Further evidence for subsurface liquid ocean on Enceladus.

[RGClark]

NASA page showing a model of the plumes that connects a vent at the surface to an ocean below:

"This graphic shows how the ice particles and water vapor observed spewing from geysers on Saturn's moon Enceladus may be related to liquid water beneath the surface. The large number of ice particles and the rate at which they are produced require high temperatures, close to the melting point of water. These warm temperatures indicate that there may be an internal lake of liquid water at or near the moon's south pole, where the geysers are present."
http://www.nasa.gov/mission_pages/cassini/multimedia/cassini20080207.html

In this model the temperatures don't have to be particularly high. Just near the melting point.

Bob Clark

 

[RisingFury]

That's about 1.21 gigawatts each.

 

[steph]

Maybe you could crash something large onto the surface, or blow something up, and measure siesmic shock waves from various points to build a model of the interior. I think that's what they did with the moon; crashed S-IVB stages into it and measured the response from sensors placed on the surface.

And the alien civilization living under the ice will think we've commenced orbital bombing :lol:

 

[fsci123]

And the alien civilization living under the ice will think we've commenced orbital bombing :lol:

Yeah but they'll be too slow to react anyway:lol:

 

[kamaz]

Below is a fragment of a larger story I was working on several months ago. If you like it, say thanks -- I may get enough motivation to finish this thing

- Let us summarize findings… Your team first?
- As far as our team is concerned, there’s nothing. We’ve put the seismometers in place, we’re picking up some distant icequakes – but nothing moves around here. Except for us.
- It may be that they have not arrived yet.
- If they are not here, why don’t we just set some charges and do a scan?
- We know they’ve had seismic stations on the surface. They may still work… We don’t want to tell them that we’re here, don’t we?
- Well, after Sh’Ra…
- That was a generation ago. We cannot presuppose what they think now… Okay, second group… T’Hea, will you report?
- With pleasure, sir. We took my mother’s maps and we have went around the caves. It appears that the caves have changed… but not much. The maps are still good.
- You’ve been to your mother’s cave?
- Yes, we went there… There’s nothing.
- Strange…
- Not really, given what else we have found.
- Which is what?
- A drilled tunnel, sir.
- To where?
An image of the caves came up on the projector.
- We started with this cave here – it is a large cave near the bottom of the complex, which makes it a suitable location for a base. So we went there. Almost immediately, we have discovered a drilled shaft going up. We went up the shaft – it leads to another cave above it, but we were unable to enter it. It is filled with gas… mostly nitrogen, with about 20% oxygen.
Someone attempted a joke:
- Looks like they like to party!
The old professor felt a need to comment.
- Yes, yes… I know students have nothing against being permanently intoxicated, but, before we start making lists of people willing to explore that cave… what else do we know?
T’Hea continued.
- Unfortunately, we cannot do a scan, but if we look at my mother’s map, then this cave here – it had no connection to the Ocean in her time. It was isolated. So it is logical, that the aliens have drilled to it from the surface, then moved their drilling equipment into the cave and drilled again…
Someone asked:
- Why go through this trouble?
Before T’Hea could answer a guy from the end of the room spoke.
- That’s easy, because it allows them to stage their operation… It seems that they breathe this gas mixture. So in the first stage, they drill down from the surface to an isolated cave, and fill it with gas, so they can live there. Then they drill for a second time, this time all the way down to the Ocean.
A female student raised her doubts:
- But where are they now?
- What do you mean?
- If they have drilled all the way, it means that they must be here, right? So, where are they?
The leader of the seismic team spoke:
- They are not there now. We have very sensitive equipment… We would know.
- There are two options then. One: they are already in the Ocean – in such case, it will be difficult to find them. Two: they have already been in the Ocean, and came back. In either case, we will not see them.
- But, that means we could enter the cave… They could leave something…
A storm of comments erupted.
- Dangerous…!
- … great chance…
- Stupid…
- But… empty… not… there…
- If… traps…
The old professor interrupted the discussion.
- If may say something… Thanks. My proposal is that we simply sit and wait.
The students opposed.
- Must act…
- …chance…
- …boring…
He silenced them again.
- Yes, yes. I understand that you want to be the first ones to see an alien, but listen to the old bore… In the past, aliens would appear at very regular intervals. Let’s say that there is some regular mechanism at work… some… opportunity. I can tell you that the tunnel we’ve found has not been made during this opportunity.
- How so?
- You should know, as students of geophysics, that drilling such tunnel takes time… And there was not enough time now, because the current opportunity is just starting – in fact, we’ve arrived here just when it began. So the tunnel must have been made during the previous opportunity – or even earlier than that.
The female student had doubts again:
- But that means they came during the previous opportunity… and already left!
- That could be, yes. But remember – a generation ago they would come regularly. Then they stopped… but we have also stopped looking. We now know that they have built a base when we were not looking. If they are still coming regularly – they should appear just about know. So just wait and see… Our seismometers will pick them up if they appear. And – we will put watch just outside the cave.
One student raised a question:
- What if they don’t arrive? We’ll waste the whole vacation time!
- Okay. I will bet a bottle of helium. Deal?
The student realized that such a tangible benefit would be actually preferred to meeting hypothetical aliens.
- Deal, sir!

