Juno perijoves 2 and 3, October 19 and December 11, 2016 Options

[scalbers]

Gerald - here is the correction term for the orbital acceleration as it appears in my vintage (1970s) software. I'm unsure how easy it would be to retool this to run for Jupiter, though we could at least do some type of scale analysis on this, or augment another simulation program accordingly. The RDRD or r dot rdot term is sensitive to how elliptical the orbit is as one might expect.

! ADD PERTURBATIVE ACCELERATION DUE TO GENERAL RELATIVITY
RDRD=X(I)*XD(I)+Y(I)*YD(I)+Z(I)*ZD(I)
VSQ=XD(I)*XD(I)+YD(I)*YD(I)+ZD(I)*ZD(I)
A=FOURM*RLCM1-VSQ*CM2
B=FOURM*RDRD*RLCM3
XDD(I)=XDD(I)*(1.D0-A)+B*XD(I)
YDD(I)=YDD(I)*(1.D0-A)+B*YD(I)
ZDD(I)=ZDD(I)*(1.D0-A)+B*ZD(I)

The terms are defined as follows:

RDRD - r dot rdot - dot product of position and velocity
XYZ - position vector in AU
XD,YD,ZD - velocity vector
XDD,YDD,ZDD - acceleration vector
FOURM - 4 times the mass of the central object
RLCM1 - inverse distance between the two bodies
CM2 - 1 / c squared (c = speed of light)

I should try and look up the Cowell Astronomical Papers reference where I obtained this. The above just applies to calculating the GR perturbed positions. The clock changes are a different calculation.

[Gerald]

This is an animated gif of preliminarily processed PJ3 approach images:

The last 10 or so frames have been too large to be properly aligned by centering.

Here the stills, and a respective version showing more context.

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S.C.Albers:
I guess, 'I' is an index in a loop (iteration?). Not quite sure about the meaning of '1.D0', I guess simply 1.0 in some progamming language. Besides this, it looks fairly easy to implement. Thanks!
Transforming SPICE trajectories to this algorithm should be well-feasible, too, with position vectors relative to Jupiter.

[mcaplinger]

Not quite sure about the meaning of '1.D0'

Double-precision floating-point constant.
Once upon a time there was a language called FORTRAN and all serious scientific programming was done in it...
similar syntax is used in languages like IDL.

[Gerald]

I see. Then the 'I' is likely used as an array index to overcome the lack of function scopes for (local) variables.
Not needed anymore in modern computer languages.

[eliBonora]

Here a couple of PJ3 processing and a test anaglyph

[Gerald]

Here a synopis of the PJ03 Approach Movie images:

This version is reduced in size, brightness-stretched in a linear way, and saturation-enhanced.
I've submitted a less processed, larger version, to the missionjuno site to allow others post-processing according to their own requirements.

[mcaplinger]

BTW, if people don't know about the work of John Rogers of the British Astronomical Association's Jupiter section, you can find it at https://www.britastro.org/node/7982 (some also posted on missionjuno but I prefer to go straight to the source.)

Refreshing change from all this processing discussion!

[fredk]

Once upon a time there was a language called FORTRAN and all serious scientific programming was done in it...

That's one dinosaur that still walks this earth, at least in cosmology and GR work. Gained a few lovely feathers over the years...

[scalbers]

Also still used quite a bit in numerical weather prediction. It's more modernized now in various respects - though even if it changes it's still called FORTRAN. So it carries on beyond the age of the dinosaurs, kind of like birds...

For Gerald - indeed FORTRAN can be pretty readily translated into IDL. The "I" index is representing one time step as part of a time series. We'd also have to check that the physical units of mass are consistent with however distance and time units are being specified. Maybe pure SI units would work OK.

[Gerald]

BTW, if people don't know about the work of John Rogers of the British Astronomical Association's Jupiter section, ...

John Rogers just published the PDF version of the (first) PJ03 report.
The PJ03 images will undergo further analysis over the next weeks.

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S.C.Albers: Thanks for resolving the remaining question.
Yes, since FORTRAN-77, there have been further extensions in FORTRAN-90. There exists such a large number of programming languages, that at some point I discontinued attempts to track all those trends and paradigm changes. Eventually it's hard to infer the language from a small excerpt of source code. The same sequence of characters can be interpreted entirely different in the context of different languages, sometimes even within the same language. This includes own "proprietary" languages or language extensions... That's endless... Even "IDL" is overloaded (Interactive Data Language vs. Interface Definition Language). But I know, which IDL is meant in this context.

[Gerald]

PJ03 departure movie, RGB images, decompanded, linearly brightess-stretched by factor 2, square-root encoded, reduced to 15 pixels per (cylindrical) camera degree:

[Gerald]

PJ03 Departure and Marble Movie, browsable RGB images #131 to #588, 30 pixels per camera degree (images in overview are 5x reduced, and hyperlinks to 30 pixels version).

[Gerald]

Methane band PJ03 Departure Movie images (reduced, jpg):


The browsable 30 pixels/cylindrical camera degree versions of the methane images of the PJ03 Departure and Marble Movie sequence.

[Gerald]

... And an example of a false-color image using the CH4 channel for brightness, and RGB for hue / saturation:

Saturation is enhanced.

[Gerald]

One of four slightly different preliminary PJ03 animations I've provided on youtube.
They cover approach, close-up, departure and marble movie phase.