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.

[hendric]

I created a spreadsheet and imported the ephermis for a few weeks around closest approach, for every 20 minutes in the enounter. Best one so far is:
MJD Objects Notes
54161.44 IO & EUROPA Really close pass

Try adding a few hundredths of a MJD either way. When using the Jupiter Viewer, enter MJD as MJD 545161.44.

There are a few others from further away. I want to redo the ephermis +- a day to closest approach to see if I am missing any due to the 20 minute step size.

I'll post the spreadsheet once I'm done, promise!

Attached thumbnail(s)

 

[hendric]

OK, so there were a few additional close Io and Amalthea passes. Looking at the graphs, the majority of passes are Io & Amalthea, with a few others, mostly with Amalthea. The speedy little moon gets around!

MJD Bodies Comments
54149.68056 IO & AMALTHEA Europa is just out of view to the NW, good view of the rings
54149.8888 IO & AMALTHEA Thebe is left of Amalthea, IO is pretty far away
54150.98611 IO & EUROPA Far pass
54157.925 IO & JUPITER Io grazes the north side of jupiter, leaving J disk on dark side
54158.943 IO & JUPITER Io goes behind jupiter on the dark side
54159.365 EUROPA & JUPITER Europa grazes the southern dark side of Jupiter
54160.12 IO & JUPITER Crescent IO in front of dark side Jupiter, emerges few minutes later
54160.12 AMALTHEA & JUPITER Crescent Amalthea in front of dark side of Jupiter, emerges a few minutes later
54161.042 IO & JUPITER Io disappers behind jupiter on the dark side, with the rings visible and in shadow. Encounter with Io and Rings starts earlier
54161.43646 IO & EUROPA Really close pass!!!
54161.85 EUROPA & AMALTHEA Rings are between them
54161.97083 IO & AMALTHEA Rings are between them, with Adrastea possible
54162.85365 IO & AMALTHEA Close pass, rings and Metis visible, long encounter!
54165.125 IO & EUROPA Small crescents for both
54165.70833 IO & AMALTHEA Rings & jupiter, but distance function shows a bump, so could be interesting encounter
54168.70833 IO & EUROPA Pretty far pass, but in the same field
54170.94633 IO & EUROPA Amalthea emerges from behind Jupiter, might make an interesting appearance, all objects showing thin crescents

I had to do a manual search for Jupiter events, and gave up after a bit.

Unfortunately, the spreadsheet is over 20 MB, so I can't post the full thing. Here is a PDF of the charts, and a cut-down spreadsheet that you can enter the data in yourself. Some notes:

1. You have to modify the RA so that it is monotonic. What does that mean? When scrolling down, if you get to a set of entries that go from +~24 to ~0, then you need to change the RA(corr) column to (RA+24) to keep it linear.
2. RA is multiplied by 15, to get something vaguely representing degrees.

Any other questions, or if you want the full spreadsheet, feel free to ask.

Attached File(s)

 ephem_jup_5946.pdf ( 868.6K ) Number of downloads: 731