In the world of 1964, there were few go-to people when it came to exploring the solar system with robots, especially when it came to actually seeing the planet below. At this time, Russia and America had launched numerous satellites into Earth orbit and flown probes to the moon. But to other planets? The Soviets had attempted Mars six times, but all these missions failed, as did their three attempts to reconnoiter Venus. The United States had succeeded with a mission to Venus in 1962 with Mariner 2. But we must remember that the first Earth-orbiting satellite had been launched only in 1957, so the space age was young.
It was therefore a daring feat when NASA detailed JPL to send twin probes to Mars, Mariners 3 and 4, in 1964. One goal was to transmit TV images back to Earth, both for scientific and political reasons. The political motivations are obvious: we were in a space race with the Soviet Union, a battle of political systems and technological might. While this was paramount with the manned space programs, it had begun with Sputnik and Explorer (the first Soviet and American satellites, respectively), so unmanned exploration was also an important measure of success as well. The scientific ones were also relevant: prior to the success of Mariner 4, Mars had been seen through Earth telescopes in some detail since the mid-1800s, but viewing through the syrupy atmosphere of Earth provided little in optical detail. Mariner 4 had the potential to convert the hazy, fuzzy telescopic images of Mars into relatively crisp, clear images of the planet most like Earth. It was time for the next step.
When JPL set out to build a team to design an onboard camera, one of the heavy hitters it sought out was a Caltech professor named Robert Leighton. Born in 1917, Leighton had attained a bachelor's degree, a master's degree, and a doctorate from Caltech and stayed on as a professor. Leighton was a garrulous fellow, plain-spoken and capable, and never hesitant to speak his mind in easily understood terms. Trained as a particle physicist under the likes of Richard Feynman, his interests ranged wide and far, and he was fascinated by this new and exciting venture. The passion he brought to the program was infectious and helped to make Mariner 4 the great success it was. He was named the principal investigator for the TV-imaging experiment.
Dr. Leighton, who died in 1997, was interviewed numerous times about his ventures into space.1
“In ‘61 or ‘62, I was dragooned by Bruce Murray and Gerry Neugebauer into participating in the Mariner 4 photographic experiment, [the] television experiment, and the reason for that was that there had been no reasonable proposals for a photographic component of the mission on television, for pictorial work. I think people had made studies for NASA of camera systems and stuff like that, some written stuff was available. But nobody had proposed, for that mission, putting together a particular kind of a TV camera.”
Leighton and his team would soon change this. Integral to this project was returning images of Mars; at this point, the romanticized world of Percival Lowell, while extremely unlikely, still could not be entirely ruled out, at least not in laymen's minds. But when the haunting black-and-white images from Mariner 4 did come through, everything changed.
“The reality of it just suddenly waked everybody up. Percival Lowell left us with all that business, ‘waves of darkening' and things. And unfortunately…some of the members of the scientific team are basically romanticists. You know, they are just unbridled romantics…‘if you can't prove that there isn't life on Mars–well, then there must be life on Mars, and let's go find it.’ Well, [Mars changed]. It's got dust storms and polar caps and things.
“It's obvious…there'd be craters and everything. And yet, the fact that craters were there, and were a predominant land form, was somehow surprising. And the [imaging] limitations were so severe…that we waited a week or more, after we knew there were craters, before any kind of official announcement was made. At JPL things were protected very much, because it's one of those things where, if somebody had leaked [the term] “craters”…I think what we were trying to avoid was being drawn into a detailed discussion of things before we had had a chance to make any kind of measurements…so we took a week or two, and made measurements, and then had a press conference.”
Though a physicist by training, Dr. Leighton had become a respected astronomer over the years, specializing in planetary photography. His approach to the needs of the Mariner flights was interesting in this regard.
“Say you wanted to devote a certain amount of money, over a period of time, including mainly space experiments…as a scientific component of the space program, you want to bring back the most science within the area of coverage that you can for the amount of money [you have].
“I think time and again, the atmospheric pressure on Mars, the water vapor on Mars, the temperature of Venus—and there's other things—the rings of Uranus and so on, have come first, or at least equally from ground-based work. And [while] the space work [was] a unique contribution…the prior knowledge of those properties, if we'd known them a few years earlier, could have greatly enhanced the scientific return from the missions that were flown. And so I've always felt that one of the first things NASA should have done was to build four more 200-inch telescopes…as it was, one mission—one damned spacecraft mission would cost as much as five 200-inch telescopes, plus the mountains to go with them.”
He felt that more could be done, once in space, by furthering the knowledge that could be gained from Earth via telescopic observation. However, at this point, imaging from Mars was becoming critical to Mariner 4. But to date, the approach seemed to him to have been somewhat ad hoc:
“We were sort of approached by JPL. The people there had done a lot of thinking about [imaging], but they didn't have any scientists. They had the technical know-how, and had the tubes and everything else, and they'd even sent the Rangers [to the moon]…they had good cameras. And [JPL] had a lot of experience with television cameras and so forth, and to the extent that they thought they were just going to the moon again, they were well up the curve. And so by the time they latched onto a few of the scientists, and we got together and made a group that would do it, it just was a leaderless, headless thing, where there was knowledge…but it was not in places where the people…could propose as a team. So it was a sort of a fluke, in a way.”
So, in the end, was it all worth it? On this point, he seemed assured.
“Oh yes, absolutely. And that's one of the best parts of it all. Some of the letters that came in, from the milkmen, the dairy farmers in Oregon—they'd been watching TV at, I don't know, 5 a.m. or whenever the thing went over [the airwaves]…they said, ‘I'm not very close to your world, but I really appreciate it, keep it going.’ I thought that was kind of nice.”
It was indeed. And it was the beginning of a whole new understanding of Mars.