Author Topic: Europa and Enceladus  (Read 12122 times)

Offline Gravity Ray

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Europa and Enceladus
« on: 07/02/2008 12:20 am »
A flight of fancy perhaps:

How far along do we need to be before a serious sortie can be made to either Europa or Enceladus? I am thinking of a rather large capable robot on par with MSL.

What are some of the capabilities that you would like to see for the first submarine robot?

I think it should be a free floater and not be tied in to its surface lander. It should be capable of autonomous thought to gather data and then maybe come back up to the lander and send data back.

It will have to have a power source as powerful as possible, probably  nuclear.

It should have an 'arm', two, and some camera power (just incase something goes swimming by).

What else?

Offline khallow

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Re: Europa and Enceladus
« Reply #1 on: 07/02/2008 02:28 am »
Actually I disagree on the first submarine robot being free floating. There's no way, unless humans are nearby or we make some remarkable advances in AI (that we allow for this probe), that we can control such a robot. My take is that it'll be a drill that will pull up some fluid for analysis. We can fit some sort of sonar and hydrophones on the far end. Drilling at multiple locations and installing similar devices would allow us to map the sea floor in a region.
Karl Hallowell

Offline toddbronco2

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Re: Europa and Enceladus
« Reply #2 on: 07/02/2008 03:18 am »
You also cannot dismiss the difficulty of getting a very large spacecraft to make a controlled landing on Enceladus.  It's something that's really easy to ignore, but it's implications are huge.  entering into orbit around Saturn is not easy and takes an enormous delta V to accomplish.  Even then, your enormous orbit doesn't do much good for getting to Enceladus until you bleed of an amazing amount of orbital energy.  Mark my word that any mission to Enceladus is going to spend the better part of a decade just flying by saturnian moons or burning a low thrust engine just to get to the point where attempting a landing on Enceladus might even be possible.  Only after one of the more impressive orbital tours that NASA has ever attempted would you even be able to think about beginning your Enceladus landing phase.  Huygens was plenty challenging but was a veritable walk in the park compared to the challenges of an Enceladus lander.

This is one of the issues I have with the Google Lunar X Prize teams.  Many of them are focusing on the lunar rover while ignoring how they're going to get their lunar rover to the moon.  Some of the greatest challenges for lander missions occur long before the landings. 

Offline I14R10

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Re: Europa and Enceladus
« Reply #3 on: 07/02/2008 01:27 pm »
If we are going to use a submarine, entire spacecraft should have nuclear power source, because you first must melt all that ice underneath a lander.
And Europa/Enceladus lander should be full of various instruments, (like Kaguya - about ten different scientific instruments on one spacecraft).
And we could send orbiter together with lander

Offline Blackstar

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Re: Europa and Enceladus
« Reply #4 on: 07/02/2008 03:03 pm »
Actually I disagree on the first submarine robot being free floating. There's no way, unless humans are nearby or we make some remarkable advances in AI (that we allow for this probe), that we can control such a robot.

What's the time delay to Jupiter?

Offline Blackstar

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Re: Europa and Enceladus
« Reply #5 on: 07/02/2008 03:06 pm »
How far along do we need to be before a serious sortie can be made to either Europa or Enceladus? I am thinking of a rather large capable robot on par with MSL.

Right now the plans for Europa would be an orbiter, possibly launched around 2020 or so (assuming that NASA selects Europa and not Titan for the next outer planets mission).  If NASA decides to do a lander, it would not be until the 2030s, and I doubt it would include a submarine at that time.  This is a VERY difficult mission to accomplish.  The technology will probably not be ready for 50+ years, if that.

And keep in mind that Europa is a hellish place to operate.  Get a portable radio.  Turn it on.  Put it in your microwave oven at high power.  See how long it operates.  That's Jupiter's radiation.

Offline Gravity Ray

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Re: Europa and Enceladus
« Reply #6 on: 07/02/2008 05:33 pm »
Thanks for the feedback. Here is what I know that is actually being planned:

Sometime before the end of this year, probably November, NASA, and ESA will pick the finalist for the outer planet flag ship mission. As stated by blackstar it will be either Europa or Titan.

