I want to commend Dr. Rasool's statement to public attention. It corroborates and indeed expands on Professor Newell's admonition about flying supersonic transports in our delicate stratosphere before we know more than we presently do about the potential consequences.

Of critical importance is the length of time it will take to acquire the information we need. Dr. Rasool agrees with Professor Newell that 10 years appears to be a "realistic time scale" if research continues at its present rate.

However, Dr. Rasool believes the process can be speeded up to bring a definitive answer in 5 years.

Before we get on with the job of acquiring the necessary facts, we need to establish a far more comprehensive program of research than is presently available. We should concentrate on this rather than on building SST prototypes.

(The comments referred to on p. 453 follow :)

COMMENTS ON PROF. R. E. NEWELL'S TESTIMONY BY S. I. RASOOL

The testimony by Professor R. E. Newell on the decrease in ozone amount and increase in ultraviolet radiation resulting from SST operations is consistent with my knowledge of calculations on this subject. I would like to mention three points in connection with this testimony which seem to require further emphasis.

(1) An estimate of the ozone decrease produced by the injection of water vapor into the stratosphere requires a detailed study not only of the chemistry of water and ozone molecules, but also of the motions in the stratosphere. Water vapor when introduced in the upper atmosphere does not remain localized over one region, but will "diffuse" or spread both horizontally and vertically. Ozone does likewise. The question then is how fast and how far these constituents diffuse through the atmosphere, and what is the resultant concentration of ozone over various regions of the globe.

In particular, if the water vapor injected by SST's spreads uniformly over the globe, the average ozone decrease produced by SST's will be about 1 percent. The corresponding change in the 3000 A ultraviolet radiation will be increased in intensity by about 4 percent. However, if this water vapor remains concentrated near the airlanes, and is, for example, confined near these airlanes, then the ozone could be decreased in those regions of the globe by as much as 10 percent. The amount of 3000 Å ultraviolet radiation reaching the ground would then be increased by 30 percent, for the parts of the earth's surface under or near the airlanes.

A detailed calculation of diffusion in the stratosphere is needed to pin down the answer between these two extreme values. This is the most important point in my view.

So far no calculations on the effect of diffusion have been made. Consequently, at the present time there is a very large uncertainty in the magnitude of the ozone decreases caused by SST operations. The numbers quoted by Professor Newell, namely, a 4 percent decrease in ozone and consequently an 11 percent increase in the UV radiation at 3000 A at the surface of the earth, are based on assumptions regarding diffustion made by H. Harrison of Boeing Scientific Research Laboratories, which are reasonable but must be checked by exact calculations.

A project aimed at computing effects of diffusion accurately has been initiated at the Goddard Institute for Space Studies. It is hoped that within 6 to 9 months we will be able to narrow down the uncertainty in the ozone concentration by taking into account the vertical diffusion of water vapor in the stratosphere. (2) In addition to the effect of water vapor, it is also possible that other exhaust products from the SST can cause a significant decrease in ozone. These products include nitric oxide, nitrous oxide and hydrocarbons, as mentioned by Professor Newell. Calculations have not yet been made on their effect, because the basic chemical reactions are only beginning to be understood. This point requires emphasis because the additional effect of the above-mentioned constituents in the exhaust product could be as large as that of water vapor

alone. Studies on the decrease in ozone resulting from the nitrogen compounds in SST exhaust products are under way at the University of Colorado under the direction of Professor Julius London.

(3) The time period of at least ten years quoted by Dr. Newell to obtain "intelligent answers" to these problems appears to me to be a realistic time scale if research on the problem continues at its present rate. Global measurements of ozone and water vapor concentration over the whole stratosphere, and their variation with time for a period of at least one year and preferably two years or more, are needed, and will not be completed until 1975-1976 time frame, according to my knowledge of present plans. A number of additional years will be required to complete calculations based on the measurements, and then to interpret the results. If a decision is taken that the measurements are urgently required the process can be speeded up. It is my belief that then a definitive answer could be obtained in five years.

COMMITTEE RECESS

Tomorrow at 10 o'clock, we will continue hearings by witnesses in opposition to the SST and at 2 o'clock we are going to have a movie that will be exhibited by Astronaut Neil Armstrong and at 2:30 we will hear witnesses for the proponents of the SST.

We stand in recess until 10 a.m. tomorrow.

(Whereupon, at 7:15 p.m., Wednesday, March 10, the hearing was recessed to reconvene at 10 a.m., Thursday, March 11.)

