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Titan boat on $450 million - how is it possible?
Mark6
post Sep 16 2009, 01:51 PM
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Today I heard this on NPR: Exploring a moon by boat
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The mission could launch around 2016 and be sailing on Titan around 2022 — if this team gets through a highly competitive selection process to get funding from NASA. Stofan and her colleagues are busy working up their proposal for when NASA begins to accept ideas for future Discovery-class missions.

Quick Google search on Dr. Stofan's name found this: What Next for Titan?
QUOTE
Ellen Stofan has a Discovery-class Titan lake lander proposal. I've not seen the presentation, but a friend who has tells me that it is less capable than the ESA lake lander proposed for TSSM. (This would make sense – ESA had a budget of ~$1B for just the lake lander and balloon. Stofan has just $450M and has to fit a carrier craft and launch vehicle into that budget.) The 2007 report did not look at lake landers. I know of Stofan by reputation, and she's highly competent. However, fitting in a carrier, lander (with entry shell), and launch vehicle within a Discovery mission budget seems ambitious. Perhaps this could be done with a New Frontiers budget ($650M with the launch vehicle provided by NASA outside this budget), although the 2007 budget suggested that a budget twice this amount would be needed just for an atmopheric probe.

Aside from above quote's understandable skepticism of the Discovery-class price tag, where would plutonium for this mission come from? I thought it is all already allocated?
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mcaplinger
post Sep 16 2009, 02:34 PM
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QUOTE (Mark6 @ Sep 16 2009, 05:51 AM) *
Aside from above quote's understandable skepticism of the Discovery-class price tag, where would plutonium for this mission come from?

From http://discoverynewfrontiers.nasa.gov/news...ews_051509.html

"Discovery Program investigations may propose the use of Advanced Stirling Radioisotope Generators (ASRGs) for missions enabled by radioisotope power systems. If selected for flight, NASA will provide up to two ASRGs, including the services associated with their provisioning on space missions, as GFE, and their costs will not be included in the cost cap."

ASRGs don't use as much Pu as thermocouple systems. NASA doesn't say where it's coming from, but presumably there is a source (I had thought that production was going to be resumed.)

As for skepticism about cost, IMHO the cost/risk pendulum has now swung to the extreme end of risk aversion and high cost, so anything that might help it swing back is a good thing.


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Mark6
post Sep 16 2009, 05:56 PM
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Does anyone know what are the competing proposals for this round of Discovery missions?
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volcanopele
post Sep 16 2009, 07:16 PM
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Another (possible) proposal is the Io Volcano Observer, which would orbit Jupiter to explore its innermost large moon, Io. Like Titan Lake Explorer, it would use ASRGs for a power source.

I've written a few posts on this proposal on my blog: http://gishbar.blogspot.com/search/label/I...cano%20Observer


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Drkskywxlt
post Sep 16 2009, 07:22 PM
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I heard this presentation by Dr. Stofan at the Satellites Panel of the Decadal Survey (I was the notetaker). There was a great deal of interest by the Panelists and other members of the audience, but some skepticism as to whether this could ever fit in a Discovery budget. The reason Dr. Stofan's team believe they might have a shot at that $450M cost cap is that for this Discovery AO, the launch vehicle and ASRGs are provided as government furnished equipment. When you subtract those two giant costs out of the equation...you get a nearly New Frontiers-level budget for a Discovery mission. The mission is targeted for one of the larger "seas" at the North Pole and the probe could have a lengthy lifespan (during an extended mission) of possibly as much as 6 months, if memory serves. The instrumentation would be limited with an imager and meteorological/physical properties suite that could do some analysis of the lake fluid and weather conditions. A descent imager and thermometer would also be part of the deal. Comms would be DTE with a slow (but sufficient) data rate.

The IVO also got several eyebrows raised and lots of questions.
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Jason W Barnes
post Sep 16 2009, 07:35 PM
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QUOTE (Drkskywxlt @ Sep 16 2009, 12:22 PM) *
The reason Dr. Stofan's team believe they might have a shot at that $450M cost cap is that for this Discovery AO, the launch vehicle and ASRGs are provided as government furnished equipment. When you subtract those two giant costs out of the equation...you get a nearly New Frontiers-level budget for a Discovery mission.