The Europa-Jupiter mission involves two orbiters with instruments designed to operate in the severe radiation environment of Jupiter. In addition to ESA and NASA, Russia also has expressed interest in the mission, proposing a Europa lander.

The Titan-Saturn flagship entails a main spacecraft that would orbit Saturn and deployment of secondary spacecraft to the surface of Titan. For the secondary spacecraft, there are proposals that would include elements such as a balloon for exploring the atmosphere, surface probes and even a mini-submarine for exploring lakes on Titan.

NASA only has 2.1 billion to spend on this (and thats it).

NASA and ESA will both down-select to one outer planet mission this fall. The mission to the outer planet would be launched via an Atlas 5, a Delta 4 Heavy or an Ares V no later than 2017. The launch would be designed to send the spacecraft on a lengthy cruise toward its destination but one that would be no longer than seven years. So we should see actual stuff happening around 2024.

the outer planet flagship would make use of Multi-Mission Radioisotope Thermoelectric Generators for power using plutonium-238.

I really do think that Europa seems like a much more interesting target than Titan to me. The idea of a robot in an ocean is much to tempting for me to pass up. Although a ballon robot in Titan also raises my interest. Basically any robot on another planet gets my space jucies flowing.

However, this post was more a flight of fancy... What you want to see, etc... I agree that landing a robot on Europa is going to be difficult, but hey those are the fun missions. I think the MSL is going to give terrific feedback and great lessons for these robots to the outer planets. Can't wait for that...

Offline Blackstar

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Re: Europa and Enceladus
« Reply #7 on: 07/02/2008 06:53 pm »
Sometime before the end of this year, probably November, NASA, and ESA will pick the finalist for the outer planet flag ship mission. As stated by blackstar it will be either Europa or Titan.

Actually, that's now delayed. No decision is likely this year.  In fact, I would hazard a guess that it will be at least another year for a decision.  Some info here:

http://www.livescience.com/blogs/2008/06/27/nasas-space-science-program-funding-fallout/

"Tight budgets may well mean slipping an outer planet flagship mission to Jupiter or Saturn beyond 2016 to perhaps 2020. Some good news is that such a mission may get a financial boost from $2.1 billion to $3 billion."

You can find the status of the outer planets flagship studies here:

http://www.lpi.usra.edu/pss/presentations/200806/04niebur.pdf
« Last Edit: 07/03/2008 12:47 am by Blackstar »

Offline iamlucky13

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Re: Europa and Enceladus
« Reply #8 on: 07/02/2008 10:56 pm »
A lander on either one of those bodies is technically feasible now (a submarine I'm not so sure about), but for $2 billion it would have to be pretty small. Unlike Mars, neither Europa or Enceladus have atmospheres to help slow a lander, and although their mass is small, you also have a significant portion of the escape velocity of Jupiter or Saturn to account for. It certainly wouldn't be anything like MSL. Phoenix or perhaps an MER-sized payload might be possible. I don't know.

As far as a submarine, that's quite a bit more ambitious. I don't think wireless is remotely possible. It would need to transmit through several miles of ice to a repeater station. A tether could be used, but the energy required to drill through that much ice and displace the chips towards the surface would be prohibitive. A sub that could melt its way through the ice would risk losing it's tether as the hole refreezes around it. It also raises some planetary protection concerns. However, I think NASA or perhaps USGS was looking at testing a similar concept in Lake Vostok under Antarctica.

Any mission to the surface of any of the outer moons will be RTG powered.

Personally, I think a Titan mission has the greatest odds. Hguyens was a pretty powerful teaser, and an RTG-powered hot-air balloon could potentially map large areas of the surface, and maybe deploy a couple very small soil probes similar to the failed Deep Space 2 mission that piggybacked on Mars Polar Lander.

Offline khallow

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Re: Europa and Enceladus
« Reply #9 on: 07/03/2008 02:34 am »
Actually I disagree on the first submarine robot being free floating. There's no way, unless humans are nearby or we make some remarkable advances in AI (that we allow for this probe), that we can control such a robot.

