Some lunar mission earth orbit phase ground rules

See list belowAPR 8 196868-PA-T-73APA/Chief, Apollo Data Priority CoordinationSome lunar mission earth orbit phase ground rules

1. I would like to make sure everyone is aware of some important decisions which were made at Ron Berry's Midcourse Phase Mission Techniques meeting on April 3. They have to do with operations during the earth parking orbit phase prior to TLI on a lunar mission.

2. Current planning involves performing the TLI maneuvers at the first opportunity. For Atlantic injection, this can occur approximately one and a half hours after launch. It is important that the efforts of all the organizations be in accordance with that. If it is determined that some activity precludes TLI this soon, the responsible organization should make this known immediately. As noted previously, it has been established that no spacecraft platform alignment is required prior to the first opportunity TLI, which helps the crew time line.

3. One component of the go/no go for the first TLI opportunity is valida- tion of the S-IVB IU state vector. Since during the first revolution we are unable to generate an MSFN state vector superior to the anticipated IU's, the check can only be gross. The actual parameter to be tested will be magnitude of the anticipated midcourse correction. The criteria will be based on how well we will be able to determine right from wrong rather than on reasonable magnitude of the midcourse correction, we would be willing to accept operationally. It will be a function of MSFN tracking coverage available prior to the go/no go decision.

4. In order to avoid having to make unnecessary real-time decisions, in addition to all the associated pre-flight analysis and arguments to establish the decision logic, we have established the following ground rules:

a. We will never transmit a state vector update to the S-IVB IU for the first TLI opportunity.

b. We will always transmit a state vector update to the S-IVB IU for the second TLI opportunity.

c. We will always transmit a state vector update to the CSM G&N for the first TLI opportunity. The state vector to be sent to the CSM will be obtained via telemetry from the S-IVB IU.

The Intention, of course, is to always use the best state vector. During the first revolution, the IU state vector should be superior to any other source and should be acceptable for use. Thus, there will be no reason to update the IU and no reason not to update the G&N. During the second revolution we can be certain the MSFN state vector will be adequate for guiding through the second TLI opportunity – at least as good as, or better than the S-IVB IU state vector – which means no harm is done by sending a state vector update, but it can improve the situation. There is reason to suspect that MSFC may not approve this ground rule (b) but it seems to me the burden of proving why we should do something else is on them.

5. All of this will be documented in detail in the minutes of the meeting. I hope the chairman will excuse my scooping him, but I felt it desirable to advertize and emphasize these things since they have a significant influence in the procedures we are implementing and you should all be aware of them.