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The Cassini-Huygens Mission to Saturn and Titan. Professor John C. Zarnecki. Saturn and Titan. Most distant planet visible with the naked eye 2 nd largest planet in the solar system Gas giant – primarily Hydrogen and Helium 34 known moons at present
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The Cassini-Huygens Mission to Saturn and Titan Professor John C. Zarnecki RAeS – 22nd March 2005
Saturn and Titan RAeS – 22nd March 2005
Most distant planet visible with the naked eye 2nd largest planet in the solar system Gas giant – primarily Hydrogen and Helium 34 known moons at present 1.5 billion km mean distance from the sun, 10 x more distant than the Earth Unique complex ring system Saturn RAeS – 22nd March 2005
Saturn’s largest moon Discovered by Christiaan Huygens in 1655 Diameter of 5150 km Atmospheric pressure of 1.5 bar Surface temperature ~ 96 K (-177°C) Titan RAeS – 22nd March 2005
Only planetary satellite with atmosphere (column mass ~ 10 x value for Earth) Surface – obscured by photochemical haze Atmosphere – mainly N2 with CH4 and an array of hydrocarbons and nitriles Indirect evidence for surface seas/lakes (i.e. a methane ‘source’) A ‘primordial atmosphere’ (but frozen!) → an ancient earth? Why Titan? RAeS – 22nd March 2005
The Cassini/Huygens Mission RAeS – 22nd March 2005
The Cassini Spacecraft • Joint ESA/NASA mission • Launched 15th October 1997 • 6.7 m high • 2125 kg at launch • After a 7 year (4 billion km) journey, Cassini arrived at Saturn in July 2004. RAeS – 22nd March 2005
The Gravity Assist Trajectory RAeS – 22nd March 2005
Saturn Orbit Insertion RAeS – 22nd March 2005
The Huygens Probe • Determine atmospheric composition • Study aerosol properties and cloud physics • Characterise the upper atmosphere • Imaging the surface for the first time • Determine the physical properties of the surface material RAeS – 22nd March 2005
Industry • LogicaCMG – Mission critical on-board software, including Probe control software, Cassini/Huygens communications relay software and in flight software maintenance. • Martin Baker Space Systems – Parachute systems and related structural components, mechanisms and pyrotechnics. • Irvin Aerospace – Sub-contractor to Martin Baker responsible for definition of each of the three disk gap band parachutes. • IGG Component Technology - Centralised procurement and testing of electrical, electronic and electromechanical components. • SciSys – Mission control system development and operational support. RAeS – 22nd March 2005
Huygens Atmospheric Structure Instrument (HASI) Fulchignoni, Paris, France. Gas Chromatograph Mass Spectrometer (GCMS) Niemann, NASA, USA Aerosol Collector and Pyrolyser (ACP) Israel, CNRS, France. Descent Imager/Spectral Radiometer (DISR) Tomasko, Arizona, USA Doppler Wind Experiment (DWE) Bird, Bonn, USA Surface Science Package (SSP) Zarnecki, OU, UK. List of Instruments RAeS – 22nd March 2005
The Surface Science Package(SSP) RAeS – 22nd March 2005
SSP Flight Integration RAeS – 22nd March 2005
SSP Sensor Description RAeS – 22nd March 2005
Selected Properties Measured by SSP RAeS – 22nd March 2005
SOLID LIQUID MUD ATMOSPHERE RAeS – 22nd March 2005
ACC-I (Internal Accelerometer) • Piezoelectric accelerometer • Max ~100 g detection • Impact dynamics measurement (deceleration) RAeS – 22nd March 2005
ACC-E (Penetrometer) • Piezoelectric force transducer • Protrudes from probe base • First instrument to touch Titan’s surface • Impact measurement of penetration through the surface layer (mechanical properties of the surface) RAeS – 22nd March 2005
TIL (Probe Attitude) • Measures tilt relative to 1 axis • Electrolytic liquid in a glass vial • Fluid movement relative to electrodes → tilt angle RAeS – 22nd March 2005
API-V (Speed of Sound) • 2 piezoelectric transducers generate ultrasonic pulse • Alternate Tx/Rx mode • Arranged facing each other • Time taken for pulse to be detected → speed of sound in the Titan atmosphere (molecular mass) RAeS – 22nd March 2005
API-S (Sounder) • 10 resonant piezoelectric plates • Simultaneously form a 20° acoustic beam • Orientated towards the surface • Surface profile echoes • Ocean/lake sounder RAeS – 22nd March 2005
THP (Thermal Properties) • Thin wire technique • 50 µm Pt wire pulsed with high current • RΩ(t) measured • Thermal conductivity derived (gas mixture components) RAeS – 22nd March 2005
DEN (Density) • Archimedes’ principle • Float suspended in chamber • Buoyancy in immersed liquid measured by strain gauges → density RAeS – 22nd March 2005
REF (Refractometer) • Critical angle refractometer • Linear photodiode array and specially designed prism • Refractive index of immersed liquid measured (light-dark transition) RAeS – 22nd March 2005
PER (Permittivity and Conductivity) • Stacked parallel plates • Capacitance measured • Permittivity and conductivity of the liquid measured RAeS – 22nd March 2005
Landing On Titan RAeS – 22nd March 2005
Arrival and Descent RAeS – 22nd March 2005
Possible Landing Scenarios RAeS – 22nd March 2005
High Altitude Images Altitude 16.2 km, 40m per pixel resolution Altitude 8 km, 20m per pixel resolution Credits: ESA/NASA/University of Arizona RAeS – 22nd March 2005
High Altitude Images Altitude 16.2 km, 40 m per pixel resolution Credits: ESA/NASA/University of Arizona RAeS – 22nd March 2005
A View from 10 km Credits: ESA/NASA/University of Arizona RAeS – 22nd March 2005
Views at the surface Credits: ESA/NASA/University of Arizona RAeS – 22nd March 2005
The Impact on the Surface RAeS – 22nd March 2005
The Impact on the Surface RAeS – 22nd March 2005
Over 100 vertical and oblique drops into 16 different substrate materials. Impact Simulations Coarse Gravel Sand SiliBeads Crème Brulee Drop Test Rig RAeS – 22nd March 2005
Impact Simulations RAeS – 22nd March 2005
Impact Simulations RAeS – 22nd March 2005
ACC-I (deceleration):35ms deceleration pulse, peak 15g – Huygens probe decelerated over circa 16cm; Model comparison suggests material with uniform strength vs. depth, ~10 N cm-2 ACC-E (penetration force):50N resistance with some variation – possibly a pebble strike, possible sub-surface granular structure on cm scale or finer Impact Dynamics – First Look RAeS – 22nd March 2005
API-S Surface Detection RAeS – 22nd March 2005
API-V Speed of sound increases with temperature at lower altitude RAeS – 22nd March 2005
SSP has received ALL of its Science Data via Channel B. All SSP sensors have given the expected output for the atmospheric and surface conditions encountered. We have data up to T0 + 13,046secs (3hrs, 37mins, 26secs). Data from surface for 1hr, 9 mins, 36secs SSP Data Summary RAeS – 22nd March 2005
Huygens carrier at Green Bank, Mk5 VLBI Doppler (wind and more….) measurements L.Gurvits and the Huygens VLBI Tracking Team 17 January 2005 RAeS – 22nd March 2005
SSP Science Team Huygens Science Team ESA NASA Polish Academy of Sciences University of Manchester Rutherford Appleton Laboratory Particle Physics and Astronomy Research Council Acknowledgements RAeS – 22nd March 2005