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NASA Releases Details of Titan Submarine Concept
Zothecula writes: Now that NASA has got the hang of planetary rovers, the space agency is looking at sending submarines into space around the year 2040. At the recent 2015 NASA Institute for Advanced Concepts Symposium, NASA scientists and engineers presented a study of the Titan Submarine Phase I Conceptual Design (PDF), which outlines a possible mission to Saturn's largest moon, Titan, where the unmanned submersible would explore the seas of liquid hydrocarbons at the Titanian poles.
"At its heart, the submarine would use a 1 kW radiothermal Stirling generator. This would not only provide power to propel the craft, but it would also keep the electronics from freezing. Unfortunately, Titan is so cold that it's almost a cryogenic environment, so the waste heat from the generator would cause the liquids around it to boil and this would need be taken into account when designing the sub to minimize interference. However, NASA estimates that the boat could do about one meter per second (3.6 km/h, 2.2 mph)."
"At its heart, the submarine would use a 1 kW radiothermal Stirling generator. This would not only provide power to propel the craft, but it would also keep the electronics from freezing. Unfortunately, Titan is so cold that it's almost a cryogenic environment, so the waste heat from the generator would cause the liquids around it to boil and this would need be taken into account when designing the sub to minimize interference. However, NASA estimates that the boat could do about one meter per second (3.6 km/h, 2.2 mph)."
At least they will all be fusion powered by then.
If we are designing a submarine for use somewhere exotic and oil-rich wouldn't it make sense to save time by adding the weapons systems now? You know we'll end up needing them, and designing them in after the fact will be much more annoying and probably take longer.
TIL: I will likely be dead before the planets of our solar system are widely investigated. The time necessary to plan and execute an interplanetary mission is daunting.
Just light some signal fires
The only thing necessary for evil to triumph is for it to be pitted against a slightly greater evil
NASA Institute for Advanced Concepts is a way of giving relatively small amounts of money ($100,000) to outside researchers to begin to flesh out advanced ideas. One hundred K is not going to buy you a fully designed Titan submarine. So, this is a idea, but not much more, and may have little or even no resemblance to NASA thinking, NASA plans or anything that is actually done later.
We'll need an environmental impact study to analyze the potential negatives effect of this man-made exploration device on native species.
Wrong FLA surely, sounds more like a job for the NUMA
At its heart, the submarine would use a 1 kW radiothermal Stirling generator.
In other words, an impobability drive. Beware of the whales.
Nae king! Nae laird! Nae yurrupiean pressedent! We willna be fooled again!
Seems like you ought to be able to do better in terms of propulsion when you can easily vaporize the liquid you're immersed in.
The freezing point of methane is -182C so there's not a big spread between freezing and melting.
Apparently, methane with dissolved nitrogen has a wider spread between freezing and boiling, but I don't know how much it helps.
Simple. Declare war on Titan and justify it that Titan's hydrocarbon revenue will cover the cost of it!
Plus it finally gets us away from falling victim to one of the classic blunders, "Never get involved in a land war in Asia."
Do not look into laser with remaining eye.
Just a guess, but if you want one-way communication you jettison a few uplink modules throughout the mission and they relay data to the orbiting probe that delivered the sub. If you want bidirectional communication you either tow an antenna cable strung out behind, or you run a buoy line up to the surface.
Do not look into laser with remaining eye.
What you're describing is an incredibly challenging tasks. One needs several missions to get to better know Europa in general, and specific potential entry areas in particular, first. These missions are going to be expensive and have long lead times. And an actual boring / submersible mission is going to be extremely expensive.
