What would space crafts designed by aliens living in an aquatic world be like?

[insert_name]

50 minutes ago, monstah said:

On that last paragraph, I think the discussion in this topic is not wether they get to that technological point, but assuming they already did develop some technology, how would they go about its space stage, right? The other two points are valid.

But then, we're talking of "aquatic" worlds, meaning liquid. We're thinking of water because it's common to us, but it could very well be ammonia, or I don't know what. Some other liquid that doesn't interfere much with radio and isolates currents, like our atmosphere instead of our oceans. Dynamos might be difficult without metals/magnets, but chemical batteries are well feasible, provided the environment doesn't conduct the electricity away.

Same with the conductors; I think we're being limited to the metal-and-fire-based tech we're used to. Some alien world could have different available materials, or evolution might just lead them to completely different methods.

for that matter, would the world be entirely water,  or have some land, and would it be salty or relatively fresh

[Rakaydos]

2 minutes ago, insert_name said:

for that matter, would the world be entirely water,  or have some land, and would it be salty or relatively fresh

My suggestion would be shallow seas and/or contenental shelf based. Archipelicos of coral reaching the surface can be "explored" in pre-history, and later can provide the basis of tech that simply cannot be made below water, no matter how advanced your organic chemestry tech.

[Snark]

So, setting aside for the moment the problem of "how would they develop technology in the first place":  Let's assume that they do somehow get past that potential obstacle.  They've got all the technology that we have (let's include near-future, to be generous).  What would their spacecraft look like?

I was thinking about this, and the comment that folks have made about how heavy they'd have to be in order to lug all that water around, and how it's 800 times denser than air, etc.  Lots of comments like that have been made, here's a representative sample:

6 hours ago, kerbiloid said:

As the inner space of a pressurized cabin is ~ 5 m³, this means they would launch, say 8 t of water and additional pumps.

I think RainDreamer had the right idea:

6 hours ago, RainDreamer said:

Given the enormous mass requirement then, can they instead minimize the amount of water they need to carry to space by using spacesuits filled with water (and exchange the water inside periodically) instead of filling their whole hab space with water?

Not only is that a good technical solution... but we need to make sure we're not limiting ourselves to human psychology.

For example, let's ask ourselves:  Why do humans even have habs in our spacecraft?  Why do we have open spaces to move around in, instead of being sealed up in suits or little coffin-like things?  Well, I can think of a few reasons:

• Air doesn't mass much.  Providing hab volume isn't ludicrously expensive in terms of mass.  (More than a suit-based solution would be, but not insanely more.)
• People are very visually-oriented critters.  We like to be able to see each other, and see all the stuff in our ship.  Hard to do that if you're sealed up in a small volume barely larger than your body.
• People are prone to claustrophobia.  Yeah, spacecraft are pretty cramped, but it's not like being sealed in a coffin.  Put most humans in a tiny volume for an extended period of time and they'll go nuts.  Yes, astronauts are tough, but there are limits.
• People need space to exercise in zero gee.

I think it's entirely plausible that none of these would apply to an aquatic species:

• Their habitable volume is much denser than ours.  So that gives them a strong physics-based incentive to keep it as small as possible.
• I think it's highly likely that aquatic critters are less visually-oriented than we are.  That's not to say they don't use vision, but I think it's plausible that they'd attach greater importance to touch, or sound waves, or minute electrical currents, or the like.
• I suspect they'd be considerably less prone to claustrophobia than we are.  Leaving marine mammals out of it, the most intelligent sea critters on Earth are octopi.  They love squeezing into narrow hidey-holes.  I would expect that an octopoid race would do just fine in cramped quarters.
• They normally live in conditions that are effectively close to zero gee anyway-- they may not have the same exercise requirements that we do.  And the less they move around, the lower their metabolic requirements, which makes keeping them supplied with oxygen and food (or their equivalents) that much easier.

So I could see them building ships whose lifesystems aren't the open areas that we use-- it might be that each crewmember has a coffin-like compartment that's barely bigger than their own body.  Or maybe they're all smushed together in one comparment that's barely bigger than the total body volume of the crew.

If you do it that way... I don't see that their mass requirements would necessarily be much more than ours.  They wouldn't have to lug lots of water around (most of the water volume, in fact, might be in the guts of their filters/recyclers rather than their actual "crew space").  And having much smaller living quarters than ours would save mass on structural requirements.

