Typically my strategy for defeating enemies involves base defense - they walk through my turret kill room and I have a distinct advantage. This works very well for invading groups of humanoid enemies.
However, when an ancient alien ship crashes, I have to go to them to destroy the object, or face various negative effects. Once aggroing the enemies inside, they don't seem to follow me back and attack my base. If I stay and fight, my troops get slaughtered by miniguns and railguns, losing many colonists (and limbs).
How can I fight these aliens most effectively without losing half my colonists?