John Spencer Lowell Observatory

1
Galilean Satellite Science with New Horizons

• John SpencerLowell Observatory
• DPS Meeting, Monterey, Sept. 4th 2003

2
Galilean Satellite Opportunities

• No close flybys!
• Closest satellite approach depends on launch date
• For most launch dates, Callisto is on the wrong
  side of Jupiter
• Ganymede is occasionally on the right side
• Doesnt matter much for Europa, Io
• Closest possible approaches
• 23 RJ for Europa and Ganymede, or
• 19 RJ for Callisto (unlikely)
• Likely average distance at perijove 32 RJ 2.2
  x 106 km
• Spacecraft tangential speed 25 RJ / day
• Geometry changes quickly relative to satellite
  orbital periods

3
Resolution

• 32 RJ

4
Example Io resolution near c/a

• Flyby is sufficiently distant that resolution
  varies little with orbital longitude for Io and
  Europa
• Viewing geometry changes relatively slowly
• Can observe most of Io at similar geometry
• Geometry changes significantly during one orbit
  of the other satellites, however

5
All Galilean Satellites

• Calibration of all instruments, esp. if/when
  reproduce Earth-based geometry
• MVIC
• Unique phase coverage for multicolor photometry
• Bolometric albedos (esp. important for Io,
  Europa)
• Surface texture
• Multicolor change detection on Io, (Europa)
• Eclipse imaging of atmospheric emissions
• LORRI
• Shape, global topography
• Image limb terminator with consistent
  resolution/geometry and good longitudinal
  resolution
• LEISA
• Better spectral resolution than NIMS
• Unique spatial/spectral coverage- new species?
• Nature of dark material on Europa
• Ice temperatures on the icy satellites
• Better spatial resolution than NIMS at many
  longitudes
• IR phase function- bolometric albedo

6
Io-specific

• Global inventory of topography (LORRI)
• Large topographic changes??? (LORRI)
• Eclipse, nightside imaging of hot spots (MVIC,
  LEISA)
• Global hot spot inventory (LEISA)
• Plume inventory (MVIC, LORRI)
• 2.12 micron SO2 band (spatial distribution,
  thermometer?) (LEISA)
• 1 micron mystery band (better global mapping than
  NIMS (LEISA)

7
Small Satellites, Rings

• Astrometry?
• Spectroscopy (no useful NIMS spectra of small
  satellites)
• Phase angle coverage (poss. including
  opposition?)
• Temporal variability of the rings
• Outer irregular satellites

8
Summary

• Lots of science to do- will likely be too much
  competition for the timeline, downlink, fuel to
  do it all
• Need to prioritize
• How rapidly can we move between targets? How
  much fuel will this take?
• Saturation issues...