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March OPAG presentations available
volcanopele
post Apr 11 2008, 07:01 AM
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Actually, the LORRI camera has an IFOV of 4.95 µm, while the EE NAC (as baselined last year) has an IFOV of 10 µm. The EE narrow angle camera has a similar resolution as Galileo's SSI.


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vjkane
post Apr 14 2008, 04:22 AM
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This week's Aviation Week as an article about the two outer planet Flagship proposals. The description of the Titan mission suggests that the orbiter would not orbit Titan, only Saturn. The OPAG presentation clearly says that the orbiter would orbit Titan after Saturn system studies. So, Aviation Week may be wrong, or this could be a new plan to fit within the budget and mass cap. (I hope the article is wrong!)

Here is the description from AW:

Titan/Saturn System Mission (TSSM) would image the lakes, streams and other extraordinary terrain of Saturn’s enigmatic moon, which is covered in organics—the building blocks of early life. The mission would center on a “Montgolfier” hot air balloon that would float for perhaps two years at low altitude in Titan’s methane atmosphere. The imaging balloon would also carry two or three surface probes with two-day lifetimes that could be dropped on areas of special interest. One probe, the methane lake boat, or submarine, would explore one of the most bizarre surfaces in the solar system. A companion TSSM orbiter would orbit Saturn and focus on Enceladus


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vjkane
post Apr 14 2008, 04:26 AM
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QUOTE (volcanopele @ Apr 11 2008, 07:01 AM) *
Actually, the LORRI camera has an IFOV of 4.95 µm, while the EE NAC (as baselined last year) has an IFOV of 10 µm. The EE narrow angle camera has a similar resolution as Galileo's SSI.

Jason, do you know the Cassini NA IFOV? And is there a simple formula for converting IFOV to m resolution at a given distance?


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rlorenz
post Apr 14 2008, 07:50 AM
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QUOTE (vjkane @ Apr 14 2008, 12:22 AM) *
This week's Aviation Week as an article about the two outer planet Flagship proposals. The description of the Titan mission suggests that the orbiter would not orbit Titan, only Saturn. The OPAG presentation clearly says that the orbiter would orbit Titan after Saturn system studies. So, Aviation Week may be wrong, or this could be a new plan to fit within the budget and mass cap. (I hope the article is wrong!)

Here is the description from AW:.....A companion TSSM orbiter would orbit Saturn and focus on Enceladus[/i]


I think AW has garbled this (maybe got mixed up with what *had* been proposed for TANDEM last year,
and what is being planned in the Joint NASA-ESA TSSM study)

TSSM would eventually enter orbit around Titan. Still being worked how long it would orbit Saturn
(and encounter Enceladus) before it does so.
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ugordan
post Apr 14 2008, 08:31 AM
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QUOTE (vjkane @ Apr 14 2008, 06:26 AM) *
Jason, do you know the Cassini NA IFOV? And is there a simple formula for converting IFOV to m resolution at a given distance?

Cassini NAC has an IFOV of 6 µrad. Simply multiplying that figure by distance of the target object gives you the pixel scale in input distance units. Note that to actually resolve objects at that distance, they'd need to be something like twice that in size.
For example, highest resolution image of Enceladus yet was taken from a slant distance of 319 000 m, multiply by 6E-6 rad and you get around 2 meters/pixel. The actual image was binned 2x2 so the pixel scale was reduced to 4 meters/pixel. That can resolve objects around 8 m in size and larger.


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vjkane
post Apr 14 2008, 02:59 PM
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QUOTE (rlorenz @ Apr 14 2008, 07:50 AM) *
TSSM would eventually enter orbit around Titan. Still being worked how long it would orbit Saturn
(and encounter Enceladus) before it does so.

I'd hoped that's the case. Being able to study Enceladus is a nice option of the new plan, although I suspect that the problems of carrying all the extra mass for fuel are giving the teams serious issues.


