Man cannon
From Halopedia, the Halo wiki
The Man Cannon device tosses a player through the air to another part of the map. The user is said to be unprotected while in mid-air, but can still attack other players. It is much like the Covenant's Gravity Lift technology, possibly the Covenant learned this from the Forerunners. The Man Cannon works as a kind of replacement for the teleporter, but the teleporter may still exist in other maps yet shown.
While the name specifies a man, the cannon will launch anything that enters it. Unfortunately, its strength will be diminished on heavy objects such as Warthogs, and not launch them as far.[1]
As of now, this device has only been featured in the Halo 3 Multiplayer map Valhalla, but a similar device can be found on the Halo 2 Multiplayer Map, Ascension.As shown in the new Halo 3 Vidoc,Bungie create the Man Cannon to replace the teleporters because it adds some challenge to the gameplay because it has side effects when using it,unlike the teleporter. For example,the player may be snipe while in mid-air but still can attack other players.
