How many times have you been told to ‘stop dreaming and be practical’? For scientists and engineers, both dreams and practical know-how were potent tools to turn the understanding of the physics of gravity and motion into the technology of space travel. Most of the important pioneers of rocketry were inspired to pursue dreams of space travel by reading Jules Verne’s (1828–1905) story From the Earth to the Moon, or the stories of HG Wells
(1866–1946). But they also had a solid grounding in physics and engineering.
propellant, impulse, exhaust velocity, reaction device, thrust, payload, g-force, effectively weightless, lift-off, Kepler’s laws, satellite, ellipse, orbital velocity, eccentric, semimajor axis, periapsis, apoapsis, perihelion, aphelion, perigee, apogee, hyperbola, closed or stable orbit, geosynchronous, geostationary, medium Earth orbit, semi-synchronous, gravity assist, slingshot effect, re-entry, orbital decay, drag, lift, supersonic, hypersonic, shock wave, heat shield, ablation
Figure 2.1.1 The Apollo 11 mission: the launch of a Saturn 5 booster—the largest rocket in history—on its way to deliver the first humans to the Moon
Here we’ll concentrate on the important rocket researchers of the 20th century, the period in which the most rapid scientific advances took place. Below is a list their most important contributions.
Konstantin Tsiolkovsky (1857–1935)
Tsiolkovsky (also Tsiolkovskii), a Russian mathematics teacher, derived the basic rocketry equations including the ‘Tsiolkovsky rocket equation’ (see Physics Phile
‘This is rocket science’, p 30), used Newton’s definition of escape velocity to calculate it for Earth, and proposed multi-stage rockets and steerable thrusters.
He advocated the use of liquid propellants (including liquid hydrogen) because they could be controlled using valves and would give a larger impulse than solids (see in2 Physics @ Preliminary section 4.5). He also wrote science fiction,
predicting space stations, and space colonies using biological recycling of food and oxygen and airlocks for moving between a spacecraft and vacuum.
Robert Goddard (1882–1945)
Goddard, a US physicist, invented and tested many practical aspects of rockets, launching the first liquid-propellant rockets (liquid oxygen–gasoline) in 1926.
He confirmed experimentally that rockets work in vacuum and showed that an hourglass-shaped de Laval steam nozzle greatly increased rocket efficiency. He launched the first scientific payload (camera, thermometer and barometer) that parachuted back to Earth, and steered rockets using vanes to direct exhaust gas and a gimballed (pivoted) nozzle under the automatic control of a gyroscope.
He even experimented with very futuristic ion thrusters. Goddard attracted public ridicule by predicting travel to the Moon (see in2 Physics @ Preliminary Physics Phile p 43). He was mostly ignored by the US government, but he strongly influenced Oberth, von Braun and Korolyov (see below).
Robert Esnault-Pelterie or REP (1881–1957)
REP, a French aircraft designer, wrote on interplanetary travel, calculated the energies and flight times for trips to the Moon, Venus and Mars and proposed atomic energy to power interplanetary craft. With André Hirsch, he established the REP–Hirsch Prize for aeronautics, the first winner being Oberth (below). In 1931, Esnault-Pelterie conducted early experiments with liquid propellants (petrol–liquid oxygen, benzene–nitrogen peroxide and tetranitromethane) and developed a gimballed nozzle.
Herman Oberth (1894–1989)
The German physicist Oberth’s PhD thesis describing space travel was initially rejected as ‘utopian’ (though it was later accepted), so he published it as an influential book By Rocket into Planetary Space. In it he developed equations for space flight, proposed a design for a two-stage rocket using hydrogen–oxygen propellant and described craft for human space exploration. A follow-up book won him the REP–Hirsch Prize, which he used to purchase rocket engines for research assisted by his student Wernher von Braun. He worked (with von Braun) on both the Nazi V-2 rocket program and later the American rocket program. In 1953 he published Man in Space, proposing space stations, space-based
telescopes and space suits.
Figure 2.1.2 Konstantin Tsiolkovsky
Figure 2.1.3 Robert Goddard
Figure 2.1.4 Robert Esnault-Pelterie
Figure 2.1.5 Herman Oberth
activity 2.1 pRacTIcaL EXpERIENcEs
Activity Manual, Page 14
As a student, von Braun (German physicist and aeronautical engineer) tested Oberth’s rocket engines. He was an early amateur researcher in the Spaceflight Society, which was taken over by the Nazis. Under the Nazis von Braun led the team that developed the alcohol–oxygen-fuelled A4 (or V-2) rocket used on Allied cities including London, killing and wounding thousands. After the war, he joined the US army’s nuclear missile program. He dreamed of a civilian space program. In magazines and television, he publicly promoted exploration to the Moon and Mars with permanent colonies and orbiting space stations serviced by re-usable shuttle-type craft.
In 1957 the USSR launched Sputnik, the first artificial satellite, shocking the US and leading to the ‘space race’ of the 60s between the USSR and the US. In response, a civilian space agency, the National Aeronautics and Space Administration (NASA), was formed, and in 1960 von Braun became director of its Marshall Space Flight Center. He became a major figure in the race to the Moon (the Apollo missions) announced in 1961 by President Kennedy.
He led the project to construct the largest rocket ever built—the Saturn 5 (Figure 2.1.1).
As is well known, the US won the race to the Moon in 1969, although they spent much of the 60s catching up to many USSR space ‘firsts’. The race also led to rapid development of civilian satellites for communications, Earth surface–atmospheric monitoring and scientific space exploration.
Sergey Korolyov (also Sergei Korolev) (1907–1966)
Korolyov, a Ukrainian-born Russian aircraft designer, was known only as the
‘Chief Designer’ of the USSR space program—his name was kept secret until his death. He helped set up the Jet Propulsion Research Group, which launched liquid-fuelled rockets in 1933, and led to the USSR government forming the Jet Propulsion Research Institute, with Korolyov as Deputy Chief.
During Stalin’s Great Purge of 1938, Korolyov was imprisoned for 6 years, then released to become a rocket designer in the nuclear missile program, where he quickly improved on the design of captured Nazi V-2 missiles.
Like his US rival von Braun, he dreamed of space travel and tried to convince his government to allow civilian projects. In 1957, he was allowed to launch the first artificial satellite Sputnik into orbit, starting the space race.
He oversaw a string of space firsts (and failures): first animal (dog) in orbit, first unmanned Moon landing, first image of the unseen side of the Moon, first man and first woman in orbit, first extra-vehicular activity (space walk), first fly-pasts of Venus and Mars and more. Launch failures of four N1 boosters (rival to von Braun’s Saturn 5) and Korolyov’s death in 1966 helped to lose the race to the Moon for the USSR.
Gerard O’Neill (1927–1992)
O’Neill, a US physicist, invented the particle storage ring used in particle accelerators, and an early wireless computer network. He led development of a satellite positioning system—a precursor to the US global positioning system (GPS). Through conferences, papers and books, he was an energetic advocate of space travel. He proposed colonies in cylindrical spacecraft positioned at Figure 2.1.7 Sergey Korolyov
Figure 2.1.6 Wernher von Braun
Figure 2.1.8 Gerard O’Neill