Fusion for Space Propulsion

The possible role of a controlled thermonuclear reactor in space missions is discussed. Although such a reactor is many years from reality, some of its properties are understood well enough to indicate problems which will appear and which are peculiar to space flight. It appears that it will have to deliver electric power or thrust at a weight of about one pound per kw in order to represent significant improvement over other systems, notably the fission-electric one. One attractive feature of a fusion reactor, as now envisioned, is that it may lend itself to the direct production of electricity or even thrust, without an intermediate heat cycle. It is essential to avoid such a cycle if the weight is to be kept low.