Voyager program

The Voyager program is a continuing American scientific program that employs two robotic probes, Voyager 1 and Voyager 2, to study the outer Solar System. They were launched in 1977 to take advantage of a favorable alignment of Jupiter, Saturn, Uranus, and Neptune, and are now exploring the outer boundary of the heliosphere. Although their original mission was to study only the planetary systems of Jupiter and Saturn, Voyager 2 continued on to Uranus and Neptune, and both Voyagers are now tasked with exploring interstellar space. Their mission has been extended three times, and both probes continue to collect and relay useful scientific data.

On August 25, 2012, data from Voyager 1 indicated that it had become the first human-made object to enter interstellar space, traveling "further than anyone, or anything, in history".As of 2013, Voyager 1 was moving with a velocity of 17 kilometers per second (11 mi/s) relative to the Sun. Voyager 2 is expected to enter interstellar space within 2016, and its plasma spectrometer should provide the first direct measurements of the density and temperature of the interstellar plasma.

Voyager program (Mars)

The Voyager Mars Program was a planned series of unmanned NASA probes to the planet Mars. The missions were planned, as part of the Apollo Applications Program, between 1966 and 1968 and were scheduled for launch in 1974–75. The probes were conceived as precursors for a manned Mars landing in the 1980s.

Originally, NASA had proposed a direct lander using a variant of the Apollo Command Module launched atop of a Saturn IB rocket with a Centaur upper stage. With the discovery by Mariner 4 in 1965 that Mars had only a tenuous atmosphere, the mission was changed to have both an orbiter and lander. This required the use of a Saturn V to launch two probes at once. The orbiter would have been a modified Mariner probe identical to that employed for Mariner 8 and Mariner 9, while the landers would have been Surveyor moon probes modified with the use of aeroshells and a combination parachute/retrorocket landing systems.

Funding for the program, like that of the entire AAP, was cut in 1968 and the mission itself was cancelled entirely in 1971, mainly on the grounds that launching both probes on a single rocket was both risky and expensive.