Title: Planetary Airlock and Suitlock Requirements and Alternate Approaches
text: This study describes the operational requirements for planetary surface access and compares the performance of a hatch, airlock, suitlock, and suitport. The requirements for mitigating dust, performing EVA (ExtraVehicular Activity) by only part of the crew, and use on Mars as well as the Moon are strong reasons to prefer an airlock over a simple hatch, which would require depressurizing the habitat and sending all the crew on EVA. A requirement for minimum cost would favor the hatch above all. A suitlock provides better dust mitigation than an airlock, but at higher cost and complexity. A suitlock accommodating two crew meets requirements for buddy assistance and ability to help an incapacitated crewmember. Two suitlocks would provide redundant airlocks. A suitport, similar to a suitlock but having a suit-bulkhead pressure seal and no outer airlock door, provides dust mitigation and operational flexibility similar to the suitlock at lower cost, but increases risk and limits contingency response. A combined airlock/suitlock/suitport has the broadest capability and flexibility.