In the red-rock desert west of this lonely little town, six seriously smart people are living in something that looks like a sawed-off corn silo and smells of unwashed socks. They go outside in white canvas space suits trimmed in duct tape. Their helmets are made from plastic light fixtures and white bullet-shaped trash-can lids. In their habitation module (the thing that looks like a silo), they sit with their laptops late into the cold desert night, typing up reports of simulated Mars disasters. The not-so-deadly pretense of living on the Red Planet while hanging out in a tall tin can in southern Utah is the latest wrinkle in a private plan to persuade the federal government to send humans to Mars sooner and for less money than envisioned by the National Aeronautics and Space Administration. The Mars Society — a group of about 5,000 dues-paying Mars enthusiasts from 29 countries, many of whom are space scientists and some of whom work in senior positions at NASA — wants to send men and women to Mars within the next decade, at a cost of $10 billion, far below previous space agency estimates.