It was the 25th of August, in the year 1609 when an Italian astronomer and philosopher, Galileo Galilei, presented his new eight power telescope to merchants in the city of Venice, Italy. The telescope had been invented in the Netherlands one year earlier. Galileo had taken the newly developed theories of others and built his own telescopes. In that year, while a professor at Padua University, it is believed that he was the first to observe the planet Mars through a telescope in his quest to explore the heavens.
He recorded his earliest telescope aided observations in 1610 in his pamphlet Sidereus Nuncius (latin meaning “A Starry Messenger”). Although he mentions observing Mars in passing he provides no details of those observations and focuses mostly on his observations of the Moon and Jupiter and includes information about the development and construction of his telescopes.
Galileo is known to have made observations of Mars that allowed him to see, for the first time, rare retrograde motion of the planet. It had not been possible to detect this without the development of the telescope. He is also credited with being the first to observe phase changes on the surface of the planet.
Speculation About Water Ice
Early Telescopic observations of Mars continued through the 17th century with the notable discovery that Mars had a polar cap. This was observed by Gian Cassini in 1666 and a few years later Christiaan Huygens recorded observing Mars with a south polar cap. That the polar cap was white in appearance lent itself to speculation that it may have been evidence of water. The first suggestion that this may be the case came with Giacomo Maraldi who in 1719 observed the polar caps and noted that the pole was bordered by a dark band that he interpreted to be melt water.
However, it is British astronomer William Herschel who is credited with being the first to specifically claim that the poles could be composed of water ice after first observing them in 1781. From his measurements he estimated the inclination of the axis of the planet to the plane of the orbit to be 28°. On Earth this gives rise to the seasons – spring, summer, autumn and winter. Herschel suggested that the observed changes seen in the polar cap regions of the planet were the seasonal melting of snow and ice by the sun.
An Explanation of Obliquity
On Earth, this axis tilt is called the obliquity and is it 23.5°; meaning that the Earth’s axis of rotation is tilted by 23.5° (or 23.4°) from a line perpendicular (at 90°) to the orbital plane, known as the ecliptic. The angle between the Earth’s axis of rotation and the ecliptic is 66.6° – or two thirds of a right angle. There is a preference to express the angle however as a tilt from the imaginary, ideal axis of spin that would be at a right angle to the plane of the ecliptic – in Earth’s case 23.4°.
Interestingly, the Earth’s tilt varies between about 22.1° and 24.5° over a cycle of about 40,000 years. At higher inclination (a larger tilt) seasons are exaggerated giving hotter summers and colder winters. It is perhaps worth considering this a little more and its expected effect on the object on our study, the planet Mars, whose tilt (its oblique) is 28°.
An Early Rationale for a Martian Atmosphere
In 1784, William Herschel in an address to the Royal Society stated of Mars:
“It appears that this planet is not without considerable atmosphere; for besides the permanent spots on the surface, I have often noticed occasional changes in partial bright belts; and also a darkish one… These alterations we can hardly ascribe to any other cause than the variable disposition of clouds and vapours floating in the atmosphere of the planet… Mars has a considerable but modest atmosphere, so that its inhabitants probably enjoy a situation in many respects similar to our own.”William HerscheL, an address to the Royal Society, 1784
By the 19th century astronomers continued observing Mars and as the years passed, and their telescope construction and the optics used in them continued to advance, they were able to see with more clarity the planet than had been investigated by Galileo and Cassini two hundred years earlier. The technological advances had progressed enough now to allow astronomers to study in more detail the surface of the red planet.
In the 1830’s Johann Heinrich von Madler and Wilhelm Beer studied the dark regions of the planet Mars and they noticed changes to the dark areas surrounding the north polar cap that had first been observed by Giacomo Maraldi over a hundred years earlier. They too concluded that it could be the result of water originating from the pole and suggested that the dark areas might be wet, marshy soil – moistened by melting polar ice. In 1858, Angelo Secchi (who was an astronomer and a catholic priest) suggested that the dark areas of Mars were seas separated by lighter continents.
