The Essential Services button is used to reduce Alpha's power to minimal life support capacity. It is hidden behind a hatch in a computer panel. The panel, and other closely related switches, are located at various points around Alpha.
The "Auxiliary services only" button in Main Mission is seen in Guardian Of Piri, and the "Essential services only" in Computer Room is seen in Space Brain. The function is also run in Black Sun but the button is not seen. The "Atmosphere Control" is seen in One Moment Of Humanity. An unidentified power button is seen in the Power Room in The A B Chrysalis. A "Destruct" button is seen in Voyager's Return. The "Do Not Open" dial is seen in the Nuclear Power Station in Earthbound.
Earthbound: this hatch opens the concealed life support core in the Nuclear Power Station. Here the hatch is labelled "DO NOT OPEN"
Earthbound: there is a dial rather than buttons
Auxiliary Services in Guardian Of Piri
Voyager's Return: the self-destruct button on the Voyager class of spaceships. The label is "DESTRUCT".
Voyager's Return: note the panel is upside down here.
Space Brain: the Computer Room Essential services button
Space Brain: the text reads "Computer Master Switch", "Essential Services Only".
Space Brain: Koenig activates the programme.
One Moment Of Humanity: the hatch closed.
One Moment Of Humanity: a good close up. To depressurise Moonbase Alpha, press the middle button.
One Moment Of Humanity: otherwise this is the same panel.
One Moment Of Humanity: When Tony switches it back on (using the down arrow, not the "on" button), the yellow light comes on.
The A B Chrysalis: in the Power Room, it is now the "Power Control".
Copyright Martin Willey