The LM Crew Station: Standing Room Only on the Moon
How Grumman designed a cockpit with no seats, triangular windows, and an instrument panel for two astronauts flying a spacecraft they could see through
The Lunar Module’s crew cabin was 92 cubic feet of pressurized volume—roughly the interior of a large closet. Two astronauts stood side by side in a space about 7.5 feet across and 3.5 feet deep, wearing bulky pressure suits, facing an instrument panel dense with switches, circuit breakers, and displays. There were no seats. There was no floor in the conventional sense—just a flat deck that served as the cabin floor during powered flight and the ceiling of the equipment bay below. The walls were thin enough to puncture with a ballpoint pen. And through two small triangular windows, the crew watched the lunar surface rise toward them during the most consequential twelve minutes of the mission.
The Cabin: Pressure Vessel as Cockpit
The ascent stage cabin was a cylindrical pressure vessel approximately 92 inches in diameter, pressurized to 4.8 psi with a pure oxygen atmosphere. The cabin walls were aluminum alloy, chemically milled to thicknesses as low as 0.012 inches in lightly loaded areas—about the thickness of three sheets of heavy paper. In higher-stress areas around window frames, hatch edges, and structural attachments, the walls were thicker, up to 0.063 inches.
The cabin was not designed for comfort. It was designed to be the lightest possible pressure-tight enclosure that could keep two humans alive for the duration of the LM’s mission—typically 40 to 75 hours from undocking to redocking, depending on the mission. There was no insulation on the interior walls; the crew could feel the thermal variations as sunlight struck or left the outer surfaces. There were no creature comforts—no galley, no lavatory, no sleeping accommodations beyond the ability to curl up on the engine cover between the two crew stations and nap in zero gravity.
The floor—the crew’s working surface during descent and ascent—was the top of the mid-section that housed the ascent engine. The ascent engine’s combustion chamber protruded up into the cabin space, covered by a flat engine cover that doubled as a work surface and a rest area. The engine cover was directly between and behind the two crew positions, and the crew literally stood on top of the engine that would later launch them off the Moon.
The Windows: Triangular Fields of View
The LM had two forward-facing windows, one for each crew member, angled outward and downward to provide a view of the terrain during landing. The windows were roughly triangular in shape—an unusual geometry driven by the structural analysis of the pressure vessel. A triangular window opening required less structural reinforcement than a rectangular one of similar area, saving weight in the window frames while providing adequate visibility.
Each window was a dual-pane assembly. The inner pane was a structural element—part of the pressure vessel—made of chemically tempered glass about 0.29 inches thick. The outer pane was a protective layer that shielded the inner pane from micrometeorite damage and thermal stress. Between the panes was a sealed air gap for thermal insulation.
The commander’s left window and the LM Pilot’s right window were angled at different orientations to serve different functions during the landing. The commander’s window was oriented to provide a downward view during the approach phase—critical for the Landing Point Designator, which used graduated markings on the window frame to show where the guidance computer was targeting. The LM Pilot’s window provided a more lateral view.
Both windows were coated with an anti-reflective treatment on the interior surface to reduce glare from cabin lighting and instrument panel illumination. During the descent, the cabin lights were dimmed to minimize reflections, and the crew relied on the external scene and the DSKY for situational awareness.
A small overhead docking window was located at the top of the cabin, directly above the docking hatch. This window allowed the commander to see the Command Module’s docking target during the rendezvous and docking maneuver. The docking window was also fitted with a reticle—alignment marks that the commander used to visually verify the docking alignment as the two vehicles closed.
The Instrument Panel: Every Switch Matters
The LM instrument panel was arranged in a U-shape around the two crew positions. The center panel, directly ahead, contained the primary flight instruments and the DSKY. The left panel (commander’s side) held the propulsion, electrical power, and environmental control system switches. The right panel (LM Pilot’s side) held the communications, abort guidance, and systems monitoring controls. Overhead panels contained circuit breakers and lighting controls.
The center panel’s layout reflected the priorities of the landing phase. The Attitude Director Indicator—the “8-ball,” an artificial horizon instrument similar to those in aircraft—was positioned at eye level between the two crew positions. The DSKY was below it, accessible to both crew members. The Flight Director Attitude Indicator displayed the spacecraft’s current attitude relative to the guidance platform, and the cross-pointer displays showed horizontal velocity components during the landing.
The cross-pointer display was particularly important during the final descent. It showed forward and lateral velocity as deflections of two needles from center—a centered display meant the LM was descending vertically with no horizontal drift. The commander used this display, along with the out-the-window view, to null horizontal velocities before touchdown.
The control interfaces were divided between the crew. The commander had the primary attitude hand controller (a three-axis pistol grip on the right armrest) and the thrust/translation controller (a T-handle on the left armrest). The LM Pilot had a matching set of controllers on his side, providing redundant capability—if the commander was incapacitated, the LMP could fly the vehicle.
The ABORT button and ABORT STAGE button were on the instrument panel, accessible to both crew members. ABORT commanded the descent engine to fire at full thrust to return to orbit. ABORT STAGE fired the staging pyrotechnics, separated the ascent stage, and ignited the ascent engine. These were one-press emergency actions designed for immediate response—no confirmation dialog, no “are you sure?” prompt. Press the button, and the abort executed.