What's the time delay to Jupiter?

A bit over an hour round trip at closest distance. Having said that, I changed my mind. A weighted probe that just drops at a controlled rate is a feasible submarine probe. No need for short term feedback from Earth with that sort of design. You need something that can communicate through that much water and ice though. Maybe use an extremely low frequency system like the ones on Earth. That greatly limits data, but allows you to communicate through a lot of stuff. A lot depends on the salinity of the water (if liquid water exists, apparently it's not yet certain) and the thickness of the ice.
Karl Hallowell

Offline Blackstar

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Re: Europa and Enceladus
« Reply #10 on: 07/03/2008 04:06 am »
A bit over an hour round trip at closest distance. Having said that, I changed my mind. A weighted probe that just drops at a controlled rate is a feasible submarine probe. No need for short term feedback from Earth with that sort of design. You need something that can communicate through that much water and ice though. Maybe use an extremely low frequency system like the ones on Earth. That greatly limits data, but allows you to communicate through a lot of stuff. A lot depends on the salinity of the water (if liquid water exists, apparently it's not yet certain) and the thickness of the ice.


My first question was to point out that we don't have real-time communication.  If you send a probe, it's going to have to be able to operate on its own for long periods.

As for a submarine probe, nobody should underestimate the difficulty of this.  We have not even done it on Earth yet.  There are so many obstacles to overcome it's mind-boggling.  My own guess is that we won't do something like this for 80-100 years.

Offline Antares

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Re: Europa and Enceladus
« Reply #11 on: 07/03/2008 05:20 am »
Here's a completely uninformed but creative question: if the radiation environment around Jupiter is so harsh, is there a system analogous to a solar panel that could harness the energy for electrical power, be it incident radiation or simply passing through the field?
If I like something on NSF, it's probably because I know it to be accurate.  Every once in a while, it's just something I agree with.  Facts generally receive the former.

Offline simonbp

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Re: Europa and Enceladus
« Reply #12 on: 07/03/2008 04:08 pm »
Here's a completely uninformed but creative question: if the radiation environment around Jupiter is so harsh, is there a system analogous to a solar panel that could harness the energy for electrical power, be it incident radiation or simply passing through the field?

Not really; the radiation flux is too low to effectively heat anything, but too high energy to work with photovoltaics. A magnetic tether would be a pretty effective method of propulsion in Jovian space, but would still need an intrinsic power source...

WRT a Europa submarine, the real issue is in getting the submarine through the ice and communicating with it. Current estimates of on the depth of the surface ice layer vary from ~1-10 km, meaning the thinnest possible point you'd expect is ~500 m. So, you'd need to land a lander on the surface, right at a weak point, drill though half a kilometer of ice at around 100 K, and then lower on a winch a small microsub. Even then, the microsub would only probably have a camera and a sample collection device; once a few "interesting" things have been collected, the sub can be winched back up to the lander and the samples chemically analysed...

An Enceladus sub is even less likely, as any liquid water in its interior is probably mixed in a briny slush tens of kilometers down...

Simon ;)
« Last Edit: 07/03/2008 04:11 pm by simonbp »

Offline khallow

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Re: Europa and Enceladus
« Reply #13 on: 07/03/2008 05:52 pm »
A bit over an hour round trip at closest distance. Having said that, I changed my mind. A weighted probe that just drops at a controlled rate is a feasible submarine probe. No need for short term feedback from Earth with that sort of design. You need something that can communicate through that much water and ice though. Maybe use an extremely low frequency system like the ones on Earth. That greatly limits data, but allows you to communicate through a lot of stuff. A lot depends on the salinity of the water (if liquid water exists, apparently it's not yet certain) and the thickness of the ice.


My first question was to point out that we don't have real-time communication.  If you send a probe, it's going to have to be able to operate on its own for long periods.

As for a submarine probe, nobody should underestimate the difficulty of this.  We have not even done it on Earth yet.  There are so many obstacles to overcome it's mind-boggling.  My own guess is that we won't do something like this for 80-100 years.

