Why Martians

Why Martians?

For all of our history there has been the fear or hope that there might be life beyond the Earth. In the last centuries this premonition has focused on a bright red point of light in the night sky. In 1894, a Bostonian named Percival Lowell founded a major observatory where the most elaborate claims in support of life on Mars were developed.

Why so many eager speculations and ardent fantasies about Martians rather than, say Saturnians or Plutonians? Because Mars seems at first glance very Earthlike. It is the nearest planet whose surface we can see. There are polar ice caps, drifting white clouds, raging dust storms, seasonally changing patterns on its red surface, even a twenty-four-hour day.

It is tempting to think of it as an inhabited world. Mars has become a kind of mythic arena onto which we have projected our earthly hopes and fears. But our psychological predispositions pro or con must not mislead us. All that matters is the evidence, and the evidence is not yet in. The real Mars is a world of wonders. Its future prospects are far more intriguing than our past apprehensions about it. In our time we have sifted the sands of Mars, we have established a presence there, we have fulfilled a century of dreams.

But Lowell’s lifelong love was the planet Mars. Image Magic Castle Midnight Moonlight by Elena

Percival Lowell dabbled in astronomy as a young man, went to Harvard, secured a semi-official diplomatic appointment to Korea, and otherwise engaged in the usual pursuits of the wealthy. Before he died in 1916, he had made major contributions to our knowledge of the nature and evolution of the planets, to the deduction of the expanding universe and, in a decisive way, to the discovery of the planet Pluto, which is named after him (the first two letters of the name Pluto are the initials of Percival Lowell).

Blues for a Red Planet

Blues For a Red Planet

Many years ago, so the story goes, a celebrated newspaper publisher sent a telegram to a noted astronomer: Were collect immediately five hundred words on whether there is life on Mars. The astronomer dutifully replied: Nobody knows, nobody knows, nobody knows… 250 times. But despite this confession of ignorance, asserted with dogged persistence by an expert, no one paid and heed, and from that time to this, we hear authoritative pronouncements by those who think they have deduced life on Mars, and by those who think they have excluded it.

Some people very much want there to be life on Mars; others very much want there to be no life on Mars. There have been excesses in both camps. These strong passions have somewhat frayed the tolerance for ambiguity that is essential to science. There seem to be many people who simply wish to be told an answer, any answer, and thereby avoid the burden of keeping two mutually exclusive possibilities in their heads at the same time. Some scientists have believed that Mars in inhabited on what has later proved to be the flimsiest evidence. Others have concluded the planet is lifeless because a preliminary search for a particular manifestation of life has been unsuccessful or ambiguous. The blues have been played more than once for the red planet.

In the orchards of the gods, he watches the canals (Enuma Elish, Sumer, c. 2500 B.C.) Image: © Megan Jorgensen

A man that is of Copernicus’ Opinion, that this Earth of ours is a Planet, carry’d round and enlightn’d by the Sun, like the rest of them, cannot but sometimes have a fancy… that the rest of the Planets have their Dress and Furniture, nay and their Inhabitants too as well as this Earth of ours… But we were always apt to conclude, that ‘twas inn vain to enquire after what Nature had been pleased to do there, seeing there was no likelihood of ever coming to an end of the Enquiry… but a while ago, thinking somewhat seriously on this matter (not that I count myself quicker sighted than those great men of the past, but that I had the happiness to live after most of them, me thoughts the Enquiry was no so impracticable nor the way so stopt up with difficulties, but that there was very good room left for probable Conectures.

(Christiaan Huygens, New Conjectures Concerning the Planetary Worlds, Their Inhabitants and Productions, c. 1690).

Life on Mars

Life On Mars

Percival Lowell was electrified by the announcement in 1877 by an Italian astronomer Giovanni Schiaparelli, of canali on Mars. Schiaparelli had reported during a close approach of Mars to Earth an intricate network of single and double straight lines crisscrossing the bright areas of the planet. Canali in Italian means channels or grooves, but was promptly translated into English as canals through Europe and America, and Lowell found himself swept up with it.

Later, in 1892, his eyesight failing, Schiaparelli announced he was giving up observing Mars. Lowell resolved to continue the work. He wanted a first-rate observing site, undisturbed by clouds or city lights and marked by good “seeing”, the astronomer’s term for a steady atmosphere through which the shimmering of an astronomical image in the telescope is minimized. Bad seeing is produced by small-scale turbulence in the atmosphere above the telescope and is the reason of the stars twinkle.

Viking Orbits Mars. No sign of the fabled canals on Mars. Image by NASA in public domain

Isaac Newton had written “If the Theory of making Telescope could at length be fully brought into practice, yet there would be certain Bounds beyond which Telescopes could not perform. For the Air through which we look upon the Stars, is in perpetual tremor. The only remedy is the most serene and quiet Air, such as may perhaps be found on the tops of the highest mountains above the grosser Cloud”.

Percival Lowell built his observatory far away from home, on Mars Hill in Flagstaff, Arizona. He sketched the surface features of Mars, particularly the canals, which mesmerized him. Observations of this sort are not easy. You put in long hours at the telescope in the chill of the early morning. Often the seeing is poor and the image of Mars blurs and distorts. Then you must ignore what you have seen. Occasionally the image steadies and the features of the Planet flash out momentarily, marvellously. You must then remember what has been vouchsafed to you and accurately commit it to paper. You must put your preconceptions aside and with an open mind set down the wonders of Mars.

