Author Topic: Proposed Europa Missions  (Read 354794 times)

Offline robertross

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Re: Proposed Europa Missions
« Reply #40 on: 09/26/2012 02:28 PM »
and that is a 100% perfect assessment of the situation, and totally agree.

I might only add that they (HEOMD) might consider doing this if they could do a dual launch (launch of opportunity) for something else, like an empty depot, another spacecraft, or goodness knows what. But not likely.
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Offline Blackstar

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Re: Proposed Europa Missions
« Reply #41 on: 09/26/2012 02:34 PM »
and that is a 100% perfect assessment of the situation, and totally agree.

I might only add that they (HEOMD) might consider doing this if they could do a dual launch (launch of opportunity) for something else, like an empty depot, another spacecraft, or goodness knows what. But not likely.

I do think it would be an interesting--possibly worthwhile--exercise to evaluate the benefits of heavy lift for planetary missions. I know of no detailed studies that have done it. When we did our assessment of Constellation for science, we didn't have any planetary missions to look at, so all we could really do was discuss the C3 and payload benefits without having anything more.

Dual manifesting has some potential in niche cases, but would require study. There was a ridiculous study about five years ago called CEMMENT (Worst. Name. Ever.) that looked at the possibility of doing an engineering test of a human lander at Mars that would be loaded up with science experiments. The basic idea was reasonable, but they went crazy with it, thinking that because they would have a lot of payload and volume, they should fill it all up with sciency stuff. The end result was a science fiction fantasy, because there was no way that, even if they got the launch vehicle and lander for free, the science program could afford to build all the science spacecraft.

Offline robertross

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Re: Proposed Europa Missions
« Reply #42 on: 09/26/2012 03:03 PM »
and that is a 100% perfect assessment of the situation, and totally agree.

I might only add that they (HEOMD) might consider doing this if they could do a dual launch (launch of opportunity) for something else, like an empty depot, another spacecraft, or goodness knows what. But not likely.

I do think it would be an interesting--possibly worthwhile--exercise to evaluate the benefits of heavy lift for planetary missions. I know of no detailed studies that have done it. When we did our assessment of Constellation for science, we didn't have any planetary missions to look at, so all we could really do was discuss the C3 and payload benefits without having anything more.

Dual manifesting has some potential in niche cases, but would require study. There was a ridiculous study about five years ago called CEMMENT (Worst. Name. Ever.) that looked at the possibility of doing an engineering test of a human lander at Mars that would be loaded up with science experiments. The basic idea was reasonable, but they went crazy with it, thinking that because they would have a lot of payload and volume, they should fill it all up with sciency stuff. The end result was a science fiction fantasy, because there was no way that, even if they got the launch vehicle and lander for free, the science program could afford to build all the science spacecraft.

I don't know if a study was done per se, but using the Ares V (more like Ares VI...hehe) for science missions was definitely persued (more like flaunted) by NASA (obviously to gain support). Those docs are here on the public side or the L2 side.

Edit: here it is:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070038373_2007037046.pdf
« Last Edit: 09/26/2012 03:10 PM by robertross »
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Offline vjkane

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Re: Proposed Europa Missions
« Reply #43 on: 09/26/2012 04:42 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.

I think that you have to look at a Europa mission as a long game.  With JWST overruns and manned spaceflight budget challenges, this is not the time to ask for new Flagship missions in any of the science disciplines.  However, this is the first Europa mission proposal that comes in at $2B and doesn't require significant new technology development.  I believe that if the space community keeps Europa as a focus, then getting a new start after JWST flies later this decade would be a reasonable goal to work towards.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #44 on: 09/26/2012 06:21 PM »
I don't know if a study was done per se, but using the Ares V (more like Ares VI...hehe) for science missions was definitely persued (more like flaunted) by NASA (obviously to gain support). Those docs are here on the public side or the L2 side.

Edit: here it is:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070038373_2007037046.pdf

You linked to a paper about using heavy lift for astronomy. That's an obvious option.