Fingerprints In Light
By the late 19th century a scientific technique that allows the chemical composition of materials to be determined by virtue of the light that it interacted with had been developed. In the technique, called spectroscopy, light that was either reflected from a materials surface or light that was transmitted through a material. The light detected would be altered by the medium it passed through as selective absorption of certain frequencies of light would take place. This gave a fingerprint-like signature of the medium whose characteristic components could, if the signal was strong enough, indicate the molecular composition of the material. When coupled to a telescope, this allowed for the first time the chemical signature of distant materials to be studied. In 1867 two astronomers Pierre Janssen and William Huggins took the technique and applied it to their astronomical observations of the planet Mars.
In their telescopic observations light from the sun was reflected from the surface of another planet (in this case Mars) and that sunlight was also transmitted through the martian atmosphere. The chemical composition of the martian surface and the composition of the martian atmosphere would both be expected to cause light reflected from the sun to be changed. In the process of transmission through the atmosphere certain frequencies of light (which is electromagnetic radiation) would be preferentially absorbed by molecules present. In measuring such light back in the 19th century of course would involve telescopes mounted on the Earth’s surface, staring at Mars through the Earth’s atmosphere. To eliminate the problem of seeing material present in the Earth’s atmosphere the scientists used light from the Earth’s moon as a control giving them a clean baseline for their measurements.
Looking at light in the visible region (optical spectra) they compared it to that of the Moon and found that the Moon (the control) did not show absorption lines indicating the presence of water. However, light from the atmosphere of Mars did show the absorption lines indicating the presence of water vapour on the red planet. This work was repeated by other astronomers and confirmed by both Vogel in 1872 and Maunder in 1875.
It’s worth remembering that this was 1867. We will be looking at the saga of NASA’s unusual behaviour regarding water on the planet Mars later. Suffice to say for the moment that, for some reason, the discovery of water on Mars and it’s announcement by spokespersons for NASA and its contractors such as Malin Space Science Systems became a bit of a joke. The search for water (a prerequisite for life) on the red planet’s surface and announcement of its discovery seemed to be functioning in some sort of gatekeeping capacity. Were people in the administration simply optimising their revenue streams with positive stories of disclosure and discovery? Or was something else going on?
Giovanni Virginio Schiaparelli was a prolific Italian astronomer and the director of the Brera Observatory in Milan. Earlier in his career he had focused his studying comets and meteors and while in Milan he had discovered that swarms of meteors follow paths through space in common with comets. This work secured him a powerful 8.6 inch reflector telescope that he wanted to test out to see if the instrument possessed the qualities required for studying the surface of planets.
As luck would have it Mars was about to come into a favourable opposition that would become known as the “Great Opposition” of 1877. An “opposition” in this case is the term used when two planets (such as the Earth and Mars) are at their closest point to each other in their orbits around the sun. On some oppositions conditions such as the slight variation in the orbits (such as Mars being closer to the sun and the Earth being a little further from the sun than its average), good viewing conditions on the Earth from the observer and an absence of dust storms that would otherwise reduce visibility in the Martian atmosphere come together to make a really great opposition as it was in 1877 with Mars a mere 35 million miles away.
It was during this period that he drew the first detailed maps of the surface of Mars. Maps that he would eventually add detail to later during later oppositions. Schiaparelli in creating his map gave names to various features that stood out, drawing from latin and mediterranean place names found in ancient history and mythology. Many of which are still used to this day.
One of the most noteworthy features of Schiaparelli’s original map was the curious network of linear markings that criss-crossed the Martian surface, joining the various dark patches to each other. He referred to the lines in his native tongue (Italian) as “Canali” meaning lines or channels. Controversy soon followed when “Canali” was mistranslated into the English word “Canal”. Now Canali, which means channel, is not suggestive of anything other than linear features. Canal however invoked images of artificial networks built by the inhabitants of the planet Mars. However, Schiaparelli maintained his own naturalistic view of canali.
