Author Topic: Proposed Europa Missions  (Read 347470 times)

Offline spectre9

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Re: Proposed Europa Missions
« Reply #20 on: 08/12/2012 11:27 PM »
Fly by doesn't mean that the distance for observations is longer.

It just means the probe doesn't stay at the one moon.

It flies in takes the readings and flys away. Obviously doing it like this takes a lot longer to image the full surface but I do think it's worth it.

It's like Cassini how it does a fly by of Titan or Enceladus every now and then.

The orbiter/lander mission can come later.

Thanks for clarification about what the hints you were dropping were about Blackstar.

I'm guessing that a cut down fly by mission from the ones in the already posted presentations are what is being considered?

C'mon outer planets!!!  8)

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #21 on: 08/13/2012 12:18 AM »
I'm guessing that a cut down fly by mission from the ones in the already posted presentations are what is being considered?

I didn't say "cut down."

I said cheaper...

(and, surprisingly, better too--put another way, more capability at less money)
« Last Edit: 08/13/2012 03:00 PM by Blackstar »

Offline spectre9

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Re: Proposed Europa Missions
« Reply #22 on: 08/13/2012 12:24 AM »
Ok thanks for the added clarification.

Now I'm excited again but I still realise that outer planets has a fight ahead of them to get anything approved in the current environment.

Offline jnc

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Re: Proposed Europa Missions
« Reply #23 on: 08/13/2012 02:34 AM »
It just means the probe doesn't stay at the one moon.

Got that, thanks.

Quote
Obviously doing it like this takes a lot longer to image the full surface

They might get full surface imagery, but not at the level of detail the orbiter would give them. If you look at pg. 12 of the "Mission Studies" presentation, you'll see that the orbiter gives pretty good coverage at 100 m/pixel.

The multiple passes of the flyby won't give anything like as good coverage at high resolutions; check out the ground tracks (pg. 17 of the "Mission Studies") and the Topographic Imager coverage chart (next page).

Of course, 100 m/pixel is not enough resolution to really check out for landing spots, a point made on pp. 17-18 of the "Pappalardo Lander Forum" presentation. And while looking for the cite on that, I noticed that the "Lander Technical" presentation says, on pg. 10, that they need .5 m/pixel for a reasonably safe landing. (Which I guess kind of answers the question in my previous post...)

I see on pg. 11 that they're going to do hi-res imaging, and site selection from that imaging, as phases 1 and 2 of the landing process, but it's not clear from any of this material if they do that from the initial orbit (parameters not given), or the 200x5 km 'pre-landing' orbit; the timeline on pg. 9 makes it sound like it's from the inital orbit.

Noel
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Offline spectre9

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Re: Proposed Europa Missions
« Reply #24 on: 08/13/2012 03:05 AM »
For a nominal mission length yes I would agree that the orbiter is going to get the better mapping but consider this.

Cassini was a 4 year mission.

It's been going for 8 and doesn't look like the probe will die any time soon.

The flyby can also get closer to the surface. Some of those tracks are <25km. If it's just the type of camera stopping the detail from being better possibly the instrumentation could be altered?

It seems to me like these 2 separate spacecraft are designed to be the one mission so if one is flown and the other is not that would be a different mission design.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #25 on: 08/13/2012 04:10 AM »
The multiple passes of the flyby won't give anything like as good coverage at high resolutions; check out the ground tracks (pg. 17 of the "Mission Studies") and the Topographic Imager coverage chart (next page).

Hmmm...

I'm not sure when the next OPAG meeting is, but you might check on that.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #26 on: 09/24/2012 11:42 PM »
Okay, I'll post the slides later, but here's the deal:

JPL has been studying the Europa Clipper mission since around May and now thinks that it is possible that they could do the mission with solar. That would reduce the cost of the mission, and possibly also decrease risk, since the ASRGs are considered risky. (So, while I previously posted that solar won't work for Europa missions, I may eventually have to eat my hat, with a heaping of crow.)

That's not a done deal, however. One of the big problems is that the Clipper would go into shadow for a long time (I think I heard them say around six hours) and that requires batteries and batteries are heavy. There are also other problems, such as the radiation damage to the solar panels and the issue of cold--a Clipper mission would get more radiation and more cold than Juno.

Another potential problem is jitter. The panels could introduce vibration. Now why is that important?

Well, it turns out that one of the other big things they have been looking at is adding a high-resolution camera to the Clipper to take photos of potential landing sites for a future mission. Apparently the lander mission that they studied got people sufficiently excited that they think that the lander is feasible, provided that you could get good landing site data.

I didn't hear the presentations that well, but the camera adds something like $200 million to the mission, pushing it over a cost cap (of, I think, $2 billion). Using solar instead of ASRGs then brings the cost down. Not sure if it brings it back into the cost cap, but it helps a lot.

Now let me be clear on this: THERE IS NO MONEY TO DO THIS MISSION. A senior planetary official made that clear at the end of the presentation--just because a study has reduced the cost doesn't mean that there is actual money to do a Europa flagship mission. But it does show that there is promise here.

I'll post the slides later.
« Last Edit: 09/24/2012 11:43 PM by Blackstar »

Offline robertross

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Re: Proposed Europa Missions
« Reply #27 on: 09/25/2012 12:26 AM »
Thanks Blackstar!

