Mathematica and the TAOS Concept

In late October, there was an unexpected external intervention in the shuttle decision process. Mathematica, the Princeton-based company that NASA had selected to carry out an independent analysis of the cost-effectiveness of a space shuttle, had submitted its final report with respect to the two-stage fully reusable shuttle concept in summer 1971. But this submittal came after

NASA had already decided to abandon the fully reusable approach and to examine alternative shuttle designs. The Mathematica report had made the point that while the two-stage fully reusable design was marginally cost- effective, it was not necessarily the optimum shuttle design from an eco­nomic perspective. NASA had decided to extend Mathematical work to examine the economic dimensions of the alternate shuttle concepts during the extended study period.

The person in day-to-day charge of the Mathematica effort was economist Klaus Heiss. During September, Heiss visited with two of the study contrac­tors, McDonnell Douglas and Grumman, to get information on the alterna­tives being examined by the two companies. Each firm had been allowed by NASA to allocate 10 percent of its study effort to a shuttle concept in which an orbiter with an external propellant tank was carried to orbit by the power of its own engines combined for the initial few minutes of the flight with the much higher thrust of one or two conventional rockets attached to the orbiter or its propellant tank, all engines firing from the launch pad on. McDonnell Douglas had labeled its concept rocket-assisted takeoff (RATO); Grumman, thrust-assisted hydrogen-oxygen (TAHO) takeoff. Heiss got cost and other data on those configurations and other designs under study from the two companies and also from a third study contractor, Lockheed. He used that information as input to the complex computer-based model that Mathematica had developed for its shuttle-related work. (Heiss did not interact with the fourth shuttle study contractor, North American Rockwell, because he “was convinced from the beginning that they would win the competition.” Apparently, he was aware of the bias toward awarding the shuttle contract to a California firm.) Heiss discovered that “whatever space program [mission model] you used and even if you changed interest rates from five percent to ten percent to fifteen percent, again and again and again the same configura­tion came out” as economically preferred—the RATO/TAHO approach. He labeled this concept TAOS (thrust-assisted orbiter shuttle).16

Heiss faced a dilemma with respect to what to do with that finding. The second Mathematica report was not due until the end of January 1972, and by that time a decision on the space shuttle design might have been reached. He was aware of the conflicts between OMB and NASA over shuttle approval, and thought that his findings could help resolve the debate. Heiss told Bob Lindley that “I’m going to do something that maybe I’m not supposed to, but since it’s so clear. . . I’m going to write up my conclusions in fifteen or twenty pages and send that to [NASA Administrator] Fletcher.” Heiss chose not to route his analysis through Dale Myers, believing that Myers and his team were still trying to find a way to get approval for some version of a two-stage shuttle in order to have enough work to occupy both Houston and Huntsville.17

The Heiss memorandum, dated October 28, 1971, was titled “Factors for a Decision on a New Reusable Space Transportation System.” It was co­signed by Oskar Morgenstern, Mathematica’s head. The memo led off with three conclusions, all emphatically stated in capital letters:

1. A REUSABLE SPACE TRANSPORTATION SYSTEM IS ECONOMICALLY FEASIBLE, ASSUMING THAT THE LEVEL OF UNMANNED U. S. SPACE ACTIVITY WILL NOT BE LESS THAN IT HAS BEEN ON THE AVERAGE OVER THE LAST EIGHT YEARS.

2. AMONG THE MANY SPACE SHUTTLE CONFIGURATIONS SO FAR INVESTIGATED, AND WHICH ARE DEEMED TO BE TECHNOLOGICALLY FEASIBLE, A THRUST ASSISTED ORBITER SHUTTLE (TAOS) WITH EXTERNAL HYDROGEN/OXYGEN TANKS EMERGES AT PRESENT AS THE ECONOMICALLY PREFERRED CHOICE.

3. THE DEMAND FOR SPACE TRANSPORTATION IN THE 1980’S BY THE NATIONAL AERONAUTICS AND SPACE ADMINISTRATION, THE DEPARTMENT OF DEFENSE, BUT PARTICULARLY BY COMMERCIAL AND OTHER USERS IS THE BASIS FOR THE ECONOMIC JUSTIFICATION FOR THE TAOS PROGRAM.

The memorandum noted that “in part the choice of the current Mark I-Mark II approach was forced by a peak funding requirement for space shuttle development of, say, $1 billion per year. In this approach, however, several important parts of the system would be postponed in some configurations while other configurations with the same total funding requirement assure an early IOC [initial operating capability] date not only of the space shuttle alone, but also of the space tug" It suggested that “the non-recurring costs of TAOS are estimated by industry to be $6 billion or less” and noted that the TAOS configuration would promise “the same capabilities as the original two-stage shuttle.” Heiss added that “the most economic TAOS would use the advanced orbiter engines immediately” and that “the cost per launch of TAOS can be as low as $6 million or less.” The memo thus concluded that “TAOS practically assures NASA of a reusable space transportation system with major objectives achieved"1

It is difficult to judge the impact of the Heiss memorandum on the ulti­mate decision regarding the shuttle program. A version of the TAOS con­cept was indeed the shuttle configuration selected for development. Heiss suggests that “as soon as Fletcher read” his memo, he concluded “that’s the solution to this problem” and “ran all over town with it,” going first to OMB and saying “this group of outside people finds that this makes sense, so why do you fool around with this negative attitude?” Fletcher himself suggested that the Mathematica work reflected in the memo “did influence the decision in the sense that if it had come out negative, we’d have been in trouble.” But, he added, “the Mathematica stuff all along was really supportive of our decision, not determinative.”19 The memorandum did not make its way to those managing the shuttle studies at the Manned Spacecraft Center, who were interacting directly with their study contrac­tors in evaluating the final shuttle configuration. The TAOS concept they ultimately adopted likely reached them through those interactions, not as a result of the Heiss intervention. As the shuttle debate continued in the last two months of 1971, there were few, if any, references in the interactions between NASA, OMB, OST, and the White House to this memorandum or to the economic analyses it reported. It seems as if the Mathematica memo was one, but only one, of the influences that converged on the concept of a “thrust assisted” shuttle orbiter as the best technical choice for a new space transportation capability.