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TiME
jasedm
post May 8 2011, 10:33 AM
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QUOTE (Juramike @ May 8 2011, 02:40 AM) *
the two CH3 groups would be gauche to each other (hindered rotation), negating any hyperconjugation and thus increased polarization of the molecular orbitals.


Just what I was going to say Mike...... wink.gif

Very exciting news about the proposal.

Re: pictures of the lake surface, artists renderings I've seen show what looks like a light source - enough perhaps with the available power to be able to get some some good images within a metre or two of the craft?
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machi
post May 8 2011, 01:23 PM
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It looks (from scheme), that two imaging instruments are planned. One is down-looking (descent imager?) and on side-looking (panoramic camera?).
I would like to ask two questions. It's possible use descent camera to look at the bottom of the mare (if it's not too deep, liquid is transparent and probe has source of light) and I don't fully understand why is Ligeia mare primary target. It looks, that Kraken mare (secondary target) is better suited from communication point of view and is more suitable for possible mission extension.


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centsworth_II
post May 8 2011, 01:54 PM
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Unfortunately it does look a bit iffy for getting good descent images of the shoreline. Just for fun, I superimposed pre-Huygens landing descent image footprint projections over a map of Ligeia Mare. Haze would probably prevent good imaging outside of the green octagon, which barely touches the shore. The really good wide Huygens panorama was within the magenta circle, and the great landing area panorama would just cover the black X. I'm hoping for some improvements over the Huygens "camera". Maybe a telescopic lens?

The probe being blown to shore during the course of the mission doesn't look too good either. The probe could easily land 100 km from the shore and even a "perfect" wind, blowing constantly in one direction toward the nearest shoreline would need to blow the probe over a kilometer a day for three months. Not a likely scenario.

Attached Image

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ugordan
post May 8 2011, 02:20 PM
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QUOTE (centsworth_II @ May 8 2011, 03:54 PM) *
I'm hoping for some improvements over the Huygens "camera". Maybe a telescopic lens?

You don't want a telescopic lens. It's not the angular resolution that's the problem, it's the haze extinction. You want a really good S/N ratio to combat the reduction in contrast when looking through an optically thick layer of haze. Huygens DISR was already pretty good in this respect. IIRC it returned 10 bit data to Earth, square-root-encoded from 14 bit A/D output. 10 bit data is still pretty much standard for spacecraft today.

Where there could be some improvement over Huygens is in selecting a narrow spectral window like ISS CB3 instead of a broader range Huygens used. This does come at a price though - much longer exposures needed and if your spacecraft is rocking really hard on the way down this virtually guarantees image smear.


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rlorenz
post May 8 2011, 03:00 PM
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QUOTE (ugordan @ May 8 2011, 10:20 AM) *
Where there could be some improvement over Huygens is in selecting a narrow spectral window like ISS CB3 instead of a broader range Huygens used. This does come at a price though - much longer exposures needed and if your spacecraft is rocking really hard on the way down this virtually guarantees image smear.


I'd love to enter the discussion, but the Step 1 selection just means this is now a much more
cut-throat competition, and many details of the mission will have to remain proprietary for now.
There are very smart people on the team (a look at author lists of abstracts will clue you in)
who spent a lot of time thinking how best to do imaging, and there are very good reasons
for choosing Ligeia, etc.

It is my intent to make as many details public as is feasible, to engage the scientific community
and the public at large to the greatest extent, but the competitive process will restrict that
for the time being.

Hopefully one day I'll get to write the full story in a book - the followup to Titan Unveiled. I'm thinking
a good title might be 'A Brief History of TiME'......
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brellis
post May 8 2011, 03:25 PM
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QUOTE (nprev @ May 8 2011, 01:44 AM) *
I'll get my hat.


Thanks for the laugh! laugh.gif
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Greg Hullender
post May 8 2011, 05:10 PM
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QUOTE (rlorenz @ May 8 2011, 08:00 AM) *
a good title might be 'A Brief History of TiME'......


Bravo!

I certainly hope to see this one fly.

--Greg :-)
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centsworth_II
post May 8 2011, 05:33 PM
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QUOTE (ugordan @ May 8 2011, 09:20 AM) *
You don't want a telescopic lens. It's not the angular resolution that's the problem, it's the haze extinction....
I was thinking about a telescopic lens to image the shoreline from a hundred plus km away at an altitude of under thirty km where, hopefully, haze will not be much of an issue. It may be too much risk to design a lens around the assumption of clear skies under thirty km though.

What a problem! Designing a descent imaging system while taking volatile weather into account!
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ugordan
post May 8 2011, 05:53 PM
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I was under the impression the haze doesn't "end" below a certain altitude, it just becomes transparent enough. It's not that thick per km to start with (not what you'd think of fog on Earth). Loking a hundred km into the distance horizontally likely wouldn't be any different than looking vertically. A narrow-angle imager would also be much more sensitive to atmospheric buffeting.


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eoincampbell
post May 8 2011, 06:57 PM
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QUOTE (rlorenz @ May 8 2011, 07:00 AM) *
Hopefully one day I'll get to write the full story...


And hopefully we'll all get to read it!
Very best of luck to you and your esteemed colleagues, rlorenz, on this amazing adventure !


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nprev
post May 8 2011, 09:13 PM
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Ralph, although I'm sure it's proprietary right now, I'll be fascinated to see the EDL methodology.


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A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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ElkGroveDan
post May 8 2011, 09:34 PM
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All in due...... well, you know.


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If Occam had heard my theory, things would be very different now.
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nprev
post May 8 2011, 09:55 PM
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<groan>...walked right into that one! tongue.gif


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Explorer1
post May 8 2011, 11:39 PM
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With luck, there should be a naming contest or we'll have a full decade of puns to look forward too.
Or we can just avoid making clever acronyms (like MESSENGER) in the first place and give the mission a normal name from the start, like New Horizons.

Alan Stern put it best way back when:

http://pluto.jhuapl.edu/overview/piPerspec...ctive_05_2005_1
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nprev
post May 9 2011, 12:31 AM
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Not a bad point, Explorer, and I think that NH was very well-named indeed.

Too bad that so many of the maritime pioneer names have been taken; TiME, of all missions to date, deserves a nautical name. Frankly, though, I don't care if we call it the "Benthic Explorer: Nautical Depth, Environmental Reconnaissance" or "Nautical Probe: Revealing Ethane Vastness" ; I just want it to fly, very, very badly.

(Okay...so maybe I would slightly favor the latter acronym...smile.gif)


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