[X] My Assistant

[jasedm]

Information on the current rev has been posted on the Ciclops 'looking ahead' page. This includes the Titan targeted encounter (pretty well- detailed observational timeline here), and a Voyager-class flyby of Janus, with ISS observations at around 160,000km. This won't be the closest remaining pass of Janus (I think the last few weeks of the prime mission have two closer passes) but it should reveal some previously unseen territory towards the south pole (or unseen at a reasonable distance anyhow)

[Holder of the Tw...]

Here is a link -

Rev 59

[CAP-Team]

Hmm they use Celestia to generate their images. is the Janus model and map somewhere to download?

[Phil Stooke]

Here!

http://publish.uwo.ca/~pjstooke/plancart.htm

My stuff is all over the place. I'm not sure where they picked it up, but I'm the ultimate source. The shape model might be a new version by Peter Thomas.

Phil

[volcanopele]

Yeah the images we use for the Looking Ahead page mostly come from Celestia. The Janus model is the default model that comes with Celestia, which I assume is Phil's. Peter hasn't published his shape model for Janus yet.

[claurel]

Yeah the images we use for the Looking Ahead page mostly come from Celestia. The Janus model is the default model that comes with Celestia, which I assume is Phil's. Peter hasn't published his shape model for Janus yet.

If there are any better versions of shape models for Saturnian moons available than the ones currently in Celestia, I'd love to hear about them. I've seen some images indicating that people have make some 3D reconstructions, but I haven't seen any models published that are based on Cassini date.

--Chris

[peter59]

I have one question about Janus.

Planetary.org Site: Janus (S/1980 S1)
The closest flyby will be on June 30, 2008 (rev 74) at about 44,636 kilometers (26,782 miles).

Cassini-Huygens site (Janus).
No targeted flyby. Closest approach: June 1, 2008 -- 14,363 kilometers (8,925 miles)

Where is Truth ?

[jasedm]

I was wondering this too. There are now some (small) discrepancies in the information concerning moon flyby distances in the final weeks of the prime tour - Cassini's orbital tour has been tweaked quite a bit with trim manoevres since information was first published.
From various sources, these are distances that I have seen quoted for the Janus flyby on June 1st 2008:

14,363 - NASA Cassini-Huygens moons page
32,786
13,691
23,000 - NASA Cassini-Huygens encounters page

And these for the 30th June 2008 pass:

44,731
69,000
66,151 - NASA Cassini-Huygens encounters page
*EDIT*
29,812 - list posted by John S in the extended mission thread on this forum

Obviously, the trajectory after 30th June 2008 was completely unknown before orbit insertion, as it was not certain whether there would be a mission extension.

[elakdawalla]

Ah, that planetary.org page is outdated -- I'd totally forgotten about those encounter lists when I updated the tour page. I have some serious work to do updating the Saturn icy satellite pages.

My new tour page does not include future encounters with "rocks" because (a) there's a ton of them and ( imaging is not often performed. So for rocks I'm now waiting until images hit the PDS, then I add in whatever encounters there was imaging done after the fact.

Here's the latest information I received from Dave Seal on all Janus encounters during the prime and extended missions. All are nontargeted. June 30 2008 is still the closest one.

00JA (nt) 2004-183T01:51 Jul-01 Inbound 67678 km flyby, speed = 12.8 km/s, phase = 106°
55JA (nt) 2008-003T22:11 Jan-03 Inbound 118244 km flyby, speed = 10.1 km/s, phase = 154°
59JA (nt) 2008-051T19:08 Feb-20 Inbound 110073 km flyby, speed = 17.3 km/s, phase = 111°
63JA (nt) 2008-092T19:09 Apr-01 Inbound 117048 km flyby, speed = 16.6 km/s, phase = 148°
67JA (nt) 2008-131T00:06 May-10 Inbound 120801 km flyby, speed = 16.3 km/s, phase = 156°
69JA (nt) 2008-146T22:50 May-25 Inbound 63900 km flyby, speed = 20.4 km/s, phase = 134°
70JA (nt) 2008-153T22:13 Jun-01 Inbound 32584 km flyby, speed = 22.1 km/s, phase = 109°
74JA (nt) 2008-182T08:57 Jun-30 Inbound 30983 km flyby, speed = 22.6 km/s, phase = 123°
75JA (nt) 2008-189T08:57 Jul-07 Inbound 80944 km flyby, speed = 22.6 km/s, phase = 94°
83JA (nt) 2008-246T23:28 Sep-02 Inbound 86894 km flyby, speed = 19.4 km/s, phase = 156°
88JA (nt) 2008-283T18:56 Oct-09 Inbound 89447 km flyby, speed = 19.4 km/s, phase = 150°
90JA (nt) 2008-298T09:14 Oct-24 Inbound 108161 km flyby, speed = 19.5 km/s, phase = 132°
115JA (nt) 2009-207T17:06 Jul-26 Outbound 94006 km flyby, speed = 9.9 km/s, phase = 59°
126JA (nt) 2010-044T16:22 Feb-13 Inbound 114968 km flyby, speed = 14.4 km/s, phase = 29°
129JA (nt) 2010-097T13:44 Apr-07 Outbound 74669 km flyby, speed = 2.8 km/s, phase = 39°

--Emily

[edstrick]

I've long thought that a good "figure of merit" for an encounter with a moon or a "rock" is the peak number of illuminated pixels during the encounter. An adjusted figure of merit might be that value with any "imaging excluded" times excluded, for example times with slew-rates too high for imaging.

[jasedm]

Here's the latest information I received from Dave Seal on all Janus encounters during the prime and extended missions. All are nontargeted. June 30 2008 is still the closest one.

--Emily

And the 30th June flyby is I believe the only one of the two passes remaining in the prime mission which was/is definitely included in spacecraft sequences for ISS attention (although not necessarily at closest approach) unless this part of the sequence was changed following XM approval.

[tallbear]

And the 30th June flyby is I believe the only one of the two passes remaining in the prime mission which was/is definitely included in spacecraft sequences for ISS attention (although not necessarily at closest approach) unless this part of the sequence was changed following XM approval.

some comments on questions raised and the other info in this thread ....

The "TOUR" has been changed a number of times since SOI ... each change of the Tour alters non-targeted flybys
downstream ..... you need a 'scorecard' to track this info <G>.... meanwhile, info on websites tends to be static
and/or slow to change.

As for the table of Janus flybys from Dave ( an accurate source of current info ) ..... keep in mind that the phase angle
at closes approach is not too meaningful as an indicator of the flyby's 'usefullness' .... 30 min before or after C/A the
phase angle can be substantially different

.... As for the Jun 30 2008 flyby, the phase angle drops to ~ 90 deg about 30 min after C/A ... BUT .... JANUS goes inot
eclipse just minutes after C/A....

T

[jasedm]

Thanks Tallbear for the information.
There appear to still be gremlins on the Cassini Huygens raw images page, so the Janus images still aren't up yet...(nor anything in the last two weeks - you Titan afficionados must be grinding your teeth by now following the last flyby)

[ugordan]

Well, there are a few OPNAVs that appeared on the raw page yesterday so... eppur si muove...

[jasedm]

... eppur si muove...

Said 'sotto voce' no doubt