57-918 0-71-12

CIVIL SUPERSONIC AIRCRAFT DEVELOPMENT (SST)

THURSDAY, MARCH 11, 1971

U.S. SENATE,

COMMITTEE ON APPROPRIATIONS,

Washington, D.C.

The committee met at 10:05 a.m., in room 1224, New Senate Office Building, Hon. Allen J. Ellender (chairman) presiding.

Present: Senators Ellender, Magnuson, Stennis, Bible, Proxmire, Inouye, Young, Smith, Allott, Case, and Percy.

OPPONENTS TO DEVELOPMENT

STATEMENT OF DR. GEORGE RATHJENS, MASSACHUSETTS
INSTITUTE OF TECHNOLOGY

SUBCOMMITTEE PROCEDURE

Chairman ELLENDER. The committee will please come to order. This morning, we shall continue to hear from the opponents of SST. The names of the witnesses have been furnished by Senator Proxmire, the first of whom this morning is Dr. George Rathjens. Chairman ELLENDER. All right, Doctor, you have a prepared statement?

Dr. RATHJENS. Yes, I do, Senator.

Chairman ELLENDER. You may proceed, sir.
Do you mind interruptions as you go along?
Dr. RATHJENS. No, I don't mind them at all.
Chairman ELLENDER Proceed.

PUBLIC POLICY

Dr. RATHJENS. Mr. Chairman, members of the committee, I am honored by this invitation to appear before you to comment on the question of whether or not the SST program should continue to be supported by the Federal Government as it has been for the last several years. I come with some hesitancy because I am not an expert on any particular part of this controversy. But I am here nevertheless because I feel it is an important public policy issue, some facets of which have not been as fully explored as I think they should be.

ECONOMIC RISKS AND ADVISABILITY OF GOVERNMENT INVESTMENT

I would like to withhold any comments on the environmental (and many other) aspects of the problem until the question period, focusing on at this time: (1) The question of the economic risks in going

ahead with the SST, and; (2) whether the venture makes sense as a Government investment in light of the risks involved.

Recent statements by Government spokesmen, particularly by Mr. Magruder before the House Subcommittee on Transportation on March 1, paint such a glowing picture of the SST that one wonders that private money sources are not falling all over themselves trying to finance the venture. Of course, they are not and the reason is that there is a very high probability that the optimistic projections of the FAA will not be realized. Indeed, a very recent Boeing advertisement characterizes it as a high-risk investment.

Any of a number of adverse developments could result in the program being a financial disaster. What I would like to do in the next few minutes is to discuss the sensitivity of the economic feasibility of the SST to a few of the critical factors about which there is uncertainty.

I would start by noting that the success of the SST is far more dependent on a favorable resolution of uncertainties than is generally the case with subsonic aircraft. This is a fundamental point which follows directly from the fact that the payload is small and the fuel requirements large compared to subsonic aircraft. Thus, the presently planned payload of the SST is only about 7 percent of the gross weight compared with about 14 percent for the 747 and the fuel consumed per seat-mile will be over twice as much.

This means that the economic feasibility of the SST will be much more sensitive to fuel costs, fuel consumption, and uncertainties in weight than for an aircraft like the 747. While FAA analyses are based on no increase in fuel costs, this seems like a dubious assumption considering the growth in energy demands and the difficulties in price negotiations with many of the petroleum producing countries.

Any increase in fuel costs will hurt the SST doubly: In an absolute sense in the effect of increased costs on air travel, and in a relative sense as compared with subsonic competition which will be less sensitive to fuel cost escalation. Far more serious would be changes in fuel consumption or structural weight.

A increase in fuel consumption of only 1 percent will apparently result in a reduction in SST payload of about 5 percent (2,500 pounds) and an increase in structural weight of 1 percent could result in an even greater payload degradation.

Let me now relate the question of sensitivity of performance to some of the very recent discussions of the noise problem.

In the last few days we have heard that with the use of noise suppressors and with appropriate engine modifications it will be possible to reduce noise during takeoff, and particularly sideline noise, to acceptable levels-presumably 108 pndb. This has been announced as if it were a breakthrough in dealing with the noise problem, but it is hardly that.

The real problem is not simply whether noise can be reduced to acceptable levels, but rather whether it can be done without a hopelessly adverse effect on the economics of the SST. It has been conceded that noise reduction will result in increased weight, increased drag, and reduced engine efficiency.

How serious this will be is not clear, and according to Boeing spokesmen, will not be clear until production specifications are developed