New Horizons at Io: Science Goals and Observation Plan John Spencer SwRI Jeff Moore, NASA-Ames Debi Rose and the New Horizons team Io Workshop Redlands, June 6 th 2006

Remote Sensing Instrument Suite  Closest approach (~32 R J ): Instrument Resolution, rad Resolution, km/pix Pixels across Io MVIC (0.48, 0.62, 0.85, 0.89 micron color imaging) 2e LORRI ( micron panchromatic imaging) 5e LEISA ( micron spectra) 6.2e ALICE (0.05 – 0.18 micron spectra) 5e < 1

Range vs. time

Phase vs. Time

Sub-S/C Longitude vs. Time

DSN Plan near Closest Approach

Science Overview Observation Categories Jupiter AtmosphereJupiter Atmosphere IoIo Icy Galilean SatellitesIcy Galilean Satellites MagnetosphereMagnetosphere RingsRings Small SatellitesSmall Satellites SceneryScenery

Io: Surface  Surface albedo changes since Galileo Global panchromatic LORRI coverage at ~12 km/pix (Ihires01 – 06)Global panchromatic LORRI coverage at ~12 km/pix (Ihires01 – 06) MVIC color coverage of Jupiter- facing hemisphere at ~60 km/pix (Ishine01, 02)MVIC color coverage of Jupiter- facing hemisphere at ~60 km/pix (Ishine01, 02)  Global topography from limb fits Better longitude coverage than Galileo(?)Better longitude coverage than Galileo(?)  Nature of the broad 1.2 μm absorption band? Global distribution of 1.98, 2.12 μm SO 2 bands? Global 1.25 – 2.5 μm reflectance spectroscopy (Ihiresir01 – 04)Global 1.25 – 2.5 μm reflectance spectroscopy (Ihiresir01 – 04)

Io: Plumes  Distribution, morphology, lifetime, short-term variability, and particle size distribution of the plumes Global panchromatic LORRI coverage for plumes higher than ~60 km at high phase angles (Initemon01 – 14)Global panchromatic LORRI coverage for plumes higher than ~60 km at high phase angles (Initemon01 – 14) Color MVIC images of selected plumes (e.g. Pele, Prometheus, Tvashtar) on the limb (Ihires01, 05, Initemon05, Ieclipse05)Color MVIC images of selected plumes (e.g. Pele, Prometheus, Tvashtar) on the limb (Ihires01, 05, Initemon05, Ieclipse05)  Short-term plume variability: correlation of plumes with Jovian dust streams? Multiple LORRI observations of the same longitudes on approach and departure, with an emphasis on Pele (Isunmon01 – 09, Initemon01 – 14)Multiple LORRI observations of the same longitudes on approach and departure, with an emphasis on Pele (Isunmon01 – 09, Initemon01 – 14)

Io: Hot Spots  Temperatures and global distribution of the hottest hot spots? Temperatures constrain the magma composition Global eclipse and nightside imaging (Ieclipse01 – 05, Ihiresir04, Ishine01, 02)Global eclipse and nightside imaging (Ieclipse01 – 05, Ihiresir04, Ishine01, 02) LORRI (0.4 – 1.0μm panchromatic, ~12 km resolution)LORRI (0.4 – 1.0μm panchromatic, ~12 km resolution) MVIC (0.4 – 1.0 μm, ~50 km resolution)MVIC (0.4 – 1.0 μm, ~50 km resolution) LEISA (1.25 – 2.5 μm, ~150 km resolution)LEISA (1.25 – 2.5 μm, ~150 km resolution) Io in eclipse, 2.2 μm, 100 km resn, de Pater et al. 2004

Io: Auroral Emissions  Interaction of Io’s atmosphere with the Jovian plasma ~40 Alice spectra of FUV neutral O, S emissions at many geometries (every Io visit)~40 Alice spectra of FUV neutral O, S emissions at many geometries (every Io visit) Eclipse imaging of visible SO 2, O, S, Na emissions (Ieclipse01 – 05)Eclipse imaging of visible SO 2, O, S, Na emissions (Ieclipse01 – 05)  Thermal excitation of volcanic gases Eclipse imaging of 1.7 μm SO emission (Ieclipse01 – 05)Eclipse imaging of 1.7 μm SO emission (Ieclipse01 – 05)

Io: Neutral bound atmosphere  Does Io’s atmosphere collapse at night? Occultation of HD (Iocc01, -2.1 days)Occultation of HD (Iocc01, -2.1 days) 55 o S latitude55 o S latitude Phase angle 25 o : see atmosphere at 7:40 am and 7:40 pmPhase angle 25 o : see atmosphere at 7:40 am and 7:40 pm Bright star: excellent S/N, strong absorption expectedBright star: excellent S/N, strong absorption expected First ever observation of Io’s nightside atmosphereFirst ever observation of Io’s nightside atmosphere Occultation of HD (Iocc02, -0.0 days)Occultation of HD (Iocc02, -0.0 days) EquatorialEquatorial Phase 87 o : Noon/midnightPhase 87 o : Noon/midnight Very low S/NVery low S/N Limb transmission, 1.6 x cm -2 SO 2 Star counts in bottom scale height Simulated Occultation of V4387 Sgr

Io Observation Sequence

Io Color and Near-IR Hi-Res Longitudinal Coverage  Emission angle < 70 o  MVIC (yellow): ~50 km pixels  LEISA (blue=dayside, orange=nightside): ~170 km pixels

Plume coverage  Height > 30 km, phase > 102

Plume coverage  Height > 85 km, phase > 102

Expected S/N  Generally use minimum integration time to avoid smear (except for auroral emissions).  Sensitivity is excellent anyway… Expected S/N LORRI (0.1 sec) MVIC (1000 murad/sec) LEISA (450 murad/sec) TargetBlueRedCH4NIR1.2µm2.5µm “Bright Pele” hot spot Satn. “Faint Pele” hot spot “Hot Pillan” hot spot Satn. Faint Plume, I/F=2e-45 Io in Jupiter shine, I/F=5.6e

Kodak Moments  What are the scenic properties of the Jupiter system? LORRI images of selected scenic conjunctions and alignments of the satellites (Jkodak01, 02, Ikodak01, Ekodak01, Gkodak01, Ckodak01)LORRI images of selected scenic conjunctions and alignments of the satellites (Jkodak01, 02, Ikodak01, Ekodak01, Gkodak01, Ckodak01)

Groundbased support  IRTF observations of volcanos, starting in August 2006 (gap from early October to late December)  Applied for VLT time for high spatial resolution volcano imaging and plume spectroscopy near c/a in February 2007