A crane lifts them into the pool, wearing 300 pounds of space suit apiece.
Underwater, the safety divers meet them and carefully remove them from the platform.
Each astronaut is carefully weighted to be precisely neutrally buoyant.
(Hey, they don’t call it the Neutral Buoyancy Lab for nothing!)
Once weighted properly, the astronauts hover in the water as if floating in the weightlessness
of space.
Since fins don’t work in space, the astronauts don’t get to wear them here.
They must be moved from task to task by the divers.
The divers are also responsible for keeping a careful eye on everything happening.
Each astronaut has 4 divers assigned to him or her.
Two are safety divers.
Another has a camera with a cable going to the control room.
And there are more cameras mounted all over the inside of the pool too.
In the Test Director room overlooking the pool, 21 monitors keep the staff informed
of everything that happens below.
They oversee the safety of the operation.
If anything were to go wrong, the divers can get the astronaut to the surface in only seconds.
In the Test Conductor room, another team is conducting the training run.
The test conductor and team speak directly to the astronauts through communication gear
in their helmets.
But powerful underwater speakers allow the divers to hear everything that is being said,
even if they can’t talk back.
The point of all this effort is to provide a learning environment for astronauts where
they can practice tasks over and over in simulated zero gravity, before they are required to
do it by themselves in space.
Tasks that are easy on land become much harder in zero gravity.
And harder still while wearing a space suit that has to be able to protect an astronaut
from the vacuum of space.