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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.
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.
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!"
Way ahead of you.
http://planetaryprotection.nas...
I love Jesus, except for his foreign policy.
The time is largely spent in political wrangling and procurement. Once people figure out how to make money with space flight (and that will happen), things will go much more quickly.
Private companies are probably going to be reluctant to invest significantly in space flight until property rights have been worked out. No point in spending billions on mining an asteroid only to have people tell you that you don't own it, on top of an already very risky operation.
The Asteroid Redirect Mission might be the most important upcoming mission. It will demonstrate that this sort of thing is feasible, which will lead companies to lobby and pressure politicians to create more of a legal framework for private space industry and mining.
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.
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!"
For the love of $DEITY how about doing a cursory search before ranting?
http://en.wikipedia.org/wiki/A...
Yes it's used. Yes even for space applications. No it have nothing to do with perpetual motion machines...
They're talking about the exposed hydrocarbon seas. They're mainly confined to the poles. The largest, Kraken Mare, is larger than the Caspian Sea, though is only believed to be about a tenth as deep. There's still some question as to whether the surfaces freezes, and if so, whether it's for how long. For any frost to float it would have to contain nitrogen bubbles. Some very small waves are believed to have been observed.
Exactly what makes them up, their source, how they behave, etc is all quite speculative right now. Wikipedia describes them thusly:
"That girl is a witch!" "Yeah, but she's our witch. So cut her the hell down!"
I don't know but I like to imagine it. Cynthia Phillips of SETI says when looking for life, go where the water is and there's a lot of water on Europa. When I first heard her say that, I always imagine a submarine that bores down into the ice and then goes cruising around taking pics and vids of aquatic life. Of course in real world it will take considerable effort to first land, then go through the ice, then submarine around [and a zillion other things that must be done to make it all work]. (etc. etc. etc). And there may not be any life at all.
mfwright@batnet.com
"Sky Of Orange".
And sea of polyethyline.
"Sea of polyethyline".
In our Titan
"In our Titan".
Submarine
"Submarine"
There's also a lot of water on Titan, so again, your point? Titan is one of two bodies in the solar system (the other being Europa) where there's a high degree of confidence that there's a global subsurface ocean deep enough to fully decouple the crust from the mantle / core. The subsurface tides on Titan are so strong that the whole mercury-sized moon buckles 10 meters depending on where it is in its orbit.
So again, why the obsession with Europa and not Titan? Europa = subsurface ocean, fine. Titan = subsurface ocean, extensive organic chemistry, weather, an atmosphere that facilitates exploration, surface hydrocarbon seas, and tons more. Not to mention that its five times bigger.
"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!"
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!"