And by that point, we'll probably be running manned (or superduper AI) expeditions to these places anyway.
Karl Hallowell

Offline Blackstar

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Re: Europa and Enceladus
« Reply #14 on: 07/03/2008 07:59 pm »
And by that point, we'll probably be running manned (or superduper AI) expeditions to these places anyway.

You have a much more optimistic view of progress in space exploration than I do.  I don't expect a human mission to Mars for another 50 years at least.  As for sending humans to Jupiter?  They'd fry.

Offline Blackstar

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Re: Europa and Enceladus
« Reply #15 on: 07/03/2008 08:02 pm »
Even then, the microsub would only probably have a camera and a sample collection device; once a few "interesting" things have been collected, the sub can be winched back up to the lander and the samples chemically analysed...

I don't see how you get down that deep and then bring a sample back up.  Remember that the hole freezes above you.

One of the concepts for a cryobot is that it drops small hockey puck like relay transmitters as it melts its way through the ice.  These become embedded and relay weak signals back up.

All this stuff would have to be tested on Earth first.  Then I'd think that a good place to follow on test would be the Mars northern pole.  But this is expensive science.  You need a nuclear reactor, and the price range for those start at $5 billion and up.

Offline khallow

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Re: Europa and Enceladus
« Reply #16 on: 07/04/2008 12:00 am »
And by that point, we'll probably be running manned (or superduper AI) expeditions to these places anyway.

You have a much more optimistic view of progress in space exploration than I do.  I don't expect a human mission to Mars for another 50 years at least.  As for sending humans to Jupiter?  They'd fry.

80-100 years is a long time. If someone sends people to Mars in 50 years, they still have 30-50 years to figure out the vagaries of a Jupiter expedition.
Karl Hallowell

Offline Phillip Huggan

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Re: Europa and Enceladus
« Reply #17 on: 07/04/2008 12:19 am »
One of the concepts for a cryobot is that it drops small hockey puck like relay transmitters as it melts its way through the ice.  These become embedded and relay weak signals back up.

How about this: you land a lander on the surface at the thinnest thickness of ice you can find.  Then you deploy a radioactive hockey puck that melts its way through the ice.  The hockey puck (can't be a baseball) is attached to a wire,  attached to the lander.  The hockey puck drops through the ice (and maybe slush) and splashes into the water.  The puck itself would be the sensor suite.  It would contain the needed bioreactor-type sensors (don't ask me what those are) to look for amino acids and microbes.
If the CNT wire or whatever was spooled to the lander, refreezing would "hang" the puck.  Two ways around this are to make the tether itself radioactive, or more likely, to include the spool on top of the puck sensor suite.  Whatever scientific expermients are performed sub-ice in the water, could be relayed up the wire/thread to the lander for transmission to Earth.
« Last Edit: 07/04/2008 12:22 am by Phillip Huggan »

Offline Blackstar

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Re: Europa and Enceladus
« Reply #18 on: 07/04/2008 12:58 am »
How about this: you land a lander on the surface at the thinnest thickness of ice you can find.  Then you deploy a radioactive hockey puck that melts its way through the ice.

Are you a nuclear engineer?  What material do you propose to make this out of?

Offline Blackstar

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Re: Europa and Enceladus
« Reply #19 on: 07/04/2008 01:02 am »
80-100 years is a long time. If someone sends people to Mars in 50 years, they still have 30-50 years to figure out the vagaries of a Jupiter expedition.

I tend to think of these things in multiples of decades.  In 2004 Bush announced plans to put humans on the Moon "no later than 2020."  Well, 2020 will be roughly fifty years since the first Moon landing.  So, in those fifty years, how much forward progress will we have made?--we will have returned to the starting line.  So who's to say it won't take another fifty years after the first Mars landings just... to get back to Mars?

Offline Phillip Huggan

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Re: Europa and Enceladus
« Reply #20 on: 07/04/2008 01:17 am »
How about this: you land a lander on the surface at the thinnest thickness of ice you can find.  Then you deploy a radioactive hockey puck that melts its way through the ice.

