launch in 1972; to preserve the prototype payload package for possible future use; and to accomplish where possible the OAO-B objectives with OAO-C as the, fourth and last OAO mission. We also instructed GSFC to continue the design effort on the Small Astronomy Satellite (SAS-D), a small spacecraft designed to operate in the ultraviolet portion of the spectrum. In addition, we are planning to increase our effort on the feasibility studies and technological development of the Large Space Telescope (LST). We are also considering a 12- to 2meter telescope as a possible intermediate step in a logical program leading up to the final LST.

High Energy Astronomy Observatory (HEAO).-The next topic that I want to discuss is the High Energy Astronomy Observatory (HEAO). HEAO is the major new start that we are proposing in the astronomy program.

Chart SG70-276 shows a concept of HEAO. It will be about 30-feet long, 8.3 feet in diameter and weigh about 10 tons. Of the 10 tons some 5 to 7 tons will be experimental hardware. It will be placed into a 200nautical mile circular orbit by a Titan launch vehicle. In our fiscal year 1972 budget we are asking for authorization to design, develop, build, and launch two of these spacecraft in 1975 and 1976, and to begin preliminary design studies on two more. Based on the preliminary work we have done to date, we estimate that the total cost for two of these spacecraft, that is, the first two, including the preparation of the experimental hardware, will be between $180 million and $250 million. The two launch vehicles will cost an additional $27.2 million.

Why do we think HEAO is so important? What are the views of the scientific community regarding the project? Do we see any practical value from the knowledge that we will gain from it? Let me discuss the rationale for HEAO.

Modern civilization differs from the earlier history of mankind by its ability to unlock and use energy that has been stored by nature for millions or even billions of years. The first step was the use of chemical processes to release energy stored in fossil fuels and use that energy for driving machines, for generating electricity and for making explosives. Within a few decades after discovering that nuclear energy powers the stars, we discovered ways to tap the energy stored in the nuclei of atoms and to use that energy to generate electricity here on earth.

Astronomers have now discovered astronomical objects quasars and pulsars-that radiate amounts of energy that vastly surpass the nuclear processes we know and understand. Unlike classical stars, however, these objects do not radiate most of their energy in visible light but rather as X-rays, or, in some cases, as infrared or as radio waves. New astronomical tools such as the HEAO are required to understand these objects.

Evidence is accumulating to indicate that some "stars" are composed of closely packed matter in the form of neutrons with densities as high as 1 million billion times that of water. This density approaches and perhaps exceeds the density of the fundamental particles themselves. The study of these so-called neutron stars should lead to a better understanding of the new fundamental physical processes involved. This knowledge in turn will provide insight into an important questionhow was the universe created? All at once, in a "big bang"? Or is continuous generation taking place? Or was the universe created by some as yet unforeseen process?

An important aspect of space research is the potential for surprising discoveries. The HEAO has a rich potential for such discoveries because it will investigate a new realm of physics the applicability of natural laws under the extremes of gravitational force, density, temperature, and magnetic fields. These experimental conditions cannot be produced on earth or in any place in the solar system but such conditions can be studied by observing certain objects in our own galaxy or in other parts of the universe.

These are some of the reasons for starting HEAO. To give you some feeling for the view of the scientific community about the value of the types of studies we will be able to do with HEAO, let me quote from Freeman Dyson on the "Future of Physics" in the September 1970 issue of Physics Today. There Dr. Dyson states, and I quote:

I find that the most exciting part of physics at the present moment lies on the astronomy frontier and I think there is a better-than-ever chance that the major discoveries in the next 30 years in high energy physics will be made with cosmic rays."

Many scientists share Dr. Dyson's opinion. As early as 1967 the President's Scientific Advisory Committee (PSAC) recommended greater emphasis on X-ray astronomy. We asked the Astronomy Missions Board (AMB) to consider carefully the strategy for astronomy for the decade of the 1970's. After such consideration and much debate betweeen solar astronomers, optical astronomers, astrophysicists and nuclear physicists, that group came to the conclusion that HEAO

should have the highest priority for a major new start in the astronomy program. The National Academy of Sciences (NAS) summer study in 1970 rated HEAO as the highest priority program in space astronomy and the general consensus among the scientists from all the disciplines in that study was that HEAO had the highest scientific priority of all the projects considered.

Why do we want to start HEAO at this time? Are we ready? What preparations have we made to proceed?

