I’ve been reading about the food systems for space missions, which is more complicated than it sounds.

The obvious constraints: no gravity, so liquids and crumbs float away and get into equipment and astronaut eyes and lungs. Limited storage space, so food has to be calorie-dense. Long-duration missions (Gemini will go up to two weeks), so you can’t just eat sandwiches from a cooler. The spacecraft is small, cold, and has no kitchen.

Mercury used two approaches. Bite-size cubes: food packed into one-inch cubes and coated with gelatin to prevent crumbling. Squeeze tubes: puréed food in toothpaste-like tubes, squeezed into the mouth. John Glenn reported the bite-sized cubes were adequate. The squeeze tubes were less popular — something about eating applesauce and puréed meat from a tube.

For Gemini, they’ve improved the cube coatings and developed rehydratable foods: freeze-dried portions in sealed packets that the astronaut adds water to and then squeezes out. Freeze-drying removes moisture while preserving most of the flavor and nutrition, and the packets are much lighter than their reconstituted weight.

The rehydration water comes from a byproduct of the fuel cells — the hydrogen and oxygen that power the spacecraft combine to make water as a waste product. So the astronauts drink their fuel cell exhaust.

The bigger challenge is morale. Eating is not just nutrition; it’s pleasure, it’s routine, it’s a social activity. In the confined, stressful environment of a spacecraft, a meal that’s merely adequate is a small defeat for crew morale. The food engineers are trying to improve variety and palatability, but they’re fighting against the constraints of mass and volume and packaging.

The smuggled corned beef sandwich incident on Gemini 3 — John Young brought a real sandwich from a deli in Cocoa Beach — was technically against mission rules (the crumb problem) but humanly understandable. After weeks of freeze-dried packets and bite-cubes, a corned beef sandwich from a deli is pure luxury.

On the Moon, they’ll eat better than early Mercury but still nothing like home. Freeze-dried reconstituted meals, eaten in suits or with helmet removed inside the LM. Somewhere on the to-do list after the first landing: improve the food.