Planetary Grand Tour
The Planetary Grand Tour ( German great planetary tour ) was an ambitious plan by NASA to send unmanned space probes to the planets of the outer solar system . The "Grand Tour" was designed by Gary Flandro at the Jet Propulsion Laboratory in the late 1960s on the mathematical basis of Michael Minovitch . It should take advantage of the favorable alignment of the planets Jupiter , Saturn , Uranus , Neptune and the dwarf planet Pluto , which existed in the late 1970s and which will not recur in the following 176 years. A space probe sent to Jupiter can use the gravity of this planet for a slingshot maneuver, thereby increasing the speed and favorably influencing and expanding the trajectory to the more distant planets of the solar system.
The originally proposed mission design provided for four space probes. The first two were scheduled to take off in 1976 and 1977 and fly past Jupiter, Saturn, and Pluto. The other two were to follow in 1979 and pass Jupiter, Uranus and Neptune. The probes should be equipped with multiple redundant systems to ensure reliability during the entire mission period of 12 years and especially during the flight through the asteroid belt .
Cuts to the NASA budget in 1972 nearly prevented the "Grand Tour" missions and the later proposed "Mini Grand Tour" missions. However, many elements of the Grand Tour have been incorporated into the Voyager program . The two Voyager space probes launched in 1977 were originally only intended for a flyby of Jupiter and Saturn. The Voyager 2 mission then used the rare constellation of the outer planets to fly past Uranus and Neptune and is now referred to as the “Grand Tour”.