Apollo spacecraft

Spacecraft Modules

The Apollo spacecraft was designed as part of the Apollo Program, by the United States in the early 1960's to land people on the moon before 1970 and return them safely to earth. It was made up of multiple units or modules that worked together to perform the mission of landing on the moon and returning to earth. The main parts of the Apollo spacecraft were (going from top to bottom) the launch escape system, the Command Module, the Service Module, the Lunar Module and the lunar module adapter.

In the early 1960's it was decided there were three main ways to reach the moon and return to earth.

• 1. Direct Ascent. A very large rocket would be launched from earth carring a spacecraft directly to the moon. The entire spacecraft would land on the moon. A portion of the spacecraft would lift off the moon and return to earth.

• 2. Earth Orbit Rendezvous. Several smaller rockets would be launched, rendezvous in earth orbit and fuel a single spacecraft to travel to the moon. The spacecraft would fly to the moon and land. A portion of the spacecraft would lift off the moon and return to earth.

• 3.Lunar Orbit Rendezvous. A single smaller rocket would launch the spacecraft to the moon. The spacecraft would fly to the moon and orbit it. A smaller portion of the spacecraft would land on the moon and return to lunar orbit. Then a portion of the spacecraft would return to earth.

Each technique had its advantages and disadvantages. At the time rendezvous in space was a big unknown. It had not even been attempted in earth orbit.

• 1. Required a very large rocket, but didn't risk the unknowns of rendezvous.

• 2. Used smaller rockets, but required multiple launches and performed rendezvous close to earth.

• 3. Required only one smaller rocket, but performed the rendezvous in lunar orbit, far from earth.

The Apollo spacecraft was designed to land on the moon using option number three. It only needed a single smaller rocket and it was thought that orbital rendezvous could be perfected berore a lunar flight took place.

Launch vehicles: Little Joe II, Saturn I, Saturn IB, and Saturn V.

Launch Escape System (LES)

The purpose of the Apollo Launch Escape System was to pull the Command Module (which contained the crew cabin) rapidly away from any launch emergency.

The emergency could be a pad fire, exploding launch vehicle or a launch vehicle going off course.

The Launch Escape System would work automatically (or through manual activation) to fire a solid fuel escape rocket and open a canard system to direct the Command Module away from, and off the path of, a launch vehicle in trouble. The Launch Escape System would then jettison and the Command Module would land with its parachute recovery system.

If the emergency happend on the launch pad, the Launch Escape System would lift the Command Module to a sufficient height to allow the recovery parachutes to deploy safely.

• Major Components of the Launch Escape System (LES):
  • Nose Cone / "Q-Ball" - The "Q-Ball" contained sensors that determined the angle of attack and attitude of the spacecraft and launch vehicle. It relayed this information to the spacecraft and the launch vehicle guidance system.
  • Canard Assembly - Pitch Motor - These worked in combination to direct the Command Module off a straight path and to the side during an emergency. This would direct the Command Module off the flight path of an exploding launch vehicle. It would also direct the Command Module to land off to the side of any launch pad fire and not land back in the middle of it.
  • Tower Jettison Motor - A smaller solid fuel motor that jettisons the Launch Escape System after it is no longer needed. This usually happens after second stage ignition.
  • Launch Escape Motor - The main solid fuel rocket motor that, firing through four rocket nozzles, pulls the Command Module rapidly away from a launch emergency.
  • Launch Escape Tower - Assemlby that attaches the Launch Escape System rocket motors to the Command Module.
  • Boost Protective Cover - Hollow cone shaped structure that fits over the Command Module during launch. It protects the Command Module heat shield and windows during ascent through the atmosphere. It also protects the Command Module from rocket exhaust should the Launch Escape System fire.

• Specifications:
  • Total Length: 10.2 m
  • Diameter: 0.66 m
  • Total mass: 4,173 kg
  • Thrust: 155,000 lbf (689 kN)

Command Module (CM)

The Command Module was the control center for the Apollo spacecraft and living quarters for the crew. It contained the pressurized main crew cabin, crew couches, control and instrument panel, optical and electronic guidance systems, communications systems, environmental control system, batteries, heat shield, reaction control system, foward docking hatch, side hatch, five windows and the parachute recovery system.

• • Specifications:
    • Crew: 3
    • Crew cabin volume: 6.17 m³
    • Length: 3.47 m
    • Diameter: 3.90 m
    • Mass: 5,806 kg
    • Structure Mass: 1,567 kg
    • Heat Shield Mass: 848 kg
    • RCS Mass: 400 kg
    • Recovery Equipment Mass: 245 kg
    • Navigation Equipment Mass: 505 kg
    • Telemetry Equipment Mass: 200 kg
    • Electrical Equipment Mass: 700 kg
    • Communications Systems Mass: 100 kg
    • Crew Couches and Provisions Mass: 550 kg
    • Environmental Control System Mass: 200 kg
    • Mis. Contingency Mass: 200 kg
    • RCS Thrust: 12 x 420 N
    • RCS Propellants: N2O4/UDMH
    • RCS Engine Propellants: 75 kg
    • RCS Isp: 290 lbf.s/lb (2.84 kNs/kg)
    • RCS Impulse: 257 kNs
    • Electric System Batteries: 20.0 kWh, 1,000.0 Ah

Service Module (SM)

The Service Module was a portion of the spacecraft that is unpressurized and contains fuel cells, batteries, high gain antenna, radiators, water, oxygen, hydrogen, reaction control system, propellant to enter and leave lunar orbit, and service propulsion system. On Apollo 15, 16 and 17 it also carried a scientific instrument package, mapping camera and a small sub-satellite to study the moon.