Titan has one main strike against its exploration, that it's so dang far away. But almost everything else about it is tailor-made for exploration. It's ideal for aerocapture. It's trivial to stay aloft, at an altitude of your choice, be it by hot air or lifting gas balloon, blimp (likewise), helicopter, fixed-wing aircraft, tilt-wing aircraft, etc. Low temperatures pose some difficulties but can be nice for electronics, and the rate of heat loss (even in a hot air balloon concept) is so low at such low temperatures that you don't need very big heat sources. The hydrocarbon seas are permanently exposed for whatever means of exploration (aerial, boat, submarine) you choose. Ascent requirements (sample return, for example) are surprisingly low versus a body of that size due to the ability to fly so high in the significant pressure / low gravity environment before needing to fire rockets. And so forth. And there's so darn much we don't know about Titan, perhaps even more than Europa. There's constant complex organic chemistry going on in the upper atmosphere of which we know almost nothing, and probably even some on the surface. There's probable liquid water under the surface and cryovolcanoes that erupt it to the surface. There's earthlike weathering processes done with/to completely different materials, and the entire gas cycle is a giant mystery right now. So yes, I'm pretty excited about whatever mission goes to Titan next.
Too bad the next launch window to Saturn (2018, 4,13km/s delta-V, 8,2 years) is simply not going to happen. : There's not going to be such a low delta-V/time window for a long time - 2020 is 5,18 km/s / 11,0y; 2021 is 4,80km/s / 8,8y; 2024 is 4,81km/s / 10,4y; etc. So if we're lucky maybe we could get the 2021 window (though the increased delta-V reqs would significantly hurt the payload)... otherwise, there won't be a spacecraft getting to Saturn before the mid 2030s. :
"That girl is a witch!" "Yeah, but she's our witch. So cut her the hell down!"
All these worlds
are yours except
Europa
attempt no
landing there
Truly, you're a fucking moron.
Damn, I just knew those NASA engineers were forgetting something!
Probably they would do it in a manner similar to how they do it with conventional submarines: occasionally surfacing and transmitting normally, or else releasing a buoy with communications capabilities.
And speaking of liquid water under the surface, has anyone else noticed how almost every body in space that people point a camera at long enough seems to have evidence of "unexpectedly large" amounts of heat under its surface, esp. at surprisingly shallow depths? I really want to know what it is that people are overlooking because it keeps happening again and again, people expect to see dead rocks drifting through space and find out that they're still surprisingly alive with some process or another that means internal heat.
"That girl is a witch!" "Yeah, but she's our witch. So cut her the hell down!"
Due to the large amount of data that needs to sent to Earth, the submarine needs a large dorsal fin that includes a planar phased-array antenna. While operating, the submarine would surface for 16 hours per day for Earth communications during which it would study its surroundings using a mast camera.
If the properties of longer-chain hydrocarbons apply to that of supercooled liquid short-chain hydrocarbons, then it should be pretty transparent to RF. That said, if it was a problem, the solution is as simple as "surface".
"That girl is a witch!" "Yeah, but she's our witch. So cut her the hell down!"
There are still arguments over how thick the ice on Europa actually is, varying from estimates that it could be as thin as a couple hundred meters, to alternative models using ice that behaves ductile over long time periods that allow for the ice to be 100+ km thick.
Note : A Titan day is 15.94 Earth days
Doesn't Titan have a solid crust of ice like 1 or a few kilometers thick? A submersible rover is a super cool idea, but first you have to get it to the ocean. I'm confident they can figure out how to get something to Titan, but getting it through the ice to the ocean is something else entirely. A drill seems expensive from a weight and fuel standpoint, and an explosive would have to be nuclear in size to crack it and cause all sorts of problems.
Or am I confused; are the oceans exposed?
Ah yes, mercury as a structural material...
https://en.wikipedia.org/wiki/...
One of my favorite hard sci-fi novels. Cheesy as all hell, and just a platform for Hogan to tilt at this favorite strawmen, but fun.
Mostly random stuff.
On Titan the view of Saturn is edge-on to the rings as Titan is in the ring plane. So the rings of Saturn would not be visible in the sky.
Seeing the artists get this wrong in the 2009 Star Trek movie is a bit forgiving, as they need to impress their audience. But on Gizmag?!? I would have expected better.
It is dangerous to be right when the government is wrong.
because I want to see the little fishies.
mfwright@batnet.com
I'm sure the name tickles those who obsessively play Kerbal Space Program... not that I do... or know people who do... (hides his drawings of SSTO designs).
