Designing the most plausible space "dwelling" planimals

Question

I'm a scientist of a colonised alien world in the far far future, on a planet which plant-derived insects and meat trees are keystone species in their biospheres. Let's say, I wanted to genetically engineer these plant-insects, let's call them microdecapedes for now, to survive in space for about 3 hours: how would I go about that?

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Their biology and evolution

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(pictured above is the species I would like to genetically engineer)

Evolution

These animals originated from seed-baring trees, which originally had muscled seeds which looked much like worms which would move along the ground like a caterpillar. Due to competition, these seeds became exceedingly complex, being able to locate other pseudo-seeds using pheromones. This species however, has lost their plant stage in their life cycle through neotony completely. Leaving us with the cosmopolitan, 10 legged, hermaphrodite plant-insect we see today.

Biology

These creatures rarely exceed 10 centimeters in length, altough they do live in an oxygen rich (25%) world with less gravity (72% that of earth). They lack lungs, and instead breath much like insects on earth, through the spiracles running along the sides of their body which can be closed and opened. They lack eyes, or even a proper brain, so instead rely on pheromones to locate one another. They have light-sensitive skin spots all over their bodies to find suitable locations with which to lay their eggs in. These creatures also lack hearts, and use haemolymph once again, much like insects on earth. Their skin is made out of the same stuff as plants, not utilising chitin. They're frugivorous and eat through their mouths positioned in between the sensory organs near their heads. They're hermaphrodites, having a vagina on their chin and having a penis-like organ on their chests which they mate with. They have a hydroskeleton like spiders used to power their legs. On avarage they range from 4-7 cm in length.

The question

How would I, a future scientist with incredibly advanced technology, need to engineer microdecapedes so they could survive and perform basic tasks such as move its legs, in the vacuum of space for 3 hours, no matter how different it would be from the original species?

Answer 1

The biggest problem is conserving internal pressure against the pull of the vacuum of space. The creature needs to carry all the resources for it's continued function with it into the vacuum, that means holding on to water and oxygen against the pull of an environment more devoid of pressure than any we can produce on Earth. It's not just the lungs that have to seal either, it's all the creatures' orifices and the outer membranes of all the surface cells that make up its skin.

They'll need something like a nictitating membrane made of hardened glass if they want to use their eyes in vacuum. Armoured skin that doesn't breath at all, like the carapace of a bug but without any pores at all while in space. That is going to effectively form an exoskeleton (but it is going to have to be more rigid than any insect we know of because of the way the edges vacuum lock together) enforcing certain restriction on motion. The lungs and trachea will need to be able to pinch off, or it is going to have to store oxygen in saturated tissues/fluids for the duration. If the creature is small enough to use spiracle breathing these opening are far smaller and thus easier to seal as they have less total pressure on them at any give pressure differential. If it has to have lungs then book lungs might be superior in terms of survival in the event of a decompression event. It may be worth looking at some of the information floating around the stack on non-oxygen metabolic processes some of them would render a gas seal unnecessary as they deal entirely in solid and liquid metabolites and waste products. Sealing the throat and anus will also be of paramount importance to keeping the insides on the inside where they below.

Provided that a vacuum seal is possible exhaustion is going to be the biggest issue. The first issue being heat build up, in space you lose the two most efficient mechanisms for dumping heat away from the body, conduction and convection. Conduction is impossible in a vacuum because you aren't touching anything and convection is impossible because there is no fluid medium to move, also you don't want to sweat when you're supposed to be sealed against fluid (both gas and liquid) lose. At it's most extreme heat exhaustion causes your organs to literally melt inside your body. The second is going to be exhaustion of chemical energy reserves, this means both fuel (food/fat reserves etc...) and oxidiser (oxygen or other). Bigger bodies burn energy faster than small ones but also have greater volume for reserves so that is something of a balancing act.

You'll need to look carefully at the tasks you want your creature to perform and carefully tailor it to be the minimum size to accomplish those tasks to achieve maximum biochemical efficiency. Then work out your metabolic base, whether your going to have a gas breather or a creature that a uses solid/liquid-liquid, solid/liquid-gas, liquid/liquid-solid, or liquid/liquid-gas metabolic process, I would suggest that a waste gas has potential as a propellant. Find a base organism and make the alterations necessary.