During the 1879 Mars opposition he refined his earlier drawing and noted some changes. An apparent invasion of a bright area that he called Libya by an area he called Syrtis Major led him to his belief that Syrtis Major was a shallow sea which at times flooded the lands around. He drew in more canali and, for the first time, reported what he called doubling or gemination of one of these features. Of the reality of the canali, if not their exact nature, he was utterly convinced “It is [as] impossible to doubt their existence as that of the Rhine on the surface of the Earth”.
More Spectroscopy of the Martian Atmosphere
At the turn of the 20th century, on two occasions in 1895 and 1905, astronomers attempting to reproduce the spectral lines for water failed to detect them. Twenty years had passed since the discovery and confirmation of water vapour in the Martian atmosphere has been made. Now, however, instruments that should be at least as sensitive, if not more sensitive, found no evidence for water vapour in the Martian atmosphere.
Some concluded that the initial findings had been refuted and that the early discoveries were simply in error. However, another conclusion can be drawn. Simply that all the observations had been correct. In the 1870’s Mars had water vapour in its atmosphere and by around the 1900 that water vapour had gone. Was Mars undergoing a change?
Percival Lowell was a mathematician, an author and a businessman before he became determined to study Mars and take up astronomy as a full-time career. In the winter of 1893 to 1894 he built the Lowell Observatory in Flagstaff, Arizona. At an altitude of over 2,100 metres and with few cloudy nights and far from city lights the location, given the name Mars Hill, was ideally situated for astronomical observations. It was from this observatory that Lowell made his observations of the red planet, his observations and research published in his numerous books.
His books included detailed descriptions of what he termed “non-natural features” on the planet’s surface. In his writings of the “canals” on Mars, unlike Schiaparelli, whose canali were agnostic in regards to intelligent design, Lowell considered the canals as artificial constructions. He documented what he called “oases” at the intersections of the “canals”, noting that both “canals” and “oases” underwent changes to their visibility periodically. He went on to theorise that Mars was home to an advanced but desperate culture. It’s inhabitants had built the canals to transport the water found in the polar regions; the last source of water on an inexorably dying planet.
By the turn of the 20th Century many astronomers had been unable to observe the linear features that Lowell and Schiaparelli had called canals and canali. This led some astronomers to consider that canali were an optical illusion; one caused by a psychological tendency to connect indistinct features into a more comprehensive whole.
However, in 1905 there was a resurgence in interest when astronomer C. O. Lampland took photographs from the Lowell Observatory on Mars Hill that showed thirty eight “canals”; for which he received an award from the British Royal Photographic Society in 1909.
Once again, evidence of the martian environment, in this case terrain features, had failed to be observed only to reappear at a later date. Had the missing canali simply been due to other observatories being used with poorer optical qualities than was available at Mars Hill? Was the existence of the canali a problem of subjectivity of the observer perhaps? Or, just perhaps, was this another clue towards the idea that Mars was undergoing radical cyclical environment change?
Surface changes and the Martian Environment
In 1912 Svante Arrhenius, a Swedish chemist proposed a chemical explanation for the changing surface reflectivity on Mars. Surface reflectivity (called albedo), Arrhenius believed, underwent change on the surface on Mars due to some simple chemical reaction brought about by the melting polar ice.
In the 1920’s Nicholson and Pettit used the light coming from Mars to estimate its surface temperature. They found that at midday, the equatorial regions reached a temperature of 15°C (or 60°F). However, at dawn temperatures were as low as -85°C (or -120°F). Their experiment was not sensitive enough to measure the temperature at the polar regions due to the low intensity of the light.
For context, the lowest temperature recorded for the Earth’s surface was recorded by a satellite of eastern Antarctica in August 2010 where it reached -94.7°C (-135.8°F). Ted Scambos of the National Snow and Ice Data Center who made the announcement told The Guardian “It’s more like you would see on Mars on a nice summers day at the poles.”1
By 1950, Clyde Tombaugh of the Lowell Observatory had proposed that the canals on Mars were radial fractures caused by meteorite impacts on the surface. And that their periodic appearance and disappearance was caused by the ebb and flow of plant growth on the martian surface.
