Crewed missions remain a dream up to date. Despite that, various launches have seen five robotic spacecraft that is traveling towards the interstellar space. Their missions involved the exploration of worlds that are not within the solar system. Upon finishing their jobs, their journeys farther away from the Sun continued because of their momentum. That did not surprise the Astronomers because that was expected. Based on their design, they were meant to live among the distant stars, eventually. As a matter of fact, only one of them communicates with the Earth. It communicates once an extraterrestrial intelligence crosses its path.
Two of the robotic probes are Pioneer 10 and 11. They go way back to 1972 and is one of NASA’s first missions. With the help of nuclear power, Pioneer 10 achieved the first flyby of Mars and Jupiter. It communicated with Earth for three decades despite the initial plan of 21 months. Its counterpart, Pioneer 11, achieved that too but only after the Pioneer 10. It was also the first spacecraft to encounter Saturn revealing the components of the planet. It also identified new moons.
The other pair of spacecraft is the Voyager 1 and Voyager 2. Their mission began around 1977 when one of the identical probes was first launched. It involved studying the alignment of the outermost planets, which occurs after every 175 years. The planets involved in the rare alignment are Neptune, Uranus, Saturn, and Jupiter.
Whereas Voyager 2 stuck to the initial plan, that of Voyager 1 was changed. Instead, it made its detour past moon Titan of Saturn after the flyby of Jupiter and Saturn. It is the only solar system’s world with an atmosphere thick enough to accommodate a rain cycle. On the other hand, Voyager 2 explored Jupiter, Saturn, Neptune as well as Uranus. For the record, it is the only probe that has been close to Uranus and Neptune. As of now, the two of them are in the interstellar space. However, they still communicate with NASA for more than half a century after their launch.
The last one is the New Horizon, a mission that may be described as dead on arrival. Scientists put up a fight to achieve the approval of a mission of Pluto. In fact, it took them some decades to see it. Despite the efforts, months into the mission, Pluto’s status changed from a planet to a dwarf planet. That did not nullify its findings, including a liquid water ocean, giant mountains, and ice volcanoes. It is also on a path that will lead it out of the solar system. It lacks a golden record and plaque.