Beyond the Atmosphere: Early Years of Space Science

 
 
CHAPTER 10
 
LAUNCH VEHICLES
 
 
 
[134] It is not necessary for understanding the relationship of launch vehicles to the space science program to delve deeply into how they were developed, but a few principles should be understood. First, a number of different vehicles were required. One might have supposed that a single launch vehicle, which could do everything the program required, would be ideal. With only one manufacturing line, one kind of assembly, test, and launch facilities, one kind of operational equipment and procedures, and basically [135] one launch team, a substantial background of experience would quickly build up for that vehicle. Engineers and technicians would become thoroughly familiar with its characteristics and idiosyncrasies, so that a high degree of reliability could be ensured.
 
But in an era when a launch vehicle was expended for each firing, the economics would not be favorable. For, to be acceptable, a single vehicle would have to be able to accomplish both the simplest and the most difficult of the missions required-from small, near-earth satellite missions to manned flights to the moon. On the most difficult missions, the launch vehicle would presumably operate most efficiently, and the costs would be commensurate with the accomplishments. But to use such a vehicle for less demanding missions would be most inefficient; indeed, the cost of the launch vehicle could overwhelm the cost of the spacecraft. To mitigate this problem of cost there would, of course, be pressure to fly many small missions on a single launch vehicle, or to let small missions ride piggyback on larger ones, thus, reducing the cost per spacecraft; but then different kinds of complications would enter in. Some of these would be fundamental, as when one set of experiments required a circular orbit, another set an eccentric orbit, still another a polar orbit, and a fourth an equatorial orbit.
 
For expendable launch vehicles such considerations led to the conclusion that the most efficient approach would be a graduated series running from a small, inexpensive vehicle to the very large, very expensive ones. The gradation between vehicles would be large enough to yield a substantial increase in payload and mission capability, but small enough to avoid having to use vehicles too costly for their assigned missions. Obviously the way in which these requirements were met was a matter of judgment, and in some respects arbitrary. The subject was constantly under study by both the military and NASA.8
 
Second, the basic physics of rockets dictated that major launch vehicles should be multistage, or step, rockets-that is, combinations of two or more rockets, called stages, which burn one after the other. As soon as the first stage has used its propellants, it is discarded, after which at an appropriate time the second stage is ignited. When the second stage has burned out and been discarded, the third stage is ready to fire. And so on. Multistaging is important for rockets that must work against the force of gravity, for otherwise the propellants must supply the energy needed to propel the entire rocket structure against the pull of gravity for the whole launching phase. But with staging, in which portions of the structure are discarded as soon as they are no longer needed, only a small fraction of the entire vehicle need be propelled into the final orbit or space trajectory. The early rocket pioneers recognized the importance of staging, a point that Robert Goddard elaborated in his famous Smithsonian paper.9 In the space program two-stage and three-stage vehicles became common, four-and five-stage combinations not uncommon.
 
[136] In the scramble to put together a national launch vehicle capability after the formation of NASA, it was natural that whatever vehicles were available or could be assembled from the existing military programs would be used. In 1959 six out of the seven vehicles that were available to NASA came largely from the missile program.10 The seventh was Vanguard, which had been built by the Navy for the IGY.
 
To expand the national capability, additional vehicles would be developed (fig. 10). Scout, a four-stage, solid-propellant vehicle, would provide an inexpensive means for launching 70 kilograms to 185 (or even 550) kilometers. Vega and Centaur, the latter using the high-energy propellants liquid hydrogen and liquid oxygen, would substantially extend the launch capability of Atlas-based vehicles. Juno V vehicles and Nova were intended to support a variety of manned missions. Nova was expected to generate a thrust of 6000000 pounds-almost 27,000,000 newtons-and would be required for launching men in a direct ascent from the ground to the moon's- surface.
 
Fifteen years later the situation was entirely different. By then a bewildering variety of rocket stages and launch vehicle combinations had been developed, along with an extensive literature.11 What the vehicles could do for the various Space missions can be deduced from the performance figures for the launch vehicles in figures 10 through 14.
 
As seen in figure 11, by 1962 the Hustler and Vega had been eliminated. Likewise, Juno II, which had not proved particularly useful, had beer dropped. Nova plans called for doubled thrust, and Saturn was to rely on liquid-hydrogen, liquid-oxygen engines for its upper stages. By 1966 Now had disappeared because of NASA's decision in July 1962 to use lunar-orbit rendezvous instead of direct ascent for the Apollo missions.12 Several versions of Saturn would support NASA's manned spaceflight programs; the largest, Saturn V, would be used for the manned lunar missions.13 The Department of Defense preferred not to be tied into the expensive and highly experimental Saturn, so in following years the Titan III line of launchers was introduced into the stable to support large-scale military missions. Titan III additions can be seen in the display for 1972 (fig. 13), at which time the only Thor-based vehicle remaining was Delta.
 
