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Washington, D.C.

The subcommittee met at 9 a.m., in room 214-B, Longworth House Office Building, the Hon. Joseph E. Karth, a member of the subcommittee, presiding.

Mr. KARTH. The meeting will come to order.

First of all, the subcommittee would like to recognize and welcome to the committee hearing this morning Astronaut Gordon Cooper. We are very happy that you could be with us. We appreciate your attending this hearing. If there is any speech you would like to make, now is the time to make it.

Major COOPER. No, thank you, sir.

Mr. KARTH. It is very nice to have you, sir.

Mr. Nicks, when we adjourned on Monday, we were about to take up the Hilburn Board recommendations and resultant actions that have been taken, and that I believe begins on page IV-10 of your testimony.

If you would care to proceed, we will follow you.

Mr. NICKS. Thank you, Mr. Chairman.


Mr. NICKS. I would like to start this morning with just a very brief introduction to pick up again where we left off. This chart (fig. 31, p. 114), shows the position of the Office of Space Sciences after the Ranger VI failure which led us to these reviews that we will be discussing.

Our first efforts were intended to find the faulty element, elements, or direct causes, and fix them if at all possible, to make overall modifications to the system to preclude this kind of failure, to do appropriate testing of the modified system so that we were certain the changes made were improvements and not detriments, and to instrument better to understand such failure if they were recurrent.

The better instrumentation requirement called for a different allocation of the telemetry channels to this particular aspect of the total system, so that if failures occurred in this region we would be able to find them.







NASA SL 3311-3.64


Now, the three review groups established at the time of this failure included two at JPL, one, a project board, and the other an independent JPL technical team; the third one being a NASA Headquarters Board under Mr. Hilburn, which you have heard about.

The conclusions of the JPL groups, taking into account the reviews that they made in conjunction with the headquarters-sponsored group resulted in the total report that was discussed in the testimony Monday.

Mr. KARTH. Are you going to further discuss those items that were on the chart just shown as you go through the remainder of your testimony, or should we do that at this time? If you feel you are going to answer them as you go through the Hilburn recommendations, fine. If not, I would like to ask them at this point. Mr. NICKS. Perhaps we should do that first.

Mr. KARTH. Will the operator put the slide back, please?

I wonder if you could address yourself to the first item on the slide, "find faulty element, telemetry elements, or direct causes and fix." I wonder if you could tell us what faulty element or elements you found, what direct causes you attribute to those faulty elements and what the fixes might be?

Mr. CORTRIGHT. Mr. Chairman, we had a little breakdown in communications here. I have been over this material, of course, with Mr. Nicks, and I believe that most of your questions will be answered, and it would be more convenient for the subcommittee if we did go

through the detailed review of what was found and what is being done about it, first, if you would just as soon do that.

Mr. KARTH. It really makes no difference to me, if you care to proceed.

Mr. NICKS. A number of specific design changes to the TV package were developed by JPL and RCA as a result of analyses of the Ranger VI flight data. These changes as enumerated below are concurred in by Office of Space Sciences and Applications and the Board.

(a) Modify the TV turn-on circuitry to provide a positive lock out of the turn-on signal until after spacecraft separation from the launch vehicle, to desensitize the turn-on circuitry, to eliminate the four-step switch, and to provide fault protection between the several turn-on signals.

Because of questioning the day before yesterday on this switch and the turn-on circuitry, I would like to have Mr. Schurmeier show you, with the aid of a view graph, (fig. 32) the possible ways of turning

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on the circuitry as it existed in Ranger VI. I think it will be helpful in understanding this redundancy question and the other aspects of it. Mr. KARTH. Before you do this, let me ask whether or not the Kelley Board or anyone else had, prior to Ranger VI, brought to your attention some of these problems that you will now attempt to correct after the Ranger VI flight?

Mr. NICKS. The Kelley report dealt pretty much with the spacecraft operation and not too deeply into the television system. I don't know of any specific reviews or hearings or directives about the circuitry before the flight. Do you, Bud?

Mr. SCHURMEIER. Well, the Kelley Board brought up in their review a number of general points that should be considered in the

design review effort that we embarked on. These were all carefully considered in the design review process.

Mr. KARTH. Thank you. You may proceed, Mr. Schurmeier.

Mr. SCHURMEIER. I think we may have gotten a little bit of a misinterpretation in the discussion on Monday in that the impression probably was that the only way to turn on both sides of the TV subsystem were through this rotary switch which, as we pointed out, was a single rotary switch.