The NRC did a study around 2008 or so on using Constellation for science missions. When we did that study we had a lot of options for astronomy and other missions using heavy lift. We did not have any previous studies of using it for planetary missions. I was pointing out that there could be value at looking at this issue beyond simply additional mass and C3. It might allow you to do innovative orbits, or more complex mission architectures (not necessarily more complex spacecraft--for example, you could simply add fuel and do better things with your orbits). And the impact on spacecraft design could be significant, but so far all the discussions have been superficial.

What this really comes down to is a cost-benefit trade that nobody has really made. That could be summed up like this: "The HLV rocket costs you an extra $700 million for launch; can you save more than $700 million in spacecraft design using heavy lift?" Nobody has really looked at those trades.
« Last Edit: 09/26/2012 07:59 PM by Blackstar »

Offline spectre9

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Re: Proposed Europa Missions
« Reply #45 on: 09/26/2012 11:33 PM »
Thanks very much for the information provided Blackstar.

Interesting that the mission can be traded to solar.

Asking for the money or not this is a mission that needs to be done.

The decadal survey says so. No MSR = Europa. That's the flagship priority. The MSR guys just can't let go yet.

The next survey might not be so sympathetic to their cause. Could awesome discoveries made by Curiosity push the priority for MSR back? I mean that's the whole reason for having something like SAM isn't it? So you can test the rocks at Mars without bringing them back.

I like the idea of using big rockets for exploring, the ice giants are so far away something like SLS really helps.

At $2 billion this is a cheap flagship for the science that can be had. These big questions about Europa have had planetary scientists giddy for years now, it's time to get some answers.  8)

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #46 on: 09/27/2012 01:35 AM »
1-Interesting that the mission can be traded to solar.

2-The decadal survey says so. No MSR = Europa. That's the flagship priority. The MSR guys just can't let go yet.

3-I mean that's the whole reason for having something like SAM isn't it? So you can test the rocks at Mars without bringing them back.

1-It might be possible to do with solar. The studies are not done yet.

2-No, that's not really how it works. (Trust me, I was there.) The first choice in the decadal was MSR. The Office of Management and Budget decided to not do any flagships at all. It is not the case that because OMB said no to sample return that we now go on to Europa.

3-No. There are three, maybe four reasons to do sample return:

-the samples can be analyzed on Earth by hundreds of different research teams
-the samples can be analyzed for decades after they return (the best science done on Apollo samples is being done TODAY with modern instruments)
-you can use a far greater number of instruments to analyze samples on Earth than you can on a planetary body

One additional argument in favor of sample return is discovery--when you provide the samples to a broad group of people, rather than the narrow team that works on a single space mission, you can get discoveries that you never would have otherwise gotten.

The SAM instrument on Curiosity is an impressive piece of space hardware. It is very primitive and limited in capability compared to even a modest university chemistry lab on Earth. We have no way to squeeze all the incredibly sophisticated instruments that exist on Earth into a small package on a spacecraft. SAM is no substitute for bringing back the materials.
« Last Edit: 09/27/2012 01:36 AM by Blackstar »

