Rockets, Missiles, & Space Travel: The up-to-tomorrow story of rocket development and space-travel prospectsby Sam Dinkin
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| It may be surprising to remind ourselves that some of the radical predictions came true and we are still waiting on some of the conventional ones. |
This prediction Ley and Oberth got very, very right. This anticipated spy satellites, weather satellites, TV and telephone communication satellites, and navigation satellites. It anticipated Sputnik, the Cuban Missile Crisis, and even the need for Galileo despite having GPS. It did not anticipate the unmanned part.
I was amazed to find that the whole arc of the first 60 years of space exploration was anticipated by von Braun and Ley:
[von Braun’s] attitude is that only an expedition [to the Moon] of several dozen people who are experts in various sciences would learn enough about the moon to accumulate the knowledge required to decide what should be done in the future. The moon may even offer so little that the first visit will also be the last—at least until the time when a trip to the moon might be made just for amusement… (p.384; editorial notes added)
Fifty years later, we find that we stopped visiting the Moon a few years after we started and that Space Adventures in conjunction with the Russian Federal Space Agency and Energia are offering tourist trips around the Moon for $100 million a seat, double occupancy. We will see if “amusement” has more staying power, innovation, and cash behind it than science, exploration and national pride.
…or conditions may be such that a lunar observatory and a lunar base may be established. To astronomers the idea of an observatory on the moon is most enchanting, but they are comparing it with observatories on earth which have a never-ending struggle with a dense and capricious atmosphere. An observatory near the space station might do just as well and would be far easier to reach. (p. 384)
The economics are even less compelling now given that the “never-ending struggle with” the atmosphere has ended with adaptive optics, artificial sodium star images, and wave transforming image processing. Putting up a spinning mylar sheet at L-2 (far side of the Moon) can make a permanently cold spot with no light from the Earth, the Sun or the Moon.
| We will see if “amusement” has more staying power, innovation, and cash behind it than science, exploration and national pride. |
The Moon does have some things going for it. Getting radio quiet on the surface of the far side of the Moon is advantageous—at least until there is sufficient commerce on the Moon to make it as loud as the rest of the Earth-Moon system. The scientific benefit of being far away from radio chatter dissipates the economic benefit of being close to maintenance personnel and vice versa.
…after the manned space station has been built, after the moon has been circled, and after the planetary probes have been sent out—will spaceships still be powered by chemical fuels, even very advanced chemical fuels like fluorine-oxygen mixtures tearing apart the molecules of very specialized hydrocarbons? In short, how about atomic energy? (p. 398)
Fluorine-oxygen and exotic hydrocarbons are out of favor due to handling, design, and storage difficulties. Nuclear thermal propulsion is still in the future.
…a rocket might be powered…by having an atomic reactor run at a very high temperature and by heating a ‘working fluid,’ like water or, better, liquid hydrogen. But even to match exhaust velocities with the best liquid fuels would require temperatures so high that they cannot yet be handled.
However, there is one other way known—the so-called ‘ion rocket.’ The basic idea is rather simple. Take an atomic reactor, produce steam to drive a turbine, couple the turbine to a generator which produces electric current, and use the current to ionize a working gas which is exhausted with an exhaust velocity far surpassing anything any chemical fuel can produce. Theoretically possible. Ant it probably can be made to work. But while the exhaust velocity would be enormous the mass of the exhaust would be small, very small. A ship of a mass of several tons would operate with a thrust of a few pounds; on the average, it appears, one-half pound of thrust per ton of ship’s mass. This thrust would be steady, and in time it would produce considerable velocities—but only if the ship is in space to begin with, having been assembled in the vicinity of the space station.
There are various proposals for such ion rockets. There is even an official project for a study of the ion drive. But this, to repeat, is in the category of ‘breakthrough,’ and breakthroughs are unpredictable. One cannot just bring them about. And even when one is working for such a breakthrough, one cannot predict when it will take place.
In the meantime, the improvement of general technology continues, hour after hour, day after day.
Now ion drives are mature, but the thrust-to-weight ratio is still low. This is a technology primarily suited to multi-year unmanned missions.
Some of the most conventional ideas are still pretty far out of reach. XCOR’s world record rocketplane mail delivery last month is the latest stepping stone toward the point-to-point suborbital delivery market, but commercial viability is likely some years off. This market is explored by Ley including the 1931 experiment that “proved rocket ‘stamps’ found a market”. He concluded that:
It now seems doubtful whether there will ever be a long-range rocket mail, as hoped for in 1929…the rocket would need about 45 minutes for the trip. Counting an hour or so of delay—that is the time between shots—at the European end and 1½ to 2 hours for retrieving the rocket and bringing the mail ashore at the American end, the total transit time would be around four hours. The addressee would get his mail the same day; in contrast to ten days later via steamer. However, now that mail crosses the Atlantic in about 10 hours flight time, the gain is unimportant; especially since jet passenger liners will cut the flying time nearly in half. (p. 442)
| We will see if “amusement” has more staying power, innovation, and cash behind it than science, exploration and national pride. |
With unmanned landers, we can cut the retrieval time. For shots on demand, we can cut the delay time. Still, 45 minute mail is just not that much more interesting than overnight mail by jet liner—or perhaps supersonic business jet. Maybe we need Vinge’s flying FedEx boxes or vertical landing of the European mail delivery on a helipad in Manhattan. The fuel cost for a one-kilogram payload would be less than the cost of customer service for same day intercontinental deliveries, but there might not be sufficient demand for the infrastructure to be economically feasible. On the other hand, using it as a public relations move like Virgin is using its Virgin Galactic subsidiary to garner press and coolness for their overall corporate brand could be enough for one of the major package delivery companies to do it.
Worden’s idea of putting a soletta, or solar deflector, at Earth-Sun L-1 (in the path of sunlight to the Earth), so we can affect the weather goes all the way back to Oberth, albeit he wanted a sunrise or sunset polar orbit (See “Exploiting the Moon and saving the Earth”, The Space Review, November 7, 2005). Ley cites Oberth, 1923, “one could spread a large circular wire net simply by rotating it around its center. Small plane metal mirrors could be fitted into the space between the wires.” Mylar is the modern standard choice. Oberth anticipates using it to heat sea lanes, save crops from freezes, “or, if not needed, make the whole beam miss the earth.” (p. 367). We might get some mileage out of deflecting sunlight thereby cooling the Earth so we don’t have to cut back on carbon so much. Spot warming might well be worth more than general cooling—melting the artic ice cap might be worth more than the cost of the additional carbon abatement and the hardware to do spot warming might be much cheaper than deflection hardware.
On p. 478 we find the following: “Space travel presents legal problems along with the engineering problems, and while the legal problems are fewer in number they may be even more difficult to solve.” The FAA rules posted last week that establish the liability regime for space tourism are not the end of this road. Property rights for the Moon is still in the 1833 “tragedy of the commons” legal regime.
There are more gems in this book, such as the need for mobile missiles to fit on rail cars, piggyback staging instead of vertical staging, and many others. In addition to the musings about the future, there is a complete history of rocketry from black powder rockets to the V-2 and beyond. I highly recommend reading, or rereading, this classic. Having historical perspective can help reinvigorate exploration with the spirit of the pioneers. It can also provide a valuable grounding in reminding us that what was common knowledge then is uncommon knowledge now.
