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

[PB666]

33 minutes ago, DChurchill said:

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.

If you don't think the pressure of water is an issue, watch what happens to it when you remove all pressure.

1. Boils instantly

2. Freezes rock solid in seconds.

3. Lyophilizes over a longer period of time.

 

[DChurchill]

57 minutes ago, PB666 said:

If you don't think the pressure of water is an issue, watch what happens to it when you remove all pressure.

1. Boils instantly

2. Freezes rock solid in seconds.

3. Lyophilizes over a longer period of time.

 

Right. But in the case of how much mass it has for a given volume, pressure is irrelevant.

Edited June 3, 2016 by DChurchill

[Elrond Cupboard]

The thread title reminded me of https://en.wikipedia.org/wiki/Surface_Tension_(short_story). A great yarn, easy enough to find as a PDF on the net. 

[TrooperCooper]

They would not have developed. In order to get a spaceprogram going, you need high energy tech. How often is a submerged alien-scientist able to repeat a high voltage experiment? Did you ever fiddle with your plugged in toaster while laying in your bath tub?

[Exploro]

1.) Just because we require sensitive electrical systems to make space travel possible does not necessarily mean another sufficiently intelligent race would too.

2.) Consider the electric eel of Earth can generate bio-electricity. It obviously does not short itself out nor harm it's neighbors; unless it chooses to do so in pursuit of prey or in self-defense. Therefore it is possible to generate and conduct electricity via non-mechanical means within an aquatic environment.

Edited June 4, 2016 by Exploro

[Spaceception]

33 minutes ago, Exploro said:

1.) Just because we require sensitive electrical systems to make space travel possible does not necessarily mean another sufficiently intelligent race would too.

2.) Consider the electric eel of Earth can generate bio-electricity. It obviously does not short itself out nor harm it's neighbors; unless it chooses to do so in pursuit of prey or in self-defense. Therefore it is possible to generate and conduct electricity via non-mechanical means within an aquatic environment.

Fire's still a problem though.

[Exploro]

Spacecraft structures need not be limited to metal alloys. I recall that in one case; the X-33, a traditional metal fuel tank was to be replaced with one made of composite material. While unsuccessful in that project; Northrop Grumman succeeded in perfecting the technique to manufacture such a tank in the early 2000's. What is more is that composite materials can be naturally manufactured. Consider that spiders produce a silks that; pound for pound, are stronger than steel. It is also superior in performance compared to the next best man-made material; Kevlar. This material is produced at benign temperatures and without the use of toxic chemicals. It's conceivable that if we can replicate the manufacture of spider silk that it could be used in the production of composite structures.

[Hannu2]

If we assume that aquatic aliens (for example species with squid like tentacles which are able to manipulate their environment with precision compared to fingers) would have succeeded to develop technology needed to space operations, they would surely have metals, composite materials etc. Rockets would be very similar than ours and they would operate from some kind of floating ships. Aerodynamics would restrict that. I think that they would need some kind of thin water filled space suit in manned operations like humans need an air filled suit in EVAs. Water filled cabins would be too heavy and probably such a species could not achieve manned flights without inventing a suit compatible with their anatomy and respiration functions and possible to use during whole missions. Probably they would need such a suit for aviation before spaceflight era.