Gyroscopes are devices familiar to any child that has played with a spinning top. They nonetheless manifest one of the most fundamental of our physical laws, form a key element of many technologies and require complex mathematics to fully describe.

A gyroscope basically comprises a store of angular momentum, in the form of a heavy disk spinning around a slender pivot or shaft. The conservation of angular momentum is as fundamental to physics as conservation of linear momentum and conservation of energy. Since angular momentum has an associated direction (in this case along the axis of rotation), the gyroscope will attempt to remain pointed in the same orientation even when moved. This provides a way of determining direction and angle of elevation, even in a moving vehicle. Moreover, if mechanically connected to another mass, the gyroscope will apply a torque, trying to bring the whole body into the same alignment.

These properties have been exploited for centuries for toys, and, in the nineteenth century, began to be incorporated with other machinery, providing stabilisation to devices such as compasses, and even being used on ocean vessels.

Even before gyroscopes came into their own as tools in the era of aviation and rocketry, they presented a fascinating theme to science fiction writers.

A more unusual application is described in An Experiment in Gyro-Hats, a short story published by Ellis Parker Butler in 1910. As with much early science fiction it describes an eccentric inventor - in this case a hat-maker who is determined to find a use for the vacant space found in top hats. When his daughter falls in love with a man with balance issues, he decides to install a gyroscope in a top hat, together with a vacuum pump to secure it to the crown of the head. This presents him with something of a challenge of nomenclature:

“The gyroscope is, as everyone knows, a top, and I might have called the hat I invented a top hat, except that any tall cylindrical silk or beaver hat is called a top hat, so I was forced to adopt the name of gyro-hat.” 

The purpose of this device is to keep the subject upright when required [1]:

“If a gyroscope was placed in the top of a top hat firmly fastened to the head of a man, and the gyroscope set going, that man would remain perpendicular in spite of anything. He could not stagger. He could not reel. He could walk a line as straight as a crack.”

The device does indeed resolve the problems of the inventor’s prospective son in law, although it doesn’t function in quite the way the hatter plans.

Another example of an adventurous inventor introducing the world to applications of gyroscopes can be found in Jenkin’s Gyroscope by L H Robbins, a short story which appeared in Munsley’s Magazine in March 1921. This narrative is written in the first person, from the point of view of a writer character who has himself written a science fiction story.

As he explains, as a young accountant he encountered the novels of H G Wells and, aiming to better himself before proposing marriage, decided to write a novel in which gyroscopes are used as a form of suspension to ensure a smooth ride in vehicles. After successful publication, and several ups and downs in his life and affairs, an actual engineer takes up the idea and begins actually installing gyroscopes in vehicles. While it’s not clear Robbins understood what a gyroscope actually does, and the story never explains its precise application, it’s certainly interesting to see the self-reflectivity so common in science fiction here: in the narrative, the industrial revolution’s inventions inspired Wells, who inspired another science fiction author, who inspired further inventions!

The increasing diversity of applications, including to the developing submarine technology, is further demonstrated by stories like A Maelstrom of Atlantis by Joseph W M Skidmore (Amazing Stories, 1936). Here an innovative diving bell is equipped for self-stabilisation:

“As you see, there is a six inch space between the outer and inner shells. This space is filled with eighteen hundred and forty-two steel balls that can rotate freely in a heavy oil. Thus the balls act as bearings and also take up the space between the two shells. Therefore the compression resistance of the depth globe is equal to the strength of the two shells. Inside the inner shell, where we three must be, there are two powerful gyroscopes set at right angles to each other. The gyroscopes make it possible to hold the inner shell in any desired position, even though the outer shell is rotating. Thus if the depth globe is caught in whirling currents, the inside globe can be kept stationary so that it will cause no discomfort to us.”

However by 1930, gyroscopes were being used for developing an automatic pilot for aircraft - a development reported in magazines of science and adventure fiction such as Air Wonder Stories and Science Wonder Stories (both edited by Hugo Gernsbach). The extrapolation of this to rocket ships in science fiction was rapid and natural. Some of the early greats of the pulp-era adopted gyroscopes with abandon, and they feature as rocket guidance and stabilisation devices frequently in the works of E E Doc Smith (e.g. Skylark of Valeron, Spacehounds of IPC, Galactic Patrol, published as short stories 1931-1938), John W Campbell (e.g. the stories in The Black Star Passes, The Mightiest Machine, Islands of Space, all originally published as short stories 1930-1935) and others.

