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Titan Review article
rlorenz
post Dec 14 2007, 05:02 PM
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This just out. Not earth-shattering, but colorful - maybe handy as an up-to-date
Titan intro

http://www.jhuapl.edu/techdigest/td2702/lorenz.pdf
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Webscientist
post Dec 16 2007, 08:12 PM
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I bought in 2004 "Lifting Titan's Veil".It's of course the reference for Titan and I will reread it very soon to compare with what we know now ( presented in Titan revealed).

I'm fascinated by the radar images of the lakes in your Titan review.Unfortunately, the radar images don't give any indication on the appearance of the liquid.Does it appear dark, orange, blue... from a human eye?

Some dark and uniform patches located on the "white snow" of Iapetus made me think they were pools of hydrocarbons, similar to what we might find on Titan. Do you think that the idea is relevant?
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rlorenz
post Dec 17 2007, 01:37 PM
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QUOTE (Webscientist @ Dec 16 2007, 03:12 PM) *
I'm fascinated by the radar images of the lakes in your Titan review.Unfortunately, the radar images don't give any indication on the appearance of the liquid.Does it appear dark, orange, blue... from a human eye?

Some dark and uniform patches located on the "white snow" of Iapetus made me think they were pools of hydrocarbons, similar to what we might find on Titan. Do you think that the idea is relevant?


Lakes - get asked this a lot. Dunno. Probably like one of those 'Random_City at night' postcards - black.
Since the lakes are at the poles, its often nighttime. Sun and saturnshine is always low on the horizon, never
high in the sky, and only red light filters down to the ground. If you brought your own white light with you,
depends. Pure methane would look blueish - like Neptune - because of the methane absorptions in red. But
if there is a lot of reddish tholin suspended in it, maybe brownish (wine-dark sea?). So mostly black

White snow - even stuff like benzene (for example) at liquid nitrogen temperatures is white. I think
maybe anthracene is yellow (maybe Juramike can explain how things get dark/colored?). Soot of course is
black. I don't think we can rule out any of these of Titan (or Iapetus, for that matter..)
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vjkane
post Dec 17 2007, 04:53 PM
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QUOTE (rlorenz @ Dec 17 2007, 01:37 PM) *
Pure methane would look blueish - like Neptune - because of the methane absorptions in red. But
if there is a lot of reddish tholin suspended in it, maybe brownish (wine-dark sea?).


Ralph -

In all the discussions of Titan missions, has anyone discussed putting a "lander" in the one of the lakes to study their composition?

All -

At the AGU conference, there was a poster proposing that the "land" area around the lakes might be a lot like the karst regions of Earth where the liquid has eroded the surface into dramatic shapes. It would be beautiful to see, but I can't imagine an engineering team ever agreeing that such an area would be safe to land in. ("What part of cliffs and unsafe don't you understand?...)


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Mongo
post Dec 17 2007, 06:46 PM
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QUOTE (vjkane @ Dec 17 2007, 04:53 PM) *
In all the discussions of Titan missions, has anyone discussed putting a "lander" in the one of the lakes to study their composition?


I would love a "Pioneer Venus" style mission with at least five Huygens-style landers plus an orbiter, with each lander directly sampling one of the major terrain units:

1) the bright terrain as seen at Xanadu
2) the dark brown equatorial dune fields
3) the dark blue channel deposits
4) the very bright, possibly volcanism-related deposits as seen north of Hotei Arcus
5) the north-polar liquid hydrocarbon "oceans" (or Ontario Lacus, depending on approach geometry)

If there were room in the budget for a balloon in addition to this, it would be great, but I have a feeling that even these five landers would be a budget-buster.

Bill
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rlorenz
post Dec 18 2007, 12:22 AM
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(we identified the same 5 terrain types as possible targets, btw)
Problem with this concept are (1) that this would mean having 5 sets of expensive chemical analysis
payloads (2) that in a battery-limited lifetime of a few hours (remember you need to stay warm
as well as functioning) it is difficult to be sure that you will acquire the surface sample you want
(3) Huygens-style landing might not be viable on cryovolcanic terrain, or Xanadu
(4) short-duration landers do not get long-term science like meteorology, seismology, magnetometry,
changing illumination, rotation state determination


QUOTE (Mongo @ Dec 17 2007, 01:46 PM) *
I would love a "Pioneer Venus" style mission with at least five Huygens-style landers plus an orbiter, with each lander directly sampling one of the major terrain units:

1) the bright terrain as seen at Xanadu
2) the dark brown equatorial dune fields
3) the dark blue channel deposits
4) the very bright, possibly volcanism-related deposits as seen north of Hotei Arcus
5) the north-polar liquid hydrocarbon "oceans" (or Ontario Lacus, depending on approach geometry)

If there were room in the budget for a balloon in addition to this, it would be great, but I have a feeling that even these five landers would be a budget-buster.

