Imagine doing nothing but lie in bed for approximately three months without a medical reason. You will probably end up losing your job and worrying your friends and family. Unless you do it for NASA — in which case, you may end up nearly $15,000 richer.

NASA’s Human Adaptation and Countermeasures Division (HACD) is charged with performing biomedical research to determine what effects space travel has on people — with a particular focus on the effects of a prolonged exposure to an environment with very little gravity. Some of the experiments occur (or occurred) on the International Space Station or aboard one of the U.S. Space Shuttles, but some studies use civilians on the ground back here on Earth. One, in particular, had a simple goal: determine what happens to astronauts if they spend months on end in a microgravity environment.

To simulate this, in 2008, HACD brought six civilians to Galveston, Texas, just an hour outside of its headquarters in Houston. The six guinea pigs were given special beds tilted at a negative six degree angle. They could read books, watch movies, listen to music, etc. But there was one thing they could not do: get out of bed.

The conditions, described by participant Heather Archuletta in an interview with SmartPlanet.com, were extreme, designed to mimic the effect of a three month stay in an area where the weak gravitational force kept you in such a condition. The test subjects were not allowed to nap — HACD would play wake-up music at 6 A.M., and expect those being observed to remain awake until, colloquially (but hardly apt here), bedtime. Bathrooms were replaced by bedpans. Showers were replaced by a laying-down experience on a mesh gurney, in order to preserve the participant’s near-horizontal angle throughout the 90 day period. Each participant’s diet was closely monitored, in order to maintain their weights within a desired range.

Of course, the subjects were monitored closely — daily weighings, regular sonograms, and similar tests. But Ms. Archuletta did not need the tests to tell her that she was going to get more than she bargained for — she was in such whole-body discomfort that even her molars, which had dental fillings, were throbbing just a few days in.

For their trouble, participants were paid $160 a day — $14,400, had the experiment run the full 90 days. But when Hurricane Ike forced the evacuation of Galveston, the experiment was cut short at day 50. The effects of the experiment were no less extreme, however. Ms. Archuletta and her fellow pseudo-astronauts suffered from lower bone density, weakened muscle mass, changes in their blood chemistry, and certainly many other untold maladies. They were taken by ambulance to a hospital in Austin to recuperate. In total, Ms. Archuletta told SmartPlanet that her recovery took about a month.

HACD’s test are on-going. As of this writing, there are listings on their webpage, here, for candidates for two other studies. One is a 70 day study to investigate the effect of high intensity interval-based aerobic exercise as a countermeasure to the problems Ms. Archuletta experienced. The other, similarly, explores a possible countermeasure; it is a 14 day study using compression garments as the potential solution. Up for the challenge? If you are 24-55 years old, in good physical health, and a non-smoker, you may qualify.

Bonus fact : Want to avoid gravity just like an astronaut — but not by subjecting yourself to 90 days in bed? The Zero G Corporation travels around the U.S. to provide an 8-minute weightlessness experience (over the course of about a half hour), but it will cost you $4,950. Here’s how it works.

From the Archives: Mission to Nowhere and Mission to Not-Quite Mars: Two other experiments which focused on exploring the universe, without leaving the ground.

Related: “Go the F**k to Sleep,” by Adam Mansbach and Richard Cortes. A children’s book for grown ups, 650 reviews, averaging 4 stars.