The German V-Weapons of World War II - long distance, rocket-propelled missiles - used gyroscopes (with a varying degree of success) to stabilise their trajectories. This brought the technology to increasing public attention, and gyroscopes, or just gyros, were soon ubiquitous in science fictional rocket stories.

The short story Stability by A Bertram Chandler (Astounding, 1946) both demonstrates the use of gyroscopes for spaceship handling and hinges itself to some extent on gyroscopic principles. The cargo ship Canis Majoris uses large flywheels to turn its nose before firing its main rocket engines, but also has smaller gyroscopes that act as a stabiliser - triggering attitude thrusters to correct its direction when the ship turns off course:

“The stabilizer hung in its gymbals as it always did, humming gently to itself, a mere toy compared with the big flywheel used to swing the ship’s head in any desired direction when falling free. Power of its own it had very little, yet through its circuits and relays it ruled the steering jets, could and did keep the vessel vertical relative to the surface”

This operation is, of course, particularly important when the rocket is attempting a landing. Unfortunately, a cargo of supposedly-inert protoplasm despatched from the Jovian moon Ganymede climbs up the cargo hold, shifting the rocket’s centre of gravity and making her unstable beyond the capacity of the stabiliser to correct. The crew are faced with the dual challenge of landing an unstable ship and doing so somewhere the corrosive, mindless but motile Ganymedian creature cannot cause harm.

Murray Leinster’s novel Space Platform (1953) is another example from this era of rocket-oriented science fiction where gyroscopes become central to the plot. In this story (the first in a short series), the world’s first spacecraft is designed to be a large space station which will be lifted, intact, to orbit from the United States.

A young man, Joe Kenmore, is dispatched from his family firm to deliver a set of ultra-sensitive gyroscopes to provide stability to the station. When these are badly damaged due to an act of sabotage, Kenmore and his newly acquired friends - including a native American technician, Mohawk Chief Bender, and another technician, Mike Scandia, with dwarfism - save the day by rebuilding the sensitive devices. The sense of triumph when the repaired gyroscopes are activated is palpable:

“Mike left the gyros spinning so that the main axis pointed at the sun, invisible through the shed’s roof. And then all four of them watched. And visibly and inexorably, the pilot gyros followed the unseen sun, and they would have resisted with a force of very many tones any attempt to move them aside by so much as one-tenth of a second of arc - which would mean something under one three-millionth of a right angle. And these pilot gyros would control the main gyros with just this precision, and after the platform was out in space could hold the platform itself with the steadiness needed for astronomy of an entirely new order of precision.” (pg 115, 1965 Belmont edition)

As this suggests, scientific research, as well as military advantage, is a motivating factor for this station. Joe and his friends are crucial to its success and developing other innovative techniques which revolutionise the journey into space and onwards to the Moon [2].

Grendel, by Larry Niven (appearing in the collection Neutron Star, 1968) is a novella in the Known Space series and features Niven’s reluctant hero Beowulf Schaeffer. In the climactic sequence of the story, a starship called (ironically) the Drunkard's Walk lands with one of its three landing legs damaged. It is held upright by the gyroscope flywheels aboard, but as they exert a torque to stop the ship falling, they lose energy and have to try to spin faster until they fail catastrophically and transfer that momentum to the vessel around them. The consequences for the ship are not pretty:

“I was on the way down when Bellamy looked at me; and in the next instant the Drunkard’s Walk spun end-for-end, shrieking. The nose gouged a narrow furrow in the soil; but the landing legs came down hard, dug deep, and held. Bellamy sailed high over my head and I lost him in the sky. The ship poised, braced against her landing legs, taking spin from her dying flywheels. Then she jumped.
The landing legs acted like springs, hurling her somersaulting into the air. She landed, and jumped again, screaming, tumbling, like a wounded jackrabbit trying to flee the hunter. I wanted to cry. I’d done it; I was guilty; no ship should be killed like this.
Somewhere in her belly the gyroscope flywheels were coming to rest in a tangle of torn metal.”

