US Navy and Marine Corps boffins are chuffed with themselves today, after inventing a crafty underwater probe podule which can be dropped into the sea, sink to a pre-programmed depth, remain there for weeks or months and then at some point rise to the surface again - all without using any electrical power. This last is a good …
Wash your mouth out!
"Nuclear power isn't a realistic option for a small instrument package."
Nuclear power is the only option for absolutely everything! At least I thought that was the acepted wisdom around here...
Any gas will do. Methane generating bacteria should be equally as good (and much simpler to obtain).
Lighter than air
Hydrogen is lighter so for a given volume/number of molecules it should give them better lift. True any gas should be lighter than sea water so it depends what bacteria you can easily keep alive/suspended & fed at depth.
Same reason airships used to use Hydrogen not Methane...
Hydrogen has a greater buoyancy than methane so you need less food/fewer bacteria to generate enough hydrogen to lift the vessel than would be the case with Methane - and of course the more food you need the more the vessel weighs and the more food you need.
How do they report back?
"naval antisubmarine operations" ... "frogman attacks"
Those need immediate reporting. If there's wires back to the surface to send data, they can be used for power as well. If there aren't, the data only gets back when it surfaces months later.
And of course it still needs some power to run the instruments, so just what is the advantage of these?
...is that you dont need power to get the thing back on the surface!
That means the batteries you were going to use to do that can be used to power higher precision, and allround better instruments. And as opposed to the throwaway ones you can afford to use better and more expensive instruments because theyre no longer one use throwaway.
I had a digital watch in the 80's
That ran on water, it was on tomorrows world and everything. Perhaps they could've just ganged a few of them together. I can't find a suitable pic, but I did have one of these too: http://www.mobypicture.com/user/postma/view/6018223 albeit in grey rather than purple.
I had a girlfriend in the 80s
...that ran on vodka, but I could understand how that worked. How did your watch work?
*Hydrogen* generating bacteria.
Note this *should* make all those Hydrogen economy eco wet dreams a *lot* further forward.
As long as you keep the Hydrogen away from the Oxygen in the atmosphere.
Ohhh. I see a small problem.....
"As long as you keep the Hydrogen away from the Oxygen in the atmosphere.
Ohhh. I see a small problem..."
If the bubbles surface & if they ignite they will form fresh water over the sea... not such a problem.
We have known about hydrogen making bacteria for ages (I thought) as they have said they could make fuel that way for a long time... problem is that they don't make it very fast so you would need vast seas of it to make large volumes quickly. Perhaps they plan to crack a tank and make the ocean give us fuel :-D
Can't they just use...
... the heat from a decaying isotope, like the Voyager probes do?
I think you will find that is called Nuclear Power; they just wanted to be careful about telling the public that we just fired a warhead into space to great alien visitors...
RTGs - size and buoyancy
RadioThermal Generators are probably too big and expensive for an application like this, where thousands of devices will be deployed.
In fact (having just googled it) RTGs are too big. Terrestrial ones are several hundred kgs; those used in space probes can be brought down to ten or so kgs, but that must be by sacrificing shielding.
A key bonus which RTGs won't offer is of course buoyancy - this generates its own lifting gas, while RTGs would be very heavy.
And the first time...
...One of them washes ashore somewhere?
the episode of space 1999 about the voyager probe?
Not allowed to do it
It would constitute dumping radioactive material into the ocean which is forbidden by international treaty.
forbidden by international treaty.
and that would stop who? and how?
So it does use power
it is just generated by bacteria.
If you fit some control fins, a bacteria-generated-hydrogen burning engine and a prop to the podule then get DARPA to teach the bacteria to drive...
Someone had invented a gliding version a while back
Same variable bouyancy concept, except with guidance and winglets. When sinking it would glide off in the programmed direction, and then when floating upwards again it would also glide off in the programmed direction. Repeat the down and up cycle endlessly and it could cross the ocean using an AA battery [hyperbole warning].
I for one stand ready to welcome...
Our symbiotic bacteriorobotic masters from the deep.
Skynet? Nah...... Seanet.
although "zero-power" isn't really true, it uses whatever food the bacteria are digesting as power
not just a research probe
Sounds like a great way to make a device that could be dropped off for intel work or a self-powered torpedo.
This is clearly all in support of laser-bearing sharks:
The ZPBC could also be used to provide in-water optical data to enhance models for underwater visibilities, [for sharks] laser penetration depths [and distances], diver and target vulnerability assessments [vulnerability too laser-wielding sharks], electro-optical system performance predictions [lasers], and refining numerical models [size/weight/number of sharks with lasers].
The subscript here is clear as can be.
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