Wernher von Braun to the Vice President of the United States, 29 Aprll 1961

April 29, 1961

The Vice President of the United States
The White House
Washington 25, D.C.

My dear Mr. Vice President:

This is an attempt to answer some of the questions about our National Space Program raised by The President in his memorandum to you dated April 20, 1961. I should like to emphasize that the following comments were strictly my own and do not necessarily reflect the official position of the National Aeronautics and Space Administration in which I have the honor to serve.

Question 1. Do we have a chance of beating the Soviets by putting a laboratory in space, or by a trip around the moon, or by a rocket to land on the moon, or by a rocket to go to the moon and back with a man? Is there another space program which promises dramatic results in which we could win?

Answer: With their recent Venus shot, the Soviets demonstrated that they have a rocket at their disposal which can place 14,000 pounds of payload in orbit. When one considers that our own one-man Mercury space capsule weighs only 3,900 pounds, it becomes readily apparent that the Soviet carrier rocket should be capable of

• launching several astronauts into orbit simultaneously. (Such an enlarged multi-man capsule could be considered and could serve as a small “laboratory in space”. )
• soft-landing a substantial payload on the moon. My estimate of the maximum soft-landed net payload weight of the Soviet rocket is capable of is about 1,400 lb (one-tenth of its low orbit payload). This weight capability is not sufficient to include a rocket for the return flight to earth of a man landed on the moon. But it is entirely adequate for a powerful radio transmitter which would relay lunar data back to earth and which would be abandoned on the lunar surface after completion of this mission. A similar mission is planned for our own “Ranger” project, which uses an Atlas-Agena B boost rocket. The “semi-hard” landed portion of the Ranger package weighs 293 pounds. Launching a scheduled for January 1962.

The existing Soviet rocket could furthermore hurl a 4,000 to 5,000 pound capsule around the Moon with ensuring re-entry into the earth’s atmosphere. This weight allowance must be considered marginal for a one-man round-the-moon voyage. Specifically, it would not suffice to provide the capsule and its occupant with a “safe abort and return” capability, — a feature which under NASA ground rules for pilot safety is considered mandatory for all manned space flight missions. One should not overlook the possibility, however, that the Soviets may substantially facilitate their task by simply waving this requirement.

A rocket about ten times as powerful as the Soviet Venus launch rocket is required to land a man on the moon and bring him back to earth. Development of such a super rocket can be circumvented by orbital rendezvous and refueling of smaller rockets, but the development of this technique by the Soviets would not be hidden from our eyes and would undoubtedly require several years (possibly as long or even longer than the development of the large direct-flight super rocket).

Summing up, it is my belief that

1. we do not have a good chance of beating the Soviets to a manned "laboratory in space." The Russians could place it in orbit this year while we could only establish a (somewhat heavier) laboratory only after the availability of the reliable Saturn C-1 which is in 1964.
2. we have a sporting chance of beating the Soviets to a soft-landing of a radio transmitter station on the moon. It is hard to say whether this objective is on their program, but as far as the launch rocket is concerned, they could do this at any time. We plan to do it with the Atlas-Agena B-boosted Ranger #3 in early 1962.
3. we have a sporting chance of sending a three-man crew around the moon ahead of the Soviets (1965/66). However, the Soviets could conduct a round-the-moon voyage earlier if they are ready to wave certain emergency safety features and limit the voyage to one man. My estimate is that they can only perform this simplified task in 1962 or 1963.
4. we have an excellent chance of beating the Soviets to the first landing of a crew on the moon (including return capability, of course). The reason is that the performance jump by a factor of 10 over their present rockets is necessary to accomplish this feat. While today we do not have such a rocket, it is unlikely that the Soviets have it. Therefore, we would not have to enter the race toward this obvious new goal in space exploration against hopeless odds favoring the Soviets. With an all-out crash program I think we could accomplish this objective in 1967/68.

Question 2. How much additional cost?