Are you a nuclear engineer?  What material do you propose to make this out of?

I'm not a nuclear engineer but the knowledge plutonium is hot enough to melt ice isn't that esoteric.  Turns out the idea isn't original.  Googling, radioactive melt through ice, yields this ESA plan I hope they follow through with: http://people.web.psi.ch/gassmann/herbstschule/2005/Eis.pdf
There is also this variation that could melt its way back up, though a powerful transmitter from the water is simpler: http://news.bbc.co.uk/2/hi/science/nature/3548139.stm
Using a hockey puck is a novelty.
« Last Edit: 07/04/2008 01:18 am by Phillip Huggan »

Offline I14R10

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Re: Europa and Enceladus
« Reply #21 on: 07/04/2008 07:39 am »
But what about channels on Europa? They must be pretty deep. If you land there, you would have a few hundred meters (I don't know exact depth of these channels) less to melt.

Offline khallow

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Re: Europa and Enceladus
« Reply #22 on: 07/04/2008 08:07 am »
80-100 years is a long time. If someone sends people to Mars in 50 years, they still have 30-50 years to figure out the vagaries of a Jupiter expedition.

I tend to think of these things in multiples of decades.  In 2004 Bush announced plans to put humans on the Moon "no later than 2020."  Well, 2020 will be roughly fifty years since the first Moon landing.  So, in those fifty years, how much forward progress will we have made?--we will have returned to the starting line.  So who's to say it won't take another fifty years after the first Mars landings just... to get back to Mars?

I forgot also that I was considering only what I consider the most likely scenario. We could also have a dark age, a technological setback due to a bad global government system, some sort of economic or environmental disaster, large scale nuclear war, global scale natural disaster, etc. Under such circumstances, abandoning space travel for centuries or longer could be a consequence. There's even a small chance of species extinction in my humble opinion.

But I see more likely a scenario where space development is fueled more by private enterprise than government investment. That includes significant space tourism and development of some private industrial and transportation infrastructure in space. In such a situation, I think manned expeditions to other planets is feasible over the course of a number of decades.
« Last Edit: 07/04/2008 08:09 am by khallow »
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Offline Mogster

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Re: Europa and Enceladus
« Reply #23 on: 07/05/2008 01:30 pm »
The best bet for the next flagship mission is a Huygens follow up, a Titan lander with a long lasting baloon floating in the thick atmosphere. The technologys available now and from the glimps we've had so far Titan looks to be the most dyamic terrestrial body in the solar system after Earth.

Europa's a fascinating place but for a lander the really interesting stuff requires melting a submarine through possibly many meters of ice then transmitting data back through that same ice. Its simple to talk about but the technology doesn't exist to even come close to doing this on Earth autonomously, never mind on Europa. I don't think anyone alive today will see this sort of mission to Europa.
« Last Edit: 07/05/2008 01:31 pm by Mogster »

Offline Phillip Huggan

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Re: Europa and Enceladus
« Reply #24 on: 07/05/2008 06:34 pm »
I14R10, the problem NASA has with those channels is that they are unstable and thus represent a high-risk mission.  They are caused by shearing gravity forces of the gas giant planets.  I guess you could land near them and relaunch a low-altitude probe towards them if the drilling plan is unfeasible.  IDK how small transmitters will get, but if they are small enough to transmit to an orbiting spacecraft, maybe some floating golfball sized labs could be dumped into an expanding crevice if the payload of balls could be slowed enough by retrorockets.  Most of the balls would probably be broken or lost under ice, but if one of them could admit some water and scan for amino acids, and resurface briefly to transmit, the mission would have enormous scientific value.  Enough golfballs with enough durability could see them churn under ice for years, occasionally popping out through a crevice to radio an orbitting spacecraft.