Standing Versus Sitting: The Ergonomics of Weightlessness
The decision to eliminate seats and have the crew stand was driven by SWIP’s weight reduction mandate, but it turned out to have ergonomic advantages that a seated cockpit wouldn’t have provided.
In the one-sixth gravity of the Moon, standing required minimal effort—each crew member weighed roughly 60 pounds in his suit, about the same as leaning against a wall on Earth. The restraint system consisted of simple Velcro straps and fabric cables attached to the floor and walls, supplemented by a pair of armrests for each crew member that helped stabilize them during dynamic phases. The crew could shift their weight, lean forward to look out the windows, or lean back to reach overhead panels with an ease that a seated position would have constrained.
During zero-gravity phases (coast to and from the Moon, orbital operations), the standing configuration was essentially meaningless—the crew floated. They could orient themselves in any direction, and the restraint system kept them loosely positioned in front of their respective panels during operations that required panel access.
The standing position placed the crew’s eyes closer to the windows and higher in the cabin than seats would have. This improved the downward viewing angle during landing—a critical advantage because the commander needed to see the terrain directly below and ahead during the final approach. A seated commander would have been lower, with less window area providing useful terrain visibility.
The primary ergonomic challenge of the standing cockpit was fatigue during long periods of activity. The crew were in their suits for the entire landing sequence—from undocking through landing, surface operations, ascent, and redocking. During the powered descent (12 minutes) and the EVA preparation and execution (5-7 hours on later missions), the crew were continuously active. The standing position, even in low gravity, contributed to fatigue in the legs and feet. Astronauts on later missions reported that the foot restraints could be uncomfortable during extended wear.
The Hatches: Getting In and Getting Out
The crew station had two hatches. The forward hatch, at the front of the cabin between the two crew positions, opened inward and provided access to the “porch” and ladder for lunar surface egress. The overhead docking hatch, at the top of the cabin, provided the transfer tunnel between the LM and the Command Module.
The forward hatch was deliberately small—about 32 inches square—to minimize the structural cutout in the pressure vessel. Getting through it in a pressurized suit with a backpack was an exercise in contortion that every crew member practiced extensively. The astronaut knelt on the cabin floor, backed toward the hatch opening, ducked under the hatch frame, and crawled onto the porch on hands and knees. The process took several minutes and required the cabin to be depressurized first, since the hatch opened inward against the cabin pressure.
The overhead docking hatch was used for crew transfer between the LM and CM. After docking, the probe and drogue mechanism that connected the two vehicles was removed, exposing the transfer tunnel. The crew floated through the tunnel headfirst, transitioning from one vehicle to the other. The docking hatch had to seal pressure-tight from both sides—it maintained the LM’s cabin pressure during undocked operations and sealed the transfer tunnel during docked operations.
Both hatches were opened and closed dozens of times during development testing and crew training. The sealing surfaces were inspected before every flight for scratches, dents, or contamination that could cause a pressure leak. A hatch seal failure in the lunar vacuum would be immediately catastrophic—cabin pressure would drop to zero in seconds, and the crew’s suit integrity would be their only protection.
Cabin Atmosphere and the Smell of the Moon
The LM cabin was pressurized with pure oxygen at 4.8 psi—about one-third of sea-level atmospheric pressure but with a higher oxygen partial pressure than normal air, providing adequate respiration. The Environmental Control System maintained the cabin temperature, humidity, and carbon dioxide levels within livable ranges throughout the mission.
After the EVA, when the crew returned to the cabin and repressurized, they brought lunar dust with them. The fine, abrasive regolith clung to their suits, boots, and gloves, and once the cabin repressurized, the dust became airborne in the confined space. Every crew that walked on the Moon reported a distinctive smell when they removed their helmets after the EVA—a sharp, acrid odor variously described as “spent gunpowder,” “burnt charcoal,” or “the smell after a firecracker.” The smell was believed to be caused by the oxidation of iron-rich minerals in the regolith when exposed to the cabin’s oxygen atmosphere for the first time.
The dust was more than an olfactory novelty. It was abrasive enough to scratch optical surfaces, clog equipment, and irritate the crew’s eyes and respiratory systems. Apollo 17’s Harrison Schmitt, a geologist, experienced what he described as “lunar hay fever” after prolonged exposure to the dust in the cabin. The confined crew station—small volume, recirculated air, dust clinging to every surface—concentrated the exposure.
A Cockpit for a Different World
The LM crew station was unlike any cockpit before or since. It was designed for a vehicle that flew in vacuum, landed on another world, and never returned to Earth. It had no aerodynamic instruments because there was no atmosphere. It had no runway in the windscreen because there was no runway. The pilot’s view was a stark landscape of gray regolith, black sky, and harsh shadows—a visual environment that human eyes had never evolved to process and that no amount of simulator training could fully replicate.
Twelve astronauts stood in that cabin during powered descent and watched the Moon fill their windows. They stood because sitting would have weighed too much. They looked through triangular windows because triangles were lighter than rectangles. They read instruments from a panel designed by engineers who balanced every gram of metal against every degree of visibility and every inch of reach. It was cramped, utilitarian, and stripped of every non-essential feature. It was exactly what it needed to be—a place to stand while landing on the Moon.