This is right. Don't see $425M and then go comparing that to previous Discovery rounds. With the launch and the ASRG's the appropriate comparison value might be something more in the vicinity of $600M.

This ain't your father's Discovery AO. It's a new ballgame.
- Jason
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stevesliva
post Sep 16 2009, 08:52 PM
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I'm skeptical that if one were to choose to send just one more lander to Titan, that a lake would be the clear place to choose to send it. Is there focus in this proposal of that specific choice? (Land vs. Mare?) It seems to me that if you could predict the weather, you'd almost want it on a solid piece of ground that will see some precipitation. That might be a pipe dream, but it sounds like the "boat" is going to be a meteorology package plus surface characterization tools. Do we have more questions about what's in a lake, or more questions about what makes any other terrain on Titan? I suppose you do learn for certain what part of the aquifer is composed of... and that answers a global question. But as for surface photos, as pointed out in later posts on the same blog, there might not be too much to see. A descent imager would be of great use, but a pancam wouldn't. If you could try to get the boat to drift to shore, though... that would be neat. Maybe give any mast more of a cross-section to the wind and less in the lake to ensure that it does drift.
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Jason W Barnes
post Sep 16 2009, 09:30 PM
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QUOTE (stevesliva @ Sep 16 2009, 01:52 PM) *
I'm skeptical that if one were to choose to send just one more lander to Titan, that a lake would be the clear place to choose to send it.


I personally agree with this statement. A lander in the dunes, for instance, might prove more interesting. But these are very focused missions, and some advantages of the lake are that it's easy to hit, the engineers won't complain that your landing site isn't flat enough, and that there is new science to be done there. Plus since the landscape will be so boring, they won't have to send as much data back to Earth and so can use a cheaper radio link wink.gif

- Jason
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Juramike
post Sep 16 2009, 09:33 PM
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Titan's terrain is pretty varied: If we did pick the land what terrain type would we sample?
The Equatorial bright stuff? the dark dune stuff? the mid-latitude RADAR-bland stuff? or the dark blue ice sand unit (Huygens part II - the taste test), or the Hotei Arcus cryovolcano stuff?

[Now if you could land on just one part of Earth, where would you send it? The white stuff at the poles, the blue stuff, the yellow-brown stuff, or the green stuff?]

Landing in a lake has the advantage of being relatively homogeneous compared to land terrain. (However, I'll contend that it is possible that the different chemical thingys could segregate out vertically into different goopy layers - sampling different depth might give different results). Another advantage of landing in a lake is that the soluble species (and some of the smaller particulates) from surrounding terrain will end up getting washed into the lakes. So in theory, tasting the lake will give you a taste of all the soluble species from all the terrain types that drain into the lake.

In ignorance of the exact instrumentation, the lake lander will have an easier time acquiring the sample, no digging or scooping, just suck through a straw and shoot into the GC (or whatever). Liquids are much easier to handle than solids. Yet other advantage is that the lake lander will drift over time. So you'll get some spatial coverage as well that a lander won't give you.

My favorite mission is still a Titan balloon that has the capability to touchdown and image and sample multiple points along it's path. Then you could hit a lake, a dune, the mid-latitude bland stuff, etc all with one mission...AND get wind and weather information at different varying locations and altitudes.





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Jason W Barnes
post Sep 16 2009, 09:43 PM
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QUOTE (Juramike @ Sep 16 2009, 02:33 PM) *
My favorite mission is still a Titan balloon that has the capability to touchdown and image and sample multiple points along it's path. Then you could hit a lake, a dune, the mid-latitude bland stuff, etc all with one mission...AND get wind and weather information at different varying locations and altitudes.


You can't hit both dunes and lakes with a balloon. You're at the mercy of the winds. And the lakes are where the giant thunderstorms are that would rip a balloon to pieces.

- Jason
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ngunn
post Sep 16 2009, 09:51 PM
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Liquid phase chemistry seems to me the biggest single target for the next Titan surface probe, and there is plenty to learn too about the physical properties and behaviour of the liquid. I do not agree that surface imagery would be boring. We could see any combination of wind waves, precipitation, fog formation, current turbulence, organic scum or other flotsam, lake bed shallows, evidence of diurnal or longer term changes in any of these, and who knows what else. All this and the ability to drift for free to new locations. To me it would be inconcievable to go there yet choose to remain either blind or immobile. So, a lake probe with a chemistry lab and camera: yes please!

