vol 6, issue 10

Classic Projects - Apollo Lunar Module

17 October 2011
By Nick Smith
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Apollo Lunar Module

How the Lunar Module got off the ground

The first ever genuine 'space ship', the Apollo Lunar Module was a masterpiece of design.

Buzz Aldrin told E&T that he regards the Apollo 11 Lunar landing as one of the greatest feats of exploration ever achieved by mankind (http://bit.ly/buzz-interview). He also regarded it as the pinnacle of collaborative engineering, which would go down in history as the major response of 'two nations facing each other with threatening technologies, sometimes called mutually assured destruction'.

When Neil Armstrong descended the steps of Lunar Module Eagle on 20 July 1969, the so-called 'Space Race' was effectively ended. It had been a proxy war, with engineering, support, design and logistics teams the size of armies engaging in a symbolic conflict that ended with the bungled call signal that Apollo 11 had reached its destination of 'Tranquility Base'.

As a result of extensive rocket research during the Second World War it was known that the technology could be launched into Earth's orbit and beyond. But the question remained over how to get men from Lunar orbit to the surface of the Moon and back again.

There were options including direct ascent and Earth orbit rendezvous (EOR), but these were rejected in favour of Lunar orbit rendezvous (LOR). The next'step was to design a separate spacecraft that could make the landing and return to the command/service module (CSM).

Serious work on designing a landing craft didn't start until the early 1960s with the main player being American aerospace engineer Tom Kelly, of Grumman Aircraft Engineering, which was awarded the contract to supply the Lunar Module. Worth an estimated $350m, the project had four major subcontractors: Bell Aerosystems, Hamilton Standard, Marquardt and Rocketdyne.

One of the key concerns in the Lunar module's design phase was weight, and there were several redesigns that modified the ship's external appearance from being similar to the CSM to the iconic exoskeleton shape that is instantly recognisable today. Operation Scrape did exactly that, shaving off excess weight in every department, from window size to cockpit seats; the astronauts eventually had to stand up.

The Lunar Module was effectively two craft in one – the ascent stage and the descent stage – that would land together and separate for take-off, leaving the descent stage at the landing site. Eagle, or LM-5 was the first controlled landing as well as the first manned landing. Its descent stage is still on the Moon along with those of Snoopy, Intrepid and Antares.

The ascent stage contained the crew's quarters, as well as thrusters, radars, instrumentation, communication and navigation equipment, ascent propulsion mechanism, batteries and life-support system. Also on board was sufficient oxygen to enable the astronauts to survive the journey back to the CSM.

Meanwhile the descent stage was – after its primary purpose of supplying the landing control systems and landing gear – effectively a cargo hold. Over the course of the Apollo programme the craft carried equipment ranging from portable life-support systems, surface experiment technology, TV cameras, small vehicles, as well as creature-comforts such as additional water and oxygen for the astronauts.

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Details

  • Purpose: Lunar landing and takeoff
  • First use: 20 July 1969
  • Further landings by Apollo 12 and 14 (followed by Extended Lunar Modules Apollo 15, 16 and 17)
  • Crew: 2
  • Internal atmosphere: 100% oxygen at 4.8psi
  • Total mass: 4,700kg
  • Primary guidance, navigation and control system (PGNCS) developed by MIT Instrumentation Laboratory
  • Original design had only three legs, but discarded in favour of four in case one was damaged on descent
  • Apollo 10 dress-rehearsal (excluding landing) took place May 1969
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