BA.
… the part of a massive body in which a mass defect was created is usually called fuel (chemical, such as methane with oxygen, nuclear, such as uranium or plutonium, thermonuclear, such as deuterium with tritium). From the point of view of fundamental knowledge, the difference is only in what part of the mass is converted into energy (up to 0.7 percent of the initial mass). The common thing is that the fuel is not what the recipient of the cargo should receive and that the fuel can and is used only once. And if from carbon dioxide and water it is possible in principle to obtain methane with oxygen again, then from radioactive fragments uranium cannot be collected back, just as deuterium with tritium cannot be obtained from helium and neutrons. That is, the number of relatively fast flights (even inside the Solar System) is significantly limited. Although it is possible that in the future there will be orbital factories using the energy of the Sun to synthesize transuranic elements. In any case, the flight of astronauts during their lifetime even to the nearest stars is impossible. And therefore uninteresting, so we move on to …
C
Creation of a temporary mass defect that does not violate the connections and structure of the material body, the number of particles forming it and their properties. That is, the number of electrons, protons and neutrons (nucleons in the nuclei of atoms) in a massive body remains unchanged. The creation of a temporary mass defect has at least two obvious advantages compared to the creation-use of an ordinary mass defect. The first advantage is “free” braking. That is, the creation of a temporary mass defect means giving a non-zero speed to the material body, the cancellation of a temporary mass defect means returning the body to zero speed – braking and a complete stop. The second advantage is “fuel reusability”. That is, at the end of the flight (discontinuation-flight by inertia-braking), multiple creation of the same temporary mass defect is again available. Fundamentally, there are two options. Either “heavy” mass must be converted into normal mass, or normal mass must be converted into “light” mass. Each method has its advantages anddisadvantages. Each of the options will be discussed in detail in the next message