Juno development, launch, and cruise, Including Earth flyby imaging Oct 9 2013 Options

[volcanopele]

Well, if the camera sticks around till May 4, 2017, based on the trajectory in JPL Horizons, there is a nice encounter with Ganymede at 06:00 UTC on that day at a distance of 270,000 km when that satellite transits across Jupiter from Juno's perspective.

Attached thumbnail(s)

 

[IM4]

for those close-approach tables, you really need spice kernel files, but I believe that JPL Horizons also has this capability

Currently I am using custom "brute force"method. It has moderate accuracy but still suitable for event search. I can summarize my results as following "Top Lists", 5-10 closest approaches for every Galilean.

CODE

Name______Date___________CA_Dist (km)
Io    2017-Sep-24  17:18    141289
Io    2017-Jul-31  20:44    180270
Io    2017-Jun-07  00:10    217693
Io    2017-Apr-13  03:49    245136
Io    2017-Feb-17  07:16    279940
Io    2017-Apr-23  22:49    312179
Io    2016-Dec-24  10:44    312879
Io    2017-Jun-17  19:13    313812
Io    2017-Oct-05  11:57    321276
Io    2017-Aug-11  15:38    324122
Io    2017-Feb-28  02:33    330138
Io    2017-Aug-22  23:29    339674
Io    2017-Jan-04  06:14    341542

Europa    2017-Jul-31  14:58    110869
Europa    2017-Jul-20  18:37    224189
Europa    2017-Apr-01  21:46    230908
Europa    2017-Mar-22  01:44    266977
Europa    2016-Dec-02  04:38    348658
Europa    2016-Nov-21  08:40    355904
Europa    2017-Aug-11  09:54    382235
Europa    2016-Oct-31  02:45    453186
Europa    2017-Jul-09  21:34    453752
Europa    2017-Apr-12  16:05    455906

Ganymede    2017-Sep-24  06:52    149391
Ganymede    2017-Apr-12  16:14    168270
Ganymede    2017-May-04  09:14    216067
Ganymede    2016-Nov-20  19:02    372453
Ganymede    2016-Oct-30  02:09    400230
Ganymede    2017-Sep-02  11:54    410075

Callisto    2016-Dec-22  20:11    155386
Callisto    2016-Nov-19  14:44    232124
Callisto    2017-Jan-25  00:25    285824

Some interesting events are highlighted. Most promising encounter is one with Callisto (2016-Dec-22), close enough and just within first eight Juno's orbits. Assuming 3 degree FOV and 1024x1024 CCD, we may expect a spectacular view of that moon. Something like this:

[volcanopele]

Here is a nice overview from Celestia of Juno's orbital tour plus a nice shot from the first perijove shortly after (?) JOI:

Attached thumbnail(s)

 

[mcaplinger]

Assuming 3 degree FOV and 1024x1024 CCD, we may expect a spectacular view of that moon.

Sorry, but since Junocam has a 70-degree FOV none of these approaches is going to be spectacular. (All this was discussed upthread.) If there happened to be one closer than, say, 50,000 km, it might be worth doing, but even that's 40 km/pixel, only a 2-3x better than HST can get.

[IM4]

...but since Junocam has a 70-degree FOV...

Could you provide me with detailed specification for Junocam? In this thread I found only bits of information.
Anyways, we still have JIRAM imager. According to this presentation it has Pixel IFOV = 250 microrad, which is equivalent to spatial resolution of about 1 km/pixel for perijove passage (5000 km) - much more than Junocam has. So we still have a chance to obtain interesting images of the large moons.

[mcaplinger]

Could you provide me with detailed specification for Junocam?

See
http://www.unmannedspaceflight.com/index.p...st&p=131840 -- 4 km at 5000 km implies an IFOV of 800 urad/pxl.

[IM4]

4 km at 5000 km implies an IFOV of 800 urad/pxl.

Thanks.
I made another table of the best imaging opportunities: object name, date of the encounter, distance and maximum moon's image size in JIRAM and Junocam pixels. Here it is.

