Wavelength Trades for Viewing Titan’s Surface: Can JET’s Science Objectives be Met with a 2-Micron Camera? Jason W. Barnes Associate Professor of Physics University of Idaho Shannon MacKenzie, Eliot Young JET Team Meeting 2014 March 27 JPL, Pasadena, CA

Motivations Why the old camera is better: At 5um, less atmospheric scattering = clearer images Direct illumination at 5um means photoclinometry Direct illumination at 5um means more interpretable images Clearly going to work – no need to spend proposal pages Sharper imaging leads to better stereo Simultaneous 4-colors 5um can see specular reflections Why a 2-um optimized camera is better: It’s cheaper

Motivations Why the old camera is better: At 5um, less atmospheric scattering = clearer images Direct illumination at 5um means photoclinometry Direct illumination at 5um means more interpretable images Clearly going to work – no need to spend proposal pages Sharper imaging leads to better stereo Simultaneous 4-colors 5um can see specular reflections Why a 2-um optimized camera is better: It’s cheaper. Why? Smaller aperture for diffraction limit = lower mass More light from the Sun at 2um means smaller aperture 2um = off the shelf detector 2um = less thermal background and instrument effects Can regain some color science from filter wheel

Direct Total

Conclusions 2um camera instead of the baseline TIGER design could achieve a decent fraction of the scientific objectives. Needs many more photons, but there are more at 2um to work with. Also will need very careful calibration scheme, potentially tricky and severe image processing on the ground (but we can push that money into Phase E which isn’t our responsibility anymore!) I still want the original TIGER camera. But if we can’t fit under the cost cap with it, I do think that a 2um camera is worth considering as a threshold.