By this point, gyroscopes were effectively accepted technology. Gyro-cars and gyro-copters became a common part of science fiction worldbuilding - with the names often used without any explicit mention of gyroscopic stabilisation. Examples include a vast range of science fiction in every media, including toys such as the Dan Dare gyro-car.

Gyroscopes also continued to appear more accurately in serious science fiction, as for example, in radio play Journey Into Space: The Red Planet (BBC radio, 1954, by Charles Chilton) where they are used as a tool for rotating each ship in an exploration fleet several degrees before engaging their rocket thrust, in order to avoid an obstruction in the asteroid belt. However gyroscopes themselves became less likely to form the focus, or even a significant component of a story.

A couple of interesting exceptions do occur. In the fiction of rotating space stations such as O’Neill cylinders, for example, gyroscopic physics comes into play. If a station’s spin axis is held perpendicular to the ground surface when it is spun up, then as it orbits Earth it will keep the same alignment and so be seen from the surface at a variety of angles. Even if it is spun up so its solar panels face the Sun, after a few days or weeks in orbit the spin axis would no longer be solar-oriented. The bigger the mass of the object, the worse the problem of controlling or correcting for this effect with thruster rockets or other mechanisms. As a result, Gerard O’Neill proposed that large cylindrical space stations should be built in pairs, each rotating in the opposite sense and so cancelling the other’s gyroscopic torque. This is seen, for example, in the design of space station Babylon Four (which had two counter-rotating carousels), but not the smaller Babylon Five, in the television series named after the latter.

A slightly less reverent nod to gyroscopic principles is also seen in "The Doomsday Men" - a serial from the 1970s children’s television series The Tomorrow People. Here a set of bagpipes (of all things!) thrown into the complex gearing of the United Nations space station Damoclese forces its rotating section to seize, thus applying a torque to the rest of the station, and leading it to tumble out of its planned orbit.

Gyroscopes, or more generically gyros, continue to form part of world-building in science fiction - mentioned in passing in modern science fictions such as The Expanse, For All Mankind, Star Trek and Star Wars. Perhaps more importantly, gyros continue to be fundamental to human space technology in the real world. They form a crucial part of the control and orientation systems of any space craft. The Israeli Beresheet moon lander is believed to have crashed due to a gyro failure; the International Space Station is equipped with four gyroscopes for attitude control; and - as Leinster predicted in the early 1950s - gyros are crucial for the precise orientation required by space telescopes.

Indeed the end-of-life point for the venerable Hubble Space Telescope is likely to occur due to gyro-failure rather than any other technical problem. Launched with six high precision gyroscopes, Hubble was designed to operate with three active gyros at any one time. Four of the high-wear, high energy devices were replaced in 1993 and all six during the last servicing mission in 2009. However, due to repeated failures since this last repair visit, Hubble now has only two remaining, and has recently been forced into single-gyro operation mode, in which it cannot create such sharp and stable images as astronomers have become accustomed to, despite using magnetometers, sun sensors and star trackers to replace some of the gyroscope orientation information. If another failure occurs, the telescope would be forced to deorbit, since any further failure risks the spacecraft beginning to tumble, and - as it is too large to burn up in an uncontrolled re-entry - it could land with devastating impact in an inhabited area if control is lost. However while the gyros are arguably Hubble’s Achilles' Heel, the fact that these devices have lasted as long as they have, in a hostile environment and operating with extraordinary precision, represents a technical triumph that has enabled extraordinary science.

The form of gyroscopes - their spinning disks and the rings against which those are aligned - will always continue to fascinate, and are used as a science-fictional short-hand even where gyroscopic behaviour itself is irrelevant. The physics of gyroscopes and their simple, but - to the uninitiated - apparently rather spooky ability to “know” where they are pointing, also fascinates. Gyroscopes are now ubiquitous in modern technology, from telescopes to cruise ships and smartphones. They have been reduced to microscopic sizes on computer chips, and appeared as vast alien-inspired constructs in science fiction such as the 1997 film Contact. If they have lost some of their attraction to science fiction writers, it is not because their physics is any less intriguing, or indeed any less dependable. With an anticipated return to human trans-lunar spaceflight, it is more than possible that the capabilities of gyroscopes, and their essential role in spacecraft navigation will once again rise in the public awareness. Gyroscopes may once more make the leap from children’s toys to symbolising the peak of human achievement.