1. INMS Quarterly Report May - July, 2006 Submitted by J. Hunter Waite and the INMS Science and Operations Teams

2. INMS quarterly report: May-July, 2006 Science highlights - T16 –Highest signal to noise mass spectra to date Discovery of toluene in the upper atmosphere Positive identification of benzene and its altitude and spatial variation Comparable complexity from solar-euv-produced ionosphere to that of the T5 particle produce ionosphere –Sharp exospheric temperature latitudinal gradient between mid and high latitudes

3. Benzene and Toluene Forward Model Benzene Toluene

4. Hydrazine By-Products from AACS Thrusters 12 CH 4 from Titan 13 CH 4 from Titan + NH 3 from Thruster H 2 O from Thruster

6. N2 and CH4 densities measured by INMS during T16. Red are inbound data, blue are outbound. The solid curves are best fit model (judged by eye). The CH4 mole fraction at 950 km is set to 1.4% (equal to the GCMS value). The model has a thermospheric temperature of 133 K and an eddy diffusion coefficient of 6E8 cm2s-1. The CH4 escape flux is assumed to be zero.

7. INMS Refurbished Engineering Unit (REU) Sensor Calibration Setup uses INMS sensor with laboratory electronics, flight pulse counter and flight quadrupole mass analyzer systems Setup that can be used periodically to explore sensor related questions for the rest of the mission Thermal energy gas, ion and neutral beam testing available on 2 vacuum systems Current activity is thermal gas calibration Two sets of filaments, two ion sources Gases used-- N 2,Ar,He,H 2,Kr,CH 4,C 2 H 4,C 2 H 2 (Flight Unit) Ne,CO,CO 2,C 2 H 6,C 3 H 8,C 6 H 6, 15 N 15 N, 13 CH 4 Gas mass peak sensitivities and fragmentation patterns generated; sensitivity changes tracked Future activity: exotic gases and neutral beam testing (funding permitting) Responsibility: Goddard Space Flight Center INMS Sensor, Lab Electronics, Software Test Design Overall Operation of Sensor & Vacuum Systems (2) University of Michigan Data Processing, Archiving Routine Sensor Operation University of Arizona Data Processing Routine Sensor operation GSFC & University of Arizona Generation of exotic gases (HCN, C 2 N 2, C 2 H 4 )

8. INMS Refurbished Engineering Unit (REU) Sensor Calibration Ethane (C 2 H 4) Ion beam used to verify switching lens energy programming similar to that used for the flight unit Tracking of sensitivity for N 2, to be used for normalization later

9. INMS Operations INMS operations are nominal. We are planning to load version 10.0 of the INMS FSW in the next quarter. All equipment has been shipped from University of Michigan to SwRI and is presently being reconfigured. The INMS SOPC is operable. Calibration of the refurbished Engineering Unit is proceeding.

10. Extended Mission Planning INMS Team has created a basic set of criteria to guide trajectory studies. INMS operations team has current trajectories to determine which class of XM tour best suits our needs INMS has been reviewing the WIKI site for relevant content, and adding where necessary.

11. INMS quarterly report: January-April, 2006 Science plans –Upcoming INMS measurements of Titan’s atmosphere on T17 and T18 will continue to investigate the variability of Titan’s atmosphere in hopes of setting more definitive guidelines for the safe altitude of future Titan flybys. –Excellent INMS measurements of the atmosphere from the recent flyby of Enceladus suggest that a close flyby (~25 km) planned for orbit 061 with INMS in the ram direction will allow a definitive determination of the atmospheric composition including a measurement of the D/H and 14 N/ 15 N ratios.

12. INMS quarterly report: January-April, 2006 Science and operations planning –INMS measurements of Titan’s atmosphere on T17 and T18 will be used to update the TAMWG model of Titan’s atmosphere in hopes of setting more definitive guidelines for the safe altitude of future Titan flybys. –INMS team members are supporting four separate groups planning for the extended mission: Titan - Yelle Icy satellites - McNutt/Waite MAPS - Luhmann Rings - Cravens

13. INMS quarterly report: Talks & posters 1.V. Vuitton, R.V. Yelle and V. G. Anicich, Evidence for nitrogen-bearing molecules in Titan’s upper atmosphere, XVIIIèmes Rencontres de Blois, Blois, France, 2006.

14. INMS papers: January - April, 2006 1. Waite, J. H., Jr., M. Combi, W.-H. Ip, T. E. Cravens, R. L. McNutt, Jr., W. Kasprzak, R. Yelle, J. Luhmann, H. Niemann, D. Gell, B. Magee, G. Fletcher, J. Lunine, and W.-L. Tseng, Cassini Ion and Neutral Mass Spectrometer: Enceladus plume composition and structure, Science, in press, 2006. 2.Yelle, R., Borggren, N., de la Haye, V., Kasprzak, W. T., Niemann, N. B., Müller- Wodarg, and Waite, J. H., Jr., Titan atmospheric structure, J. Geophys. Res., in press, 2006. 3.Luhmann, J. G., R. E. Johnson, R. L. Tokar, S. A. Ledvina, T. E. Cravens, A model of the ionosphere of Saturn's rings and its implications, Icarus, 181 (2), 465-474, 2006. 4.Johnson, R. E., J. G. Luhmann, R. L. Tokar, M. Bouhram, J. J. Berthelier, E. C. Sittler, J. F. Cooper, T. W. Hill, H. T. Smith, M. Michael, M. Liu, F. J. Crary, and D. T. Young, Production, ionization and redistribution of O 2 in Saturn's ring atmosphere, Icarus, 180, 393, 2006. 5.Cravens, T. E., et al., The composition of Titan's ionosphere, Geophys. Res. Lett., in press, 2006. 6.Mueller-Wodarg, I. C. F., R. V. Yelle, N. Borggren, and J. H. Waite, Waves and horizontal structures in Titan’s thermosphere, Icarus, in preparation, 2006. 7.Ledvina, S., et al., Effects of Titan's induced magnetosphere on exospheric charge- exchange and ENA production, Icarus, submitted, 2006.