At each Deep-Space Instrumentation Facility (DSIF) the spacecraft telemetry and video data transmitted from the spacecraft was recorded, displayed for internal requirements, and processed for transmission to the JPL Space Flight Operations Facility (SFOF). Approximately 260 items were available on the spacecraft as commutated data to provide information on the condition of the spacecraft subsystems. This data was available from any of seven commutator word-frame configurations (15 to 117 words per frame) at selectable bit rates of from 17.2 to 4400 bits per second. In the event telemetry data or video was not present at the SFOF because of earth transmission or processing difficulties, an analysis was available at the DSIF from the crew of the command and data-handling console (CDC) upon request.

Video data was displayed on monitors at each command and data-handling console, but only the video data received at Goldstone was transmitted by microwave to the SFOF in real-time. In addition to magnetic tape recordings of telemetry and video at each of the receiving sites and at the SFOF, high-quality 70-millimeter film recordings of each frame of video were made at Goldstone and at the SFOF as video was received.

Spacecraft command was accomplished by voice instructions to the Surveyor operations chief of the command and data-handling console, where either prepared punched tape or manual inputs could be made for the transmitter. Punched command tapes were used in a tape reader at the command and datahandling console whenever long command sequences were required that were repeated many times. Commands could be transmitted as desired at one-half-second intervals. Outgoing commands were relayed back to the SFOF for confirmation of the requested transmission.

Mission Operations System

The mission operations system was organized to carry out the project operational functions of:

1. Continuous assessment and evaluation of mission status and performance

2. Determination and implementation of appropriate command sequences required to maintain spacecraft control and to carry out desired spacecraft operations during transit and while on the lunar surface.

In addition to support for the areas of data acquisition, data processing, and communications, three groups of space flight specialists provided technical support under the space-flight operations director (SFOD) in the areas of flight-path analysis, spacecraft performance, and spacecraft science.

Flight-Path Analysis and Command Group

The flight-path analysis and command (FPAC) group handled those space flight functions that related to the location of the spacecraft. The FPAC group made specific recommendations for maneuvers and generated the specific command requirements to effect their accomplishment. Five subgroups of specialists covered trajectory, tracking data, orbit determination, maneuver analysis, and computer-support functions.

Spacecraft-Performance Analysis and Command Group

The spacecraft-performance analysis and command (SPAC) group was responsible for the operation of the spacecraft itself. The SPAC group implemented commands for all functions other than science payload. They determined response to commands, spacecraft status, and performance of the basic spacecraft. Four subgroups of specialists covered performance analysis, command preparation and control, computer support, and failure analysis.

Space-Science Analysis and Command Group

The space-science analysis and command (SSAC) group performed those functions that related to the operation of the scientific payload, television camera, surface sampler, and alpha-scattering instrument. Each instrument

was supported by a team composed of two subgroups: a performance-analysis group, who were concerned with the performance and analysis of the instrument from an engineering aspect, and a science-analysis group, who were concerned with data requirements and results from a scientific viewpoint. In addition to these instrument teams, there were specialists covering computer support, DSIF command communications, videorecording coordination, and log-keeping.

The SSAC director operated from a control station at the center rear of the science operations area and had his support specialists and instrument teams to either side and in front of him. The television team was immediately in front of the SSAC director with special video and computer data displays for performance-data analysis. Directly at the front of the science operations area were located slow-scan television monitors with cameras for rapid, hard-copy photo acquisi

tion, the mosaicing teams for panorama mosaic construction, and a large wallboard displaying television-camera parameters. The surface sampler team were located to the SSAC director's right; to his left were the command controller and video-recording coordinator/log-keeper. The alpha-scattering team took over the television team's stations when the alpha-scattering instrument was operated because the two instruments could not send back data simultaneously.

The head of each instrument group reported analysis results and recommendations directly to the SSAC director (on a personal, verbal basis). Command requirements for utilization of each instrument were submitted on a command form (figs. 3, 4, and 5), which, after implementation, became a record of action taken.

Authority to send commands to the spacecraft rested with the space-flight operations director and was delegated to the

SSAC director as long as the scope of endeavor was within the planned sequence of events. Deviation from standard procedures or sequences required approval by the spaceflight operations director. The task of briefing and directing the Surveyor operations chief was performed by the command director via voice communications under the direction of the SSAC director. Within the SSAC area, intergroup activities were primarily on a faceto-face relationship, but local intercom facilities were also used. Contact with groups outside the SSAC area was by intercom voice network.

Spacecraft Operations

The daily operations cycle started with the Goldstone view period and continued through the two DSIF view periods that followed (Australia and Spain) until Goldstone again resumed control. During the lunar operations phase, an operational plan was developed daily on the requirements for that day's efforts as an update of the prelaunch lunar operations plan. Two hours before each Goldstone rise, an operations planning meeting was held at which the operating requirements for the following period were developed. The project scientist submitted the day's requirements at this time, based upon detailed analysis (by investigator teams) of data acquired from preceding operating periods. Instrument requirements were considered in their proper perspective along with basic spacecraft housekeeping needs and data requirements from the various spacecraft subsystems. Following this meeting, the space-flight operations director and the SPAC and SSAC directors developed specific technical area plans for the three DSIF view periods that followed.

The SSAC group's detailed planning required fitting the various instrument requirements into the most efficient sequences with as much as possible of the command strings worked out ahead of time. The alphascattering instrument and surface sampler were relatively easy to plan for once the gen

eral objectives were decided upon since, in most cases, operations had to be determined in real-time based upon preceding results. Although this was also true to a large extent in the case of television, many of the commands required for a series of specific pictures could be worked out ahead of time.

Television operations requiring real-time analysis support could only be conducted during Goldstone reception because video was not available to JPL from overseas stations, although it was available at any receiving station for its own viewing. Some TV was managed during overseas visibility when the efforts were routine, the requirements could be defined in detail, and the data could be acquired with limited analysis by station personnel or with support from SSAC based upon a verbal description of the overseas video reception. Since TV support was necessary to monitor the surface sampler, it could only be operated during Goldstone reception. On the other hand, since alphascattering data was available in the SFOF from any of the three DSIF stations, that instrument could be operated at any time instrument temperatures permitted.

Prior to each DSIF moonrise, all applicable support areas of the mission operations system confirmed their readiness to support operations by completing a standard countdown that exercised or calibrated all dataacquisition, processing, recording, and display equipment. In addition to normal preparations to receive and to process telemetry data, special precautions were taken to support TV data acquisition. Video test patterns, conforming to the last-measured spacecraft parameters, were fed through the complete video system from receiver to recordingand-display equipments. In the case of Goldstone reception, this involved the video microwave transmission system and the Surveyor television ground data-handling system (TVGDHS) with support from the SSAC video analyst to measure system performance and to assure that the system would be adequate for reception of spacecraft video.

Real-time data arrived at the SFOF via microwave (Goldstone video only), high-speed