However, considered as predictions of humanity's future, these scenarios are dubious, for scientists have long recognized that such personal encounters with comfortingly familiar extraterrestrials are extraordinarily unlikely. Given the inhospitable conditions on other planets and moons in the solar system, they are almost certainly not the homes of advanced beings; given the sheer immensity of the universe, it is improbable that spacefaring aliens from elsewhere would happen to be in our vicinity at this moment in time; and while no one can speak definitively about the characteristics of extraterrestrial life, it seems absurd to expect creatures that evolved on an alien world to bear either a physiological or psychological resemblance to human beings.

Still, it remains possible, perhaps even probable, that humans in space will someday discover tantalizing evidence that proves the existence of alien life: a radio message from a distant star, a telling astronomical observation, or a fossil or artifact left by aliens who visited the solar system thousands or millions of years ago. Such evidence might over time provide humanity with data about a genuinely alien race or civilization. If science fiction, as many commentators have asserted, has a role to play in preparing people for the future, there should be many stories involving this sort of indirect alien encounter. Yet such stories are rare.

In science fiction literature, examples include James Gunn's The Listeners (1972), a classic novel about receiving a radio message from an alien civilization, and James P. Hogan's Inherit the Stars (1977), wherein scientists piece together the story of humanity's ancient interactions with aliens from evidence including a human skeleton buried on the moon and a crashed alien spaceship on Ganymede (although Hogan cannot resist bringing actual aliens into the picture in his sequels to the novel).

In science fiction film, such discoveries have been presented most thoroughly and intelligently in the unheralded CBS television series Men into Space (1959-1960). On the 50th anniversary of the series' debut, I wish to examine eight Men into Space episodes that provide telling advice about what we should really expect to find in our explorations of outer space—and how we should deal with potential evidence of extraterrestrial life.

Men into Space is a key work in the tradition of what I term the "spacesuit" film, and what others describe as the "documentary-style" science fiction film. While there were two distinguished precursors—German director Fritz Lang's Frau im Mond (Woman in the Moon) (1929) and Russian director Vasili Zhuravlev's Kosmicheskiy Reys: Fantasticheskaya Novella (The Space Voyage) (1936)—the subgenre was essentially defined in the 1950s by three American films—Destination Moon (1950), Riders to the Stars (1954), and Conquest of Space (1955)—and two failed television pilots: Project Moonbase (1953) and Destination Space (1959). Despite occasional bits of idiosyncratic nonsense, these films strived to be utterly realistic in depicting how humans would venture into outer space, and all of them scrupulously avoided any meetings with, or even mention of, alien life. Instead, their dramas solely involved the menacing environment of space, dangers caused by malfunctioning equipment, and interpersonal conflicts exacerbated by the harsh conditions and confined quarters of space travel.

In episodes during the first half of its only season, Men into Space followed this pattern in depicting the near-future exploits of stalwart American astronaut Colonel Edward McCauley (William Lundigan) and his colleagues. The only reference to aliens in early episodes comes when an astronaut jokingly explains how he got his wife's permission to travel into space: "All I had to do was promise I wouldn't flirt with any female Martians we might run into." The clear implication is that, in serious stories about space travel, meetings with aliens are something to joke about, not something to expect.

However, the makers of Men into Space faced a unique challenge. Unlike their predecessors, who only needed to generate enough drama to fill one or two hours, Men into Space needed thirty-eight half-hour adventures, for a total of nineteen hours of film, to complete their first season; and there are only so many stories one can tell about spaceships struck by meteors, crucial rockets failing to fire, or feuding scientists causing problems on a space station. The series needed another sort of narrative, and the discovery of alien life in space was one obvious alternative. Yet the producers and writers felt compelled to remain true to their mandate to be realistic in depicting human activity in space.

Thus, later episodes of the series focused on evidence of extraterrestrial life that astronauts might actually find in space, and their message was that such evidence must be approached with the proper balance of openness and skepticism and carefully examined before anyone jumped to unsustainable conclusions. As the series demonstrates, there are three possible explanations—the evidence is fraudulent, is a natural phenomenon being misinterpreted, or is authentic—as well as the possibility that astronauts will be unable to determine whether the evidence is genuine or not.

A case of fraud occurs in the nineteenth episode of the series, "Dateline: Moon" (aired February 10, 1960). Chosen by lottery to be one of the first two journalists to visit the moon, sleazy reporter Jimmy Manx (Harry Lauter) is not content to chronicle what McCauley describes as the "awesome and terrible beauty of the moon" or the activities of human explorers on its surface. Instead, seeking a spectacular scoop, Manx has someone construct a rectangular object with strange markings, then takes the rectangle to the moon and plants it where he knows an astronaut will retrieve it. Properly skeptical, McCauley insists that no announcement of the discovery be made until experts on Earth examine the object. Manx then violates orders during a live television broadcast from the moon and displays the object. Knowing that his hoax will fall apart if the object makes it back to Earth for scrutiny, Manx then steals the object and tries to hide it on the lunar surface. A suspicious McCauley follows him and catches him in the act, proving that it was all a hoax—which scientists on Earth later confirm.