Offline baldusi

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Re: Proposed Europa Missions
« Reply #47 on: 09/27/2012 10:23 PM »
I still think about the C3 benefits of a Heavy launcher (or a depot architecture). How do you trade the possibility of basing one mission on the results of previous one? If you have 6 to 8 years of travel, you can't get more than one mission per decade, if you are lucky, that need the previous one. On the other hand, at 2 to 3 years of transit, you can do twice the number. It get's interesting if you can use the previous missions assets. Say you want to send a lander to Europa. Communications with Earth is very difficult. May be, if it only has to wait for five years, there's a way to put it on hibernation and use the orbiters communication capabilities to support the lander. But if it took longer, the degradation would be too great, even in case of hibernation and protecting shrouds.
On hte other hand, a heavy launcher could send the communication orbiter AND the lander on the same mission. I'm just trying to get creative.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #48 on: 09/28/2012 01:50 AM »
I still think about the C3 benefits of a Heavy launcher (or a depot architecture). How do you trade the possibility of basing one mission on the results of previous one? If you have 6 to 8 years of travel, you can't get more than one mission per decade, if you are lucky, that need the previous one. On the other hand, at 2 to 3 years of transit, you can do twice the number. It get's interesting if you can use the previous missions assets. Say you want to send a lander to Europa. Communications with Earth is very difficult. May be, if it only has to wait for five years, there's a way to put it on hibernation and use the orbiters communication capabilities to support the lander. But if it took longer, the degradation would be too great, even in case of hibernation and protecting shrouds.
On hte other hand, a heavy launcher could send the communication orbiter AND the lander on the same mission. I'm just trying to get creative.

I think that is the kind of trade it would be interesting to perform. But the key trade to explore would be cost reduction in missions. For instance, if you decrease the transit time and increase the mass margins and fuel margins and things like that, could you bring the cost of the mission down significantly? I've only seen very thin speculation about this, but nobody has actually gone into it in any depth.

Offline baldusi

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Re: Proposed Europa Missions
« Reply #49 on: 09/28/2012 08:11 PM »
[...]

I think that is the kind of trade it would be interesting to perform. But the key trade to explore would be cost reduction in missions. For instance, if you decrease the transit time and increase the mass margins and fuel margins and things like that, could you bring the cost of the mission down significantly? I've only seen very thin speculation about this, but nobody has actually gone into it in any depth.

My intuition, is that any sort of increase in structural or payload mass due to lowering the cost, will be offset by the increased fuel and thrust increase needed. After all, the rocket formula is exponential on the pmf. Besides, AFAIK, the bulk of cost it on certification and testing, not on the materials themselves.
The other issue, and I think this is the core issue, is: how do you keep the scientists and engineers from adding features and science payload that actually increases the cost since they have weight and volume to spare? In other words, if the budget was made reasonably, the biggest danger is the project management's own desire for a better mission.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #50 on: 09/28/2012 09:03 PM »
1-My intuition, is that any sort of increase in structural or payload mass due to lowering the cost, will be offset by the increased fuel and thrust increase needed. After all, the rocket formula is exponential on the pmf. Besides, AFAIK, the bulk of cost it on certification and testing, not on the materials themselves.

2-The other issue, and I think this is the core issue, is: how do you keep the scientists and engineers from adding features and science payload that actually increases the cost since they have weight and volume to spare? In other words, if the budget was made reasonably, the biggest danger is the project management's own desire for a better mission.

1-I don't think that's an issue here because the initial margins are so huge. We're talking about throwing a relatively small spacecraft to the outer planets. With a heavy lift vehicle you can easily throw twice the mass. So if you give the designers 50% more margin to play with, the other penalties don't really bite.

2-Yes, that is an issue. But you're going to be cost constrained from the start. The way to do the initial trade is to take a spacecraft designed for a smaller vehicle and then tell the designers "You cannot add instruments, but you can add mass, fuel, operations, and other margins." I imagine that in some missions that would cause the scientists to hyperventilate and faint because they'd love to have those things even without more instruments. For example, the key limitation is radiation. If you told the scientists that instead of a 180 day mission they could have enough shielding for a five-year mission, they would be more than happy.

Offline baldusi

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Re: Proposed Europa Missions
« Reply #51 on: 09/29/2012 03:46 PM »
1-My intuition, is that any sort of increase in structural or payload mass due to lowering the cost, will be offset by the increased fuel and thrust increase needed. After all, the rocket formula is exponential on the pmf. Besides, AFAIK, the bulk of cost it on certification and testing, not on the materials themselves.

2-The other issue, and I think this is the core issue, is: how do you keep the scientists and engineers from adding features and science payload that actually increases the cost since they have weight and volume to spare? In other words, if the budget was made reasonably, the biggest danger is the project management's own desire for a better mission.