 

[jedidia]

And the alien civilization living under the ice will think we've commenced orbital bombing

And they would think correctly...

 

[MattBaker]

And the alien civilization living under the ice will think we've commenced orbital bombing :lol:

Technically we did. Technically we are also an invasive species into their habitat.

 

[Unstung]

Since this thread has been revived, I want to clarify some things that I wrote because I was much stupider a few months ago.

The tiger stripes themselves don't connect to the ocean, they're tectonic fractures. Remote sensing of the ocean is much safer.

1. I was trying to make a distinction between the tiger stripes and the plumes. While the active jets are located within the fractures, the fractures encompass much more terrain. The existence of the fractures does not seem to depend on active jets, but geologic activity due to heating.

2. Remote sensing is safer and cheaper on an inexpensive mission (spectroscopy, imagery), but mass spectroscopy and a capture mission very much involve contact science. The former has been used on Cassini and both have the potential to detect life with little risk, but proposals the latter wants to kill any possible lifeforms before the sample reaches Earth to avoid using very expensive facilities.

Unfortunately, mass spectroscopy cannot detect advanced dolphins capable of building rockets but limited by their watery prison.

 

[steph]

Couldn't they detect and map out the ocean in a way similar to how they detect gravity variations on earth? A bit like the GOCE mission, relying on minute changes in the orbit to extrapolate some info about the underlying "geology" of the planet. Sure, it won't offer much, but some info about the ocean might be inferred from the data.
Also, if they decide to do a sample return and drill through the ice, couldn't they melt the ice somehow? As opposed to using mechanical drilling techniques like on earth. I suppose that at those low temperatures (assuming they won't drill in the fracture zones), the ice should be quite hard.
Any other planetoids closer to us which might be a nice training run for Enceladus? Perhaps Ceres?

Unfortunately, mass spectroscopy cannot detect advanced dolphins capable of building rockets but limited by their watery prison.

Would be really interesting to see how mythology and the perception of the Universe and their world would develop in such a species. Basically for all their evolution, they'd be encased, with possibly no knowledge of the Solar System etc. We've been staring at the sky since forever with our transparent atmosphere, but they'd only find out about it when/if they develop technology to either break out of the ice or some sort of remote sensing. Or perhaps the ice is thin enough in some areas to let some light from outside pass through. Perhaps in the fracture zones. Assuming the heat and tectonic movement doesn't kill any creature attempting to ascend.
Also, in such low/no light conditions, perhaps they wouldn't develop eyes to perceive visible light. Though if they can "sense" infrared , they might still see the stars. Or else, they might get onto the surface and have no idea of what lies above them.

 

[Unstung]

Couldn't they detect and map out the ocean in a way similar to how they detect gravity variations on earth? A bit like the GOCE mission, relying on minute changes in the orbit to extrapolate some info about the underlying "geology" of the planet. Sure, it won't offer much, but some info about the ocean might be inferred from the data.
Also, if they decide to do a sample return and drill through the ice, couldn't they melt the ice somehow? As opposed to using mechanical drilling techniques like on earth. I suppose that at those low temperatures (assuming they won't drill in the fracture zones), the ice should be quite hard.
Any other planetoids closer to us which might be a nice training run for Enceladus? Perhaps Ceres?

Radio antennas on Earth used the redshift (or Doppler shift) in Cassini's radio transmissions during flybys to estimate the size of Enceladus' ocean. Something similar has been done with GRACE at Earth and GRAIL at the moon, but GOCE did not rely on redshift. So the method GOCE uses has not been tested away from Earth, but it should work and provide accurate gravity maps. However, the massive fuel requirement to get any mission into orbit around Enceladus will be really limiting and not practical for any Saturn mission in the foreseeable future.

I'm not sure about the how GRACE and GOCE differ in scientific capability, but both should be able to map out an ocean due to the density difference between water in its liquid and solid state. Maybe gravity maps can also help understand geologic activity at Enceladus.