Collision of a Comet With a Planet

Collision of a Comet With a Planet

Modern planetary scientists sometimes argue that a collision of a comet with a planet might make a significant contribution to the planetary atmosphere. For example, all the water in the atmosphere of Mars today could be accounted for by a recent impact of a small comet. Newton noted that the matter in the tails of comets is dissipated in interplanetary space, los to the comet and little by little attracted gravitationally to nearby planets. He believed that the water on the Earth is gradually being lost, “spent upon vegetation and putrefaction, and converted into dry earth…. The fluids, if they are not supplied from without, must be in a continual decrease, and quite fail at last”. Newton seems to have believed that the Earth’s oceans are of cometary origin, and that life is possible only because cometary matter falls upon our planet. In a mystical reverie, he went still further: “I suspect, moreover, that it is chiefly from the comets that spirit comes, which is indeed the smallest but the most subtle and useful part of our air, and so much required to sustain the life of all things with us”.

Comet West. Anti-comet pills are our salvation. Image Flashing Picture by Megan Jorgensen

As early as 1868 the astronomer William Huggins found an identity between some features in the spectrum of a comet and the spectrum of natural or “olefiant” gas. Huggins had found organic matter in the comets; in subsequent years cyanogen, CN, consisting of a carbon and a nitrogen atom, the molecular fragment that makes cyanides, was identified in the tails of comets. When the Earth was about to pass through the tail of Halley’s Comet in 1910, many people panicked. They overlooked the fact that the tail of a comet is extravagantly diffuse: the actual danger from the poison in a comet’s trail is far less than the danger, even in 1910, from industrial pollution in large cities.

But that reassured almost no one. For example, headlines in the San Franciso Chroncile for May 15, 1910, include “Comet Camera as Big as a House”, “Comet Comes and Husband Reforms”, “Comet Parties Now Fad in New York”. The Los Angeles Examiner adopted a light mood: “Say! Has That Comet Cyanogened You Yet?”, “Entire Human Rase Due for Free Gaseouys Bath”, “Expect High Jinks”, “Many Feel Cyanogen Tang”, “Victim Climbe Trees, Tries to Phone Comet”. In 1910 there were parties making merry before the world ended of cyanogen pollution. Entrepreneurs hawked anti-comet pills and gas masks, the latter an eerie premonition of the battlefields of World War I.

Confusion about Comets

Confusion About Comets

Some confusion about comets continues to our own time. In 1957, Carl Sagan was a graduate student at the University of Chicago’s Yerkes Observatory. Alone in the observatory late one night, he heard the telephone ring persistently. When he answered, a voice betraying a well-advanced state of inebriation, said: Lemme talk to a shtrominer”. “Can I halp you?” “Well, see, we are having this garden party out here in Wilmette, and there is something in the sky. 

The funny part is, though, if you look straight at it goes away. But if you don’t look at it, there ii is”. The most sensitive part of the retina is not in the center of the field of view. You can see faint stars and other objects by averting your vision slightly. Sagan knew that, barely visible in the sky at this time, was a newly discovered comet called Arend-Roland. So he told the man that he was probably looking at a comet. There was a long pause, followed by a query: “Wash’a comet? “A comet, Carl Sagan replied, is a snowball one mile across”. There was a long pause after which the caller requested : Lemme talk to a real shtronomer. 

When Halley’s comet reappears in 2062, we wonder what political leaders will fear the apparition, what other silliness will then be upon us. While the planets move in elliptical orbits around the Sun, their orbits are not very elliptical. At first glance they are, by and large, indistinguishable from circles. It is the comets, especially the long period comets, that have dramatically elliptical orbits. The planets are the old-timers in the inner solar system; the comets are the newcomers. Why are the planetary orbits nearly circular and neatly separated one from the other? Because if planets had very elliptical orbits, so that their paths intersected, sooner or later there would be a collision. In the early history of the solar system.

Halley’s comet. Once around the Sun is a long time if you live in the outer reaches of the solar system. Image A Light Blue Pond by © Megan Jorgensen

Those with elliptical crossing orbits tended to collide and destroy themselves. Those with circular orbits tended to grow and survive. The orbits of the present planets are the orbits of the survivors of this collisional natural selection, the stable middle age of a solar system dominated by early catastrophic impacts.

 In the outermost solar system, in the gloom for beyond the planets, there is a vast spherical cloud of a trillion cometary nuclei, orbiting the Sun no faster than a racing car at the Indianapolis 500. (The Earth is r=1 astronomical unit, 150,000,000 kilometers from the Sun. Its roughly circular orbit then has a circumference of 2 пr = 10(9) km. Our planet circulates once along the path every year. One year = 3 x 10(7) seconds. So the Earth’s orbital speed is 10 (9) km/3 x 10(7) sec. = 30 km/sec. Now consider the spherical shell of orbiting comets that many astronomers believe surrounds the solar system at a distance = 100,000 astronomical units, almost halfway to the nearest star. 

From Kepler’s third law it immediately follows that the orbital period about the Sun of any one of them is about (10(5))3/2 = 10 (7.5) = 3×10(7) or 30 million years. Once around the Sun is a long time if you live in the outer reaches of the solar system. The cometary orbit is 2пa= 2п x 10 (5) x 1.5 x 10(8) km = 10(14) km around, and its speed is therefore only 10(14)km/10(15) sec – 0,1 km/sec = 220 miles per hour. Halley's comet