Bill
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Mongo
post Dec 18 2007, 12:58 AM
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QUOTE (rlorenz @ Dec 18 2007, 12:22 AM) *
(we identified the same 5 terrain types as possible targets, btw)
Problem with this concept are (1) that this would mean having 5 sets of expensive chemical analysis
payloads (2) that in a battery-limited lifetime of a few hours (remember you need to stay warm
as well as functioning) it is difficult to be sure that you will acquire the surface sample you want
(3) Huygens-style landing might not be viable on cryovolcanic terrain, or Xanadu
(4) short-duration landers do not get long-term science like meteorology, seismology, magnetometry,
changing illumination, rotation state determination


It sounds like the biggest problem would be the short lifetime of a battery-powered lander, combined with the limited power available and the lack of choice about where the lander touches the surface. Not to mention that the probe would be duplicated four or five times, and the same mass budget could presumably send a much more capable single payload.

The other option would be some form of dirigible balloon, with ducted fan(?) for some degree of directional control, that mainly stays in the troposphere with occasional descents to the surface for samples. It would have to be powered by RTGs or perhaps a nuclear reactor, which should also allow enough power for a direct link to Earth, eliminating one link in the communication chain (although the bit rate may be higher if an orbiter can relay its transmissions).

The orbiter would have to be the highest priority in my opinion, as it would provide at a reasonable cost considerably better radar and optical coverage than Cassini, as well as a possible telecom capability if there is budgetary room for a surface probe. Most of the (very valid) objections to the Huygens-style landers suggest that any surface/atmospheric probe must be nuclear-powered, as well as having airborn capability -- and indeed would spend almost all its Titan time well above the surface. This is discussed in far more detail in the OPAG reports.

The combination of orbiter and dirigible balloon would be very expensive, though. This is one time that a collaboration with ESA and perhaps other space agencies would be helpful (if ITAR allows it). The additional administrative workload would be difficult, but I think that the increased mission capability would be worth it. Of course I am not the one who would have to shoulder the extra workload.

Bill
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rlorenz
post Dec 18 2007, 01:59 PM
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QUOTE (Mongo @ Dec 17 2007, 07:58 PM) *
.....
The other option would be some form of dirigible balloon, with ducted fan(?) for some degree of directional control, that mainly stays in the troposphere with occasional descents to the surface for samples. It would have to be powered by RTGs or perhaps a nuclear reactor
.......


OK. right there you took the thread away from discussing the next Flagship into 'someday, wouldnt it be
nice'

You can debate the readiness of an RTG dirigible, but reactors are not presently on the cards.

btw - ITAR doesnt *prevent* anything, it just necessitates paperwork. Clean interfaces help.
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dvandorn
post Dec 18 2007, 06:31 PM
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QUOTE (rlorenz @ Dec 18 2007, 07:59 AM) *
You can debate the readiness of an RTG dirigible, but reactors are not presently on the cards.

And remember, folks, this comes from someone who was a lot closer to the JIMO debacle than most of us.

-the other Doug


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“The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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rlorenz
post Dec 18 2007, 08:16 PM
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QUOTE (dvandorn @ Dec 18 2007, 01:31 PM) *
And remember, folks, this comes from someone who was a lot closer to the JIMO debacle than most of us.


Actually I stayed well clear of that one (thankfully). I was, however, on the NRC panel that
contemplated it and other such missions

http://www.nap.edu/catalog.php?record_id=11432
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dvandorn
post Dec 18 2007, 08:42 PM
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QUOTE (rlorenz @ Dec 18 2007, 02:16 PM) *
Actually I stayed well clear of that one (JIMO) (thankfully). I was, however, on the NRC panel that
contemplated it and other such missions.

That still makes you closer and more knowledgeable than most (if not all) of the rest of us about the specific issue of flying full-scale nuclear reactors on outer planet probes, Ralph.

Sure, it's possible. The technical challenges and risks are just a little higher than can be overcome at the moment, I think.