Answer: I think I should not attempt to answer this question before the exact objective and the time plan for the accelerated United States space program have been determined. However, I can say with some degree of certainty that the necessary funding increasing me the objectives d) above would be well over $1 billion for FY 62, and that the required increase for subsequent fiscal years may run twice as high or more.

Question 3. Are we working 24 hours a day on existing programs question if not, why not? if not, will you make recommendations to me as how work can be sped up.

Answer: We are not working 24 hours a day on existing programs. At present, work on NASA’s Saturn project proceeds on a basic one-shift basis, with overtime and multiple shift operations approved in critical “bottleneck” areas.

During the month of January, February and March 1961, NASA’s George C. Marshall Space Flight Center, which has systems management for the entire Saturn vehicle and develops the large first stage as an in-house project, has worked an average of 46 hours a week. This includes all administrative and clerical activities. In the area critical for the Saturn project: (design activities, assembly, inspecting, testing), average working time for the same period was 47.7 hours a week with individual peaks up to 54 hours per week.

Experience indicates that in Research & Development work longer hours are not conducted to progress because of the hazards introduced by fatigue. In the aforementioned critical areas, a second shift would greatly alleviate the tight scheduling situation. However, additional funds and personal spaces are required to hire a second shift, and neither are available at this time. In this area, help would be most effective.

Introduction of a third shift cannot be recommended for Research & Development work. industry-wide experience indicates that a two-shift operation with moderate but not excessive overtime reduces the best results.

In industrial plants engaged in the Saturn program the situation is approximately the same. Moderately increase funding to prevent greater use of Premium paid overtime, prudently applied to real “bottleneck” areas, can definitely speed up the program.

Question 4. In building large boosters we should put our emphasis on nuclear, chemical or liquid fuel, or a combination of these three?

Answer: It is the consensus of opinion among most rocket men and reactor experts that the future of the nuclear rocket lies in deep space operations (upper stage of chemically-boosted rockets or nuclear space vehicles departing from an orbit around the earth) rather than launching (under nuclear power) from the ground. In addition, there can be little doubt that the basic technology of nuclear rockets is still in its early infancy. The nuclear rocket should therefore be looked upon as a promising means to extend and expand the scope of our space operations in the years Beyond 1967 or 1968. It should not be considered as a serious contender in the big booster problem of 1961.

The foregoing comment refers to the simplest and most straightforward type of nuclear rocket, viz. the “heat transfer” or “blow down” type, whereby liquid hydrogen is evaporated and superheated in a very hot nuclear reactor and subsequently expanded through a nozzle.

There is also a fundamentally different type of nuclear rocket propulsion system in the works which is usually referred to as “ion rocket” or “ion propulsion”. Here, the nuclear energy is first converted into electrical power which is then used to expel “ionized” (i.e., electrically charged) particles into the vacuum of outer space and extremely high speeds. The resulting reaction force is the ion rockets “thrust”. It is in the very nature of nuclear ion propulsion systems that they cannot be used in the atmosphere. While very effective in the propellant economy, they are capable of only very small thrust forces. Therefore they do not qualify as “boosters” at all. The future of nuclear ion propulsion lies in its application for low-thrust, high-economy cruise power for interplanetary voyages.

As to “chemical or liquid fuel” The President’s question undoubtedly refers to the combination between “solid” and “liquid” in quote rocket fuels, both of which involve chemical reactions.

At the present time, are most powerful rocket boosters (Atlas, the first stage of Titan, the first stage of Saturn) are all still liquid fuel rockets and all available evidence that the Soviets are also using liquid fuels for their ICBMs and space launchings. The largest solid fuel rockets in existence today (Nike Zeus booster, first stage Minuteman, first stage Polaris) are all substantially smaller and less powerful. There is no question in my mind, when it comes to building very powerful booster rocket systems, the body of experience available today with liquid fuel systems greatly exceeds that with solid fuel rockets.