Cool concept. Let's hope it comes to fruition.
Give me a ping, Vasili...
Hmm, just another thought which I haven't seen anywhere else. Orbital velocity through Titan's ionosphere would be about 1500 m/s, if my calculations are right. Exhaust velocity on ion engines ranges from tens of thousands to millions of meters per second. So a ram scoop to refill propellant is plausible, your drag should be well less than your ability to reboost with the propellant you acquire, even if efficiency is low; in practice you should be able to capture much faster than your burn rate. While all ion engines have certain elements which are "optimal" in terms of performance, you can generally use whatever ions you want without too dramatic of a sacrifice in terms of isp and thrust (so long as there's no corrosion problems or the like).
So, for a sample return mission:
1) A probe with detachable, flying lander (each RTG-powered) is boosted to LEO. As for the lander, I personally like the tilt-wing design, as it allows easy of landing and requires only a small RTG (it can fly in short hops, replenishing batteries on the ground while during surface science), but allows the high speed and range of travel of a fixed-wing plane.
2) The probe begins a decade or more ion-propelled journey to Saturn, with only enough propellant to reach a stable orbit in Titan's upper atmosphere (and possibly some minor exploration of the Saturnian system en-route).
3) The lander drops off, aerobrakes over the course of a few weeks, and then explores the planet for a year or so while the orbiter replenishes itself. A tilt-wing aircraft could probably explore all of the most interesting places on the planet in that timeframe and take numerous small samples). The lander only needs a small antenna, as the orbiter can act as a repeater to Earth.
4) When exploration and propellant refill are done, the lander then flies back up through the atmosphere to as high and fast as it can, then activates a rocket stage (1500-2000 m/s delta-V) to re-rendezvous with the probe. The spent stage is ejected.
5) The probe returns to Earth on ion power using its propellant from Titan (possibly with some minor exploration of the Saturnian system en-route). Upon return to Earth, the leftover propellant could itself be studied as a sample return in its own right (it could even be gathered into different tanks from different altitudes via an elliptical orbit if so desired).
"That girl is a witch!" "Yeah, but she's our witch. So cut her the hell down!"
"The exact blend of hydrocarbons in the lakes is unknown. " - Real question is can you set it on fire?
I only look human.
My mother is a halfling and my dad is an ogre, so that makes me an Ogreling
But there wouldn't be anyone to waterboard.
putting the 'B' in LGBTQ+
We could use that technology to explore the Earth's oceans and exploit, if needed, methane hydrates.
putting the 'B' in LGBTQ+
Liberal Senator: If this is a space mission, wouldn't this involve rockets? According to my latest Quinnipiac, 43% of my constituency now supports that trendy new anti-fire movement, and I'm up for reeleection next year. No thanks.
I always thought that with cryogenic temperatures we could use superconductors and something along the lines of the Meisner effect (as long as a source of magnetic field lines exists) for propulsion.
"Sky Of Orange".
And sea of polyethyline.
"Sea of polyethyline".
In our Titan
"In our Titan".
Submarine
"Submarine"
How should a 1kW thermal exhaust get the water boiling around a submarine in an 'infinite' big water reservoir is beyond me.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Of course not! On Titan you would liquid-methane-board the native terrorists!
Is that on the list somewhere? Because I think dealing with people and the base hostile environment of space needs to be solved before we think about putting people in a sub pointed at another ocean.
Suborbital [spaceflight] is the special olympics of spaceflight. - Rei
If by any chance there are 'living creatures' of some type,
they will be remembering this as the "Great Death" (or something equivalent.)
A 1000w heater (the sub) in a big ocean of methane better have a Lot of surface area, if they want to avoid boiling it. :)
Truth isn't Truth - Guliani
What you're describing is an incredibly challenging tasks. One needs several missions to get to better know Europa in general, and specific potential entry areas in particular, first. These missions are going to be expensive and have long lead times. And an actual boring / submersible mission is going to be extremely expensive.
What!?! Next you'll be talking us that even with Apollo levels of funding and political commitment, it'll take us at least 30 years to put a person on Mars.