1-I don't think that's an issue here because the initial margins are so huge. We're talking about throwing a relatively small spacecraft to the outer planets. With a heavy lift vehicle you can easily throw twice the mass. So if you give the designers 50% more margin to play with, the other penalties don't really bite.
But more mass means higher thrust engines. Higher mass means higher momentum of inertia, thus, bigger reaction wheels and thrusters, plus thruster fuel, etc. Bigger fuel tanks in relation to the payload also means a more over sized control authority when the tanks are near empty, thus requiring higher precision firings and more sophisticated control. Then you have to certify and test everything. I seriously doubt you would save much. The only way I see this saving money is if they can use a legacy platform and parts that are already designed and certified for the expected environment. If said parts and/or platform was too heavy for the "small" LV, then yes, using a more powerful rocket might actually lower the cost. But you won't save much, if anything, by doing it custom.
You know very well that planetary missions have very particular requirements that nobody else needs. You have to tolerate the environment from Venus to the outer planets (if you do a VVEGA maneuver), the radiation degradation environment is unique to deep space probes, and the thermal environment is very particular. You might save a bit if you can use a bigger LV to save the Venus Gravity assist, and thus you don't have to design for that thermal environment. Of course, we are talking about a mission already planned with a conservative estimation and good margins. If you want to put a 2.5tonnes mission on a 1.9tonnes LV, of course it's going to be cheaper to put it on a bigger LV than making enough technological advances to reduce the weight enough. But going from an EELV to SLS the jump in performance is so huge, that's not the case.

Quote
2-Yes, that is an issue. But you're going to be cost constrained from the start. The way to do the initial trade is to take a spacecraft designed for a smaller vehicle and then tell the designers "You cannot add instruments, but you can add mass, fuel, operations, and other margins." I imagine that in some missions that would cause the scientists to hyperventilate and faint because they'd love to have those things even without more instruments. For example, the key limitation is radiation. If you told the scientists that instead of a 180 day mission they could have enough shielding for a five-year mission, they would be more than happy.
I quite get how it would be ideally. But you have to plan the system for the "misbehaving". And in any case, more mass usually means more cost. You can add some layers of composite Ti/Br to protect the electronics. But then you have to actually certify that for a five year radiation and thermal environment. That means weeks, if not months on environmental testing chambers and more time in from of the accelerator. And then, how do you protect your sensors? You added protection to your electronics but now you have to develop hardened sensors, which you can't protect unless you don't want to get any reading. Might be an option if you want to take extended time domain samples. But then you have to design, certify, integrate and test a sensor protection system. More money and complexity.
And again, I think you can do that if you jump from an Atlas V531 to a 551. But even from a Falcon Heavy to SLS there's so much differential, that I can't think of any use save delta-v that will be "cheaper".

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #52 on: 09/30/2012 01:56 PM »
1-My intuition, is that any sort of increase in structural or payload mass due to lowering the cost, will be offset by the increased fuel and thrust increase needed. After all, the rocket formula is exponential on the pmf. Besides, AFAIK, the bulk of cost it on certification and testing, not on the materials themselves.

2-The other issue, and I think this is the core issue, is: how do you keep the scientists and engineers from adding features and science payload that actually increases the cost since they have weight and volume to spare? In other words, if the budget was made reasonably, the biggest danger is the project management's own desire for a better mission.

