In Destiny, the Stargate vents and flashes when it closes. I don't think I've seen this happen to any other gates. Are there any reasons why this is the case?
According to the Stargate Wiki, the CO2 vents (that's what vents after the gate closes) appears to be superfluous.
That said, my own theory is that the venting is shown only on the Destiny because the Destiny is already pretty far along on it's path, and I would assume the seed ships would be programmed to discover newer and better ways to build gates, and eventually they possibly found a way to not need CO2 discharge, where the Destiny's gate didn't get the upgrades.
I'm going to go from DKuntz information, and stretch this a bit further.
So, let's start with the facts.
- The Stargate on Destiny is older than any known stargate, at least, in that part of the universe.
- The Stargate on Destiny is the only known operating one on a ship, at least in that part of the universe.
- It's common practice for ships to have higher concentration of oxygen than normal. This enables a few cool tricks, including easier space walking, lower overall weight of gas, etc. See this link.
- The gas coming from the gate is Carbon Dioxide, per the Stargate Wiki.
- We know that the gates are much more flimsy than the Milky Way gates. A shot produced a hole in one episode.
- We know that the stargates deal with lots of energy.
- While most of the gates aren't of huge importance at any one point in time, Destiny's must be more important, because it's where the Ancients wanted to land.
So, putting all of that together, we can assume the following.
- Closing a wormhole must involve large amount of energy, of a type that could potentially produce a spark.
- In order to minimize any affect, it seems likely that CO2 is forced near the gate, to keep any fire from occurring at this sensitive time.
- This CO2 spray also helps to improve the longevity of the stargate somehow, and isn't required if the stargate isn't going to be used for a long period of time.
- It could also be that the stargate is full of pure CO2 during the active wormhole, and that it's vented out after the wormhole closes, for the same reasons as above.
The planet gates are designed to only be used a few times, but the Destiny gate is designed to be used time and again, perhaps it improves the longevity of the gate to cool off the capacitors afterwards? Also, Destiny's gate is the only gate in the network that can dial an extragalactic connection, requiring way more power, my guess is that, similar to how the Icarus gate sparked from the power levels being at maximum, the older Destiny design gets really hot when powered up by a 9 chevron address, and so it was designed to vent whenever it dials, regardless... Also, I'm not sure it it vents just co2, there must be more to it, unless it's just extremely hot, because when the Lucian Alliance boarded, one member got caught in the blast after the gate closed, and either got injured or killed...