In the episode's concluding scene, McCauley confides that despite his doubts, "Somehow I wanted to believe it," adding that "[m]an has always wanted to know if there are intelligent beings, or at least life, in the universe." Indeed, McCauley's strong desire to uncover evidence of alien life will become a recurring theme of later episodes: in "From Another World," alien life is described as McCauley's "favorite dream," and in "Mystery Satellite," McCauley says that "[s]omeday a human being is going to make contact in space, and when it happens it's going to be the greatest thing in the history of mankind. I have to admit that I'd kinda like to be that man." As Men into Space shows, this natural desire to find evidence of aliens will problematize efforts to prove their existence. Not only does it create opportunities for self-serving deception, as in "Dateline: Moon," but it can also lead overactive imaginations to detect signs of alien life when none exist, a tendency that even the level-headed McCauley eventually falls victim to.

Still, in the first of three episodes following this scenario, "Shadows on the Moon" (the twenty-fifth episode, aired March 30, 1960), McCauley is never fooled by apparent indications of the presence of intelligent aliens on the moon. When crewmates point out that a large outcropping of rock appears to resemble a smiling human face, McCauley correctly argues that it was not carved by aliens, but is only a natural formation that coincidentally resembles a face. An astronaut then observes what appear to be signal lights on the face—but they turn out to be nothing more than reflected sunlight. Finally, one crewman panics and runs away when he thinks he sees some sort of ambulatory being larger than a man. McCauley later discovers that the crewman saw only his own distorted reflection in a large slab of obsidian glass. In rejecting their outlandish claims, McCauley tells his colleagues that "[t]he only enemy is the moon itself," insisting that there could be no alien beings in its forbidding environment.

Yet McCauley himself is briefly convinced by bogus evidence of alien life in two later episodes. In the twenty-seventh episode, "Lunar Secret" (aired April 13, 1960), McCauley's crewmate on a lunar mission takes a photograph that, when examined later, apparently reveals an object of artificial origin. Follow-up photographs further indicate that the object has somehow shifted its position, deepening the mystery. However, when they finally climb the difficult slope to examine the object at close range, they find that the moving object is actually two objects in different positions—objects that happen to be alternately undetectable in the photographs. Specifically, they're the helmets of dead American astronauts, members of a failed mission to the moon whose fate had been previously unknown.

And in the thirty-seventh episode, "Mystery Satellite" (aired September 7, 1960), McCauley's spaceship is approached by a mysterious vehicle that assumes a parallel course—suggesting an intelligent navigator of some sort. After another spaceship burns up in the atmosphere while pursuing this vessel, McCauley goes after the mystery vehicle, and when it again positions itself near his spaceship, he flies directly toward the moon and changes course at the last minute, hoping to trick the object into crashing into the moon, which it does. McCauley then lands and determines that the pursuing vehicle is only an old robot satellite of human origin.

Having dealt with one hoax and three cases of mistaken identity, Men into Space nonetheless argues that skepticism about evidence of alien life is not always appropriate, balancing these four episodes with two episodes illustrating the third possibility—that the imagined evidence of alien life or intelligence is genuine—along with two episodes that leave the authenticity of the evidence as an open question.

In "Is There Another Civilization?" (the twenty-fourth episode, aired March 23, 1960), a small meteor made of an artificial alloy strikes a rocket returning to Earth. McCauley leads a follow-up mission to the meteor swarm, retrieves a large object that was obviously part of some space vehicle, and returns it to Earth. Scientists then determine that the fragment came from a spaceship that was 500 years old, establishing its alien manufacture. And in the twenty-ninth episode, "From Another World" (aired April 27, 1960), McCauley reports that while visiting an asteroid near Earth, he observed the fossilized imprint of a prehistoric bird just before he fainted and had to be returned to the ship. Knowing of his desire to detect alien life, superiors assume that the overworked McCauley imagined the imprint as a form of wish fulfillment and ground him for six months. Later, McCauley and another scientist are allowed to return to the asteroid on a mission that, due to the asteroid's eccentric orbit, can only last one hour, but are unable to find the fossil. Yet the camera shows viewers that, just beyond where he stopped, the fossil is clearly visible. Still, McCauley is vindicated when a rock retrieved by the scientist turns out to conceal an image of a claw—not a fossil, but more provocatively, the work of a primitive artist and thus evidence of not only life, but intelligent life as well.

One might argue that both episodes ignore other possible explanations. Perhaps there existed, centuries ago, a secret society of advanced human scientists who built and launched a spaceship; perhaps the asteroid was a fragment from Earth, hurled into space by some fantastically powerful volcanic explosion. However, these theories seem even more unlikely than posited alien intelligence, so it is logical to maintain that, barring additional revelations, the existence of alien life is the best explanation of the phenomenon.

