NH at Jupiter, Planning the Jupiter encounter Options

[john_s]

I think the Jupiter encounter deserves its own thread.

I've just been taking a first look at the Jupiter encounter geometry. You can do the same using Mark Showalter's excellent on-line ephemeris tools at the PDS rings node, which by good fortune happens to include a New Horizons ephemeris (calculated over a year ago) for our actual launch date, January 19th. We'll have an updated ephemeris soon, but this one's already good enough for planning. As Roby72 noted in the Star 48 thread, the satellites are (annoyingly) all on the opposite side of Jupiter at closest approach. We'll still get good views of all sides of Io because Io rotates in only 1.8 days and we'll be pretty close to Jupiter for that long. We'll get fairly good coverage on Europa too, for the same reason. But we won't get very close to Ganymede or Callisto. Luckily Io is our highest priority satellite target and Europa is next, so we'll do OK.

[Roby72]

John,

yes the day before (or after), Io must be on the right side of the planet, but I think the high speed of NH makes the distance about equal than on encounter day at the other side (about 2.5 Mio km). Resolution for LORRI (bw imager) should be about 12 km, for RALPH (color) about 50km) This would be nice for plume searching and is about 5 times more resolution in case of LORRI than Cassini had at its Jupiter encounter in Dec. 2000.

Robert

[ljk4-1]

Any chance NH could image Europa well enough to see if any surface features have changed/moved since Galileo?

[john_s]

Any chance NH could image Europa well enough to see if any surface features have changed/moved since Galileo?

We'll be looking at Europa but not specifically for that purpose- our images will be far lower resolution than Voyager's and no changes were seen between Voyager and Galileo even at Voyager resolution, and over a longer timespan than between Galileo and NH. Our main goal in imaging Europa will be to look at the peculiar large, shallow, depressions that were seen by Galileo near the terminator- it's one area where we can improve over Galileo. Plus we'll be observing Europa's auroral emissions in Jupiter eclipse.

By the way, here's a table I just sent to the science team, showing the timing and geometry of various significant events during the encounter. Times are spacecraft times, and the numbers will change just a bit once we get a final ephemeris. I've only calculated the times of the eclipses of each satellite that occur closest to the spacecraft- there are many more at greater ranges. "UT" means Universal Time, "mrad" means the angular diameter in milliradians, and "Sub-S/C Lon" means the sub-spacecraft longitude. I couldn't figure out how to align the columns properly without replacing all the spaces with underscores...


---------------------------------------------------------------------------
____________________Range___Diam__Solar__Sub-
____Date_______UT___(km)___(mrad)_Phase_S/C_Lon__Event
---------------------------------------------------------------------------
February_25__09:45_6334186__0.831___11____349____Ganymede eclipse ingress
February_25__11:45_6222615__0.846___12____352____Ganymede eclipse egress
February_27__10:46_3074450__1.021___40____315____Europa eclipse ingress
February_27__13:18_3045261__1.030___45____321____Europa eclipse egress
February_27__14:20_2734370__1.331___48____303____Io Eclipse ingress
February_27__16:28_2758131__1.320___53____316____Io Eclipse egress
February_28__02:00_2957815__1.061___72____347____Europa closest approach
February_28__05:00_2304575_61.920___82___________Jupiter closest approach
February_28__06:00_3029556__1.737__102_____41____Ganymede closestapproach
February_28__06:30_4153289__1.156___81____353____Callisto closest approach
February_28__22:00_2260221__1.610__118____141____Io_closest approach
___March__1__08:48_2748816__1.324__120____231____Io_eclipse ingress
___March__1__10:58_2951842__1.233__121____248____Io_eclipse ingress
---------------------------------------------------------------------------


John.

[ljk4-1]

We'll be looking at Europa but not specifically for that purpose- our images will be far lower resolution than Voyager's and no changes were seen between Voyager and Galileo even at Voyager resolution, and over a longer timespan than between Galileo and NH.  Our main goal in imaging Europa will be to look at the peculiar large, shallow, depressions that were seen by Galileo near the terminator- it's one area where we can improve over Galileo.  Plus we'll be observing Europa's auroral emissions in Jupiter eclipse.

John.

Thank you for the information, John. Would New Horizons be able to look for any possible geysers from Europa as well? Might be good practice for similar events in the Pluto system, too.