1-I don't think that's an issue here because the initial margins are so huge. We're talking about throwing a relatively small spacecraft to the outer planets. With a heavy lift vehicle you can easily throw twice the mass. So if you give the designers 50% more margin to play with, the other penalties don't really bite.
But more mass means higher thrust engines. Higher mass means higher momentum of inertia, thus, bigger reaction wheels and thrusters, plus thruster fuel, etc. Bigger fuel tanks in relation to the payload also means a more over sized control authority when the tanks are near empty, thus requiring higher precision firings and more sophisticated control. Then you have to certify and test everything. I seriously doubt you would save much. The only way I see this saving money is if they can use a legacy platform and parts that are already designed and certified for the expected environment. If said parts and/or platform was too heavy for the "small" LV, then yes, using a more powerful rocket might actually lower the cost. But you won't save much, if anything, by doing it custom.
You know very well that planetary missions have very particular requirements that nobody else needs. You have to tolerate the environment from Venus to the outer planets (if you do a VVEGA maneuver), the radiation degradation environment is unique to deep space probes, and the thermal environment is very particular. You might save a bit if you can use a bigger LV to save the Venus Gravity assist, and thus you don't have to design for that thermal environment. Of course, we are talking about a mission already planned with a conservative estimation and good margins. If you want to put a 2.5tonnes mission on a 1.9tonnes LV, of course it's going to be cheaper to put it on a bigger LV than making enough technological advances to reduce the weight enough. But going from an EELV to SLS the jump in performance is so huge, that's not the case.

Quote
2-Yes, that is an issue. But you're going to be cost constrained from the start. The way to do the initial trade is to take a spacecraft designed for a smaller vehicle and then tell the designers "You cannot add instruments, but you can add mass, fuel, operations, and other margins." I imagine that in some missions that would cause the scientists to hyperventilate and faint because they'd love to have those things even without more instruments. For example, the key limitation is radiation. If you told the scientists that instead of a 180 day mission they could have enough shielding for a five-year mission, they would be more than happy.
I quite get how it would be ideally. But you have to plan the system for the "misbehaving". And in any case, more mass usually means more cost. You can add some layers of composite Ti/Br to protect the electronics. But then you have to actually certify that for a five year radiation and thermal environment. That means weeks, if not months on environmental testing chambers and more time in from of the accelerator. And then, how do you protect your sensors? You added protection to your electronics but now you have to develop hardened sensors, which you can't protect unless you don't want to get any reading. Might be an option if you want to take extended time domain samples. But then you have to design, certify, integrate and test a sensor protection system. More money and complexity.
And again, I think you can do that if you jump from an Atlas V531 to a 551. But even from a Falcon Heavy to SLS there's so much differential, that I can't think of any use save delta-v that will be "cheaper".

You seem to be under the mistaken assumption that I'm an advocate for this. I was pointing out that I think it might be worthwhile to do a trade study. If you're looking to argue about this with somebody, you'll have to find somebody else.

And the actual advocates of this have claimed that more mass does not automatically mean more cost if you allocate that additional mass to "dumb" parts of the spacecraft, such as structure, fuel, shielding, etc. I just think it might be worth looking into that.
« Last Edit: 09/30/2012 08:16 PM by Blackstar »

Offline baldusi

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Re: Proposed Europa Missions
« Reply #53 on: 10/01/2012 03:17 PM »
Quite on the contrary. I have you in very high regard and really enjoy exchanging ideas with you. What I'm trying to say, and I apology if my term come sort of too candid, it's due to subtleties of the English language that I miss. What I do say is that for a certain "small" range, in some parts, you can trade cost for weight. But also, SLS is so out there in payload capabilities, that I find it extremely unlikely that it would offer any opportunity of lowering costs by adding that much weight. I also believe such trade studies are extremely hard to do in a general sense, because it depend both on unknown factor and the margins of the rest of the assemblies.
I would love a study on general patterns of weight trades that work. And an investigation on non weight savings that can be achieved if you have a significantly bigger LV (say optimizing trajectories for cost rather than delta-v, trading comm costs on the spacecraft with DSN time, etc.).

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #54 on: 10/01/2012 03:31 PM »
Don't get me wrong, I'm not offended. I'm just not advocating this as an idea, and I don't want words put in my mouth, because I need the room for inserting my foot in there.