If you will look at this figure, you can see that the side that has two cameras, and the transmitters-this one half of the TV system-has three modes or methods of turn-on.

One is the central controller and sequencer, which is the on-board control system. The second is this rotary switch which we spoke about, and a third independent subsystem, which is a clock-an on-board timer.

Now, the clock is started by the act of separation from the Agena, so that it is entirely independent of the spacecraft functions at that time. All it does is derive its power from the spacecraft.

Both the rotary switch and the C.C. & S. are controlled by ground commands, although at different times in the flight sequence. The other half of the TV subsystem, which consisted of the four cameras and associated transmitters, were controlled by the C.C. & S. and/or the rotary switch.

The other point that we would like to make is that there was some discussion of whether we considered dual rotary switches, different commands, and things like that.

In the process of this design review effort, many of these things were considered-different ground commands, two rotary switches, things of this nature.

After carefully considering all of these things, this is the configuration that was arrived at as a result of this design review process. Mr. NICKS. Shall I proceed?

Mr. KARTH. This is what you had in Ranger VI, is that right, Mr. Schurmeier?

Mr. SCHURMEIER. Yes, sir.

Mr. KARTH. Do you contemplate changing this for Ranger 7, and, if so, in what way?

Mr. SCHURMEIER. Yes; what we contemplate doing for Ranger 7 is to replace the rotary switch with a different sort of control logic. We are going to use relay logic in place of this rotary switch.

Now, the way we are doing this is by bringing into play an additional ground command-a real time command.

The reason the rotary switch was employed is that only one single command was available to be used for this, and therefore we had to step the rotary switch around to turn it on, to turn it into different modes, and to turn it off.

By reprograming things we are going to make use of additional ground command so that we have one ground command to turn it on and an additional one to turn it off.

The clock will basically be the same. The C.C. & S. will essentially be the same.

Mr. DOWNING. When is Ranger 7 scheduled for launch?

Mr. SCHURMEIER. It is presently scheduled for the latter part of June.

Mr. KARTH. Do you contemplate that the switch change you expect to make in Ranger 7 would eliminate the problem area that we found in Ranger VI? And by how much does this improve the reliability of the camera system?

Mr. SCHURMEIER. It is not really the switch change, and I can't give you at this point a quantitative number, that it increases it by 10 or 15 percent. I think it is a very good and worthwhile change to put in. Whether it will eliminate the failure, we can't absolutely say, because we have not been able to track down to a precise component exactly what failed. We think it covers one of the likely or probable failure modes.

Mr. KARTH. Is this an advanced state-of-the art change, or is this something that was well within the state of the art prior to Ranger VI? If, so why didn't we change it before?

Mr. SCHURMEIER. Well, I would say it is not a major state-of-the-art change. In all of this process, one makes a series of tradeoffs of the design changes, relative reliability items, and things of this type.

Mr. KARTH. Do you mean the change would have an advantage? If so, what is it?

Mr. SCHURMEIER. I didn't mean it in that term. I meant it in terms one is always changing or trading off in terms of the change in view of its reliability and its cost and its schedule implications.

Mr. KARTH. Is this a costly change?

Mr. SCHURMEIER. Well, it is costly not so much in the hardware as it is in the whole schedule of activities of the testing and the schedules of those things. This is where in other words, replacing the control switch by itself with the relay logic, and control logic, the cost is not so much in the actual components as it is in the redesign and requalification that is required.

Mr. KARTH. Was this one of the design or component deficiencies pointed out in the Kelley report?

Mr. SCHURMEIER. No, sir, and again the purpose of these changes are an attempt to prevent a possible inadvertent turnon because, as has been pointed out, this is what we believe is the probable failure mode of the TV subsystem.

Mr. KARTH. Now, what could have caused the inadvertent turnon? Mr. SCHURMEIER. There are a number of possible causes. You can get a short, theoretically, in any one of a number of places in any complex electrical system which could have caused the turnon. Possibly an electrical transient of some sort could possibly trigger the circuitry and turn it on. These are the-in general terms-the types of things that could cause this inadvertent turnon.

Mr. KARTH. Could floating debris, for example, have turned it on? Mr. SCHURMEIER. Floating debris is a possibility, if it would short in a particular spot.

Mr. KARTH. Had this system received considerable testing, via a tumbling procedure prior to launching of Ranger VI?

Mr. SCHURMEIER. No; the tumbling of the spacecraft is a very difficult task to accomplish. The boxes get vibration tests to check them out, and we closely monitor these things during vibration to see whether there are inadvertent shorts.

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