These launch vehicles, with the sounding rockets discussed at the start of this chapter, made up the backbone of U.S. capability to explore and investigate space. They resulted from joint planning by NASA and the military to serve their respective needs.14 Other rockets and rocket stages were put together for special purposes, usually by the military, but their existence did not change the overall picture.
 
In the 1970s a basic change was initiated with the commitment to the Space Shuttle, which in the 1980s would supplant most of the expendable boosters for launching spacecraft into near-earth orbit. The launch vehicle line-up in the fall of 1976 (fig. 14) shows how the elimination of the [137] Saturns, following the completion of the Apollo and Skylab programs by the mid-1970s, and the prospect of the Space Shuttle by the 1980s had thinned out the stable. Only five vehicles remained: Scout for small payloads, Delta and Atlas-Centaur for medium and large payloads, and two Titan III combinations for the very large payloads.
 
Throughout the entire evolution of the launch vehicle stable, both Scout and Delta remained. Relatively inexpensive, able to support a substantial number of the researches that scientists wanted to do, these launch vehicles had great appeal. Even with the Shuttle in operation, Scout at least was likely to remain, for even the Shuttle might not prove economical for small missions with a wide variety of special trajectory requirements.
 
Scout and Delta also illustrate another feature of the national launch vehicle program. As the group of vehicles improved as a family over the years, performance of the individual vehicles also improved. In 1962 Scout could put 100 kg into a near-earth orbit; by the 1970s this performance had doubled. In the same period Delta's performance had shown an even greater growth. In 1962 Delta could send several hundred kilograms into a near-earth orbit or 25 kg to Mars or Venus; by 1976 Delta could loft 2000 kg into a 185-km orbit or 340 kg to the near planets. The increased performance, which most vehicles experienced over the years, was brought by continuing programs of improving and uprating the vehicles. While improvement programs were the pride of the vehicle engineers, they were sometimes the bane of top management, which would often have preferred to settle upon some acceptable level of performance and then stop spending any more money on vehicle development.
 
Like the United States, the Soviet Union developed a launch vehicle stable.15 During the 1960s, however, the Soviet Union appeared to rely on fewer kinds of vehicles than did the United States, preferring to use a single model for a wider variety of missions. The Russian preference may be prima facie evidence that the economic factors of using large vehicles for small-payload missions were not as prohibitive as American planners felt they were; but comparing Russian economics with American is a risky business. The USSR may simply have decided to pay the extra cost for the convenience afforded.
 
Only the United States and the Soviet Union developed extensive launch capabilities. Other nations interested in space research and applications turned largely to the United States for assistance in launching spacecraft or individual experiments, as will be explored in chapter 18. Some nations, however, desiring to lessen this dependence, proceeded to develop vehicles of their own. Among those were Britain, France, Japan, People's Republic of China, and the European Launcher Development Organization, a coalition of countries that pooled resources to develop a launcher approaching the Atlas-Agena capability.16 Italy set up an equatorial launching facility in the Indian Ocean off the coast of Kenya, but used the American Scout as launch vehicle.17
 

[
pp138-139Figure 10. 1959.
Figure 11. 1962.
Figure 12. 1966.
Figure 13. 1972.
Figure 14. 1976.
 
[140] By 1966-when Centaur became fully operational-the United States could at last launch spacecraft for just about any space mission the country might want to undertake, except the very demanding ones requiring the Saturn or Titan still under development. Although the debate over whether the United States could or could not match Russian launch capability still arose occasionally, the subject no longer had the importance it once did. As long as the United States could carry out the scientific investigations and make the space applications it desired-sometimes using miniaturization techniques to overcome limitations on total payload weights-the country could compete with the Soviet Union on essentially equal terms, and the comparative sizes of rockets were then an artificial criterion on which to judge Soviet and U.S. space prowess.
 
The ability to launch objects and men into space rested on a substantial investment in manpower and facilities-design, engineering, construction, assembly, and test facilities in both industry and government. Most visible were the launching ranges, which along with the launch vehicles themselves symbolized. the nation's space capability. In the United States the principal facilities were the Eastern Test Range, with launch areas at Cape Canaveral and Merritt Island in Florida; and the Western Test Range, for which the launching areas were at Vandenberg Air Force Base in California.18 A smaller launch station was used by NASA for firing Scouts from Wallops Island on the Virginia coast.19 Supplementing these were sounding rocket ranges at the White Sands Missile Test Facility in New Mexico, Wallops Island, Point Mugu in California, and Fort Churchill in northern Canada. Occasionally shipborne launchers were used for special missions.
 
The Soviet Union operated a number of major launch ranges out of Tyuratam, Kapustin Yar, and Plesetzk.20 A few other countries established satellite launch ranges.21 By invitation American sounding rockets were fired at numerous ranges around the world-for example, at Thumba in India, at Woomera in Australia, and at Andoeya, Norway.22
 

 
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