Air grenades - where you should stop worrying about the science

I had a great idea for a grenade that had super-compressed air in it. When it "explodes", it's harmless but lets out enough breathable air to pressurise a sphere 5 metres in diameter. What a great non-lethal device! Pair it with a portable Gravlock (a bubble that keeps the air in) and you have a vacuum-to-survivable bubble in a second (Byrn's idea back in 2006). Got the airlock shut but no pressure? No problem! WOOMF! You have pressurised air.

Step up Byrn

Long standing Icar legend, memoriser of the rules, mathematician, cyberneticist and excellent friend then hit me with the science and my lovely idea unravelled.

Here's his reasoning.

A 5 metre diameter bubble has a volume of 62.5m³ Air density at 1 atmosphere (sea level on Earth, nice and comfy) 1.2kg per m³ Therefore, the air of a 5m bubble would be 75kg mass or roughly 750N.

So my pressurised grenade would be the same weight as a human. Probably too heavy to pop on a utility belt! Byrn tried to come to the rescue.

Use pure oxygen at 0.2 atmospheres. That's the maximum partial pressure (PPO2) of oxygen that divers need to survive. Oxygen at 0.2 atmospheres is 0.26kg per m³. For our air bubble, that's still a 16kg grenade.

Byrn also calculated that a single person could use that oxygen up in 4 hours if they were working really hard or 23 hours if at rest. The more people in the bubble, the shorter the time.

Pseudoscience possibilities?

Icar has a pretty stable science foundation for its technology. All matter can be represented with an energy pattern. The more complex the matter is, the more difficult the energy pattern is to make. You can store energy patterns in other materials (this is how generators and food processors work) and then use a little energy to unpack the larger stored energy into something else.

So, the grenade could be filled with a special material that turns into a large amount of gas. The problem with introducing this new material into canon is that you need to see what the knock-on effects of this are. What else might this gaseous material be used for?

Icar is a space opera

Space operas are not hard science fiction. I accepted that a long time ago. For the game to be fun to play, you have to run rough-shod over some physics. As a GM, I have to remain as serious as possible or the players will have no suspension of disbelief. If there is anything too outlandish, then everything breaks down too fast. I think air grenades are OK, so they will be making an appearance!