Mogster, Europa missions don't have to be the hardest difficulty submarine blueprint.  Smashing a impactor into the ice and looking for organic traces would provide some proof-of-life value.  Geysers that spew ice originating from the water "interior", may provide frsh traces of life.
The nice thing is the missions don't appear to be either-or.  You can cram a few missions on each craft.  Two to Titan, three to Enceladus, whatever.  The Titan mission is a relatively safer look for some low-level value scientific data.  Titan most resembles Earth, but no liquid water (maybe someone from NASA should tell the present administration it rains oil on Titan?).  The ice Moons are lottery tickets for life.  I'd be worried about polluting Ice Moons with microbes accidentally.
« Last Edit: 07/05/2008 11:25 pm by Phillip Huggan »

Offline khallow

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Re: Europa and Enceladus
« Reply #25 on: 07/05/2008 11:31 pm »
The potentially delicate nature of the targets complicates missions to explore them. Even if you manage to eliminate all possibility of biological contamination (addressing Phillip's concern above), we'll still have to be rather careful. If there is life on Europa, it might be sensitive to radiation or the possible nuclear fuel for a mission.

For example, if there is water breathing multicelled organisms in one of these places, they may be as sensitive to plutonium poisoning as we supposedly are to airborn plutonium. Then any plutonium power source would either have to be removed or designed so that compromise of the system isn't likely within a certain number of half lives of the fuel. We'll have to consider possible problems with heavy metals and some persistent manmade materials like fiberglass or nanoparticles.
« Last Edit: 07/05/2008 11:31 pm by khallow »
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Offline Blackstar

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Re: Europa and Enceladus
« Reply #26 on: 07/06/2008 02:09 am »
The best bet for the next flagship mission is a Huygens follow up, a Titan lander with a long lasting baloon floating in the thick atmosphere. The technologys available now and from the glimps we've had so far Titan looks to be the most dyamic terrestrial body in the solar system after Earth.

Europa's a fascinating place but for a lander the really interesting stuff requires melting a submarine through possibly many meters of ice then transmitting data back through that same ice.

You cannot really argue that "the technology is available now" for a Titan balloon because it has not been proven.  Nobody has inflated a balloon on another planet.  Even the people studying this mission refer to the balloon as essentially a Pathfinder class mission, more technology development than science.

The Titan mission proposal right now is for an orbiter, lander and balloon.  The three vehicles actually gives them what are called good "descope options," meaning that they can eliminate costs in big chunks, first by getting rid of the balloon, then the lander.  They've determined that simply going with an orbiter would put them below the minimum science threshold, however.

I think an interesting question will be if they can do any interesting science at Enceladus with the orbiter before it goes into Titan orbit.  Enceladus got a lot more interesting after the discovery of organics.  But doing in situ science at Enceladus is not viable at this time.

You can find a status briefing on the outer planets flagship studies here:

http://www.lpi.usra.edu/pss/agenda/200806/index.shtml

However, the policy situation is fluid, and NASA is going to seek help in downselecting from the two proposals to one.

As for Europa, nobody is talking about a lander anytime soon.  The initial goal would be an orbiter that would do Jupiter science for a couple of years before settling in at Europa for up to a year.  Only after the orbiter returns its data would anybody decide if a lander is worthwhile.  In some ways that's an argument against Europa, because we know that we can do a lander at Titan already, so it's possible to get into the soup at Titan and do stuff.  It's just that nobody believes that it's possible to find life on Titan, whereas they're not sure about Europa.

Offline Blackstar

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Re: Europa and Enceladus
« Reply #27 on: 07/06/2008 02:14 am »
For example, if there is water breathing multicelled organisms in one of these places, they may be as sensitive to plutonium poisoning as we supposedly are to airborn plutonium. Then any plutonium power source would either have to be removed or designed so that compromise of the system isn't likely within a certain number of half lives of the fuel. We'll have to consider possible problems with heavy metals and some persistent manmade materials like fiberglass or nanoparticles.

Right now the plan for the Europa orbiter is that it crashes on Europa.  The requirement for planetary protection of Europa was established by the NRC in a 2000 report:

http://www.nap.edu/openbook.php?record_id=9895&page=22

"The task group therefore recommends the following standard: for every mission to Europa, the probability of contaminating a europan ocean with a viable terrestrial organism at any time in the future should be less than 10-4 per mission. This standard calls for explicit calculation of the probability of contamination posed by each particular mission. It allows spacecraft designers to take advantage of the bioload reduction that occurs from radiation in the jovian environment (see Chapter 2). The value of 10-4 was chosen because of its historical precedents in the planetary protection resolutions issued by COSPAR."

