The Shepard Training Diagram
Before Alan Shepard flew his historic 1961 suborbital mission on Freedom 7, he had to learn how to operate his spacecraft. This simple photographic chart, which is 75 cm (29.5 in.) high and a bit over a meter (40 in.) wide, helped him memorize the layout of his instrument panel. The very simplicity of this training aid and of the instruments it represents provides a window on the earliest days of U.S. human spaceflight. The rather crude aid highlighted a central feature of Freedom 7's cockpit instrumentation: It was sparse, even compared to later Project Mercury orbital flights. Still, this simplicity can be misleading; the Mercury capsule was a complicated piece of machinery requiring equally elaborate training.
This diagram is labeled "Capsule 7" because Shepard's was the seventh spacecraft in the series. It shows the four main panels in front of the astronaut. The most noticeable feature (represented in bottom center) is the large circular screen used to display images from a periscope that looked outside the capsule-this provided Shepard's main view. In the original Mercury design, two small portholes also provided an exterior view, but a very limited one. The astronauts fought against the porthole concept and won a rectangular window in front of the astronaut's head-an intervention later made famous by Tom Wolfe's book The Right Stuff. Shepard, however, flew the last of the porthole-equipped capsules, so that during his brief time in suborbital transit through space, the periscope provided his only effective view of the Earth from a hundred miles up. But the view was "beautiful," leading him to describe cloud cover on the East Coast and the islands and reefs of the Bahamas.
Other instruments in the center panel provided basic orientation. A clock, along with a time counter in seconds, provided the time and the mission elapsed time-on a fifteen-minute mission he did not need to count hours, or even minutes, from launch. At the top of the panel there are three needles giving the orientation of the capsule in roll, pitch and yaw. At upper left on the center panel is a gauge giving acceleration and deceleration forces in "g's"-multiples of the Earth's gravitation pull. Shepard and all the early astronauts endured extremely heavy forces: eight "g's" on the way up and eleven coming back down. Finally, for the parachute descent of his capsule into the ocean, Shepard had an altimeter and a rate of descent gauge.
The far right panel provided fundamental information on the cabin atmosphere and cooling, on the capsule's batteries and electrical power, plus controls for the radios. Immediately to the left of the main panel are lights for various important functions such as separation of the capsule from the booster, retrofire and parachute deployment. They would light green when things worked; red when they did not. To the left are switches for manually overriding these critical functions, on which Shepard's life depended. Finally, switches and the gauge on the left provided control over cabin lights and the attitude control system. Shepard had two independent attitude control systems and two sets of control jets. A control stick in his right hand, not shown in the diagram, provided the mechanism for changing the attitude of his capsule in space by commanding the firing of the jets.
After his flight, Alan Shepard hung on to this poster-board diagram as a souvenir before giving it to the Smithsonian in fall 1965. Upon doing so, he signed it, making it an even more valuable artifact of the earliest days of humans in space.
