In the next few years, an alignment of the planets of the Solar System will be favorable to the sending of space missions to Uranus and Neptune, the two planets furthest away from the Sun. Among the projects is Trident, a low-cost mission proposed by the JPL and the Lunar and Planetary Institute. This very fast flyover mission from Triton, Neptune’s satellite, will take advantage of the technical performance of New Horizons.
In the field of robotic exploration of planets, launching opportunities are rare. Indeed, sending a space mission to explore these planets and their satellites is very expensive, on the order of several billion euros. Ten years of travel are needed to reach them and a huge expenditure of energy is needed to brake and get into orbit around them.
The next favorable deadline, corresponding to an adequate alignment of the planets of the Solar System, will be around 2031-2032. This is the only opportunity before many decades. To take advantage of this alignment, as in their time the two Voyager missions of NASA, the mission to project these distant worlds have been offered space agencies.
While there is little doubt that a mission to Neptune and Uranus will be launched, presumably in an international setting, low-cost missions with more targeted and limited objectives could also be decided.
Interest in Uranus and Neptune has grown considerably since thousands of similar exoplanets have been discovered. It should be known that these two planets are of a different nature from Jupiter and Saturn. Their highest density classifies them in a separate category: that of the “Ice Giants” to which many of the exoplanets that have been discovered belong. Studying them would make it possible to know what constitutes the interior of these celestial bodies. And, by extension, to better understand the formation of our own Solar System.
Among the low-cost projects being considered, researchers from the Jet Propulsion Laboratory (JPL) and the Lunar and Planetary Institute propose the Trident flyover mission from Triton, a Neptune satellite. This mission would build on the legacy of New Horizons and capitalize on the technical performance of the spacecraft and its overflights of the dwarf planet Pluto, its Charon satellite, and the asteroid Ultima Thule. New Horizons, the NASA spacecraft launched in 2006, has effectively demonstrated the scientific value of rapid overflights in the vicinity of these objects.
With a speed of several kilometers per second, Trident’s encounter with Triton will be just as fast. The probe will use a range of instruments similar to those embedded on New Horizons. They will feature large apertures and high-resolution angular sensors capable of observing Triton from far distances to overflight.
Triton would be a potentially livable world
Just like Saturn’s satellite, Enceladus, scientists have discovered geysers on its surface whose presence is probably explained by the existence of a hydrothermal activity involving water and heat. Trident will be able to observe the activity of the Triton plume and study it more closely.
The presence of these geysers suggests that Triton would harbor an underground liquid ocean, such as Enceladus, but also Europa, Ganymede, Titan and even Ceres and other bodies of the Solar System. This ocean would be the result of geothermal heating. Combined with the presence of organic molecules, the presence of liquid water and energy could also mean that Triton is able to sustain life.
The last mission to visit Triton was the spacecraft Voyager 2, which flew over the moon in 1989. If the mission Trident was decided, it could be launched in 2026 to Jupiter whose gravitational assistance will then allow him to join Triton.