Mars is at its closest point to earth every two years, however the variability in the orbits of Earth and Mars mean that the actual distance during the opposition varies dramatically. During the “Great Opposition” used by Schiaparelli in 1877 Mars was 35 million miles (56 million kilometers) from the Earth. At other oppositions this can vary over time to over 100 million kilometers.
Mars has a much larger eccentricity than the Earth; eccentricity is the amount that a body’s orbit deviates from a perfect circle. As a result the distance between Earth and Mars during opposition varies significantly. However, this eccentricity also means that Mars is at times much closer to and then further from the Sun than is nominal during its orbit than would be the case for the Earth.
As we travel around the Sun on our planet Earth, our planet will receive more heat and light from the Sun as its orbit strays a little closer to the Sun; and as it moves a little further away we receive less light and heat from the Sun; factors that do affect the Earth’s climate. This effect of periodic variance to the light and heating of Mars by the Sun is more pronounced on Mars due to its greater orbit eccentricity. The Earth’s complex weather systems also play a part in regulating and mitigating changes to the input of energy from the Sun on global temperature, in effect dampening the variation.
Summary of Telescopic Observations
Four centuries ago the advent of the telescope had opened up the heavens a little more and given those early explorers glimpses of other worlds. Astronomers were beginning to explore the red planet from the Earth when conditions were right. It allowed them to see Mars as more than a tiny reddish disk in the night sky.
The early pioneers of Mars exploration, from Galileo who introduced the telescope to the practice of astronomy to both Schiaparelli and Lowell who, while worlds apart in a number of ways, share a passion for discovery and coming to know the red planet.
The observations made during this early period of studying Mars revealed an Earth-like yet desolate planet. It provided tantalizing hints that it could perhaps harbour life, civilisation even. It was clear however, this was not the balmy, stable environment that we enjoy on the Earth by any stretch of the imagination. It was a cold and hardy environment compared to that of the Earth. Surface temperatures had been seen to rise above the freezing point of water in the equatorial regions, yet the same terrain was frigidly cold at dawn with morning temperatures of -80 °C (-112 °F). The temperature during the day varies by as much as 95°C (171 °F). This was not a hospitable planet by any stretch of the imagination.
That Mars had polar caps had led to the ideas that these polar caps were composed of water ice; and these had been seen to change through the seasons, over the 687 day Martian year. Water vapour had been detected in the martian atmosphere on several occasions and on other occasions it was not detected at all. The seasonal surface changes had been ascribed to various causes including the presence of an atmosphere, advancing and receding seas and even advancing and receding vegetation. More generally chemical changes to the surface of the planet were given as the cause; one that would accommodate both ideas of surface water or vegetation giving way to bare barren terrain. Advancing and receding bodies of water and advancing and receding vegetation would both constitute observable chemical changes to the planet’s surface.
Of the Canali, these were seen to be massive linear features criss-crossing the planet. Thought by some to be artificial channels for the transport of water from the polar regions, by others to be fractures caused by meteor impacts on the surface of the planet. But had they simply been an optical illusion? An artifact of a conscious mind and the human eye straining to resolve low resolution images. Was the power of the human brain filling in the blanks from preconceptions? Or was there another example of transient martian phenomena; there one moment and gone the next?
Nikola Tesla and his Magnifying Transmitter
To call Nikola Tesla a pioneer is understating his contribution to our technological world. All modern power distribution and production systems are based on the designs he conceived of over a century ago. He invented the polyphase alternating current generator that used a rotating magnetic field to change mechanical energy into electrical energy more efficiently than any generated that had come before. His mentor, Professor Thomas Edison, had famously laughed at the design saying to Tesla that a perpetual motion machine will never work. Edison was to eat humble pie when Tesla’s resulting AC (Alternating Current) electricity system proved to be massively superior to the DC (Direct Current) electricity system he pioneered. Some of Tesla’s more “out there” inventions never took a foothold and this wasn’t helped by Tesla often keeping certain details of his inventions to himself.
