Imaging Technique of the DISR Camera on the Huygens Lander J.R. Kramm 1, H.U. Keller 1, R. Bredthauer 2 and M. Tomasko 3 1 Max-Planck-Institut für Sonnensystemforschung Katlenburg-Lindau, Germany 2 Semiconductor Technology Associates, Inc. San Juan Capistrano, CA 3 Lunear and Planetary Laboratory, University of Arizona, Tucson, AZ MPS, June 20, 2005

Descent Imager/ Spectral Radiometer (DISR) Instrument Consortium Scientific Objectives Medium and high-resolutions Imaging of the surface of Titan Medium and high-resolutions Imaging of the surface of Titan Imaging of clouds and haze at Titan Imaging of clouds and haze at Titan Spectral investigations, 350 – 1700 nm Spectral investigations, 350 – 1700 nm Solar Aureole, 500 and 935 nm, horiz. and vertical polarization Solar Aureole, 500 and 935 nm, horiz. and vertical polarization Instrument responsibility: Manufacturing contractor: CCD Imager & electronics: CCD contractor: H/W compression: Infrared detector: LPL, Tucson, AZ Lockheed Martin, Denver, CO Max-Planck-Institut, Germany Loral, Newport Beach, CA Univ. Braunschweig, Germany Observatoire de Paris, France

DISR Instrument Characteristics 14 optical apertures total 14 optical apertures total 9 optical apertures to 1 CCD detector 9 optical apertures to 1 CCD detector 1.1 Watt for the CCD, 512 x 256 pixels 1.1 Watt for the CCD, 512 x 256 pixels Date rate:8 kbit/s, ~ 1 bit per pixel Date rate:8 kbit/s, ~ 1 bit per pixel 6 years for design, production and calibr. 6 years for design, production and calibr. 7.5 years travel time to Titan, years travel time to Titan, min total operation time envisaged 150 min total operation time envisaged 220 min operation completed 220 min operation completed 600 Images acquired + Spectra etc. 600 Images acquired + Spectra etc.

DISR Instrument on the Huygens Probe

The Loral Max-Planck CCD Approach Dedicated buried channel design for DISR / Max-PlanckDedicated buried channel design for DISR / Max-Planck Front side illuminated Frame Transfer CCDFront side illuminated Frame Transfer CCD 2 phase MPP clocking2 phase MPP clocking Image and Memory sections 256 rows, 512 (+8 dark) columnsImage and Memory sections 256 rows, 512 (+8 dark) columns Gated lateral anti-blooming, also electronic shutterGated lateral anti-blooming, also electronic shutter 23 μ pixel pitch (17μ x 23μ active area)23 μ pixel pitch (17μ x 23μ active area) Pixel capacity 150,000 e‾ (100,000 e‾ used)Pixel capacity 150,000 e‾ (100,000 e‾ used) QE up to 50 %, CTE = QE up to 50 %, CTE = Line transfer 2 μs/line low image smear on shiftLine transfer 2 μs/line low image smear on shift Single stage output amplifier, 5- 8 electronsSingle stage output amplifier, kHz OP16 JFET preamp on Sensor Head Board - (MPS)OP16 JFET preamp on Sensor Head Board - (MPS) Electronics Assembly holds CDS, clock drivers and 12 bit ADCElectronics Assembly holds CDS, clock drivers and 12 bit ADC CCD shielded by 4 mm tungsten to prevent < 62 MeV protonsCCD shielded by 4 mm tungsten to prevent < 62 MeV protons DISR CCD was also used for Imager for Mars Pathfinder (IMP) and 2x for Mars Polar Lander (Stereo and Robotic Arm Camera)DISR CCD was also used for Imager for Mars Pathfinder (IMP) and 2x for Mars Polar Lander (Stereo and Robotic Arm Camera)

DISR CCD Layout

The DISR Optical System with CCD

DISR Camera Head

DISR Bias Frames Imager Bias Frames, 0 ms exposure, 260 K, and MRI Column Amplitude from 1994, 2000, 2005 Dark charge increase approx. 60x upon proton irradiation from a plutonium heater 10 cm apart from the Sensor Head ( ).

CCD Operation Temperature Profile and Dark Charge Temperature Scale

DISR In-flight Flat Field Matrices

In-flight Irradiation Effects In-flight proton irradiation from a nuclear heater located close to the CCD (~10 cm) Resulting effects: Perfect thermal balance established Dark charge increase about 60x with minor effects (low temperature, short exposure times, 7 to 50 ms) CTE degradation