Another way to phrase this question would be to ask, «How much does a person eat in two years?» Based on data from previous and current missions to our planetary neighbor, a trip to Mars could take six months to get there and six months to get back. So if you plan to stay a year on the planet to conduct your research, you’re looking at a total of two years for your interplanetary trek.
A typical male who weighs 200 pounds (91 kilograms) and is getting some exercise needs the following on a daily basis:
83 grams of fat
60 grams of protein
25 grams of fiber
A wide assortment of vitamins and minerals
A typical female requires less of everything, so this way we know we’re covered.
We can assume that the food can be supplemented with vitamins and minerals (either mixed in or as tablets), so there’s no need to worry about that part of the equation. The whole problem comes down to calories, protein, fat and fiber.
If you want to be a minimalist about it, you can get your calories from white sugar, your fat from vegetable oil, your protein from protein powder and your fiber from bran. In this case, each person on the two-year journey would need:
602 pounds (274 kilograms) of sugar
133 pounds (60 kilograms) of vegetable oil
96 pounds (43 kilograms) of protein
40 pounds (18 kilograms) of fiber
If you formed all of those ingredients into bars or kibble, you would need about 880 pounds, or 400 kilograms, of food per person. When you buy dog food at the grocery store, a typical large bag holds 20 pounds (9 kilograms). So you would need 44 large dog-food-sized bags to keep one person alive for two years.
The other thing a person needs is water. On most space missions, water is a byproduct of electricity production in fuel cells, so it’s not a big concern. Nutritionists recommend that you drink at least eight 8-ounce glasses of water a day. Let’s say you might be a tad thirstier. So for a two-year mission, a person would need about 456 gallons (1,726 liters) of water.
Let’s hope we get the opportunity to break bread on Mars someday.