It is forty years since the launch of the Voyager 2 spacecraft.
The mission was responsible for making the Grand Tour, an unrepeatable trip to visit the four outer planets of the solar system.
On August 20, 1977, a day like today four decades ago, NASA was launching the Voyager 2 spacecraft from the Cape Canaveral station in Florida, United States. Thus began a historic and unrepeatable mission that has allowed us, along with its space counterpart, Voyager 1, to travel beyond the confines of the solar system. What few know is that the first spacecraft took the opportunity of the century to overcome a challenge never seen: to travel the four largest planets of our cosmic neighborhood.
NASA had a historic opportunity: the outer planets had lined up for the first time in more than a century
The fault was actually experienced by a young NASA aerospace engineer named Gary Flandro. During the summer of 1964, while working at the Jet Propulsion Laboratory, the researcher realized that the outer planets of the solar system (Jupiter, Saturn, Uranus and Neptune) were to be aligned in a unique and extraordinary way over the next decade. His calculations, which refined studies done three years earlier by scientist Michael Minovich, showed that it was possible to send a probe between 1976 and 1978 to explore the four worlds at once.
Thus was born Grand Tour, the space mission that took advantage of the gravitational assistance to reduce the journey through space from the initial forty years to only a decade. The last time the planets aligned in the same way had been in 1801. If Flandro’s investigations were correct, NASA had a historic opportunity. Under normal conditions, a ship would have taken more than thirty years to reach Neptune, as the astrophysicist Daniel Marín tells us, a period of time that Voyager 2 could reduce to only a decade, having also the opportunity to visit four planets in one sitting .
Why the first probe was Voyager 2
The two Voyager probes each consisted of a large antenna of almost four meters in diameter and a total mass of more than 800 kilograms. The objective of both missions was to meet with Jupiter and Saturn, later to visit two moons of the solar system. The first, Titan, was especially relevant as it was the only satellite with atmosphere, while the second was Io, the nearest Jupiterian satellite. The Voyager 1 mission was to travel to these two outer planets and the two moons, a risky purpose for which NASA had prepared a plan B. Its second option is that if the later antenna failed, it would be Voyager 2 that Act of substitute, reason for which it received the second number in spite of being sent first from Cape Cañaveral.
In case the late mission achieved its objective, the first antenna would carry out the Grand Tour devised by Gary Flandro. The goal was that Voyager 2, taking advantage of the gravitational pull, would pass through Jupiter, Saturn, Neptune and Uranus. After meeting with the gaseous giant on July 9, 1979 and with the planet of the rings on August 25, 1981, scientists realized that it was possible to achieve the expected challenge as long as all the antenna instruments continued to function normally. This was how Voyager 2 reached Uranus on January 24, 1986 and until Neptune on August 25, 1989. In only twelve years, the initiative had managed to travel farther than ever by capturing impressive images and providing key data about the solar system .
Achieving its goal, however, was not a simple task. If the challenge of Voyager 2 was ambitious, the problems experienced during the launch were greater. Faults in the on-board computer, problems in navigation systems by exceeding speed limits and a malfunction of one of the sensors, which mistakenly indicated an insufficient deployment in extension with the scientific instruments, were only some of the Inconveniences suffered during the first hours after launching in Florida. Ten days later, scientists discovered that one of the propellants of the antenna was not well placed, affecting the structure of the probe and its own trajectory. After correcting the detected problems and redesigning the navigation system, NASA verified in early September, days before the shipment of Voyager 1, that the homologous ship was working properly.
A historical journey beyond the solar system
The technical difficulties experienced during the first weeks, including a fault with one of the instruments of the probe, were not an obstacle to reach the desired objective. All this despite the precarious devices and tools that each of the ships carried, taking into account the current context, with computers that did not exceed sixty and something megabytes in storage capacity and with a speed of sending data back to The Earth of kilobytes per second, according to the physicist Arturo Quirantes. Features that today would blush to anyone, but that allowed us to see for the first time how the outer planets of the solar system were with unforgettable images.
The Voyager 2 spacecraft managed to travel to the four largest planets of the solar system in one go
Upon reaching Jupiter, the ship was able to explore the gaseous giant, its magnetosphere and its moons with unprecedented resolution. Voyager 2 also propelled itself by taking advantage of the gravitational pull to get to Saturn, a route in which it simultaneously was able to portray spectacular photographs and videos on the largest planet in the solar system. Upon arrival at Saturn, the probe captured images of the rings surrounding this world, especially the F ring, and its satellites with much more detail than Voyager 1, which had experienced some technical problems. Achieving both initial goals, NASA decided to continue making history and made Voyager 2 the first mission to reach Uranus and the only probe that Neptune has explored up to date.