I do think that it MIGHT be possible to lower the cost of an outer planets spacecraft by taking the mass issue out of the equation. But I also think that the SLS vehicle cost is going to wipe that out. You would have to save a LOT of money on a spacecraft to justify the launch vehicle cost. Suppose that an Atlas is going to cost you $300 million and an SLS is going to cost you $1 billion. You would have to save more than $700 million on the spacecraft simply to justify the change in launchers.

I also think that you went off on a tangent there that does not really lead to anything. All of these spacecraft are custom designed. They don't use standard equipment. So, for instance, just because the spacecraft is bigger (with SLS) and this requires bigger control moment gyros, does not mean that the cost will go up because of that. In fact, the argument is that the cost should go down overall because all of these components can be built with bigger margins--no need to try innovative and risky design features just to squeeze half a kilogram of mass out of the system.

That said, there are other things that this could do that I think it might be worthwhile to explore. For instance, if you could double the amount of propellant on your spacecraft, you might be able to do more things with that spacecraft that you would never consider doing. It doesn't just extend the lifetime, it could mean that you could visit more moons at Jupiter, for instance. It could really open up the trade space.

But I also think that doing a study like this might be really premature now. It might only make sense to do this after there is an SLS flying, when you have a good idea about the capabilities and the costs of the rocket.

Offline Star One

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Re: Proposed Europa Missions
« Reply #55 on: 12/14/2012 02:11 PM »
Another proposal the Europa Clipper has been outlined in an article on Space.com

Quote
But NASA is also thinking about ways to investigate the possible habitability of Europa, Jupiter's fourth-largest moon. One concept that may be gaining traction is a so-called "clipper" probe that would make multiple flybys of the moon, studying its icy shell and suspected subsurface ocean as it zooms past.

"We briefed [NASA] headquarters on Monday, and they responded very positively," mission proponent David Senske, of NASA's Jet Propulsion Laboratory in Pasadena, Calif., said here Dec. 7 at the annual fall meeting of the American Geophysical Union.

http://www.space.com/18901-nasa-mission-jupiter-moon-europa.html
« Last Edit: 12/14/2012 02:12 PM by Star One »

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #56 on: 12/20/2012 07:57 PM »
The Europa de-scope final report studies have been finished. Unfortunately, the flyby and lander volumes are 23 megs apiece, which makes them too big to post here.

Here's the intro.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #57 on: 12/20/2012 07:58 PM »
Here's the orbiter study. Note that the orbiter is no longer the preferred option. You can get the best science-cost ratio out of the flyby mission.

None of the three studies mentions the SLS at all. It's not a preferred way to accomplish any of these missions.

Offline butters

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Re: Proposed Europa Missions
« Reply #58 on: 12/20/2012 08:05 PM »
The chronic mechanical problems plaguing the scientists drilling that frozen lake in Antarctica don't bode well for the classical sci-fi notion of drilling the ice sheet on Europa. That kind of mission seems to be well beyond our near-term capabilities.

Offline Blackstar

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Re: Proposed Europa Missions
« Reply #59 on: 12/20/2012 08:26 PM »
The chronic mechanical problems plaguing the scientists drilling that frozen lake in Antarctica don't bode well for the classical sci-fi notion of drilling the ice sheet on Europa. That kind of mission seems to be well beyond our near-term capabilities.

This is from the lander study:

"Over time, the composition of the surface ice
is modified by fragmenting and sputtering
larger molecules, and by emplacement of ions
from space such as sulfur (Carlson et al. 2009).
Thus, samples acquired from the very surface
will not compositionally represent the ocean.
Depending on the type and geographic location,
this radiation damage is expected to reach
depths of several centimeters (Patterson et al.
2012), and obtaining samples from as deep as
10 cm becomes necessary. Additionally, obtaining
a near-surface sample (from 0.52 cm
depth) and a deeper sample (510 cm depth)
would provide an in situ assessment of the
effects of radiation on ice composition. Therefore,
the recommended strategy is to drill into
the surface up to a depth of 10 cm, obtaining
samples from at least two different depths."


So not a very deep drill.