[a suggested formula for calculating the probability of contamination is contained in the report's appendix at: http://www.nap.edu/openbook.php?record_id=9895&page=29#p200033c7ddd0000043 ]

Presumably the Europa orbiter designers believe that they can get their spacecraft to the desired 10-4 probability of contamination.


Offline Phillip Huggan

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Re: Europa and Enceladus
« Reply #28 on: 07/06/2008 02:57 am »
As for Europa, nobody is talking about a lander anytime soon.  The initial goal would be an orbiter that would do Jupiter science for a couple of years before settling in at Europa for up to a year.  Only after the orbiter returns its data would anybody decide if a lander is worthwhile.  In some ways that's an argument against Europa, because we know that we can do a lander at Titan already, so it's possible to get into the soup at Titan and do stuff.  It's just that nobody believes that it's possible to find life on Titan, whereas they're not sure about Europa.

That's what I thought until I read this an hour ago:  http://www.esa.int/esaCP/SEM52QQ03EF_Expanding_0.html
I'm not bullish about non-carbon based life.  Probably computer simulations in the future will show just how much more verasatile carbon is to form a metabolism than is, silicon or whatever else.  But if there is an ocean 100km below Titan's ice and "lithosphere", that upgrades Titan as a potential active ecosystem in my books ahead of Callisto and Ganymede, and behind only Enceladus (likely water and known organics) and Europa (likely water and likely/maybe organics).  It's still easier to get to Europa's water because its ice shell is thinner than Enceladus.  Titan would be even harder with 100km "soil" and ice to penetrate.
The wiki says you can fly on Titan; it is destined to become the number #1 tourist destination in the Solar System one day.

Offline jmjawors

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Re: Europa and Enceladus
« Reply #29 on: 07/06/2008 03:52 am »
Wait a second, let's keep this discussion honest.  The force driving the internal heating within both Europa and Enceladus are likely the same (tidal), but the ground truth (or, underground truth?) about these two moons is different.  On Europa there is likely to be a global ocean with an icy shell, while on Enceladus we see a very localized grouping of geyser-like activity.  Nobody knows what is going on just under the surface there, but it does not appear to be the global ocean that Europa has.  So before we start comparing ice shells and the like, let's remember that we don't yet know enough to talk in those terms -- especially about Enceladus.  But we do know that with Europa we're likely dealing with a global phenomenon and on Enceladus it appears to be a very localized one.

Anyway, some of you guys may be interested in these.  JPL hosts a monthly lecture series and they keep an archive online.  I never miss them.  Here are three relevant ones:

Enceladus: The Newest Wrinkle from Saturn's Tiger-Striped Moon
Europa's Underground Ocean
Saturn's Moon Enceladus : A Small, Cold Moon with a Warm Spot -- (older)
.:: Matt ::.

Offline Kaputnik

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Re: Europa and Enceladus
« Reply #30 on: 07/06/2008 02:34 pm »
Nobody has inflated a balloon on another planet.

Erm, except for the Soviets on Venus in the 80s.
"I don't care what anything was DESIGNED to do, I care about what it CAN do"- Gene Kranz

Offline Blackstar

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Re: Europa and Enceladus
« Reply #31 on: 07/06/2008 09:59 pm »
Nobody has inflated a balloon on another planet.

Erm, except for the Soviets on Venus in the 80s.

Well, yeah, but that doesn't really count.  Decades ago and by a group that's not us (plus: different planet) means that we don't know how to do it and have to start from scratch.

Offline gospacex

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Re: Europa and Enceladus
« Reply #32 on: 07/06/2008 11:24 pm »
Nobody has inflated a balloon on another planet.
Erm, except for the Soviets on Venus in the 80s.

Well, yeah, but that doesn't really count.  Decades ago and by a group that's not us (plus: different planet) means that we don't know how to do it and have to start from scratch.