There can be no question that larger and more powerful solid fuel rockets can be built and I do not believe that major breakthroughs are required to do so. On the other hand it should not be overlooked that a casing filled with solid propellant and the nozzle attached to it, while entirely capable of producing thrust, is not yet a rocket ship. And although the reliability record of solid fuel rocket propulsion units, thanks to their simplicity, is impressive and better than that of liquid propulsion units, this is not apply to complete rocket systems, including guidance systems, control elements, stage separation, etc.

Another important point is that booster performance should not be measured in terms of thrust force alone, but in terms of total impulse; i.e., the product of thrust force and operating time. For a number of reasons it is advantageous not to extend the burn time of solid fuel rockets beyond about 60 seconds, whereas most liquid fuel boosters have burning times of 120 seconds and more. Thus, a 3-million pound thrust solid rocket of 60 second burning time is actually not more powerful than the 1 1/2 million pound thrust liquid booster of 120 second burn time.

My recommendation is to substantially increase the level of effort in funding the field of solid fuel rockets (by 30 or 50 million for FY 62) with the immediate objectives of

• demonstration of the feasibility of very large segmented solid fuel rockets. (Handling and shipping of multi-million pound solid fuel rockets becoming unmanageable unless the rocket consists of smaller individual segments which can be assembled in building block Fashions at the launching site.)
• development of simple inspection methods to make certain that such huge solid fuel rockets are free of dangerous cracks or voids
• determination of the most suitable operational methods to ship, handle, assemble, check and launch very large solid fuel rockets. This would involve a series of paper studies to answer questions such as
  1. Are clusters smaller solid rockets, or huge, single-poured-in-launch-site solid fuel rockets, possibly superior to segmented rockets? This question must be analyzed not just from the propulsion angle, but from the operational point of view for the total space transportation system and its attendant ground support equipment.
  2. Launch pad safety and range safety criteria (How is the total operation at Cape Canaveral affected by the presence of loaded multi-million pound solid fuel boosters?)
  3. Land versus off-shore versus sea launchings of large solid fuel rockets.
  4. Requirements for man landings (How to shut the booster off in case of trouble to permit safe mission abort and crew capsule recovery? If this is difficult, what other safety procedures should be provided?)

Question 5. Are we making maximum effort? Are we achieving necessary results?

Answer: No, I do not think we're making maximum effort

In my opinion, the most effective steps to improve our national stature in the space field, and see things up would be to

• identify a few (the fewer the better) goals in our space program as a objectives of highest national priority. (For example, let’s land a man on the moon in 1967 or 1968.)
• identify those elements of our present space program that will qualify as immediate contributions to the objective. (For example, soft landings of suitable instrumentation on the moon to determine the environmental conditions man would find there.)
• put all the elements of our national space program on the “back burner”.
• add another more powerful liquid fuel booster to our national launch vehicle program. The design parameters of this booster should allow a certain flexibility with a desired program reorientation as more experience is gathered.

  Example: Develop in addition to what is being done today, a first-stage liquid-fuel booster of twice the total impulse of the Saturn’s first stage, designed to be used in clusters if needed. With this booster we could

  1. double the Saturn’s presently envisioned payload. This additional payload capacity would be very helpful for soft instrumentation landings on the moon for circumlunar flights and for the final objective of a manned landing on the moon (if a few years from now the route via orbital re-fueling should turn out to be a more promising one.)
  2. assemble a much larger unit by strapping three or four boosters together into a cluster. This approach would be taken should, a few years hence, orbital rendezvoud and refueling run into difficulties and the “direct route” for a manned lunar landing thus appears more promising.

Summing up, I would like to say that in the space race we are competing with a determined opponent whose peacetime economy is on a wartime footing most of our procedures are designed for orderly peacetime conditions I do not believe that we can win this race unless we take some measures which thus far if they considered acceptable only in times of national emergency

Yours respectively,

Wernher von Braun