151 



diminishing in the future? Is there going to be more international 

 cooperation or less, or about the same? 



Dr. Friedman. I think there must be more international coopera- 

 tion. I mentioned one example, in interferometry. It is typical of 

 interferometry that you have the multiplicity of telescopes. That 

 makes it possible for various participants each to take the responsi- 

 bility for one of those elements, and then it is all put together as a 

 cooperative project. 



The Hubble Space Telescope now is a single telescope mission, 

 and it will produce images 10 times the detail we have ever had 

 before. But the prospects for the turn of the century by going into 

 interferometry are to improve that resolution a factor of another 

 thousand, and the challenge to astronomy is just extremely excit- 

 ing. 



I think all of the missions in that category do lend themselves to 

 international cooperation in a way in which the management is 

 not excessively complicated and in which the science ultimately is 

 done in a truly cooperative way with all of the benefits. 



Mr. FuQUA. You said you thought it would be good to do that. 



Dr. Friedman. Yes. 



Mr. FuQUA. Will that happen? 



Dr. Friedman. There are already serious discussions in interna- 

 tional forums of taking these next steps. There is a mission defined 

 internationally, ESA and the United States, for example, to 

 produce a mission called Quasat, which will put a large radio tele- 

 scope in orbit and use it in an interparametric mode with the 

 arrays of telescopes on the ground. 



Then one can foresee the next step where several of these tele- 

 scopes will be assembled on the space station and put into near- 

 Earth orbit and eventually very distant positions in space and carry 

 the resolution to its ultimate limit. There you can see responsibility 

 being divided in a very natural way amongst various nations that 

 really want to pursue those ultimate scientific goals. 



Mr. FuQUA. Mr. Brown. 



Mr. Brown. Dr. Friedman, continuing with astronomy for a 

 moment, and interferometry, the process can apply at any portion 

 of the spectrum, I presume; that is, you can improve the resolution 

 through interferometry processes in radio telescopes, optical tele- 

 scopes, and other telescopes as well? 



Dr. Friedman. Yes. 



Mr. Brown. Generally speaking, does that require multiple in- 

 struments? 



Dr. Friedman. Yes, it does. The essence of an interferometer is 

 that you have two or more telescopes which give you the separa- 

 tion that makes it comparable to the resolution of a dish of that 

 size, and the more telescopes you use to fill in the aperture, the 

 closer you come to getting a complete image in a short time. 



Mr. Brown. So that that would hold out the desirability of 

 having additional Hubble-type instruments in space as well as 

 radio astronomy instruments in space and other kinds of instru- 

 ments as well? 



Dr. Friedman. Yes. There are already well-advanced design ef- 

 forts to demonstrate that the next generation of telescopes, even in 

 the optical range that a Hubble telescope operates can be made 



