Mariner and Viking

While there was substantial progress made in telescope technology during the 70 years after Lowell’s sensational observations, it was still beyond the abilities of astronomers of the time to unequivocally disprove his theories. In fact, during this period there was little sustained interest in planetary astronomy, and as a result, few new discoveries were made. In 1957, the Soviet launch of Sputnik opened vast new opportunities for scientific investigations. Once the concept of robotic planetary exploration was conceived during the coming years, it was taken for granted that missions to Mars would be a priority. Several failed attempts by both the Americans and Soviets to send spacecraft to Mars during the early 1960s, however, delayed the first close up examination of the red planet.[26]

On 28 December 1964, NASA launched Mariner 4 on a mission to explore Mars. About halfway to the planet, the spacecraft experienced technical difficulties that greatly concerned ground controllers. The “Great Galactic Ghoul,”[27] however, was unsuccessful in its efforts at crippling the probe. On 14 July 1965, Mariner 4 made a flyby to within 6,118 miles of the planet’s surface. It was able to relay 22 images back to Earth with its single camera before passing out of range. The data that was obtained from those images, as well as from the spacecraft’s other instru­ments,[28] were nothing less than stunning. Instead of the living planet that Lowell had envisioned, Mariner 4 discovered a surface that was apparently devoid of life and seemingly unchanged for billions of years. In addition, results of an S-band radio occultation experiment found that the Martian atmospheric density was con­siderably lower than expected and that its makeup was approximately 95% carbon dioxide. Finally, it was discovered that the planet had no discernible magnetic field. The information returned by Mariner 4 resulted in a complete revision of human thinking about Mars, ending forever Lowellian theories regarding vegetation and intelligent beings.[29]

During the early months of 1969, the Americans and the Soviets each sent two more spacecraft towards Mars.[30] While the Soviets continued their string of failures, both Mariner 6 and Mariner 7 were successful. These spacecraft, like Mariner 4, were designed as flyby missions, but they were capable of photographing the planet at much greater distances. Mariner 6 sent 75 images earthward, while Mariner 7 produced 126 photographs. In total, the two probes, which passed within 2,120 miles of the planet, returned data about approximately 20% of the surface. Once again, the information obtained showed a largely cratered landscape, although it also showed large expanses that were like an exceedingly dry and cold desert.[31]

As chance would have it, the first three Mariner missions explored some of the most geographically lackluster areas of Mars. Launched on 30 May 1971, Mari­ner 9, the first successful orbiter to reach Mars, finally revealed the topographical diversity of the red planet. When the spacecraft arrived in November, however, the planet was obscured for weeks by a massive dust storm. Two Soviet landers, Mars 2 and Mars 3, were lost in the storm, because they were not capable of waiting in orbit for it to clear. They did, however, become the first machines to reach the Mar­tian surface. A month after Mariner 9 reached orbit, the dust finally cleared, and it was able to begin mapping the planet. The first features that were discovered were a series of gigantic shield volcanoes—the largest being Olympus Mons, the largest known mountain in the solar system. The second major finding was the immense Valles Marineris system, which dwarfed the Grand Canyon and stretched one-quar­ter of the way around the planet. Finally, the spacecraft detected wide channels (reminiscent of river valleys) and the hummocky terrain that is characteristic of the south polar regions. In October 1972, when the probe ran out of fuel, it had taken 7,239 photographs and revealed a truly unique planet.[32]

After the success of the Mariner program, the next step in the exploration of Mars involved sending robotic vehicles to conduct in situ experiments. In the late summer of 1975, Viking 1 and Viking 2 were launched to the red planet to carry out a search for Martian life, among other scientific objectives. Each spacecraft actually had two separate components—an orbiter based on Mariner 9 technolo­gies and a lander equipped with various scientific instruments. On 20 July 1976, about a month after it had entered orbit and seven years after the first human land­ing on the moon, the 1,300-pound Viking 1 lander settled onto the western slopes of Chryse Planitia—it was the first probe to safely reach the planets surface. The lander quickly began photographing its surroundings, including a stunning 300- degree panorama that showed sand dunes, a large impact crater, low ridges, scattered boulders, and a pink sky.[33]

The Viking 1 lander was outfitted with a large array of sophisticated equipment, including: antennas for communicating with ground controllers on Earth; cam­

eras capable of transmitting photographs in black and white, color, and infrared; a mechanical arm capable of scooping soil for examination; and a meteorology boom for assessing atmospheric humidity, temperature, and wind speed. Eight days after landing, the mechanical arm went into action and scooped up its first sample of Martian soil. The soil was released through a funnel that automatically separated it for chemical and biological analysis. While the findings of the landers various experiments were initially ambiguous, it is the widely held opinion of most of the scientific community that they revealed no signs of Martian life.[34] The Viking 2 lander, which touched down on Utopia Planitia on 3 September 1976, similarly

revealed a Mars with no visible signs of living organisms. Despite the conclusions drawn by mission scientists that Mars was lifeless, however, there is still active debate regarding the possibility that the red planet once harbored life. When the durable Viking 1 lander finally ceased operations in November 1982, the first phase of robotic exploration of the planet officially came to an end. Although many of the beliefs that had endured during the first two-thirds of the 20th century had been disproved by robotic probes, there remained considerable interest in future journeys to Mars. The question at that time was whether this second phase of discovery would be centered on robotic or human exploration.

The ensuing chapters will examine the events leading up to the announcement of SEI, including an effort by NASA to garner political support for a crewed mission to Mars during post-Apollo planning. The central focus of this story, however, will be a detailed account of the agenda setting process that placed SEI on the govern­ment agenda and the intense political battles that virtually guaranteed that an actual program would not be adopted. Finally, the manuscript will investigate the lessons learned from this failed policy process in an effort to provide a tool to current and future policy makers attempting to garner continued political and public support for human exploration beyond Earth orbit.