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vjkane
post Apr 15 2008, 01:37 AM
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QUOTE (rlorenz @ Apr 14 2008, 07:50 AM) *
I think AW has garbled this (maybe got mixed up with what *had* been proposed for TANDEM last year,
and what is being planned in the Joint NASA-ESA TSSM study)

AWST also said that the in situ probe would be a balloon with three dropped landers. Has this been decided, or is this still just one of the options?


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DFortes
post Apr 15 2008, 09:55 AM
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QUOTE (rlorenz @ Apr 14 2008, 08:50 AM) *
I think AW has garbled this (maybe got mixed up with what *had* been proposed for TANDEM last year,
and what is being planned in the Joint NASA-ESA TSSM study)



Spaceflight Now and Astronomy Now are carrying similar 'misinformation'

http://www.astronomynow.com/news/080404laplacetandem/

Don't believe everything you read...
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rlorenz
post Apr 15 2008, 11:44 AM
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QUOTE (vjkane @ Apr 14 2008, 09:37 PM) *
AWST also said that the in situ probe would be a balloon with three dropped landers. Has this been decided, or is this still just one of the options?


Nothing has been decided yet, but these are the options being explored. Remains to be seen
whether all of these can be accommodated. It will be some months before the study is
complete
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Stephen
post Apr 17 2008, 03:56 AM
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After reading the proposal for the Jovian OPF mission at the OPAG site what strikes me most is that it's really three separate missions bundled together and presented as one OPF! Not only would NASA, ESA, and JAXA each have their own orbiter, each of those orbiters would be launched on separate launch vehicles at (maybe widely varying) occasions.

Granted that each of those orbiters would have differing goals, but then that's hardly the point! Consider NASA's contribution, the Europan Orbiter. The report estimates it will cost $2.4 billion. Unfortunately, NASA only has $2.1 billion in the kitty to pay for it (which in turn has, not unnaturally, produced what I take to be a certain amount of handwringing). However, instead of ESA and JAXA riding to the rescue to make up the shortfall they will instead be spending their money on their own orbiters.

Indeed if the ESA and JAXA will be contributing anything (other than science personnel) to the EO it is not spelt out in that document as far as I can make out.

That is not say all three orbiters are not exciting, worthwhile endeavours, but is that really the way these international space missions are supposed to work?

On the face of it it's difficult to call this one an international mission at all. With all due respect to those who put that presentation together it looks more like three national missions bundled together for marketing purposes.
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vjkane
post Apr 17 2008, 05:48 AM
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QUOTE (Stephen @ Apr 17 2008, 03:56 AM) *
On the face of it it's difficult to call this one an international mission at all. With all due respect to those who put that presentation together it looks more like three national missions bundled together for marketing purposes.
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Stephen

I would disagree. Each mission addresses key areas of Jovian science that no single craft can. One orbits Europa. Another conducts long term studies of Io and Jupiter and possibly orbits Ganymede. Another studies the magnetosphere in a second location, which has been a long term goal of the fields and particles community for Jupiter. Instrument development and science teams would be shared across all three missions.


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Stephen
post Apr 17 2008, 10:38 AM
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QUOTE (vjkane @ Apr 17 2008, 03:48 PM) *
Each mission addresses key areas of Jovian science that no single craft can.

I do not doubt that at all, especially given the descoping of the version of the Europan Orbiter now being proposed versus the one proposed in this 2007 report to OPAG (caution! 95 mb PDF file). The one now being proposed appears to be the cheaper ($2.4 billion) "floor mission" rather than more expensive ($3.3 billion) "baseline mission" (see page 4-4 of that earlier report); and given that there is still a shortfall of some $300 million ($2.4 billion estimate vs $2.1 billion funding available) then chances are the EO may face more descoping before the project even gets the green light, much less flies--unless somebody rides to the rescue with more cash. (And given the past history of NASA projects ballooning in costs as development progresses even that additional descoping may not be the end of the bad news for the EO project.)

