Throughout the late 20th and early 21st centuries, NASA has made many successful spacecraft expeditions to the Jovian planets. Jupiter has been visited by Pioneer 10 (1972), Pioneer 11 (1973), Voyager 1 (1977), Galileo (1195-2003), and New Horizons (2007). Saturn as well has also been visited by Pioneer 11, Voyager 1, and Cassini, which has orbited the planet since 2004 and will crash into its atmosphere later this year. While Jupiter and Saturn received several visits from spacecrafts, the 1977 Voyager 2 expedition flew-by Uranus in 1986 and Neptune in 1989. Since then, Voyager 2 has been the only spacecraft to visit Uranus and Neptune. Even though observatories on Earth have made further discoveries on the icy planets, Neptune has exhibited interesting changes and abnormalities, which cannot be easily seen due to its vast distance from Earth. In light of these mysteries, it might be time to send another spacecraft to Neptune.
There are many things scientists have yet to understand about Neptune.
- Like the other gas giants, Neptune has great windy weather. Incredibly, its winds can reach up to 500 meters per second, which is four times as fast as Jupiter’s fastest winds, and blow westward opposite its rotation.
- Most planets’ magnetic fields are aligned with their rotation axes. However, along with Uranus, Neptune’s magnetosphere is misaligned from its rotation axis by about 47° and is sporadic in nature.
- Despite its great distance from the Sun and its -260℉ methane clouds, Neptune seems to be generating more heat internally than it receives from the Sun, which is quite unusual.
- Also, Voyager 2 showed that Neptune had a “Great Blue Spot,” like Jupiter’s Great Red Spot, but the spot has disappeared from view by the time observatories on Earth started to examine the planet, leaving scientists to wonder where it went.
There have been a few proposals to start expeditions, but funding has been a major obstacles. At NASA’s request, the Jet Propulsion Laboratory has proposed sending a spacecraft to Uranus and Neptune in the 2020’s and 2030’s, but these proposals have not been finalized. Previous plans had been announced before, but they never came into fruition. In the 2011 decadal survey, there was a proposal to send an orbiter to Uranus, but it was set aside for the late 2020’s. Any Neptunian spacecraft would be quite expensive itself, as it would have to rely on nuclear energy to reach the distant planet. Presently, the plans to reach both Neptune and Uranus would each cost $2 billion dollars, so scientists have been trying to find a more cost-effective solution. While sending a spacecraft to Neptune could prove to be a fruitful space expedition, it will take several years worth of scientific studies and peer reviews, budget revisions, and federal funding for the project to take off successfully.
Sources: The Cosmic Perspective: The Solar System- Jeffery Bennett, Megan Donahue, Nicholas Schneider, Mark Voit
Featured Image: Neptune, picture taken by Voyager 2 in August 1989