They may not have the money, but perhaps it could generate enough interest outside the science community (and in the political arena) to find funding in a gov't/private partnership (doubt that would happen, but you never know).
Remembering those who made the ultimate sacrifice for our rights & freedoms, and for those injured, visible or otherwise, in that fight.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #28 on: 09/25/2012 01:50 AM »
They may not have the money, but perhaps it could generate enough interest outside the science community (and in the political arena) to find funding in a gov't/private partnership (doubt that would happen, but you never know).

No. Impossible. Price tag is $2 billion. Nobody foots serious cash for stuff that they assume the government should fund. This is going to be the big problem for B612 and their asteroid search spacecraft.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #29 on: 09/25/2012 04:28 AM »
Here's some of it.

Offline simonbp

Re: Proposed Europa Missions
« Reply #30 on: 09/25/2012 02:53 PM »
That is interesting.

The solution to the jitter may be a separate scan platform (like Voyager), which could both cancel out the jitter and allow more imaging during the pass. This would add to the cost, but solar+scan platform could still be cheaper than with an ASRG.

Offline robertross

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Re: Proposed Europa Missions
« Reply #31 on: 09/25/2012 03:21 PM »
They may not have the money, but perhaps it could generate enough interest outside the science community (and in the political arena) to find funding in a gov't/private partnership (doubt that would happen, but you never know).

No. Impossible. Price tag is $2 billion. Nobody foots serious cash for stuff that they assume the government should fund. This is going to be the big problem for B612 and their asteroid search spacecraft.

aww shucks.
Remembering those who made the ultimate sacrifice for our rights & freedoms, and for those injured, visible or otherwise, in that fight.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #32 on: 09/25/2012 04:09 PM »
Here is the first half of the presentation.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #33 on: 09/25/2012 04:09 PM »
Here is the rest of the presentation.

Offline Star One

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Re: Proposed Europa Missions
« Reply #34 on: 09/25/2012 09:34 PM »
With that kind of price tag no one is going to fund this anytime soon are they?

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #35 on: 09/25/2012 11:20 PM »
With that kind of price tag no one is going to fund this anytime soon are they?

The quick answer is "no." The more complex answer is that OMB has apparently decided to not approve any flagships for planetary science, so it doesn't matter which ones get proposed, in what order, there is simply no support for doing it.

That said, the real action now is in the Mars area. Complex story, but you can find the threads.

Offline robertross

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Re: Proposed Europa Missions
« Reply #36 on: 09/25/2012 11:39 PM »
Here is the rest of the presentation.

Hot off the presses! Thank you Sir.
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Offline robertross

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Re: Proposed Europa Missions
« Reply #37 on: 09/26/2012 12:06 AM »
Very cool to see a 0.5m/pixel camera on the enhanced Clipper. That should be more than adequate. :)

Really like the margins.

I also like the Magnetometer boom addition.

Using SLS: 6 years to 2.8 years!! Wish it was affordable (but nowhere near holding my breathe...maybe pre-breathing) Really like the nanosat concept tied to it.

(smal spelling issue at bottom of Part 2, page 30)
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Offline Solman

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Re: Proposed Europa Missions
« Reply #38 on: 09/26/2012 01:33 AM »
 Just want to suggest that a solar concentrator might have many advantages for a Europa mission. L'Garde has demonstrated one that focuses 17KW thermal roughly per KW thermal. Around 170W/kg at Saturn even. My mind wandered toward Enceladus and sampling of volcanic emissions by an orbiter ...
 A concentrator can double as a high baud antenna for such an outer planet mission due to its size.
 The solar cells that use concentrated sunlight have the highest efficiency - over 40% - and best specific power.
 The concentrator can power a solar thermal engine for LEO to escape saving much time over solar electric and power a solar electric engine after that.
 The concentrator can double as a radio telescope for some very long baseline interferometry and SAR at Europa.
« Last Edit: 09/28/2012 04:08 PM by Solman »

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #39 on: 09/26/2012 01:56 AM »
Using SLS: 6 years to 2.8 years!! Wish it was affordable (but nowhere near holding my breathe...maybe pre-breathing) Really like the nanosat concept tied to it.

One of the people who worked on the study is really enthusiastic about SLS for this mission. My impression is that he's the only one.

It's simple: a really big rocket can give you really great margins for missions like this, and everybody would just love to have more mass and more delta-v to play with. And theoretically, you could possibly save money on your spacecraft design because you don't have to design anything to be extremely light weight, which always costs a lot.

The problem is programmatics--fitting a science spacecraft onto a non-existent rocket that actually belongs to another part of NASA, and which will be too expensive on a per-unit basis for the science part of NASA to afford. The science guys have said that they would only really consider this if the HEO part of NASA agreed to foot the bill for the launch, essentially providing the SLS launch for free for a science payload. Why would HEOMD agree to do that? They'd be giving away their money. And even if they agreed to it, there's no guarantee to the science guys that they would stick to that decision, and three years into the program the science program could find itself suddenly being stuck with the launch costs and having to cannibalize other parts of their portfolio.

So from a programmatic perspective, it is far safer for the science program to simply design for a rocket that already exists and that they already have some experience with. Now if you assume that SLS gets built, and flies successfully, and this Europa mission gets approved, then SLS might be an option. But it would be crazy to baseline it now.
« Last Edit: 09/26/2012 02:43 AM by Blackstar »