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## instructions

Three scientists in a space station are trying to move from the airlock to the control room pod. The hatches between pods are controlled by a button in the center of each pod. While a control button is depressed, all hatches with that letter are open; but as soon as the button is released, those hatches close. A person cannot simultaneously depress a button and move through a hatch.

Can you help our three space scientists make it from the airlock to the control room?

## example

Here are the blueprints of an example moon base:

The appropriate steps to move the three scientists (each represented by a different colored dot) from the airlock to the control room are summarized in the chart below. We'll go through this chart step by step.

The three scientists start in the room marked with the airlock hatch on the side (Room 1).

One scientist can depress the "A" button in that room, opening up the "A" hatches. This allows the second scientist to move to Room 2.

Now that both the "A" and "B" buttons are depressed, the third scientist can move into Room 4, the control room.

We're not quite done yet. All three scientists must make it to the control room. Plus, now there is a choice to be made. If the second scientist leaves Room 2 to go to the control room...

... it will strand the first scientist. They can make it out of Room 1 and into the hallway (by going through Room 3), but they cannot move through any "A" or "B" hatches to make it into the control room.

Instead, the scientist in Room 2 needs to keep holding the "B" hatches open, so that the first scientist can go to the control room.

Once the first scientist is safely in the control room, the second scientist can then move there, too.

## solving tips

Remember, this is not a competition or a race between the scientists. They must help each other, so that all three can reach the control room. You will need to think carefully about how to make progress in each puzzle, since moving scientists to rooms closer to the control room may actually move you further away from the goal. Getting one scientist to the control room is a good sign of progress, but as you can see in the example, getting the other two scientists there can still be a challenge.