Finally, one last side benefit-- floating in zero-buoyancy conditions is a great way to withstand acceleration.  I expect they could tolerate gee forces much higher than we can, which would potentially open up some engineering possibilities.  Slam into atmosphere at thirty gees?  No problem. 

Also:  for extended space voyages, humans run into physiological problems in zero gee, and engineering solutions for this tend to be bulky and awkward.  I bet an aquatic species would have much better long-term zero gee tolerance.

[insert_name]

I do think it would be really cramped in most areas, but they will need some room to eat, do experiments etc. Also how would Eva work?

[Snark]

17 minutes ago, insert_name said:

I do think it would be really cramped in most areas, but they will need some room to eat, do experiments etc. Also how would Eva work?

Depends.  Why wouldn't they just eat out of a tube that goes right into their appropriate orifice?

As far as doing experiments, EVA, etc. is concerned:  that's totally dependent on what level of technology you're assuming.  Are you assuming that they are at or below our current tech level?  or are you willing to grant them a technology that may be 50-100 years ahead of where we are now?

The fact is, there's no reason the ship couldn't have robotic manipulators for taking care of things you'd normally do with EVA, or manual execution of experiments.  I would be surprised if human spacecraft need that a hundred years from now.  People go EVA now because our telepresence technology isn't good enough yet to handle all the things that an EVA human can do... but the operative word there is yet.  Give us another few decades and I seriously doubt there will be any practical reason for a human to go EVA.

And if you did need EVA-type abilities:  well, maybe they just live in their suits, as RainDreamer suggested.

[RainDreamer]

So since we are now back to the topic of aquatic alien spacecraft design, let's think about how they launch them. Would they design rockets like Sea Dragon, launching from water surface? Would they use balloon-assisted launches? Maybe artificial island/floating base? Or would they launch directly from ocean floor?

 

How would they communicate with the spacecraft? Antenna poking from underwater? Or maybe laser instead?

[insert_name]

1 hour ago, Snark said:

Depends.  Why wouldn't they just eat out of a tube that goes right into their appropriate orifice?

As far as doing experiments, EVA, etc. is concerned:  that's totally dependent on what level of technology you're assuming.  Are you assuming that they are at or below our current tech level?  or are you willing to grant them a technology that may be 50-100 years ahead of where we are now?

The fact is, there's no reason the ship couldn't have robotic manipulators for taking care of things you'd normally do with EVA, or manual execution of experiments.  I would be surprised if human spacecraft need that a hundred years from now.  People go EVA now because our telepresence technology isn't good enough yet to handle all the things that an EVA human can do... but the operative word there is yet.  Give us another few decades and I seriously doubt there will be any practical reason for a human to go EVA.

And if you did need EVA-type abilities:  well, maybe they just live in their suits, as RainDreamer suggested.

I was thinking they would have a similar level of tech to us, I also wonder if they would come up with segmented arms used in robotics, seeing as they have tentacles.

considering these are small octopi, we could afford a small tank like a couple liters, I was thinking they would be roughly a sentient version of a veined octopus, except more social, so a couple of liters of water would be doable, as for the eva suits, maybe they could swim through a tube into a suit on the outside of the ship, said tube would also function as an eva tether

[kerbiloid]

Not exactly about water species, but on a similar theme: Robert Sheckley, "Hands Off"

[YNM]

Guess the answer heavily depends on their anatomy. A bony creature (be it exo- like lobster or endo- like fish and us) probably can handle more physical stress than non-bony creature. Going to space almost always means high-G, so if you were to design a suit for octopus and for lobster it'll be different.

[Snark]

10 hours ago, YNM said:

Guess the answer heavily depends on their anatomy. A bony creature (be it exo- like lobster or endo- like fish and us) probably can handle more physical stress than non-bony creature. Going to space almost always means high-G, so if you were to design a suit for octopus and for lobster it'll be different.

Actually, non-bony creatures should handle high gees just great.  They're floating with pretty close to neutral buoyancy in their surrounding liquid, which is about the best protection against acceleration that it's possible to have.  Bony creatures would have less tolerance for acceleration, because their different body components have significantly different densities, resulting in mechanical stress during acceleration.

I bet a boneless critter that's of near-uniform density (like an octopus) could handle dozens of gees of acceleration with no trouble at all, as long as it was floating in its liquid.  (There'd be a lot of mechanical stress on its container to hold the liquid in, but you make that out of sturdy stuff.)

