Nine Years of Atmospheric Remote Sensing with SCIAMACHY – Instrument Performance Gottwald, Krieg, Lichtenberg, Slijkhuis – DLR-IMF Noël, Bramstedt, Bovensmann, von Savigny – IUP, Univ. of Bremen Snel, Krijger – SRON

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 2 Topics instrument operations instrument status and performance mission extension

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 3 SCIAMACHY on ENVISAT 26 m  10 m  5 m Satellite dimensions 8.2 tSatellite mass 10No. of instruments minOrbit period 10 a.m. (sun-synchronous)Descending node crossing 800 kmMean altitude 98.5°Inclination ENVISAT nominal mission profile

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 4 Instrument – Optical Assembly Level 1: channels 1 & 2 (UV) entrance optics calibration unit pre-disperser prism Level 2: channels 3 & 4 (VIS) channel 5 (NIR) channels 6-8 (SWIR)

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 5 Viewing Geometries scientific nadir limb sun occultation moon occultation calibration & monitoring sun occultation moon occultation subsolar internal calibration lamps (WLS, SLS)

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 6 Instrument – Thermal Subsystems Optical Bench Module (OBM) cooled via RAD A T = -17.6°C to -18.2°C active thermal control (ATC) detectors cooled via SCIAMACHY Radiant Cooler (SRC) T  195 K – 230 K (channels 1-6) T  140 K – 160 K (channels 7 & 8) open loop heater control (TC) detectors decontamination SRC cooling capacity may degrade because of contamination decontamination heaters to raise T on reflecting surface (if needed) decontamination brings T of OBM and detectors close to 0°C  contaminants are removed

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 7 Operations instrument operations are continuous highly autonomous implemented in states and timelines organised in mission scenarios limb/nadir on dayside sun occultation each orbit sub-solar every 3 rd day moon occultation whenever possible dedicated eclipse measurements calibration&monitoring measurements on daily, weekly and monthly timescales

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 8 instrument operation related information available via launch March 1, 2002 end nominal mission phase March 1, 2007 Instrument Status - Availability

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 9 Thermal Systems: ATC and OBM Temperature only small orbital variation of T OBM very stable orbital mean T OBM ATC degradation compensated by heater power adjustment

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 10 Thermal Systems: TC and Detector Temperatures temperature control via TC heaters TC system degrades detectors 1-6: K / year detectors 7 & 8: approx. 1 K ice layer effect

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 11 Life Limited Items mechanical items (neutral density filter, aperture stop, nadir calibration window) and thermal item (cryogenic heatpipe) have assigned in-flight activation budgets electrical items (WLS, SLS) have assigned in-flight switching budgets operations concept goal is not to exceed LLI limits

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 12 Optics - Throughput optical throughput channels 1-6 reduction of 3-4% per year in UV very stable in VIS, NIR & SWIR solar eclipse

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 13 channels 6+, 7, 8: 6% pixel loss / year  about 10-15% ‘good’ pixels by end 2013 in 7 & 8: throughput loss 1-2% / year due to ice layer (decontaminations are still an option to remove ice) Detectors - Degradation channel 2: detector material degradation (2% sensitivity loss / year)  25% loss by end 2013

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 14 Limb Tangent Height pointing knowledge essential for geolocation retrieval, particularly limb tangent heights continuos improvement over the mission lifetime: current limb tangent height accuracy about ° = m

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 15 mission in nominal ENVISAT orbit ended 22 October 2010 Mission Extension since then modified drifting orbit no inclination manoeuvres altitude lowered by 17 km instrument configuration successfully adapted to new orbit SCIAMACHY continues to deliver high quality data

IGARSS2011 > G. Lichtenberg > 28 July 2011 Slide 16 SCIAMACHY – Exploring the Changing Earth’s Atmosphere SCIAMACHY – The Need for Atmospheric Research from Space ENVISAT – SCIAMACHY’s Host The Instrument Instrument Operations Calibration and Monitoring SCIAMACHY In-Orbit Operations and Performance From Radiation Fields to Atmospheric Concentrations – Retrieval of Geophysical Parameters Data Processing and Products Validation SCIAMACHY’s View of the Changing Earth’s Environment