Voyager (1967)

Prior to the exploration missions to the outer regions of the solar system, a precursor to manned Mars missions in the 1970s and 1980s was proposed under the name Voyager. This proposal emerged in January 1967, when NASA initiated efforts to garner congressional support for Voyager. This occurred at a challenging time for NASA, as the Apollo 1 fire had recently occurred, leaving legislators disinclined to engage in discussions about NASA's future. In a recent entry on Beyond Apollo, space historian David S. F. Portree details the untold story of the envisioned Voyager that never came to fruition.

In 1960, the Jet Propulsion Laboratory (JPL), located in Pasadena, California, initiated the Voyager program with the goal of developing robotic space probes to explore Mars and Venus in the 1960s and 1970s. Managed by the California Institute of Technology under contract with NASA, the program was formally approved in 1964. However, various obstacles, such as budget cuts and new data about Mars from the Mariner IV flyby in 1965, delayed NASA's formal push to start Voyager until January 1967.

In January 1967, NASA's Office of Science and Space Applications released a 26-page booklet as part of its efforts to transition from planning to the development of Voyager. Homer Newell, NASA's Associate Administrator for Science and Space Applications, highlighted that the chosen launch vehicle for Voyager was the "impressive" Saturn V. A single three-stage Saturn V rocket would launch two 12-ton Voyager space probes toward Mars.

The booklet presented Voyager as part of an evolutionary Mars exploration program, leveraging the low-energy transfer opportunities between Earth and Mars occurring every 26 months. Mars was favored over Venus as the first target for Voyager due to more favorable exploration conditions.

Voyager's planning retrospectively included Mariner IV in its program, which had returned detailed images of Mars in 1965. However, new atmospheric data forced a redesign of Voyager's landing system, increasing the projected cost to over $1 billion. The booklet also proposed new Mariner flybys of Mars in 1969 and 1971, aiming to photograph the entire visible disk of the planet and release a small sterilized probe into Mars' atmosphere to measure various variables.

The first Voyager missions, scheduled for 1973, would include a lander and an orbiter. These vehicles relied on Radioisotope Thermoelectric Generators (RTGs) for electricity, allowing the landers to survive for a Martian year. The 1977 and 1979 missions would introduce a Mars surface rover and biological experiments to study any life found in previous missions.

Despite efforts, Congress refused to fund Voyager in the 1968 fiscal year, leading NASA to formally abandon the plans in September 1967. However, in 1968, Congress agreed to fund the Viking program in the 1969 fiscal year. Viking, a project similar to Voyager, succeeded with the landing of Viking 1 in 1976.

The name Voyager was recycled in 1977 for missions to Jupiter and Saturn, which then continued toward Uranus and Neptune, becoming the Voyager missions beyond the planets. Both probes remain operational and have surpassed 22 years in their "Interstellar Mission." Currently, Voyager 1 and Voyager 2 are at significant distances from Earth, continuing their journey beyond the Solar System.