The pdf says: "Measurement of the trace organic components of the sea, which perhaps may exhibit prebiotic chemical evolution, will be an important objective, and a benthic sampler would acquire and analyze sediment from the seabed." Why would the seas on Titan only exhibit prebiotic chemical evolution? Titan is about the same age as Earth, surely? Would love to know more about the possibilities of evolution of life in such an alien environment.
I'm confused, and you seem to know something or another. why would the rate of heat loss be low? titan is extremely cold, and heat loss goes as the gradient of the temperature correct? Or are you saying there are obvious choices of gas which have very high levels of thermal expansion at those temperatures to make it that the temperature gradient isn't very large?
Except that it always seems to be in excess of what they calculate. It's just one "there's more heat than we expected' after the next... one kind of begins to wonder if they need to figure out why their expectations always seem to be wrong.
"That girl is a witch!" "Yeah, but she's our witch. So cut her the hell down!"
Too bad the next launch window to Saturn (2018, 4,13km/s delta-V, 8,2 years) is simply not going to happen. : There's not going to be such a low delta-V/time window for a long time - 2020 is 5,18 km/s / 11,0y; 2021 is 4,80km/s / 8,8y; 2024 is 4,81km/s / 10,4y; etc. So if we're lucky maybe we could get the 2021 window (though the increased delta-V reqs would significantly hurt the payload)... otherwise, there won't be a spacecraft getting to Saturn before the mid 2030s. :
I think you're looking at launch windows waaaaaay to close to present.
There is no way that NASA, at its current funding level, is going to design, build, and test a nuclear-powered submarine for an interplanetary mission in 3-5 years.
I'm not just talking about Europa. I'm talking Enceladus and half a dozen other moons that were thought to be most assuredly dead but turned out to have liquid water geysers, for example. I'm talking about the unexpected internal heat in our moon. I'm talking about Titan's apparent level of internal activity in excess of predictions. I'm talking about how Io's volcanoes are in the wrong spot based on what we know about how it should be heating. I'm talking about how there's even considered 50-50 odds right now that Ceres has geysers (guess we'll find out the answer to that later this year ;) ), and there's essentially zero tidal heating there. I'm talking the discovery of mega-storms on Uranus, whose fueling heat is still a mystery. I'm talking about not simply the fact that Jupiter and Saturn release more heat than they receive from the sun, but that counterintuitively Saturn's ratio of heat received to heat emitted is more extreme than that of much larger Jupiter. And on and on.
About 3-4 times a year I hear some planetary scientist or another baffled about where the heat is coming from to explain something they're observing in some body or another. I never hear the opposite, never "why is this colder / less energetic than expected". Perhaps there's not one cause, there could be many. But clearly we're not very good at our expectations of how hot celestial bodies should be internally, for whatever reasons.
Who wants to bet that this summer we're going to be hearing, for some reason or another, planetary scientists boggling over New Horizons data, asking "where is the heat coming from to explain X that we're seeing on Pluto? That shouldn't be there."
"That girl is a witch!" "Yeah, but she's our witch. So cut her the hell down!"
Most of what I've read about heat loss on Titan pertains to hot air balloons, so I'll cover that first.
Thermal radiation is proportional to the temperature to the fourth power. So essentially zero. Convective / conductive losses are proportional to the gas density, surface area, and to the absolute difference in temperature. Buoyancy is relative to the relative gas densities, meaning for a given amount of buoyancy in Titan, you're dealing with only a small absolute temperature difference compared to what's needed on Earth for the same amount of buoyancy. The low gravity means you can float higher (in thinner gas) as well, and means that you can use a much smaller envelope at any given height. So convective and conductive losses are dramatically reduced.
All in all, heat loss for a balloon in Titan's atmosphere is extremely low.
Now, a submersible is more challenging, of course, as you're surrounded by a much denser fluid capable of drawing away heat much faster (aka, like the difference on Earth between standing in freezing air vs. swimming in freezing water). But thermal radiation is still essentially irrelevant. The question for conduction / convection becomes what sort of heat profile one plans to design their craft to have. It should be noted that most hydrocarbons have significantly lower specific heats than water, and thus would not be expected to draw heat away as quickly in an equivalent scenario. Also, there's a fairly good chance that these liquids may be rather viscous, so convection will probably be greatly reduced (it all depends on the exact mixtures and temperatures).