Finally, in the first of two episodes where matters are left unresolved, "Beyond the Stars" (the 31st episode, aired May 11, 1960), we interestingly observe what many believe will be the actual way we establish the existence of extraterrestrial intelligence: radio astronomy. While McCauley and other crewmen use a radio telescope to scan space from the far side of the moon, they record one man's improvised song about being on the moon:

Darling to you I sing from the moon
Into the void of sky.
Hear from the stars, forever my love
Words that will never die.

The series' thirty-eighth and final episode, "Flight to the Red Planet" (by some reports aired September 14, 1960, by other reports never aired), similarly concludes with an unresolved mystery. After McCauley and his crew fly to the Martian moon Phobos and set up observational equipment to determine the feasibility of landing on Mars, the mission's scientist reports that he has observed green areas surrounding the Martian canals, strongly suggesting that there is indeed life on Mars, and that intelligent beings designed its canals as irrigation channels. Naturally enough, the episode ends with the scientist looking forward to an actual landing on Mars "next time," but McCauley responds, with a sardonic expression on his face, "Next time? Maybe."

There are two ways to interpret this episode. First, contemporary television audiences have grown accustomed to series that end their seasons with a "cliff-hanger" episode designed to leave viewers in suspense until the next season's first episode completes the interrupted story. Thus, many might assume that "Flight to the Red Planet" was designed to make people eagerly anticipate a second season of Men into Space in which McCauley and his colleagues would actually land on Mars and encounter life: exotic plants, strange creatures, perhaps even intelligent beings. However, I am skeptical of this theory for two reasons. First, it was not the habit of television series of the 1950s and 1960s to end their seasons with unresolved dramas. Second, the television business in the early 1960s had a leisurely pace, and low-rated series were usually allowed to complete their seasons even when networks had no intention of bringing them back. Thus it seems almost certain that, when they were filming their final episode, the producers of Men into Space already knew that their series had been cancelled and that there would be no second season, and that would allow us to regard McCauley's "Next time? Maybe," as a bitter in-joke. In other words, if they had wanted McCauley to land on Mars and meet some Martians, they would have done so in this episode, because it represented their final opportunity.

Instead, I submit that the producers of Men into Space knew exactly what they were doing in crafting this final episode, and they provided their series with the only appropriate ending for a realistic film about space travel and evidence of alien life.

As previously intimated, I believe that science fiction should occasionally strive to be genuinely predictive to help humanity prepare for the future. But in the case of predictions of discovering alien life, there are clear limitations on what science fiction can do. If intelligent aliens actually exist, they will almost certainly be truly alien beings, and humans will be fundamentally unable to anticipate their nature and behavior. If human writers attempt to portray aliens in detail, then inevitably, as Stanislaw Lem has argued, they will be able to do little more than create distorted mirror images of humans like themselves. As noted, such depictions of "not-particularly-alien" aliens may be memorable in their own ways, but they will be useless as stimulating predictions of actual alien encounters.

Instead, in order to convey even a marginally authentic picture of what humans can expect when they come into contact with aliens, writers must restrict themselves to offering tantalizing hints of strange and poorly understood aliens, which will suggest a genuinely alien presence without any futile effort to provide specifics. This is precisely what Lem himself did in his most famous novel, Solaris (1961), twice adapted as a film (1972, 2003). It is also what we observe in the greatest spacesuit film, 2001: A Space Odyssey (1968), wherein the alien manipulators of humanity remain unseen and mysterious. While not a work of similar quality, the series Men into Space intelligently took the same approach, offering only scraps of data about strange aliens who built spaceships, drew images of ancient birds, and perhaps constructed canals on Mars. Ending the series with humans on Phobos, speculating about evidence of possible advanced life on Mars, was therefore the only proper way to conclude its narrative.

In the decades since Men into Space, as the desire to detect signs of extraterrestrial intelligence moved out of the science fiction genre and into mainstream culture, all of the scenarios that the series predicted have been realized. We have seen fraudulent "evidence" of alien life, including the notorious video of the Roswell "alien autopsy" and numerous faked photographs of alien spacecraft. There have been cases of misinterpreted data, the most spectacular example being a real-life replay of the storyline from "Shadows on the Moon": that stunning photograph of a "face on Mars" apparently carved on the surface by intelligent humanoids (which, when reexamined in higher-resolution photographs, turned out to be an ordinary and rather un-facelike Martian mesa). There has been one discovery of seemingly authentic evidence of alien life, a Martian meteorite found in 1984 that was announced in 1996 to contain signs of microorganisms, though doubts have emerged as to whether the evidence is in fact definitive. Finally, there has been at least one case where a possible message from intelligent aliens has been neither confirmed nor denied: a strange radio burst from outer space, received at Ohio State University on August 15, 1977, which remains unexplained to this day. And real-life observers have generally responded to these findings in the manner of McCauley: keenly interested in these indications of alien life but reluctant to believe until careful study eliminates any chances of fraud or misinterpretation.

So, we can laud Men into Space for correctly anticipating how humans would—and should—react to the discovery of evidence of extraterrestrial life; but the series wisely did not attempt to describe what might occur after such a discovery: the process of actually learning about and interacting with aliens genuinely unlike anything in human experience. For that is something that science fiction can never really prepare us for.