-the other Doug


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“The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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Posts in this topic
- rlorenz   Titan Review article   Dec 14 2007, 05:02 PM
- - ugordan   QUOTE "Figure 1. A false-color composite of C...   Dec 14 2007, 05:13 PM
- - volcanopele   Well, I guess the secret is out. The ISS camera i...   Dec 14 2007, 05:42 PM
- - djellison   I assume the D is for Danger? Doug   Dec 14 2007, 06:02 PM
- - remcook   Yeah that Space Station also makes its appearance ...   Dec 14 2007, 06:07 PM
- - rlorenz   Hmm. So nice of you all to speak in such glowing t...   Dec 16 2007, 03:57 PM
|- - ngunn   Great article, thanks for sharing it here. In advo...   Dec 17 2007, 10:06 AM
|- - rlorenz   QUOTE (ngunn @ Dec 17 2007, 05:06 AM) Gre...   Dec 17 2007, 01:43 PM
|- - ngunn   QUOTE (rlorenz @ Dec 17 2007, 01:43 PM) ...   Dec 17 2007, 03:19 PM
|- - dburt   QUOTE (ngunn @ Dec 17 2007, 08:19 AM) How...   Dec 17 2007, 08:04 PM
- - djellison   Hand on heart - I've been keeping it ready for...   Dec 16 2007, 04:29 PM
- - Mongo   You know that we're just teasing. I personall...   Dec 16 2007, 04:30 PM
- - Floyd   Ralph, I really enjoyed the article--keep up the e...   Dec 16 2007, 05:21 PM
- - nprev   Great article, Ralph; certainly a call to arms for...   Dec 16 2007, 06:45 PM
- - Rob Pinnegar   Nice article. I picked up a few things from it tha...   Dec 16 2007, 06:54 PM
- - Webscientist   I bought in 2004 "Lifting Titan's Veil...   Dec 16 2007, 08:12 PM
|- - rlorenz   QUOTE (Webscientist @ Dec 16 2007, 03:12 ...   Dec 17 2007, 01:37 PM
|- - vjkane   QUOTE (rlorenz @ Dec 17 2007, 01:37 PM) P...   Dec 17 2007, 04:53 PM
||- - Mongo   QUOTE (vjkane @ Dec 17 2007, 04:53 PM) In...   Dec 17 2007, 06:46 PM
|||- - rlorenz   (we identified the same 5 terrain types as possibl...   Dec 18 2007, 12:22 AM
|||- - Mongo   QUOTE (rlorenz @ Dec 18 2007, 12:22 AM) (...   Dec 18 2007, 12:58 AM
|||- - rlorenz   QUOTE (Mongo @ Dec 17 2007, 07:58 PM) ......   Dec 18 2007, 01:59 PM
||||- - dvandorn   QUOTE (rlorenz @ Dec 18 2007, 07:59 AM) Y...   Dec 18 2007, 06:31 PM
|||||- - rlorenz   QUOTE (dvandorn @ Dec 18 2007, 01:31 PM) ...   Dec 18 2007, 08:16 PM
|||||- - dvandorn   QUOTE (rlorenz @ Dec 18 2007, 02:16 PM) A...   Dec 18 2007, 08:42 PM
||||- - NMRguy   QUOTE (rlorenz @ Dec 18 2007, 02:59 PM) O...   Dec 19 2007, 01:14 PM
||||- - rlorenz   QUOTE (NMRguy @ Dec 19 2007, 08:14 AM) So...   Dec 19 2007, 02:35 PM
||||- - ngunn   QUOTE (rlorenz @ Dec 19 2007, 02:35 PM) A...   Dec 19 2007, 02:57 PM
||||- - JRehling   A purely equatorial orbit would preclude RADAR obe...   Dec 19 2007, 10:24 PM
|||- - vjkane   QUOTE (Mongo @ Dec 18 2007, 12:58 AM) The...   Dec 18 2007, 05:05 PM
|||- - Mongo   QUOTE (vjkane @ Dec 18 2007, 05:05 PM) So...   Dec 18 2007, 05:55 PM
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||||- - rlorenz   QUOTE (Mongo @ Dec 18 2007, 12:55 PM) So ...   Dec 18 2007, 08:13 PM
||||- - Mongo   QUOTE (rlorenz @ Dec 18 2007, 08:13 PM) Y...   Dec 18 2007, 08:59 PM
||||- - ngunn   QUOTE (rlorenz @ Dec 18 2007, 08:13 PM) Y...   Dec 18 2007, 10:24 PM
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|- - rlorenz   QUOTE (Juramike @ Dec 17 2007, 03:34 PM) ...   Dec 18 2007, 12:24 AM
|- - Juramike   QUOTE (rlorenz @ Dec 17 2007, 07:24 PM) ....   Dec 18 2007, 04:26 AM
- - JRehling   Great synopsis. The points regarding the diversity...   Dec 16 2007, 11:08 PM
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- - scalbers   Or could we suggest elements of the Vega Venus mis...   Dec 17 2007, 07:30 PM
|- - vjkane   QUOTE (scalbers @ Dec 17 2007, 07:30 PM) ...   Dec 17 2007, 07:46 PM
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|- - ugordan   QUOTE (vjkane @ Dec 20 2007, 02:17 AM) My...   Dec 20 2007, 08:34 AM
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