignments different than on Earth – Atomic Oxygen – Erosion and reaction – Micrometeroids and space junk – Charging of Surfaces – Corona Discharge – Thermal environment – Controlled through careful design using radiators and heaters z Launch Environment – Alignments and structure must withstand vibration and shock – Limited Weight can be lifted – Typical 100 – 500 kg range for instrument z Limited power available – Typical 100 – 500 W available from solar arrays for instrument z Semi-Autonomous Operation over multiple years – Daily data downlink, weekly uplinks Lidar in Space Building for Reliability

• High Cost of Space Missions requires that a space lidar be designed and built to achieve maximum reliability affordable within cost and schedule constraints • Standard Aerospace Engineering practices followed, combined with unique lidar specific techniques • High Reliability Parts Program •Electronic Parts are all “screened” – tested for lifetime – this limits what parts can be used •All classes of parts must have passed radiation testing •Optical parts must be able to withstand radiation, Ultra-violet, laser fluence (if appropriate), vacuum, atomic Oxygen • Parts, Sub-assemblies, Assemblies must pass Qualification Test Program •Thermal-vacuum •Vibration •Acoustic •Shock •Electromagnetic Interference •Health/Performance tests in conjunction with each of the above Different Views of CALIPSO Payload

Wide Field Camera – Sun Shade BATC CT- X-Band Antenna 633 Star Tracker Assembly - French

X-Band Transmitter Payload Laser Electronics Unit Controller - Fibertek Imaging Infrared Receiver Power Supply Lidar Receiver Integrated Lidar Radiometer - Electronics Transmitter - Sodern Fibertek lasers Lidar Core – Transmitter and Receiver

Etalon Filter Adjustable Boresight APD Mechanism

PMTs - Laser LaRC Radiator

Optical Laser Bench Optics Modules

Telescope – 1 meter Beam Beryllium Expander Optics

ILT (Integrated ILR (Integrated Lidar Transmitter) Lidar Receiver) CALIPSO – Random Numbers

z Lidar Data “Curtain” – 70 meter diameter footprint – 330 meter steps – 30 meter (and up) vertical range bins – Extends from the ground to 40 km (130,000 ft - clean air) z Lasers – 4 Watt average power, 11 MWatt peak (20 nsec pulse), 20 Hz repetition – Each laser pulse contains 1018 photons – All the light is contained in very narrow wavelength bands • 0.035 nm at 532 nm (1 part per 15,000) • 0.100 nm at 1064 nm (1 part per 11,000) z Photomultiplier Detectors used at 532 nm are sensitive to single photons (but not photon counting) – Avalanche Photodiode used for 1064 nm – less sensitive but much more rugged (also 550 V vs 2 kV) z To date - on-orbit – 1.1 TByte of science data collected – 440 Million laser shots “fired” (1900 Mshots = full mission) Space Qualified Lasers

z Built by Fibertek of Herndon VA, with Ball z Engineering Unit built that demonstrated full mission lifetime (2 billion shots). z Laser is Nd:YAG in a zigzag slab with 192 diode bar pumps z Utilizes a KD*P Q-switch (20 ns pulses) and a KTP frequency Doubler z 110 mJ/pulse for each color @ 20 Hz z Spectral linewidth (Multi-transverse mode) z 532 nm Output polarized to > 1000:1 z Conductive Cooling – Heaters/radiators z Ball designed Beam Expander Optics set laser divergence to approximately 100 microrad z Weight 35 kg, uses 100 W (incl. Heaters) z Redundant Lasers used – each designed for full mission life Laser Energy – Long-term Orbit Trend

140 CALIPSO Risk Reduction Laser 120 6% loss after 2.1B shots

100 Laser Adjustment Threshold

80

60 Minimum Energy Required to Meet Level 1 Requirements

Energy (milliJoules) 40

20 LOM #2 532nm LOM #2 1064nm 0 Apr, Aug, Dec, Apr, Aug, Dec, Apr, Aug, Dec, Apr, 2006 2006 2006 2007 2007 2007 2008 2008 2008 2009

March 15, 2007 • Trend is consistent with Risk Reduction Laser (RRL) • Slow decay is due to the diode lasers degrading – 15,200 used as “pumps” • Redundant second laser hasn’t been turned on, yet • Laser Power is adjustable – Running at 70%, so we still have 30 % margin • Laser Canister pressure decaying but looks acceptable for mission • Current trend indicates only one laser will be needed Aligning the Laser and Receiver Pointing

CALIOP Boresight Search and Align • Ball mechanisms and software 400 autonomously aligned the lidar 350 • Search completed in 4

300 minutes

250 • Align completed in 10 minutes 200 End Search 6/07/06 Start Search • Predicted align position agreed to 150 after manual move CALIPSO Lidar 130 µradHistory with of Positions actual After Boresight Aligns

Z Position(microradians) All positions 100 fall within a 12 microradian After Align, 6/07/06 160 radius circle After Second Align, 6/07/06 After Multiple Aligns, 6/12/06 Two questionalble results from the south end 50 After Align, 8/20/06 of the orbit on 6/21/06 are not included. 11/06/06 After Second Align, 8/20/06 Launch Position 155 8/20/06 0 6/12/06 0 50 100 150 200 250 300 350 400 450 500 Y Position (microradians) 150 • Stability of full lidar system checked 145 9/21/06

monthly 6/7/06

• Relative pointing has been Z Angle (microradians) 140 stable to < 10 µrad over last three Initial Align

135 Parameter changes before 8/20 Align: months ABMAlignDelta from 6.25 to 3.75 (10 to 6 microrad) ABMAlignNumFrames from 50 to 80 ABMAlignAttempts from 3 to 4 • Signal stability over multiple 130 orbits is better than 1% (night) 130 135 140 145 150 155 160 165 Y Angle (microradians) Study of Lidar Stability

Polar Vortex over Antarctica

z Rayleigh (Molecular) scattering from 27- 40 km altitude (June)

z Ground track starts over Northern Hemisphere and goes to Southern

z Lidar is temperature cycling – cooling

z Signal does not repeat on itself – possible slight alignment shift CALIPSO Laser output as it passes over Nederland

Photograph by Gregg Hendry 7/14/06 More Information about CALIPSO at: http://www-calipso.larc.nasa.gov http://smsc.cnes.fr/CALIPSO/ http://calipsooutreach.hamptonu.edu/ http://www.n2yo.com/?s=29108 Also See: http://giovanni.gsfc.nasa.gov http://www.nuforc.org/webreports/055/S55212.html Some Lidars in Space

z Apollo 15 1971 Ranging z Clementine 1994 Ranging (Mapped the Moon) z LITE 1994 Profiling (Shuttle) z Balkan 1995 Profiling z NEAR 1996 Ranging z SLA-01 1996 Ranging z MOLA II 1996 Ranging (Mapped Mars) z SLA-02 1997 Ranging z Icesat/GLAS 2003 Ranging/Profiling (Icesheets) z MLA 2004 Ranging (Mercury) z CALIPSO 2006 Profiling of Aerosols/Clouds z Phoenix 9/2007 Profiling Dust (Mars) z LOLA 2008 Ranging (Moon) z ADM-Aladin 2009 Wind Measurements (ESA)