A more sensible solution (just MHO) would have been for the Jovian OPF guys to settle on one or the other--either an EO or an JSO--to which both NASA and the ESA would contribute. By trying to have both (plus a possible Japanese orbiter) their ambitions may well wind up exceeding their funding levels.

QUOTE (vjkane @ Apr 17 2008, 03:48 PM) *
Instrument development and science teams would be shared across all three missions.

Glad to hear it.

But tell me: how much of NASA's $2.1 billion for the next OPF will be spent on ESA's JSO and how much ESA funding will be spent on NASA's EO?

As far as I can make out there isn't enough for NASA to pay for that $2.4 billion EO plus make a sensible contribution to the JSO (which I see from the 2007 JSO report here (caution! 45 mb PDF file) will cost $3.1 billion for the "baseline mission" and $2.7 billion for the "descope mission" (page 1-4).)

By my maths that means (assuming the descoped version of each) EO + JSO == $4.8 billion!

How much of that is NASA going to be contributing towards?

With Cassini NASA paid for 80% of the mission, with the ESA and the Italians paying the remainder. Will that be the split again? If so, then someone will need to tell Congress to come with a couple of billion dollars more!

On the other hand given NASA's present committment isn't enough to even cover the cost of EO just how much will it be able to contribute towards the JSO?

As far as I can see the major rationale for these international missions is to offset costs. If all NASA can contribute to the JSO is a few token pennies while the ESA won't be able to contribute much to the EO because it will have a $2.7 billion bill to pay for the JSO then will these really be INTERnational missions or will they turn out to be merely national ones with a little personnel mixing from foreign agencies?
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djellison
post Apr 17 2008, 10:45 AM
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Unfortunately, it's very VERY hard to do international colab at any level other than the hard-cut offs ( i.e. Cassini / Hugyens ) or the instrument level ( although look at the Phoenix MET for how hard that's been). The transferring of pure cash is not a wise move in terms of public opinion.

Other than contributing whole spacecraft, or just instruments - I'm not sure what you're suggesting Stephen.


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vjkane
post Apr 17 2008, 02:38 PM
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QUOTE (Stephen @ Apr 17 2008, 10:38 AM) *
A more sensible solution (just MHO) would have been for the Jovian OPF guys to settle on one or the other--either an EO or an JSO--to which both NASA and the ESA would contribute. By trying to have both (plus a possible Japanese orbiter) their ambitions may well wind up exceeding their funding levels.

As far as I can make out there isn't enough for NASA to pay for that $2.4 billion EO plus make a sensible contribution to the JSO (which I see from the 2007 JSO report here (caution! 45 mb PDF file) will cost $3.1 billion for the "baseline mission" and $2.7 billion for the "descope mission" (page 1-4).)

By my maths that means (assuming the descoped version of each) EO + JSO == $4.8 billion!

I agree that in a perfect world, the best use of ESA's money for Jupiter would be to add an extra $600-800M (I forget the euro figures) into a single more capable craft. However, there are strong justifications for a second craft to do studies that a Europa-bound orbiter wouldn't want to linger around to do.

I do not agree with your budget analysis. ESA's craft (without instrument costs, which are borne by the individual countries) is capped at that $600-800M. ESA will not be spending $2.7-3.1B. Based on Juno (which will cost about the same with instrument costs), a solar powered Jovian orbiter can be built for this price range. I have serious doubts about whether it can also orbit Ganymede, but it could do dozens of flybys at different longitudes and lattitudes. I think a craft that observes Jupiter and Io for a number of years and conducts many flybys of Ganymede is a good candidate mission. You apparently disagree, and that's what's makes forums interesting for all.


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Greg Hullender
post Apr 18 2008, 04:26 PM
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I don't suppose the Euro being worth twice as much now as it was a few years ago helps? I'd like to think that means the Europeans could contribute twice as much, but somehow I think it doesn't work that way. :-)

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