A major portion of the service module is taken up by propellant and the main rocket engine that placed the Apollo spacecraft into and out of lunar orbit. The main rocket engine was also used for mid-course corrections between the earth and the moon. It was capable of multiple restarts.

It remained attached to the Command Module throughout the mission. It is jettisoned just prior to reentry into the earth's atmosphere.

• • Specifications:
    • Length: 7.56 m
    • Diameter: 3.90 m
    • Mass: 24,523 kg
    • Structure Mass: 1,910 kg
    • Electrical Equipment Mass: 1,200 kg
    • RCS Thrust: 16 x 440 N
    • Propellants: N2O4/UDMH
    • RCS Isp: 290 lbf.s/lb (2.84 kNs/kg)
    • RCS Impulse: 3,517 kNs
    • Service Propulsion Engine (SPS) Engine Mass: 3,000 kg
    • SPS Engine Thrust: 98 kN
    • SPS Engine Propellants: N2O4/UDMH
    • SPS Engine Propellants: 18,413 kg
    • SPS Engine Isp: 314 lbf.s/lb (3.08 kNs/kg)
    • Spacecraft delta v: 2,804 m/s
    • Electrical System: Fuel Cells
    • Electric System: 6.30 average kW, 670.0 kWh

Lunar Module (LM)

The Lunar Module was the portion of the Apollo spacecraft that landed on the moon and returned to lunar orbit. It is divided into two major parts, the Descent Module and the Ascent Module.

The Descent Module contains the landing gear, landing radar antenna, descent rocket engine, and fuel to land on the moon. It also had several cargo compartments used to carry among other things, the Apollo Lunar Surface Experiment Packages ALSEP, Mobile Equipment Cart (a hand pulled equipment cart - Apollo 14) the Lunar Rover (moon car - Apollo 15, 16 and 17), surface television camera, surface tools and lunar sample collection boxes.

The Ascent Module contains the crew cabin, instrument panels, overhead hatch/docking port, forward hatch, optical and electronic guidance systems, reaction control system, radar and communications antennas, ascent rocket engine and fuel to return to lunar orbit and rendezvous with the Apollo Command and Service Modules.

• Specifications:
  • Ascent Stage:
    • Crew: 2
    • Crew cabin volume: 6.65 m³
    • Height: 3.54 m
    • Diameter: 4.27 m
    • Ascent Stage Mass: 4,547 kg
    • Ascent Engine Propellants: 2,358 kg
    • RCS Thrust: 16 X 440 kN
    • RCS Propellants: N2O4/UDMH
    • RCS Isp: 290 lbf.s/lb (2.84 kNs/kg)
    • Ascent Engine Thrust: 16 kN
    • Ascent Engine Propellants: N2O4/UDMH
    • Ascent Engine Engine Isp: 311 lbf.s/lb (3.05 kNs/kg)
    • Ascent Stage Delta V: 2,220 m/s
    • Electric System Batteries: 17.0 kWh 800.0 Ah

• • Descent Stage:
    • Height: 2.83 m
    • Diameter: 4.21 m
    • Landing Gear Diameter: 9.37 m
    • Descent Stage Mass: 10,149 kg
    • Descent Engine Propellants: 8,165 kg
    • Descent Engine Thrust: 44 kN
    • Descent Engine Propellants: N2O4/UDMH
    • Descent Engine Engine Isp: 311 lbf.s/lb (3.05 kNs/kg)
    • Descent Stage Delta V: 2,470 m/s
    • Electric System Batteries: 33.0 kWh, 1,600.0 Ah

Spacecraft Lunar Module Adapter (SLA)

The Spacecraft Lunar Module Adapter (SLA) is an aluminum cone shaped structure that connects the Service Module to the Saturn S-IVB rocket stage. It also protects the Lunar Module during launch and ascent throught the atmosphere. It is made up of four large panels that open from the top similar to flower petals.

The SLA is made from 42.5 mm thick aluminum honeycomb material. The exterior of the SLA is covered by a layer of cork nearly 1 mm thick and then painted white. The cork insulates the Lunar Module from atmospheric frictional heat generated durning launch and ascent.

Once in space, the Command and Service Module detach from the SLA. Then the four SLA panels are then opened and released from the S-IVB rocket stage. This uncovers and allows access to the Lunar Module. The Command and Service Module turns 180 degrees and docks with the Lunar Module and then pulls it free from the S-IVB rocket stage.

• Specifications:
  • Height: 28ft (8.5 m)
  • Diameter - Apex: 12 ft 10 in (3.9 m) Service Module end
  • Diameter - Base: 21 ft 8 in (3.85 m) S-IVB end
  • Weight: 4,050 lb (1,837 kg)
  • Volume: 6,700 ft³ (2,042 m³), 5,000 ft³ (1,524 m³) usable