It doesn't hurt to ask for information. After all, a lot of NASA information is freely available to everybody, including Russians.

Offline Blackstar

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Re: Europa and Enceladus
« Reply #33 on: 07/07/2008 12:40 am »
It doesn't hurt to ask for information. After all, a lot of NASA information is freely available to everybody, including Russians.

There are, in fact, Russian scientists who support American space programs.  Lots more Russians working with the Europeans, actually.

But look up ITAR sometime.

Offline gospacex

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Re: Europa and Enceladus
« Reply #34 on: 07/07/2008 04:38 am »
It doesn't hurt to ask for information. After all, a lot of NASA information is freely available to everybody, including Russians.
There are, in fact, Russian scientists who support American space programs.  Lots more Russians working with the Europeans, actually.

But look up ITAR sometime.

ITAR prohibits asking questions?!

Offline A_M_Swallow

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Re: Europa and Enceladus
« Reply #35 on: 07/07/2008 04:44 am »
ITAR prohibits asking questions?!

It certainly stops people from answering detailed questions.

Offline Analyst

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Re: Europa and Enceladus
« Reply #36 on: 07/07/2008 07:21 am »
ITAR prohibits asking questions?!

It certainly stops people from answering detailed questions.

Talk about shooting into your foot. You are working a problem and know someone other has already solved it, but asking him would reveal you are working the problem and have encountered a specific hard stop, which he, who already solved it, is not allowed to know about. So you spend money and time to invent the wheel again - or get cancelled before.

Helps national security a lot. Stems from paranoia. There I prefer the Europeans working with the Russians.

Analyst

PS: Read about the Canadians and their ITAR problems working for the Phoenix Mars lander (MET station). Something funny if not so sad.

Offline Mogster

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Re: Europa and Enceladus
« Reply #37 on: 07/07/2008 10:50 am »
The Titan mission is a relatively safer look for some low-level value scientific data.  Titan most resembles Earth, but no liquid water (maybe someone from NASA should tell the present administration it rains oil on Titan?).  The ice Moons are lottery tickets for life.  I'd be worried about polluting Ice Moons with microbes accidentally.

I wouldn't call a low level aerial recon and atmospheric sampling of a world as dynamic as Titan of low level scientific value, especially as we know so little about it. The clouds do make it tough to photo recon from orbit. From a PR point of view the pics would probably look very impressive in the papers as well.

I also think we need to back away from every planetary mission being a "search for life" or being viewed as having lower scientific value. I tend to think that anything short of a meeting with intelligent aliens would slip from the pages and screens of the media rapidley anyway :)
« Last Edit: 07/07/2008 10:50 am by Mogster »

Offline gospacex

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Re: Europa and Enceladus
« Reply #38 on: 07/07/2008 11:39 am »
ITAR prohibits asking questions?!

It certainly stops people from answering detailed questions.

I see. I wasn't clear. I meant "NASA can ask Russians about their Venusian balloon (design etc)", not vice versa.

Offline Kaputnik

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Re: Europa and Enceladus
« Reply #39 on: 07/07/2008 01:33 pm »
Nobody has inflated a balloon on another planet.

Erm, except for the Soviets on Venus in the 80s.

Well, yeah, but that doesn't really count.  Decades ago and by a group that's not us (plus: different planet) means that we don't know how to do it and have to start from scratch.

Sorry I took 'nobody' at face value, I didn't interpret is as meaning 'NASA'.
If nothing else it suggests that such a task is not all that difficult. The Russian planetary science program was always decades behind NASA's anyway; I doubt that they could pull off a Viking-type mission even today.
IMHO, Titan would represent a particularly easy atmospheric entry: low gravity, thick atmosphere, low toxicity and temperatures could make it an easier target than an Earth entry, and certainly much, much easier than Mars.
The challenge presented by a Titan balloon is on a completely different order to that of any Europa or Enceladus lander.
"I don't care what anything was DESIGNED to do, I care about what it CAN do"- Gene Kranz

Tags: Space Oceans 
 

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