CODE

Name            Date            CA_Dist(km) JIRAM    Junocam
Ganymede    2017-Sep-24  06:52    149391    140,9    44
Ganymede    2017-Apr-12  16:14    168270    125,1    39,1
Callisto    2016-Dec-22  20:11    155386    123,6    38,6
Europa      2017-Jul-31  14:58    110869    113,2    35,4
Io          2017-Sep-24  17:18    141289    102,8    32,1
Ganymede    2017-May-04  09:14    216067    97,4     30,4
Callisto    2016-Nov-19  14:44    232124    82,7     25,8
Io          2017-Jul-31  20:44    180270    80,5     25,2
Callisto    2017-Jan-25  00:25    285824    67,2     21
Io          2017-Jun-07  00:10    217693    66,7     20,8
Io          2017-Apr-13  03:49    245136    59,2     18,5
Ganymede    2016-Nov-20  19:02    372453    56,5     17,7
Europa      2017-Jul-20  18:37    224189    56,0     17,5
Europa      2017-Apr-01  21:46    230908    54,4     17
Ganymede    2016-Oct-30  02:09    400230    52,6     16,4
Io          2017-Feb-17  07:16    279940    51,9     16,2
Ganymede    2017-Sep-02  11:54    410075    51,3     16
Europa      2017-Mar-22  01:44    266977    47,0     14,7

I wonder if resolution of JIRAM's images will be better or worse than that of MVIC images during NH Jupiter flyby 2 years ago?

[volcanopele]

I thought JIRAM had a smaller IFOV than JunoCAM, 250 microradians versus ~800? Therefore, wouldn't the spatial resolution of JIRAM be better than JunoCAM's?

[tedstryk]

Those are not km/pixel numbers, they are the moons' maximum size in pixels

[dmuller]

for those close-approach tables, you really need spice kernel files, but I believe that JPL Horizons also has this capability, but I haven't given a try.

Well the Horizons webpage states the following, so get your resuts emailed to you for close approaches:

NOTE: Although the web-interface to HORIZONS provides nearly all capabilities of the primary telnet interface (and email interface), it does not provide the following:
Small-body PARAMETER-MATCHING population searches
(use the small-body search engine as an alternative)
Integration of USER-INPUT ORBITS
SPK BINARY FILE production
CLOSE-APPROACH TABLES

[volcanopele]

Those are not km/pixel numbers, they are the moons' maximum size in pixels

Thanks for the correction there, thanks. I see it now.

[dmuller]

A generic question about trajectories: does anybody in here know how to work the NAIF Spice Kernel tools/files (or whatever it's called ...) I think they would provide more accurate information for my realtime simulations than Horizons, but I just cant understand on how to work them. All I'd need is something to convert the SPK files into the good old 4 dimensions (x,z,y [wrt to solar system barycenter] and time). Feel free to send me a private message as well.

Thanks for your help in advance!

[mcaplinger]

does anybody in here know how to work the NAIF Spice Kernel tools/files (or whatever it's called ...) I think they would provide more accurate information for my realtime simulations than Horizons...

http://naif.jpl.nasa.gov/naif/toolkit.html but you will have to write code to use it. There's no reason that Horizons isn't just as accurate as it's probably just using the SPICE kernels internally anyway. And the orbit is going to be different than any available kernel anyway, based on the launch date and injection errors, TCMs, etc.

[dmuller]

Thanks for your reply! I have the toolkit ...

but you will have to write code to use it.

... which is the problem. I wasnt actually looking at it for Juno, but for some other missions and events (especially C/A) where Horizons is not up-to-date or as accurate as I'd like it to be. So if anybody has some ready-made SPK to (x,y,z,t) converter (the kind of one-click-and-it's-done) then I'd love a copy of it :-)

EDIT 26-Jan Thanks to a very kind soul who provided a very easy solution (easy = I can handle it!) I can now load SPICE kernels into the realtime simulations, greatly enhancing the accuracy of the trajectory of some missions. First update applied to Dawn. Go Celestia!

[tedstryk]

Something else came to mind with regard to Io...would JunoCam be able to do anything equivalent to a CPROTO oversampling to slightly improve resolution?