The Gravity Mines are a special weapon of the game Star Trek: Armada. When used, a mine is ejected from the casting ship, that will target an opposing ship in its vicinity. If no ship is within reach, it will stay still. After impacting a ship, it will reduce that ships movement speed noticeably. Gravity Mines do stack, so every additional mine will slow down the ship even further. It the mine is not attached to anything (even when in the process of approaching a target) for too long, it will disappear. The mine can be ejected even when under cloak. It is researched at the Weapons Center. It looks like this:

The slow-down of one mine looks like this:

The ship in the upper left corner of this group of Bird of Prey has one mine attached to it. If a ship has at least one mine attached to it, a small symbol is added to its wire picture:

Gravity Mines also target cloaked ships, decloaking them on impact.

The deceleration is calculated like this:

newWarpSpeed = (oldWarpSpeed - impulseSpeed) * slowPercent / 100 + impulseSpeed

with a slowPercent of 50. As all ships have an impulse speed of 20 the general formula changes to:

newWarpSpeed = (oldWarpSpeed - 20) * 0.5 + 20

The effect does stack. So the 0.5 is actually applied as many times, as mines are attached to a ship. So four mines will end up slowing a ship with warp speed 100 to:

newWarpSpeed = (100 - 20) * 0.5 ^ 4 + 20 = 25

As you can see, the value will never drop below the impulse speed (20). An active Corbomite Reflector has no effect on this special weapon. Neither does the Shield Remodulation. The Phase Cloak does protect from it.

When repairing an affected ship in a ship yard, the mines are removed.