Since we didn’t get a “no” answer to our question, we have been encouraged to do more experiments with other subjects and other types of conversations. We also have begun to look for more than a yes-or-no answer; we now want to find out how serious various amounts of pure delay would be. Some of my colleagues have been working on this problem by furnishing special four-wire telephones to a group of people, so that echo-free delay can be inserted in the line when one member of this test group calls another member. Their experiment has confirmed our finding that conversation with a round-trip pure delay of 1.2 seconds is not impossible, but it has also shown that the degradation of conversation that results is not trivial. Recently an international committee on commercial telephone standards set the maximum permissible echo-free delay (round-trip) at 0.7 seconds. However, the search for a more precise evaluation is still going on. Peter D. Bricker _was born in Scranton, Pennsylvania, and received an A.B. from Bucknell University in 1950 and an M.A. in 1952 and a Ph.D. in 1954 from the Johns Hopkins University. He joined Bell Telephone Laboratories in 1954, and has been engaged in psychological studies of telephone color preferences, pushbutton set designs, voice identification, and transmission quality evaluation._ CASE HISTORY NO. 6 How Can We Repair an Orbiting Satellite? E. Jared Reid _Electrical Engineer—Member of Staff, Satellite Design Department_ THE PROBLEM _It is hard enough to fix a new piece of scientific equipment when it goes out of order in the laboratory. And when the equipment is sailing around the earth a couple of thousand miles up in the sky a repair job ought to be impossible. But during the last two months of 1962 we found this not to be true at all. That was when the Telstar I satellite began to misbehave and eventually would not obey the commands we sent it from the ground. This presented us with a nice little problem: We had to find out exactly what was wrong with the satellite and then—the really tough job—devise a way to cure the trouble. We were able, finally, to do both these things, after a combination of logical deduction, trial-and-error experimentation, and laboratory testing—plus a certain amount of plain good luck. Our “cure,” unfortunately, turned out to be only a temporary one, for our patient had a relapse some weeks later. However, the story of how we went about doing our never-before-attempted task should give you an idea of the things you have to improvise in the laboratory when an experiment doesn’t work out exactly as you had planned._ The Telstar Command Circuit