Cassini EOL

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John Van Vliet
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Cassini EOL

Post #1by John Van Vliet » 12.09.2017, 02:40

on the 15'th in 4 days the Cassini mission comes to an end

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Added after 57 seconds:
cont.

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FarGetaNik M
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Post #2by FarGetaNik » 12.09.2017, 08:31

Here's my take on Cassini's final moment:

goodby Cassini.jpg


Cassini is already below the surface, giving the atmosphere a more smooth appearance. It seems I am using different orbital data, since Cassini's point of impact seems to be closer to the equator compared to your screenshots.

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selden
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Post #3by selden » 12.09.2017, 11:13

FarGetaNik,

What are you using to define Cassini's orbit?

I suspect John is using the official NASA SPICE kernels, which are likely to be as accurate as possible.
Selden

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FarGetaNik M
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Post #4by FarGetaNik » 12.09.2017, 12:13

selden wrote:What are you using to define Cassini's orbit?

I suspect John is using the official NASA SPICE kernels, which are likely to be as accurate as possible.

Acually, I'm not too sure about that. I was in contact with Austin, who I cooperated with updating Juno's orbit and later he went on to do Cassini. I use his orbital data (which is on the motherlode also), but of course I can't know for sure his source... but as far as I know he used the HORIZONS system, not raw spice files that tend to be updated more frequently.

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Post #5by John Van Vliet » 12.09.2017, 20:16

the cassini spice kernels on the naif ftp server are a bit OLD.
So i am using the Horizons kernels ,and the most recent kernel is "170911BP_SCPSE_17224_17258.bsp"
from the "BP" this is the second update to the predictive kernel
and was created on 9-11-2017 hence the ( 17 09 11 ) in the name

Code: Select all


BRIEF -- Version 4.0.0, September 8, 2010 -- Toolkit Version N0066
 
 
Summary for: 170911BP_SCPSE_17224_17258.bsp
 
Bodies: CASSINI (-82)           SUN (10)                IAPETUS (608)
        MERCURY BARYCENTER (1)  MOON (301)              PHOEBE (609)
        VENUS BARYCENTER (2)    EARTH (399)             JANUS (610)
        EARTH BARYCENTER (3)    MIMAS (601)             EPIMETHEUS (611)
        MARS BARYCENTER (4)     ENCELADUS (602)         HELENE (612)
        JUPITER BARYCENTER (5)  TETHYS (603)            ATLAS (615)
        SATURN BARYCENTER (6)   DIONE (604)             PROMETHEUS (616)
        URANUS BARYCENTER (7)   RHEA (605)              PANDORA (617)
        NEPTUNE BARYCENTER (8)  TITAN (606)             SATURN (699)
        PLUTO BARYCENTER (9)    HYPERION (607)
        Start of Interval (ET)              End of Interval (ET)
        -----------------------------       -----------------------------
        2017 AUG 12 04:00:06.000            2017 SEP 15 15:59:54.000
 

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Diigg M
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Post #6by Diigg » 13.09.2017, 08:57

John, a novice doubt.
How do you make it show only part of the orbit?
If I activate the option to show orbits, it shows me all the complete orbits.

Cassini-Saturn.jpg

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FarGetaNik M
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Post #7by FarGetaNik » 13.09.2017, 12:24

Diigg, I assume you are using a sampled orbit (xyz or xyzv files). This orbit type shows all data at once. You would have to cut the file in different parts to only show the segments you want, or use spice orbit definition with fitting settings to show only one loop at a time.


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