Another side benefit of boneless critters:  engineering things like docking ports, EVA suits, etc. becomes much easier, because they can squeeze through tiny holes.  An octopus the size and mass of an adult human can squeeze through a hole a couple of inches in diameter.  So an EVA suit just needs a small hole on the back for ingress/egress, and docking ports can be tiny.

[RainDreamer]

What are some possible high G launch vehicles that they may use in their aquatic world then?

 

Also, considering all of their landing would be splashdown, while they can survive in higher g, and they would have no need for the landing craft on their planet to remains in surface water, maybe they would attempt some form of aquabrake (is that even the proper word) to slow their craft down without parachutes? Probably just lifting body design alone, since that works in liquid too.

Edited April 13, 2016 by RainDreamer

[sevenperforce]

Yeah, a boneless creature has some serious advantages. Especially if they can survive in open air by respirating through their skin. 

It's even theoretically possible that a boneless creature could survive unprotected EVAs without difficulty. If they can handle the transition from high pressure to atmospheric pressure then that last atmosphere shouldn't be much of a problem if they can mitigate moisture loss. 

Ability to handle very high gees could lead to ground-based launches like launch cannons, especially because it is far easier to build a large underwater structure. 

[insert_name]

37 minutes ago, RainDreamer said:

What are some possible high G launch vehicles that they may use in their aquatic world then?

 

Also, considering all of their landing would be splashdown, while they can survive in higher g, and they would have no need for the landing craft on their planet to remains in surface water, maybe they would attempt some form of aquabrake (is that even the proper word) to slow their craft down without parachutes? Probably just lifting body design alone, since that works in liquid too.

I doubt it, impacting water at high speeds tends to destroy things

[Snark]

38 minutes ago, sevenperforce said:

Yeah, a boneless creature has some serious advantages. Especially if they can survive in open air by respirating through their skin.

Except that being in open air would remove all of their acceleration resistance, and make them highly vulnerable to getting squashed.  They're protected from G-force only while floating in liquid.

39 minutes ago, sevenperforce said:

It's even theoretically possible that a boneless creature could survive unprotected EVAs without difficulty. If they can handle the transition from high pressure to atmospheric pressure then that last atmosphere shouldn't be much of a problem if they can mitigate moisture loss.

I don't see why they'd be any more resistant to low pressure than humans would.  That "last atmosphere" is a pretty important one.  It's what stops the water content of their bodies from boiling at room temperature.  Explosive decompression is no fun.

17 minutes ago, insert_name said:

I doubt it, impacting water at high speeds tends to destroy things

True... but it depends what you're trying to save.  If all you're trying to do is recover the crew, they could be squeezed into something pretty much like a cannonball that could be made tough enough to handle a water impact at terminal atmospheric velocity.

That said, though, I would imagine that the most useful place to be able to tolerate high gees would be aggressive aerobraking.  It opens up options when you don't have to worry about turning the crew to jelly.

Also, perhaps,

42 minutes ago, sevenperforce said:

Ability to handle very high gees could lead to ground-based launches like launch cannons

...maybe not actual cannons (we're talking thousands of gees there), but certainly some sort of rail-based launch system would become a lot more practical if you can go to a few dozen gees instead of being limited to the paltry few that a human can tolerate.

[Wjolcz]

You guys do realise there's that one snail that actually somehow consumes some sort of metal and then uses it to form it's shell/spikes/whatever it has on it's back. Don't know it's name though.

Now let's assume there's a species that also does that. The sqiod people use the rocks, migrate somewhere else where such snals live, stone one of them to death and see those metal thingies can be bent and sorta joined together when put in the heat stream of one of the geothermal volcano-thingies on the bottom of the sea.

Early metallurgy! Bam!

Found it: https://en.m.wikipedia.org/wiki/Scaly-foot_gastropod

[RainDreamer]

I wonder how their space station are designed. If they live in liquid, that would give them natural radiation shield and they would only need to worry about puncture from micro meteorites. But then liquid is heavy to launch around. What would they leave inside the space not filled with liquid then? Vaccum? Air from their world's atmosphere?

If they only live in spacesuits filled with water, that might limit their mobility the same way it limits our astronauts, and maybe lower the effectiveness of radiation shielding? What happen if there is a leak?

