In order to collapse an unwanted wormhole you first need to identify the class of wormhole you want to collapse. Different classes of wormhole have different mass allowances, and as collapsing a wormhole relies on over-stressing this mass allowance it is important to find out the figure you're aiming to exceed. The class of the wormhole is the string comprising a single letter and three numbers that mark the entity on the entrance-side of the wormhole. The exit of a wormhole is always marked by the identifier K162 and won't be helpful. For this example I shall use the B274 class of wormhole, because the request for information came from a capsuleer who mentioned two static wormholes, so I am assuming they live in a class 2 w-space system and perhaps have a link to high-sec empire space.
There are resources available that will let you know how much mass a wormhole can pass in one trip and in total, a simple search for the wormhole class will find out. In this case, the B274 connection has a total mass allowance of two billion kilogrammes, and can pass three hundred million kilogrammes of mass through in a single jump. In order to collapse the B274 in a controlled manner it should be clear that a total mass exceeding two billion kilogrammes needs to be passed through the wormhole. For this, you'll need some big ships.
An Orca industrial command ship is handy to have available for collapsing wormholes, as it effectively pushes the maximum amount of mass through a wormhole per jump. Below that, battleships work well, but will take around twice as many trips to collapse the wormhole. As polarisation effects will be accrued, unless sufficient pilots and ships are available to make the required jumps in quick succession, the more jumps that are needed to collapse a wormhole can significantly increase the amount of time it takes. Relying on ships smaller than battleships will be an exercise in frustration and may take longer than the natural lifetime of the wormhole.
Armed with information about the wormhole you now need to calculate the masses of your big ships and determine the best sequence of jumps to ensure the safe collapse of the wormhole, so that everyone remains the right side. The fitting screen holds ship mass information, which is only slightly modified from the general information panel for the ship, accounting for the addition of fitted modules. However, one module that will come in handy is an afterburner or micro warp drive. Having such a propulsion module fitted will make no difference to the effective mass of the ship when the module is inactive, but when activated the mass will be significantly increased. This is an important tool in collapsing wormholes. The use of AB/MWDs can accelerate the initial stages of the collapse, and be used to tweak ship masses in the later stages.
With your ships ready and masses noted, both dry and with an AB/MWD activated, you can calculate how many return trips are needed to collapse the wormhole. This is left as an excerise for the reader, but I'll also use some sample numbers in a moment, shamelessly stolen from glorious leader Fin, to show that it doesn't need to be complicated. As you continue pushing ships through the wormhole it will go through some changes. The first change has the wormhole visibly shrink as it reaches its half-mass stage, where 50% of the total mass allowance has been reached. The information panel for the wormhole will indicate that its stability is reduced, 'but not to a critical degree yet'. The wormhole will also now emit an ominous pulsating sound. The second change is when the wormhole has only 10% of its total mass allowance left, causing it to shrink even further. The information panel states that the wormhole is 'on the verge of collapse'.
Look out for the changes to the wormhole's stability as you are making the jumps. Wormhole masses have a tolerance, generally considered to be around 10% of their total. This means that any individual wormhole can spawn, or respawn, with the capacity to allow between 90% and 110% of their standard maximum allowance. The visual changes to the wormhole's stability give a useful indicator to your progress and whether the wormhole may be a bit lighter or chubbier than expected. Let's look at a sample wormhole collapsing operation, assuming only two pilots and a simple pattern of jumps. Many thanks to Fin for letting me steal this information without her permission.
|Ship used||Ship mass
|Orca + MWD||300||Out||1,700||Stable|
|Orca + MWD||300||In||1,400||Stable|
|Orca + MWD||300||Out||1,100||Stable|
|Orca + MWD||300||In||800||Half-mass|
|Orca + MWD||300||Out||500||Half-mass|
|Battleship + MWD||150||Out||350||Half-mass|
|Battleship + MWD||150||In||200||Critical|
|Orca + MWD||300||In||-100||Collapsed|
Note that the Orca is sent out before the battleship but comes back after it. This is to ensure the wormhole reaches critical instability with the Orca still to return, such that the one remaining jump from the Orca will definitely collapse it. It is easier to make more jumps to destabilise the wormhole with smaller ships when there is a massive ship ready to make one final push than bringing the Orca back early and potentially leaving the wormhole on the verge of collapse. There is a relatively safe way to handle this situation, involving heavy interdictors and the vagaries of warp disruption field generators, but that's outside the scope of this post.
The above information assumes a fresh wormhole that has had merely a scout or two passing through it so far. If the wormhole has been around for long enough for unknown pilots to sneak through, or was opened by unknown pilots, or has had friendly or hostile fleets jumping through, the calculations to determine the mass still required to pass through before the wormhole collapses become more involved. In particular, if you are running operations through a wormhole before collapsing it you need to take care to note what ships pass through and how many jumps are made. A few frigate-hulled ships won't make much of a dent, nor will a couple of cruisers, but anything more could throw your calculations off, which is where making jumps with or without the AB/MWD active can help. One jump made without the MWD can account for a return trip by a cruiser, for example. If you don't know what's passed through the wormhole you can still start to collapse the connection and use the half-mass shrinking as a guide, but obviously care must be taken.
Above all, the best way to stay safe when collapsing a wormhole is to assume the worst. A known and stable connection to empire space should be available to any pilot assisting in the operation to collapse a wormhole—which is impossible to get wrong when collapsing a B274—and all appropriate bookmarks must be copied in to each pilot's nav-comp. If no route is known, battleships ought to be fitted with probe launchers, as can Orcas, although Orcas could also stuff a fully-fitted covert operations scouting boat in to their ship maintenance array. Otherwise, if the operation goes awry, or some wag sees what you're doing and jumps his own probe-fitted cloaking battleship through the wormhole at the critical moment, you may end up wishing you'd simply waited for the wormhole to die of old age, unlike your capsuleer's fate as you find you need to pod yourself back to empire space.