Napoleon said that an army marches on its stomach and so, it seems, do astronauts. To help the crews of future Mars missions remain healthy, associate professor Dominic D'Agostino of the University of South Florida will spend ten days on a simulated space journey in a laboratory on the bottom of the sea, where he'll eat a special diet designed to counter the side effects of interplanetary spaceflight.

One of NASA's key ways of rehearsing for manned space missions is its NASA Extreme Environment Mission Operations (NEEMO) expeditions.

These "analog" missions uses the Aquarius underwater habitat, located 62 ft (19 m) down and 3.5 mi (5.6 km) off Key Largo in the Florida Keys Marine Sanctuary in the Atlantic Ocean. Since 2001, 21 teams of international astronauts became aquanauts as they spent up to a fortnight carrying out experiments as well as practicing with new techniques and technologies in the simulated weightlessness of the undersea environment.

D'Agostino, who studies the impact of extreme environments on the human body at USF, will be the only non-NASA or ESA affiliated participant of NEEMO 22 when it deploys on June 18. D'Agostino will dine on a special diet that will include ketone supplement formulations designed to cause his body to go into nutritional ketosis. This is a metabolic state where the body shifts from glucose to using fat as it primary fuel. By keeping his body in nutritional ketosis, his cells will be able to preserve their DNA from damage while he works in the stressful aquatic environment.

To provide a control, the other aquanauts will eat a regular diet as data is collected about their and D'Agostino's gut microbiome, body composition, ability to carry out cognitive tasks, vision, sleep quality, and other physiological parameters.

The hope is that such supplements will help astronauts for counter neurological risks from cosmic radiation, low oxygen, and the stress of living inside the confines of a spacecraft.