Space Mountain is one of the safest attractions in all of Walt Disney World. Most Cast Members in the area refer to it as Breakdown Mountain and check-in on Facebook at Breakdown Mountain when it goes down. Leaders, coordinators and Space Cast Members consistently go through Breakdown Classes and trainings. When Space goes down, it is usually caused by the guests.
The most common breakdown usually happens at unload. During a busy day, rockets come as quick as 21 seconds between each other. If guests are slow or need extra time to exit the rocket, there will be a backup of rockets at the station. After a couple of rockets getting backed up, the ride will have an automatic emergency stop because the rockets will eventually be too close to each other. This will have the shortest amount of downtime, usually just over an hour.
When this happens, the coordinators need to dump the queue. After the queue is empty, the Cast Members at load will reset the ride on both A Side and B Side and they will RAC out and begin track walking. Once the Cast Members meet up, they will then begin to cascade the rockets. Cascading the rockets means manually pushing them to the next zone and eventually to unload. This needs to be done for every rocket on the track.
If there is a 104 party (wheelchair party,) Space Cast Members may need to contact the fire department, Reedy Creek, to assist with the evacuation. There is an elevator inside Space Mountain on B Side, the side we send guests with disabilities. On a related note, the top of Space Mountain is an extendable roof and can open in the event of a Signal 25 (fire) inside the mountain.
Another common breakdown is when a guest drops something on the ride. If it lands on the track or passes through an intrusion sensor, it will trigger another emergency stop. The closing track walkers at the end of the night will be able to retrieve the item that was dropped. For this, Ride Access Control procedures must be taken and Cast Members will have to make sure everyone is still seated in their rockets and figure out what caused an intrusion in that zone. They then have to cascade the rockets, etc.
Occasionally, Cast Members inside the tower can cause an issue. Sometimes it is a station stop, guest standing up or even a guest getting out of their rocket. Once, a Cast Member advanced a rocket without seeing a hand signal from another Cast Member signaling he was about to cross the track. The restraint Cast Member hit the E-Stop just in time, as a Cast Member could have been seriously injured. Oddly enough, Space will always go down whenever a certain coordinator steps foot in the mountain for the first time in a while.
Also to note, if one side goes down, it affects both sides. Other attractions like Tower of Terror have separate ride systems for each side, but Space only has one. If Reedy Creek needs to be called, Space can be down for 3-4 hours. If it is only a minor issue, it should be up about an hour and a half later.