Americans love rockets, and their interest focuses on the two ends: the front end where the astronauts sit and the tail end where the rocket engines are bolted. For decades, NASA has kept the focus on the front end through an unrelenting public relations campaign touting the astronauts' importance. While this is understandable, it has unfortunately resulted in a skewed program where the Space Shuttle and the International Space Station—both based on old technology—get most of NASA's budget. It's time to seriously work on the tail end again and build advanced propulsion systems. If we don't, space endeavors will be stuck forever in low-Earth orbit, doing no better than struggling to bolt together the space station. The station is supposed to provide information needed before sending humans on long space voyages, but we already know that living in space is essentially bad for people. It is debilitating to bones and muscles, and radiation from the solar wind and cosmic rays can cause cancer. To go to Mars or back to the moon with slow, low-powered chemical rocket systems is asking for trouble. The best a chemical rocket can do is get up to speed (burning up all its propellant in the process) and then drift to its destination, like a car coasting down the highway with its engine off. What's needed are space drives that will provide a controlled velocity.
Spaceflight should evolve in much the same way as the exploration of Antarctica. The first expeditions to the South Pole in the late 19th and early 20th centuries were essentially sprints and publicity stunts, carried out primarily for national prestige and personal glory, though often wrapped in the dubious veneer of science. These sprints were accomplished with the technology of the day—steamships to the ice shelf followed by the use of dogs and manpower to make the tortuous journey. Many men died and many more suffered from frostbite, hunger and exhaustion.
After Norway's Roald Amundsen and Britain's Robert Scott both reached the Pole in 1911 (with Scott's party all perishing on the way back), interest waned in duplicating their feats; it was far too expensive in both money and blood to do something that had already been done. Four decades went by before the next explorers arrived at the pole. They were Americans, and they simply flew there in an airplane.
It will be the space equivalent of this airplane that will carry people back to the moon and to Mars and beyond. But what kind of engine will power it? I believe it must be a nuclear fission rocket—if we're to see it in our lifetimes.
A fission rocket is a simple and safe system that uses a nuclear reactor to heat up a liquid such as hydrogen to create thrust. Unfortunately, "nuclear" and "fission" have been dirty words in this country for the last three decades. Despite the fact that nuclear propulsion is the best and safest way to fly major missions beyond Earth orbit, NASA stopped its development back in 1972 to put nearly every penny it had into the development of the shuttle. That was a terrible decision. At that point we had successfully tested nuclear rockets in the open air in Nevada, engines that could be operated with high thrusts for long durations—the key to entering the solar system.
It's time to resurrect the nuclear rocket and confront the critics of nuclear energy, one of the cleanest forms of energy known. Hundreds of nuclear reactors are tooling around in the world's oceans right now, propelling submarines and aircraft carriers. Newer designs, including SAFE—the Safe, Affordable Fission Engine—are now being developed at NASA's Marshall Space Flight Center in Huntsville, AL.
But why send humans beyond low-Earth orbit at all? One word: energy. The low energy costs Americans currently enjoy are due to the abundant supply of fossil fuels. When those eventually go away—and they will—our advanced society may well collapse, unless we take the steps to prepare alternative energy sources. Wind, geothermal, tidal and solar energy resources can be added to the mix, but they will never supplant fossil fuel energy. For that we need something big. Only a combination of nuclear and space-based energy resources can ever take the place of fossil fuels.
The solar system is filled with energy in a variety of forms, including solar energy, which could be microwaved back to Earth, and the isotope known as helium-3, which happens to cover the moon. Helium-3 may be the key to fusion energy; many energy researchers believe that fusing helium-3 with deuterium is the cleanest and cheapest approach to commercial fusion power.
In my book Back to the Moon, I forecast a day when we'd desperately need that isotope but would lack the means to get it quickly without tremendous risks. I hope my forecast is proved wrong. But right now, it would be nearly impossible to organize new human missions to the moon on a short time-scale.
NASA should devise a 15-year program to produce a working advanced space propulsion engine. Our elected representatives and the leaders of NASA should move in concert immediately to put this engine in the agency's budget, with a fixed schedule to build it. It should take a far higher priority than the space station. If we can just get our first advanced rocket booming around space, there will be no holding Americans back from the next frontiers.
