Are there types of animals that can't make the trip to space? (physiologically)

Question

I thought about what kind of animals could make it to space, and I thought about how vertebrates can apparently withstand the G forces need to travel to the ISS, but I hadn't really thought about invertebrates, which I thought may not make it due to the G forces involved, depending on how fragile the organism was.

Then I looked up the list of types of animals who've made it to space, and it appeared to be quite varied, lots of different organisms appear to be able to make it to orbit.

Are there, however, some animals which physically couldn't/can't realistically make the journey?

Answer 1

To keep an animal alive, a spacecraft needs to create conditions (e.g. temperature, pressure, concentrations of gases or electrolytes) within the animal's normal physiological range. We can recreate nearly any environment; however, the resources necessary to do this may be prohibitive. Thus, the answer to the question is that it may be possible, yet unfeasible, for many animals.

Some examples:

• There are many animals that exist only in deep seas. Attempts to harvest such animals have often failed, as they live at very high pressures, and burst when brought to the surface. You'd need to design a container that operates from collection in the deep sea, to preparations at sea level, through the flight into space.
• Some animals are simply way too massive and voluminous. You would need a giant space capsule to keep an elephant or a whale. (Sorry, Star Trek IV.)
• Many wild animals get stressed in the small environment of a space capsule.
• If you are going to keep the animal for a while, you need to feed it. Many animals will only eat live food, so then you have to keep that alive as well.
• Every animal has limits to the acceleration they can tolerate, and some species (e.g. giraffes) need low acceleration. Getting to orbit requires reaching orbital velocity. You can reach orbital velocity with a lower acceleration, but you will then need to burn the rocket for a longer time. However, doing so requires more energy (and thus fuel, mass, and cost). That's why most rockets use as high of an acceleration that can be tolerated by the passengers and and spacecraft.
• An alternative solution to the acceleration issue would be to construct a space elevator.

If you have unlimited money, mass, and volume, then these aren't problems.

Answer 2

The two extremes are the most-likely sources of death for creatures in space - weightlessness and the g-force of takeoff.

Weightlessness could be a critical issue for any creature which relies totally on gravity for swallowing - it's likely that some bird species would not be able to properly eat or drink in space. In the long-term, it's likely that a few weeks of weightlessness won't kill many terrestrial creatures, even if it causes some difficulty.

Crushing damage or heart failure from G-force are much more likely causes of death. Small creatures are probably going to be fine - many small creatures regularly submit themselves to far higher G-force than takeoff... just by hopping around. Froghopper bugs hit ~400G regularly. Fleas hit 100G's. I'm sure house cats break 3G easily, and that's space flight. The square-cubes law helps explain this - proportionate strength makes is more likely for small things to hit higher G-force in their daily existence.

As a back-of-the-envelope calculation, since we know that humans can survive, we can assume (pretty safely) that any creature smaller than a human will probably survive the G-force of takeoff.

So what about the big boys? Elephants are unlikely to survive. An elephant at 3G is going to be experiencing ~36,000 pounds of force, although most elephants seem capable of handling roughly ~1.5G for a limited period of time - ask National Geographic about how that works. 36,000 pounds still sounds lethal to me. Giraffes would die - their hearts are already taxed by 1G. Whales are absolutely toast - they can't survive 1G out of water for long, you can forget about 3G in any circumstance. I have no idea where the line will be drawn, and I imagine that other factors matter as well... but I think that anything larger than a grizzly bear is likely to suffer fatal complications from extended 3G forces. It's just more than their circulatory system can handle.

Some creatures may be able to survive an otherwise fatal journey if placed into a gel or other liquid substance, although the container would have to be immensely strong or perhaps also serve to immobilize them (good luck building a tank that can survive an angry whale.) I don't think this would prevent all circulatory issues, although it would serve to spread out pressure and reduce damage from crushing.

Ultimately, we're unlikely to know unless we test, and I'm not enthusiastic about the ethics of the tests that would be required.

Answer 3

Lugworms living in the sand below tidal sea waters. They need gravity to burrow in and feed from the tiny animals living between sand particles. They would survive some weeks without food.

Starfish, sea urchin, sea cucumbers could not live in microgravity for longer time. They need the ocean floor to move and search for food. Starfish and sea urchins do not swim in the water as they do not have fins. Some sea cucumbers swim only for a short time.

Green Bonellia (bonellia Viridis) is another marine worm living on and partially in the ocean floor. See 1 and 2.

Those animals are part of the submarine eco system which they need to survive. They may survive the trip to space but would not live very long in microgravity.

Small air breathing marine mammals like beavers and sea otters could not swim and dive in water and then return to surface as they are used to for breathing.

Water birds used to fly in the air, walk on land, swim at the water surface and dive in the water will be restricted to fly only.

Giraffes will experience problems caused by very high blood pressure in the head during zero gravity. Narcosis on Earth is risky due to very high brain blood pressure when head and heart are on the same level in a lying position. A narcosis may be limited to an hour or less but zero gravity may be days orweeks.

Answer 4

No, because the "space" is mostly just "no gravity" but the gravity can be simulated just by rotation.

Also, any animals are unlikely to die immediately without the gravity because otherwise just turning upside down would kill them on the Earth. This is differently from human-made devices like pendulum clocks or even car engines - these are not normally designed to work inverted.

Only if we consider longer times (maybe cannot feed, maybe cannot reproduce, maybe cannot properly behave, maybe something degrades), then the presence of gravity may matter.