Introduction

Scientists and engineers at the National Aeronautics and Space Administration (NASA), along with other independent scientists and engineers, have been studying how human missions to Mars might be carried out. The first missions will most likely be small with most, if not all, of their resources brought from Earth. They will probably live in small temporary living quarters and explore with smaller agile land rovers. The study was performed to explore concepts and ideas developed initially by Dr. Marvin Criswell on the subject of inflatable habitats to house astronauts living on Mars. 

Procedure

Two concepts were explored to develop generic designs for a Martian living habitat. The design process involved (1) researching previous studies performed on the topics, (2) creating CAD models of what the habitats may visually look like, and (3) performing structural analysis to investigate effects of the Martian environment. The structural analysis provided information that was used to determine internal forces and stresses in the supporting structure and the maximum displacements in the membrane. 

The sphere-shaped habitat module is the first concept investigated. When designing Martian habitats, one must recognize that the habitat will go through an extreme change in environment throughout its lifetime. It will be manufactured in the friendly environment of Earth, transported through space in a vehicle to be determined later, then constructed in the virtually oxygen free atmosphere of Mars. The idea is to use a lightweight membrane to hold internal pressure and a lightweight composite material to provide structural integrity. To keep costs as low as possible, and to fit spacecraft size constraints a low overall stowage volume for the habitat is desired during transportation. But larger living quarters on Mars are wanted. One solution to this challenge, along with the associated problem of outfitting the living space, is to use habitat modules having a strong inner core where all the materials necessary for construction can be stored within during transportation. Then once on Mars surface, astronauts can unpack the membrane and other supporting elements and assemble them.

The second concept was actually developed first and has been the subject of several studies.  It is called the tufted pillow concept.  The idea behind this inflatable structure concept includes structural members formed from a high strength membrane in the shape of a tube.  The tubes are inflated to a high air pressure giving them structural stability.  These tubes can then be placed in a manner that is similar to columns or arched beams.  The tubes make up the supporting structure, and the same membrane used in the tubes is also used for outer walls making the habitat airtight.  This concept has been presented in several previous papers and in this study is just modeled in AutoCAD to provide improved visualization.

The AutoCAD modeling and AxisVM analysis study was very beneficial visualizing in the general behavior of the rather unusual structures under study.