Next time you’re in an aircraft in the seat over the window, consider that the engine that is about to take you aloft could well have been made by Pratt & Whitney, who also made the engines which put Apollo 11 on the Moon.
It was a huge undertaking, of course, and not only did it involve the engineers at Pratt & Whitney but all up 400,000 engineers, scientists, and technicians from more than 20,000 companies and universities worked on the programme.
Apollo 11 was made up of three parts – the main command module, Columbia; the Service Module; and the Lunar Module, Eagle, which actually landed on the moon. After the mission, Columbia was the only part of the rocket that returned to Earth.
The Command Module might be the precursor to today’s Tiny Houses trend. About the size of a large car, it was the astronaut’s main quarters where they worked and lived. It was 3.2m high, 3.9m round and weighed 5900 kg. It had a blunt nose, which engineers had found worked best in previous Mercury and Gemini spacecraft, which were the manned spacecraft that NASA used in the run up to the Moon landing.
The Service Module was where Columbia drew oxygen, water, and electric power for the command module. The Service Module also housed the service propulsion system – the rocket engines that put the spacecraft into lunar orbit and later boosted it back toward Earth. This module was jettisoned just before reentry into the Earth’s atmosphere.
The Lunar Module, Eagle, was the piece that actually landed on the Moon, hence the famous phrase ‘the Eagle has landed’. As far as the public is concerned, this portion of Apollo 11 is the star of the show. Empty it weighed 3920kg, going up to 14700 once the crew and propellant were loaded. It was 7m high and 9.4m wide.
On descent its engine thrust was 44,316 Newtons maximum and 4710 Newtons minimum. On ascent thrust was 15,700 Newtons. It was fuelled by a 50-50 mix of Unsymmetrical Dimethyl Hydrazine (UDMH) and Hydrazine and the oxydizer was Nitrogen Tetroxide.
To protect it from temperature and micrometeoroids – microscopic particles small enough not to burn up in the Earth’s atmosphere but to drift to the surface instead – there were specially designed materials. Black sheets of heat-resistant nickel-steel alloy, 0.0021072 millimetres (0.0000833 inches) thick, absorbed the Sun’s heat when exposed to the Sun and radiated back into Space. There was also up to 25 layers of thin, gold-coloured film that also protected from micrometeoroids.
The spacecraft got its electrical power from hydrogen-oxygen fuel cells, which convert energy released in a chemical reaction directly to electrical power. A fuel cell continues to supply current as long as chemical reactants are available or replenished (even while the cell is operating).
The advantage of fuel cells over conventional batteries is that they produce several times as much energy per equivalent unit of weight.
As you know, when oxygen and hydrogen combine to form water, energy is released because the electrons in the water molecule are in a lower energy state than those in the gas molecules. In a combustion reaction, as in a rocket engine, the energy appears as heat. In a fuel cell some of it – about 50-60 percent – is converted directly to electrical energy. As fuel cells operate, oxygen and hydrogen combine to produce water as well as electrical power. Apollo crews used this water for drinking.
The fuel cell section contained many individual fuel cells as well as the plumbing and sensors required to supply reactants and keep the cell at the proper temperature.
The reactants were stored in separate tanks in liquid form to reduce space. This required keeping the oxygen at -173°C and at a pressure of 63.26 kilograms per square centimetre. Waste heat from the fuel cells was used to bring the reactants to gaseous form before they entered the cell. The Apollo fuel cell operated at a temperature of about 206°C.
Three hydrogen-oxygen fuel cells were carried in the service module. Each contained 31 individual fuel cells connected in series and operating at 27 to 31 volts. Normal power output was 563 to 1420 watts, with a maximum of 2300 watts. Primary construction materials were titanium, stainless steel and nickel.
By-products of the Space programme – Freeze-dried meals; the Dustbuster mini vacuum; Temper (memory) foam; anti-fogging coating; Nike Airs; studless winter tyres; left ventricular assist device – LVAD (cardiac pump); and fireproof Beta Cloth.
