Further studies refined the concept, with an initial configuration to be fitted with five ejector seats, for four passengers and one crew, rather similar to the first four Space Shuttle spaceflights. Once the passenger module is fully certified, the ejection seats will be removed and there will be 16 upright seats installed for a short stay in space (<14 days) and 4 supine seats for long stay in space (>14 days). An upright seat will also be provided for the crew. There are also life support systems under the cabin floor, equipment bays, and cargo holds.