Melting the ice is possible, but even that will take a long time and the pressure will increase with depth. Radioisotope generators produce a lot of heat, so using Plutonium-238 to melt through ice has been suggested at Europa. Finding a safe landing site, high pressure, and avoiding any hazards in the ice shell while drilling are among the many issues with flying such a complex mission.

The sample return I mentioned is based on using aerogel to capture icy particles and return them like what has been done on the Stardust mission. A problem with that is ensuring enough geyser samples have been collected for some microbial life to be in the mix, not to mention contamination. Proposals include heating the samples or crashing them without a parachute on Earth to destroy any lifeforms so expensive biohazard facilities wouldn't have to be maintained for the mission. Thus, the proposals aren't really about detecting life. They're on a small Discovery budget after all and dealing with Planetary Protection is really expensive.

Any plumes on Ceres and Europa will only be confirmed through future missions, but thankfully Dawn will orbit Ceres next year. The aerogel technology has already been tested, so further tests aren't an issue. Drilling down using a melt probe cannot be done on Ceres, however, because any ice on the surface would sublimate. It's not far enough from the sun.

If a mission is going through the effort of drilling or collecting samples with aerogel (assuming there are plumes), Europa is more favorable due to being much closer to Earth and probably more favorable to life. Europa's ocean is known to be in contact with a mantle and thin crust where nutrients can be transferred, and getting plenty of energy through tidal heating which kept its ocean stable for billions of years. If a spacecraft has to orbit Europa, the more massive moon and three other Galilean satellites help reduce fuel consumption. Unfortunately Jupiter's magnetic field is strong at Europa and harmful to any spacecraft.

 

[RGClark]

NASA page showing a model of the plumes that connects a vent at the surface to an ocean below:

"This graphic shows how the ice particles and water vapor observed spewing from geysers on Saturn's moon Enceladus may be related to liquid water beneath the surface. The large number of ice particles and the rate at which they are produced require high temperatures, close to the melting point of water. These warm temperatures indicate that there may be an internal lake of liquid water at or near the moon's south pole, where the geysers are present."
http://www.nasa.gov/mission_pages/cassini/multimedia/cassini20080207.html

In this model the temperatures don't have to be particularly high. Just near the melting point.

JPL is investigating robots that can explore fissures in volcanos. They are also considering how they could be used to travel to the subsurface through fissures on worlds such as Europa and Enceladus:

News | January 7, 2015
NASA Robot Plunges Into Volcano to Explore Fissure.

http://www.jpl.nasa.gov/news/news.php?feature=4431

 

[TMac3000]

What are the odds of a manned mission to Enceladus by, oh say 2080?

 

[kamaz]

What are the odds of a manned mission to Enceladus by, oh say 2080?

If it has life, then chances are zero -- planetary protection.

 

[RGClark]

Lander missions to Europa possible for costs at the few hundred million dollars range, comparable to the costs for the Mars Pathfinder lander:

Low cost Europa lander missions.
http://exoscientist.blogspot.com/2015/02/low-cost-europa-lander-missions.html

Bob Clark

 

[RGClark]

I want to do a similar calculation for a low cost mission to Enceladus. What's the Hohmann transfer delta-v from LEO to Saturn at closest approach? What's the travel time then?

Bob Clark

 

[dumbo2007]

Apparently the solar system is awash

http://www.nasa.gov/jpl/the-solar-system-and-beyond-is-awash-in-water/index.html

 

[RGClark]

RUSSIAN BILLIONAIRE YURI MILNER PLANNING TO SEARCH SATURN MOON ENCELADUS FOR ALIEN LIFE BEFORE NASA CAN.
BY DAMIEN SHARKOV ON 11/23/17 AT 6:30 AM
http://www.newsweek.com/looking-ali...uld-beat-nasa-saturns-mysterious-water-720675

I proposed such a privately funded mission for Europa:

Sunday, February 15, 2015
Low cost Europa lander missions.
http://exoscientist.blogspot.com/2015/02/low-cost-europa-lander-missions.html

This could also be done for an Enceladus mission, privately funded.

A Falcon 9 launched Europa mission might cost in the range of $80 million for the launch cost only. For the robot rover, we might make a comparison to the Mars Prospector mission, which cost $150 million. However, privately funded, the examples of SpaceX and Orbital Sciences for both their launchers and their space capsules, suggests privately funded such a rover might be developed for a tenth the cost of the government funded amounts, so perhaps only in the range of $15 million.

For a Falcon Heavy mission, carrying a 1 metric ton robot rover, comparable in size to Mars Curiosity, the launch cost would be in the range of $190 million. Again as privately funded, the rover cost might be one-tenth that of the $1 billion Mars Curiosity cost, so only ca. $100 million.


Bob Clark