The Command Center

With the momentum from Kennedy's speech, their head start, and the enthusiasm of an exciting project, NASA and the IL refined an initial statement of work, laying out their vision for the Apollo guidance system. Written during the early Mercury flights in August 1961, the statement built on and refined the Mercury approach toward automation and the pilots' roles. Again, in keeping with the IL engineering culture, they stipulated that navigation be autonomous, that ''the primary command and decision making responsibility shall be on board the spacecraft.'' That is, the astronauts should be able to complete the mission with no guidance or information from the ground, although they might wish to incorporate such data ''to increase reliability, accuracy, and performance.'' Second, the crew was to control or direct the spacecraft during all flight modes. Despite this manual control, the statement noted, automatic systems should still be employed, ''to obtain precision, speed of response, or to relieve the crew of tedious tasks; but crew monitoring of these systems with provisions for crew override or mode selection is required.''

Emphasizing human control of the mission, NASA described the capsule for the astronauts as a ''command center'' (later officially the ''command module''). It was to include ''features which allow effective crew participation,'' such as windows, equipment that could be maintained in flight, and ''simple, manually operated functions in lieu of complex automation.'' Means were to be included to allow the ''pilot'' to control the attitude of the spacecraft by hand. The work statement also called for ''direct electrical control of the valves''—that is, the astronauts would be able to control the thrusters without mediation by the computer (several astronauts expressed desires for even more direct mechanical—as opposed to electrical—connection to the thrusters. They lost: unlike aircraft, Apollo would not have control cables). In an attempt to use the latest media technology to document the project, the contractor was to provide quarterly reports and submit color 16-mm motion picture films of the highlights of the program.46

This original idea also included two elements that would not survive into the final version; both reflect changing ideas of the astronauts' roles. A ''map and data viewer'' was to be a database, like a microfilm-based server, allowing the astronaut to call up ''thousands of different frames of information, very high information density,'' including lunar features, star charts, and procedures for operating and repairing the equip ment, a ''combination road-map, almanac, and manual of special instructions.''47 Were the spacecraft navigated in a truly autonomous mode, such information would have been necessary and the map and data viewer an efficient way of reducing weight and bulk.

But as Apollo evolved, controllers on the ground assumed greater real-time input into the mission. Close cooperation with the ground eroded the need for autonomy in orbit, and the vast amount of reference materials moved to the other side of the radio link. Indeed, complementing mission control in Houston were large numbers of engineers poring over charts, manuals, specifications, and calculations. In general, the pilots did not have huge data books cluttering up the spacecraft (unlike aircraft pilots who shared their cockpits with navigational charts and books of procedures). The reference data for troubleshooting was to come from the ground, and the astronauts survived on a rather small number of checklists, timelines, and emergency trajectory data.

The onboard teleprinter also would not survive the design process. It was to allow commands and coordinates from the ground to be uplinked and printed out in the cockpit. The idea was to save time, particularly at critical moments such as when the LM emerged from the far side of the moon, and needed a quick navigation update before descending to the lunar surface. Flight Director Chris Kraft strongly advocated for the printer as an error-free way to get data and commands up to the pilots, but Deke Slayton, NASA director of Flight Crew Operations (informally the ''Astronaut Office'') killed the idea.48

Throughout Apollo, instead of reading numbers off the teleprinter, the astronauts would listen to numbers from the ground, write them down, read them back for verification, and then enter them into the computer (a process that took several minutes for a good navigational update). Human hearing replaced the technical printer (the state vector could also be digitally updated from a ground telemetry link). These techniques were more time consuming and error-prone than a simple printer, but they did save a few pounds of weight. One result of this decision meant that the Apollo voice links provide a particularly rich record of the flights. Even in these small technical choices engineering trade-offs between human and machine embedded in the very early stages of the project.

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  • regina mugwort
    What can astronauts report to the command center?
    3 years ago

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