We have been preparing carefully for HEAO for the past 5 to 6 years. This preparation has taken the form of feasibility studies at the Marshall Space Flight Center (MSFC) ot analyze the experiments that we want to perform in order to determine what kind of a spacecraft would be required-how large it would be, what pointing capability it should have, and what power and telemetry would be required. This preparation has also taken the form of balloon flights to check out the performance of the scientific instruments and to get preliminary measurements on the flux of gamma rays and high energy cosmic rays. Chart SG71-2690 is a picture of a 4-ton payload which Dr. Luis Alvarez developed to measure high energy cosmic rays, a good example of the large size of experiments in the balloon program. From this chart you can get a good feeling for the size of that particular payload, and if you consider that it is launched on a 10- to 20million cubic foot plastic balloon not much thicker than Saran Wrap, you can see that this type of activity has its own unique problems.

We used sounding rockets to gain some idea of the intensity of radiation from X-ray sources and we recently flew the small astronomy satellite (SAS-A) to enable us to systematically map the sky

in the X-ray portion of the spectrum. We have done a substantial amount of laboratory work developing instruments and checking them out. Finally, underlying all of this has been a vast amount of theoretical and analytical work carried out to provide the insight needed to ask the best questions of nature as we attempt to understand the processes that I just discussed.

We also made financial preparations for starting HEAO at this time. As a part of the preparation of the fiscal year 1971 budget, that is, last year's budget, we carefully considered the question as to whether we should continue the orbiting astronomical observatories with an OAO-D spacecraft. In view of the interest in, and high priority assigned to, HEAO we deliberately planned at that time to phase out the OAO program after OAO-C in order to help provide the resources for the development of HEAO. Similarly, after the failure of OAO-B, we considered the question of a replacement and again decided in favor of HEAO.

We recognize that HEAO is a substantial project; however, we feel that the rationale behind it is sound. From the potential results to be obtained and because of its scientific interest, we believe it is in the national interest to proceed with it at this time.

I would like to close the discussion of HEAO with a brief discussion of the present status. We have defined in detail the first two HEAO missions. The scientific experiments have been selected for these two missions. The Marshall Space Flight Center (MSFC) has been assigned the responsibility for the development of HEAO. Two contractors, TRW, Inc. and the Grumman Aerospace Corp., working under the direction of MSFC, will shortly complete the phase B studies of the project.

I might say, Mr. Chairman, for those members of the committee who may be interested, we have models of the HEAO, one prepared by TRW and one prepared by the Grumman Aerospace Corp., in the back of the room if, after the hearing, they want to examine them.

We plan to issue a request to industry for proposals early in the fiscal year 1972 and to choose a spacecraft contractor in late 1971 or early 1972. We have started the preliminary design of HEAO-C and D missions and the major experimenters for HEAO-C have been selected and are participating in the design of that mission.

In summary, HEAO is an excellent scientific project with a high potential for discovery and for producing information of value.

HEAO has been reviewed by several astronomy groups and by the interdisciplinary priorities study at Woods Hole in 1970. Each of these groups has endorsed HEAO as an outstanding project and given it top priority.

HEAO, both the spacecraft and experiments, have been studied and developed over the past several years so that technically we are ready to proceed.

HEAO is an integral part of this Nation's astronomy program for the 1970's.

Mr. Chairman, perhaps I should stop at this point in time in case there are specific questions with regard to HEAO.

Mr. KARTH. Thank you very much, Dr. Naugle.
Mr. Chairman.

59-311 0-71-No. 2, pt. 3- -12

Chairman MILLER. I have no questions. I want to congratulate you on a very fine statement.

Mr. KARTH. Mr. Mosher.

Mr. MOSHER. You say on page 13 that the scientific experiments have been selected for these two missions, but this is all new to me. Can you tell me more specifically what these experiments will be? How many are there?

Dr. NAUGLE. Well, Mr. Mosher, there are three types of experiments that we have selected for the first two missions of HEAO. There are what we call X-ray experiments to study the flux and the location of sources of X-rays. That is, of stars and other objects that emit X-rays. There are experiments to study what we call gamma rays. These are another form of electromagnetic radiation that is produced in nuclear processes.

Finally, there are experiments to study high energy cosmic rays. High energy cosmic rays are particles rather than electromagnetic radiation. They are composed of neutrons, protons, helium, carbon, nitrogen, oxygen, and so on up the scale to perhaps nuclei even heavier than uranium nuclei.

Twelve experiments have been selected for HEAO-A and B. I would be glad to submit for the record the titles of the experiments, the principal investigators and the institutions that have been selected, or I can give them right now if you want me to.

Mr. MOSHER. This should be in the record, I think. (The material requested follows:)