His experiments with resonance led him to invent the Tesla Coil which became the core of his projects. The tesla coils are radio frequency oscillators that are used to generate high voltages at low current and these are still used today. He had found that by running a wire that was connected to his resonator around his laboratory, it imbued the air with electromagnetic energy. The energy was great enough to light a fluorescent bulb held in his hand because the voltage drop through the air was great enough to allow current to flow. It was reportedly the case that he was able to light bulbs up to a distance of one kilometer using an adaption of the coil called the magnifying transmitter that utilised the energy fields of the earth to allow the transmission of electrical power.
Tesla did an extraordinary amount of work in order to understand the electrical nature of the Earth, both in the ground and in the atmosphere. It was while experimenting with this device that Tesla believed he discovered an artificial signal coming from outside of the Earth.
In the early 1930’s Karl Jansky had also been monitoring electrical disturbances in thunderstorms and had noticed three types of static at 20 MHz distinct from that of thunderstorms. For this work he is regarded as the father of radio astronomy.
However, many believe that it was Nikola Tesla who first identified extraterrestrial sources as originating radio signals:
“We are getting messages from the clouds one hundred miles away, possibly many times that distance. Do not leak it to the reporters.”(1899)
“The feeling is constantly growing on me that I have been the first to hear the greetings of one planet to another.”(1901)
“I refer to the strange electrical disturbances, the discovery of which I announced six years ago. At that time I was only certain that they were of planetary origin. Now, after mature thought and study, I have come to the positive conclusion that they must emanate from Mars.”(1907)
“To be sure we have no absolute proof that Mars inhabited… Personally, I base my faith on the feeble planetary electrical disturbances which I discovered in the summer of 1899, and which according to my investigations, could not have originated from the sun, moon or Venus. Further study has satisfied me that they must have emanated from Mars.”(1909)
“Twenty-two years ago, while experimenting in Colorado with a wireless power plant, I obtained extraordinary experimental evidence of the existence of life on Mars. I had perfected a wireless receiver of extraordinary sensitiveness, far beyond anything known, and I caught signals which I interpreted as meaning 1–2–3–4. I believe the Martians used numbers for communication because numbers are universal.”(1922)
It has been argued that Tesla may have mistaken the origin of the signals as being from Mars when it is likely that he was listening to the singlet, doublet and triplet signals that appear in high frequency radiation emanating from the planet Jupiter.
Perhaps this was the case but did it account for the use of numbers that Tesla noted?
It is said that Tesla was heavily influenced by the writings of Percival Lowell when he formulated his conclusions about the origin of the signal.
Science Fiction or Science Fact?
With writings such as H. G. Wells’ 1898 novel The War of the Worlds and the various incarnations of the story told through the media of both radio (Orson Welles, Columbia Broadcasting 1938) and cinema (Byron Haskin dir., Paramount Pictures, 1953) the idea of martians was to many people a real possibility.
Other works such as Edgar Rice Burroughs’ A Princess of Mars series of books (that was made into the movie John Carter released by Disney in 2009) gave a more fantastic and more human-like touch to the Martian races.
So it was, after flying saucers made their mark on the United States in July of 1947, the cinematic exploration of ideas about them gave the world movies such as Earth Versus The Flying Saucers (Fred Sears dir., Columbia Pictures, 1953) and my personal favourite Invaders From Mars (William Cameron Menzies dir, Twentieth Century Fox Film Corp,1953). Upon this canvas the popular belief was that, just perhaps, Martians were waiting for us to find them across the gulf of space.
This was science fiction, yes. However, at the advent of the space program in 1950, we did not have an answer to the question of, not only life on Mars, but the existence of intelligent life on our closest neighbouring planet.
What would we discover when we began to explore Mars in more detail?