[lude]

Wouldn't an aquatic society, unable to use oxygen to make fire, be left in a pretty primitive state since oxidation by oxygene is necessary to provide us with most of the tools to build an advanced society with technology and all that stuff?

 

We're only such masters of fires because cooking became a kind of prestomach for us (and all the other nice things we could use it for, this is also the reason why civilizations that endure a winter have put even more energy in winter into finding new appliances for the fire meme)

 

-- edit --

 

also those are some badass snails and not even the only marine life that can create metally stuff, I dunno what it was I'm thinking off but it made tiny metal spikes, sadly I don't find interesting stuff about it, but there's still more animals doing stuff like that.

Edited April 16, 2016 by lude

[Spaceception]

Idea: Since humans can Breathe liquid under certain conditions, would it be possible for aquatic aliens to adapt to breathe air? Maybe through lung adapters that could allow them to do that, maybe then they could send their people into space, otherwise, I only see them sending uncrewed vehicles into space at the most.

What do you think?

[PB666]

44 minutes ago, Spaceception said:

Idea: Since humans can Breathe liquid under certain conditions, would it be possible for aquatic aliens to adapt to breathe air? Maybe through lung adapters that could allow them to do that, maybe then they could send their people into space, otherwise, I only see them sending uncrewed vehicles into space at the most.

What do you think?

You mean like many littoral molluscs, many crustacean species, amphipods, amphibians, lungfish and amphioxus, absolutely positively it would not be possible, except on the 10000s of occasions where it is possible. 

 

[Spaceception]

Oh, right, I didn't think.

 

Unless, they weren't amphibious, and needed help. I dunno.

[PB666]

25 minutes ago, Spaceception said:

Oh, right, I didn't think.

 

Unless, they weren't amphibious, and needed help. I dunno.

Theres a size limit on crustaceans and on fish out of water there is a limit to how much weight out of water the peritoneal cavity can support for prolonged periods before rupturing. However if they were exposed starting from young age the connective tissue might build in response. As long as you kept the visceral weight below say 5 kg.

Kept the gills moist. Saltwater fish and electronics, this would never work.

Do I need electronics to be a sentient alien, if the answer is yes then most aquatic will never directly be aliens.

Remember E = hv, remember that we use this for GPS, telecommunications, ground tracking etc. You have to keep that in mind. Hydrophobic species also have a problem, excessively dry environment results in static discharge build up, and less gaseous atmospheres allow for more easier transfer. Thus you could be blowing circuits right and left if you combine both.

[magnemoe]

1 hour ago, Spaceception said:

Idea: Since humans can Breathe liquid under certain conditions, would it be possible for aquatic aliens to adapt to breathe air? Maybe through lung adapters that could allow them to do that, maybe then they could send their people into space, otherwise, I only see them sending uncrewed vehicles into space at the most.

What do you think?

Lung fish and many amphibians can breath both, air breathing gives more oxygen so it might be an good solution for an big brained species living in shallow water like corral reefs. Bonus is that you can go on land if predators is after you. Now have them raise babies on land like seals for more evolution pressure.
Too lite land for much land animals, however an plant like bamboo would be priceless 
 

[Exploro]

On 4/12/2016 at 1:30 PM, Snark said:

Here's another thing to consider, which I haven't seen anybody mention yet:  Aside from the technical difficulties of developing technology underwater (no fire; chemistry really hard to do)... how would sea life even know that space exists in the first place?

Assuming a hypothetical sentient aquatic creature lives at depth shallow enough to see the light from the local star they'd have to have recognized that the source of that light is above the fluids surface. They may not initially recognize the existence of outer space in the same sense as we do; but at least it be the idea that sets in motion the pondering of exploration as the stars and wanderings of the planets did for our species thousands of years ago.

Edited June 1, 2016 by Exploro

[kerbiloid]

A nightmare dream of underwater creatures:
They are swimming inside a giant water ball trembling inside an endless empty space, and pouring out into the abyss...

[DChurchill]

On 4/12/2016 at 10:01 AM, Rakaydos said:

Keep in mind, water is heavy. Theit life support requirements wll be much harsher than our own.

Yep. A cockpit full of water, the pressure being irrelevant since it's incompressible anyway, has a lot more issues than O₂ at 5 psi. The inertia on that would be a pain to deal with.