Deck four contains officers' quarters and the vessel's medical facility.

Crew Accommodation

Crew accommodation configured for officers make up the bulk of the secondary space on this deck, including quarters for the commanding officer and executive officers.

VIP Accommodation

Two VIP suites are provided, each with nearby accommodation for staff/aides.

Mission Configurable Area

Two areas forward of the firewall are configurable for specialist mission requirements, surrounded by removable bulkheads.

Each area can take up to 10 cargo pods configured to mission requirements when combined, such as labs, instrumentation and specialist accommodation or cargo. Alternatively, the spaces can be used free-form as overflow accommodation, storage or even event spaces.

Sensor Equipment

Sensor equipment additional to that on deck 3 is located at the outer edges of the forward section. A hatch and ladder links the deck 3 and deck 4 sensor equipment areas for repair and maintenance purposes.

Wardroom

Forward of the firewall is the wardroom, a formal space used for official and diplomatic meetings, functions and dining.

The wardroom includes a small kitchen used to heat and present food previously prepared in the galley, and a bar.

While the wardroom is traditionally the primary dining space for officers on board naval vessels, on Endeavour officers dine in the mess deck with the rest of the crew.

Engine Room

Primary access to the vessel's Magnetoplasma Impulse Engines is from aft of this deck, including the plasma generators that supply the engines.

A small personnel lift and two ladders provide direct access to the engineering areas on decks 4 - 7.

MIE CAR

A Central Apparatus Room (CAR) for impulse engine control equipment is accessible from this deck.

Sensors

Sensor equipment is located on each side of the citadel.

Sensor Data Centre

The main data centre for processing sensor readings is located on this deck.