maybe already suggested before.
extraction:
extract the vip from the asteroid base, slightly forward of the enemy spawn, and carry them back to your asteroid base. actually put a dock port on an asteroid which you have to fly into and pickup the vip. to get away from the beacons theme. if the enemy intercepts the vip, and ‘picks him up’ he is automatically returned to base like a flag in CTF modes. in fact, it is like a CTF mode with some RPG elements.
excavation:
protect one or two players on your team who act as ‘miners’ and must sit near 2-3 groups of pre-defined asteroids to mine material, then haul it back to a friendly beacon. the more material they acquire, the slower they become, and must be properly escorted. also, make each group of asteroids depletable, so eventually only one or two will be contested. sort of like a ‘warcraft peon’ mode… er simulation if you will… ;\ the asteroids could be destructible to begin with, to force a buffer before they can be contested.
another idea is to instead make them into dense pockets of gas. sort of like nebulas/clouds. which obstruct vision, and slow movement of any ship inside by 50%. when any ship (not just 2 predetermined ships on the team) reaches the center of the gas deposit, they start collecting gas, and must then exit the cloud, maintaining their 50% reduction and haul the cargo back to base, escorted.
infiltration:
infiltrate a cloaked science station by first disabling a jamming relay network scattered throughout enemy territory. the jammers would be aligned in a grid (think of it as the homeworld cataclysm mode), 32 jammers into total forming a grid wall. take out 24 of these jammers to reveal the enemy station, then destroy the enemy station (not capture).
devastation:
destroy/bomb a large enemy complex armed with gun batteries and defense mechanisms. although this might be ‘dreadnought’ mode. then again that could be escort the dreadnought, who knows for certain. or what this dude suggested with critical systems: [http://forum.star-conflict.com/index.php?/topic/21016-new-game-mode-assault/](< base_url >/index.php?/topic/21016-new-game-mode-assault/) and make it so taking certain sub-systems out reduces certain aspects of the object’s effectiveness. even having those modules provide small system-wide environmental effects for their team.
destruction:
an enemy ai convoy is moving through the region. the team which destroys the most cargo frigates (high HP) wins the match. several variations: each side has their own ai convoy to protect, or a single convoy moves through the center of the map in single file, spawning at one end, despawning at the other. in the second scenario, you would have to pick up the cargo after destroying the vessels and haul it back to a designated dropoff point/collection facility (no beacons please).
exoneration:
continuing the trend of game modes beginning with ‘ex’… whoever draws first blood become the ‘target’. he scores several points for his team. the objective is then to kill this target, which nets the other team points and his killer becomes the target. a game of ‘tag’. 
of course, target kills would have to just count for a certain number of kills/points with each regular kill counting for 1 point, as opposed to them determining the outcome of a battle, since the last team to hold can shut the opponents out. deathmatch with a vip. or just make the vip the player with the highest score/kills/assists.
excommunication:
hehe. still thinking…
combat recon:
yes, this is the same as the old mode… but… the enemy who kills your commander, becomes the enemy commander. hahaha. rofl. 
beacon hunt:
the respawn mechanics needs to be removed or revised, it can completely break games when abused or when your team is unaware of them.