In the Mars Colony, shield generator area when you're on the lift, click to retun to last position and to get to the bomb. Use the maintanence key to open the hatch. Some warnings will go off and say that there are explosives in the hatch. You will need to order the wire nodes to stop the bomb. the order of the color nodes is:

Level 1: Green, Red, Yellow
Level 2: Blue, Yellow, Red
Level 3: Yellow, Blue, Green

You can't waste much time. Your time left is on the top right of the lift panel.

Here are some access codes to get you past those tricky places.

Code       Location
J689489W5  The door to get to work
J0524133   Left Command Center Screen
J0291384   Right Command Center Screen