"That girl is a witch!" "Yeah, but she's our witch. So cut her the hell down!"
Honestly, I can't think of a more compelling place outside of Earth that we have current, compelling evidence that there is life or lifelike processes ongoing than Titan.
A long mystery on Titan has been, where is the methane coming from? We can see it being converted into the atmosphere into a wide range of organic compounds, various compounds of CHON (the building blocks of life, one might add), and the whole atmosphere should be converted in about 50 million years - yet here's this multi-billion-year-old Mercury-radius moon that still has an atmosphere thicker than Earth's. Some have been detected at over 10000 daltons, so we're talking about big, complex molecules - as well as a lot of bulk simpler organics like ethane and acetylene. A common theory before Cassini-Huygens was that there would be a deep, global ethane / acetylene ocean, with all of Titan's current methane constantly bubbling up from deep within the planet. But this turned out not to be true. So what the heck is happening to all of it?
One theory that had been postulated was that life or lifelike processes on the surface in the hydrocarbon-"wet" sands and the seas are conducting their own cryogenic version of our gas cycle - that is, hydrogen plays the role of oxygen and methane the role of CO2, with various longer chain hydrocarbons, but especially ethylene and in particular acetylene, as the fuels. These are metastable on the surface of Titan. It's like if you set a bowl of sugar out, it's not just going to react with the oxygen in the air, even though that would put it into a lower energy state; you either have to heat it up significantly, expose it to an organic catalyst, or expose it to biological metabolic (catalytic) processes to react it with oxygen and extract the energy. Obviously, there are no widespread significant sources of great heat on Titan's surface. A cryogenic natural widespread acetylene catalyst would be very weird and a remarkable discovery in its own right. So if its breaking down, one would have to seriously consider biological processes as a possibility.
After the theory was proposed, the Cassini-Huygens mission confirmed the paucity of acetylene in the lower atmosphere compared to the upper atmosphere. And then a computer model of the data suggested that 1/3 tonne per second of hydrogen is diffusing from the upper atmosphere to the lower atmosphere, aka - it's being consumed at the surface and regenerated photolytically in the upper atmosphere. Now, this latter research is just a model - we don't know yet if it's accurate. But it's yet more evidence that there might be something unusual on the surface catalytically breaking down organic compounds with hydrogen.
We can also look at what we know about the chemistry that's going on. The longest chain compounds identified thusfar are PAHs - polycyclic aromatic hydrocarbons. Well, one of the major pre-"RNA World" hypotheses (that is, to say, how a RNA World abiogenesis scenario could come into being) is called PAH World. PAHs act as natural scaffoldings for RNA synthesis. Furthermore, laboratory recreations of Titan's atmosphere and the organic chemistry going on therein resulted in the synthesis of all five nucleotide bases as well as amino acids.
Would I bet my car on there being life currently on the surface of Titan? No. But there's some very interesting activity that warrants explanation, and it'd be pretty hard to rule out life or lifelike processes. Certainly more evidence than we're seeing anywhere else. It would have to be very different than life as we know it, no question, and we may be talking about something more like a "hypercycle". But if it's true that there's some sort of catalytic cycle going on on the surface, what could one point to as a more likely cause on a world awash in complex organic molecules than a process based on complex organic molecules? And if you have an environment were you're constantly producing a wide range of organic molecules and these molecules are performing an energy-extractive activity, well, that sure sounds like a perfect setup for abiogenesis.
But... there's a lot of big IFs, so time will tell.
"That girl is a witch!" "Yeah, but she's our witch. So cut her the hell down!"
"...the waste heat from the generator would cause the liquids around it to boil..."
Because there is nothing like studying marine life by boiling it... My only question is will they equip the submersible with a garlic butter sauce or not, because without it, I don't see it being a worthwhile endeavor.