EDIT: That's not to discount a balloon - I am just comparing with other possible dry landers.
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stevesliva
post Sep 16 2009, 10:51 PM
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QUOTE (Juramike @ Sep 16 2009, 04:33 PM) *
Yet other advantage is that the lake lander will drift over time.


This is compelling, but someone has to put a figure on what distance over what timescales to make it something than can honestly be considered in pitching the mission. Just seeing a shoreline would be a huge advance over never seeing one.

Many of the arguments for meteorological observations also have an important time component. I'd guess you need meteorology over at least months, especially to quash "Galileo Probe Anisotropy" arguments... what if you plop down into the lake during a supposed rainy time or foggy season, and it turns out that it doesn't fog or rain for a month? Does that just mean you missed the interesting weather? But if you can miss it, does that mean your risk of failing to achieve your mission objectives is high? Do you then get data about a time that everyone after the fact agrees was not representative of the climate you really wanted to sample? Such specific goals for a probe that doesn't have much choice about when it lands or how long it lasts, they scare me. Everyone would love the data from this mission, but the risks of it not really confirming or disproving the climatological theories that we want to confirm or disprove-- those risks need to be quantified. In other words, if you want it to see rain or fog, and we're certain these things occur on Titan, what are the chances it won't? Followed by everyone still believing that those things occur, but have never been observed in situ.

So if you then go back to the objectives that are guaranteed if the probe hits a lake and everything works: photos of a lake, the climate over the lake at one point in time, and the composition of one lake at one point. Everything more ambitious requires guarantees that the boat will work for quite awhile.
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Jason W Barnes
post Sep 16 2009, 11:04 PM
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QUOTE (stevesliva @ Sep 16 2009, 03:51 PM) *
Everything more ambitious requires guarantees that the boat will work for quite awhile.


My guess is that with the ASRGs, longevity won't be a problem.

- Jason
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vjkane
post Sep 16 2009, 11:48 PM
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QUOTE (Mark6 @ Sep 16 2009, 05:56 PM) *
Does anyone know what are the competing proposals for this round of Discovery missions?

This has been extensively covered at the Future Planets blog.

See:

Next Discovery Selection
Titan Mare Explorer and TIME
Ilion
Chopper
Venus Balloon
Post with full list of ASRG Discovery Concepts


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vjkane
post Sep 16 2009, 11:54 PM
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QUOTE (Drkskywxlt @ Sep 16 2009, 07:22 PM) *
I heard this presentation by Dr. Stofan at the Satellites Panel of the Decadal Survey (I was the notetaker). There was a great deal of interest by the Panelists and other members of the audience, but some skepticism as to whether this could ever fit in a Discovery budget. The reason Dr. Stofan's team believe they might have a shot at that $450M cost cap is that for this Discovery AO, the launch vehicle and ASRGs are provided as government furnished equipment. When you subtract those two giant costs out of the equation...you get a nearly New Frontiers-level budget for a Discovery mission. The mission is targeted for one of the larger "seas" at the North Pole and the probe could have a lengthy lifespan (during an extended mission) of possibly as much as 6 months, if memory serves. The instrumentation would be limited with an imager and meteorological/physical properties suite that could do some analysis of the lake fluid and weather conditions. A descent imager and thermometer would also be part of the deal. Comms would be DTE with a slow (but sufficient) data rate.

The IVO also got several eyebrows raised and lots of questions.

All Discovery missions get a launch vehicle outside of the $450M PI budget, so no advantage for the Titan Mare Explorer there. A mission that uses an ASRG also gets a free power source, but I don't think that solar panels for competing concepts are likely to be deal busters (and there are lots of other concepts for Discovery missions using ASRGs). I believe that Stofan's proposal also includes a mass spectrometer and gas chromatograph, unless that has been dropped very recently. Not really worth doing the mission in my opinion without that instrument.

The key for this proposal, like a lot of Discovery proposals, is the risk. Depending on how hard you judge it will be to develop the needed capabilities (such as surviving is a frigid place at the interface of two fluid that can suck away a lot of heat fast), a lot of proposals can fit within the Discovery budget. Review boards often seem to judge otherwise, and many a good sounding proposal has been thrown out as too risky for the budget. Whether that applies to this proposal, I have no idea.


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