Astronauts may soon be making fresh sandwiches in space thanks to a new process. The concept uses the carbon dioxide naturally expelled by the astronauts expel to act as the leavening agent, eliminating the need for yeast. The carbon dioxide is mixed with water in a sealed, pressurized chamber, where it dissolves to form carbonic acid which is then combined with the bread dough in a separate sealed container. Releasing the pressure in the sealed container converts the carbonic acid...